Synchronous palynofloristic extinction and recovery after the end-Permian event in the Prince Charles Mountains, Antarctica: Implications for palynofloristic turnover across Gondwana

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ncChticdecreased by less than 10%. Comparisons of Gondwanan palynological and lithological data indicate that intense global warming(Twitchett et al., 2001), and it marked the demise of as China, the extinction pattern for Permian marine fossilspecies is threefold: 1) a stepwise disappearance of spe-cies during some 3 Ma immediately below the boundaryReview of Palaeobotany and Palynologhad already begun in the Permian, and that high latitude Gondwana areas such as the PCMs, were affected later than areas to thenorth and west. They also suggest that the end-Permian crisis affected the various Gondwana regions in different ways, but that theend result appears to have been a more equable, sub-humid to semi-arid, and less seasonal climate across southern Gondwana. 2006 Elsevier B.V. All rights reserved.Keywords: PermianTriassic transition; Antarctica; palynostratigraphy; palaeobiogeography; extinction; recovery1. IntroductionThe end-Permian extinction event is known to havebeen rapid in a geological context, lasting b500000 years(Bowring et al., 1998) and perhaps as little as 40000 yearsmuch as 95% of all species on Earth (Benton andTwitchett, 2003). The recovery of global biodiversity topre-extinction family levels is estimated to have taken100 Ma (Hallam and Wignall, 1997). At the PermianTriassic (PT) boundary type locality near Meishan inDepartment of Geology, Geobiosphere Science Centre, Lund University, Slvegatan 12, SE-223 62 Lund, Swedenb School of Natural Resource Sciences, Queensland University of Technology, PO Box 2434 Brisbane, Q 4001, AustraliaReceived 21 December 2005; received in revised form 31 August 2006; accepted 6 September 2006Available online 24 October 2006AbstractIn the Prince Charles Mountains (PCMs) the conformable PermianTriassic (PT) succession is characterised by an abrupttransition from coal-bearing to coal-lacking strata, which coincides with the demise of the Permian Glossopteris-dominated flora.About 32% of the typical Permian spores and pollen are registered for the last time in the uppermost coal. Throughout the earliestTriassic an additional 34% of the lingering Permian taxa disappear, while pioneering typical Triassic taxa appear. This interval ofcontemporaneous stepwise extinction and recovery resulted in an actual increase in spore-pollen taxa diversity during the earliestTriassic. The estimated average sedimentation rate indicates that the 24 m sampling gap that separates the last Permian assemblagefrom the first Triassic one represents ca 96000 years, and that the continued stepwise extinction and recovery lasted for ca325000 years. In the aftermath of the end-Permian crisis only 27% of the typical Permian spores and pollen, that were present fromthe lower McKinnon Member in the Prince Charles Mountains survived to the late Induan, but by then the biodiversity had onlyaSofie Lindstrm a,, Stephen McLoughlin bSynchronous palynof loristic extiPermian event in the PrinceImplications for palynof lorisCorresponding author. Tel.: +46 46 2227875.E-mail addresses: (S. Lindstrm), (S. McLoughlin).0034-6667/$ - see front matter 2006 Elsevier B.V. All rights reserved.doi:10.1016/j.revpalbo.2006.09.002tion and recovery after the end-arles Mountains, Antarctica:turnover across Gondwanay 145 (2007) an extinction rate of 33% or less, 2) a suddendramatic 94% loss of species at the boundary, followed byalaeo3) a gradual loss of a few species that persisted into thelowermost Triassic (Jin et al., 2000). However, followingthe formal definition of the base of the Triassic by the firstappearance of the conodont elementHindeodus parvus atthe base of Bed 27c of theMeishan section inChina (Jin etal., 2000), the main phase of the marine faunal extinctionand the negative 13Ccarb excursion occurs in Bed 25, somehundred thousand years before the PermianTriassicboundary. Data from an independently dated section inEast Greenland clearly demonstrate that the terrestrialecosystem collapse and the subsequent extinction of thetypical Late Permian Subangaran gymnosperms precedesthe PT boundary (Looy et al., 2001; Twitchett et al.,2001), but also show that the floristic turnover was notinstantaneous. The disappearance of the extensive peatdeposits that had characterized the northern and southernhumid climatic zones of Pangea was caused by dieback ofwoody swamp-forest vegetation at the end of the Permian(Looy et al., 1999). Land plant recovery and diversifica-tion after the end-Permian extinction event is consideredto have been relatively slow, taking about 4 Ma (Eshet etal., 1995; Looy et al., 1999). In the Southern Hemisphere,complex coal-forming communities did not reappear untilthe Middle Triassic and were not extensively developeduntil the Carnian, i.e. some 23 Ma after the end-Permiancrisis (Retallack et al., 1996; Anderson et al., 1999).In order to resolve the ecodynamic forces that causedthe global collapse of the terrestrial ecosystem at the PTtransition, it is important to analyze and compare paly-nological data from different PT sections with respectto the climatic and depositional conditions and the flo-ristic diversity that characterized each area at that time. InGondwana, the gymnospermous glossopterids that pro-liferated during the Middle and Late Permian were themost notable terrestrial casualties of the end-Permianextinction event.Several problems confront palaeontological analysisof PermianTriassic transitional sequences of Gond-wana. One is that most of the PT sections weredeposited in non-marine environments and, in theabsence of radiometric data, definition of the PTboundary is based solely on plant and/or tetrapod fossils.The second problem is that in Gondwanan PermianTriassic transitional sequences the palynofloral turnoveris typically associated with either a palynologicallybarren interval or a sampling gap straddling the PTboundary, thus obscuring the signal of short-termecological changes that took place at that time. A thirdproblem is that although many Gondwanan PTtransitions have been investigated palynologically,detailed reports on taxon appearances, extinctions and90 S. Lindstrm, S. McLoughlin / Review of Pchanges in abundance are scarce. Additionally, contin-uous PTsections are uncommon, and in some cases it ispossible that sections are punctuated by hiatuses.A conformable sequence of PT sedimentary rockscrops out in the Prince Charles Mountains, EastAntarctica. During the Late Palaeozoic to EarlyMesozoicthe Prince Charles Mountains area was situated in thecentre of southeastern Gondwana, surrounded by the restof the Antarctic landmass, Australia, India, Madagascarand Africa. Its central position affords the Prince CharlesMountains special importance for correlation of PTsuccessions across Gondwana. This paper describes thepalynofloral turnover across the PermianTriassic transi-tion in the Prince Charles Mountains, and compares it toother gondwanan successions, in order to evaluategeographic and temporal patterns in palynomorphturnover within southeastern Gondwana.2. Geological setting and lithostratigraphy2.1. Tectonic settingThe PermianTriassic sedimentary rocks of theAmery Group that crop out in the northern PrinceCharles Mountains are preserved in a narrow fault-bounded depression called the Lambert Graben (Fig. 1).Exposures are constrained to the west by the AmeryFault and by ice cover in other directions. The LambertGraben appears to be a half-graben as gravity studiesindicate that only the western side (i.e. the Amery Fault)of the Lambert rift is faulted (Mishra et al., 1999). Thetraditional view is that the Lambert Graben developed asa part of a major late Palaeozoicearly Mesozoic failedrift system (Stagg, 1985) that was continuous with theSon-Mahanadi Graben of India prior to the breakup ofGondwana (Fedorov et al., 1982; Stagg, 1985). In theelongate but narrow Lambert Graben, basin fill com-menced with accumulation of alluvial fan deposits con-stituting the Radok Conglomerate (Figs. 1 and 2). Thisunit consists of conglomerates and coarse-grained sand-stones, siltstones and minor coal; the sediments beingderived predominantly from the uplifted area to the westof Amery Fault and transported easterly into the basin(Fielding and Webb, 1995). The succeeding BainmedartCoal Measures incorporate repetetive fining-upwardcycles of sandstone, siltstone and coal that were depo-sited predominantly in northerly to northeasterly flow-ing high-energy braided rivers alternating with low-energy forest mires and floodplains (Figs. 1 and 2;Fielding and Webb, 1996; McLoughlin and Drinnan,1997a; McLoughlin et al., 1997). The cessation of coaldeposition marks the boundary between the Bainmedartbotany and Palynology 145 (2007) 89122Coal Measures and the Flagstone Bench FormationalaeobS. Lindstrm, S. McLoughlin / Review of P(McLoughlin and Drinnan, 1997a,b; McLoughlin et al.,1997). According to McLoughlin et al. (1997), thetransition from the coal-bearing Bainmedart CoalMeasures to the coal-lacking Flagstone Bench Forma-tion marks the transition between the Permian andTriassic (Figs. 1 and 2). The lower part of the FlagstoneBench Formation, represented by the Ritchie Member,comprises sandstones and siltstones that were depositedwith persisting cyclicity (albeit lacking coal) bypredominantly northerly directed rivers under the influ-Fig. 1. Map of the western side of Beaver Lake, Prince Charles Mountains,enlargement of the Ritchie Point area shows the position of the PermianTriathe measured sections of McLoughlin and Drinnan (1997a,b).91otany and Palynology 145 (2007) 89122ence of increasing aridity (McLoughlin and Drinnan,1997b; McLoughlin et al., 1997; Holdgate et al., 2005).The succeeding Jetty Member is represented by typicalred-beds deposited in alluvial fans by easterly directed,episodic flows (Figs. 1 and 2). This unit exhibits agrossly fining-upwards succession of conglomerates,thin and discontinuous massive sandstones, and exten-sive iron-stained mudstones indicative of semi-aridconditions (Webb and Fielding, 1993; McLoughlin andDrinnan, 1997b; McLoughlin et al., 1997; HoldgateAntarctica, showing the distribution of units in the Amery Group. Anssic boundary and the location of palynological samples with respect toalaeo92 S. Lindstrm, S. McLoughlin / Review of Pet al., 2005). Palyno- and macrofloral data from theuppermost Flagstone Bench Formation demonstrate areturn to more moist conditions in the Norian (Fosteret al., 1994; Cantrill and Drinnan, 1994; Cantrill et al.,1995; McLoughlin et al., 1997), when sandstones andminor carbonaceous siltstones of the McKelveyMemberwere deposited by northerly directed rivers (McLoughlinand Drinnan, 1997b; McLoughlin et al., 1997).The traditional scenario that the Lambert Graben wasformed during the Permian as a narrow fault-boundedFig. 2. Stratigraphy and depositional environments of the AmeryGroup. D.F. Mbr=Dart Fields Member; D.T. Mbr=Dragons TeethMember.basin contiguous with the Son-Mahanadi Graben ofIndia has lately been disputed. Boger and Wilson (2003)suggested that all major faulting of the Lambert Grabentook place during the Cretaceous, and that the AmeryGroup sediments were not deposited in a narrow fault-bounded depression, but must have been deposited inone of the many sag basins that formed around thepalaeo-highland of east Antarctica (Tewari and Veevers,1993; Veevers et al., 1996). Additionally, Holdgate et al.(2005) indicated that the petrology and geochemistry ofthe Permian coals of the Prince Charles Mountains aremore similar to those of the Godavari Basin than theSon-Mahanadi Basin of India. Harrowfield et al. (2005)rejected the notion that the Lambert Graben is aprimarily Cretaceous feature. Building on the argumentby Holdgate et al. (2005), they suggested that theLambert and Godavari basins developed in the Permianand were juxtaposed across a broad intragondwanan riftthat later (in the Cretaceous) was reactivated to completeseparation of Antarctica and India.2.2. Latest Permian McKinnon MemberThe McKinnon Member is the uppermost unit of theBainmedart Coal Measures, first named and describedby McLoughlin and Drinnan (1997a). It conformablyoverlies the Grainger Member and is succeeded con-formably by the Flagstone Bench Formation (McLough-lin and Drinnan, 1997a). The McKinnon Member is anapproximately 530 m thick sequence of sandstones,siltstones, shales and coals. Deposition took placewithin alluvial settings, where low-sinuosity rivers tran-sported the sediments in north to northeasterly direc-tions (McLoughlin and Drinnan, 1997a). The lithologiesare basically the same as those in underlying membersof the Bainmedart Coal Measures, but at least in thelower and middle parts of the McKinnon Member thecoal seams are thicker and more abundant (McLoughlinand Drinnan, 1997a). This indicates that extendedperiods of high water tables with low sediment inputmust have prevailed during deposition of that part of themember (McLoughlin and Drinnan, 1997a). Within theupper 100 m of the McKinnon Member the coalseamsbecome progressively thinner and less abundant(McLoughlin and Drinnan, 1997a). Together withincreasing ratios of silica and aluminium oxides in thecoals towards the top of the Bainmedart Coal Measures,this suggests increased weathering and climatic dryingtowards the end of the Permian (Holdgate et al., 2005).Fifteen palynologically productive samples from theMcKinnon Member were investigated. The uppermostbotany and Palynology 145 (2007) 89122sample 95/04 comes from the uppermost coal seam ofFig. 3. Composite lithostratigraphic column of the Permian to Early Triassic sequence in the Prince Charles Mountains, with selected importantpalynoevents. Dotted line I refers to minimum upper boundary of the Lunatisporites pellucidus Zone based on the absence of true Aratrisporites inthe samples below. Dotted line II shows the position of a smaller but first extinction phase prior to the disappearance of the coal. Dotted line III showsthe position of a level with minor accelerated extinction rate and floral change. Asterisk refers to independently dated palynozones (Foster andArchbold, 2001). DTM=Dragons Teeth Member. Australian palynozonations mainly after: 1. Mory and Backhouse (1997), Helby et al. (1987);2. Price (1997).93S. Lindstrm, S. McLoughlin / Review of Palaeobotany and Palynology 145 (2007) 89122the Bainmedart Coal Measures (Fig. 3), just below theupper boundary of the McKinnon Member.2.3. Latest Permian to earliest Triassic RitchieMemberSouth of Ritchie Point on the western side of BeaverLake (Fig. 1) the lowermost member of the FlagstoneBench Formation, the Ritchie Member, conformablyoverlies the McKinnon Member. The Ritchie Memberwas named and described by McLoughlin and Drinnan(1997b), and corresponds to the lower Flagstone BenchFormation of Webb and Fielding (1993). The RitchieMember is distinguished from the preceding McKinnonMember mainly by the lack of coals (McLoughlin andDrinnan, 1997b). The unit is estimated to be more than550 m thick. Medium- to very coarse grained, sub-feldsarenites are the dominant lithology. Thin carbona-ceous siltstones are present in the lowermost part, buthigher in the succession these are replaced by vari-egated, highly ferruginous siltstones (McLoughlin andDrinnan, 1997b; McLoughlin et al., 1997). Thesandstone units are thick, laterally extensive, multi-storey, interdigitating, and exhibiting trough and planarcross-bedding. Many beds contain botryoidal ferrugi-nous concretions and ferruginous laminae (McLoughlinand Drinnan, 1997b). The Ritchie Member wasdeposited by northwesterly to northeasterly directedbraided rivers on an alluvial plain (McLoughlin andDrinnan, 1997b). Four palynologically productive sam-ples were obtained from the lower part of the RitchieMember south of Ritchie Point. The lowermost sample,95/01, comes from a thin siltstone 24 m above the lowerboundary of the unit, i.e. the top of the last coal in theMcKinnon Member (Fig. 3). Other samples fromRitchie Member sediments exposed on FlagstoneBench were analysed for palynomorphs by McLoughlinet al. (1997).Plate I. Selected Permian taxa from the McKinnon Member, illustrated at 625, with sample and slide number and England Finder coordinates, andLO number. Scale bar=40 m. (see plate on page 95)a). Leiotriletes directus 95/10:2 S34/2, LO 9894b). Microbaculispora tentula 95/34:1 O30/3, LO 9895c). Indospora clara 95/28:1 G19/4, LO 9896d). Camptotriletes warchianus 95/26B:2 E22/2, LO 9897e). Didecitriletes ericianus 95/34:1 J29/3, LO 9898f). Laevigatosporites colliensis 95/12:1 Q27/2, LO 9899g). Marsupipollenites triradiatus 95/12:1 P31/1, LO 9900h). Guttulapollenites hannonicus 95/11:1 W38/1, LO 9901i). Protohaploxypinus amplus 95/06:2 K26/3, LO 99029903625,72094 S. Lindstrm, S. McLoughlin / Review of Palaeobotany and Palynology 145 (2007) 89122j). Striatopodocarpidites cancellatus 95/06:2 Y33/4, LOk). Gondisporites raniganjensis 95/04:2 S33/4, LO 9904l). Protohaploxypinus rugatus 95/11:1 U34/1, LO 9905m). Striatopodocarpidites fusus 95/06:2 Q24/2, LO 9906n). Praecolpatites sinuosus 95/26B:1 J29/2, LO 9907o). Scheuringipollenites ovatus 95/22:2 X34/4, LO 9908Plate II. Selected Triassic taxa from the Ritchie Member, illustrated at number. Scale bar=40 m. (see plate on page 96)a). Rugulatisporites trisinus 95/05:1 G26/3, LO 9909b). Triplexisporites playfordii 95/02:2 X40/2, LO 9910c). Densoisporites nejburgii 95/02:1 K39/4, LO 9911d). Uvaesporites verrucosus 95/02:1 U29/2, LO 9912e). Densoisporites playfordii 95/02:1 H25/3, LO 9913f). Falcisporites australis 95/05:1 Q32/1, LO 9914g). Guttulapollenites hannonicus 95/02:1 F35/4, LO 9915h). Lundbladispora sp. 95/02:1 K36/4, LO 9916i). Protohaploxypinus microcorpus 95/01:1 K36/1, LO 991j). Lunatispoprites noviaulensis 95/02:1 W28/3, LO 9918k). Klausipollenites schaubergeri 95/02:1 Q42/3, LO 9919l). Protohaploxypinus samoilovichii 95/02:1 V33/3, LO 99m). Lunatisporites pellucidus 95/02:1 P29/4, LO 9921n). Maculatasporites sp. 95/02:1 N34/4, LO 9922o). Playfordiaspora cancellosa 95/02:2 X40/2, LO 9923with sample and slide number and England Finder coordinates, and LOPlate I (caption on page 94 ).95S. Lindstrm, S. McLoughlin / Review of Palaeobotany and Palynology 145 (2007) 89122Plate II (caption on page 94 ).96 S. Lindstrm, S. McLoughlin / Review of Palaeobotany and Palynology 145 (2007) 89122alaeob3. Palynological investigation3.1. Materials and methodsReconnaissance sampling of the PT transition nearRitchie Point was undertaken during a sedimentologicaland stratigraphic investigation of the Amery Groupduring the Austral summer of 19941995 (by Drs. S.McLoughlin and A.N. Drinnan). Previously, the suc-cession near Ritchie Point was considered to be entirelyPermian in age. The samples were processed usingstandard palynological preparation techniques involvingHF, HCl, and HNO3. Two to three strew slides weremounted from each sample. In some cases the sampleswere subsequently treated with Schulze's solution, andan additional set of slides prepared.Quantitative investigation involved 500 counts of thetotal organic content for each sample, dividing it intocoal and black phytoclasts, wood (brown and black),non-woody plant tissue, cuticles, amorphous organicmatter (AOM), and palynomorph taxa. The palyno-morph taxa/palynodebris ratio was noted, then countingof palynomorphs (or in some cases the palynodebris)continued until reaching 500 specimens. The remainingstrew slides were examined and additional specimens,not included in the count, were recorded. Specimensillustrated are identified with LO+number, and will behoused at the Department of Geology, Lund University.3.2. PalynostratigraphyAustralian Permian and Triassic strata have been thefocus of intensive palynological investigations for manyyears. Hence, the well-established Australian palynozo-nation has become the de facto standard to whichmany other Gondwanan assemblages are compared(Fig. 3). However, there were regional differences inpalynofloral composition within Gondwana during theMiddle and Late Permian. For example, the fern sporegenus Dulhuntyispora contains many key-species forthe Middle to Late Permian, but outside Australia andTimor (Basil Balme, pers. comm. 2005) only D.granulata has been recognised in situ and it is onlyrepresented by a few specimens in South Africa(Anderson, 1977; Backhouse, 1991) and the PCMs(Lindstrm, unpublished data). Despite this provincial-ism, palynofloral investigations of the entire AmeryGroup have now provided a more fully resolvedbiostratigraphic framework for correlation of the PCMsedimentary succession (Fig. 3).The PCM Permian succession is dominated by long-S. Lindstrm, S. McLoughlin / Review of Pranging taeniate bisaccate pollen, mainly Protohaplox-ypinus and Striatopodocarpidites, and non-taenitaebisaccates assigned to Scheuringipollenites. Fern sporesare generally scarce and this renders correlation with theAustralian palynozonation difficult since many of thosezones are based on the first appearance datum (FAD) ofspecific fern taxa. Didecitriletes ericianus is one of theAustralian index species (Backhouse, 1991; Price,1997) that also appears to have a synchronous inceptionin Antarctica (Lindstrm, 1995a), Africa (Anderson,1977) and India (Tiwari and Tripathi, 1992). The firstappearance of this fern spore defines the lower bound-ary of the D. ericianus Zone of Western Australia(Backhouse, 1991), and APP4.2 Zone of Price (1997).In the Bainmedart Coal Measures, D. ericianus has itsFAD in the Toploje Member (Fig. 3).Another fern spore, Camptotriletes warchianus(Plate I, d), first appears in the Dragons Teeth Member.This species was originally described by Balme (1970)from the Salt Range, West Pakistan, where it is a rarecomponent of the Amb, Wargal and Chhidru Forma-tions. In Australia, this taxon has its FAD in the D.parvithola Zone of Western Australia (Mory andBackhouse, 1997), and in the Upper Stage 5 of EasternAustralia (Foster, 1982) or APP5 of Price (1997).Other taxa important in the Australian zonationinclude Triplexisporites playfordii and Playfordiasporacancellosa. In eastern Australia the FAD of these taxamarks the lower boundary of the P. cancellosa Zone(Foster, 1982) or APP6 (Price, 1997), which can becorrelated with the independently dated Early Changh-singian uppermost Chhidru Formation (White Sand-stone unit) in Pakistan (Foster et al., 1997). The P.cancellosa Zone is succeeded by the Protohaploxypinusmicrocorpus Zone, but according to Price (1997) thetransition between these zones differs from area to areaand they lack a clearly defined boundary. They are,therefore, considered subunits of the APP6 Zone (Price,1997). Neither the P. cancellosa nor P. microcorpuszones are recognized in the Prince Charles Mountainssequence. In this succession, both T. playfordii and P.cancellosa have their FADs in the lowermost sample ofthe Ritchie Member, which correlates with the Austra-lian Lunatisporites pellucidus Zone (Fig. 3).The palynostratigraphic definition of the PermianTriassic boundary in Gondwana has long been debated.The first appearance of pleuromeiacean monolete cavatespores assigned to Aratrisporites is favoured by someauthors as a key-taxon for the PT boundary (Fosteret al., 1998), and in Australia Aratrisporites first ap-pears in the Protohaploxypinus samoilovichii Zone(Foster et al., 1998). Because the pleuromeiacean parent97otany and Palynology 145 (2007) 89122plants of Aratrisporites may have been strongly faciesdependent (Retallack, 1975, 1977), some authors in-stead consider the first appearance of gymnospermousLunatisporites pellucidus pollen to mark the PTboundary (Price, 1997) and this is also favoured herein.In the Prince Charles Mountains a few small, incon-spicuous, generally non-spinose Aratrisporites-typespores occur in the Ritchie Member samples fromRitchie Point, but as noted by Price (1997) suchspecimens may instead be small aberrant Lundbladis-pora spores. In the Prince Charles Mountains a singlespecimen of L. pellucidus is registered in the uppermostcoal sample 95/04, but it is consistently present in thesucceeding Ritchie Member samples (Fig. 6). The asso-ciation of taxa, particularly L. pellucidus (Plate II, m),Falcisporites spp., Densoisporites nejburghii (Plate II,c), D. playfordii (Plate II, e), Lundbladispora spp. (e.g.Plate II, h), Playfordiaspora cancellosa (Plate II, o), P.samoilovichii (Plate II, l), P. microcorpus (Plate II, i),and Triplexisporites playfordii (Plate II, b), found in theRitchie Member samples at Ritchie Point allowscorrelation with the L. pellucidus Zone or APT1 ofPrice (1997). The eastern Australian L. pellucidus Zonecan be subdivided based on the FAD of the fern sporeRugulatisporites trisinus (Price, 1997). In the PrinceCharles Mountains spores assigned to R. trisinus (seeremarks under Appendix 1) are rare constituents insamples 95/02 to 05 (Fig. 6). True members of Ara-trisporites have only been recovered in samples fromthe Ritchie Member on Flagstone Bench (Lindstrm,unpublished data). Those were originally considered tobe roughly correlative to the upper two samples (95/07and 95/05) from Ritchie Point (McLoughlin et al.,98 S. Lindstrm, S. McLoughlin / Review of Palaeobotany and Palynology 145 (2007) 89122Fig. 4. Relative abundance of palynodebris in the investigated samples from Ritchie Point in the Prince Charles Mountains.alaeob1997), but are now regarded to be somewhat youngerand equivalent to the P. samoilovichii Zone (Lindstrm,unpublished data). The boundary between the L.pellucidus and P. samoilovichii zones is independantlydated as late early Griesbachian (Foster and Archbold,2001).3.3. Sedimentation rateCalculating the average sedimentation rate for thedifferent units of the Amery Group is difficult. Initialsedimentation in the Lambert Graben was probably firstgenerated and controlled by faulting and mass-wastingof the basin flanks, as is indicated by the alluvial fandeposits of the Radok Conglomerate. The later clasticsedimentation of the Bainmedart Coal Measures wasprincipally governed by axial drainage systems, influ-enced by rainfall, linked to orbital climatic forcing, assuggested by Fielding and Webb (1996), and byMichaelsen and Henderson (2000) for the Late Permiancoal measures of the Bowen Basin, eastern Australia.The coal seams within the Bainmedart Coal Measuresare laterally extensive and the alternation of peat-miresystems and broad sandy fluvial tracts indicates strongcyclic variation in the supply of clastic material. TheMcKinnon Member coals are of sub-bituminous ranksuggesting a compaction ratio of around 6:1 from theoriginal peat beds. The strongly differential compactionbetween peat and sandy beds and the variation in coalseam abundance and thickness means that only a broadestimate of sedimentation rates can be provided for thissuccession. The only useful age constraints available arepalynomorph taxa. In the Prince Charles Mountains, thefern spore Didecitriletes ericianus is first recorded in theToploje Member, 1874 m below the top of the upper-most coalseam, i.e. the interpreted PermianTriassicboundary at 251 Ma. Using the known FAD of D.ericianus in the Late Roadian, ca 269 Ma, indicates anaverage depositional rate for the Bainmedart CoalMeasures of 104 m/Ma. In comparison, the averagesedimentation rate of the Upper Permian BlackwaterGroup in the northern Bowen Basin is 130 m/Ma in thedepocentre, and 70 m/Ma in the more marginal parts ofthe basin (Michaelsen et al., 2001; Michaelsen, 2002).An average sedimentation rate of 104 m/Ma for theBainmedart Coal Measures suggests that the entireMcKinnon Member is late Wuchiapingian to Changh-singian in age.Calculating the sedimentation rate for the Triassic partof the Amery Group is much more difficult. The esti-mated minimum thickness of the Triassic FlagstoneS. Lindstrm, S. McLoughlin / Review of PBench Formation is 760 m (McLoughlin and Drinnan,1997b). The N72 m thick McKelvey Member ispalynologically dated as Norian (Foster et al., 1994),leaving a minimum of 688 m for the pre-NorianTriassic, and with the Carnian/Norian boundary at216.5 Ma this equals a sedimentation rate of ca 20 m/Ma. This very slow sedimentation rate implies a 1.2 Maduration for the 24 m sampling gap at the PT tran-sition. However, this is considered an under estimate ofthe sedimentation rate as part of the Flagstone Benchsuccession is concealed by ice, and because the siltyred beds of the Jetty Member probably represent a longinterval of very slow and episodic deposition in semi-arid environments.There are no definite age constraints for the con-tinuous section at Ritchie Point, and the sedimentationin the Ritchie Member is thought to have been subjectedto strongly fluctuating clastic discharge (McLoughlinand Drinnan, 1997b). If the sedimentation rate for theRitchie Member is equal to that of the precedingMcKinnon Member, the 24 m sampling gap between thelast coal sample (95/04) and the first Ritchie Membersample (95/01) would represent ca 230000 years. How-ever, the upper boundary of the Lunatisporites pelluci-dus Zone is independently dated as mid-Induan (ca250.3 Ma) in Australia (upper lower Griesbachian ofFoster and Archbold, 2001). The absence of genuineAratrisporites from the Ritchie Member samples atRitchie Point suggests that the entire 183 m sampledsection can be assigned to the L. pellucidus Zone. In thatcase, the maximum sedimentation rate for that part ofthe section is 261 m/Ma, indicating that the 24 msampling gap represents only ca 92000 years.4. Palynofloral turnover4.1. The Late Permian stable ecosystemPalynoassemblages of the McKinnon Member indi-cate that the Late Permian vegetation was quite stable inthis area, and not fundamentally different from thatrepresented in the preceding members of the BainmedartCoal Measures (Lindstrm, personal observations). Thispalynoflora is dominated by gymnospermous pollen(Fig. 3), primarily the taeniate glossopterid bisaccatepollen Protohaploxypinus and Striatopodocarpidites,and by the non-taeniate bisaccate pollen Scheuringi-pollenites (Fig. 5). Alisporites species, mainly A.splendens and A. tenuicorpus, are also present in somesamples.Monosaccate pollen are rare, the most commonforms being Densipollenites. Non-saccate monosulcateand polyplicate pollen assigned to Marsupipollenites99otany and Palynology 145 (2007) 89122striatus, M. triradiatus (Plate I, g), PraecolpatitesFig. 5. a) Relative abundance of selected palynotaxa representing major plant groups in the investigated samples from Ritchie Point, Prince CharlesMountains. b) Continued from (a). The following palynofloral events are recognised in the section: (A) Level with a slightly elevated extinction rate11% (4 samples from a 10 m thick stratigraphical interval, diversity=75), proliferation of ferns and sphenophytes, common algae. (B) First extinctionphase (3 samples from a 2 m thick stratigraphical interval) where 19% of the registered spore/pollen taxa disappear (Diversity=69). Similarproliferation of ferns and sphenophytes as at level A. After this level the glossopterids appear to decline in diversity. (C) Second extinction phase (lastcoal sample) last appearance of 33% of the spore/pollen taxa registered in the sample. Demise of glossopterid dominated swamp forests(Diversity=67). (D) Third extinction phase with loss of 14% of the registered spore/pollen taxa, and contemporaneous first major occurrence ofpioneering taxa. Proliferation of peltasperms, corystosperms, ferns and lycophytes (diversity=77). (E) Fourth extinction phase (2 samples from an11 m thick stratigraphic interval) where 35% of the spore/pollen taxa are registered for the last time, and contemporaneous second major occurrence ofpioneering taxa (diversity=99). Continued proliferation of peltasperms, corystosperms and lycophytes, and also proliferation of probable bryophytespores. (F) Increase in corystosperms and continued proliferation of lycophytes and probable bryophytes (diversity=71).100 S. Lindstrm, S. McLoughlin / Review of Palaeobotany and Palynology 145 (2007) 89122alaeobS. Lindstrm, S. McLoughlin / Review of Psinuosus (Plate I, n) and Ephedripites, are also generallycommon. Brown wood is the dominant debris, whereascuticle fragments are generally very rare (Fig. 4). Agenerally low spore/pollen ratio indicates that ferns,sphenophytes, bryophytes and herbaceous lycopsidsplayed a subordinate role in the vegetation. Intervalswith increased spore/pollen ratios are associated withthe large coalseams (Fig. 4), where trilete fern sporesFig. 5 (contin101otany and Palynology 145 (2007) 89122Osmundacidites (and morphologically similar taxa),Horriditriletes and Lophotriletes increase in abundance(Fig. 5). Monolete Laevigatosporites spores alsoincrease in abundance (Fig. 5), but these may representsphenophytes (Balme, 1995).Several taxa, including Didecitriletes uncinatus,Granulatisporites absonus, Horriditriletes ramosus,Protohaploxypinus bharadwajii and P. pennatulus,ued ).have their LADs within a 2 m interval a little less than50 m below the top of the uppermost coal. Proto-haploxypinus samoilovichii, Klausipollenites sp. A,Lueckisporites virkkiae, Indospora clara (Plate I, c),Lunatisporites obex and Chordasporites australiensishave their successive first appearances within theMcKinnon Member (Fig. 6). Throughout this unit thetaxonomic turnover rate is low, except for the samplefrom the uppermost coalseam in which 22 taxa, i.e.33%, have their LADs.4.2. The end-Permian crisis and the taxa thatperishedThe most striking palynofloral change at the end ofthe Permian is a general decline in gymnospermouspollen (Fig. 5), and especially the dramatic decrease ofglossopterid taeniate bisaccate pollen. Protohaploxypi-nus decreases from around 25% to b1% relativeabundance over the 24 m interval from the uppermostcoal sample 95/04 to the lowest Ritche Member sample102 S. Lindstrm, S. McLoughlin / Review of Palaeobotany and Palynology 145 (2007) 89122Fig. 6. a) Palynostratigraphic range chart for the PermianTriassic transition ac) Continued from (b): algal and acritach taxa.t Ritchie Point in the Prince Charles Mountains. b) Continued from (a).alaeobS. Lindstrm, S. McLoughlin / Review of P95/01, and Striatopodocarpidites shows a similarpattern changing from ca 6% to b1% (Fig. taxa groups).Glossopterid pollen do persist in the Ritchie Member,but always comprise b1% of the assemblages. The samepattern in abundance is shown by the non-taeniatebisaccate pollen Scheuringipollenites. The parent plantof this commonly abundant and typically Permianbisaccate genus is unknown, but it may also be alliedto the glossopterids.Many typical Permian Gondwanan taxa that areconsistently present in theMcKinnonMember have theirLADs in the uppermost coal sample, e.g. the majority ofFig. 6 (contin103otany and Palynology 145 (2007) 89122species assigned to Protohaploxypinus and Striatopo-docarpidites, together with Striatoabieites multistriatus,Densipollenites spp., Praecolpatites sinuosus, Floriniteseremus, Microbaculispora tentula (Plate I, b) and Di-decitriletes ericianus (Plate I, e). The virtual disappear-ance of glossopterid pollen can be directly linked to thecessation of coal formation. The disappearance of thepeat-forming mire that hosted the glossopterids is aconspicuous feature of many PermianTriassic transi-tions in southeastern Gondwana. The glossopterids firstappeared during the late Palaeozoic glaciation, steadilydiversified in the ameliorating post-glacial temperate}ued ).alaeo104 S. Lindstrm, S. McLoughlin / Review of Pclimate during the Early and Middle Permian, andmarkedly proliferated in the humid Late Permianclimate. The glossopterids were middle- to high-latitudedeciduous trees with roots that were adapted to semi-aquatic conditions (Neish et al., 1993). The presence ofwell-developed growth rings in glossopterid wood fromthe PCMs shows that these plants were also subjected tostrong seasonal variations (McLoughlin et al., 1997;Weaver et al., 1997). The narrow latewood and abruptFig. 6 (contibotany and Palynology 145 (2007) 89122termination of rings suggests that growth of theAntarctic glossopterids was primarily controlled byseasonal photoperiod variation. Despite the fact that theglossopterids were deciduous trees, glossopterid cuti-cles are a relatively rare component in the McKinnonMember palynodebris. The maceral cutinite alsoconstitutes a relatively minor portion (generally b1%)of coals sampled from the Bainmedart Coal Measures(McLoughlin, unpublished data). Glossopterid cuticlenued ).alaeobis typically thin and large sheets are normally difficult toprepare from compressed leaves. Thin and readilydegraded cuticles may be a function of the deciduousnature of glossopterids, the prevailing humid, temperateclimate of the Late Permian, and the plants' affinities formire habitats, hence their little need for cuticularprotection from desiccation. Glossopterids were over-whelmingly the dominant plants in the PCMs during thelatest Permian, and were extremely well adapted to theirenvironment. It seems plausible that other taxa thatdisappeared, or markedly decreased in number, at thePT transition were also adapted to the peat-formingmires in which the glossopterids were the majorconstituents.4.3. Taxa that proliferated after the end-Permian eventThe Ritchie Member palynoflora is also dominatedby gymnospermous pollen, although not to the samedegree as the McKinnon Member. In the RitchieMember, the gymnosperms are represented by peltas-permous or corystospermous bisaccate pollen, such asthe taeniate Lunatisporites spp., Protohaploxypinusmicrocorpus and P. samoilovichii, and the non-taeniateFalcisporites spp. and Alisporites spp. In the lowermostRitchie Member sample (95/01) fern spores assigned toBrevitriletes spp. and Leiotriletes directus (Plate I, a),together with Osmundacidites spp. and Dictyophylli-dites spp., are common, however, all but the last of thesedecrease in abundance in the succeeding samples.Another striking feature of the Ritchie Member palyno-flora is the high diversity and abundance of lycophytespores, mainly Densoisporites, Lundbladispora,Kraeuselisporites and Uvaesporites species. Probablebryophyte spores are minor constituents of the lower-most Ritchie Member assemblage, but increase inabundance in the succeeding samples.The spore/pollen ratio increases dramatically in theRitchie Member indicating that spore-producing plantsplayed a proportionately greater role in the earliestTriassic plant community. This is further indicated bythe dramatic decrease of woody plant debris betweensample 95/04 of the uppermost coal in the McKinnonMember and the lowermost sample of the RitchieMember, 95/01. Non-woody plant remains, includingcuticles, are the most common type of palynodebris inthe Ritchie Member. Lycophyte sporangia and mega-spores are also notably abundant in mesofossil (N200 m)residues from this unit (McLoughlin et al., 1997).From the palynological data it is evident that many ofthe gymnospermous taxa that increase in abundance inS. Lindstrm, S. McLoughlin / Review of Pthe Early Triassic assemblages were already present inlow numbers in the Permian. They appear to haveplayed a subordinate role in the glossopterid-dominatedplant community, perhaps occupying drier sites wheretheir macrofossils were less likely to be preserved.These opportunists proliferated once the glossopteridsand their ecological associates were fading from thescene.So how did the surviving gymnosperms differ fromthose that perished? One of the most abundant pollenspecies in the earliest Triassic of the PCMs is Falcis-porites australis (Plate II, f ). This non-taeniate bisaccatepollen has been found in association with the peltaspermLepidopteris callipteroides (Carpentier) Retallack(2002) (Retallack, 2002), and small pinnules of Lepi-dopteris sp. are prominent in the earliest Triassic samplefrom the PCMs (McLoughlin et al., 1997). Retallack(2002) argued that the thick cuticle, low stomatal indexand small-sized stomata of Early Triassic L. callipter-oides leaves from the Sydney Basin indicated highatmospheric concentrations of CO2. According toRetallack (2002) L. callipteroides migrated southwardsfrom northern Gondwana in the Early Triassic, butcentres of origin and migration pathways are impossibleto determine from the fossil record (Patterson, 1999).Nevertheless, this theory is supported by the recovery ofan Upper Permian Falcisporites-dominated palynofloraand associated Dicroidium fossils in the Dead Searegion in Jordan (Kerp et al., 2006). The Dicroidium-bearing Permian flora of Jordan indicate that corystos-perms developed in the Late Permian in an extrabasinaltropical lowland setting (Kerp et al., 2006). In fact,many of the gymnosperms that played minor rolls in thePermian of Gondwana may have been adapted to betterdrained and perhaps more elevated areas than theglossopterid dominated peat mires that developed in theGondwanan basins. The PCM PermianTriassic suc-cession was deposited within the Lambert Graben,which is suggested to have been fed by a drainagesystem one-fifth the area of East Antarctica (Adamsonand Darragh, 1991). Non-glossopterid gymnospermsmay have been significant components of the vegetationthrough much of this upland region.In the aftermath of the end-Permian crisis, pleur-omeian/isoetalean lycophytes appear to have diversifiedglobally (Pigg, 1992; Kovach and Batten, 1993).Although it is not obvious from the quantitative analy-sis, small percentages of lycophytes (Gondisporitesraniganjensis, Plate I, k; and Indotriradites spp.) arepresent in the McKinnon Member (Fig. 6). However,lycophytes definitely proliferate in the Ritchie Memberwhere, e.g. Densoisporites nejburgii accounts for more105otany and Palynology 145 (2007) 89122than 5% of the assemblage in 95/01.alaeo4.4. Taxa that lingeredSeveral taxa already present, and locally common inthe Permian, appear not to have been greatly affected bythe PermianTriassic crisis. Amongst these are the fernspores Lophotriletes and Osmundacidites. These generahave a slight decline in relative abundance in the EarlyTriassic, but they also vary in representation throughoutthe Late Permian. Leiotriletes directus is another fernspore typically common in the Permian. In theMcKinnon Member this small, laevigate triangularspore is consistently present, but never reaches greaterthan 1.6% of any assemblage. In the lowermost RitchieMember sample it suddenly flourishes constituting 3.8%of the palynoflora, but decreases dramatically in thesucceeding samples. Guttulapollenites hannonicus(Plate I, h; Fig. 8) is another taxon that is traditionallyassociated with the Permian. This gymnosperm pollenrarely reaches 1% in the McKinnon Member, butreaches 1.0 to 2.4% in the Ritchie Member.4.5. ReworkingThe aspect of reworking is critical when analysingtaxon ranges and mass-extinction events based onmicrofossil data. Re-deposition of older material canseverely affect the interpretations of an ecological crisisand its aftermath. As reworked material is quitecommonly encountered in palynological investigations,it is necessary to estimate the degree of reworking in thePCM PermianTriassic transition. In the PCMs, a fewglossopterid pollen and some other typical Permian taxalinger on into the Early Triassic but disappear within afew hundreds of metres above the uppermost coal, e.g.Microbaculispora micronodosa, M. trisina, and M.villosa. It is tempting to suggest that these typicalPermian spores are entirely reworked. However, itshould be noted that they have also been encountered insmall numbers in other Gondwanan Early Triassicsequences (see e.g. de Jersey, 1979). The likelihood ofhaving been reworked is determined by the palynomor-ph's state of preservation, colour, abundance, andassociation with other contemporary taxa. Microbacu-lispora specimens encountered in the Ritchie Membershow no obvious signs of reworking, as they do notdiffer in colour or state of preservation from the rest ofthe palynoassemblage. Quantitatively, they are moreabundant than the few taeniate glossopterid pollen alsopresent in these assemblages. There is no knownPermian assemblage from the PCMs in which Micro-baculispora outnumbers glossopterid pollen (Lind-106 S. Lindstrm, S. McLoughlin / Review of Pstrm, personal observation). If the lower RitchieMember Microbaculispora specimens are reworked,then one would expect to find proportional representa-tion of other typical Permian taxa such as glossopteridpollen. Differential preservation of these groups wasprobably not important because the durability ofglossopterid taeniate pollen is demonstated by the factthat they are amongst the most commonly reworkedpalynomorphs in younger (Late MesozoicCenozoic)strata from Seymour Island, west Antarctica (Askin andElliot, 1982). In the shelf sediments off-shore fromPrydz Bay and the Prince Charles Mountains, Permianpalynomorphs in general are the rarest reworkedelements (Kemp, 1972).4.6. Diversity patternIt is important to remember that fossil spore- andpollen taxa do not necessarily equate to true plant taxa(Lindstrm et al., 1997). Nevertheless, the diversity ofspore-pollen taxa across the PT transition in thePCMs reveals a surprising pattern. The number of taxaregistered in each sample of the McKinnon Membervaries between a minimum of 31 and a maximum of 69(Fig. 6), whereas in the Ritchie Member it varies be-tween 70 and 92. There is a jump in diversity from 66taxa in the last McKinnon Member sample (95/04) to77 taxa in the lowest Ritchie member sample (95/01),and then to a maximum of 92 taxa in the secondRitchie Member sample (95/02). Species diversitydeclines slightly to 71 and 70 taxa respectively in thesucceeding samples (95/07 and 95/05). If expectedoccurrences are taken into account, i.e. the local strati-graphical ranges of the different taxa are used insteadof de facto registrations in each sample, the diversityin the lower and middle parts of the McKinnonmember is very constant, vaying between 81 and 85taxa. In the uppermost part of the McKinnon Memberthere is a drop in diversity to 75 taxa in samples 95/10and 95/08, with a slight increase to 79 taxa in theuppermost McKinnon Member sample (95/04). This isfollowed by a marked increase to 90 taxa in thelowermost Ritchie member sample, with a continuingincrease to 101 taxa in sample 95/02, followed by agradual decrease to 82 and 70 in the two succeedingsamples.Ninety-eight typical Permian taxa are present fromthe lower part of the McKinnon Member, or have beenregistered in the preceeding members. After a stepwiseextinction pattern only 25 of these taxa are present in theuppermost Ritchie Member sample, i.e. only 26% of thetypical Permian taxa survived up to this level in thebotany and Palynology 145 (2007) 89122aftermath of the end-Permian crisis.alaeob4.7. Extinction patternThe extinction pattern of spores and pollen across thePT boundary in the PCMs appears stepwise with amajor extinction between the uppermost coal sample ofthe McKinnon Member and the lowermost RitchieMember sample (Fig. 6). Through most of theMcKinnon Member succession, few taxa have theirlast occurrences (Fig. 6). Exceptions to this patternoccur in the closely spaced samples 95/26B95/29 and95/1195/8. At the lower level, a 10 m interval from1963 to 1973 m, the combined LADs reach almost 11%and the combined FADs are almost 12%, both slightlyhigher than normal. At the higher level, a 5 m intervalfrom 2225 to 2230 m, the combined LADs reach 19%and the combined FADs are only about 1%. However,few of the disappearing taxa at these levels occurregularly or in large numbers within the McKinnonMember, and their last occurrences at a certain level maybe an artifact of incompleteness of the fossil record(Signor and Lipps, 1982). Here, we use the range ex-tension method of Marshall (1995) to test the confidencelevels of the palynostratigraphic ranges across the PTtransition in the PCMs. In accordance with improve-ments by Wang and Marshall (2004), 20% rangeextensions are used, and based on a minimum of fouroccurrence levels throughout the McKinnon and Ritchiemembers only about half of the taxa with LADs withinthis interval can be used. The results alter the stepwiseextinction pattern very little (Fig. 6a, b). None of thetaxa that has its LADs in the interval covering samples95/11, 10 and 08 extends its range up to or above thetopmost McKinnon Member sample (Fig. 6b). Howev-er, for this level the range extensions do show a moregradual extinction pattern stretching over a 25 minterval, than that of the true records. This 95/11 to95/08 interval is taken to represent a first extinctionphase, signalling the initiation of the collapse of theterrestrial ecosystem (Figs. 5a, b and 6a, b). Similarly,none of the taxa that has its LAD in the uppermost coalsample has its range extended up to or beyond thelowermost Ritchie Member sample. The range exten-sions indicate that the taxa with LADs in the uppermostMcKinnon Member sample all disappear within an 8 minterval starting 9 m above the last coal (i.e. between2283 and 2291 m). This is taken to represent the secondand main phase of the end-Permian extinction in thePCMs (Fig. 6a, b). The third extinction phase is repre-sented by the LADs in the lowermost Ritchie Membersample (Fig. 6a, b), the range extensions indicating thatthe taxa disappear within a 7 m interval starting 8 mS. Lindstrm, S. McLoughlin / Review of Pabove the sample level. All but one of the taxa that havetheir LADs in sample 95/02 of the Ritchie Member havetheir ranges extended up to or beyond the next samplelevel. All the taxa with LADs at this level have theirranges extended within a 21 m interval starting 9 mabove sample 95/02. In the next sample, 95/07, none ofthe taxa has its ranges extended up to or above the nextsample level. In fact, all the taxa with LADs at 95/07,except one, have range extensions falling within theupper 8 m of the extension range interval from theprevious sample. The LADs of samples 95/02 and 07 aretaken to represent the fourth extinction phase in thePCMs (Fig. 6a, b).A 20% confidence level used on the FADs of EarlyTriassic taxa, based on a minimum of four occurrencelevels, comprises all the taxa first appearing in thelowermost Ritchie Member sample, and gives a rangeextension downwards to 2286 m. The mean rangeextension level for the LADs in the uppermost coal isalso 2286 m, i.e. the estimated position of the main end-Permian extinction.5. Patterns of change across the PT boundary inGondwana5.1. Sedimentological changes across Gondwanan PTtransitionsThe most apparent lithological and sedimentologicalchange across the PT transition in the PCMs is thecessation of coal (Figs. 2 and 3), and this is also a well-known feature of PT continental boundary strata inseveral other southeastern Gondwana basins, notably theBowen and Sydney basins, Australia and the Transan-tarctic Mountains, central Antarctica (Retallack et al.,1996; Taylor et al., 1989). In India, coals are widelyrepresented in Upper Permian strata but disappearslightly below the PT boundary. Upper Permian coalsare also represented in the eastern Karoo Basin, SouthAfrica, but they were replaced by redbeds well before thePT transition (Ward et al., 2000). The PT boundaryhas been less well studied in South America butuppermost Permian strata of the Parana Basin aredominated by red or varicoloured mudstones with scarceGlossopteris leaves (Rohn and Rsler, 1989).Apart from the disappearance of coal, McLoughlinand Drinnan (1997b) noted that the relative proportion ofsandstone to siltstone increases through the upper part ofthe McKinnon Member and lower part of the RitchieMember in the PCMs. There is a slight change in thedirection of sediment transport across the PT transition;from predominantly N to NE in the McKinnon Member107otany and Palynology 145 (2007) 89122to mainly NW to NNE in the Ritchie Member(McLoughlin and Drinnan, 1997a,b). Sediment cyclicity(fining-up sandstonesiltstonecoal packages) is welldeveloped in the lower members of the Bainmedart CoalMeasures (cycles average ca. 910 m; Fielding andWebb, 1996), but is less well developed and less regularin the McKinnon Member (McLoughlin and Drinnan,1997a). Sediment cyclicity persists in the RitchieMember, but the cycles tend to be thinner (average ca.5.6 m) compared to the preceding Bainmedart CoalMeasures (McLoughlin and Drinnan, 1997b; Holdgateet al., 2005). The changes across the PT transition in thePCMs are interpreted as a shift from large, low-sinuositybraided and minor meandering rivers and poorly drainedforest-mire environments, to medium-sized, low-sinu-osity braided rivers with progressively more episodicdischarge (McLoughlin and Drinnan, 1997a,b).Similar changes in fluvial style across the PermianTriassic transition have been reported from otherGondwana basins. In the Raniganj Basin, India, thePT transition of the Banspetali section shows a drasticsedimentological change (Sarkar et al., 2003). TheUpper Permian Raniganj Formation consists of alter-nating fine- to medium-grained white/grey, plagioclase-rich sandstones, dark organic-rich shales and coal. Thelithologies of the succeeding Lower Triassic PanchetFormation include sandstones rich in unaltered ortho-clase, and grey to olive-green shales. The upper part ofthe Panchet Formation includes reddish strata, and theyare succeeded by the highly immature, poorly sorted,red sandstones and conglomerates of the Supra-PanchetFormation (Sarkar et al., 2003). Tewari (1999) reporteda similar change in fluvial style from Late Permianmeandering river deposits to Early Triassic braidedfluvial sediments in the Godavari Basin, India. Howev-er, there are local discrepancies. In the GAM-7 boreholein the Godavari Basin, the cessation of coals andcarbonaceous shale occurs more than 100 m below thepalynologically defined PT boundary, and is suc-ceeded by greenish gray sandstone and shale (Srivastavaand Jha, 1990).Latest Permian sequences in the Karoo Basin, SouthAfrica lack coal. Instead, the major sedimentological108 S. Lindstrm, S. McLoughlin / Review of Palaeobotany and Palynology 145 (2007) 89122Fig. 7. Composite correlation chart of selected PT transitions across Gondwana.alaeobchange across the PT transition is a rapid, basin-widechange in fluvial style from meandering to braided riversystems (Ward et al., 2000). Below the South African PT boundary, sandstones deposited by large, highsinuosity meandering rivers are interbedded with olivegrey and red mudstones (Ward et al., 2000; Steiner et al.,2003). The PT boundary is associated with a severalmetres thick laminated sandstone-shale unit, under- andoverlain by sandstone and conglomerate (Ward et al.,2000). Above the PT transition, the Karoo Basinsequences are characterized by sediments deposited bybraided river systems. The proportion of sandstone toshale is higher than in the Permian, and the silts andmudstones are predominantly maroon in colour insteadof olive gray (Ward et al., 2000). The drastic change wasinterpreted as indicating increased sedimentation rates inthe earliest Triassic, due to catastrophic die-back of theterrestrial vegetation that would normally preventerosion of river banks and hill slopes (Ward et al., 2000).A similar scenario is reported from the northernBowen Basin in eastern Australia where the PermianTriassic boundary coincides with the lithostratigraphicboundary between the coal-rich Rangal Coal Measuresof the Blackwater Group and the coal-lacking Sagittar-ius Sandstone of the Rewan Group (Michaelsen, 2002).Although palynological data indicates a gradationalfloristic change prior to the boundary, Michaelsen(2002) found no evidence of any lithological changeswithin the Rangal Coal Measures up to the boundary.Instead, a sharp change in the sedimentary regime isevidenced by Late Permian peat mire, sinuous braidedriver channels, extensive crevasse splay, and small lakedeposits abruptly succeeded by high energy, braidedriver sediments in the Early Triassic (Michaelsen, 2002).The PermianTriassic transition in the TransantarcticMountains is also marked by the cessation of coal at or afew metres below the boundary, together with generallythicker packages of trough cross-bedded sandstones inthe Triassic, and major changes in palaeosol composi-tion (Retallack et al., 2005).5.2. Palynofloral turnover in other Gondwanan PTtransitionsAlthough there have been many studies of theGondwanan PT palynofloral transition, they typicallyreport only general paterns of taxon turnover and includevery little or no quantitative palynological data. TheLADs and FADs of selected PT transition taxa in keyGondwanan basins are briefly reviewed here (Fig. 7).Spores and pollen are very poorly preserved in theS. Lindstrm, S. McLoughlin / Review of PPT transitional strata of the Karoo Basin, South Africa(Anderson, 1977). However, Steiner et al. (2003)recently reported a 100% taxonomic turnover in thePermianTriassic Carlton Heights boundary section inthe Karoo Basin. The 1 m thick interval above theboundary is 100% dominated by the putative fungalpalynomorph Reduviasporonites chalastus and woodyplant remains. The assemblage was interpreted torepresent proliferation of fungi upon large quantitiesof decaying plant material (Steiner et al., 2003; Fig. 7).This fungal spike separates 55.5 m of strata assignedto the latest Permian Klausipollenites schaubergeriizone (equivalent to the Australian APP6 or Protoha-ploxypinus microcorpus Zone), from a b0.5 m thickinterval assigned to the Early Triassic Kraeuselispor-itesLunatisporites zone (equivalent of the L. pellucidusZone); these strata succeeded by at least 12 m ofpalynologically barren sandstones (Steiner et al., 2003,Fig. 5). None of the constituents of the Permianpalynoflora in this succession, including Densoispor-ites playfordii, Triplexisporites playfordii and Playfor-diaspora cancellosa was registered above the fungalspike, where instead typical Early Triassic taxa e.g. L.pellucidus, Kraeuselisporites cuspidus, and Lundbla-dispora brevicula were found (Steiner et al., 2003).Despite the apparent high resolution detection of the PTsection at Carlton Heights, some uncertainties remainregarding the palynological signature in the KarooBasin. Palynomorph yields were apparently low andseveral key taxa have patchy records in the range chartsprovided by Steiner et al. (2003). The thick barrenintervals may also preclude identification of the fullranges of key taxa. Furthermore, the fungal spike at theCarlton Heights section is located 17 m above the PTboundary beds as defined by Retallack et al. (2003), andaccording to Ward et al. (2005) well above the top of thePermian based on carbon isotope data. However, itshould be noted that there are several typical Permiantaxa that appear to have their last occurrences between 19and 24 m below the fungal spike zone (Steiner et al.,2003; Fig. 5), possibly corresponding to an initialextinction level.The palynofloristic turnover at the PT transitionwithin the Maji Ya Chumvi Formation, Kenya, ischaracterised by the disappearance of 27% of latestPermian taxa. It is accompanied by a decrease in thenumber of acavate trilete spores, a slight decrease in theabundance of cavate trilete spores, and a major increasein the abundance of taeniate bisaccate pollen (Hankel,1992). The latest Permian assemblage is equivalent tothe Australian APP6 or Protohaploxypinus microcorpusZone, and contains 38% cavate and 32% acavate spores,109otany and Palynology 145 (2007) 8912218% taeniate bisaccate pollen, 7% monosulcate pollenalaeoand only 5% non-taeniate bisaccate pollen (Hankel,1992). It is separated from an earliest Triassic as-semblage by a 24.2 m palynologically barren intervalspanning the PT boundary (Hankel, 1992). The earliestTriassic palynoflora is represented in 18 samples over an8.2 m thick interval and is dominated by taeniate bisac-cate pollen (3756%). Acavate spores are less frequent,832%, and cavate spores vary between 12% and 37%.It was correlated with the Lunatisporites pellucidusZone of Australia (Hankel, 1992). The putative fungalpalynomorph Reduviasporonites chalastus constitutes24% of the latest Permian assemblage and is also presentbut less common (410%) in the earliest Triassic. Lu-natisporites pellucidus first occurs in the earliestTriassic, constituting 59% of the microflora. Amongthe 22 Permian taxa that disappeared at the PTtransition were the important indices P. microcorpus,Lundbladispora willmottii, P. crenulata (Wilson) Foster(1979) and T. playfordii (Hankel, 1992). Of 34 taxaidentified in the younger assemblage, 53% have theirFADs in the earliest Triassic, e.g. D. playfordii andKraeuselisporites cuspidus. However, at least two of thetaxa that last occurred in the Permian (i.e. P. crenula-ta=P. cancellosa and T. playfordii) are present in aneven younger assemblage from the Lower MariakaniFormation (correlated with the Australian P. samoilo-vichii Zone; Hankel, 1991), and could be consideredLazarus taxa (Fig. 7).According to Wright and Askin (1987) theboundary between the Lower and Middle SakamenaGroup in Madagascar approximates the PermianTriassic boundary. The latest Permian palynofloralassemblages are dominated by Guttulapolleniteshannonicus, Weylandites spp. and Lueckisporitesvirkkiae. Glossopterid taeniate bisaccates assigned toProtohaploxypinus and Striatopodocarpidites are gen-erally common. The assemblages include rare speci-mens of Protohaploxypinus microcorpus (Wright andAskin, 1987). Non-taeniate bisaccates are also com-mon and include Platysaccus spp., Alisporites spp.,Falcisporites spp., Scheuringipollenites spp., andKlausipollenites schaubergerii (Wright and Askin,1987). Pteridophyte spores are generally rare. Thefirst occurrence of rare Lunatisporites pellucidus isregistered in the uppermost Lower Sakamena outcropsample (Wright and Askin, 1987). Thirty-five percentof the taxa in this latest Permian assemblage disappearat the PT transition. In contrast, the Early Triassicassemblages are characterised by common to abundantL. pellucidus. Striatopodocarpidites pantii and P.microcorpus increase in abundance. Some typical110 S. Lindstrm, S. McLoughlin / Review of PPermian taxa persist into the lowermost MiddleSakamena, e.g. Densipollenites indicus, Protohaplox-ypinus limpidus, Striatopodocarpidites rarus and G.hannonicus (Wright and Askin, 1987). In the earliestTriassic assemblage 42% of the taxa appear for thefirst time, including Densoisporites playfordii (Fig. 7).A cored section, GAM-7, of the lower and middlemembers of the Kamthi Formation in the GodavariGraben, India, preserves a palynological successionacross the PermianTriassic boundary, listed as assem-blages I to V in ascending order (Srivastava and Jha,1990). The Late Permian assemblages (IIV) aredominated by glossopterid bisaccate pollen, constitutingaround 7050% relative abundance. Other common andimportant taxa are Scheuringipollenites, Densipollenitesand Osmundacidites, whereas Horriditriletes, Lopho-triletes and Weylandites are locally common. BothDensipollenites and Scheuringipollenites have lastappearances in assemblage III. The uppermost Permiancoal seam and carbonaceous shales were recordedwithin the interval associated with assemblage II. Gut-tulapollenites is a rare component in the Permianassemblages, except in IV where it increases to 29%(Srivastava and Jha, 1990). Srivastava and Jha (1990)correlated assemblage IV with the palynoflora from theChhidru Formation of the Salt Range (Balme, 1970) andthe Australian Protohaploxypinus microcorpus Zone(latest Permian), on the basis of the common presence ofi.e. Triquitrites proratus, Playfordiaspora cancellosa,L. noviaulensis, Falcisporites stabilis and P. micro-corpus. Assemblage V, from a sample a little more than12 m above that of assemblage IV (Srivastava and Jha,1990), is correlated with the Lunatisporites pellucidusZone and is dominated by Lunatisporites (32%)including L. pellucidus, and fern spores assigned toVerrucosisporites (10%). Other common elements areLundbladispora, P. cancellosa, Limatulasporites, K.schaubergerii and Alisporites. Glossopterid pollen areapparently still present, but markedly decreased (Fig. 7).Several papers have dealt with the palynology of thePT transition in the Bowen Basin in eastern Australia(e.g. de Jersey, 1979; Foster, 1982), and these werereviewed by Price (1997). In the GSQ Taroom-8 borecore of Denison Trough in the western BowenBasin, the first appearance of Lunatisporites pellucidusis registered about 50 m above the uppermost coal of theBandanna Formation, in the lower part of the RewanGroup (de Jersey, 1979). The earliest Triassic assem-blage is separated from the preceeding productivesample by a ca 42 m barren interval (de Jersey, 1979).Triplexisporites playfordii first appears within a fewmetres above the uppermost coal in the Bandannabotany and Palynology 145 (2007) 89122Formation, thus placing the PT boundary somewherealaeobS. Lindstrm, S. McLoughlin / Review of Pin between the FADs of these two taxa (de Jersey, 1979).Only 4% of the latest Permian taxa disappear by theuppermost Permian sample. However, 25% of taxadisappear by the earliest Triassic assemblage and 19%of taxa are registered for the first time. In nearby GSQSpringsure-1 bore (Fig. 6), L. pellucidus has its FADFig. 8. Palaeobiogeographic distributions of Guttulapollenites hannonPalaeogeographic maps after Scotese (2001). Star denotes presence of tax2. Israel (Eshet, 1990); 3. Argentina (Ottone and Garcia, 1991; Zavattieri an1992); 6. Tanzania (Hankel, 1987); 7. Zimbabwe (Falcon, 1973); 8. South A1993; Wright and Askin, 1987); 10. India, Godavari Graben (Srivastava aTripathi, 1992); 12. Western Australia, Perth and Collie basins (Backhouseunpublished report); 14. East Australia, Bowen Basin (de Jersey, 1979; FosZealand (de Jersey and Raine, 1990); 17. Antarctica, South Victoria Land (Land (Lindstrm, 1996); 19. Antarctica, Prince Charles Mountain (This papUtting, 1997). P. cancellosa has also been registered in the Middle Permia111otany and Palynology 145 (2007) 89122some 12 m above the last coal of the BandannaFormation, just below the boundary between theBandanna Formation and the Rewan Group (de Jersey,1979). This assemblage is separated from the previousproductive sample by a barren interval of ca 11 m, andT. playfordii first appears within the uppermost part oficus, Triplexisporites playfordii and Playfordiaspora cancellosa.on. Localities and occurrences from: 1. Oklahoma (Wilson, 1962);d Batten, 1996); 4. Pakistan (Balme, 1970); 5. Kenya (Hankel, 1991,frica (Anderson, 1977; Steiner et al., 2003); 9. Madagascar (Hankel,nd Jha, 1990); 11. India, Damodar and Rajmahal basins (Tiwari and, 1991, 1993); 13. Western Australia, Bonaparte Basin (Helby, 1977,ter, 1979); 15. East Australia, Sydney Basin (Helby, 1973); 16. NewKyle, 1977; Kyle and Schopf, 1982); 18. Antarctica, Dronning Mauder; McLoughlin et al., 1997); 20. Zambia (Utting, 1979; Nyambe andn of Spain (Broutin, 1986).alaeothe youngest coalseam. In this well, only 4% of thePermian taxa are present for the last time in theuppermost productive sample of the Bandanna Forma-tion. In the earliest Triassic assemblage 19% of the taxaappear for the first time. On the basis of previousstudies, Michaelsen (2002) argued that palynofloralchange across the PT boundary in the Bowen Basin isgradual (Fig. 7) but, as noted above, the significantsampling gap may overlook any dramatic turnover.High-resolution palynological sampling across thePT boundary in the high-palaeolatitude TransantarcticMountains has not yet been undertaken. However,McManus et al. (2002) recently reported sparseglossopterid leaves several metres above the traditionalplacement of the PT boundary at the BuckleyFremouw formation transition. Scattered reports ofsparse earliest Triassic Glossopteris leaves elsewherein Gondwana (Pant and Pant, 1987) are consistent withthe PCM palynological evidence that a few elements ofthe Glossopteris flora persisted into the very earliestTriassic, presumably in isolated humid refugia.5.3. Palaeobiogeographic patternsSeveral taxa show interesting palaeogeographic andbiostratigraphic distributions in the Late Permian andEarly Triassic (Fig. 8). Guttulapollenites hannonicus(Fig. 8) has been registered in Middle to Late Permiansequences from Africa (Anderson, 1977; Falcon, 1973;Utting, 1979), Madagascar (Wright and Askin, 1987),Pakistan (Balme, 1970), India (Srivastava and Jha,1990; Tiwari and Tripathi, 1992; Tiwari, 1999),Antarctica (Balme and Playford, 1967; Lindstrm,1995a, 1996; McLoughlin et al., 1997), and Australia(Backhouse, 1993). In Madagascar (Wright and Askin,1987) and India (Srivastava and Jha, 1990; Tiwari,1999) G. hannonicus is particularly abundant in thelatest Permian. In the PCMs it is a rare but consistentcomponent in the Late Permian, but it is more commonin the Early Triassic, especially in the lowermost RitchieMember sample. There are only two other areas whereG. hannonicus has been recorded in the Early Triassic,namely in the Salt Range of West Pakistan (Balme,1970) and in Madagascar (Wright and Askin, 1987), andtogether with the PCMs these areas appear to have actedas the last refuges for the parent plant of G. hannonicus.In many parts of Gondwana Triplexisporites play-fordii and Playfordiaspora cancellosa occur together(Fig. 8). Both have their FADs in APP6 (latest Permian)microfloras of Australia (Price, 1997), in the earlyChanghsingian uppermost Chhidru Formation in Paki-112 S. Lindstrm, S. McLoughlin / Review of Pstan (Balme, 1970; Foster et al., 1998), and in equivalentmicrofloras in Kenya (Hankel, 1992) and South Africa(Steiner et al., 2003). In India, P. cancellosa is alsoknown from the upper Raniganj Formation (Srivastavaand Jha, 1990; Tiwari and Tripathi, 1992), but T.playfordii first occurs in the Early Triassic (Tiwari andTripathi, 1992). In the PCMs (this paper) and Mada-gascar (Wright and Askin, 1987) T. playfordii and P.cancellosa are not registered in the Late Permian, butfirst appear in the Early Triassic. In South Africa thereare no records of T. playfordii or P. cancellosa in theEarly Triassic (Steiner et al., 2003). In Kenya T.playfordii and P. cancellosa are not recorded in theearliest Triassic assemblages, but reappear in a youngerassemblage (Hankel, 1991, 1992). Triplexisporitesplayfordii shows a similar pattern in Pakistan, whereasP. cancellosa is registered there also in the EarlyTriassic (Balme, 1970). Playfordiaspora cancellosa hasalso been registered in a late Early Triassic assemblagefrom the mid-Zambesi Valley in southern Zambia(Nyambe and Utting, 1997), and in the late MiddleTriassic of Tanzania (Hankel, 1987), and Argentina(Zavattieri and Batten, 1996). In New Zealand T.playfordii and P. cancellosa are first registered in thelate Early Triassic (de Jersey and Raine, 1990), and inSouth Victoria Land both taxa are first registered in theMiddle Triassic (Kyle, 1977).In the Middle to Late Permian both these taxa haveonly been registered outside Gondwana (Fig. 8). Play-fordiaspora cancellosa (or closely related forms) arepresent at locations within 20 of the equator in, e.g.Oklahoma (Wilson, 1962), Southern Europe (Broutin,1986) and Israel (Eshet, 1990), and Triplexisporitesplayfordii in Israel alone situated 20S (Eshet, 1990).The distribution patterns suggest that during the latestPermian both taxa migrated southwards, spreading alonga narrow belt between 65 and 45S ranging from SouthAfrica in the west to eastern Australia (Fig. 8). In theearliest Triassic they both appear to retreat eastwardswith T. playfordii still retaining a very narrow field ofdistribution between 45 and 60S, whereas P. cancel-losa exhibits a wider distibution pattern from 3560S.In the Middle Triassic the distribution patterns forthese taxa expand significantly. Triplexisporites play-fordii then occupied an area stretching from Kenya inthe west to eastern Australia, and between 35 and70S. Playfordiaspora cancellosa had a similar distri-bution pattern in eastern Gondwana, but had also ex-panded its range further westwards to central andsouthern Africa and South America (Fig. 8). Vijaya(1995) also noticed the palaeobiogeographical patternof P. cancellosa and closely related species, suggestingbotany and Palynology 145 (2007) 89122that the parent plant(s) characterized cool climates.alaeobHowever, this study indicates that the parent plant(s)were adapted to perhaps seasonally dry conditions, andthat they migrated southwards during the PermianTriassic as the semi-arid belt continued to expandfurther polewards.In Australia, Triplexisporites playfordii is a consistentand characteristic component of Triassic palynofloras, andit is abundant in the redbeds of both western and easternAustralia (Foster and Archbold, 2001). However, ineastern Australia it is also a common constituent in thelatest Permian coalmeasures (Foster andArchbold, 2001),e.g. in assemblages from the Rangal Coal Measures(Michaelsen et al., 1999; Michaelsen, 2002). Foster andArchbold (2001) suggested that the parent plant of T.playfordii was part of the Late Permian swamp flora.However, the palaeobiogeographical distribution of thistaxon through the Middle Permian to Middle Triassicsuggests that it was adapted to dry conditions, and that itspresence in South Africa, Kenya, Pakistan and Australiaby the latest Permian signals the on-set of drier climate inthose areas.5.4. Contrasting palaeoecological trends across the PTtransitionOne interesting palaeoecological aspect is the quan-titative changes of palynofloral groups across the PTboundary in Gondwana. Some quantitative changes, e.g.the demise of glossopterid pollen, are useful biostrati-graphic and palaeogeographic markers on a regionalscale. But many other quantitative changes are promi-nent only locally, as they mirror narrow geographicenvironmental and climatic changes. The Late Permianassemblages of the PCMs, overwhelmingly dominatedby glossopterid gymnosperms, were replaced in theEarly Triassic by assemblages containing higher propor-tions of spores from ferns and lycophytes. The exactopposite scenario occurred in Kenya where the latestPermian assemblage is dominated by acavate and cavatetrilete spores, and the Early Triassic palynoflora isenriched in taeniate (although non-glossopterid) bisac-cate pollen (Hankel, 1992). In terrestrial PT boundarysections in South China, spores are also dominant (85%relative abundance) in the latest Permian assemblageswhereas in the earliest Triassic gymnospermous pollenare most abundant with 60% (Peng et al., 2005, in press).5.5. 13C signal across the PT transitionIn terrestrial PT sections from Gondwana there arediscrepancies between the palynologically inferred PTS. Lindstrm, S. McLoughlin / Review of Pboundary and the negative 13C excursion that is com-monly used as a proxy for the boundary in the absence ofbiostratigraphic or radiometric data. 13C analyses fromthe Bowen Basin, Australia, show a negative shift withinthe Protohaploxypinus microcorpus Zone or APP6, butwith maximum negative values within the lowermost partof the Lunatisporites pellucidus Zone or APT1 (Morante,1996; Hansen et al., 2000). In Madagascar, de Wit et al.(2002) recorded a sharp negative 13C spike a few metresabove the palynologically defined PT boundary in theMorondava Basin, but also showed that the negativeexcursion began some 8 m below the boundary. In theBanspetali section in the Raniganj Basin, India, where theuppermost Permian coal seam occurs ca 17 m below thepalynologically defined PT boundary, Sarkar et al.(2003) reported a 9 drop in organic carbon 13C 8 mabove the palynologically inferred PT boundary.However, in the GAM-7 borehole from Godavari Basinde Wit et al. (2002) found a large sharp negative 13Cspike of8 ca 10m below the palynologically inferredPT boundary as defined by the FAD of L. pellucidus,followed by a sharp reversal of14. The large negativespike is preceeded by a weak negative trend that appearsto start some 85 m below the boundary. In the GAM-7borehole, the cessation of strata containing coal and car-bonaceous shale occurs a little more than 100m below thePT boundary (Srivastava and Jha, 1990).No 13C analyses were carried out on the CarltonHeights section in South Africa but at Bethulie, also inthe Karoo Basin, the initial negative 13C excursioncoincides with the first occurrence of Lystrosaurus at thebase of the laminated maroon mudstone beds (MacLeodet al., 2000; Smith and Ward, 2001; Steiner et al., 2003).According to Steiner et al. (2003) this equates to 20 mbelow the fungal spike layer at Carlton Heights, but 17 mbelow according to Retallack et al. (2003). No 13Cvalues are yet available from the PCM succession.The primary source of the organic matter has a stronginfluence on the isotopic values of organic carbon(Foster et al., 1997). Wood-derived kerogen is isotopi-cally heavier (24) than an assemblage dominated byspinose acritarchs (30), so bulk analyses of organicshale rich in wood debris always yield isotopically lightsignatures (Foster et al., 1997). This emphasises theimportance of conducting throrough palynological andpalynofacies studies on the same samples from whichbulk 13Corg analyses are carried out.5.6. PT Gondwanan palaeogeography, sea levels andpalaeoclimatePalaeogeographic reconstructions of Pangea place113otany and Palynology 145 (2007) 89122the Prince Charles Mountains at 60S around 250 Maalaeo(Torsvik and Van der Voo, 2002), more or less at thecentre of the Gondwanan part of Pangea. The samepalaeogeographic reconstructions place the BowenBasin at 6065S, Karoo Basin at 6050S, Kenyaand Madagascar around 5040S, and the IndianGodavari and Son-Mahanadi Basins at 55S.During the Middle to Late Permian a gradual warm-ing trend is evident from the western to the eastern partsof Gondwana. In southern and central Africa, coaldeposition ended during the Middle Permian (Cairn-cross, 2001), and warm, semi-arid conditions reignedfrom the Capitanian (Visser, 1995). A gradual warmingtrend through the Permian is also evident by the re-duction in ice-rafted dropstones and other cryogenicfeatures in eastern Australian basins (Draper, 1983). Thedecline in number and thickness of coal seams in thePCMs, together with increasing ratios of silica andaluminium oxides in the uppermost coals, suggestincreased weathering and climatic drying towards theend of the Permian (Holdgate et al., 2005).The Late Permian coals in the PCMs were depositedduring consistently moist and cool conditions under astrongly seasonal light regime (Weaver et al., 1997;McLoughlin and Drinnan, 1997a). Similarly, coal depo-sition continued more or less to the end of the Permian inthe Perth, Bowen, and Sydney basins. High-latitude coalforest swamps developed in Gondwana during the LatePermian due to global warming. However, by the end ofthe Permian the intensifying greenhouse conditions incombination with the strongly seasonal light regimecould no longer sustain the remaining coal forest swampseven in polar latitudes (Kidder and Worsley, 2004).Although the end-Permian has traditionally beenconsidered to correspond to a major sea-level lowstand(Hallam, 1984; Ross and Ross, 1987), Hallam andWignall (1999) claimed that the PT boundary corre-sponds to a phase of rising sea levels. Most Gondwanabasins are characterized by continental sediments in thelatest Permian, which favours the traditional eustaticmodels. However, there is widespread evidence formarine transgression in the Early Triassic (Wignall et al.,1996). Marine spinose acritarchs, mainly Veryhachiumand Micrhystridium spp., have been encountered inEarly Triassic assemblages from Pakistan (Balme,1970), Madagascar (Wright and Askin, 1987; Hankel,1993), and Western Australia (Dolby and Balme, 1976;Thomas et al., 2004). The earliest Triassic oil sourcerocks (Kockatea Shale) in the Perth Basin were depositedduring a transgressive phase, either under stronglyanoxic conditions, or as a result of coastal upwelling,and which lasted until the Dienerian, i.e. upper Induan114 S. Lindstrm, S. McLoughlin / Review of P(Thomas et al., 2004). The basal beds of the KockateaShale are characterized by a very low diversity marinefauna and extensive stromatolitic layers. Tripathi (1997)recorded marine acritarchs in the latest Permian of SouthRewa, Rajmahal and Damodar basins, and in the earliestTriassic of South Rewa and Damodar basins. Followingthe model proposed by Harrowfield et al. (2005), marineinundation in the Early Triassic may have extended deepinto the supercontinent along a pre-existing (Permian)intra-Gondwanan rift. An accurate eustatic signal may bedifficult to resolve in the absence of a well-developed,tectonically undisturbed passive margin succession inGondwana.The Early Triassic climate of the PCMs was less sea-sonal with increasing aridity as indicated by the initiationof red-bed deposition (McLoughlin and Drinnan, 1997b;McLoughlin et al., 1997). However, Retallack et al.(2003) argued that the increased ratio of alumina in theEarly Triassic palaeosols compared to those of thePermian, and variations in distribution of calcareousnodules in the palaeosols indicate that the Early Triassicclimate of the Karoo Basin was less seasonal, and morehumid (semi-arid to sub-humid) than the stronglyseasonal arid palaeoclimate of the Late Permian.It appears that the humid and strongly seasonal areas tothe east became drier and less seasonal across the PTtransition, while the arid and strongly seasonal regions tothe west also became less seasonal, but more humid. Thus,in the aftermath of the end-Permian event a generallywarmer and less seasonal climate appears to have prevailedin southern Gondwana than during the Late Permian.6. Implications for possible causes of the end-PermianextinctionThe cause of the end-Permian extinction event isconjectural; proposed scenarios including 1) an asteroidimpact (Basu et al., 2003; Becker et al., 2004), 2) floodbasalt volcanism (Renne et al., 1995; Courtillot andRenne, 2003), 3) release of methane from clathrates(Ryskin, 2003), and most recently 4) extreme globalwarming during the Permian initiated by the waning ofthe Alleghenian/Variscan/Hercynian orogeny and fur-ther intensified by 2) and 3) (Kidder andWorsley, 2004).Two large pulses of continental flood basalts occurred inthe latest Permian: the Emeishan basalts in South Chinathat appear to be synchronous with the end-Guadalupianextinction (Lo et al., 2002), and emplacement of theSiberian Traps was coeval with the end-Permian ex-tinction (Mundil et al., 2004).Ecosystem recovery after the end-Permian extinction isknown to have been unusually slow, with a duration atbotany and Palynology 145 (2007) 89122least twice those following other major extinctionsalaeob(Hallam, 1991; Erwin, 1998a,b). Several large fluctuationsof both organic and carbonate 13C occurred during theEarly Triassic (MacLeod et al., 2000; de Wit et al., 2002;Payne et al., 2004). These perturbations may in part belinked to release of volcanigenic CO2 or methane hydratesbut they may also incorporate a biological signature. Asglobal marine biodiversity first began to rise in theSmithian, i.e. early Olenekian (Payne et al., 2004), thesefluctuations coincided with the prolonged marine ecosys-tem recovery after the end-Permian crisis.The PCM palynological record indicates that thecollapse of the terrestrial ecosystem was initiated alreadyprior to the deposition of the last coal. A first extinctionphase can be recognized within a 5 m interval starting49m below the last coal. Themajor extinction in the latestPermian is directly associated with the last coal, and wasfollowed by continued stepwise extinction over a strati-graphic interval of 85 m. Using the calculated averagesedimentation rate for the Ritchie Member of 261 m/Mathe extinction event may have lasted ca 325000 yearsalthough high-resolution sampling will be necessary toconstrain the finer details of floristic turnover. The PCMdata also show a similar stepwise floristic recovery of theterrestrial ecosystem, where each level of extinction cor-responds to the appearance of a suite of new taxa. Theincrease in spore-pollen diversity in the Early Triassic ofthe PCMs is, thus, a direct effect of continued stepwiseextinction offset by simultaneous floristic recovery. Thesestepwise changes in the flora are consistent with theturnover of terrestrial vertebrates through the PermianTriassic transition in the Karoo Basin, South Africa,reported by Smith and Botha (2005).The environmental changes that took place at the endof the Permian were dramatic enough to eliminate theglossopterid dominated ecosystem of southern Gond-wana. In high latitude areas above 60S, such as the PCMsand Bowen Basin, coal deposition continued throughoutthe Late Permian, while in other areas to the west andnorth coal deposition ceased earlier. This supports thetheory that extreme global warming was occurring duringthe Permian. Stepwise extinction of taxa typically asso-ciated with the glossopterid flora continued for a shortinterval beyond the initial biotic crisis. Contemporaneousstepwise introduction of new taxa, and Gondwana-widere-organisation of the terrestrial ecosystem show that theeffects of the end-Permian crisis were continuing to affectthe biota at least until the Olenekian.7. ConclusionsAll samples from the McKinnon Member of theS. Lindstrm, S. McLoughlin / Review of PBainmedart Coal Measures, Prince Charles Mountains,including one from the uppermost coalseam (repre-senting the top of the member), yielded typical LatePermian assemblages dominated by glossopterid pol-len. There are minor quantitative variations in thepalynoflora, but the samples contain essentially equiv-alent assemblages demonstrating that the Late Permianterrestrial ecosystem was quite stable in this area. Thesample from the uppermost coal seam yielded the lasttypically Permian glossopterid-dominated palynoflora.The succeeding sample, collected from the lowerRitche Member of the Flagstone Bench Formation,24 m above the uppermost coal, contains a fundamen-tally different palynoflora of earliest Triassic aspectdemonstrating that the terrestrial ecosystem underwenta dramatic change through that interval. However,rather than a simple abrupt turnover, it is evident thatthe immediate post-crisis phase was a period of con-stant floristic change. After the disappearance of a largenumber (33%) of typical Permian taxa, an initialincrease in diversity of taxa of earliest Triassic aspectoccurred simultaneously with continued extinction oflingering Permian taxa. Only later in the Early Triassicdo diversity levels appear to become more constant asthe number of FADs decrease. A similar initialdiversity increase instead of a decrease was also de-scribed by Looy et al. (2001) from East Greenland. Inthe aftermath of the end-Permian crisis only 26% of thetypical Permian taxa present from the lower McKinnonMember appear to have survived until late Induan times.The average sedimentation rate indicates that the extinc-tion event lasted ca 325000 years. This can be comparedwith the vertebrate extinction data for the Karoo Basin,which show that 69% of the vertebrate fauna disappearedover a period of 300000 years, followed by a lesserextinction phase wiping out the remaining 31%160000 years later (Smith and Botha, 2005).The palynological pattern is matched by thesedimentological record of the PCMs. Coal seamsshow gradual diminution in thickness and spacingbelow the PermianTriassic transition, unlike thatreported from the Bowen Basin (Michaelsen, 2002).The immediately overlying succession is dominated bythick sandstone packages interspersed with sparsecarbonaceous shales. Higher in the Lower Triassicsuccession carbonaceous beds disappear and arereplaced by thin red or mottled shales. Contemporane-ous changes in fluvial style from meandering rivers orcoal-rich braided systems, to braided river systems withepisodic discharge have been recorded in differentGondwanan basins across the PT transition, and havebeen attributed to increased sediment load due to loss of115otany and Palynology 145 (2007) 89122vegetation cover.alaeoComparisons of the palynology of PT transitionsfrom different parts of Gondwana also show that therewere major differences in the composition of the re-gional palynofloras in the latest Permian, but that thesebecame more similar following the initial biotic crisis. Inhumid areas, e.g. the PCMs, gymnospermous pollenwere overwhelmingly dominant in the latest Permian,and following the mass-extinction lycophyte sporesproliferated. In semi-arid areas, e.g. Kenya, lycophytespores were already prominent constituents of the latestPermian palynoflora. Instead, gymnosperms becamemore dominant after the initial crisis. Humid areas be-came drier and at least some dry areas more humid. ThisGondwana-wide re-organisation of the terrestrial eco-system indicates that dramatic changes of the atmo-spheric cells took place during the latest Permian toearliest Triassic, as suggested by Kidder and Worsley(2004). In the terrestrial setting this resulted in ap-parently more equable, sub-humid to semi-arid condi-tions across southern Gondwana.The 24 m sampling gap between the uppermostBainmedart Coal Measures sample and the lowermostFlagstone Bench Formation sample in the PCMscurrently prohibits analysis of the short term changesassociated with the end-Permian extinction. However,the palynological record from the PCMs shows that afterthe end-Permian crisis the terrestrial ecosystem wasalready on its way to recovery in the Induan.AcknowledgementsThis study was funded by a Swedish ResearchCouncil grant to SL and an Australian Research CouncilAustralian Research Fellowship to SM. The AustralianAntarctic Division provided financial and logisticalsupport during the expedition to Prince Charles Moun-tains during the Austral summer of 19941995. EditorHenk Visscher and the reviewers John Backhouse andClinton B. Foster are gratefully acknowledged for val-uable comments that improved the manuscript.Appendix A. Alphabetical list of taxa identified inthis studyAlisporites asansolensis Maheshwari and Banerji1975Alisporites splendens (Leschik) Foster, 1979Alisporites tenuicorpus Balme, 1970Alisporites spp.Apiculatisporis clematisi de Jersey, 1968Aratrisporites spp.116 S. Lindstrm, S. McLoughlin / Review of PBaculate sporomorph indet.Baculatisporites bharadwaji Hart, 1963Baculatisporites spp.Barakarites rotatus (Balme and Hennelly) Bharad-waj and Tiwari, 1964Bascanisporites undosus Balme and Hennelly 1956Botryococcus sp.Brazilea scissa (Balme and Hennelly) Foster, 1975Brevitriletes hennellyi Foster, 1979Brevitriletes levis (Balme and Hennelly) Bharadwajand Srivastava 1969Calamospora tener (Leschik) de Jersey 1962Camptotriletes warchianus Balme 1970Cannanoropollis bilateralis (Tiwari) Lindstrm, 1995Cannanoropollis janakii Potoni and Sah, 1960Chordasporites australiensis de Jersey, 1962Circulisporites parvus de Jersey, 1962Clavatisporites spp.Concavissimisporites grumulus Foster, 1979Converrucosisporites cameronii (de Jersey) Playfordand Dettmann, 1965Converrucosiporites sp. AConverrucosisporites spp.Convolutispora spp.Corisaccites alutas Venkatachala and Kar, 1966Crustaesporites spp.Cycadopites follicularis Wilson and Webster, 1946Cyclogranisporites sp. ACyclogranisporites spp.Deltoidospora australis (Couper) Pocock, 1970Deltoidospora breviradiatus (Helby)Densipollenites indicus Bharadwaj, 1962D. invisus Bharadwaj and Salujha, 1964Densoisporites complicatus Balme 1970Densoisporites nejburghii (Schulz) Balme 1970Densoisporites playfordii (Balme) Dettmann, 1963Densoisporites psilatus (de Jersey) Raine and deJersey in Raine et al. 1988Dictyophyllidites mortonii (de Jersey) Playford andDettmann, 1965Dictyotidium spp.Dictyotriletes sp. ADidecitriletes ericianus (Balme and Hennlly) Venka-tachala and Kar, 1965Didecitriletes uncinatus (Balme and Hennelly)Venkatachala and Kar, 1965Distriatites dettmannae (Segroves) Foster, 1979Distriatites insolitus Bharadwaj and Salujha, 1964Dulhuntyispora granulata Price, 1983Ellipsovelatisporites sp.Enzonalasporites vigens Leschik, 1955Ephedripites sp. (large)botany and Palynology 145 (2007) 89122Equisetosporites steevesiae (Jansonius) de Jersey, 1962alaeobFalcisporites australis (de Jersey) Stevens, 1981Falcisporites stabilis Balme 1970Florinites eremus Balme and Hennelly, 1955Fungal hyphae cf. Palaeancistrus spp.Gnetaceaepollenites bulbiger Anderson 1977Gondisporites raniganjensis Bharadwaj, 1962Gondisporites sp. AGoubinispora morondavensis (Goubin) Tiwari andRana, 1981Granulatisporites absonus Foster, 1979Granulatisporites sp.Grebespora concentrica Jansonius, 1962Guttatisporites sp.Guttulapollenites hannonicus Goubin, 1965Horriditriletes filiformis (Balme and Hennelly)Backhouse 1991Horriditriletes ramosus (Balme and Hennelly) Bhar-adwaj and Salujha 1964Horriditriletes tereteangulatus (Balme and Hen-nelly) Backhouse 1991Inaperturopollenites nebulosus Balme 1970Inaperturopollenites sp.Indospora clara Bharadwaj, 1962Indospora laevigata Bharadwaj and Salujha emend.Foster, 1979Indotriradites niger (Segroves) Backhouse 1991Indotriradites rallus (Balme) Foster 1979Indotriradites sp. cf. I. reidii Foster, 1979Interradispora daedala Foster, 1979Interradispora versus Price, 1979Klausipollenites schaubergeri (Potoni and Klaus)Jansonius, 1962Klausipollenites sp. AKraeuselisporites cuspidus Balme, 1963Kraeuselisporites saeptatus Balme, 1963Kraeuselisporites verrucifer de Jersey and Hamilton,1967Kraeuselisporites spp.Leiotriletes virkkii Tiwari, 1965Laevigate sporomorph indet.Laevigatosporites colliensis (Balme and Hennelly)Venkatachala and Kar, 1968Laevigatosporites spp.Leiotriletes directus Balme and Hennelly, 1955Limatulasporites fossulatus (Balme) Helby andFoster 1979 in Foster, 1979L. limatulus (Balme) Helby and Foster, 1979 inFoster, 1979Lophotriletes novicus Singh, 1964Lueckisporites virkkiae Potoni and Klaus, 1954Lueckisporites spp.Lunatisporites acutus Leschik, 1955S. Lindstrm, S. McLoughlin / Review of PLunatisporites noviaulensis (Leschik) Foster, 1979L. sp. cf. L. noviaulensis (Leschik) Foster, 1979Lunatisporites obex (Balme) de Jersey 1979Lunatisporites pellucidus (Goubin) Helby, 1972Lunatisporites spp.Lundbladispora brevicula Balme, 1963Lundbladispora willmottii Balme, 1963Lundbladispora spp.Maculatasporites spp.Marsupipollenites striatus (Balme and Hennelly)Foster, 1979Marsupipollenites triradiatus Balme and Hennelly,1956Mehlisphaeridium regulare Anderson 1977Microbaculispora micronodosa (Balme and Hen-nelly) Anderson 1977Microbaculispora tentula Tiwari, 1965Microbaculispora trisina (Balme and Hennelly)Anderson 1977Microbaculispora villosa (Balme and Hennelly)Bharadwaj, 1962Minutosaccus sp.Monosulcites spp.Osmundacidites fissus (Leschik) Playford, 1965Osmundacidites senectus Balme, 1963Osmundacidites wellmanii Couper, 1953Ovalipollis Ovalipollis sp.Peltacystia monile Balme and Segroves, 1966Peltacystia venosa Balme and Segroves 1966Platysaccus leschikii Hart, 1960Platysaccus queenslandi de Jersey, 1962Platysaccus spp.Playfordiaspora cancellosa (Playford and Dettmann)Maheshwari and Banerji, 1975Polypodiidites sp. sensu Balme 1970Polypodiisporites mutabilis Balme 1970Potonieisporites balmei (Hart) Segroves, 1969Potonieisporites novicus Bharadwaj, 1954Praecolpatites sinuosus (Balme and Hennelly)Bharadwaj and Srivastava, 1969Protohaploxypinus amplus (Balme and Hennelly)Hart, 1964P. bharadwajii Foster, 1979Protohaploxypinus jacobii (Jansonius) Hart, 1964Protohaploxypinus limpidus (Balme and Hennelly)Balme and Playford 1967Protohaploxypinus microcorpus (Schaarschmidt)Clarke, 1965P. pennatulus (Andreyeva) Hart, 1964Protohaploxypinus perexiguus (Bharadwaj and Salu-jha) Foster, 1979117otany and Palynology 145 (2007) 89122Protohaploxypinus rugatus Segroves, 1969alaeoProtohaploxypinus samoilovichii (Jansonius) Hart,1964Protohaploxypinus spp.Pteruchipollenites gracilis (Segroves) Foster, 1979Punctatisporites fungosus Balme, 1963Punctatisporites spp.Punctatosporites walkomii de Jersey, 1962Punctatosporites sp.Quadrisporites horridus Hennelly ex Potoni andLele, 1961Reduviasporonites chalastus (Foster) Elsik, 1999Retusotriletes clipeata Helby, 1966Retusotriletes junior de Jersey and Hamilton, 1967Retusotriletes nigritellus (Luber) Foster, 1979Retusotriletes radiatus sensu Helby 1973Rewanispora foveolata de Jersey, 1970Rugulatisporites trisinus de Jersey and Hamilton,1967Remarks: Specimens herein assigned to R. trisinusdiffer slightly from the figured holotype in that therugulate ornamentation is generally somewhat denser andfiner, but they still conform with the original descriptionfor the species.Rugulatisporites spp.Sahnites sp.Scheuringipollenites maximus (Hart) Tiwari, 1973Scheuringipollenites ovatus (Balme and Hennelly)Foster, 1975Schizopollis disaccoides Venkatachala and Kar, 1964Schizopollis woodhousei Venkatachala and Kar,1964Semiretisporis sp. cf. S. denmeadii (de Jersey) deJersey, 1970Small scabrate thin-walled sporomorphs indet.Spinate sporomorph indet.Striatoabieites multistriatus (Balme and Hennelly)Hart, 1964Striatopodocarpidites cancellatus (Balme and Hen-nelly) Hart, 1964Striatopodocarpidites fusus (Balme and Hennelly)Potoni, 1956S. rarus (Bharadwaj and Salujha) Balme 1970Striatopodocarpidites solitus (Bharadwaj and Salu-jha) Foster, 1979Striatopodocarpidites spp.Striomonosaccites brevis Bose and Kar, 1966Striomonosaccites sp.Sulcosaccispora alaticonformis (Malyavkina) deJersey, 1968Tetraporina tetragona (Pant and Mehtra) Anderson1977118 S. Lindstrm, S. McLoughlin / Review of PThick-walled rugulate/scabrate sporomorphs indet.Thymospora cicatricosa (Balme and Hennelly) Hart,1965Triadispora sp. cf. T. epigona Klaus, 1964Triplexisporites playfordii (de Jersey and Hamilton)Foster, 1979Triquitrites proratus Balme 1970Tuberculatosporites aberdarensis de Jersey, 1962Uvaesporites verrucosus (de Jersey) Helby in deJersey, 1971Uvaesporites sp.Verrucosisporites surangei Maheshwari and Banerji,1975Verrucosisporites sp. cf. V. trisecatus Balme andHennelly, 1956Verrucosisporites spp.Vitreisporites bjuvensis Nilsson, 1958Vitreisporites pallidus (Reissinger) Nilsson, 1958Weylandites lucifer (Bharadwaj and Salujha) Foster,1975Weylandites magmus (Bose and Kar) Backhouse1991ReferencesAdamson, D., Darragh, A., 1991. Field evidence on Cainozoic historyand landforms in the northern Prince Charles Mountains, EastAntarctica. In: Gillieson, D., Fitzsimons, S. (Eds.), QuaternaryResearch in Australian Antarctica: Future Directions. SpecialPublication, vol. 3. Department of Geography and Oceanography,University College, The Australian Defence Force Academy,Canberra, pp. 514.Anderson, J.M., 1977. 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McLoughlin / Review of Palaeobotany and Palynology 145 (2007) 89122Synchronous palynofloristic extinction and recovery after the end-Permian event in the Prince C.....IntroductionGeological setting and lithostratigraphyTectonic settingLatest Permian McKinnon MemberLatest Permian to earliest Triassic Ritchie MemberPalynological investigationMaterials and methodsPalynostratigraphySedimentation ratePalynofloral turnoverThe Late Permian stable ecosystemThe end-Permian crisis and the taxa that perishedTaxa that proliferated after the end-Permian eventTaxa that lingeredReworkingDiversity patternExtinction patternPatterns of change across the PT boundary in GondwanaSedimentological changes across Gondwanan PT transitionsPalynofloral turnover in other Gondwanan PT transitionsPalaeobiogeographic patternsContrasting palaeoecological trends across the PT transition13C signal across the PT transitionPT Gondwanan palaeogeography, sea levels and palaeoclimateImplications for possible causes of the end-Permian extinctionConclusionsAcknowledgementsAlphabetical list of taxa identified in this studyReferences


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