Note on glauconitic sandstones in the Wairarapa, New Zealand

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  • This article was downloaded by: [Stony Brook University]On: 29 October 2014, At: 04:55Publisher: Taylor & FrancisInforma Ltd Registered in England and Wales Registered Number: 1072954Registered office: Mortimer House, 37-41 Mortimer Street, London W1T 3JH,UK

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    Note on glauconitic sandstonesin the Wairarapa, New ZealandB.D. Webby a c & H.B. Van Den Heuvel ba New Zealand Geological Survey , Christchurchb Mount Isa Mines Ltd. , Mount Isa , Queenslandc Department of Geology and Geophysics ,University of Sydney , AustraliaPublished online: 09 Feb 2012.

    To cite this article: B.D. Webby & H.B. Van Den Heuvel (1965) Note on glauconiticsandstones in the Wairarapa, New Zealand, New Zealand Journal of Geology andGeophysics, 8:1, 81-84, DOI: 10.1080/00288306.1965.10422132

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  • 1965J

    NOTE ON GLAUCONITIC SANDSTONES IN THE W AIRARAPA, NEW ZEALAND

    B. D. WEBBY

    New Zealand Geological Survey, Christchurch*

    and

    H. B. VAN DEN HEUVEL

    Mount Isa Mines Ltd., Mount Isa, Queensland

    (ReceilJed for publication, 18 October 1963)

    ABSTRACT

    81

    Cretace()us-Tertiary glauconitic sandstones near Flat Point, showing moderate to poor graded bedding, lamination, cross lamination, and flute marks, are tentatively considered (0 be turbidity-current deposits. These rocks contain an abundance of worm burrowing' and tracks.

    Upper Cretaceous to Lower Tertiary glauconitic sandstones, with flute marks (Craig and Walton, 1962) on their undersurfaces, have been observed in the Wairarapa at three localities near Flat Poin.t (Fig. 1). The geology of this area has been described previously by van den Heuvel (1960). In the middle branch of the Huatokitoki Stream (N166/342252), bedded glauconitic sandstones within the Kaiwhata Limestone (Waipawan-Mangaorapan) show well-developed flute marks (Fig. 2), cross lamination, moderate grading, and abundant worm tracks and burrowings, frequently seen to cut sedimentary laminae. The flute marks indicate that the currents flowed in a northerly direction. In the second locality, in the upper reaches of the eastern branch of Arawhata Stream (N162/355308), glauconitic sandstones are interbedded in the Whangai Shale (Haumurian-Teurian). The glauconitic sandstones are evenly bedded, usually about 1 ft thick, but show only moderate grading. Well developed lamination and cross lamination arc shown in the upper part of beds, and abundant flute marks and worm tracks on the under-surfaces. Thirdly, in the middle branch of the Arawhata Stream (N166/360285), there are alternating glauconitic sandstones and light green mudstones interbedded with dark grey, reddish-brown and light green bentonitic mudstones, probably Heretaungan-Porangan in age. The glauconitic sandstones show flute marks and worm tracks on their soles, but are poorly graded. A sandstone sample, sectioned in the plane of bedding, revealed a grain-alignment parallel to the flute marks.

    * Present address: Department of Geology and Geophysics, University of Sydney, Australia.

    N.Z. J. Geol. Geoflhys. 8 : 81-4

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  • 82

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    N.z. JOURNAL OF GEOLOGY AND GEOPHYSICS

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    FIG. I-Map showing glauconitic sandstone localities in the Flat Point area: (1) Huatokitoki Stream; (2) eastern branch, and (3) middle branch of the Arawhata Stream.

    Sedimentation of glauconitic sandstones has generally been attributed to ordinary current deposition under the specialised conditions needed for the formation of glauconite* and, occasionally, under less specialised con-ditions in which the glauconite has been reworked and transported. How-ever, Waterhouse and Bradley (1957, p. 528) have recently suggested that the glauconitic sandstones interbedded in the Mungaroa Limestone of the south-eastern Wairarapa (probably correlative with the Kaiwhata Limestone) may be turbidity-current deposits. They indicated that the glauconite formed on actively growing anticlinal highs within the sedimentary basin, and periodically slumped off in turbid flows into adjacent troughs. This hypo-thesis seems to explain satisfactorily the two contrasting types of sedimenta-tion within the same sedimentary basin-namely, slow sedimentation enabling the formation of glauconite, and periodic, rapid influxes of material by turbidity currents. The glauconitic sandstones near Flat Point occur as incidental intercalations at three different stratigraphic levels-

    *As outlined by Cloud (1955), the physical requirements for the origin of glauconite are: (1) marine water of normal salinity, (2) slightly reducing conditions in the presence of organic matter, (3) appropriate source materials, (4) moderately shallow water, and (5) slow sedimentation

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  • 1965] WEBBY & VAN DEN HEU VEL ~ W AIR ARAP A S AN DSTONE 83

    FIG. 2-Flute marks and worm tracks on the under-surface of a glauconitic sand-stone bed in Huatokitoki Stream. N ote the worm tracks radia ting from a worm burrow ( ?} near the bottom centre of the figure , and also the prominent open joints. The current producing the flute marks flowed frorv left to right (south to north).

    within the Whangai Shale, within the Kaiwhata Limestone, and in a sequence of mudstones and bentonitic mudstones. Each set of intercalations may represent a sudden influx of turbidite deposits from an adjacent anticlinal high following a period of tectonic activity.

    In addition to the Wairarapa occurrences, Stoneley (1962, p. 632) has mentioned thin glauconitic sandstones in the Lower Tertiary succession near Gisborne, which show evidence of turbidity currents . Also, Dzulynski, Ksi~zkiewicz, and Kuenen (1959) have reported glauconitic sandstones of turbidite origin in the Lower Tertiary of the Polish Carpathians and, from Bavaria, glauconite in quartzitic beds within Cretaceous flysch, which also appears to have a turbidite origin.

    Although the sedimentary features in the Flat Point glauconitic sand-stones favour interpretation as turbidites, recent work has shown that graded bedding is the only sedimentary structure that provides a valid criterion for distinguishing turbidites and non-turbidites, and the presence of Rute marks is not necessarily diagnostic of turbidites (Murphy and Schlanger, 1962; Dott, 1963) . Obviously more work is needed on these highly interesting sediments, especially on the petrography, before firm conclusions on their origin can be reached. In the meantime, the Flat Point glauconitic sandstones may be tentatively regarded as turbidites.

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  • 84 N.Z. JOURNAL OF GEOLOGY AND GEOPHYSICS [FEB.

    REFERENCES

    CLOUD, P. E. 1955: Physical Limits of Glauconite Formation. Bull. Amer. As.roc. Petrol. Ceol. 39: 484-92.

    CRAIG, G. Y.; WALTON, E. K. 1962: Sedimentary Structures and Palaeocurrent Directions from the Silurian Rocks of Kirkcudbrightshire. Trans. Edinb. Ceol. Soc. 19: 100-19, pIs. 3-6.

    DOTT, R. H. 1963: Dynamics of Subaqueous Gravity Depositional Processes. Bull. Amer. Assoc. Petro!. Ceol. 47: 104-2g.

    DZUl.yNSKI, S.; KSI4ZKIEWICZ, M.; KUENEN, PH. H. 1959: Turbidites in Flysch of the Polish Carpathian Mountains. Bull. Ceol. Soc. Amer. 70: 1089-118.

    HEUVEL, H. B. VAN DEN 1960: The Geology of the Flat Point Area, Eastern Waira-rapa. N.Z. J. Ceo!. Ceophys. 3: 309-20.

    MURPHY, M. A.; SCHLANGER, S. O. 1962: Sedimentary Structures in I1has and Sao Sebastiao Formations (Cretaceous), Reconcavo Basin, Brazil. Bull. Amer. Assoc. Petro!' Ceo!. 46: 457-77.

    STONELEY, R. 1962: Marl Diapirism near Gisborne, New Zealand. N.Z. J. Ceol. Ceophys. 5: 630-4l.

    WATERHOUSE, J. B.; BRADLEY, J. 1957: Redeposition and Slumping in the Cretaceo-Tertiary Strata of S.E. Wellington. Trans. Roy. Soc. N.Z. 84: 519-48, pis. 33-7. .

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