New paleomagnetic pole and magnetostratigraphyof the Cauvery Basin sediments, southern India

M VENKATESHWARLU*

CSIR-National Geophysical Research Institute, Hyderabad 500 007, India.e-mail: mamila˙v@rediAmail.com

MS received 18 November 2019; revised 24 June 2020; accepted 11 July 2020

Magnetostratigraphy or magnetic polarity stratigraphy (MPS) is constructed with paleomagneticparameters for the Campanian–Maastrichtian (Upper Cretaceous) onshore sediment sequences of theCauvery Basin, southern India. Twenty-nine sedimentary outcrops in the vicinity of Ariyalur district ofTamil Nadu, India were studied using AF (5–150 mT) and thermal demagnetization (100–700�C). Theobserved remanence carrier is attributed to hematite through rock magnetic experiments. The virtualgeomagnetic pole (VGP) latitudes were computed using the acquired characteristic remanent magneti-zation (ChRM) directions. The mean ChRM produce Dm= 338, Im= –38, (a95=23.91�, k = 15.73,N=60). The mean VGP is estimated at 51.33�N, 292.71�E deriving a paleolatitude of 21.3�S. The con-structed magnetic polarity stratigraphy (MPS) is correlated with the standard geomagnetic polarity timescale (GPTS). The composite MPS of these sequences comprises of 12 magnetozones (6 normal and6 reversed events) that are corroborated with Chron C33n to Chron C30n of the GPTS. The derivedpaleolatitude position from the present study places Indian subcontinent at little shallow southernlatitudes indicating moderately higher drift velocities during Upper Cretaceous.

Keywords. Paleomagnetism; magnetostratigraphy; Upper Cretaceous; Cauvery Basin; southern India.

1. Introduction

The Cauvery Basin, southern India is a pericra-tonic basin located along the southeast coast ofIndia formed as a consequence of the break-up ofthe Gondwana land during the late Jurassic(Rangaraju et al. 1993). After the break up ofGondwana, the Indian subcontinent remainedisolated as an island continent and re-establishedbased on biotic links with Africa, Madagascar,South America, and Asia during the Upper Cre-taceous (Sahni and Bajpai 1988; Chatterjee andScotese 1999; Khosla and Sahni 2003). ConBgura-tion of the Indian plate changed during the UpperJurassic and lower Cretaceous as it separatedsequentially from Gondwana, east Gondwana,

Madagascar, and Seychelles Island (Chatterjee andScotese 1999). The plate reconstructions suggestthat India was an isolated island continent duringthe Cretaceous for more than 100 Ma until itdocked with Eurasia in early Eocene (Barron andHarrison 1980; Smith 1988). In a recent hypothesis,Chatterjee and Scotese (2010) suggested that theOman–Kohistan–Dras Island arc are the northernbiotic link between Africa and India during theUpper Cretaceous period. During the Cenomanianperiod, India rifted away from Madagascar andheaded northward at a speed of 18–20 cm/yearcovering a distance of about 6,000 km, and thenslowed to 5 cm/year during early Eocene after acontinental collision with Asia (Patriat andAchache 1984). The opening of the eastern Indian

J. Earth Syst. Sci. (2020) 129:222 � Indian Academy of Scienceshttps://doi.org/10.1007/s12040-020-01476-z (0123456789().,-volV)(0123456789().,-volV)

Ocean (Powell et al. 1988) is relatively complicated(CoDn 1992a, b) as India drifted away fromAntarctica and Australia. It is clear that Kerguelenplateau remained as one of the distinct paleogeo-graphic features in the Indian Ocean during thistime. This massive plateau may have remainedattached to the Indian subcontinent (by way of SriLanka) until 80 Ma (Hay and De Conto 1999).Among the Gondwana assembly, the Indian

continent moved at a rapid speed (PoornachandraRao and Bhalla 1981) and collided with the Eur-asian plate in early Palaeogene resulting in the riseof Himalayan mountain chain. The rapid move-ment of the Indian plate was recorded in marinemagnetic anomalies, the Rajmahal–Sylhet Trapsand the Deccan Traps in the form of magneticsignatures (Talwani et al. 2016). The Rajmahaltraps dated to be 117 ± 1 Ma (McDougall andMcElhinny 1970; Baksi 1990) resulted in a paleo-latitude position of 43�S and the Deccan Trapsdated to be 65.5 ± 2.5 Ma (Baksi 1987) resulted ina paleolatitude position of 30�S for the Indiansubcontinent. Thus, there occurred a drift ofabout 13o from Rajmahal Traps to Deccan Trapsperiod, for which there is no direct evidence ofPaleomagnetic data from the continental rocks.Achache et al. (1983) reviewed the relevant pale-omagnetic data for the late Mesozoic and Cenozoicof southeastern Asia and compared them with thepredictions of the model and put constraints onfuture tectonic models of the area. Paleomagneticdata are very scarce in southeastern Asia, since nopaleomagnetic data available on Indian part andalso the gap exists in the research data related tothe drift history of the Indian plate during theUpper Cretaceous. This gap is studied withpaleomagnetic signatures of Campanian–Maas-trichtian on-shore sediments of Cauvery Basin insouthern India in order to address the drift historyof the Indian plate and also to construct themagnetostratigraphy column during the UpperCretaceous.

2. Geology and sampling

The Cauvery Basin has undergone at least twomajor tectonic phases during its evolution. Theearly sheared rift extensional faulting initiatedduring Lower Jurassic/Lower Cretaceous (ShyamChand and Subrahmanyam 2001; Scotese 1997)and was followed by a progressive rift that seemsto have continued until the end of Turonian

(Watkinson et al. 2007). The syn-rift megasequence spans the Barremian to late Turonianpart of the sedimentary basin Bll and corre-sponds to the Gondwana, Dalmiapuram, andKarai formations. The post-rift mega sequence isa relatively attenuated succession. This includesthe Trichinopoly and Ariyalur Groups in whichthere is a major hiatus in the sedimentaryrecord. The post-rift sequence is characterized byits punctuated regressive nature of deposition.The post-rift mega sequence is composed ofshallow marine and Cuvial sandstones and sand-rich carbonates.

2.1 Ariyalur Group

The Ariyalur Group covers approximately 200 km2

area with a disconformable, overlain by theTrichinopoly Group. The general trend of thesesedimentary sequences is northeast–southwestinvariable, dipping regionally at 4–8� towards eastand divisible into four formations on the basis oflithological character, viz., Sillakkudi, Kal-lankurichchi, Ottakovil and Kallamedu, in theascending stratigraphic order (Sundaram and Rao1986). Figure 1 shows the sampling location mapdisplays Lower Cretaceous (late Aptian) to UpperCretaceous (late Maastrichtian) successions of theoutcrop sediments in Cauvery Basin. At the base,the Sillakkudi Formation is dominated by sand-stones that are well exposed along the Mettol andNochikulam areas. Sedimentological studies indi-cate that the sandstones are mineralogically andtexturally immature and poorly sorted. Abundanceof feldspar, especially acid plagioclase, indicatesrapid deposition from a nearby granite/gneissprovenance. Figure 2 shows the Beld photograph ofoutcrops of Ariyalur sections. The Sillakkudi For-mation (Bgure 2a, b) is characterized by clasticsediments with carbonate fractions and having athickness of 600 m. The sediments consist of oA-white to buA coloured, coarse-grained, texturallyimmature, poorly sorted, friable to hard sandstonewith occasional calcareous cement. The presence ofglauconitic pellets in the sandstones suggestsdeposition during a transgressive episode in apaleo-water depth of 30–60 m (Nagendra et al.2001). The Sillakkudi sandstone underlies theKallar Conglomerate Member, which is exposed instream sections near Kallar. Orange to yellowpebbles with abundant sub-angular to angular,pink to white pebbles and cobbles characterize the

222 Page 2 of 11 J. Earth Syst. Sci. (2020) 129:222

conglomerate bed, which is non-calcareous andindicative of sub-aerial deposition marks a hiatusduring the late Campanian. The Kallar Conglom-erate is considered as the upper member of theSillakkudi Formation and permits for easy regionalcorrelation (lithostratigraphic marker). The Kal-lankurichchi Formation (Bgure 2c, d) and its threemembers are marked by marine carbonates with athickness of 44 m and conformably overlie the Sil-lakkudi Formation. It starts with the FerruginousLimestone (FL) Member and above this is theLower Arenaceous Limestone (LAL) Membermarked by yellowish, massive, and compact lime-stone rich in silica. Overlying the LAL is theGryphaea Limestone (GL) Member identiBed byits reddish-brown colour and Bne-to-mediumgrained carbonate. At the top is the Upper

Arenaceous Limestone (UAL) Member markedby high terrigenous inCux. Sillakkudi and Kal-lankurichchi formations have equivalents in theadjoining Krishna–Godavari Basin (Raju andReddy 2016). The Ottakovil Formation (Bgure 2e,f) contains mollusks, bryozoans and rare burrowswith 600 m thickness. The lower contact withthe Kallankurichchi Formation is conformable,whereas the upper contact with the overlyingKallamedu Formation (300 m after Sundaram et al.2001) is unconformable. The Kallamedu Formationcontains cross-bedded sandstones indicative ofCuvial channel deposits that mark the end of theCretaceous in the Ariyalur area (Nagendra et al.2002). Sillakkudi Formation is represented byCampanian age, Kallankurichchi Formation isrepresented by lower to middle Maastrichtian age

Figure 1. Sampling (red boxes) location map of Ariyalur area, Cauvery Basin, southern India.

J. Earth Syst. Sci. (2020) 129:222 Page 3 of 11 222

and the late Maastrichtian is represented byOttakovil and Kallamedu Sandstone, respectivelyin Ariyalur Group.A total of*200 specimens from60orientedblocks

of 13 sites were catalogued for the paleomagneticstudies fromthequaliBedCampanian–Maastrichtiansedimentary lithosections in Ariyalur area of CauveryBasin.

3. Methods

The natural remanent magnetisation (NRM) ofall the specimens was measured using SpinnerMagnetometer (Model JR-6, AGICO, CzechRepublic), magnetic susceptibility using Kappabridge (Model MFK1-FA, AGICO, Czech

Republic) system and AF demagnetization(Molspin; Magnetic Measurements, UK) andthermal demagnetization (MMTD-80; MagneticMeasurements, UK) were carried out for mag-netic cleaning. Isothermal remanent magneti-zation (IRM) was imparted on representativespecimens to identify the magnetic mineralsand their domain state using pulse magnetizer(MMPM-10; Magnetic Measurements, UK).Selected samples were subjected to progressiveAF demagnetization at incremental steps from 5 to150 mT followed by thermal demagnetization atthe intervals from 100� to 700�C. Results from eachsample were plotted to evaluate the demagnetiza-tion response. Principal component analysis(Kirschvink 1980) was used to estimate meandirections of the magnetic components.

Figure 2. Field photographs showing the outcrops from Sillakkudi (a, b); Kallankurichchi (c, d) and Ottakovil (e, f) of UpperCretaceous, Cauvery Basin.

222 Page 4 of 11 J. Earth Syst. Sci. (2020) 129:222

Figure 3. Representative orthogonal vector diagrams (a), stereo plots (b), and intensity decay curves (c) for the AFdemagnetization. The data points marked by closed circles fall on to the horizontal plane and open circles on to the vertical planein orthogonal projections.

J. Earth Syst. Sci. (2020) 129:222 Page 5 of 11 222

Figure 4. Representative orthogonal vector diagrams (a), stereo plots (b), and intensity decay curves (c) for the thermaldemagnetization. The data points marked by closed circles fall on to the horizontal plane and open circles on to the vertical planein orthogonal projections.

222 Page 6 of 11 J. Earth Syst. Sci. (2020) 129:222

4. Results and discussion

The NRM intensity of magnetization range from0.11 to 14.01 mA/m. The overall calculated sus-ceptibilities range from 1 to 39 SI units. In a pilotstudy, both step-wise alternating Beld (AF) andprogressive thermal demagnetizations were carriedout on representative samples. Figures 3 and 4represent orthogonal projections (Zijderveld 1967),stereo plots and intensity decay curves of the vec-tors during step-wise AF and thermal demagneti-zation, respectively. The linear curve passesthrough the origin in most of the specimens and thedirections remain stable even at higher thermaldemagnetization steps. The magnetic susceptibilitymeasurements were done through successive ther-mal steps to check the chemical variations in the

samples and the same is shown in Bgure 5. Sampleand site mean directions were calculated statisti-cally (Fisher 1953) isolating characteristic rema-nent magnetization (ChRM) directions. Figure 6shows the section-wise mean directions with overallmean direction along with Alpha 95. Table 1 givesthe paleomagnetic results of the Upper CretaceousAriyalur sections.Representative specimens were subjected to

IRM magnetization in steps from 15 to 3000 mT.Preliminary IRM studies on few samples werereported in Papanna et al. (2014). The IRM curves(Bgure 7) explains that the specimens were unsat-urated (Hs) up to maximum available Beld of 3000mT suggesting hematite is the most significantmagnetic carrier.

4.1 Magnetostratigraphy

The record of geomagnetic polarity is establishedfrom the Upper Jurassic (Oxfordian). Three dis-tinct episodes of reversal behaviour are identiBedduring this time interval (Lowrie 2011). The oldestepisode, comprising frequent reversals in the UpperJurassic and Lower Cretaceous, is referred to as theM-sequence (Lowrie 2011). The youngest episode,comprising the Upper Cretaceous and Cenozoic,consists of frequent reversals known as the C-se-quence (Lowrie 2011). The M and C-sequences areseparated by an interval of 38 Ma span called theCretaceous Normal Polarity Superchron (CNPS),in which correlated magnetic anomalies are absent;

Figure 5. Curves of susceptibility measurements during ther-mal demagnetization for Ariyalur sections, Cauvery Basin.

Figure 6. Section-wise mean directions with grand mean (redcircle) and a95 = circle of conBdence at 95% probability level(green circle) for Upper Cretaceous Formations, CauveryBasin, southern India.

J. Earth Syst. Sci. (2020) 129:222 Page 7 of 11 222

evidently the Earth’s magnetic Beld did not reversepolarity during this time (Lowrie 2011).The episodes of reversing behaviour are long

enough to make tentative interpretations of thereversal process. It is evident from the patterns ofreversals that they do not occur cyclically. Makingallowance for the time spent in transition betweenopposite polarity states, statistical analysis indi-cates that the reversals in the M and C-sequencesoccur randomly. There is no convincing evidence torefute identiBcation of the CNPS as an uninter-rupted period of constant normal polarity. Thereare competing interpretations of its origin (Lowrie2011). Whereas researchers consider that theCNPS represents a special behaviour of the geo-dynamics and it has exceptionally long feature in acontinuous reversal process (Lowrie 2011).Figure 8 represents the magnetic polarity

stratigraphy (MPS) of the Upper CretaceousAriyalur Group, Cauvery Basin. MPS is correlatedwith the standard geomagnetic polarity time scale(GPTS) of LaBrecque et al. (1977). The correlationof Cretaceous stage boundaries to polarity Chronsis deBned in the geomagnetic polarity and strati-graphic time scale (Gradstein et al. 1995).

4.1.1 Campanian section (SillakkudiFormation)

The Campanian section is represented by Sil-lakkudi Formation (Sathurbhagam Sandstone,Kilpavalur grainstone, Sillakkudi Sandstone andKallar Conglomerate). Eleven oriented block sam-ples were investigated from two outcrops ofSillakkudi Sandstone. The NRM intensities rangefrom 0.51 to 6.99 mA/m and susceptibility valuesrange from 6 to 39 SI units. Two magnetozoneswere observed in this section with a normal eventand other is a reversed event and correlated withGeomagnetic Polarity Time Scale (GPTS) ofLaBrecque et al. (1977) which corresponds toChron C33N (Bgure 8).

4.1.2 Lower-middle Maastrichtian section(Kallankurichchi Formation)

The lower-middle Maastrichtian section is repre-sented by Kallankurichchi Formation. A total of 24oriented block samples from 11 limestone outcropsshow NRM intensities ranging from 0.21 to 14.01mA/m and susceptibility values range from 1 to 24SI units. The detailed demagnetization studyrevealed two normal and one reversed polarities inthis section and correlated very well with theGPTS, which corresponds to Chron C32N(Bgure 8).

4.1.3 Late Maastrichtian section (Ottakoviland Kallamedu)

The late Maastrichtian section is represented bytwo formations, i.e., Ottakovil and Kallamedurespectively. A total of 18 oriented block samplesfrom these two formations show NRM intensities,range from 0.11 to 12.31 mA/m and susceptibilityvalues range from 1 to 28 SI units. The detailed

Table 1. Paleomagnetic results of the Upper Cretaceous sequences, Cauvery Basin, southern India.

Section Dm Im a95 k N/n kp Lp km

KM 344 –26 15.89 34.40 5/13 60.5 292.1 –13.7

O 345 –25 18.58 19.71 12/45 61.5 291.0 –13.1

K 341 –65 12.35 42.69 22/84 29.5 273.9 –47.0

S 323 –34 23.85 22.59 11/36 42.9 310.3 –18.6

Mean 338 –38 23.91 15.73 50/162 51.3 292.7 –21.3

Note. KM: Kallamedu; O: Ottakovil, K: Kallankurichchi, S: Sillakkudi, Dm: mean declination,Im: mean inclination, a95: circle of conBdence at 95% probability level, k: precision parameter,N: number of samples, n: number of specimens; kp: VGP latitude, Lp: VGP longitude, andkm: paleolatitude.

Figure 7. Isothermal remnant magnetization (IRM) curvesfor Upper Cretaceous Formations, Cauvery Basin, southernIndia.

222 Page 8 of 11 J. Earth Syst. Sci. (2020) 129:222

demagnetization study revealed three normal andthree reversed polarities in this section and corre-lated very well with the GPTS, which correspondsto Chron C31N and C30N (Bgure 8).Themagnetic polarity stratigraphyofCampanian

to Maastrichtian sequences of Ariyalur Group yiel-ded 12magnetozones consisting of six normal and sixreversed events that are correlated very well withGPTS of LaBrecque et al. (1977) (Bgure 8).

The Alpha 95 is higher in Sillakkudi and Otta-kovil due to the paucity of the samples since mostof the outcrops are placed in subsurface. The meandirections may be correlated to the Deccan meandirections with a difference of 10–15�. Figure 9shows the migration of the Indian subcontinent andthe position of the Indian subcontinent duringUpper Cretaceous period (Cauvery Basin). Theoverall mean directions from paleomagnetic results

Figure 8. Lithostratigraphy versus magnetic polarity stratigraphy (MPS) of the studied Ariyalur Upper Cretaceous sections,Cauvery Basin, southern India. MPS is correlated with GPTS of LaBrecque et al. (1977). S.St: sandstone; L.St: limestone; VGP:virtual geomagnetic pole; MPS: magnetic polarity stratigraphy; GPTS: geomagnetic polarity time scale. The listed numericalages are from Gradstein et al. (2004) and Ogg et al. (2008). Thickness after Sundaram et al. (2001).

Figure 9. Migration of the Indian subcontinent after the Gondwana break-up and position of the Cauvery Basin, India duringUpper Cretaceous (ModiBed after Klootwijk 1976).

J. Earth Syst. Sci. (2020) 129:222 Page 9 of 11 222

from Upper Cretaceous sections (table 1) inferredthat the Indian subcontinent, during Upper Cre-taceous, was placed little shallow southern lati-tudes to the Deccan Traps at 21.3�S (Bgure 9).

5. Conclusions

Paleomagnetism and magnetostratigraphy studyon the Upper Cretaceous Cauvery Basin sedimentsprovide the following information:

• The rock magnetic analysis shows hematite asthe main remanence carrier.

• The mean direction results in the declination at338� and inclination at –38� (a95= 23.91�) andthe pole position at 51�N, 293�E with a paleo-latitude of 21.3�S.

• The MPS of Ariyalur Group sequences of Cau-very Basin recorded 12 magnetozones (6 normaland 6 reversed events) and correlated withGPTS of LaBrecque et al. (1977) from ChronC33n to Chron C30n.

• The paleolatitude position highlights the highervelocities of the drift of the Indian subcontinentduring Upper Cretaceous period.

Collection of more samples from Sillakkudi,Ottakovil and Kallamedu may produce morereBned paleolatitude position of the Indian sub-continent during Upper Cretaceous from CauveryBasin.

Acknowledgements

The author thanks the Director CSIR-NGRI forthe permission to publish these results. Prof RNagendra is acknowledged for the support and DrG Papanna is thanked for the help in collectionof the samples. Thanks are due to two anony-mous reviewers for their critical and helpfulsuggestions through which the manuscript isimproved to greater extent and Saibal Gupta forthe editorial handling. The author thanksDepartment of Science and Technology (Govt. ofIndia) for the Bnancial assistance (SR/S4/ES-271/2007).

Author statement

MV designed the research, participated in samplecollection, did data processing and analysis, wroteand edited the manuscript.

References

Achache J, Courtillot V and Besse J 1983 Paleomagneticconstraints on the Late Cretaceous and Cenozoic tectonicsof southeastern Asia; Earth Planet. Sci. Lett. 63 123–136.

Baksi A K 1990 Timing and duration of Mesozoic–TertiaryCood-basalt volcanism; EoS 71 1835–1836.

Baksi A K 1987 Critical evaluation of the age of the DeccanTraps, India: Implications for Cood-basalt volcanism andfaunal extinctions; Geology 15 147–150.

Barron E J and Harrison C G A 1980 An analysis of past platemotions in South Atlantic and Indian oceans; In: Mecha-nisms of continental drift and plate tectonics (eds) P Daviesand S K Runcorn, Academic Press, London, UK.

Chatterjee S and Scotese C R 1999 The breakup Gondwanaand the evolution of the Indian plate; In: Gondwanaassembly: New issues and perspectives (eds) A Sahni andLoyal R S, Ind. Nat. Sci. Acad., New Delhi, India.

Chatterjee S and Scotese C R 2010 New aspects of mesozoicbiodiversity; Lecture Notes in Earth Sci. 132 105–126.

CoDn M F 1992a Emplacement and subsidence of IndianOcean Plateaus and submarine ridges; In: Synthesis ofresults from scientiBc drilling in the Indian Ocean (eds) R ADuncan, D K Rea, R B Kidd, U Vonrad and J K Weissel,American Geophysical Union, Geophysical MonographWashington D C, pp. 115–125.

CoDn M F 1992b Subsidence of the Kerguelen Plateau: TheAtlantis concept; In: Proceedings, Ocean Drilling Program,ScientiBc Results (eds) S W Wise Jr, R Schlich and A APalmer Julson, Ocean Drilling Program, College Station,Texas, pp. 945–949.

Fisher R A 1953 Dispersion on a sphere; Proc. Roy. Soc.London A217 295–305.

Gradstein F M, Ogg J G and Smith A G et al. 2004 A geologictime scale 2004; Cambridge University Press.

Gradstein F M, Agterberg F P, Ogg J G, Hardenbol J, VanVeen P, Thierry J and Huang Z A 1995 Triassic, Jurassicand Cretaceous time scale; SEPM Spec. Publ. 54 95–126.

Hay W W and De Conto R M 1999 Comparison of modern andlate Cretaceous meridional energy transport and oceanol-ogy; In: Evolution of the Cretaceous Ocean/Climate Sys-tem (eds) E Barrera and C C Johnson, Geol. Soc. Am. Spec.Paper 332 283–300.

Khosla and Sahni A J 2003 Biodiversity during the Deccanvolcanic eruptive episode; J. Asian Earth Sci. 21 895–908.

Kirschvink J L 1980 The least-squares line and plane and theanalysis of paleomagnetic data; Geophys. J. Roy. Astron.Soc. 62 699–719.

Klootwijk C T 1976 The drift of the Indian subcontinent: Aninterpretation of recent paleomagnetic data; GeologischeRundschau 65 885–909.

LaBrecque John L, Kent Dennis V and Cande Steven C 1977Revised magnetic polarity time scale for Late Cretaceousand Cenozoic time; Geology 5 330–335.

Lowrie Willian 2011 Paleomagnetism, principles; In: Ency-clopaedia of Solid Earth Geophysics (ed.) Harsh K Gupta,Springer, pp. 962–963.

McDougall I and McElhinny M W 1970 The Rajmahal Trapsof India, K–Ar ages and Paleomagnetism; Earth Planet. Sci.Lett. 9 371–378.

Nagendra R, Nagendran G, Narasimha K, Jai Prakash B Cand Nallapa Reddy A 2002 Sequence stratigraphy of

222 Page 10 of 11 J. Earth Syst. Sci. (2020) 129:222

Dalmiapuram Formation Kallakudy Quarry – II, southIndia; J. Geol. Soc. India 59 249–258.

Nagendra R, Nallapa Reddy A and Jaiprakash B C 2001Outcrop sequence stratigraphy of Kallankuruchchi Forma-tion of Velliperijnjiyam mine, and its correlation withTancem mine, Ariyalur Group, Tamil Nadu; J. Pet. Geol.10 23–36.

Ogg J G, Ogg G and Gradstein F M 2008 The concise geologictime scale; Natural History Museum of Oslo University,Norway, 177p.

Papanna G, Venkateshwarlu M, Periasamy V and Nagendra R2014 Anisotropy of magnetic susceptibility (AMS) studiesof Campanian–Maastrichtian sediments of Ariyalur Group,Cauvery Basin, Tamil Nadu, India: An appraisal toPaleocurrent directions; J. Earth Syst. Sci. 123 351–364.

Patriat P and Achache J 1984 India–Eurasia collisionchronology has implications for crustal shortening anddriving mechanism of plates; Nature 311 615–621.

Poornachandra Rao G V S and Bhalla M S 1981 Paleomag-netism of Dhar traps and drift of the subcontinent duringthe Deccan volcanism; Geophys. J. Roy. Astron. Soc. 65155–164.

Powell C, Roots Mc A, Veevers S R, Scotese J J andChristopher R 1988 Pre-breakup continental extension inEast Gondwanaland and the early opening of the easternIndian Ocean; Tectonophys. 155 261–283.

Rangaraju M K, Agarwal A and Prabhakar K N 1993Tectonostratigraphy, structural style, evolutionary modeland hydrocarbon prospects of the Cauvery–Palar basins ofIndia; Indian Petrol. Publishers, Dehradun 1 371–398.

Raju D S N and Reddy A N 2016 Why there is a substantialdichroneity in biostratigraphic dating of Cretaceous

sediments in the Krishna–Godavari Basin and CauveryBasin – a review; ONGC Bull. 51 119–134.

Sahni A and Bajpai S J 1988 Cretaceous–Tertiary boundaryevents: The fossils vertebrate, palaeomagnetic and radio-metric evidence from peninsular India; J. Geol. Soc. India32 382–396.

Scotese C R 1997 PALEOMAP Software, Paleomap Project,http.//Scotese.com.

Shyam Chand and Subrahmanyam C 2001 Subsidence andisostasy along a sheared margin – Cauvery Basin, EasternContinental Margin of India; Geophys. Res. Lett. 282273–2276.

Smith A B 1988 Late Paleozoic biogeography of East Asia andpalaeontological constraints on plate tectonic reconstruc-tion; Phil. Trans. Roy. Soc. London 326A 189–227.

Sundaram R and Rao P D 1986 Lithostratigraphy of Creta-ceous and Paleo rocks of Tiruchirapalli District, TamilNadu, south India; Rec. Geol. Surv. India 115 9–19.

SundaramR,HendersonRA,AyyasamiKand Stilwell JD 2001A lithostratigraphic revision and paleoenvironmental assess-ment of the Cretaceous System exposed in the onshoreCauvery Basin, southern India; Cret. Res. 22 743–762.

Talwani M, Maria Ana Desa, Ismaiel Mohammad and KrishnaK S 2016 The tectonic origin of the Bay of Bengal andBangladesh; J. Geophys. Res. Solid Earth 121 4836–4851.

Watkinson M P, Hart M B and Joshi A 2007 Cretaceoustectonostratigraphy and the development of the CauveryBasin, southeast India; Pet. Geosci. 13 181–191.

Zijderveld J D A 1967 Demagnetization of rocks: Analysis ofresults; In: Methods in rock magnetism and Palaeomag-netism (eds) D W Collinson, K M Creer and S K Runcorn,New York, Elsevier, pp. 254–286.

Corresponding editor: SAIBAL GUPTA

J. Earth Syst. Sci. (2020) 129:222 Page 11 of 11 222