Journal of Geological Society of India (Online archive from Vol 1 to Vol 78)

M. N. Malur ¹, R. Nagendra ¹

Affiliations
1 Department of Geology, University of Mysore, Manasagangotri, Mysore 570006, IN

Abstract

Microstylolites occurring in Carbonate rocks of Bhima Group (late Precambrian), Karnataka, South India, have been classified on their geometrical aspects, Their origin is attributed to a possible local disturbance during the early diagenetic period.

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R. Nagarajan ¹, J. S. Armstrong-Altrin ², R. Nagendra ³, J. Madhavaraju ⁴, J. Moutte ⁵

Affiliations
1 School of Civil Engineering, Sastra University, Thanjavur - 61 3 402,, IN
2 Centro de Investigaciones en Ciencias de la Tierra, Universdad Autonoma del Estado de Hidalgo, Crudad Universitaria, Carretera Pachuca-Tulancingo km 4 5, Pachuca, Hidalgo 42 1 84, MX
3 Department of Geology, Anna University, Chennai - 600 025, IN
4 Institute do Geologia, Estacion Regional del Noroeste, Universidad Nacional Autonoma de Mexico, Apart Postal 1039, Hermosillo, Sonora 83000, MX
5 Centre SpiNC, Ecole des Mines, 158 cours Fauriel, F 42023, Sant-Etienne, FR

Abstract

Petrographic, major, trace, and rare earth element compositions of quartz arenites, arkoses, and siltstones of Neoproterozoic Rabanpalli Forrnation of Bhima Basin have been investigated to understand the provenance. The quartz arenites, arkoses, and siltstones have large variations in major element concentrations. For example, quartz arenites and arkoses contain the hlgher Si0₂ (average with one standard deviation being 97±1,73±2,respectively) and lower Al₂O₃ (0 95±0 4, 9 6±O 9, respectlvely) concentrations than siltstones (SiO₂=64±4, A1₂0₃=14±1), which is mainly due to the presence of quartz and absence of other Al-bearing minerals in relation with rock types. This is also supported by our petrography, since quartz arenites and arkoses contain significant amount of quartz relative to feldspar and lithic fragments. The observed low CIA values and A-CN-K diagram suggest that the sedimentary rocks of Rabanpalli Formation have undergone K-metasomatism.

The Co, Ni, Cr, Ba, Zr, Hf, and Th values are higher in siltstones than quartz arenites and arkoses. The EU/EU^*, (La/LU)_en, La/Sc, Th/Sc, Th/Co, Th/Cr, Cr/Th ratios, and Cr, Ni, V, and Sc values strongly suggest that these sediments were mainly derived from the felsic source rocks. This interpretation is also supported by the Th/Sc versus Sc bivariate and La-Th-Sc triangular plots. The rare earth element (REE) patterns of these rocks also support their derivation from felsic source rocks. Further more, these rocks exhibit higher LREE/HREE ratio (8±4) and a significant negative Eu anomaly (0 77±0 16), which indicate the felsic igneous rocks as a possible source rocks.

Keywords

Geochemistry, Paleoweathering, Provenance, K-Metasomatism, Sandstone, Bhima Basin, Karnataka.

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R. Nagendra ¹, R. Kannan ¹, R. Bhavani ¹, P. Shanmuga Johari ², A. Nallapa Reddy ³, B. C. Jaiprakash ⁴

Affiliations
1 Center for Geoscience and Engineering, Anna University, Chennai - 600 025, IN
2 Department of Earth Sciences, University of Windsor, Windsor, Ontario, CA
3 Regional Geology Laboratory, Oil and Natural Gas Corporation Ltd , Chennai - 600 034, IN
4 Forward basin, ONGC, Tnpura Project, Badarghat Complex, Agarthala - 799 014, IN

Abstract

Twenty-four Pleistocene-Holocene deepwater benthic foramimferal species were identified based upon taxonomic criteria from a 26 m core sample collected during Academik Aleksandr Sidorenko cruise. The quantitative data of benthic foraminifera) taxa is treated statistically using multi vanate (both factor and cluster) techniques to understand the relationship between species assemblages and environmental parameters. The temporal distribution of samples in cluster II closely coincides with the distribution of higher loading values of factor 1 Similar associations were identified for cluster III with factor 2 and cluster IV with factor 3. However the faunal relative abundances along with %. Total Organic Content (TOC) values broadly divides the core into two environmentally significant zones viz, Zone 1 (between 1322 6m and 1321 6 m) which is characterised by high abundance of Cassiduhna cannata followed by Pullenia bulloides and Hoeglundina elegans having positive relationship with low TOC values ranging from 0 12 to 1 14 and Zone 2 (between 1321 6m and 1320 1 m), which is characterised by high percentages of TOC values ranging from 1 32 to 2 52, whereas Buhmina aculeata shows maximum abundance followed by Bohvina robusta, Cibiadoides kullenbergi and Osangulana culter, suggesting that these species prefer high nutrient environment.

Keywords

Benthic Foraminifera, Pleistocene, Holocene, Tuticonn, Bay of Bengal.

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R. Nagendra ¹, R. Raja ¹, A. Nallapa Reddy ², B. C. JaiPrakash ³, R. Bhavani ¹

Affiliations
1 Centre for Geoscience and Engineering, Anna University, Chennai - 600 025, IN
2 Regional Geology Laboratory, Oil & Natural Gas Corporation Ltd., Chennai - 600 034, IN
3 Geology Division, ONGC, Tripura Project, Badarghat complex, Agartala - 799 014, IN

Abstract

No Abstract.

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R. Nagendra ¹, G. Nagendran ¹, K. Narasimha ², B. C. JaiPrakash ³, A. Nallapa Reddy ²

Affiliations
1 Centre for Geosciencc and Engineering, Anna University, Chennai - 600 025, IN
2 Regional Geology Laboratory, Oil & Natural Gas Corporation Ltd., Chennai - 600 034, IN
3 Geology Division, ONGC, Tripura project, Badarghat complex, Agartala - 799 014, IN

Abstract

A sequence stratigraphic framework is worked out for the first time for the Dalmiapuram Formation exposed in Kallakudi quarry near Kallakudi village in Tiruchirapalli District. Thc complete lithological succession of this formation is designated as 'Dalmiapuram Sequence' of latest Albian - Cenomanian age and consists of grey shale, coral/algal limestone and bedded biostromal limestone and marl in ascending order. Grey shale rests unconformably ovcr thc Archaean basement. This contact forms the lower sequencc boundary of Dalmiapuram Sequence. The middle lithounit, the coral algal limestone rests ovcr grey shale. This unit abruptly grades into bedded limestone/marl alternations. This abrupt termination of coral algal limestone may be due to relative sea level rise and possibly this surface represents 'drowning unconformity'. The upper lithounit, which has alternating bands of biostromal limcstonc and marl, might indicatc cyclic carbonate precipitation (?Milankovich cycles). This unit is unconformably overlain by Neogene Cuddalore sandstone. This unconformity surface represents the upper boundary of the sequencc. The entire Dalmiapuram Sequence appears to have been deposited as Transgressive Systems Tract (TST) dcposit and got exposed as a result of basinal rise.

Keywords

Sequence Stratigraphy, Dalmiapuram Sequence, Albian-Cenomanian, Kallakudi, Tamil Nadu.

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D. Bakkiaraj ¹, R. Nagendra ¹, R. Nagarajan ², John S. Armstrong-Altrin ³

Affiliations
1 Department of Geology, Anna University, Chennai - 600 025, IN
2 Department of Applied Geology, School of Engineering and Science, Curtin University, CDT 250, 98009, Miri, Sarawak, MY
3 Unidad Academica de Geologia Marina y Ambiental, Instituto de Ciencias del Mar y Limnologia, Universidad Nacional Autonoma de Mexico, Mexico D.F., C.P. 04510, MX

Abstract

Major, trace and rare earth elements (REE) composition of sandstones from the Upper Cretaceous Sillakkudi Formation, Ariyalur Group, Cauvery Basin were studied to decipher their weathering and provenance history. Texturally, these sandstones are immature, poorly sorted and grain supported. Abundance of feldspars especially, plagioclase indicates rapid deposition of sediments from a nearby source rocks. Using the geochemical classification diagram the Sillakkudi sandstones are classified as fe-sand, quartz arenite, litharenite, sub-litharenite, sub-arkose, arkose, and wacke types, which is also supported by the petrography study. The transition trace elements like Co, Ni, and V are higher in the Sillakkudi sandstones than upper continental crust (UCC) values. However, the Sillakkudi sandstones are lower in Cr (mean ∼21) content than average UCC value (∼35). The poor correlation between Cr and Ni (r = 0.08, number of samples n = 20) imply that these sandstones were derived from felsic source rocks. Similarly, the Eu/Eu* (0.35-1.73), La/Sc (1.93-9.36), Th/Sc (0.41-6.57), Th/Co (0.14-5.01), Th/Cr (0.23-2.94), and Cr/Th (0.34-4.28) ratios support a felsic source for the Sillakkudi sandstones. The significant enrichment of Zr, Hf, and Th in fe-sand, sub-arkose and litharenite could be related to the presence of heavy minerals, especially zircon. However, the zircon geochemistry did not affect the REE distribution and its patterns in the Sillakkudi sandstones. The Chondrite normalized REE patterns of Sillakkudi sandstones are characterized by relatively flat HREE (Gd/Yb_CN = ∼0.73-2.41; subscript _CN refers to chondrite normalized value), enriched LREE (La/Sm_CN = ∼3.39-5.82) and negative Eu anomaly (mean value Eu/Eu* = 0.80). The Gd/Yb_CN ratios (∼0.73-2.50) are less than 2.5, which suggest that these Sillakkudi sandstones were derived from the less HREE depleted source rocks. The comparison of REE patterns and its Eu anomalies to the source rocks reveals that the Sillakkudi sandstones received a major contribution of sediments from Dharwar craton.

Keywords

Geochemistry, Zircon, Sandstones, Upper Cretaceous, Sillakkudi, Cauvery Basin.

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R. Nagendra ¹, Satish J. Patel ², Rakesh Deepankar ¹, A. N. Reddy ³

Affiliations
1 Department of Geology, Anna University, Chennai - 600 025, IN
2 Department of Geology, M.S. University, Vadodara - 390 002, IN
3 Oil and Natural Corporation Ltd, Chennai - 600 049, IN

Abstract

Well preserved ichnofossils were found in Kulakkalnattam sandstone exposed at Kulakkalnattam stream in Ariyalur area, Cauvery Basin. It consists of infaunal structures of both suspension and deposit feeders. Five ichnofossils are present in a fine to coarse grain sandstone which includes Ophiomorpha, Palaeophycus, Planolites Skolithos, and Thalassinoides. The study infers that ichnofossils Skolithos and Ophiomorpha are infaunal colonization of the suspension feeders in high energy condition in shifting substrate, whereas Thalassinoides and Planolites-Palaeophycus ichnofossils indicate infaunal deposit feeders living at the sediment-sediment interface in low to moderate energy conditions. Furthermore, the abundance and diversity of the trace fossils indicates there was alternatively fluctuations in energy conditions which lead to development of Skolithos and Cruziana ichnofacies type condition during the deposition of Kulkkallanattam sandstone in foreshore-shoreface environments.

Keywords

Ichnofossils, Kulakkalnattam Sandstone, Ariyalur Area, Cauvery Basin.

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P. K. Kathal ¹, R. Nagendra ², R. Raja ², A. Nallapa Reddy ³, B. C. Jayaprakash ⁴, R. Bhavani ²

Affiliations
1 Centre of Advanced Study in Geology, Dr. H.S.G. University, Sagar - 470 003, IN
2 Centre for Geoscience and Engineering, Anna University, Chennai - 600 025, IN
3 Regional Geology Laboratory, Oil and Natural Gas Corporation Ltd., Chennai - 600 034, IN
4 Geology Divsion, ONGC, Tripura Project, Badarghat Complex, Agartala - 799 014, IN

Abstract

No Abstract.

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