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

B. S. Kotlia ¹, M. S. Bhalla ², Nalin Shah ¹, G. Rajagopalan ³

Affiliations
1 Department of Geology, Kumaun University, Nainital-263 002, IN
2 National Geophysical Research Institute, Hyderabad-500 007, IN
3 Birbal Salmi Institute of Palaeobotany, Lucknow-226 007, IN

Abstract

Palaeomagnetic studies were carried out in the fluvio-Iacustrine sediments of Bhimtal and Bhowali basins (Kumaun Himalaya) and of Lamayuru basin (Ladakh Himalaya). The results were supplemented by radiocarbon dating. For the first time in the terrestrial sediments of the Quaternary-Holocene age in the Indian subcontinent, three minor reversal polarity events have been recorded at Lamayuru (ca. 35.5 ± 0.6 ka BP), Bhimtal (29.8-25.6 ka BP), and Bhowali (ca. 7.7 ± 0.13 ka BP). Since the upper most portion of the Lamayuru section indicated a reversal event, it may be significant to correlate it with the Indian Ocean event estimated as 40 ka BP. It is suggested that the Bhimtal event may be correlated with the widely known Mono Lake excursion which is fixed at 28-26 ka BP. Among the Holocene events, only a few are known, e.g., an event in the Solberga sediments (Sweden) estimated at ca. 10 ka BP; an event from Central Asia, dated at about 9 ka BP; the Erieau excursion, upper part of which has been estimated at about 7.6 ka BP; and the youngest event known as the Starno event (2.8 ka BP). The initial reports of the palaeomagnetic events, described in this paper, may be highly significant for examining several more sections as the events should he found repeatedly in sediments of same age in a given sedimentary environment.

Keywords

Magnetostratigraphy, Quaternary-Holocene, Reversal events, Fluvio-Iacustrine Deposits, Kumaun, Ladakh Himalaya.

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Abhaya P. Srivastava ¹, G. Rajagopalan ¹

Affiliations
1 Birbal Sahni Institute of Palaeobotany, 53, University Road, Lucknow 226007, IN

Abstract

No Abstract.

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C. P. Rajendran ¹, G. Rajagopalan ², Narayanaswamy ¹

Affiliations
1 Centre for Earth Science Studies, Trivandrurn 695031, IN
2 Birbal Sahni Institute of Palaeobotany, Lucknow 226007, IN

Abstract

An event of transgression (8000-6000 Y.B.P.) and another event of regression (30Q0..5000 Y.B.P.) which gave rise to extensive peat and shell deposits during Holocene in Kcrala is recorded. The initiation of the backwater system in Kerala is linked to these events.

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Savita Ghate ¹, Hema Raghavan ¹, G. Rajagopalan ²

Affiliations
1 Deccan College, Pune, IN
2 Birbal Sahani Institute of Palaeobotany, Lucknow, IN

Abstract

¹⁴C dates supplemented by micromorphological studies of Karal rocks are presented. ¹⁴C dates, micromorphological analysis and sedimentological processes reveal that the calcite cementation of Karal rock, drift-wood and lithounits have taken place in several phases and not in a single stage. This appears to be the main reason for the discrepancy of ¹⁴C dates of the Kara1 and wood samples occurring at the same stratigraphic position and depth.

Keywords

Karal Rocks, Age, Quaternary Geology, Maharashtra.

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N. H. Hashimi ¹, R. Nigam ¹, R. R. Nair ¹, G. Rajagopalan ²

Affiliations
1 National Institute of Oceanography, Dona Paula, Goa-403 004, IN
2 Birbal Sahni Institute of Palaeobotany, Lucknow-226 007, IN

Abstract

A new Holocene curve is generated for the western Indian continental margin. While constructing this curve careful selection of the dates were made by giving due considerations to the genetic characteristics of the dated material. This new curve shows a low at 100 m depth around 14,500 years BP and a rise to 80.m depth around 12,000 years BP showing a rate of ˜10m/1000 years which was followed by astillstand for about 2,000 years. From 10,000 to 7,000 years it rose at a very high rate (˜20 m/1000 years). Beyond 7,000 years BP it showed minor fluctuations.

Keywords

Holocene, Sea Level Fluctuation, Sea Level Curve, Arabian Sea, West Coast of India.

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G. Rajagopalan ¹

Affiliations
1 Lucknow, IN

Abstract

No Abstract.

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R. Sinha ¹, V. N. Sastry ², G. Rajagopalan ³

Affiliations
1 Engineering Geology Group, Indian Institute of Technology, Kanpur - 208 016, IN
2 Bhabha Atomic Research Centre, Bombay, Mumbai, IN
3 Birbal Sahni Institute of Paleobotany, 53 University Road, Lucknow, IN

Abstract

Data on geochemical analysis of sediment cores obtained from Lake Priyadarshini, Schirmacher Range, Eastern Antarctica is presented. Elemental distribution in vertical profiles has been correlated with the redox cycles which provide information about depositional environment. Very low sedimentation rate is inferred in the periglacial environment of Antarctica with a very limited sediment supply. A ¹⁴C age of ∼8 kyr indicates that the lake formed in early Holocene as a result of major deglaciation after the end of the last glacial period.

Keywords

Lacustrine Sedimentation, Geochemistry, Holocene, Radioisotopes, Antarctica.

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