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A. C. Banerjee ¹, Des Raj ¹, Manas Roychowdhury ²

Affiliations
1 Geological Survey of India, Sector 10A, Gandhinagar - 382 043, IN
2 Coal Wing, Geological Survey of India, 29, J. N. Road, Calcutta - 700 016, IN

Abstract

Some samples from a chrome spinel-bearing intrusive picrite within olivine rich Deccan basalts at Limbdi in Saurashtra show anomalous high contents of gold (148-231 ppb), platinum (15-125 ppb) and palladium (17-311 ppb). Other samples bear an avenge of ∼6 ppb of gold, ∼31 ppb of platinum and ∼42 ppb of palladium. Sulphide mineralisation in the picrite is of extremely fine grain size, with low to moderate whole-rock contents of sulphur varying between 0.08 to 0.53 %. Higher values of gold and platinum are found in the western olivine-rich portion of the intrusive, while at surface level platinum/palladium ratio decreases due east with increase in palladium. This intrusive with higher average contents of precious metals could be a potentid target for exploration. Such high contents of gold, platinum and palladium are hitherto unreported from Deccan volcanic province.

Keywords

Gold, Platinum, Palladium, Economic Geology, Picrite, Deccan Trap, Saurashtra, Gujarat.

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G. Mukhopadhyay ¹, S. K. Mukhopadhyay ¹, Manas Roychowdhury ¹, P. K. Parui ¹

Affiliations
1 Geological Survey of India, Coal Wing, DK-6, Sector-II, Salt Lake, Kolkata - 700 091, IN

Abstract

Gondwana Basins of India occur within the suture zones of Precambrian cratonic blocks of Peninsular India along some linear belts. More than 99% of the total coal resource of the country is present within these basins. The basins are demarcated by boundary faults having graben or half-graben geometry.

These basins preserve a thick sedimentary pile deposited over nearly 200 million years from latest Carboniferous to Lower Cretaceous. However, due to lack of well-constrained data, age of most of the formations is assigned tentatively. This has resulted in diversified views on both intra- and inter-basinal stratigraphic correlation particularly in case of Upper Gondwana formations.

It is well recognised that there are distinct spatial and temporal similarities in lithological, faunal and floral distribution in different Gondwana Basins of southern continents, including India, that were once part of supercontinent Gondwanaland. To address the problems of Indian Gondwana stratigraphy, during the present study, some unique events, also recognised in other parts of Gondwanaland, like marine flooding surfaces, large scale tectonic events or major change in depositional environment have been used as a tool for temporal correlation within the Gondwana Basins of India. Many of these events have been dated from different basins elsewhere. Considering these major events as time planes the total time span of deposition in Gondwana Basins has been classified into seven time slots. Recognition of these time planes helps in interbasinal correlation of different formations in Indian Gondwana basins and assigning the age, wherever available. This approach also helps in better understanding of basinal history. Unless otherwise mentioned, the time scale proposed by International Commission on Stratigraphy (2004) has been followed in this paper.

Keywords

Indian Gondwana Basins, Stratigraphy, Global Events, Depositional History.

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Manas Roychowdhury ¹, T. K. Saha ¹, Dipayan Guha ¹, R. L. Munshi ¹

Affiliations
1 Operations Gujarat, Geological Survey of India, Gandhinagar, IN

Abstract

Sauropod nest-sites having well-preserved tubocanaliculate types of eggs have been found within the Lameta Formation at Ihalod taluka, Panchmahals district, Gujarat. Four morphotypes of eggs have been distinguished based on thickness and microstructure of eggshell. Dinosaur eggs have been found in three horizons in the same stratigraphic section indicating a site fidelity which is for the first time being reported from the Lameta Formation of India.

Keywords

Palaeontology, Dinosaur Eggs, Panchmahals, Gujarat.

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