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Authors
Affiliations
1 Atomic Minerals Division, Department of Atomic Energy Jaipur - 302 004, IN
2 Atomic Minerals Division, Department of Atomic Energy Vadodara - 390 001, IN
Source
Journal of Geological Society of India (Online archive from Vol 1 to Vol 78), Vol 50, No 3 (1997), Pagination: 307-313
Abstract
In the region covering some 400 km2 immediately to the north of Narmada lineament between Dharmrai, Dhar district, Madhya Pradesh, in the east and Nakhal and Panwad, Vadodara district, Gujarat, in the west, numerous E-W to ENE-WSW trending linear fault zones (c.l km to 5 km long X 20 m to over 100 m wide) occur within the Deccan basalts and infratrappean rocks. Brownish, brecciated, calcareous rocks, often with pockets and veins of calcite (carbonatites ?) are found within such fracture zones, and many of them show intrusive-like features. These faults apparently have developed sympathetic to the major Narmada rift to the south which provided structural avenues for the emplacement of carbonatites and associated basic alkaline rocks as found at Ambadongar. Panwad, Kawant and Saidiwasan, as part of the Deccan volcanic episode. Comparison of major and selected trace element data on these carbonatitic (?) rocks with Woolley and Kempe's average trace elements in carbonatite indicates that they are significantly impoverised in Zr, Nb, Y, La and U compared to the carbonatites and phonolites and phonolitic nephelinites of Panwad, Saidiwasan and Nakhal which are enriched in these elements. Carbonate-rich rocks of Bakhatgarh and Katarkheda in the east are rich in CaO and P2O3 compared to those of Panwad and Kawant. Based on available data it is suggested that the carbonatitic (?) types found in the east may represent an early phase of carbonatite (?) impoverished in Zr, Nb, Y, La, U and Th compared to the late residual (?) phase found in the Panwad-Saidiwasan-Nakal area which records significant radioactivity (upto 0.04% eUPR) and higher abundances of Zr (0.06%) and Nb (upto 0.1 %).
Keywords
Petrology, Geochemistry, Carbonatite, Lower Narmada Valley, Madhya Pradesh, Gujarat.
