The Proterozoic Chotanagpur Granite Gneiss Complex (CGGC) at the northern boundary of the Central Indian Tectonic Zone (CITZ) of the eastern Indian shield preserves relics of fossilized oceanic back-arc crust. We describe the field, petrographical and geochemical characteristics of the mafic rocks comprising pillow basalts and dolerites from the Bathani area of the northern fringe of the CGGC, eastern India. The basalts consist of plagioclase feldspar, hornblende, opaque minerals (Fe–Ti oxide) and chlorite, and the dolerite consists of plagioclase, hornblende and opaque minerals. Our data indicate that the Bathani mafic rocks have tholeiitic to transitional composition and are overprinted by greenschist facies metamorphic conditions; however, REE and fluid immobile elements preserve their primary geochemical signatures. The (La/Sm)N ratios (1.38–2.15) and chondrite-normalized REE patterns point to an enriched mid-ocean ridge basalt (E-MORB) mantle source. Geochemical characteristics indicate a mixed signature of MORB and arc tholeiite with enrichment of Ba, Th, Eu and Sr, similar to that of back-arc supra-subduction zone ophiolites. These mafic rocks are the product of MORB-like magma derived from a depleted mantle corresponding to < 2% partial melting of spinel lherzolite, enriched by subduction-induced slab metasomatism and melting. The Bathani mafic rocks are representative of the upper part of a supra-subduction zone columnar ophiolite section, which was emplaced onto the present-day northern margin of the CGGC during suturing of the northern and southern Indian block at c. 1.9 Ga during the Nuna amalgamation.
The Kashmir Valley in northern India preserves a fossiliferous Plio-Pleistocene sedimentary record extending in time almost 5 myr. These fluvio-lacustrine sediments are commonly called the Karewas, and represent an ancient lake system with drainages derived from the Greater Himalayas and Pir Panjal Ranges. Although fossils have been known from this region for more than 150 years, the record is not as rich or taxonomically well resolved as the dense fossil record of the southern Siwalik Group. Here, we report the first specimen of a Quaternary gomphothere, cf. Sinomastodon sp. from the Kashmir Valley, along with new occurrences of Equus cf. sivalensis. This is the youngest gomphothere known from the Indian Subcontinent, representing a group of proboscideans hitherto thought to have gone locally extinct at the end of the Pliocene. Sinomastodon is commonly found in eastern and southeast Asia, and its presence in the Kashmir Valley suggests robust dispersal routes from southeast Asia to the high Himalayas. The presence of this browsing proboscidean in the Pleistocene suggests a unique refugial forested intermontane ecosystem, similar to those found in southern China, different from the savannah ecosystems found in the Siwalik Group south of the mountains.
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