Tuesday, August 6, 2013

Some Interesting Papers On Himalayan Sedimentary Record By Indian Academics

A long time ago I mused that my perception was that in the context of Indian geology research, papers in top international sedimentary journals featured more Bengali geologists based in Universities in Bengal and eastern parts of India than from any other ethnic or linguistic region in India. That was fun lazy speculation on my part but perhaps not entirely wrong.

So, it is very refreshing to see a flurry of papers in recent issues of Sedimentary Geology from non Bengali research groups from other parts of the country as well!

1) Early Oligocene paleosols of the Dagshai Formation, India: A record of the oldest tropical weathering in the Himalayan foreland - Pankaj Srivastava, Subhra Patel, Nandita Singh, Toshienla Jamir, Nandan Kumar, Manini Aruche, Ramesh C. Patel

As the Indian collision with Asia progressed, the sea of Tethys shrank. Marine environments gave way to terrestrial basins. This work uses ancient soils that formed on these early terrestrial sediments during breaks in sedimentation to infer paleoclimate. The conclusion is that the climate was tropical with monsoonal conditions.

2)  Late Miocene–Early Pliocene reactivation of the Main Boundary Thrust: Evidence from the seismites in southeastern Kumaun Himalaya, India - Anurag Mishra, Deepak C. Srivastava, Jyoti Shah

The Himalayan terrain is broken up by several major thrust faults. Out of these, the Main Boundary Thrust brings into contact the Proterozoic Lesser Himalayas over the Cenozoic foreland basin sediments. The nature and reactivation history of the Main Boundary Thrust is not completely understood. A study of soft sediment deformation in foreland basin sediments in the vicinity of the Main Boundary Thrust documents sedimentation contemporaneous with seismic events.  Magnetostratigraphy indicate a Late Miocene-Early Pliocene reactivation of this major thrust fault.

3)  Exploring the temporal change in provenance encoded in the late Quaternary deposits of the Ganga Plain - Shailesh Agrawala, Prasanta Sanyal, Srinivasan Balakrishnan, Jitendra K. Dash

The rivers in the Ganges plains receive a lot of sediments from the Himalayas. But that is not their only source of sediment. Rivers like the Chambal, draining the Indian craton composed mainly of Precambrian granites and meta-sedimentary and meta-igneous rocks and the Late Cretaceous -Earliest Cenozoic Deccan Basalts contributes prodigious amounts of sediment especially to the Yamuna. A geochemical analysis of cored sediments from the Yamuna finds important contribution through the Pleistocene from both Himalayan and cratonic sources. Interestingly, there is a climatic control on the relative proportions of sediments received from the two sources. Himalayan sediments dominate during interglacial phases while cratonic sediments dominate during glacial phases. Expansion of mountain glaciers during cold intervals would have reduced supply of sediments from the Himalayas.

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