Rp. Kumar et al., Down core variation of texture and clay mineralogy in a sediment core (SK-72/1) from Bengal Deep Sea Fan: Implication to climate and provenance, I J MAR SCI, 28(1), 1999, pp. 24-28
Texturally, the samples are silty-clay to clayey-silt. The clay mineral ass
emblage is predominated by chlorite, followed by montmorillonite, illite an
d kaolinite. Non-clay minerals are quartz and calcite. Semi-quantitative cl
ay species abundances on diffractograms and crystallinity indices (CI) of i
llite and montmorillonite were also estimated. CI of montmorillonite reflec
ts the poorly crystalline nature. It is inferred that the clays are of detr
ital origin most likely from the soils of Himalayan region drained by river
s Ganges and Brahamaputra and that a portion of montmorillonite could be po
ssibly sourced in the soils derived from the weathering of flood basalts at
the Deccan Plateaue of west central India and transported by the east flow
ing rivers of the peninsula However, the clay sized quartz is of detrital o
rigin, whereas calcite is mostly biogenic. Down core variation of clay mine
ral assemblage at a depth of 40 cm indicates a shift of climate from cold/d
ry to warm/humid condition during 12 x 10(3) y BP.