Sup(10)Be variation in surficial sediments of the Central Indian Basin

Abstract

Distribution of 10Be in systematically collected (degree + degree interval at 10 to 16 degrees S; 73.5 to 76.5 degrees E) surficial siliceous ooze, siliceous clay and pelagic clay sediments (top 2 cm) from the abyssal Central Indian Basin and the Andaman Sea is used to evaluate sources and to decipher the transport pathways of sediment particles, demarcate sediment depocenters and erosional areas. While sup(10)Be concentrations display a wide variation (0.12-5.56 x 10 sup(9) atoms g sup(-1)) with an average of 3.58 x 10 sup(9) atoms g sup(-1) in the Central Indian Basin, the values in the Andaman Sea are uniform with an average of 1.49 x 10 sup(9) atoms g sup(-1). The sup(10)Be/sup(9)Be values in the Central Indian Basin sediments range between 0.06 and 2.99 x 10 sup(-8) atoms atoms sup(-1) and average to approx. 1.56 x 10 sup(-8) atoms atoms sup(-1). Correlation of sup(10)Be data with some selected major (Al, Mn, Ti) and trace (Rb and Ba) elements suggest that large part of the isotope has been supplied through direct atmospheric fallout from the water column and minor part from lithogenic detrital flux. Significantly lower sup(10)Be accumulation rates in the Central Indian Basin and an order of magnitude higher in the Andaman Sea sediments compared to the estimated global average production rates indicate removal of the isotopes at the continental margins. Bottom topography seems to exert control on local Sup(10)Be variation, where sediments deposited in valleys or topographic depressions contain higher sup(10)Be concentrations in contrast to the probably erosion-dominated areas at the slopes and troughs.