Monsoon rainfall and contrasting source rocks influenced sediment composition of peninsular basins along the east coast of India (western Bay of Bengal)

Climatic and Tectonic Control on the Bengal Fan Sedimentation Since the Pliocene

“…Sampling locations are shown in Figure 1 and the sample locations are tabulated in Table S1. Inorganic and organic carbon was removed by treating the freeze-dried and homogenized river bed samples and sediment samples with 0.6 N HCl (Peketi et al, 2020), followed by combustion at 550°C for 4 h. The inorganic and organic carbon free homogenized sediment samples were used for the determination of elemental concentrations as well as Sr-Nd isotopic ratios. The sediment samples were subsequently digested using HNO 3 -HCl-HF acid mixture following standard procedure.…”

“…Sr‐Nd isotope ranges and mean values of source rocks (DcB: Deccan basalts; APGC: Archean Proterozoic Gneissic Complex; HHC: Higher Himalayan Crystalline Series; LH: Lower Himalayas) are used for mixing calculation. Average Sr and Nd concentrations and isotope ratios of the source rocks (Peketi et al., 2020) are: Deccan Basalts (224.34 μg/g, 21.08 μg/g, 0.707113, −3.24), Archean Proterozoic gneissic complexes (377.85 μg/g, 45.66 μg/g, 0.760536, −30.72), Higher Himalayan Crystalline Series (80 μg/g, 18 μg/g, 0.76, −15) and Lesser Himalayas (94 μg/g, 26 μg/g, 0.85, −24.4). The data cluster is zoomed out for clear visibility.…”

“…Strontium and Nd were pre‐concentrated from the digested samples following conventional cation exchange columns filled with AG 50W‐X8. Lanthanide specific resin (Eichrom) was used to separate Nd from other REE using 0.27 N HCL as an eluent (Peketi et al., 2020). Strontium and Nd isotope ratios were measured with in‐house MC‐ICPMS (Nu Plasma III).…”

“…The upper Cretaceous to present sedimentary stratigraphies of these basins are described based on oil well drillings and other studies (Dangwal et al., 2008; Sastri et al., 1973). Although the Krishna, Godavari, Mahanadi, and Cauvery river systems primarily contribute to the sediment loading in these basins (Mazumdar et al., 2015; Pattan et al., 2008; Peketi et al., 2020), their contribution decreases with increase in the water depth as the major part of the sediment load of these rivers is deposited within the deltas and dispersed within the shelf and continental rise of India (Einsele et al., 1996). Geophysical studies show that the deep‐water (2,500 m) sedimentation in the peninsular basins may be markedly influenced by the Bengal fan sediments (Dangwal et al., 2008) primarily fed by the Ganga‐Brahmaputra river system (Curray & Moore, 1971; Curray et al., 2003), which may be attributed to an order of magnitude greater sediment flux of Ganga‐Brahmaputra river system compared to that of peninsular rivers (Einsele et al., 1996).…”

Isolating Detrital and Diagenetic Signals in Magnetic Susceptibility Records From Methane‐Bearing Marine Sediments

“…This sediment discharge is dominated by smectite group clays with minor quartz, feldspar, and kaolinite (Subramanian, 1980). Weathering and sediment transport within the Krishna-Godavari Basin is strongly influenced by monsoon rainfall (Giosan et al, 2017;Kale, 2007;Peketi et al, 2020). The South Asian monsoon has a fundamental impact on continental margin sediment accumulation in Bay of Bengal (e.g., Clemens et al, 2021;Colin et al, 1998;Weber et al, 2018).…”