Glacial/interglacial changes in sediment rain rate in the SW Indian Sector of subantarctic Waters as recorded by230Th,231Pa, U, and δ15N

摘要: High-resolution records of opal, carbonate, and terrigenous fluxes have been obtained from a high-sedimentation rate core (MD84-527: 43°50′S; 51°19;′E; 3269 m) by normalization to 230Th. This method estimates paleofluxes the seafloor on point-by-point basis distinguishes changes in sediment accumulation due variations vertical rain rates those syndepositional redistribution bottom currents. We also measured δ15N evaluate nitrate utilization overlying surface waters associated with paleoflux variations. Our results show that opal during Holocene stage 3, based 14C dating, were respectively tenfold fivefold higher than rates, At this particular location, appear be mainly controlled currents rather water column. Correction for improved time resolution can achieved 230Th disclose important rates. found relatively high but variable two maxima centered at 36 30 kyr B.P., low 2 deglaciation pronounced maximum early Holocene, interpret record as reflecting production climate-induced latitudinal migration southern ocean frontal system. Sediments deposited periods authigenic U concentrations, suggesting more reducing conditions sediment, Pa-231/Th-230 ratios, increased scavenging Sediment is circa 1.5 per mil isotopic deglaciation. The recorded period depletion. suggests do not simply reflect system structure upper Increased stratification could produced meltwater lid, leading lower supply waters.