Abstract
This study utilizes the (super 230) Th normalization method to estimate particle fluxes and focusing factors in two cores from the Flores and Timor Seas. In the Flores Sea both the mass accumulation rates (MARs) and (super 230) Th normalized fluxes indicate higher productivity during the Last Glacial Maximum than during the Holocene, which is in agreement with other studies from this oceanographic region. In the Timor Sea the MARs indicate higher productivity during the Last Glacial Maximum, however the (super 230) Th normalized fluxes show no change. These results imply that post- or syn- depositional addition of lateral sediment may be a significant factor in the Timor Sea. Focusing factors derived from the (super 230) Th data support this theory, where values are Psi = >15 during the LGM, Psi = >12 at times during the deglaciation, and Psi = >9 during the Holocene. We offer three possible explanations for the high focusing factors in the Timor Sea: 1) deep-water current-enhanced deposition; 2) sea-level driven downslope movement on the Sahul Shelf; and/or 3) sediment supply from the Java arc-continent collision. We favor the 3 (super rd) explanation, sediment supply from the Java arc-continent collision, where lateral sediment focusing in the Timor Sea would have been sourced from the arc-continent collision. This explains the lack of sediment focusing in the Flores Sea that is shielded from the arc-continent collision, and receives significantly lower contributions of arc-continent collision derived sediment. This study highlights the importance of accurately reconstructing particle fluxes, and the advantages of the (super 230) Th normalized flux technique.
