[1] Since Last Glacial Maximum (23-19 ka), Earth climate warming and deglaciation occurred in two major steps (Bølling-Allerød and Preboreal), interrupted by a short cooling interval referred to as the Younger Dryas (12.5-11.5 ka B.P.). In this study, three cores collected in the central part of Pandora Trough (Gulf of Papua) have been analyzed, and they reveal a detailed sedimentary pattern at millennial timescale. Siliciclastic turbidites disappeared during the Bølling-Allerød and Preboreal intervals to systematically reoccur during the Younger Dryas interval. Subsequent to the final disappearance of the siliciclastic turbidites a calciturbidite occurred during meltwater pulse 1B. The Holocene interval was characterized by a lack of siliciclastic turbidites, relatively high carbonate content, and fine bank-derived aragonitic sediment. The observed millennial timescale sedimentary variability can be explained by sea level fluctuations. During the Last Glacial Maximum, siliciclastic turbidites were numerous when the lowstand coastal system was located along the modern shelf edge. Although they did not occur during the intervals of maximum flooding of the shelf (during meltwater pulses 1A and 1B), siliciclastic turbidites reappear briefly during the Younger Dryas, an interval when sea level rise slowed, stopped, or perhaps even fell. The timing of the calciturbidite coincides with the first reflooding of Eastern Fields Reef, an atoll that remained exposed for most of the glacial stages.

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A series of four intraslope basins linked by submarine channels in the northwestern Gulf of Mexico form part of a source-to-sink depositional system that starts in the headwaters of the Brazos and Trinity Rivers and terminates in a ponded intraslope basin offshore Texas-the Brazos-Trinity depositional system. The system is well imaged with 3D seismic data, and two of the basins have been drilled, with three Integrated Ocean Drilling Program wells and two geotechnical wells. Using an integrated approach, we have combined seismiclitho-bio-tephro-stable-isotope-radioisotope stratigraphic methods, using both new and published results, to generate a millennial-scaleresolution chronostratigraphy for this system. Basins I through IV are infilled with about 62 km 3 of sand-rich sediments (~ 1.6 x 10 11 metric tons) transported by sediment gravity flows since the last interglacial (Oxygen Isotope Stage 5e). The bulk of the sediments, about 49 km 3 , were deposited within a short time period within Oxygen Isotope Stage 2, starting at 24.3 ka at the latest and ending at ~ 15.3 ka, before meltwater pulse 1A. Sediment accumulated in the slope basins at rates which varied over time between 1.4 and 55 million tons per year. Except for a short time interval when the Brazos River was diverted to the shelf edge at the head of Basin 1, sediment flux to deepwater was on average less than the present-day sediment discharge of the Trinity-Brazos-Sabine Rivers combined. In the period 24-15 ka the sediment sinks comprising the slope basins and shelf-margin delta can be balanced against the fluvial sources if their discharges are somewhat lower than present day, and if the contribution from incised-valley erosion was relatively small. The history of sedimentation on the slope basins is modulated by sea-level changes, but it is strongly influenced by basin topography and by the dynamics of delta development on the shelf. During peak high stands of sea level the slope area receives only pelagic sediments; during low sea-level stands, the sedimentation in each basin results from a complex combination between fluvial input at the head of the first basin, and the rate of subsidence/sedimentation causing basin topography. The ages of sediments in separate basins show that sedimentation occurs at the same time in multiple basins with trapping of sand in updip basins, while mud is preferentially deposited in downdip basins.

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