Site 1195 (proposed Site CS-10A) is located on the Marion Plateau, ~60 km northeast of the south central Great Barrier Reef margin, at a water depth of 420 m (Fig. F1). The main objective at this site was to recover a lower Miocene to Holocene sedimentary section that provides a complete chronostratigraphy of the Neogene Marion Plateau depositional succession. Site 1195 is located at the intersection of regional seismic lines MAR15 (shotpoint 3505) and MAR04 (shotpoint 3928), 70 km east of the northern carbonate platform and 60 km north of the southern platform (Figs. F2, F3). Drilling at this site penetrated 521.2 m of hemipelagic sediment. Unlike other Leg 194 sites that were drilled at platform or platform proximal locations, the sediments at Site 1195 record a distal shelf facies. This distal facies records the combined effects of changes in platform shedding, detrital input, and pelagic sedimentation, all of which can be linked to changes in sea level and paleoceanography.
Successfully drilling a conformable distal shelf section provides an accurate chronostratigraphic framework to date seismic reflections and seismic sequence boundaries. The ages for these horizons can be correlated with other sites in the seismic grid to refine the age constraints in environments with lower chronostratigraphic resolution. All of the Marion Plateau megasequences occur at Site 1195 in a mostly conformable succession (Fig. F2), indicating that sedimentation was continuous overall throughout the Neogene. This observation supports the assumption that Site 1195 sediments provide the most complete stratigraphic record of all Leg 194 sites. The depositional environment of the sediments at Site 1195, particularly in the upper part of the drilled section, is strongly controlled by currents, as indicated by drift geometries seen on seismic data (Fig. F8 in the "Leg 194 Summary" chapter).
In addition to calibrating the chronostratigraphy of the regional seismic sequences, Site 1195 will provide information on paleoceanographic changes recorded by variations in sedimentologic composition, physical properties, and geochemistry.
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Ms 194IR-106