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doi:10.2204/iodp.proc.308.214.2009

Introduction

Integrated Ocean Drilling Program (IODP) Expedition 308 drilled Pleistocene sediments from the Gulf of Mexico in Brazos-Trinity IV and Ursa Basins (see the “Expedition 308 summary” chapter). The goal of the expedition was to measure in situ pore pressure in a normally pressured (Brazos-Trinity IV) and an overpressured (Ursa) basin and compare these data with geotechnical measurements on the cores. During the expedition, a link was established between overpressured sediments and slope failure, leading to important turbidity transport and deposits (Flemings et al., 2008). Here, we present X-ray diffraction (XRD) data from bulk sediment from two holes, one from Brazos-Trinity IV Basin (Hole U1320A) and one from Ursa Basin (Hole U1324B). XRD is an excellent tool to quickly identify mineral phases in the sediment and quantify their abundances. The ultimate goal of our research is to tie the trends observed in the bulk rock mineralogy with similar trends in grain size (Sawyer et al.), in situ pore pressures (Flemings et al., 2008; Long et al.), and mechanical behavior of the sediment (Long et al.). Our working hypothesis is that the amount and type of clay minerals present in the matrix of the mudstone from both basins will likely affect sediment behavior. This integration, however, will require additional data, in particular detailed mineralogy of the phyllosilicate fraction (i.e., clay minerals), which is beyond the scope of this data report.