However, the bulk mineralogy suggests that either a change in the source of the terrigenous material or a change in the weathering regime of the source region took place over time. A major decrease in the interstitial water salinity and chloride content occurs below 500 mcd, corresponding to the top of the interval of highest methane values, the appearance of higher order hydrocarbons, changes in lithologic color, and changes in physical properties. This suggests that hydrocarbon and freshwater signals may have migrated laterally and that the other sedimentary changes are a diagenetic response to this change in environment. Benthic foraminifers are generally few but become more abundant in the lower part of the section. However, we found no clear evidence for reworked benthic foraminifers from the shelf and upper slope.
Planktonic foraminifers are abundant and well preserved.
The Miocene section has relatively constant rates. Overall, Site 1146 provides one of the most continuous Neogene sections ever recovered by the Ocean Drilling Program. This site will enable the reconstruction of monsoon proxies that can be used to test hypotheses about the late-Miocene intensification of the Asian summer monsoon and its relationship to tectonic events.