(Table 1) Organic geochemistry of ODP Site 128-799A

Pyrolysis techniques were used to characterize the organic matter contained within the penetrated section and to assess the presence of heavy hydrocarbon shows. The Rock-Eval data indicate a change in organic hydrogen enrichment within the middle Miocene sequence. It appears that the level of organic enrichment may be controlled by sedimentation rate, while the organic hydrogen enrichment, as shown in the hydrogen index, may reflect differences in preservation potential. Higher sedimentation rates would result in higher organic carbon contents. Higher hydrogen index values would reflect higher degrees of organic preservation resulting from more restricted circulation. […]