SILLS INTRUDED INTO MARINE SEDIMENTS CAUSES ORGANIC GEOCHEMICAL CHANGES: MIOCENE SILLS IN THE SANTA MONICA MOUNTAINS PRELIMINARY RESULTS

Recent studies have highlighted the importance of geologic settings involving skills emplaced in organic-rich sediments and sedimentary rocks, linking the associated organic metamorphism to large scale carbon releases, major climate events, mass extinctions, and thermodynamically generated petroleum. In this work, we investigate such a setting in the western Santa Monica mountains, where marine sediments were intruded by sills during the Miocene, then subsequently lithified, uplifted, and exposed. the presented work represents preliminary findings of the project. We identified and mapped exposures of sill-intruded wall rocks, collected rock samples from the contact aureoles, and conducted organic geochemical analyses. Samples were crushed, extracted using a soxhlet extractor, and analyzed by gas chromatography-mass spectrometry(GC-MS) for n-alkanes, polycyclic aromatic hydrocarbons(PAHs), and biomarkers (Seranes and hopanes). The analytical results were used to evaluate carbon release, atypical petroleum generation, and contact metamorphic changes to sedimentary organic matter in the Santa Monica Mountains , with the ultimate goal of improving understanding of the process associated with these geologic settings in general.