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Abstract: Contrasting Thermal Histories of the Early Mesozoic Newark and Taylorsville Basins Based on Borehole and Surface Vitrinite Reflectance: Basin-Wide Conductive vs. Advective Effects

MALINCONICO, MARYANN L.

The research will test 1) previous thermal history models of the Jurassic-Triassic Newark rift basins, eastern US, and 2) current hydrologic models of advective / conductive heat flow in continental rift basins using vitrinite reflectance. Previous thermal models of the Newark basin include a high thermal pulse / hydrothermal event associated with the synrift igneous event of 200 Ma or a post-rift hydrothermal event at ca. 180 Ma. Initial vitrinite reflectance data from one borehole in the middle of the Newark basin show an inverted temperature structure that may be due to migrating metalliferous brines. However, in the contemporaneous Taylorsville basin, kinetic modeling of reflectance data from five boreholes indicate that, except near the border fault, sediment maturation patterns can be attained just by burial heating under a sustained conductive gradient of 40 degrees C/km. The Taylorsville paleo-maximum thermal structure is that predicted by hydrologic models of rift basin thermal evolution.

The research plan is to collect vitrinite reflectance data on remaining cores and cuttings and expand the limited published Newark surface reflectance data. The Newark/Taylorsville basins are part of the Early Mesozoic Newark rift system that formed during the breakup of Pangaea and the opening of the Atlantic. They provide an easily accessible laboratory for the study of integrated lacustrine stratigraphic and thermal history of continental rift basins that in many parts of the world are still currently active or buried offshore. Rift basins with lacustrine source rocks are targets of petroleum exploration: understanding the thermal evolution of these high heat flow settings and its effect on the maturation of the source rocks is important to the prediction of timing of petroleum generation relative to trap formation.

AAPG Search and Discovery Article #90940©1997 AAPG Foundation Grants-in-Aid