Lacustrine organic sedimentation, organic metamorphism and thermal history of selected early Mesozoic Newark Supergroup basins, eastern United States of America

This dissertation, using organic petrology techniques, examines thermal evolution and organic facies among eastern North American early Mesozoic rift basins. It demonstrates geographic variability in (1) both advective heatflow distribution and organic deposition due to latitudinal climatic influence on elastic sediment deposition, hydrostratigraphy, and lakeshore vegetation, and (2) basement heatflow due to basin position within the late Paleozoic Alleghanian orogen.; The lacustrine organic facies study (>750 core samples) in black shales of the paleoequatorial Triassic Richmond basin and in Jurassic lake cycles of the tropical Newark basin addresses contradictory published results of relative contribution of woody plant macerals. Newark basin woody maceral (vitrinite) sedimentation shows a strong relation to precipitation and distance from line sources in climatically-forced lake cycles: vitrinite increases at any single location with lake expansion but is scarce in deep lake microlaminated black shales due to distance from shore. Autochthonous kerogen is algal detritus, exhibiting progressive degradation to bacterially-derived amorphous organic matter (AOM) with increasing depth of lake and oxygenated epilimnion. On the other hand, in the Richmond basin, the variety of autochthonous and allochthonous maceral assemblages indicates depositional control by deltaic/turbidite point sources.; New borehole vitrinite reflectance data add a third dimension to published Newark thermal history studies, based mostly on surface samples. Differences in basement heatflow between the Newark and paleoequatorial Taylorsville basins are now attributed to location relative to the Alleghanian orogenic metamorphic axis which was also the locus of post-orogenic collapse. The Taylorsville basin is located on that axis and had a background geotherm of ∼45°C/km, modified by a syn-rift gravity-driven groundwater system producing crossbasinal variation in geothermal gradient (40–55°C/km). The Newark basin, west of the metamorphic axis, had a background gradient of ∼25°C/km. Syn-rift steady state heated groundwater flow through basal basin fluvial strata conductively heated overlying formations to ∼35°C/km. These interbasin differences in advective modification of basement heatflow are due to latitudinal climate influence on basin syn-rift coarse sedimentation and resulting hydrostratigraphic architecture.; Post-rift structural inversion produced transient advective heatflow anomalies and variable exhumation with 0.4–3.1 km eroded from the Taylorsville basin and >6 km from parts of the Newark basin.