CONTRASTING THERMAL EVOLUTION OF THE NEWARK AND TAYLORSVILLE BASINS: INHERITED ALLEGHANIAN HEAT FLOW AND CLIMATE-INFLUENCED HYDROSTRATIGRAPHY
The contrasting syn- to early post-rift thermal evolution of the Newark (NY/NJ/PA) and Taylorsville (VA) basins, based on recent borehole and surface vitrinite reflectance measurements combined with published cooling data, indicate material differences in basement heat flow and basin hydrostratigraphy. Basal basin heat flow is a relict of position relative to the Alleghanian orogenic metamorphic/ thermal axis, which was also the locus of post-orogenic collapse. The Taylorsville basin is located on the metamorphic 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. The interbasin differences in advective heat flow patterns are due to latitudinal climate influence on basin syn-rift coarse sedimentation and resulting hydrostratigraphic architecture.
Change in stress regime due to post-rift structural inversion (~180 Ma) produced transient advective events and exhumation that both cooled the basin-scale groundwater systems and variably eroded 0.4-3.1 km from the Taylorsville basin and >6 km from parts of the Newark basin.