An end-member sensitivity analysis of vitrinite reflectance distributions for the COST G-2 well in the Georges Bank Basin

Abstract

Vitrinite reflectance (VR) is one of the most popular thermal indicators in basin analysis studies, with the mean values of the VR distribution data usually used for determining the thermal history of sediments. Abnormally high mean values, and thus abnormally high VR-derived paleoheat flux, may be recorded when recycled or highly oxidized vitrinite macerals are mixed in situ with virgin vitrinite. In this study end-member sensitivity analysis methods are applied to VR distribution data measured in the COST G-2 well in Georges Bank Basin, U.S.A., to investigate the mixing properties of the VR data. The modified VR data, obtained through a filtering procedure, are then used to generate a modified thermal history. A 1-D fluid flow/compaction model is employed for the basin's burial and thermal history inversion. Relative to the thermal history derived from the mean VR distribution data,the modified thermal history results in a lower paleoheat flux and paleotemperature and is consistent with other geological evidence and with the thermal history obtained from other thermal indicators such as Transmittance Color Index and Temperature Alteration Index.