Abstract An integrated thermal history study of the Beaufort-Mackenzie basin of northern Canada is underway using multiparameter data gathered as part of a twelve year petroleum systems research project. New and legacy percent vitrinite reflectance (%Ro) data for approximately 81 wells have been compiled and standardized in order to make maps and cross sections showing thermal maturity trends and to provide paleotemperature constraints for thermal models. Data were quality-assessed by comparing measured %Ro values with other temperature-sensitive indicators (Rock-Eval pyrograms, liptinite fluorescence, and degree of apatite fission track (AFT) thermal annealing) and inconsistent legacy %Ro data were reinterpreted in conjunction with new sample analyses. Extensive organic matter recycling is the major issue affecting data quality and interpretation whereas other factors such as sample caving and oil staining (%Ro suppression) are important but less significant. Multikinetic AFT thermochronology data were obtained for 60 (mainly core) samples from 25 key wells with standardized %Ro data to provide constraints on the timing and rates of burial and exhumation across the study area. Also, thermal maturity and shale compaction trends were used to estimate net erosion magnitudes related to multiple phases of Tertiary deformation and exhumation. Measured %Ro is highest in exhumed strata along the southern basin margin and lowest in thick Cenozoic strata offshore (north) on the Beaufort shelf. Thermally immature strata persist to depths of > 4 km and to temperatures > 100°C on the outer Beaufort shelf due to rapid deposition of the thick (> 2.5 km) Plio-Pleistocene Iperk Sequence. Shale compaction trends suggest that 0.5-2 km of postrift Tertiary strata have been eroded from southern and southeastern onshore areas. %Ro-based erosion estimates are more variable and can give much higher values (by a factor of 3 or 4) than the compaction-based estimates, particularly in the Tertiary fold belt of the western and southern areas of the basin. There is a discontinuous increase in maturity across the unconformity that separates Jurassic synrift and Permian prerift strata along the southern basin margin. In the area south of Richards Island, maturity trends suggest that up to 4 km of Permo-Triassic strata may have been eroded prior to the deposition of Jurassic sediments. In the Anderson Plain to the east, erosion has been more extensive and Devonian rocks lie near the surface. Thermal modeling of AFT data from a Devonian sample in the Kugaluk N-02 well (AFT age: 216 Ma) suggests that exhumation was well underway in the Triassic, possibly in association with the onset of rifting. Exhumation may have continued until the Early Cretaceous, followed by reburial under 1-2 km of Cretaceous-Cenozoic sediments that were removed subsequently by erosion. The %Ro data provide important maximum paleotemperature constraints for integrated thermal history models based on multikinetic, AFT thermochronological data collected for the synrift and postrift successions.

Ash-fusion characteristics of the Lower Kittanning seam (western Pennsylvania) can be related to environment of deposition. Non-slagging coals (coals with ashes that have ash-fusion temperatures [AFTs] in excess of 2,600°F) are associated with freshwater environments that occur toward the margins of the basin. Slagging coals (coals with ashes that melt at temperatures less than 2,200°F) occur in the central part of the basin, in areas overlain by shales that have been interpreted to have formed in a brackish environment. Trend-surface analysis indicates that whereas strong basinal trends do exist, locally variability can modify regional trends. High ash-fusion coals are associated with high clay (primarily kaolinite) contents, whereas low-fusion coals are associated with high pyrite and marcasite (and to a lesser extent, siderite) contents. Bivariate analysis of these data shows highly significant negative correlations between AFT and Fe 2 O 3 , pyrite, and siderite. Positive correlations exist between AFT and SiO 2 , Al 2 O 3 , TiO 2 , MgO, and K 2 O. Illite and kaolinite also correlate positively with AFT. An understanding of the oxide and mineral composition of the ash and the depositional environment of the peat can therefore be useful in the prediction of ash-fusion characteristics.