Anomalous Thermal Indicators from the Aughigenic Minerals in Upper Paleozoic Strata of the Michigan Basin
Indications of anomalous paleo-temperatures exist in strata of the Michigan basin, USA. The thermal history of the basin was investigated through identification and analysis of authigenic components in two Upper Paleozoic strata, the Devonian Dundee Formation and Mississippian Marshall Sandstone. Formation conditions for diagenetic phases in both units were estimated through a variety of means and compared to conditions expected for a simple burial model. Authigenic clays identified in the Marshall via X-ray diffraction are expected to have formed at temperatures above what would have been produced by burial alone. Stable isotope and fluid inclusion analysis indicate the same for secondary carbonates in the Dundee. K-Ar age dating of Marshall authigenic illite provide ages of approximately 280 Ma. This age may reflect an illite formation period in the Permian or may be an integrated age representing multiple periods of illitization. Dolomite in the Dundee and illite in the Marshall are likely to have formed under hydrothermal conditions. The results of this study are part of a larger body of evidence that suggests episodic and extensive hydrothermal events have influenced the thermal history of the Michigan basin. These events are due to the reactivation of faults in the Proterozoic rift that underlies the basin and maybe related to thermal convection within the igneous rift body or Appalachian tectonic events.
AAPG Datapages/Search and Discovery Article #90218 © 2015 Eastern Section Meeting, Indianapolis, Indiana, September 20-22, 2015