Unraveling the complex burial history of the Antrim formation in Michigan basin using paleomagnetism, rock magnetism and geochemistry

This paper presents an integrated paleomagnetic, rock magnetic and geochemical study of the Devonian Antrim shale in Michigan Basin. Specimens were obtained from two unoriented vertical cores (named St. Chester Krocker) sampled relative to a master specimen orientation line. Alternating field (AF) demagnetization experiments isolated lower coercivity component (LC) 0 ∼60 mT Krocker core corresponds Jurassic (170 Ma ± 25) magnetization. Higher components (HC) are unblocked 120 unlike LC components, occasionally exhibit stable unblocking temperature ranges (e.g., 150–450°C) higher AF (∼60–120 mT). HC unique certain members within with poorly resolved Middle Permian/Late Triassic magnetization Paxton member Late Pennsylvanian (305 10) Norwood. The well exhibited among all specimens slightly older (205 than core. Rock parameters indicate resides PSD/SD magnetite both components. Overall, magnetizations interpreted be chemical remanent (CRMs) residing SD which formed during hydrothermal activity cores. likely PSD/MD is have response fluid flow associated tectonic uplift and/or hydrocarbon migration. Petrographic observations mineral assemblages consistent mineralization baroque dolomite). Depleted δ18O data carbonate fractures mechanism. Consistent anisotropy susceptibility (AMS) lineations indicates either long-lived paleocurrent direction or far-field shortening originating neighboring Acadian orogeny. Inorganic geochemistry that paramagnetic Fe-rich clays carry AMS signal. Lastly, evaluation origin chalcopyrite monazite performed through provenance analysis. These minerals attributed however, strong evidence suggests some fraction these grains sourced Peninsula.