255-2 Low-Temperature Thermochronology Using Detrital And Basement Apatite Reveals Possible Mechanism For Initiation of Cratonic Basin Subsidence, Michigan Basin, Michigan, USA

Session: Broad Applications of Thermochronology to Understanding Geologic Rates and Processes Through the Sedimentary Record

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Abstract:

The mechanism for the formation of cratonic basins has been an area of debate for decades. Multiple tectonic and geodynamic models have been invoked to address the mechanism for initiation of subsidence in the stable cratonic crust, including cyclical delamination by hotspots and crustal thinning from rifting, but there has been little shallow-crustal data to support or reject these models.  Here we present a low-temperature thermal history of the upper ~6 km of crust of the Michigan Basin, a cratonic basin in North America, that we use to test the viability of potential subsidence mechanisms. New thermochronologic dates presented here come from 14 (U-Th)/He apatite (AHe) and 7 Apatite Fission Track (AFT) samples collected from 6 cores from across the Michigan Basin from crystalline basement and reset or partially reset strata: 3 samples from basement (depth of 1411 m, 1547m, and 4728 m); 2 Cambrian samples from the Galesville Formation (dpeth of 3340 m) and Mt. Simon Sandstone (1398 m); 2 samples from Ordovician St. Peter’s Formation ( depth of 4209 m and 3300 m); and 1 sample from the Mississippian Berea sandstone (depth of 542 m). The basement AHe ages show two stages of rapid cooling at 98.6 Ma (1547 m) and 4.1 Ma (1411 m) following a prolonged period in the partial retention zone (PRZ) shown by a steep date-eU trend in the Cambrian sample (1398 m). AFT dates similarly show central ages (77.1 to 17.5 Ma) for deeper core samples (>1500 m), and older central ages (123.4 Ma to 359.7 Ma) for shallower samples (<1500 m). These trends indicate that stratigraphic samples have been fully or partially reset. HeFTy models of the basin data show that there is a period of heating starting ~300 Ma that exceeds the heating associated with burial depth. The timing of reheating aligns with the passing of North American Craton over LLSVP and supports the previously proposed mechanism (Wang and Cao et al., 2023) that cratonic basins are generated by cyclical partial lithospheric delamination by plume underplating.  Heating is followed by rapid cooling to modern temperatures around 50 Ma. The reheating signal is most clearly resolved in deeper samples, but the cooling can be seen across all sample depths throughout the basin.

Geological Society of America Abstracts with Program. Vol. 57, No. 6, 2025

doi: 10.1130/abs/2025AM-4490

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