Cratonic basins with reference to the Michigan basin

Abstract

Abstract Seafloor and passive margins gradually subside as a result of thermal contraction of the underlying lithosphere. Thermal subsidence is also an attractive mechanism for the Michigan basin. For subsidence to occur within this previously stable continental region, some mechanism is needed to heat the lithosphere and to reduce the buoyancy of the continental crust. Mechanical stretching of the lithosphere along with its crust does both at the same time. The ponding of plume material beneath the crust supplies heat, but does not directly thin the crust. The British Isles and the Congo basin provide analogies to the Michigan basin. Continental stretching before subsidence is evident within the British Isles and the Congo basin. Stretching is not obvious in Michigan, but undetected rifts extending from the Iapetus break-up margin may exist. A closed region of thin lithosphere beneath the Irish Sea may have trapped hot buoyant material from the Iceland plume; the Michigan basin may have trapped material from an Iapetus age plume near Montreal. Cratonic basins provide information on the tail of the subsidence curve, unlike more ephemeral oceanic crust and passive margins. The poorly resolved tails in the Michigan and the Congo basins are consistent with the time subsidence constant, c. 280 myr predicted by stagnant lid convection formalism.