Abstract

Rock magnetic variations record cyclicity within lithologically homogeneous basinal lime mudstones of the Lower Cretaceous San Angel Limestone, northeastern Mexico. Variations in ferromagnetic mineral concentrations, as measured by anhysteretic remanent magnetization (ARM), occur at frequencies consistent with Milankovitch orbital rhythms. Magnetic mineral compositions, grain-size distributions, and grain shapes from digested samples are congruent with far-traveled atmospheric dust. Prevailing winds and the proximity of the Cretaceous basin to an African eolian source support the encoding of orbitally modulated changes in wind intensity or source-area aridity. ARM measurements offer great potential to calibrate the pace of depositional processes in carbonates and to investigate high-frequency orbitally driven climate change in basinal strata throughout geologic time.

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