Linked sequence development and global climate change: The Upper Mississippian record in the Appalachian basin

The character and relative stratigraphic position of paleoclimatic indicato rs within Upper Mississippian strata of southern West Virginia suggest a li nk between eustasy and patterns of continental- to global-scale atmospheric circulation. At the cyclothem scale, annual rhythms in marine facies, and paleovertisols and lacustrine carbonates in terrestrial units indicate that seasonal, semiarid climatic conditions prevailed during highstand prograda tion. In contrast, leached paleosols and coals that underlie sequence bound aries and occur within transgressive heterolithic facies are suggestive of humid climatic conditions during late highstand through early transgression . Milankovitch-band, glacial-interglacial cyclicity may explain both sequen ce development and the evidence for Late Mississippian climate fluctuations in the Appalachian: basin. Shifts from seasonal to humid climatic conditio ns are attributed to systematic variation in monsoonal circulation, whereby seasonal moisture became restricted to the equatorial belt during the lows tands of each similar to 400 k.y. glacial-interglacial cycle.