--> Abstract: Late Paleozoic Ice Volume Controls on the Paleoclimate and Stratigraphic Record of Southern Euramerica; #90063 (2007)

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Late Paleozoic Ice Volume Controls on the Paleoclimate and Stratigraphic Record of Southern Euramerica

 

Cecil, C. Blaine1, Frank T. Dulong1, Isabel Montanez2 (1) US Geological Survey, Reston, VA (2) University of California, Davis, CA

 

The late Paleozoic stratigraphic record from southern Euramerica documents paleoclimate changes that were coincident with, and linked to, global climate modes. Carbonates, orthoquartzites, and chert developed during a warm-mode in the early Devonian. Weak latitudinal climate gradients and feeble wind-driven circulation during the Middle Devonian warm mode resulted in organic-rich fine-grained sediments. Waning of the Devonian warm-mode (Famennian) lead to sea level fall, seasonal rainfall, continental red beds, and calcic-paleosols. Glaciogenic deposits, chemically reduced continental siliciclastics, abundant terrestrial organic matter, and intensely leached paleosols are coincident with a cool mode that persisted from the late Famennian into the mid-Visean (late Osagean). An abrupt change in sedimentation in the mid-Visean (late Osagean?) to carbonates, evaporites, and eolianites documents a shift to aridity associated with mid-Visean global warming and sea level rise. The onset of the mid-Carboniferous cool-mode is recorded in Serpukovian (late Chesterian) strata by sea level fall and a progressive stratigraphic increase in continental sediments and terrestrial organic matter. The Mid-Carboniferous cool-mode is linked to a humid paleoclimate that resulted in chemically reduced siliciclastics and coal during the Bashkirian and Moscovian. Kasimovian red beds, paleo-calcic-Vertisols, and sea level rise document a return to warm-mode dry conditions. Humid to dry-subhumid conditions recorded in Gzhelian cyclothems resulted in coal beds, chemically reduced siliciclastics, and nonmarine limestones respectively signaling the onset of Permian glaciation. Both intermediate-term and long-term changes in the Late Paleozoic stratigraphic record in the low latitudes of southern Euramerica are best explained by both sea level change and shifting atmospheric pressure belts in response to changes in ice-volume in the southern hemisphere.

 

AAPG Search and Discover Article #90063©2007 AAPG Annual Convention, Long Beach, California