HR: 17:30h
AN: H54A-07    [Abstracts]
TI: Linked Sea Level and Climate Change at the Scale of Third-Order Stratigraphic Sequences During the Late Paleozoic
AU: * Huntoon, J E
EM: jeh@mtu.edu
AF: Michigan Technological University, Department of Geological Engineering and Sciences, 1400 Townsend Drive, Houghton, MI 49931
AU: Dubiel, R F
EM: rdubiel@usgs.gov
AF: U.S. Geological Survey, M.S. 939 P.O. Box 25046 Denver Federal Center, Denver, CO 80225
AU: Stanesco, J D
AF: Department of Natural Sciences, Red Rocks Community College, Denver, CO 80228
AB: Deposition of the Permian Cutler Group in and around the Paradox basin, at tropical (approximately 0 to 10 degrees north) paleolatitudes, was influenced by linked changes in sea-level and local climate at a variety of temporal scales. At the scale of 3rd-order depositional sequences (1 to 10 m.y.), relatively wet sub-humid to semiarid conditions were associated with sea-level highstands, and semiarid to arid conditions were associated with sea-level lowstands. Linked cycles of local climate and sea-level change previously identified within the Cutler Group occur at the scale of 4th- and 5th-order depositional sequences (0.01 to 1 m.y.). These shorter-term, higher-frequency cycles are superimposed on the longer-term, 3rd-order-scale cycles described here. The Paradox basin was a foreland basin located between the southwest side of the Uncompahgre uplift of the Ancestral Rocky Mountains and the western shoreline of Pangea. The Cutler Group consists primarily of clastic sedimentary rocks derived from two distinct source areas: the Uncompahgre uplift located to the northeast of the Paradox basin, and the marine shelf located to the west. When sea level was high and the climate was sub-humid to semiarid, Uncompahgre-derived feldspar- and mica-rich sand and mud was transported across much of the Paradox basin and deposited in extensive low-gradient fluvial channels, floodplains, and tidal mudflats. At the same time, limestones and quartz-rich sands were deposited on the marine shelf. When sea level was low and the climate was semiarid to arid, clastic influx from the Uncompahgre was reduced. At the same time subaerially exposed shelf sediments were reworked and transported southeastward into the Paradox basin by onshore winds, where they were deposited as eolian dunes and sandsheets. The unique positioning of the Paradox basin at tropical latitudes, between the tectonically active Uncompahgre uplift and the passive margin of Pangea during the waning stages of late Paleozoic, high-latitude, southern-hemisphere glaciation resulted in ideal conditions for preservation of a long-term record of linked cycles of local climate and sea-level change at a variety of scales.
DE: 9614 Paleozoic
DE: 1815 Erosion and sedimentation
DE: 1886 Weathering (1625)
DE: 1625 Geomorphology and weathering (1824, 1886)
SC: Hydrology [H]
MN: 2004 AGU Fall Meeting