Paleozoic Carbonate Stacking Patterns in Idaho, U.S.A.*
Search and Discovery Article #50026 (2005)
Posted November 10, 2005
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1Dept. Geological Sciences, University of Idaho, Moscow, ID 83844-3022, phone: 208-885-7969, fax: 208-885-5724 ([email protected])
2Department of Geology, Washington State University, Pullman, WA 99164
3Department of Geology, University of California, Davis, CA 95616
4Geological Sciences, University of Idaho, Moscow, ID 83844-3022
• Over 12 km of Silurian-Pennsylvanian carbonates – significant accommodation
• Pre-Mississippian carbonates dolomitized
• Devonian “Alberta-style” buildups
• Early Mississippian flysch (western-derived) and carbonate progradation
• Late Mississippian glacio-eustacy
• Penn/Perm hydrozoan buildups
Early Paleozoic general depositional setting.
Lower Paleozoic stratigraphic column, representative of passive-margin deposition.
Early Paleozoic Passive Margin Tectonic Overview:
Pre-Silurian through Middle Devonian
• Passive margin
• Sediment and water loading provides accommodation.
• Early Silurian continental margin located at present Lost River Range front
organic skeletal buildups (“reefs”) on paleo-shelf (Pahsimeroi Valley) yielding
deposits (west of Lost River Range)
Late Paleozoic--Late Devonian through Permian--Tectonic Loading by Allochthons
• Tectonic highland appears in Late Devonian (Picabo Formation) – RM (equivalent) allochthon?
• Significant flysch trough begins, Early Mississippian.
• Carbonate bank builds from east.
• Tectonic loading and sediment loading continue accommodation.
• Second tectonic subsidence even in Late Mississippian