Paleozoic Carbonate Stacking Patterns in Idaho, U.S.A.*

By

Peter E. Isaacson¹, Michael C. Pope², Isabel P. Montanez³, and Liselle Batt⁴

Search and Discovery Article #50026 (2005)

Posted November 10, 2005

*Oral Presentation at Rocky Mountain Section AAPG Annual Meeting, Jackson, Wyoming, September 24-26, 2005. Appreciation is expressed to Lyn George, Technical Program Chair, and Don French, for encouraging the authors to submit this presentation. Presentations on related subjects are by Abplanapl et al. (2005) and Batt et al. (2005).

Click to view presentation in PDF format.

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

General Setting 

•      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

•      Coeval unstudied organic skeletal buildups (“reefs”) on paleo-shelf (Pahsimeroi Valley) yielding to gravity-flow    
     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