Hauling field gear up Gothic Mountain…
Research Article| March 01, 1968 Pre-Pennsylvanian Stratigraphy and Paleotectonics of the San Juan Mountains, Southwestern Colorado D. L BAARS; D. L BAARS Dept. of Geology, Washington State University, Pullman, Washington Search for other works by this author on: GSW Google Scholar PAUL D SEE PAUL D SEE Independent, Warrenton, Oregon Search for other works by this author on: GSW Google Scholar Author and Article Information D. L BAARS Dept. of Geology, Washington State University, Pullman, Washington PAUL D SEE Independent, Warrenton, Oregon Publisher: Geological Society of America Received: 07 Oct 1966 Revision Received: 03 Apr 1967 First Online: 02 Mar 2017 Online ISSN: 1943-2674 Print ISSN: 0016-7606 Copyright © 1968, The Geological Society of America, Inc. Copyright is not claimed on any material prepared by U.S. government employees within the scope of their employment. GSA Bulletin (1968) 79 (3): 333–350. https://doi.org/10.1130/0016-7606(1968)79[333:PSAPOT]2.0.CO;2 Article history Received: 07 Oct 1966 Revision Received: 03 Apr 1967 First Online: 02 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn Email Permissions Search Site Citation D. L BAARS, PAUL D SEE; Pre-Pennsylvanian Stratigraphy and Paleotectonics of the San Juan Mountains, Southwestern Colorado. GSA Bulletin 1968;; 79 (3): 333–350. doi: https://doi.org/10.1130/0016-7606(1968)79[333:PSAPOT]2.0.CO;2 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGSA Bulletin Search Advanced Search Abstract A large northwest-trending graben-faulted anticline involving all pre-Pennsylvanian rocks is exposed in the core of the San Juan Mountains near Silverton, Colorado. The feature was formed before Late Cambrian time when younger Precambrian quartzites were extensively down-faulted into juxtaposition with the older Precambrian basement complex. The quartzites emerged topographically high and supplied local talus to Ignacio deposits (Late Cambrian) adjacent to the faults. Ignacio rocks do not cover the fault block, but thicken and become finer-grained away from the feature.As the Late Devonian seas advanced, the McCracken Sandstone Member of the Elbert Formation was deposited along the flanks of the structural feature, but apparently did not cross it. The upper Elbert intertidal dolomites were the first sediments to be deposited across the faulted fold where they lie directly on Precambrian quartzites. Latest Devonian or earliest Mississippian stromatolitic dolomites of the Ouray Formation overlie Elbert strata on the flanks of the old feature, and equivalent normal marine limestones are locally present within the down-faulted block.The Early Mississippian Leadville Formation thins abruptly onto the flanks of the graben-faulted anticline, where the lithologic aspect is one of stromatolitic dolomite formed in an inter-tidal zone. Within the graben, Leadville strata are thin or missing except as remnants in the overlying Molas regolith, suggesting that intense post-Leadville weathering removed those rocks across the regionally high structure. A small horst is present within the large graben where Pennsylvanian sedimentary rocks rest directly on upturned Precambrian quartzites. The graben was again down-faulted at some undetermined post-Desmoinesian time, for Middle Pennsylvanian beds are now in fault contact with Precambrian rocks along the flanking faults.A similar ancient fault block south of Ouray, Colorado, extends northwesterly into the sub-surface of the eastern Paradox basin. This feature parallels the nearby Uncompahgre uplift and may be genetically related to it. First Page Preview Close Modal You do not have access to this content, please speak to your institutional administrator if you feel you should have access.
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