The significance of fission-track ages of apatite in relation to the tectonic history of the Front and Sawatch Ranges, Colorado

Research Article| March 01, 1980 The significance of fission-track ages of apatite in relation to the tectonic history of the Front and Sawatch Ranges, Colorado BRUCE BRYANT; BRUCE BRYANT 1U.S. Geological Survey, Denver, Colorado 80225 Search for other works by this author on: GSW Google Scholar C. W. NAESER C. W. NAESER 1U.S. Geological Survey, Denver, Colorado 80225 Search for other works by this author on: GSW Google Scholar Author and Article Information BRUCE BRYANT 1U.S. Geological Survey, Denver, Colorado 80225 C. W. NAESER 1U.S. Geological Survey, Denver, Colorado 80225 Publisher: Geological Society of America First Online: 01 Jun 2017 Online ISSN: 1943-2674 Print ISSN: 0016-7606 Geological Society of America GSA Bulletin (1980) 91 (3): 156–164. https://doi.org/10.1130/0016-7606(1980)91<156:TSOFAO>2.0.CO;2 Article history First Online: 01 Jun 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation BRUCE BRYANT, C. W. NAESER; The significance of fission-track ages of apatite in relation to the tectonic history of the Front and Sawatch Ranges, Colorado. GSA Bulletin 1980;; 91 (3): 156–164. doi: https://doi.org/10.1130/0016-7606(1980)91<156:TSOFAO>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 Fission-track ages of apatite in the Mount Evans area of the Front Range show that the Late Cretaceous 100 °C isotherm, which was 4 km below the sea floor, is now at an altitude of 3.5 km. Assuming a geothermal gradient of 25 °C per kilometre, the projected level of the latest Cretaceous sea floor, represented by the Fox Hills Sandstone, is at an altitude of 7.5 km, about 3.2 km above the top of Mount Evans, and the structural relief from that projection of the Fox Hills on the crest of the Front Range uplift to the deepest part of the Denver Basin to the east is 6.5 km.Ages of apatite in Precambrian rock along the Elkhorn fault on the west margin of the Front Range uplift show that in the area of maximum stratigraphic displacement the fault must have a very low dip and that the east margin of the Paleocene South Park basin must have been nearby.Ages in the Sawatch Range suggest that significant uplift occurred during or after Eocene time. Ages on the east side of the range reflect development of the Arkansas Valley graben and concomitant uplift of the east margin of the modern Sawatch Range in Miocene time. This content is PDF only. Please click on the PDF icon to access. 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.