GEOLOGIC EVOLUTION OF THE BEARTOOTH MOUNTAINS, MONTANA AND WYOMING

Abstract

Research Article| September 01, 1959 GEOLOGIC EVOLUTION OF THE BEARTOOTH MOUNTAINS, MONTANA AND WYOMING: PART 3. GARDNER LAKE AREA, WYOMING RAE L HARRIS, JR. RAE L HARRIS, JR. DEPARTMENT OF GEOLOGY, TEXAS TECHNOLOGICAL COLLEGE, LUBBOCK, TEXAS Search for other works by this author on: GSW Google Scholar GSA Bulletin (1959) 70 (9): 1185–1216. https://doi.org/10.1130/0016-7606(1959)70[1185:GEOTBM]2.0.CO;2 Article history received: 27 May 1958 first online: 02 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation RAE L HARRIS; GEOLOGIC EVOLUTION OF THE BEARTOOTH MOUNTAINS, MONTANA AND WYOMING: PART 3. GARDNER LAKE AREA, WYOMING. GSA Bulletin 1959;; 70 (9): 1185–1216. doi: https://doi.org/10.1130/0016-7606(1959)70[1185:GEOTBM]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 The Gardner Lake area is one of the key areas being studied in detail in the Beartooth Mountains, Montana and Wyoming. Foliation, compositional banding, and rock units indicate open southward-plunging folds traceable through metasediments and migmatites into granitic gneisses. The attitude of axial-plane foliation in highly contorted metasediments is found also in foliation trends of the gneisses. Complete gradations from metasediments to pink leucocratic gneiss are indicated by distribution of mappable units, abundance and composition of feldspars and ferromagnesian minerals, percentage and character of rounded and overgrown zircons, length-width ratios of zircons, and variations in chemical analyses. Replacement in situ by hot alkaline solutions seems the most likely origin for the granitic gneisses. Boudinage and rotation of amphibolite blocks within highly contorted feldspathized strata denote regional metamorphism prior to granitization. Mafic intrusive bodies are pregranitization, penegrantization, and postgranitization in age, and their major trends, northwest and northeast, suggest that the present topographic expression is controlled by structural elements developed during feldspathization. Seven K-A and Rb-Sr ages on widely dispersed micas and feldspars indicate this event as 2.7 billion years ago. 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.