Rb-Sr and Sm-Nd isotopic study of the Glen Mountains layered complex: Initiation of rifting within the southern Oklahoma aulacogen

Research Article| January 01, 1988 Rb-Sr and Sm-Nd isotopic study of the Glen Mountains layered complex: Initiation of rifting within the southern Oklahoma aulacogen David D. Lambert; David D. Lambert 1Department of Geology, Box 30798, Texas Christian University, Fort Worth, Texas 76129 Search for other works by this author on: GSW Google Scholar D. M. Unruh; D. M. Unruh 2U.S. Geological Survey, MS 963, Box 25046, Federal Center, Denver, Colorado 80225 Search for other works by this author on: GSW Google Scholar M. Charles Gilbert M. Charles Gilbert 3Department of Geology, Texas A&M University, College Station, Texas 77843 Search for other works by this author on: GSW Google Scholar Geology (1988) 16 (1): 13–17. https://doi.org/10.1130/0091-7613(1988)016<0013:RSASNI>2.3.CO;2 Article history first online: 02 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 David D. Lambert, D. M. Unruh, M. Charles Gilbert; Rb-Sr and Sm-Nd isotopic study of the Glen Mountains layered complex: Initiation of rifting within the southern Oklahoma aulacogen. Geology 1988;; 16 (1): 13–17. doi: https://doi.org/10.1130/0091-7613(1988)016<0013:RSASNI>2.3.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 SocietyGeology Search Advanced Search Abstract Rb-Sr and Sm-Nd isotopic data for rocks and minerals of the Glen Mountains layered complex (GMLC), a midcontinent mafic layered intrusion in the Wichita Mountains of southwestern Oklahoma, constrain the time of initiation of rifting within the southern Oklahoma aulacogen and provide information on the chemistry of the early Paleozoic mantle. Four whole-rock samples define a Rb-Sr isochron corresponding to a maximum crystallization age of 577 ±165 Ma and an initial Sr isotopic composition of 0.70359 ±2. These whole-rock analyses do not define a Sm-Nd isochron; rather, they display a significant range in initial Nd isotopic composition (εNd = 3.63-5.35). A three-point Sm-Nd mineral-whole-rock (internal) isochron for an anorthositic gabbro provides a crystallization age of 528 ±29 Ma. These data suggest that the GMLC was emplaced into the southern Oklahoma aulacogen during the initial phase of rifting along the southern margin of the North American craton in the early Paleozoic. This Sm-Nd internal isochron age is within analytical uncertainty of U-Pb zircon ages for granites and rhyolites from the Wichita Mountains; therefore, mafic and felsic magmatism may have been contemporaneous within the rift during the early stages of development. Hybrid rocks and composite dikes in the Wichita Mountains provide field evidence for contemporaneous mafic and felsic magmas. Initial Sr and Nd isotopic data suggest that magmas parental to the GMLC were derived from a depleted mantle source. However, Nd isotopic data for the GMLC plot distinctly below data for the depleted mantle source cited by DePaolo and thus suggest that the parental magmas of the GMLC were either contaminated by Proterozoic crust of the southern midcontinent or were derived from a heterogeneous mantle source region that had variable initial Nd isotopic compositions. 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.