Isotopic provenance of Paleogene sandstones from the accretionary core of the Olympic Mountains, Washington

Abstract

Research Article| February 01, 1992 Isotopic provenance of Paleogene sandstones from the accretionary core of the Olympic Mountains, Washington PAUL L. HELLER; PAUL L. HELLER 1Department of Geology and Geophysics, University of Wyoming, Laramie, Wyoming 82071 Search for other works by this author on: GSW Google Scholar ROWLAND W. TABOR; ROWLAND W. TABOR 2U.S. Geological Survey, 345 Middlefield Road, Menlo Park, California 94025 Search for other works by this author on: GSW Google Scholar JAMES R. O'NEIL; JAMES R. O'NEIL 3Department of Geological Sciences, University of Michigan, Ann Arbor, Michigan 48109-1063 Search for other works by this author on: GSW Google Scholar DAVID R. PEVEAR; DAVID R. PEVEAR 4Exxon Production Research Company, Houston, Texas 77252 Search for other works by this author on: GSW Google Scholar MUHAMMAD SHAFIQULLAH; MUHAMMAD SHAFIQULLAH 5Department of Geosciences, University of Arizona, Tucson, Arizona 85721 Search for other works by this author on: GSW Google Scholar NANCY S. WINSLOW NANCY S. WINSLOW 6Department of Geology and Geophysics, University of Wyoming, Laramie, Wyoming 82070 Search for other works by this author on: GSW Google Scholar Author and Article Information PAUL L. HELLER 1Department of Geology and Geophysics, University of Wyoming, Laramie, Wyoming 82071 ROWLAND W. TABOR 2U.S. Geological Survey, 345 Middlefield Road, Menlo Park, California 94025 JAMES R. O'NEIL 3Department of Geological Sciences, University of Michigan, Ann Arbor, Michigan 48109-1063 DAVID R. PEVEAR 4Exxon Production Research Company, Houston, Texas 77252 MUHAMMAD SHAFIQULLAH 5Department of Geosciences, University of Arizona, Tucson, Arizona 85721 NANCY S. WINSLOW 6Department of Geology and Geophysics, University of Wyoming, Laramie, Wyoming 82070 Publisher: Geological Society of America First Online: 01 Jun 2017 Online ISSN: 1943-2674 Print ISSN: 0016-7606 Geological Society of America GSA Bulletin (1992) 104 (2): 140–153. https://doi.org/10.1130/0016-7606(1992)104<0140:IPOPSF>2.3.CO;2 Article history First Online: 01 Jun 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn Email Permissions Search Site Citation PAUL L. HELLER, ROWLAND W. TABOR, JAMES R. O'NEIL, DAVID R. PEVEAR, MUHAMMAD SHAFIQULLAH, NANCY S. WINSLOW; Isotopic provenance of Paleogene sandstones from the accretionary core of the Olympic Mountains, Washington. GSA Bulletin 1992;; 104 (2): 140–153. doi: https://doi.org/10.1130/0016-7606(1992)104<0140:IPOPSF>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 SocietyGSA Bulletin Search Advanced Search Abstract Conventional modal sandstone data from Paleogene units of the Pacific Northwest are not precise enough to pinpoint source areas and constrain displacement histories of accreted sedimentary terranes. Isotopic provenance study, used in conjunction with traditional basin-analysis techniques, provides a powerful means of identifying source areas. Analysis of Rb-Sr data in both wholerock and detrital white micas of Paleogene sandstones from allochthonous units in the eastern core of the Olympic Mountains and coeval autochthonous sandstones from coastal Pacific Northwest shows that the Needles-Gray Wolf and Grand Valley lithic assemblages of the core came from the same source as sandstones of the Chuckanut Formation and Puget Group in northern Washington. The source of these units is isotopically distinct from the source for units farther south, such as the Tyee Formation in Oregon. Chemical compositions, conventional K-Ar age determinations, and oxygen- and hydrogen-isotope compositions of white micas support this conclusion.Similar analyses of sandstones from the Western Olympic lithic assemblage and the Yakutat terrane of southeastern Alaska suggest that these two units have a similar source, but that they differ slightly from sandstones of the eastern Olympic core and autochthonous Washington units.The overall composition of sandstones (lithic arkosic), and the very high initial-Sr values (>0.710), moderately high δ18O values (∼+9) and Mesozoic age for detrital white mica of Olympic core rocks and sandstone of the Yakutat terrane suggest a source in the high-rank metamorphic and plutonic rocks from the eastern part of the Omineca Crystalline Belt in southeastern British Columbia. Furthermore, rapid uplift of this source area during Eocene time is consistent with the depositional age of the Olympic rocks. Sediment derived from this source area was transported westward by major river systems that crossed the low-lying North Cascade Range and supplied the deposits of the autochthonous units of the northern Washington coast and the offshore equivalents before the latter were accreted to form the Olympic core.Limited data from the Yakutat terrane suggest that it lay offshore of southern British Columbia sometime during middle Eocene to early Oligocene time, consistent with paleomagnetic and some paleontologic interpretations, and subsequently migrated northward by plate motions. 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.