Structural geology and geochronology of subduction complexes along the margin of Gondwanaland: New data from the Antarctic Peninsula and southernmost Andes

Research Article| November 01, 1992 Structural geology and geochronology of subduction complexes along the margin of Gondwanaland: New data from the Antarctic Peninsula and southernmost Andes ANNE M. GRUNOW; ANNE M. GRUNOW 1Department of Earth Sciences, University of Oxford, Oxford OX1 3PR United Kingdom Search for other works by this author on: GSW Google Scholar IAN W.D. DALZIEL; IAN W.D. DALZIEL 2Institute for Geophysics, University of Texas at Austin, Austin, Texas 78712 Search for other works by this author on: GSW Google Scholar T. MARK HARRISON; T. MARK HARRISON 3Department of Earth and Space Sciences, University of California at Los Angeles, Los Angeles, California 90024 Search for other works by this author on: GSW Google Scholar MATTHEW T. HEIZLER MATTHEW T. HEIZLER 3Department of Earth and Space Sciences, University of California at Los Angeles, Los Angeles, California 90024 Search for other works by this author on: GSW Google Scholar Author and Article Information ANNE M. GRUNOW 1Department of Earth Sciences, University of Oxford, Oxford OX1 3PR United Kingdom IAN W.D. DALZIEL 2Institute for Geophysics, University of Texas at Austin, Austin, Texas 78712 T. MARK HARRISON 3Department of Earth and Space Sciences, University of California at Los Angeles, Los Angeles, California 90024 MATTHEW T. HEIZLER 3Department of Earth and Space Sciences, University of California at Los Angeles, Los Angeles, California 90024 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 (11): 1497–1514. https://doi.org/10.1130/0016-7606(1992)104<1497:SGAGOS>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 ANNE M. GRUNOW, IAN W.D. DALZIEL, T. MARK HARRISON, MATTHEW T. HEIZLER; Structural geology and geochronology of subduction complexes along the margin of Gondwanaland: New data from the Antarctic Peninsula and southernmost Andes. GSA Bulletin 1992;; 104 (11): 1497–1514. doi: https://doi.org/10.1130/0016-7606(1992)104<1497:SGAGOS>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 Subduction complexes along the Andean margin in central and southern Chile yield mid-Paleozoic to lower Mesozoic ages, yet they crop out within 100 km of the modern trench that shows evidence of active accretion along much of its length. The scarcity of uplifted subduction-complex rocks younger than mid-Mesozoic along the Chilean margin and in parts of the Scotia Arc suggests to us that these old, crystalline rocks, uplifted in the Triassic and Jurassic, represent a boundary in the forearc beyond which tectonic erosion does not easily occur.Greenschist-, blueschist-, and amphibolite-facies subduction-complex rocks from the Scotia Arc were originally thought to be a simple continuation of the subduction complexes in Chile. Based on new 40Ar/39Ar ages, the Scotia Arc subduction complexes reveal a complex history related to distinct local tectonic events and are not a simple continuation of the old accretionary prism in Chile. Structural and metamorphic analysis indicates the earliest and most penetrative deformation in the subduction complexes around the Scotia Arc occurred at some depth in a subduction zone or zones, certainly below the brittle-ductile transition, and in some cases under blueschist-facies conditions. We believe that the early subduction-related deformation and metamorphism in the greenschist- and blueschist-facies rocks of the Scotia Arc to be overprinted by mid-Cretaceous transpression along the South America-Antarctica plate boundary in the case of Elephant Island, transpression and subsequent localized transtension in the earliest Cenozoic in the case of the Darwin Complex, a mid-Cenozoic spreading-rate change in the case of Smith Island, and early Neogene initiation of Drake Passage opening/Shackleton Fracture Zone formation in the case of the Gibbs Island subgroup. 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.