Peru-Chile Trench Sediments and Sea-Floor Spreading

Abstract

Research Article| May 01, 1970 Peru-Chile Trench Sediments and Sea-Floor Spreading DAVID W SCHOLL; DAVID W SCHOLL Office of Marine Geology, U.S. Geological Survey, Menlo Park, California 94025 Search for other works by this author on: GSW Google Scholar MARK N CHRISTENSEN; MARK N CHRISTENSEN Department of Geology and Geophysics, University of California, Berkeley, California 94720 Search for other works by this author on: GSW Google Scholar ROLAND VON HUENE; ROLAND VON HUENE Office of Marine Geology, U.S. Geological Survey, Menlo Park, California 94025 Search for other works by this author on: GSW Google Scholar MICHAEL S MARLOW MICHAEL S MARLOW Office of Marine Geology, U.S. Geological Survey, Menlo Park, California 94025 Search for other works by this author on: GSW Google Scholar Author and Article Information DAVID W SCHOLL Office of Marine Geology, U.S. Geological Survey, Menlo Park, California 94025 MARK N CHRISTENSEN Department of Geology and Geophysics, University of California, Berkeley, California 94720 ROLAND VON HUENE Office of Marine Geology, U.S. Geological Survey, Menlo Park, California 94025 MICHAEL S MARLOW Office of Marine Geology, U.S. Geological Survey, Menlo Park, California 94025 Publisher: Geological Society of America Received: 29 Sep 1969 First Online: 02 Mar 2017 Online ISSN: 1943-2674 Print ISSN: 0016-7606 Copyright © 1970, The Geological Society of America, Inc. Copyright is not claimed on any material prepared by U.S. government employees within the scope of their employment. GSA Bulletin (1970) 81 (5): 1339–1360. https://doi.org/10.1130/0016-7606(1970)81[1339:PTSASS]2.0.CO;2 Article history Received: 29 Sep 1969 First Online: 02 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn Email Permissions Search Site Citation DAVID W SCHOLL, MARK N CHRISTENSEN, ROLAND VON HUENE, MICHAEL S MARLOW; Peru-Chile Trench Sediments and Sea-Floor Spreading. GSA Bulletin 1970;; 81 (5): 1339–1360. doi: https://doi.org/10.1130/0016-7606(1970)81[1339:PTSASS]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 hypotheses of sea-floor spreading and plate tectonics require the removal of sediment from oceanic trenches either by crustal underthrusting or by folding against the base of a continental or insular margin. Accordingly, over a period of time the volume of sediment removed by way of spreading must be equal to the difference between the observable volume of undeformed terrigenous deposits in a trench and the volume contributed to it by continental erosion. To assess possible sediment loss from the central Chilean segment (23°–44° S.) of the Peru-Chile Trench, we have compared the volume of terrigenous deposits overlying the land, the continental margin, and filling the trench with that expected from continental denudation.Our data indicate that an episode of sediment removal occurred at the base of the margin and adjacent deep-sea floor in Late Cretaceous and perhaps earlymost Tertiary time and may imply spreading. Nearly 100 × 103 km3 of deposits of Tertiary age, chiefly Eocene to Pliocene, have accumulated on the margin, and perhaps an additional 5 × 103 km3 in the trench. This amount of offshore sediment could be supplied by fairly low rates (3 cm/103 yrs) of Tertiary erosion. However, many uncertainties in our denudation-sedimentation budget make it impossible to determine whether or not sediment reaching the base of the margin was removed tectonically in Tertiary time.Between 27° and 44° S., the trench contains nearly 70 × 10s km3 of turbidite deposits that we believe accumulated during late Cenozoic periods of glacially lowered sea level. The volume of turbidites in the trench is virtually equal to that expected from continental erosion, which is estimated to have probably been no greater than 5 cm/103yr for the arid region between 27° and 31°, and 50 cm/103yr for the humid and partially glaciated region from 36° to 42°. During this time of rapid erosion and trench filling, magnetic data indicate that convergence of lithospheric plates was taking place below the trench at a rate between 5 and 10 cm/yr. If turbidite deposits were swept from the trench at these rates, then continental denudation must have been exceedingly rapid: 20–40 cm/103 yr for the arid zone, and 110–165 cm/103 yr for the partially glaciated region. If more conventional estimates of erosion are valid, then either (1) late Cenozoic underthrusting has not taken place (or at a rate much slower than that implied by geophysical data), or (2) underthrusting at the prescribed rates has not involved the removal of a significant volume of sediment from the trench. 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.