Deep Sea Drilling Project Leg 72: Southwest Atlantic paleocirculation and Rio Grande rise tectonics

Abstract

Research Article| May 01, 1981 Deep Sea Drilling Project Leg 72: Southwest Atlantic paleocirculation and Rio Grande rise tectonics PETER F. BARKER; PETER F. BARKER 1Department of Geological Sciences, University of Birmingham, P.O. Box 363, Birmingham B15 2TT, United Kingdom Search for other works by this author on: GSW Google Scholar RICHARD L. CARLSON; RICHARD L. CARLSON 2Department of Geophysics, Texas A&M University, College Station, Texas 77843 Search for other works by this author on: GSW Google Scholar DAVID A. JOHNSON; DAVID A. JOHNSON 3Department of Geology and Geophysics, Woods Hole Oceanographic Institution, Woods Hole, Massachusetts 02543 Search for other works by this author on: GSW Google Scholar PAVEL ČEPEK; PAVEL ČEPEK 4Bundesanstalt fur Geowissenschaften und Rohstoffe, Postfach 510153, 3000 Hannover 51, Federal Republic of Germany Search for other works by this author on: GSW Google Scholar WILLIAM COULBOURN; WILLIAM COULBOURN 5Deep Sea Drilling Project A-031, Scripps Institution of Oceanography, La Jolla, California 92093 Search for other works by this author on: GSW Google Scholar LUIZ A. GAMBÔA; LUIZ A. GAMBÔA 6Lamont-Doherty Geological Observatory, Columbia University, Palisades, New York 10964 Search for other works by this author on: GSW Google Scholar NORMAN HAMILTON; NORMAN HAMILTON 7Department of Geology, University of Southampton, Southampton SO9 5NH, United Kingdom Search for other works by this author on: GSW Google Scholar UBIRAJARA MELO; UBIRAJARA MELO 8Petrobras, Centro de Pesquisas e Desenvolvimento, Leopoldo a. Miguez de Mello (Cenpes), Cidade Universitaria, Quadra 7 Ilha do Fundao, CEP 21.910 Rio de Janeiro RJ, Brazil Search for other works by this author on: GSW Google Scholar CLAUDE PUJOL; CLAUDE PUJOL 9Department de Géologie et Oceanographie, University of Bordeaux I, 33405 Talence, France Search for other works by this author on: GSW Google Scholar ALEXANDER N. SHOR; ALEXANDER N. SHOR 10Lamont-Doherty Geological Observatory, Palisades, New York 10964 Search for other works by this author on: GSW Google Scholar ALEXEY E. SUZYUMOV; ALEXEY E. SUZYUMOV 11P. P. Shirshov Institute of Oceanology, USSR Academy of Sciences, Kraiskov St. 23, Moscow, USSR Search for other works by this author on: GSW Google Scholar LEONARD R. C. TJALSMA; LEONARD R. C. TJALSMA 12Cities Service Oil Company, Box 3908, 4500 S. 129th E. Avenue, Tulsa, Oklahoma Search for other works by this author on: GSW Google Scholar WILLIAM H. WALTON; WILLIAM H. WALTON 13Charles T. Main, Inc., Boston, Massachusetts 02199 Search for other works by this author on: GSW Google Scholar WOLFGANG WEISS WOLFGANG WEISS 14Bundesantalt für Geowissenschaften und Rohstoffe, Postfach 510153, 3000 Hannover 51, Federal Republic of Germany Search for other works by this author on: GSW Google Scholar Author and Article Information PETER F. BARKER 1Department of Geological Sciences, University of Birmingham, P.O. Box 363, Birmingham B15 2TT, United Kingdom RICHARD L. CARLSON 2Department of Geophysics, Texas A&M University, College Station, Texas 77843 DAVID A. JOHNSON 3Department of Geology and Geophysics, Woods Hole Oceanographic Institution, Woods Hole, Massachusetts 02543 PAVEL ČEPEK 4Bundesanstalt fur Geowissenschaften und Rohstoffe, Postfach 510153, 3000 Hannover 51, Federal Republic of Germany WILLIAM COULBOURN 5Deep Sea Drilling Project A-031, Scripps Institution of Oceanography, La Jolla, California 92093 LUIZ A. GAMBÔA 6Lamont-Doherty Geological Observatory, Columbia University, Palisades, New York 10964 NORMAN HAMILTON 7Department of Geology, University of Southampton, Southampton SO9 5NH, United Kingdom UBIRAJARA MELO 8Petrobras, Centro de Pesquisas e Desenvolvimento, Leopoldo a. Miguez de Mello (Cenpes), Cidade Universitaria, Quadra 7 Ilha do Fundao, CEP 21.910 Rio de Janeiro RJ, Brazil CLAUDE PUJOL 9Department de Géologie et Oceanographie, University of Bordeaux I, 33405 Talence, France ALEXANDER N. SHOR 10Lamont-Doherty Geological Observatory, Palisades, New York 10964 ALEXEY E. SUZYUMOV 11P. P. Shirshov Institute of Oceanology, USSR Academy of Sciences, Kraiskov St. 23, Moscow, USSR LEONARD R. C. TJALSMA 12Cities Service Oil Company, Box 3908, 4500 S. 129th E. Avenue, Tulsa, Oklahoma WILLIAM H. WALTON 13Charles T. Main, Inc., Boston, Massachusetts 02199 WOLFGANG WEISS 14Bundesantalt für Geowissenschaften und Rohstoffe, Postfach 510153, 3000 Hannover 51, Federal Republic of Germany Publisher: Geological Society of America First Online: 01 Jun 2017 Online ISSN: 1943-2674 Print ISSN: 0016-7606 Geological Society of America GSA Bulletin (1981) 92 (5): 294–309. https://doi.org/10.1130/0016-7606(1981)92<294:DSDPLS>2.0.CO;2 Article history First Online: 01 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 PETER F. BARKER, RICHARD L. CARLSON, DAVID A. JOHNSON, PAVEL ČEPEK, WILLIAM COULBOURN, LUIZ A. GAMBÔA, NORMAN HAMILTON, UBIRAJARA MELO, CLAUDE PUJOL, ALEXANDER N. SHOR, ALEXEY E. SUZYUMOV, LEONARD R. C. TJALSMA, WILLIAM H. WALTON, WOLFGANG WEISS; Deep Sea Drilling Project Leg 72: Southwest Atlantic paleocirculation and Rio Grande rise tectonics. GSA Bulletin 1981;; 92 (5): 294–309. doi: https://doi.org/10.1130/0016-7606(1981)92<294:DSDPLS>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 In order to investigate South Atlantic paleocirculation and the tectonic and sedimentary history of the Rio Grande rise, D/V Glomar Challenger occupied four sites during Deep Sea Drilling Project (DSDP) Leg 72: Site 515 in the Brazil basin, Site 516 near the crest of the Rio Grande rise, and Sites 517 and 518 on the lower western flank of the rise.Site 515 recovered sediments deposited by Antarctic Bottom Water (AABW) entering the Brazil basin through the Vema channel. We penetrated 617 m of rapidly accumulated, terrigenous and siliceous muds and mudstones before encountering an unconformity spanning 20 to 25 m.y. between the late Oligocene and early Eocene. The hiatus brackets the time of the proposed onset of AABW flow in the southwestern Pacific at ∼37 m.y.; however, evidence in the sediments at Site 515 suggests the presence of bottom-water circulation in the Brazil basin by early Eocene time.Sites 517 and 518 recovered calcareous sediments deposited under the influence of AABW and North Atlantic Deep Water (NADW) within the Vema channel. At both sites, an increase in the abundance of the AABW indicator species N. umbonifera during the late Pliocene implies that AABW extended to significantly shallower depths at that time than it does today. Detailed carbonate analyses at Site 518 may extend the late Pleistocene climatic signal through the entire Pleistocene and perhaps into the Miocene.At Site 516, near the crest of the Rio Grande rise, we penetrated 1,250 m of dominantly calcareous sediments and 21 m of basaltic basement rocks of Santonian-Coniacian age. With the exception of some minor hiatuses in the middle and late Miocene, sedimentation at this site was continuous for the past 80 m.y. Magneto-stratigraphic and biostratigraphic control is excellent, and the section may therefore be useful as a stratigraphic reference. The Cretaceous-Tertiary boundary was recovered intact and is directly comparable with the Italian Gubbio section. This interval may also provide some new evidence pertaining to the proposed association between mass extinctions and geochemical anomalies at the boundary.The igneous basement rocks recovered at Site 516 are T-type Mid-Ocean Ridge basalts (MORB), similar to those found on Iceland, and are unlike the alkalic basalts exposed on Tristan da Cunha. Their chemistry, together with the occurrence of shallow-water fossils in vein fillings, suggests that these basalts were erupted on an anomalously shallow part of the Mid-Atlantic Ridge. A Santonian-Coniacian age for basement is inferred from the age of the overlying sediments and is consistent with the identification of magnetic anomalies 33 and 34 on the rise to the east of the site.The basal sediments and underlying volcanic basement recovered at Site 516 may provide constraints on the subsidence history of the Rio Grande rise. However, this history may have been complicated by a middle Eocene episode of tectonic and volcanic activity, as suggested by ash layers, volcaniclastic sediments, and slump blocks in the mid-Eocene sediment section. The occurrence of reef debris in this interval implies that the uppermost part of the rise was very shallow and perhaps subaerial during this time. 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.