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Geology of Santiago, Rábida, and Pinzón Islands, Galápagos

1974; Geological Society of America; Volume: 85; Issue: 11 Linguagem: Inglês

10.1130/0016-7606(1974)85 2.0.co;2

1943-2674

Frederick J. Swanson, Hartmut W. Baitis, Jaroslav Lexa, Jack Dymond,

Ocean Acidification Effects and Responses

Research Article| November 01, 1974 Geology of Santiago, Rábida, and Pinzón Islands, Galápagos FREDERICK J. SWANSON; FREDERICK J. SWANSON 1Geology Department, University of Oregon, Eugene, Oregon 97403 Search for other works by this author on: GSW Google Scholar HARTMUT W. BAITIS; HARTMUT W. BAITIS 2Center for Volcanology, University of Oregon, Eugene, Oregon 97403 Search for other works by this author on: GSW Google Scholar JAROSLAV LEXA; JAROSLAV LEXA 2Center for Volcanology, University of Oregon, Eugene, Oregon 97403 Search for other works by this author on: GSW Google Scholar JACK DYMOND JACK DYMOND 3Department of Oceanography, Oregon State University, Corvallis, Oregon 97331 Search for other works by this author on: GSW Google Scholar GSA Bulletin (1974) 85 (11): 1803–1810. https://doi.org/10.1130/0016-7606(1974)85 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 FREDERICK J. SWANSON, HARTMUT W. BAITIS, JAROSLAV LEXA, JACK DYMOND; Geology of Santiago, Rábida, and Pinzón Islands, Galápagos. GSA Bulletin 1974;; 85 (11): 1803–1810. doi: https://doi.org/10.1130/0016-7606(1974)85 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 Santiago, Pinzón, and Rábida Islands are each single volcanoes that lie along a north-trending line near the center of the Galápagos Archipelago. The core volcano of Santiago Island and its flanking lava fields are composed of basaltic to intermediate lava of alkalic parentage. The smaller islands of Rábida and Pinzón are constructed of tholeiitic lava and tuff, ranging in composition from basalt to siliceous trachyte. On each of these two islands, products of eruptive cycles are preserved as tuff-flow sequences of decreasing degree of differentiation and increasing phenocryst abundance up-section, possibly a consequence of tapping successively deeper levels of compositionally zoned magma chambers.Island age generally increases to the south away from the Galápagos rift. Volcanic activity on Santiago spanned most of the past 0.7 m.y. K-Ar ages of rocks exposed on Rábida range from about 1.0 to 0.7 m.y.; those on Pinzón are approximately 1.2 to 0.8 m.y. in age.A part of the tectonic history of the central and southeastern Galápagos Islands is recorded in conspicuous, east-trending alignments of volcanic vents on Santiago and parallel normal faults and some aligned vents on six other islands to the southeast. The central islands among this group are also characterized by uplifted submarine rocks. On the basis of geological and geophysical observations, we hypothesize that this uplift, north-south distention, and associated volcanism may have resulted when an east-trending curtain of mantle upwelled beneath the center of the archipelago during the past 0.5 m.y. The east-trending tectonic pattern appears to be superimposed on the older northwest and northeast trends that have been cited for the entire island group. 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.