Peridotite-Gabbro Complexes as Keys to Petrology of Mid-Oceanic Ridges

Research Article| August 01, 1969 Peridotite-Gabbro Complexes as Keys to Petrology of Mid-Oceanic Ridges T. P THAYER T. P THAYER U.S. Geological Survey, Washington, D. C. Search for other works by this author on: GSW Google Scholar Author and Article Information T. P THAYER U.S. Geological Survey, Washington, D. C. Publisher: Geological Society of America Received: 02 Dec 1968 Revision Received: 03 Mar 1969 First Online: 02 Mar 2017 Online ISSN: 1943-2674 Print ISSN: 0016-7606 Copyright © 1969, 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 (1969) 80 (8): 1515–1522. https://doi.org/10.1130/0016-7606(1969)80[1515:PCAKTP]2.0.CO;2 Article history Received: 02 Dec 1968 Revision Received: 03 Mar 1969 First Online: 02 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn Email Tools Icon Tools Get Permissions Search Site Citation T. P THAYER; Peridotite-Gabbro Complexes as Keys to Petrology of Mid-Oceanic Ridges. GSA Bulletin 1969;; 80 (8): 1515–1522. doi: https://doi.org/10.1130/0016-7606(1969)80[1515:PCAKTP]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 Two suites of olivine-rich ultramafic and feldspathic rocks appear to be present in the Mid-Atlantic Ridge: one which seems to have alkalic affinities, and one similar to the chromitite-bearing alpine peridotite-gabbro complexes. The similarities of rocks in the two environments— continental and oceanic—imply that much about the petrology of mid-oceanic ridges may be learned from studies of continental complexes, and that silicic rocks have been formed in the mantle. Although gabbros in St. Paul Rocks and similar rocks at Tinaquillo, Venezuela, and Lizard, England, have been interpreted as not comagmatic with intimately associated peridotite by some petrologists, evidence to the contrary at Lizard is discussed. Association of fresh gneissic gabbro, some containing quartz, with talcose serpentinite, amphibole schist, quartz diorite and epidotic but unsheared basalts along the Mid-Atlantic Ridge is believed to indicate presence of alpine-type rocks that occur normally in eugeosynclinal belts.Gabbro, described as partly interlayered with peridotite by gravitational differentiation, forms major parts of three widely separated ultramafic complexes which have been interpreted as slices of oceanic crust and upper mantle: the Troodos massif in Cyprus, the Bowutu Mountains in Papua, and the Camagüey complex in central Cuba. If, as Dietz has suggested, peridotite and related rocks in eugeosynclines represent fragments of ocean rind formed along mid-oceanic ridges and moved laterally by ocean-floor spreading, gabbro must be an essential constituent of the upper mantle. This could account for many geophysical anomalies, but would complicate some postulated mechanisms involved in ocean-floor spreading. 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.