Title: Granitic to ultramafic rock complexes of the Indian Ocean ridge system, western Indian Ocean
Abstract: Research Article| November 01, 1975 Granitic to ultramafic rock complexes of the Indian Ocean ridge system, western Indian Ocean CELESTE G. ENGEL; CELESTE G. ENGEL 1Scripps Institution of Oceanography, University of California, San Diego, La Jolla, California 92037 Search for other works by this author on: GSW Google Scholar ROBERT L. FISHER ROBERT L. FISHER 1Scripps Institution of Oceanography, University of California, San Diego, La Jolla, California 92037 Search for other works by this author on: GSW Google Scholar Author and Article Information CELESTE G. ENGEL 1Scripps Institution of Oceanography, University of California, San Diego, La Jolla, California 92037 ROBERT L. FISHER 1Scripps Institution of Oceanography, University of California, San Diego, La Jolla, California 92037 Publisher: Geological Society of America First Online: 01 Jun 2017 Online ISSN: 1943-2674 Print ISSN: 0016-7606 Geological Society of America GSA Bulletin (1975) 86 (11): 1553–1578. https://doi.org/10.1130/0016-7606(1975)86<1553:GTURCO>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 CELESTE G. ENGEL, ROBERT L. FISHER; Granitic to ultramafic rock complexes of the Indian Ocean ridge system, western Indian Ocean. GSA Bulletin 1975;; 86 (11): 1553–1578. doi: https://doi.org/10.1130/0016-7606(1975)86<1553:GTURCO>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 During five expeditions of the Scripps Institution of Oceanography to the western Indian Ocean, more than 4,500,000 sq km of the Central Indian Ridge and its branching Southeast Indian Ridge and Southwest Indian Ridge were explored by bathymetric, magnetic, and seismic-reflection profiling. In some 2,800,000 sq km of this region, igneous rocks of the crust, lower crust, and possible upper mantle are exposed by faulting or volcanism. Fifty-six dredge hauls of these igneous rocks were obtained, largely from the major cross-fractures (transform faults) or clefts trending athwart the volcanically active ridges. From north to south, the cross-fractures most intensively sampled were the Vema Fracture Zone, which crosses the crestal area near 9°S, Argo Fracture Zone near 13°30′S, Marie Celeste Fracture Zone near 17°30′S, and the newly delineated "Melville Fracture Zone" trending north-south for more than 600 km near 60°30′E on the Southwest Indian Ridge.Our field and laboratory studies indicate that under a capping of young flow basalt, there is a regional complex of igneous rocks produced by magma generated under the ridges, trapped and differentiated into sill-like, podiform, and larger, crudely stratified to well-stratified sheets. Rocks from the stratiform masses include abundant Iherzolite and minor harzburgite, orthopyroxenite, olivine- and two-pyroxene gabbros, Ti-ferrogabbros, norite, and anorthosite. Some associated diabase intrusions are granophyric and are cut by late-stage dikelets of quartz monzonite and Na-rich trondhjemite. Both calc-alkaline and alkalic lines of differentiation are indicated. The granitic dikelets contain clear, doubly-terminated crystals of zircon, unusual in a terrane of large-cation–depleted rocks.The overlying basalt flows are pillowed with chemical and mineralogical characteristics typical of olivine-bearing tholeiite from the ridge-rise systems of the world oceans.The ubiquitous nature of the crustal complex found throughout the western Indian Ocean, together with data from the Atlantic and Pacific Oceans, suggest that similar rock complexes, dominated in their lower parts by stratiform bodies, are characteristic of most of the igneous crust throughout the world oceans. 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.
Publication Year: 1975
Publication Date: 1975-01-01
Language: en
Type: article
Indexed In: ['crossref']
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Cited By Count: 199
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