Research Article| May 01, 1996 Decompression and high-temperature–low-pressure metamorphism in the exhumed floor of an extensional basin, Alboran Sea, western Mediterranean J. P. Platt; J. P. Platt 1University College London, London WC1E 6BT, England Search for other works by this author on: GSW Google Scholar Leg 161 Shipboard Scientists; Leg 161 Shipboard Scientists Search for other works by this author on: GSW Google Scholar J. I. Soto; J. I. Soto 2Instituto Andaluz de Ciencias de la Tierra, 18002–Granada, Spain Search for other works by this author on: GSW Google Scholar Leg 161 Shipboard Scientists; Leg 161 Shipboard Scientists Search for other works by this author on: GSW Google Scholar M. C. Comas; M. C. Comas 2Instituto Andaluz de Ciencias de la Tierra, 18002–Granada, Spain Search for other works by this author on: GSW Google Scholar Leg 161 Shipboard Scientists Leg 161 Shipboard Scientists Search for other works by this author on: GSW Google Scholar Geology (1996) 24 (5): 447–450. https://doi.org/10.1130/0091-7613(1996)024<0447:DAHTLP>2.3.CO;2 Article history first online: 02 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 J. P. Platt, J. I. Soto, M. C. Comas; Leg 161 Shipboard Scientists, Decompression and high-temperature–low-pressure metamorphism in the exhumed floor of an extensional basin, Alboran Sea, western Mediterranean. Geology 1996;; 24 (5): 447–450. doi: https://doi.org/10.1130/0091-7613(1996)024<0447:DAHTLP>2.3.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 SocietyGeology Search Advanced Search Abstract Leg 161 of the Ocean Drilling Program (ODP) has made a major contribution to our understanding of the origin of the Alboran Basin by demonstrating that it is underlain by rocks of continental origin that have undergone high-temperature metamorphism and melting at exceptionally low pressure after exhumation and decompression. Basement rocks recovered from Site 976 consist of high-grade schist and gneiss derived from aluminous sediments, and minor amounts of marble, granitic dikes, and migmatitic segregations of granitic material. Mineral assemblages and textural relations show that an early assemblage including biotite, garnet, staurolite, plagioclase, and rutile is overprinted by a second assemblage of biotite, sillimanite, plagioclase, potassium feldspar, and ilmenite. Both assemblages are overprinted by andalusite, potassium feldspar, and minor garnet. Migmatitic gneiss contains relict andalusite, overprinted by sillimanite and cordierite coexisting with granitic leucosome. Preliminary pressure-temperature estimates suggest that the metamorphic evolution followed an approximately isothermal decompression path from 7 to 3 kbar at temperatures in the range 580 to 630 °C. After decompression, granitic melts formed at <3 kbar and >670 °C, after andalusite breakdown and within the sillimanite stability field. The cored rocks closely resemble high-grade metamorphic rocks in the adjacent Betic Cordillera of southern Spain, which yield early Miocene radiometric dates. At ODP Site 976 they are overlain by middle Miocene marine sediments. The combination of exhumation in an extensional tectonic environment and the evidence for high and increasing temperature during exhumation provide support for and new constraints on current models for the basin that involve the removal of lithospheric mantle below a zone of continental collision, accompanied or followed by extension. 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.
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Platt et al. (1996) studied this question.