Platt, J. P. et al. (1996): Decompression and high-temperature-low-pressure metamorphism in the exhumed floor of an extensional basin, Alboran Sea, western Mediterranean
Leg/Site/Hole:
Related Expeditions:
ODP 161
Identifier:
ID:
1996-042322
Type:
georefid
ID:
10.1130/0091-7613(1996)024<0447:DAHTLP>2.3.CO;2
Type:
doi
Creator:
Name:
Platt, J. P.
Affiliation:
University College London, London, United Kingdom
Role:
author
Name:
Soto, J. I.
Affiliation:
Instituto Andaluz de Ciencias de la Tierra, Granada, Spain
Role:
author
Name:
Comas, M. C.
Affiliation:
GEOMAR, Federal Republic of Germany
Role:
author
Name:
Zahn, R.
Affiliation:
Texas A&M University, United States
Role:
author
Name:
Klaus, A.
Affiliation:
Universite de Cergy Pontoise, France
Role:
author
Name:
Aubourg, C.
Affiliation:
ETH-Zurich, Switzerland
Role:
author
Name:
Bernasconi, S.
Affiliation:
Hancock Field Station, United States
Role:
author
Name:
Belanger, P.
Affiliation:
University of Tulsa, United States
Role:
author
Name:
Cornell, W.
Affiliation:
Florida State University, United States
Role:
author
Name:
de Kaenel, E.
Affiliation:
Institut Mediterraneen de Technologie, France
Role:
author
Name:
de Larouziere, F.
Affiliation:
Christian-Albrechts University, Federal Republic of Germany
Role:
author
Name:
Doose, H.
Affiliation:
Tokyo Metropolitan University, Japan
Role:
author
Name:
Fukusawa, H.
Affiliation:
University of Utah, United States
Role:
author
Name:
Hobart, M.
Affiliation:
Parma University, Italy
Role:
author
Name:
Iaccarino, S.
Affiliation:
University of Texas at El Paso, United States
Role:
author
Name:
Ippach, P.
Affiliation:
University of Michigan, United States
Role:
author
Name:
Marsaglia, K.
Affiliation:
INTECHMER, France
Role:
author
Name:
Meyers, P.
Affiliation:
University of Wales, United Kingdom
Role:
author
Name:
Murat, A.
Affiliation:
University of Hawaii, United States
Role:
author
Name:
O'Sullivan, G.
Affiliation:
Vanderbilt University, United States
Role:
author
Name:
Prassad, M.
Affiliation:
University of Technology, Sydney, Australia
Role:
author
Name:
Siesser, W.
Affiliation:
Louisiana State University, United States
Role:
author
Name:
Skilbeck, C. G.
Affiliation:
Kyoto University, Japan
Role:
author
Name:
Tandon, K.
Affiliation:
Role:
author
Name:
Torii, M.
Affiliation:
Role:
author
Name:
Tribble, J.
Affiliation:
Role:
author
Name:
Wilkens, R.
Affiliation:
Role:
author
Identification:
Title:
Decompression and high-temperature-low-pressure metamorphism in the exhumed floor of an extensional basin, Alboran Sea, western Mediterranean
Year:
1996
Source:
Geology (Boulder)
Publisher:
Geological Society of America (GSA), Boulder, CO, United States
Volume:
24
Issue:
5
Pages:
447-450
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 degrees C. After decompression, granitic melts formed at <3 kbar and >670 degrees 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.
Language:
English
Genre:
Serial
Rights:
URL:
Coverage: Geographic coordinates: North:36.2000 West:-5.0000 East:
-4.0000 South:36.1000
Keywords: Igneous and metamorphic petrology; Solid-earth geophysics; Oceanography; Alboran Sea; basement; basins; bathymetry; cores; crust; crustal thinning; decompression; dikes; exhumation; extension tectonics; geologic barometry; geologic thermometry; geophysical methods; geophysical surveys; gneisses; granites; high temperature; high-grade metamorphism; igneous rocks; intrusions; Leg 161; low pressure; Mediterranean Sea; metamorphic rocks; metamorphism; migmatites; mineral assemblages; Ocean Drilling Program; ocean floors; ODP Site 976; P-T conditions; plutonic rocks; pressure; schists; seismic methods; surveys; tectonics; temperature; West Mediterranean;
.