Thy, P. et al. (1999): Low-pressure melting studies of basalt and basaltic andesite from the Southeast Greenland continental margin and the origin of dacites at Site 917

Leg/Site/Hole:
ODP 152
ODP 152 917
ODP 152 918
Identifier:
2000-063788
georefid

10.2973/odp.proc.sr.163.114.1999
doi

Creator:
Thy, P.
University of California at Davis, Department of Geology, Davis, CA, United States
author

Lesher, Charles E.
Oregon State University, United States
author

Mayfield, J. D.
Ocean Drilling Program, United States
author

Identification:
Low-pressure melting studies of basalt and basaltic andesite from the Southeast Greenland continental margin and the origin of dacites at Site 917
1999
In: Larsen, Hans-Christian, Duncan, Robert A., Allan, James F., Aita, Yoshiaki, Arndt, Nicholas T., Buecker, Christian J., Cambray, Herve, Cashman, Katharine V., Cerney, Brian P., Clift, Peter D., Fitton, J. Godfrey, Le Gall, Bernard, Hooper, Peter R., Hurst, Stephen D., Krissek, Lawrence A., Kudless, Kristen E., Larsen, Lotte Melchior, Lesher, Charles E., Nakasa, Yukari, Niu, Yaoling, Philipp, Harald, Planke, Sverre, Rehacek, Jakub, Saunders, Andrew D., Teagle, Damon A. H., Tegner, Christian, Scroggs, John (editor), Proceedings of the Ocean Drilling Program; scientific results, Southeast Greenland margin; covering Leg 163 of the cruises of the drilling vessel JOIDES Resolution, Reykjavik, Iceland, to Halifax, Nova Scotia, sites 988-990, 3 September-7 October 1995
Texas A & M University, Ocean Drilling Program, College Station, TX, United States
163
95-112
A series of 1-atm. melting experiments on basaltic flows collected from Holes 918D and 989B in the oceanic succession of the East Greenland continental margin can be used to define possible phase equilibria and liquid lines of descent. A sample from Site 918 (Section 152-918D-108R-2) shows the melting order low-Ca pyroxene (1153 degrees C), augite (1182 degrees C), olivine (1192 degrees C), and plagioclase (1192 degrees C). A sample from Site 989 (Section 163-989B-10R-7) melts in the order of low-Ca pyroxene (1113 degrees C), augite (1167 degrees C), plagioclase (1177 degrees C), and olivine (1184 degrees C). In particular, the relatively early appearance of low-Ca pyroxene distinguishes the melting relations for the oceanic succession from those observed for the basaltic continental succession at Site 917. A basaltic andesite flow from the Middle Series at Site 917 (Section 152-917A-27R-4) shows the melting order of low-Ca pyroxene (1142 degrees C), plagioclase (1173 degrees C), and olivine (1173 degrees C). This melting order is difficult to reconcile with the observed large compositional variations in SiO (sub 2) and FeO for the Middle Series, which imply early magnetite fractionation. Major element considerations and rare-earth element modeling of the dacites of the Middle Series suggest that they formed by low extent of melting (<20%) of continental hydrated gabbroic or mafic amphibolite at pressures <8 kbar. These crustally derived melts represent possible contaminants of basaltic magmas of the Lower and Middle Series at Site 917.
English
Serial
Coverage:Geographic coordinates:
North:63.2930
West:-39.4939East: -38.3820
South:63.0534

Geochemistry of rocks, soils, and sediments; Igneous and metamorphic petrology; andesites; Arctic region; Atlantic Ocean; basalts; Cenozoic; continental margin; dacites; East Greenland; genesis; geochemistry; Greenland; igneous rocks; Leg 152; low pressure; lower Tertiary; magmatism; major elements; melting; metals; mineral composition; North Atlantic; Ocean Drilling Program; ocean floors; ODP Site 917; ODP Site 918; phase equilibria; pressure; rare earths; South Greenland; Tertiary; volcanic rocks;

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