Sulfide and oxide minerals from S-type and I-type granitic rocks

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doi: 10.1016/0016-7037(87)90064-0
Authors:Murata, Mamoru; Itaya, Tetsumaru
Author Affiliations:Primary:
Rigaku Ind. Corp., Osaka, Japan
Other:
Okayama Univ. Sci., Japan
Volume Title:Mineralogy and geochemistry of granites and pegmatites
Volume Authors:Papike, J. J., editor
Source:Geochimica et Cosmochimica Acta, 51(3), p.497-507; International Mineralogical Association, 14th general meeting ; symposium on Mineralogy and geochemistry of granites and pegmatites, Stanford, CA, July 13-18, 1986, edited by J. J. Papike. Publisher: Pergamon, Oxford, International. ISSN: 0016-7037
Publication Date:1987
Note:In English. 68 refs.; illus. incl. 4 tables, geol. sketch map
Summary:The mineralogy and principal chemical characteristics of the Ohmine I-type and S-type granitic rocks of Miocene age, Kii peninsula, central Japan, are summarized. The S-type contain higher SiO2 with higher normative Q + ab + or, and Al2O3/(CaO + Na2O + K2O) ratios, lower Sr, and higher 87Sr/86Sr and 18O/16O ratios, compared to the I-type granites. Accessory ilmenite, rutile, pyrrhotite, pyrite and chalcopyrite are common, and their parageneses were determined by modes of occurrence as inclusions within the rock-forming minerals. Parageneses changed with cooling of the granites, with subsolidus reactions for the sulphides occurring in groundmass and inclusions until the T fell to <300°C. S and Cu were lost through the silicates, but removal of Ni through the silicates and along grain boundaries was restricted (the distribution frequency of Ni-pyrrhotite is higher in inclusions than in the groundmass, and higher in I-type enclaves than in host I-type rocks). Ni- pyrrhotite is common in I-type granites, but rare in S-type rocks, sedimentary enclaves, restites and country rocks. This eliminates the possibility that the S-type rocks formed through interaction of I-type magma and sedimentary rocks, or by mixing of I-type and ideal S-type magmas, but were derived from partial melting of intermediate igneous rocks containing hornblende and plagioclase. S-type granites were formed from partial melting of sedimentary rocks containing biotite and orthoclase. [R.K.H.]
Subjects:Cenozoic; Genesis; Geochemistry; Granites; Igneous rocks; Magmas; Mineral composition; Miocene; Neogene; Oxides; Petrology; Phase equilibria; Plutonic rocks; Sulfides; Tertiary; Asia; Far East; Honshu; Japan; I-type granite; Ohmine District; S-type granite
Coordinates:N335500 N341000 E1361000 E1355000
Abstract Numbers:87M/6239
Record ID:1987053727
Copyright Information:GeoRef, Copyright 2019 American Geosciences Institute. Reference includes data from Mineralogical Abstracts, United Kingdom, Twickenham, United Kingdom
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