The Shahewan rapakivi-textured granite-quartz monzonite pluton, Qinling orogen, central China: Mineral composition and petrogenetic significance
| Autor: | X. Wang, T. Wang, I. Haapala, X. Lu |
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| Jazyk: | angličtina |
| Rok vydání: | 2002 |
| Předmět: | |
| Zdroj: | Bulletin of the Geological Society of Finland, Vol 74, Iss 1-2, Pp 133-146 (2002) |
| Druh dokumentu: | article |
| ISSN: | 0367-5211 1799-4632 |
| DOI: | 10.17741/bgsf/74.1-2.006 |
| Popis: | The Mesozoic Shahewan pluton consists of four texturally different types of biotite-hornblende quartz monzonite. In the porphyritic types alkali feldspar occurs as euhedral or ovoidal megacrysts that are often mantled by one or more plagioclase shells, and as smaller grains in the groundmass. Quartz, plagioclase (An20–28), biotite, and hornblende occur as inclusions in the alkali feldspar megacrysts and, more abundantly, in the groundmass. Euhedral quartz crystals in the groundmass are not as common and well developed as in typical rapakivi granite. Compared to typical rapakivi granites, the mafic minerals (biotite and hornblende) are rich in Mg and poor in Fe, and the whole rock is low in Si, K, F, Ga, Zr, LREE, Fe/Mg, and K/Na. The rocks of the Shahewan pluton are thus regarded as rapakivi-textured quartz monzonites and granites but not true rapakivi granites. |
| Databáze: | Directory of Open Access Journals |
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