The tin-granites and their relation to mineralization in Tengchong, Yunnan

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Authors:Mao Jingwen; Zhang Shilu; Rossi, P.
Author Affiliations:Primary:
Chinese Academy of Geological Science, Institute of Mineral Deposits, Beijing, China
Other:
Yunnan Bureau of Geology and Mineral Resources, China
BRGM-CNRS, France
Volume Title:Yanshi Xuebao Acta Petrologica Sinica
Source:Yanshi Xuebao = Acta Petrologica Sinica, 1987(4), p.32-43. Publisher: Science Press, Beijing, China. ISSN: 1000-0569
Publication Date:1987
Note:In Chinese with English summary. 5 refs.; illus., incl. 2 tables, geol. sketch map
Summary:Lai lishan, Guyong and Tieyaostan granite bodies were taken as examples for discussing the inherent relation between tin-barren granite and tin granite in this paper through studying the characteristics of the mineralogy petrology and geochemistry. Based on the work mentioned above the origin, evolution of the granitoids associated with tin deposits and their relation to mineralization were discussed using the methods of isotopic geology. The main conclusions can be summed up as follows: 1. In rock series from granodiorite to monzonitic (syenite) granite mafic minerals decrease with increasing felsic minerals. In the meantime, or in k-feldspar increases and An in plagioclase decreases. The prominent feature k-feldspar and plagioclase in granodiorite is the well developed composition zonation. FM value of biotite increase. The evolutional tendency of its composition is noted with decrease of cesium down and increase of iron and aluminium the species of accessory minerals become diversified and more complex. At the same time Fe2+/Fe3+ ratio of magnetite gradually decreases. 2. Both types of granitoids mentioned above belong to postaluminium granite series with corundum as the standard mineral ranging from 0.1 to 3.67. In the granite series from granodiorite to monzonite (syenite) silica-alkali component increases, while mafic, Al2O3, CaO content decreases. The latter had a evident feature of high differentiation with average index of 90.99, K/Rb = 68-91. However, for the former one the differentiation index is 81.69, K/Rb = 182.3. The evolutional tendency of the REE in the granitoids is that from an early to a late stage the total REE, LREE, δEu value decrease, while the HREE increase either in the granite bodies of different substages of in the rocks with different crystallization time in same granite body. In the rock series from granodiorite to monzonite (syenite) granite the REE evolution is controlled by the crystallization of plagioclase and other rock forming minerals. A group of accessories enriched in LREE affect the redistribution of the REE in the same monzonite (syenite) granite. 4. The results of Sm-Nd, Rb-Sr and O isotopes unanimously show that the compound granites in Tengchong originated from the crust as multi-substage products in the same stage. Gaoligong System were supposed to be their mother source. The origin of tin in the granite was related to the regional geochemistry. The multiple fractionation and evolution of the granitoids played a role in the formation of tin deposits. The collision between the Eurasian Plate and the Indian Plate was the leading factor for the granitic magmatism and the mineralization. [R.A.H.]
Subjects:Endogene processes; Fractional crystallization; Granites; Igneous rocks; Magmas; Magmatism; Metal ores; Mineral deposits, genesis; Mineralization; Plutonic rocks; Tin ores; Asia; China; Far East; Tengchong; Yunnan China
Coordinates:N250200 N250200 E0982800 E0982800
Abstract Numbers:88M/3904
Record ID:1999056786
Copyright Information:GeoRef, Copyright 2019 American Geosciences Institute.
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