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Geochronology Constraints on the Petrogenesis of Gneissic Alkali‐granite in the Dabie‐Sulu Ultra‐high Pressure Metamorphic Terrain, Donghai County, Eastern China
Author(s) -
XIA Bin,
WANG Min,
ZHANG Yuquan
Publication year - 2014
Publication title -
acta geologica sinica ‐ english edition
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.444
H-Index - 61
eISSN - 1755-6724
pISSN - 1000-9515
DOI - 10.1111/1755-6724.12378_28
Subject(s) - chinese academy of sciences , petrogenesis , china , geochemistry , geology , library science , archaeology , geography , mantle (geology) , computer science
Alkali granite is well known not only for the generation at great depth in the extensional regime (Petro et al., 1979), but also for the association with abundant metallic resources including rare earth element (Yuan zhongxin, 1997), Cu, Mo, Pb, Au and Ag (Tan renli et al., 1995; Zhang yuquan,1997), and so forth. Alkali granite is at times referred to as the protolith of alkali-granitic gneiss in ancient and present orogens, for both appear similar or identical in geochemistry and rock-forming minerals. Some of such gneiss displays a wide spread of U-Pb ages in zircons that may or may not be homogeneously distributed at outcrop (Zhang yuquan et al., 2004; Xiabin et al., 2008). This evidence makes us believe that this alkali-granitic gneiss should have been generated in the solidus state by high-grade metamorphism from sedimentary rocks, in no relation to magmatism. The Dabie-Sulu ultrahigh pressure metamorphic (UHPM) terrain in eastern China provides an excellent example of alkali-granitic gneiss (Fig.1), upon which this study is based. Alkali-granitic gneiss constitutes about half volume of the UHP metamorphic terrain (Chen daogong et al., 2000). It is regarded as garnet-bearing granite or Atype granite that intruded in the late of Protorozoic, and suffered from UHP metamorphism during the collision between the North China and South China plates in early Mesozoic (Zhong zenqiu et al., 1999; Zhang hongfei et al., 2001; Suo shutian et al.,2005). Despite the similarity in geochemistry and mineralogy (Xu shutong et al., 1998), it has an exceptionally larger volume than any alkaline granite in other orogens. This communication focuses on the geochronology and petrologyof alkali-granitic gneiss from Tuofeng and Niushan in Donghai county, Jiangsu province, eastern China (Fig.1), where the UHPM rocks are well preserved. The study work support that the protolith of alkali granite genesis is sedimentary and, the age of the protolith is not earlier than the Paleozoic.