Geochemical and Geochronological Characteristics and Its Tectonic Significance of Andesitic Volcanic Rocks in Chenxing Area, Hainan
详细信息
- 责任者：Chen Xinyue (Department of Geology ; Hunan University of Science and Technology ; Xiangtan 411201 ; China) ; Wang Yuejun
- 刊名：Geotectonica et Metallogenia
- 出版年：2013
- 卷期：37(1)
- 关键词：变火山岩 ; metavolcanic rocks ; 元素地球化学 ; elements geochemistry ; 海南 ; Hainan Province
- 页码：p.99-108
- 图表：illus., 2 tables, 61 refs.
- 分类号：0802
- issnNo：ISSN1001-1552
- isbnNo：CN44-1595/P
摘要
The volcanic rocks in the Chenxing area (Hainan Island), interlayered with Paleozoic siliticlastics, experienced greenschist- and amphibolite-facies metamorphism. These volcanic rocks are andesitic with SiO2 and Al2O3 contents varying in ranges of 51.70%~64.14% and 15.59%~21.55%, respectively. They show high REE abundance (ΣREE=(166.80~246.21)×10-6, with (La/Yb)N of 5.78~7.47, (Gd/Yb)N of 1.24~1.58 and δEu of 0.72~0.90). These rocks are characterized by enrichment in LILE and depletion in HFSE with significant Nb-Ta and P-Ti negative anomalies, showing an affinity to island-arc rocks. 10HN13B samples, representative of the andesite in the Chenxing area, yielded LA-ICP-MS zircon U-Pb ages of 241~2312 Ma with three age-clusters of (546±10) Ma, (431±5) Ma and (345±4) Ma. The age of (345±4) Ma was interpreted to be the crystallization age. Our data show that late Paleozoic sequence in the Chenxing area might be deposited at early Carboniferous period. In combination with other geological observations, it is inferred that early Carboniferous andesitic island possibly occurred along the Banxi-Chenxing area, central Hainan.
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