| 湖南板溪脉岩的年代学、岩石学、地球化学及其构造环境 |
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| 关键词:Banxi dykes age upper crust underplating |
| 基金项目:国家自然科学基金项目（编号：40472053）；中国科学院创新项目（编号：KZCZ2-102） |
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| Chronology, Petrology, Geochemistry and Tectonic Environment of Banxi Quartz Porphyry Dikes, Hunan Province |
| Felsic or mafic dikes mostly intruded into antimony-gold ore districts in central Hunan, and there are still no clear ideas concerning the relations between these dikes and the ore deposits. The authors revealed that the intrusion of Banxi quartz porphyry dikes took place at 200 Ma±(K-Ar), at least 200 Ma younger than Banxi antimony mineralization. Therefore there are no relations between the dikes and the formation of the ore deposit. Banxi dikes are peraluminous rocks, their A/CNK= 1.08～2.61,A/NK= 1.08～2.71, K_2O=0.9%～3.66%, K_2O+Na_2O=4.28%～7.5%,and K_2O/Na_2O<1 in most samples. They are relatively enriched in LREE, with flat LREE and stepwise HREE patterns, (La/Yb)n=14.47～28.11, (Gd/Yb)n=9.8～14.3, and negative Eu anomalies are obvious. All these data imply that the rocks must have experienced strong fractional crystallization. In the pri- mitive mantle normalized spider diagram, they are relatively enriched in LILE, with negative Ti and P anomalies. ( 87Sr/ 86Sr)_i= 0.6653～0.7149, and the reliable ( 87Sr/ 86Sr)_i of B-3 sample is 0.7149, corresponding to 87Sr/ 86Sr ratios of granite in the upper crust. In the plots of tectonic discrimination, they are projected in IAG/ VAG/Syn-COLG regions. In combination with the conclusions reached by other papers, the authors hold that the Banxi dikes were derived from the upper crust and were predominantly attributed to basaltic underplating at about 200 Ma±during the thermal-stress relaxation after the ending of the tectonically thickening event. |
| ZHAO Jun-hong,PENG Jian-tang,HU Rui-zhong,FU Ya-zhou.2005.Chronology, Petrology, Geochemistry and Tectonic Environment of Banxi Quartz Porphyry Dikes, Hunan Province[J].Acta Geoscientica Sinica,26(6):525-534. |
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