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引用本文:吴美仁,陈祺,王先广,陈国华,万浩章,严加永,欧阳永棚. 赣东北枣林碧玄岩地球化学特征及成因[J]. 中国地质, 2019, 46(4): 850-860.
WU Meiren,CHEN Qi,WANG Xianguang,CHEN Guohua,WAN Haozhang,YAN Jiayong,OUYANG Yongpeng. Geochemistry and petrogenesis of the Zaolin basanite in the northeastern Jiangxi Province[J]. Geology in China, 2019, 46(4): 850-860(in Chinese with English abstract).
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赣东北枣林碧玄岩地球化学特征及成因
吴美仁1, 陈祺1, 王先广2, 陈国华1, 万浩章1, 严加永3, 欧阳永棚1
1.江西省地质矿产勘查开发局九一二大队, 江西 鹰潭 335001;2.江西省地质勘查基金管理中心, 江西 南昌 330025;3.中国地质科学院深部探测中心, 北京 100037
摘要:
在中国东部赣东北朱溪矿集区枣林地段发现两条新生代碧玄岩岩脉。地球化学研究表明该碧玄岩具有低SiO2(41.08%~42.94%),高Mg#(0.61~0.65),高TiO2(2.19%~2.43%),高Na2O+K2O(4.95%~6.30%)的特点。∑REE为299.16×10-6~375.00×10-6,LREE/HREE比值为5.45~6.71,表明轻稀土富集,δEu为0.88~0.94,具微弱Eu负异常。微量元素特征表现出较高Ni、Cr、Sc含量,蛛网图显示明显富集Nb、Ta、Th、Zr等元素,亏损Ba、Ti、K、P等。主量元素相关图解和不相容元素比值显示岩石在演化过程中未遭受地壳混染。综合分析岩石微量元素数据及相关图解,文章认为由于太平洋板块俯冲,导致软流圈地幔携带碳酸盐熔体上涌与岩石圈地幔相互作用,使得0.2%~0.5%石榴石相二辉橄榄岩与0.5%~1%尖晶石相二辉橄榄岩发生部分熔融,生成碧玄岩原始岩浆。
关键词:  碧玄岩  地球化学特征  岩石成因  朱溪矿集区  枣林地区
DOI:10.12029/gc20190415
分类号:P588.14
基金项目:中国地质调查局项目(121201103000150017、12120113065300、DD20160346、DD20160082、DD20190012)、江西省地质勘查基金管理中心项目(矿[2015]00-13)、国土资源公益性行业科研专项项目(201411035)和江西省地质矿产勘查开发局项目(赣地矿字[2017]78号)联合资助。
Geochemistry and petrogenesis of the Zaolin basanite in the northeastern Jiangxi Province
WU Meiren1, CHEN Qi1, WANG Xianguang2, CHEN Guohua1, WAN Haozhang1, YAN Jiayong3, OUYANG Yongpeng1
1.No. 912 Geological Surveying Party, Jiangxi Bureau of Geology and Mineral Exploration and Development, Yingtan 335001, Jiangxi, China;2.Administration of Geological Exploration of Jiangxi Province, Nanchang 330025, Jiangxi, China;3.China Deep Exploration Center-SinoProbe Center, Chinese Academy of Geological Sciences, Beijing 100037, China
Abstract:
Two Cenozoic basanite dykes were newly discovered in the Zhuxi ore-concentration area, northeastern Jiangxi Province, eastern China. They have high SiO2 (41.08%-42.94%), Na2O+K2O (4.95%-6.30%), TiO2 (2.19%-2.43%) contents, and high Mg# (0.61 -0.65). Geochemistry characteristics of these basanite dykes show they are enriched in Nb, Ta, Th, Zr, Ni, Cr, Sc, while depleted in Ba, Ti, K, and P. Their ∑REE values are from 299.16×10-6 to 375.00×10-6% with LREE/HREE ratios of 5.45-6.71 and δEu values of 0.88 to 0.94. According to the geochemical discrimination diagrams and the ratios of incompatible elements, we suggest that the basanite dykes were derived from partial melting of garnet forsterite (0.2%-0.5%) and herzolite (0.5%-1%), which may be caused by upwelling of carbonate melt in the asthenosphere mantle in response of the subduction of the Paleo-Pacific Ocean.
Key words:  basanite  geochemistry  petrogenesis  Zhuxi ore-concentration area  Zaolin area