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| 海南晨星安山质火山岩地球化学、年代学特征及其构造意义 | |
| 引用本文： | 陈新跃,王岳军,张玉芝,张菲菲,温淑女.海南晨星安山质火山岩地球化学、年代学特征及其构造意义[J].大地构造与成矿学,2013,37(1):99-108. |
| 作者姓名： | 陈新跃 王岳军 张玉芝 张菲菲 温淑女 |
| 作者单位： | 1. 湖南科技大学地质系,湖南湘潭,411201 2. 中国科学院广州地球化学研究所,广东广州,510640 3. 西北大学地质学系,陕西西安,710069 |
| 基金项目： | 国家自然科学基金(批准号:40902062,408256009);中国科学院重大项目(编号:KZCX1-YW-15-1)联合资助 |
| 摘 要： | 海南晨星地区发育一套变安山质火山岩,呈透镜状或层状夹于晚古生代变沉积地层中。该安山质火山岩SiO2含量为52.87%～65.27%;富Al2O3(15.59%～21.55%),具有较高的稀土元素丰度(ΣREE=166.80×10-6～246.21×10-6),平均204.39×10-6,(La/Yb)N=5.78～7.47,(Gd/Yb)N=1.24～1.58;大离子亲石元素富集、高场强元素Nb-Ta和Ti-P亏损明显,Eu弱负异常(δEu=0.72～0.90);在Nb/Y-(Zr/TiO2)×10-4和La/Yb-Sc/Ni图解上落入安山质大陆岛弧型火山岩区。火山岩样品10HN13B的LA-ICP-MS锆石U-Pb年代学测试表明,该安山质火山岩形成年龄为345±4Ma,表明在早石炭世晚期(～345Ma)在海南中部存在有安山质弧岩浆作用。该年龄的获得表明晨星地区夹持该安山质火山岩的原下二叠统峨查组很可能为一套石炭-二叠纪海相火山-碎屑沉积建造,或需要进一步解体。 |
| 关 键 词： | 安山质火山岩 元素地球化学 锆石LA-ICP-MSU-Pb年代学 海南晨星地区 |
Geochemical and Geochronological Characteristics and its Tectonic Significance of Andesitic Volcanic Rocks in Chenxing Area, Hainan |
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| CHEN Xinyue , WANG Yuejun , ZHANG Yuzhi , ZHANG Feifei , WEN Shunv.Geochemical and Geochronological Characteristics and its Tectonic Significance of Andesitic Volcanic Rocks in Chenxing Area, Hainan[J].Geotectonica et Metallogenia,2013,37(1):99-108. | |
| Authors: | CHEN Xinyue WANG Yuejun ZHANG Yuzhi ZHANG Feifei WEN Shunv |
| Institution: | 1.Department of Geology, Hunan University of Science and Technology, Xiangtan 411201, Hunan, China; 2.Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, Guangdong, China, 3.Department of Geology, Northwest University, Xi′an 710069, Shaanxi, China) |
| Abstract: | 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. |
| Keywords: | andesitic volcanic rocks elemental geochemistry zircon LA-ICP-MS U-Pb dating Chenxing area Hainan Island |
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