| 新疆百口泉闪长岩中高An值斜长石的成因及岩石学意义 |
| |
| 引用本文： | 陈博,朱永峰.新疆百口泉闪长岩中高An值斜长石的成因及岩石学意义[J].岩石学报,2015,31(2):479-490. |
| |
| 作者姓名： | 陈博 朱永峰 |
| |
| 作者单位： | 国土资源部岩浆作用成矿与找矿重点实验室, 西安地质矿产研究所, 西安 710054;北京大学地球与空间科学学院, 北京 100871 |
| |
| 基金项目： | 本文受国家自然科学基金项目(41372062、41121062)资助. |
| |
| 摘 要： | 岩浆成因的高An值斜长石(An80~100)是玄武质岩浆早期结晶的产物,由于其形成条件较为苛刻,它对于限定寄主岩浆条件和探讨岩石成因有重要的指示作用。在新疆西准噶尔百口泉地区发育含高An值斜长石(An80~90)的闪长岩,高An值斜长石呈不规则包裹体形式存在于闪长岩主体斜长石中(An40~60)。锆石SHRIMP定年显示百口泉闪长岩形成于316.9±2.9Ma(MSWD=1.5),闪长岩主、微量元素和Sr-Nd同位素与区域内同时期岩浆作用产物具有相似的演化趋势。根据闪长岩岩石学特征,结合高An值斜长石的实验研究成果,本文认为百口泉闪长岩中的高An值斜长石不是捕虏晶,也不是闪长岩的结晶产物,而是与闪长岩成岩过程相关的循环晶。依据角闪石铝压力计的估算,闪长岩结晶于1.2~2.9kbar,与实验条件下获得的高An值斜长石产出的压力范围相符。高An值斜长石的产出表明原始岩浆具有富水、亏损的特征,对于探讨整个岩浆系统的演化过程有重要指示意义。
|
| 关 键 词： | 高An值斜长石 循环晶 闪长岩 岩浆作用 西准噶尔 |
| 收稿时间： | 2014/4/30 0:00:00 |
| 修稿时间： | 2014/7/25 0:00:00 |
The origin of high-An plagioclase in diorite from Baikouquan, Xinjiang and its petrogenetic significance |
| |
| CHEN Bo and ZHU YongFeng.The origin of high-An plagioclase in diorite from Baikouquan, Xinjiang and its petrogenetic significance[J].Acta Petrologica Sinica,2015,31(2):479-490. |
| |
| Authors: | CHEN Bo and ZHU YongFeng |
| |
| Institution: | Key Laboratory for the Study of Focused Magmatism and Giant Ore Deposits, MLR; Xi'an Institute of Geology and Mineral Resources, Xi'an 710054, China;School of Earth and Space Sciences, Peking University, Beijing 100871, China |
| |
| Abstract: | Magmatic high-An plagioclase (An80~100) crystallizes at the early stage of basaltic melt evolution. Due to the restricted conditions under which high-An plagioclase can form and preserve, it can help constrain the crystallization environment and petrogenesis of the host magma. High-An plagioclase (An80~90) bearing diorite outcrops in Baikouquan, West Junggar, Xinjiang. It was dated to be 316.9±2.9Ma (MSWD=1.5) by zircon SHRIMP. The high-An plagioclase occur as irregular patches in the predominant plagioclase of diorite. The major and trace elements and Sr-Nd isotopic data match the trend of the contemporary intrusions in this region. Detailed petrological and mineralogical studies demonstrate the high-An plagioclase are antecryst which belong to the magmatic system producing the host but are not directly a consequence of the crystallization of the host. They came from an earlier pulse of magma and which are incorporated in a later pulse. Based on the Al-in-amphibole geobarometer, the diorite crystallized at 1.2~2.9kbar, which is compatible with the condition for the high-An plagioclase formation. The crystallization of high-An plagioclase in Baikouquan diorite suggests a H2O-rich and depleted primary magma, and has a profound implication on the magmatic system. |
| |
| Keywords: | High-An plagioclase Antecryst Diorite Magmatism West Junggar |
| 本文献已被 CNKI 等数据库收录！ |
| 点击此处可从《岩石学报》浏览原始摘要信息 |
| 点击此处可从《岩石学报》下载免费的PDF全文 |
|
