| 西天山加满特一带早二叠世乌郎组双峰式火山岩锆石U-Pb年代学及Hf同位素组成 |
| |
| 引用本文： | 陈邦学,徐胜利,周能武,白权金,黄基汉,郑勇.西天山加满特一带早二叠世乌郎组双峰式火山岩锆石U-Pb年代学及Hf同位素组成[J].高校地质学报,2019,25(3):364. |
| |
| 作者姓名： | 陈邦学 徐胜利 周能武 白权金 黄基汉 郑勇 |
| |
| 摘 要： | 西天山加满特一带基性与酸性火山岩在时空上紧密伴生，其SiO2含量分别为41.89%~52.75%和74.79%~78.51%，具
有明显的Daly间断，属于典型的双峰式火山岩组合，其中的基性单元属于碱性系列，酸性单元属于钙碱性系列。对流纹岩
进行LA-ICP-MS锆石U-Pb法测年和Hf同位素分析，获得其形成年龄为（294.2±0.8） Ma，属于早二叠世，其εHf(t)为较高的
正值（8.0~17.1），二阶段Hf模式年龄TDM2(Hf)平均值为468 Ma。通过对加满特一带双峰式火山岩的地球化学特征和成因类
型进行探讨，表明其不属于同源岩浆演化成因，其中玄武岩是富集石榴石地幔源区发生了尖晶石相橄榄岩向石榴石相橄榄
岩过渡相部分熔融的产物，流纹岩是亏损地幔源底侵新生地壳部分熔融的产物，二者形成于板内伸展环境。结合区域构造
演化，认为西天山在早二叠世已经进入伸展构造背景。
|
| 关 键 词： | 西天山 双峰式火山岩 流纹岩 玄武岩 |
Zircon U-Pb Chronology and Hf Isotopic Compositions of the Early Permian Bimodal Volcanic Rocks from Wulang Formation in Jiamante Area of Western Tianshan，Xinjiang |
| |
| CHENBangxue,XU Shengli,ZHOUNengwu,BAI Quanjin,HUANGJihan,ZHENG Yong.Zircon U-Pb Chronology and Hf Isotopic Compositions of the Early Permian Bimodal Volcanic Rocks from Wulang Formation in Jiamante Area of Western Tianshan，Xinjiang[J].Geological Journal of China Universities,2019,25(3):364. |
| |
| Authors: | CHENBangxue XU Shengli ZHOUNengwu BAI Quanjin HUANGJihan ZHENG Yong |
| |
| Abstract: | The basic and acidic volcanic rocks with SiO2 contents of 41.89%-52.75% and 74.79%-78.51%, respectively, are closely
associated in time and space in the area of Jiamante, western Tianshan Mountains. These volcanic rock associations show distinct
“Daly gap”, thus can be ascribed to the typical bimodal volcanic assemblage. The basic units can be grouped into alkaline series,
whereas the acidic units are calc-alkaline series. LA-ICP-MS zircon U-Pb dating and Hf isotopic analysis for rhyolites show that their
formation age is (294.2±0.8) Ma, indicating that they were formed in Early Permian. The volcanic rocks have positive εHf(t) values (8.0-
17.1), and young two-stage model ages with an average of 468 Ma. By integration of the geochemical characteristics and genetic types, it
is shown that the bimodal volcanic rocks in the Jiamante area can not be produced by differentiation from the same magma chamber.
Rather, they were likely originated from different sources. Among them, the basalt was originated from partial melting of the enriched
garnet peridotite induced by the phase transition from spinel peridotite to garnet peridotite, and rhyolite is generated by partial melting
of juvenile crust resulted from underplating of depleted mantle. Both the basic and acidic volcanic rocks were formed in an intraplate
extension environment. In combination with analysis of the regional tectonic evolution, it is suggested that the western Tianshan
Mountains were entered an extensional tectonic setting since the Early Permian. |
| |
| Keywords: | western Tianshan Mountains bimodal volcanic rocks rhyolite basalt |
| 本文献已被 CNKI 等数据库收录！ |
| 点击此处可从《高校地质学报》浏览原始摘要信息 |
|
点击此处可从《高校地质学报》下载全文 |
|
