东准噶尔琼河坝岛弧早古生代岩浆活动的锆石U-Pb年龄和Hf同位素证据

张永; 梁广林; 屈迅; 杜世俊; 吴琪; 张征峰; 董连慧; 徐兴旺

东准噶尔琼河坝岛弧早古生代岩浆活动的锆石U-Pb年龄和Hf同位素证据

- 1.
  中国科学院矿产资源研究重点实验室,中国科学院地质与地球物理研究所,北京 100029；中国科学院研究生院,北京 100049
- 2.
  新疆维吾尔自治区地质矿产勘查开发局,乌鲁木齐 830000
- 3.
  中国科学院矿产资源研究重点实验室,中国科学院地质与地球物理研究所,北京 100029
- 4.
  中国科学院矿产资源研究重点实验室,中国科学院地质与地球物理研究所,北京 100029；新疆维吾尔自治区地质矿产勘查开发局,乌鲁木齐 830000
基金项目:
中国科学院知识创新工程主要方向项目（KZCX2-YW-107）、“十一五”国家科技支撑计划重点项目（2006BAB07B01-03）与中国科学院矿产资源重点实验室基金

收稿日期: 2010-05-01

修回日期: 2010-07-15

刊出日期: 2010-08-31

Evidence of U-Pb age and Hf isotope of zircons for Early Paleozoic magmatism in the Qiongheba arc, East Junggar

- 1.
  Key Laboratory of Mineral Resources, Institute of Geology and Geophysics, CAS, Beijing 100029, China; Graduate School of Chinese Academy of Sciences, Beijing 100049, China
- 2.
  Xinjiang Bureau of Geology and Mineral Resources, Uramqi 830000, China
- 3.
  Key Laboratory of Mineral Resources, Institute of Geology and Geophysics, CAS, Beijing 100029, China
- 4.
  Key Laboratory of Mineral Resources, Institute of Geology and Geophysics, CAS, Beijing 100029, China; Xinjiang Bureau of Geology and Mineral Resources, Uramqi 830000, China

Received Date: 01 May 2010

Revised Date: 15 July 2010

Publish Date: 31 August 2010

摘要

摘要: 东准噶尔琼河坝桑德乌兰斑岩铜钼矿区含矿花岗斑岩透长石、石英斑晶粒内破裂构造发育，锆石普遍发育具核内破裂构造或碎裂状的核。破碎的锆石核与透长石、石英斑晶可能形成于深部岩浆房。锆石U-Pb定年结果显示，破碎变形的锆石核年龄为442.2±3.5Ma，锆石环带的年龄为412.7±3.3Ma，前者代表破碎变形锆石的形成时间，后者代表斑岩侵位与结晶的时间。Hf同位素结果显示，破碎的有核锆石与其外环带具一致的εHf(t)初始值与tDM2模式年龄，它们可能为同一岩浆或成因相同的岩浆不同阶段结晶的产物。这意味着琼河坝地区在早古生代(至少在442Ma)就开始有弧岩浆活动。幔源特征的εHf(t)值（10.3~15.1）与较老的模式年龄(tDM2=469~761Ma)显示形成研究区花岗斑岩的岩浆可能源于晚元古代-奥陶纪玄武质地壳的部分熔融。
- 花岗斑岩 /
- 锆石CAMECA /
- U-Pb年龄 /
- Hf同位素 /
- 琼河坝岛弧 /
- 东准噶尔
Abstract: Granite porphyry in the Sangdewulan copper-molybdenum district in the Qiongheba area, East Junggar was characterized by the abundance of sanidine and quartz phenocrysts with intragranular fractures and fractured core zircons, which was formed in a pre-emplacement magma chamber. Zircon U-Pb dating results suggest that the fractured zircons formed at age of about 442.2±3.5Ma, and the rim zircons at about 412.7±3.3Ma. The age of about 413Ma shows the time of emplacement and crystallization of the granite porphyry. Hf isotopic data of zircons suggest that the fractured cores and rim had a similar value of εHf and tDM2, and were most possibly derived from a same magma resources. This indicates that magmatic activity in the Qiongheba arc appeared at least from 442Ma in the Early-Paleozoic era. High εHf(t) value (10.3 ~15.1) and relative big model ages (tDM2=469~761Ma) suggest that magma formed granite porphyry in the Sangdewulan district were likely derived from the remelting of Late-Proterozoic-Ordovician basaltic crust.
- Granite porphyry /
- Zircon CAMECA U-Pb dating /
- Hf isotope /
- Qiongheba arc /
- East Junggar /

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东准噶尔琼河坝岛弧早古生代岩浆活动的锆石U-Pb年龄和Hf同位素证据

Evidence of U-Pb age and Hf isotope of zircons for Early Paleozoic magmatism in the Qiongheba arc, East Junggar

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