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越南西北部Posen花岗岩锆石U-Pb年龄和Hf同位素组成特征 被引量:5
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作者 HIEU PhamTrung 陈福坤 +4 位作者 祝禧艳 王伟 NGUYEN ThiBichThuy BUI MinhTam NGUYEN QuangLuat 《岩石学报》 SCIE EI CAS CSCD 北大核心 2009年第12期3141-3152,共12页
本文报道出露于越南西北部的Posen花岗岩岩体锆石U-Pb年龄和Hf同位素组成特征,讨论岩石成因和该地区新元古代岩浆作用的大地构造意义。分析3个花岗岩样品获得723Ma至760Ma的锆石U-Pb年龄,表明花岗岩形成于新元古代。该花岗岩的锆石Hf同... 本文报道出露于越南西北部的Posen花岗岩岩体锆石U-Pb年龄和Hf同位素组成特征,讨论岩石成因和该地区新元古代岩浆作用的大地构造意义。分析3个花岗岩样品获得723Ma至760Ma的锆石U-Pb年龄,表明花岗岩形成于新元古代。该花岗岩的锆石Hf同位素组成有较大的变化范围,ε_(Hf)(t)值变化范围为-16.1至+3.4,单阶段Hf模式年龄为1186~1945Ma,暗示Posen花岗岩有着复杂的源区物源组成。在误差范围内,锆石两阶段Hf同位素模式年龄值主要集中在2.0~2.1Ga,与两阶段Nd同位素模式年龄值2.1~2.2Ga一致,说明花岗岩体主要由古元古代地壳物质部分熔融形成的。部分锆石颗粒具有正ε_(Hf)(t)值,可能指示花岗岩岩浆形成过程中存在壳-幔混合相互作用。在越南西北部发育新元古代岩浆作用可能与扬子板块广泛发育的、伴随Rodinia超大陆裂解过程的岩浆活动存在成因的联系,也揭示越南西北部地体可能与扬子板块具有亲缘关系,因此,可以推断马江断裂带应该代表印支板块和华南板块之间的古特提斯缝合带在越南西北部的延伸。 展开更多
关键词 越南 西北部 花岗 岩体锆石 U-PB年龄 同位素组成 组成特征 isotopic composition ages Yangtze block 新元古代 模式年龄 扬子板块 浆作用 material sources RODINIA超大陆 两阶段 South China study fault zone
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Zircon geochemistry of different intrusive phases of Weiya pluton: implications for magma genesis 被引量:3
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作者 张遵忠 顾连兴 +3 位作者 吴昌志 吴华 郗爱华 唐俊华 《Journal of Central South University of Technology》 EI 2005年第4期472-477,共6页
The characteristics of hosted magmas and their petrogenesis based on electron microprobe determination of trace element contents in zircons were discussed. Trace element geochemistry of zircons indicates that zircons ... The characteristics of hosted magmas and their petrogenesis based on electron microprobe determination of trace element contents in zircons were discussed. Trace element geochemistry of zircons indicates that zircons in both gabbro and quartz syenite have two-generations. Zircons of the first generations are crystallized in the magma chamber, whereas those of the second generations are formed in supercooling environment. The former is richer in Zr, but poorer in U, Th, Hf and Y. Quartz diorite porphyrite contains zircons that can be distinguished into the early and late generations. Compared to the late generation, the early generation is richer in Zr but poorer in U, Th, Hf and Y. No conspicuous disruption of zircon evolution has been found in both biotite monzogranite and fine-grained granite. However, the content of zircon in fine-grained granite is higher in U, Th and Y and lower in Zr relative to biotite monzogranite without significant contrast in mass fraction ratio of ZrO2 to HfO2 ratio. Such differences in zircon geochemistry of various intrusive phases and the occurrence of the two zircon generations within a single intrusive phase suggest that these phases of magmas are generated from diverse sources during post-collisional continental extension. These magmas ascend rapidly and cool quickly in a short interval. 展开更多
关键词 ZIRCON trace element PETROGENESIS Weiya Eastern Tianshan
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Early Cretaceous uplift history of the Dabie orogenic belt: Evidence from pluton emplacement depths 被引量:8
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作者 WANG YongSheng WANG HaiFeng +1 位作者 SHENG Yong XIANG BiWei 《Science China Earth Sciences》 SCIE EI CAS 2014年第5期1129-1140,共12页
The North Dabie complex unit (NDC) is a widely exposed petro-tectonic unit. To understand post-orogenic uplift history and mechanism of the Dabie orogenic belt, many samples of granite, granodiorite, diorite, and al... The North Dabie complex unit (NDC) is a widely exposed petro-tectonic unit. To understand post-orogenic uplift history and mechanism of the Dabie orogenic belt, many samples of granite, granodiorite, diorite, and alkali feldspar granite with precise zircon U-Pb ages were collected for electron microprobe analysis of hornblende. Emplacement pressure values were then cal- culated by using an Al-in-hornblende geobarometer. The result shows that total A1 (A1T) values in hornblende range from 1.17 to 1.97 p.f.u., XFe(=Fe/(Fe+Mg)) from 0.4 to 0.65, and corresponding pressure values from 256.8 to 676.2 MPa for A1T greater than 1.17. It is suggested that although the main mechanism for the uplift is tectonic extension, inhomogeneous uplift related to the pluton emplacement is also important during post-orogenic evolution of the Dabie orogenic belt. Emplacement depth dis- tribution of the plutons shows that uplift in the NDC is affected by horst-graben structures since 120 Ma. 展开更多
关键词 Dabie orogenic belt North Dabie complex belt Early Cretaceous plutons Al-in-hornblende geobarometer
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