| 川西北塔公石英闪长岩地球化学特征和岩石成因 |
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| 引用本文： | 赖绍聪,赵少伟. 川西北塔公石英闪长岩地球化学特征和岩石成因[J]. 延边大学学报(自然科学版), 2015, 0(3): 1-13 |
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| 作者姓名： | 赖绍聪 赵少伟 |
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| 作者单位： | 1. 西北大学 大陆动力学国家重点实验室，陕西 西安 710069； 2. 西北大学 地质学系，陕西 西安 710069 |
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| 摘 要： | 川西北塔公地区位于青藏高原东部，属于松潘—甘孜造山带的东南部边缘。塔公石英闪长岩侵位于晚三叠世地层中，岩体的K-Ar同位素年龄为134～136 Ma，形成于早白垩世。岩石SiO2质量分数为61.37%～62.25%，铝饱和指数为0.93～0.95，全碱质量分数为5.46%～5.77%，里特曼指数为1.62～1.74，样品属于亚碱性准铝质高钾钙碱系列石英闪长岩。岩石Mg#值较高，总体具有高Sr含量、低Nd含量的同位素地球化学特征。N（87Sr）/N（86Sr）值为0.712 589～0.713 009，初始N（87Sr）/N（86Sr）值为0.709 503～0.709 878，N（143Nd）/N（144Nd）值为0.512 135～0.512 196，εNd(t)值均为负（-8.6～-7.5），Nd模式年龄为1.33～1.41 Ga，Hf模式年龄为1.13～1.37 Ga。该岩体是早白垩世期间，川西北地区陆缘-陆内造山环境下由松潘—甘孜造山带古老的下地壳镁铁质物质局部熔融形成的晚碰撞-碰撞后非分异Ⅰ型花岗岩类。
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| 关 键 词： | 石英闪长岩 早白垩世 地球化学 岩石成因 花岗岩 下地壳局部熔融 松潘—甘孜造山带 川西北 |
Geochemistry and Petrogenesis of Quartz Diorite in Tagong Area of Northwest Sichuan |
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| LAI Shao-cong,ZHAO Shao-wei. Geochemistry and Petrogenesis of Quartz Diorite in Tagong Area of Northwest Sichuan[J]. Journal of Yanbian University (Natural Science), 2015, 0(3): 1-13 |
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| Authors: | LAI Shao-cong ZHAO Shao-wei |
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| Affiliation: | 1. State Key Laboratory of Continental Dynamics, Northwest University, Xi’an 710069, Shaanxi, China; 2. Department of Geology, Northwest University, Xi’an 710069, Shaanxi, China |
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| Abstract: | Tagong area of Northwest Sichuan is located in the east of Qinghai-Tibet Plateau, and belongs to the southeast margin of Songpan-Ganzi orogenic belt. The quartz diorites in Tagong area form in Early Cretaceous with K-Ar isotopic ages of 134-136 Ma, and emplace into Late Triassic strata. Mass fractions of SiO2 are 61.37%-62.25%, A/CNK values are 0.93-0.95, mass fractions of total alkali are 5.46%-5.77%, Rittmann indexes are 1.62-1.74, so that the samples belong to subalkaline metaperaluminous high-K calc-alkaline series quartz diorites. The rocks have relative high Mg# values with the isotopic geochemical characteristics of high contents of Sr and low contents of Nd. N(87Sr)/N(86Sr) is 0.712 589-0.713 009 with the initial N(87Sr)/N(86Sr) of 0.709 503-0.709 878, N(143Nd)/N(144Nd) is 0.512 135-0.512 196 with negative εNd(t) of -8.6--7.5; Nd and Hf model ages are 1.33-1.41 Ga and 1.13-1.37 Ga, respectively. The quartz diorites belong to undifferentiation Ⅰ-type granitoids with late- to post-collision caused by partial melting of ancient lower crust mafic materials at the continental margin-intercontinental orogenic setting in Northwest Sichuan. |
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| Keywords: | quartz diorite Early Cretaceous geochemistry petrogenesis granite partial melting of lower crust Songpan-Ganzi orogenic belt Northwest Sichuan |
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