Anatexis, Deformation and Exhumation Mechanism for UHP Metamorphic Rocks: A Case Study in the North Qaidam and South Altyn UHP Terrane, Western China
Anatexis, Deformation and Exhumation Mechanism for UHP Metamorphic Rocks: A Case Study in the North Qaidam and South Altyn UHP Terrane, Western China
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DOI：
10.1111/1755-6724.13091
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发表时间：
2017-02
期刊：
影响因子：
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通讯作者：
Sheng‐yao Yu;Jianxin Zhang;San-zhong Li;Yin‐biao Peng;Deyou Sun
中科院分区：
文献类型：
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作者：
Sheng‐yao Yu;Jianxin Zhang;San-zhong Li;Yin‐biao Peng;Deyou Sun
斜长石，(c) 沿晶界的钾长石 + 石英 ± 斜长石 ± 白云母的长英质细脉，以及 (d) 石榴石核中石英 + 长石的多矿物包裹体。混合岩表现为沿晶界的初始微型粒内或液滴状熔体的连续阶段，这些熔体生长成三维互连的粒间网络，然后在压力阴影区域中偏聚和聚集，然后合并形成熔体通道和片体，最终结合形成岩体。锆石U-Pb数据表明，变碱岩和长英质片麻岩的深熔作用发生在430-435Ma期间，即440-450Ma变质峰值之后不久。深熔锆石具有与变质域的 Lu-Hf 同位素特征无法区分，这表明封闭系统没有通过流体从系统外部或在部分熔融过程中从变质前核心添加 Hf。全岩地球化学表明，与变碱岩主体相比，变碱岩内富含斜长石的无色体的 REE 和 HFSE 含量较低，但 LILE（例如 Rb、Ba、K、Sr 和 Pb）含量较高。富含斜长石
plagioclase, (c) felsic veinlets of K-feldspar + quartz ± plagioclase ± muscovite along grain boundaries, and (d) polymineral inclusions of quartz + feldspar in garnet cores. Migmatite shows successive stages of initial miniscale intragranular or droplet-like melt along grain boundaries, which grow into three-dimensional interconnected intergranular network, then segregate and accumulate in pressure shadow areas and then merge to form melt channels and sheets that finally combining forming pluton. Zircon U-Pb data suggested that anatexis of metabasite and felsic gneiss occurred during 430– 435Ma, shortly after peak metamorphism at 440–450Ma. The anatectic zircons have Lu-Hf isotope features that are indistinguishable from those of the metamorphic domains, indicating a closed system with no Hf was added either from outside the system via fluids or from the pre-metamorphic cores during partial melting. Whole-rock geochemistry suggests that the plagioclase-rich leucosomes within metabasite have lower contents of both REE and HFSE but higher LILE (e.g., Rb, Ba, K, Sr, and Pb) than the metabasite hosts. The plagioclase-rich