Granitoids and coeval mafic microgranular enclaves (MMEs) provide important insights into petrogenesis and crustal evolution. In the eastern sector of the East Kunlun Orogen, the Halazha (HLZ) pluton contains abundant MMEs, recording magma mingling processes. The HLZ pluton comprises quartz diorites and granodiorites, whereas the MMEs have a gabbroic-dioritic composition. This paper provides a detailed description of the petrography and mineralogy of the HLZ pluton and MMEs, and presents new ages and geochemical data. The zircon U–Pb dating results indicate that quartz diorites and granodiorites are ranging from 243 ± 2 Ma to 244.8 ± 1.3 Ma and from 233.3 ± 1.1 Ma to 233.6 ± 1.5 Ma, respectively. The zircon ages of the coeval MMEs are identical to the host rocks, i.e., 244.5 ± 1.1 Ma − 244.5 ± 1.2 Ma, and 233.7 ± 1.3 Ma, respectively. Both quartz diorites and granodiorites contain hornblende, display metaluminous characteristics with average A/CNK values of 0.93 and 0.99, respectively, and thus belong to I-type granite. Both of them are enriched in large-ion lithophile elements such as Rb and Ba and depleted in high-field-strength elements such as Nb and Ta. In addition, they both have low ε() values, ranging from −5.6 to −1.7 and −5.4 to −1.79, respectively. Results suggest that HLZ pluton is derived from magmas formed by the partially melting juvenile mafic lower crust. Quartz diorites experienced hornblende accumulation for its low SiO contents. Whereas, the high Sr/Y ratio of granodiorites attributes to the fractional crystallization of apatite. Notably, the crystallization pressure and temperature (average 3.43 kbar and 764 °C) of the hornblende xenocrysts in MMEs is close to it of the hornblende phenocryst in quartz diorite (average 3.68 kbar and 766 °C). This similarity indicates that MMEs in the quartz diorites resulted from magmatic mingling between the mafic magma and the host rock within the deep crust. The hornblende xenocrysts present in MMEs of the granodiorites contain a higher number of inclusions, reveal higher crystallization pressures (average 2.73 kbar) and temperatures (average 825 °C) compared to their host rocks (average 1.35 kbar and 702 °C). These results suggest that MMEs in granodiorites underwent two distinct magmatic mixing processes: the magmatic mixing of mafic magma in the deep crust and then during the upwelling process after this mixed mafic magma entered the granodiorites.

中文翻译：

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青藏高原北部东昆仑造山带花岗岩类和同时期镁铁质微粒包体的成因：岩相学、U-Pb年代学、地球化学和同位素分析的见解

花岗岩和同时代的镁铁质微颗粒包体（MME）为岩石成因和地壳演化提供了重要的见解。在东昆仑造山带东段，哈拉扎（HLZ）岩体含有丰富的MME，记录了岩浆混合过程。 HLZ 岩体由石英闪长岩和花岗闪长岩组成，而 MME 则具有辉长岩-闪长岩成分。本文详细描述了 HLZ 岩体和 MME 的岩相学和矿物学，并提供了新的年龄和地球化学数据。锆石U-Pb测年结果​​表明，石英闪长岩和花岗闪长岩的年龄范围分别为243±2Ma至244.8±1.3Ma和233.3±1.1Ma至233.6±1.5Ma。同期MME的锆石年龄与母岩相同，分别为244.5±1.1Ma-244.5±1.2Ma和233.7±1.3Ma。石英闪长岩和花岗闪长岩均含有角闪石，均表现出准铝质特征，平均A/CNK值分别为0.93和0.99，属于I型花岗岩。两者都富含大离子亲石元素，例如铷和Ba，而缺乏高场强元素，例如Nb和Ta。此外，它们的 ε() 值都较低，范围分别为 -5.6 至 -1.7 和 -5.4 至 -1.79。结果表明，HLZ 岩体源自部分熔融的新生镁铁质下地壳形成的岩浆。石英闪长岩因其 SiO 含量低而经历角闪石堆积。而花岗闪长岩的高 Sr/Y 比归因于磷灰石的分级结晶。值得注意的是，MME 中角闪石异晶的结晶压力和温度（平均 3.43 kbar 和 764 °C）与石英闪长岩中角闪石斑晶（平均 3.68 kbar 和 766 °C）接近。这种相似性表明石英闪长岩中的 MME 是由镁铁质岩浆与深地壳内的主岩之间的岩浆混合产生的。与母岩（平均 1.35 kbar 和 702 °C）相比，花岗闪长岩 MME 中存在的角闪石异晶含有更多数量的包裹体，显示出更高的结晶压力（平均 2.73 kbar）和温度（平均 825 °C）。这些结果表明，花岗闪长岩中的MME经历了两个不同的岩浆混合过程：镁铁质岩浆在地壳深处的岩浆混合，以及混合后的镁铁质岩浆进入花岗闪长岩后的上涌过程。