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首页> 外文期刊>International Geology Review >SHRIMP U-Pb zircon geochronology and Hf isotope analyses of Middle Permian-early triassic intrusions in southern Manzhouli area, Northeast China: implications for the subduction of Mongol-Okhotsk plate beneath the Erguna massif
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SHRIMP U-Pb zircon geochronology and Hf isotope analyses of Middle Permian-early triassic intrusions in southern Manzhouli area, Northeast China: implications for the subduction of Mongol-Okhotsk plate beneath the Erguna massif

机译：虾U-PB锆石上传学和HF同位素分析中缅早期三叠纪侵入地区，东北地区南部地区：Erguna Massif下面的蒙古 - Okhotsk板胶片的影响

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The results of SHRIMP U-Pb ages and in situ Hf isotope of zircons from three granites in the southern Manzhouli region of northeast China, provide new data to understand the subduction process of Mongol-Okhotsk Plate beneath the Erguna massif. SHRIMP U-Pb zircon geochronology results yield an age of 265.5 Ma (middle Permian) for fine-grained monzogranite. Rocks from the Early-Middle Triassic are mainly granodiorite (247.4 +/- 4.6 and 249.3 +/- 4.9 Ma), the granites are with SiO2 = 60.0-77.4 wt.%, Al2O3 = 12.3-16.8wt.% and Na2O/K2O = 0.7-1.9. Chemically, they are metaluminous to peraluminous and belong to the high-K calc-alkaline series. Enrichments in the large ion lithophile elements (e.g., Rb, Ba, and K) and depletions in the high field strength elements (e.g., Nb, Ta, and Ti) are typical for these rock types. The monzogranite (similar to 265 Ma) and granodiorite (similar to 247 Ma) contain zircons with epsilon Hf(t) values of 6.3-8.5 and 5.1-7.9, yielding T-DM2 model ages of 888-752 and 958-774 Ma, respectively. These geochemical and zircon Hf isotopic data indicate that primary magmas for Middle Permian-Early Triassic granites crystallized from primary magmas generated by Neoproterozoic crustal materials, formed in an active continental margin setting. The andesite of the Gegenaobao formation is similar with the Izu-Bonin-Mariana arc, relating to subduction initiation. Based on the characteristics of exposed rocks and zircon U-Pb ages of andesite and granitoid rocks in the study area, we conclude the onset subduction of Mongol-Okhotsk Plate beneath the Erguna massif may occur at early-middle Permian.
机译：虾U-Pb年龄和原位HF同位素的Zircons在东北南部曼庄地区的三个花岗岩中，提供了新数据，了解Erguna Massif下面的蒙古Okhotsk板的俯冲过程。虾U-PB锆石上色结果为265.5 mA（中二叠纪）的粒子蒙扎石。来自早期三叠系的岩石主要是Granodiorite（247.4 +/- 4.6和249.3 +/- 4.9 mA），花岗岩配有SiO2 = 60.0-77.4重量％，Al2O3 = 12.3-16.8wt。％和Na2O / K2O = 0.7-1.9。化学上，它们是毫黄的金属滤光剂，属于高k钙碱系列。对于这些岩石类型，大离子型鳞片元素（例如，Rb，Ba和k）和耗尽的富集在高场强元件（例如，Nb，Ta和Ti）中是典型的。蒙扎石石（类似于265 mA）和Granodiorite（类似于247 mA）含有ePsilon HF（T）值的锆石，为6.3-8.5和5.1-7.9，产生888-752和958-774 mA的T-DM2型号，分别。这些地球化学和锆石的同位素数据表明，用于中间二叠岩的主要岩浆岩浆从由NeoProtero古古代地壳材料产生的原发性岩棉结晶，形成在有源大陆边缘环境中。 Gegenaobao形成的嵌和岩与苏邦 - 玛丽安娜弧相似，与俯冲开始有关。基于研究区域的暴露岩石和锆石U-PB衰龄的特点，我们得出了在早期二叠代早期二叠纪中可能出现的erguna MaseIF下面的蒙古 - Okhotsk板的起始胶片。

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