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首页> 外文OA文献 >Geochronology and geochemistry of Late Cretaceous–Paleocene granitoids in the Sikhote-Alin Orogenic Belt : petrogenesis and implications for the oblique subduction of the paleo-Pacific plate.
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Geochronology and geochemistry of Late Cretaceous–Paleocene granitoids in the Sikhote-Alin Orogenic Belt : petrogenesis and implications for the oblique subduction of the paleo-Pacific plate.

机译：Sikhote-Alin造山带晚白垩世-古新世花岗岩类的年代学和地球化学：岩石成因及其对古太平洋板块俯冲作用的影响。

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摘要

We present zircon U–Pb ages, major and trace element analyses, and zircon Hf isotope data on the Late Cretaceous–Paleocene granitoids at the southern end of the Sikhote-Alin Orogenic Belt of the Russian Far East. These data are used to discuss the petrogenesis of the granitoids in the context of the paleo-Pacific subduction beneath the eastern Eurasia. Zircons from four granitoid samples give emplacement ages of ~ 56, ~ 83, ~ 91, and ~ 92 Ma. These granitoids with high SiO2 (73.43–76.76 wt%) are metaluminous to weakly peraluminous (A/CNK = 0.97–1.03) and belong to the high-K calc-alkaline series (K2O = 3.75–4.95 wt%). They are all enriched in light rare earth elements (LREEs) and large ion lithophile elements (LILEs), and relatively depleted in high field strength elements (HFSEs) with striking depletion also in Ba, Sr, P and Eu. They are petrographically and geochemically consistent with being of I-type granitoids. The zircons have εHf (t) values (− 0.8 to + 7.6) higher than whole-rock εHf (t) values predicted from whole-rock εNd (t) (− 4.1 to + 0.5) in the literature. All these observations suggest that primary magmas parental to these granitoids were likely to have derived from partial melting of a juvenile lower crust accompanied by assimilation with ancient mature crust during magma ascent and evolution. A recent study illustrates that the collision of an exotic terrane carried by the paleo-Pacific plate with the continental China at ~ 100 Ma accreted the basement of the Chinese continental shelf (beneath East and South China Seas), and resulted in a new plate boundary of transform nature between the NNW moving paleo-Pacific plate and the eastern margin of the shelf. Our new data and analysis of existing data support this hypothesis, but we hypothesize that this transform becomes transpressional in its northern segment with oblique subduction of the paleo-Pacific plate beneath northeastern Asia as manifested by the Late Cretaceous-Paleocene granitoids in the Russian Far East-NE China (97–56 Ma) and South Korea-SW Japan (96–71 Ma). These tectonic and magmatic events took place prior to the opening of the Huanghai, Bohai and Japan seas, which are of rift-origin from continental China much later. Our study emphasizes the necessity and significance of plate tectonics reconstruction in the greater northwestern Pacific region since the Cretaceous.
机译：我们介绍了俄罗斯远东Sikhote-Alin造山带南端的晚白垩世-古新世花岗岩类锆石的U–Pb年龄，主要和微量元素分析以及锆石Hf同位素数据。这些数据用于讨论欧亚大陆东部古太平洋俯冲作用下花岗岩的成岩作用。四个花岗岩样品中的锆石的定位年龄分别为〜56，〜83，〜91和〜92 Ma。这些具有高SiO2（73.43–76.76 wt％）的花岗石是金属铝至弱铝质（A / CNK = 0.97–1.03），属于高K钙碱性系列（K2O = 3.75–4.95 wt％）。它们都富含轻稀土元素（LREE）和大离子亲石性元素（LILE），并且相对贫乏高场强元素（HFSE），Ba，Sr，P和Eu的消耗也很显着。它们在岩石学和地球化学上与I型花岗岩类一致。锆石的εHf（t）值（-0.8至+ 7.6）高于文献中根据整体岩石εNd（t）预测的整体岩石εHf（t）值（-4.1至+ 0.5）。所有这些观察结果表明，这些花岗岩类的母岩浆可能是由于岩浆上升和演化过程中少年下地壳的部分融化以及与古代成熟地壳的同化而产生的。最近的一项研究表明，古太平洋板块所携带的一个奇异的地层与中国大陆在约100 Ma的碰撞使中国大陆架的基底（东海和南海下方）增生，并形成了一个新的板块边界西北太平洋移动的古太平洋板块与陆架东缘之间的转换性质。我们的新数据和对现有数据的分析支持了这一假设，但我们假设这种转换在其北段变为压性，而东北亚下方的古太平洋板块斜向俯冲，这在俄罗斯远东地区的晚白垩世-古新纪花岗岩体中就可以看出。 -NE中国（97-56 Ma）和韩国-SW日本（96-71 Ma）。这些构造和岩浆事件是在黄海，渤海和日本海开放之前发生的，黄海，裂​​谷和日本海是后来起源于中国大陆的裂谷。我们的研究强调了自白垩纪以来西北大太平洋地区板块构造重建的必要性和意义。

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