The Heilongjiang Group: A Jurassic accretionary complex in the Jiamusi Massif at the western Pacific margin of northeastern China
The Heilongjiang Group: A Jurassic accretionary complex in the Jiamusi Massif at the western Pacific margin of northeastern China
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DOI：
10.1111/j.1440-1738.2007.00564.x
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发表时间：
2007-03
期刊：
影响因子：
1.5
通讯作者：
Fu-Yuan Wu;Jin-Hui Yang;C. Lo;S. Wilde;Dejun Sun;B. Jahn
中科院分区：
文献类型：
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作者：
Fu-Yuan Wu;Jin-Hui Yang;C. Lo;S. Wilde;Dejun Sun;B. Jahn
东亚大陆边缘侏罗纪的构造背景一直存在争议。为了解决这一问题，本研究选择了位于佳木斯地块西缘的黑龙江杂岩进行年代学调查。野外和岩石学研究表明，黑龙江杂岩主要由花岗质片麻岩、大理岩、镁铁质-超镁铁质岩、蓝片岩、绿片岩、石英岩、白云母-钠长石片岩和二云母片岩组成，它们在构造上互为交错，表明它们是一个混纺体。大理岩、二云母片岩和花岗质片麻岩极有可能来自佳木斯地块马山杂岩，这是一个与黑龙江群关系密切的优质片麻岩杂岩。超镁质岩、蓝片岩、绿片岩和石英岩（燧石）与蛇绿岩成分相似。花岗质片麻岩的U - Pb锆石年龄为265±4 Ma，表明该花岗质片麻岩原岩花岗岩与佳木斯地块二叠纪岩基共埋。花岗质片麻岩和云母片岩中的黑云母和云母云母的40Ar/39Ar定年结果表明，该花岗质片麻岩变质年龄为早侏罗世晚期的184 ~ 174 Ma。佳木斯地块的早期组成部分，包括马山杂岩，可能是冈瓦纳的一个外来地块的一部分，受晚泛非造山运动的影响，并在早侏罗世与亚洲大陆边缘碰撞。佳木斯地块与中亚造山带东部之间的洋壳俯冲作用，使张广才山脉形成了大量侏罗纪花岗岩。因此，佳木斯地块与西部中亚造山带的碰撞可以认为是环太平洋增生的结果，与中亚造山带无关。侏罗纪增生杂岩在亚洲大陆边缘的广泛发育支持了这种解释。
Abstract The tectonic setting of the Eastern Asian continental margin in the Jurassic is highly controversial. In the current study, we have selected the Heilongjiang complex located at the western margin of the Jiamusi Massif in northeastern China for geochronological investigation to address this issue. Field and petrographic investigations indicate that the Heilongjiang complex is composed predominately of granitic gneiss, marble, mafic‐ultramafic rocks, blueschist, greenschist, quartzite, muscovite‐albite schist and two‐mica schist that were tectonically interleaved, indicating they represent a mélange. The marble, two‐mica schist and granitic gneiss were most probably derived from the Mashan complex, a high‐grade gneiss complex in the Jiamusi Massif with which the Heilongjiang Group is intimately associated. The ultramafic rocks, blueschist, greenschist and quartzite (chert) are similar to components in ophiolite. The sensitive high mass‐resolution ion microprobe U‐Pb zircon age of 265 ± 4 Ma for the granitic gneiss indicates that the protolith granite was emplaced coevally with Permian batholiths in the Jiamusi Massif. 40Ar/39Ar dating of biotite and phengite from the granitic gneiss and mica schist yields a late Early Jurassic metamorphic age between 184 and 174 Ma. Early components of the Jiamusi Massif, including the Mashan complex, probably formed part of an exotic block from Gondwana, affected by late Pan‐African orogenesis, and collided with the Asian continental margin during the Early Jurassic. Subduction of oceanic crust between the Jiamusi block and the eastern part of the Central Asian Orogenic Belt resulted in the formation of a huge volume of Jurassic granites in the Zhangguangcai Range. Consequently, the collision of the Jiamusi Massif with the Central Asian Orogenic Belt to the west can be considered as the result of circum‐Pacific accretion, unrelated to the Central Asian Orogenic Belt. The widespread development of Jurassic accretionary complexes along the Asian continental margin supports such an interpretation.