A Triassic-Jurassic westward scissor-like subduction history of the Mudanjiang Ocean and amalgamation of the Jiamusi Block in NE China: Constraints from whole-rock geochemistry and zircon U-Pb and Lu-Hf isotopes of the Lesser Xing'an-Zhangguangcai Ra
A Triassic-Jurassic westward scissor-like subduction history of the Mudanjiang Ocean and amalgamation of the Jiamusi Block in NE China: Constraints from whole-rock geochemistry and zircon U-Pb and Lu-Hf isotopes of the Lesser Xing'an-Zhangguangcai Ra
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牡丹江洋三叠纪—侏罗纪西剪式俯冲历史与中国东北佳木斯地块的拼合:小兴安岭-张广才Ra全岩地球化学及锆石U-Pb、Lu-Hf同位素的制约
DOI：
10.1016/j.lithos.2018.01.004
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发表时间：
2018
期刊：
影响因子：
3.5
通讯作者：
Liu Kai
中科院分区：
文献类型：
--
作者：
Ge Mao-Hui;Zhang Jin-Jiang;Li Long;Liu Kai
中国东北地区记录了欧亚板块从中亚造山带古生代-中生代碰撞形成到古太平洋中生代俯冲的关键构造演化历史。为了更好地理解这种构造转变，限制古太平洋初始俯冲的时间和模式至关重要。近年来，有研究人员提出松嫩地块与佳木斯地块之间的牡丹江洋是古太平洋的一部分。通过对松嫩地块东部小兴安岭-张广才岭广泛分布的花岗岩的地球化学和年代学研究，我们证实这些岩浆岩表现出与火山弧的亲和力，从东到西地幔贡献增加，这可能与牡丹江洋的扁平俯冲有关。此外，小兴安岭-张广才岭花岗岩类普遍存在70马币以上的向西年轻化趋势，表明牡丹江洋存在长期俯冲作用。更有趣的是，东部花岗岩最古老的年龄在275 Ma至218 Ma之间呈现出向北年轻的趋势，这表明牡丹江洋的俯冲作用最晚在南部275 Ma开始，然后逐渐向北部扩展。在此基础上，我们提出了牡丹江洋新的构造演化模式，即三叠纪—侏罗纪向西剪刀状俯冲闭合，为认识古太平洋早期俯冲做出贡献。 (C) 2018 Elsevier B.V. 保留所有权利。
NE China recorded the key tectonic evolution history of the Eurasian Plate from the Paleozoic-Mesozoic collisional formation of the Central Asian Orogenic Belt to the Mesozoic subduction of the Paleo-Pacific Ocean. To better understand this tectonic transition, it is crucial to constrain the time and pattern of the initial subduction of the Paleo-Pacific Ocean. Recently, some researchers proposed that the Mudanjiang Ocean existed between the Songnen and Jiamusi blocks was part of the Paleo-Pacific Ocean. Here, through geochemical and geochronological studies on the widespread granitoids in the Lesser Xing'an-Zhangguangcai Range in the eastern Songnen Block, we verify that these magmatic rocks show volcanic arc affinity with increased mantle contribution from east to the west of the range, likely related to a flattening subduction of the Mudanjiang Ocean. In addition, a universal westward younging trend for over 70 Myr can be observed for the granitoids throughout the Lesser Xing'an-Zhangguangcai Range, indicating a long-lasting subduction of the Mudanjiang Ocean. More interestingly, the oldest ages of the granitoids in the east display a northward younging trend from 275 Ma to 218 Ma, suggesting that the subduction of the Mudanjiang Ocean had been initiated at latest by 275 Ma in the south and then progressively expanded to the north. Based on these observations, we proposed a new tectonic evolution model for the Mudanjiang Ocean, i.e., a Triassic-Jurassic westward scissor-like subduction and closure, to contribute to the understanding of the early subduction of the Paleo-Pacific Ocean. (C) 2018 Elsevier B.V. All rights reserved.