Transformation from Paleo-Asian Ocean closure to Paleo-Pacific subduction: New constraints from granitoids in the eastern Jilin-Heilongjiang Belt, NE China
Transformation from Paleo-Asian Ocean closure to Paleo-Pacific subduction: New constraints from granitoids in the eastern Jilin-Heilongjiang Belt, NE China
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从古亚洲洋闭合到古太平洋俯冲的转变：吉黑带东部花岗岩类的新约束
DOI：
10.1016/j.jseaes.2016.11.003
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发表时间：
2017-08-15
影响因子：
3
通讯作者：
Qiao, Shi-Lei
中科院分区：
文献类型：
--
作者：
Ma, Xing-Hua;Zhu, Wen -Ping;Qiao, Shi-Lei
吉林-黑龙江东带是中国东北部一个独特的造山带，在古亚洲和古太平洋构造体系中经历了两个阶段的演化。对EJHB及其邻近的俄罗斯锡霍特-阿林造山带（SAOB）中、新生代花岗岩类进行了158个可用锆石U-Pb年龄的整理和分析，其中本研究获得的年龄为26个，文献中已有的年龄为132个，目的是研究花岗岩类的时空分布，约束东亚大陆边缘的构造演化。花岗岩岩浆活动可划分为早三叠世（251 ~ 240 Ma）、晚三叠世（228 ~ 215 Ma）、晚三叠世至中侏罗世（213 ~ 158 Ma）、早白垩世（131 ~ 105 Ma）、晚白垩世至古新世（95 ~ 56 Ma）五个阶段。早三叠世花岗岩类局限于沿长春-延吉缝合线延边地区，具有下地壳源增厚岩浆的地球化学特征，可能是由于华北克拉通与东北板块的最终碰撞所致。晚三叠世花岗岩类以a型花岗岩为特征，代表了与造山后伸展有关的碰撞后岩浆活动，标志着古亚洲海洋构造演化的结束。最新的三叠纪—古新世花岗岩类具有钙碱性特征，沿EJHB和SAOB向ne向侵位，向沿海地区年轻化，代表了古太平洋板块向西北俯冲的大陆边缘弧岩浆。158 ~ 131 Ma和105 ~ 95 Ma两个岩浆静止期对应着古太平洋板块俯冲方向从相对大陆边缘斜向向亚平行方向的变化。综上所述，我们认为：(1)古亚洲洋的最终闭合发生在早三叠世的长春-延吉缝合带上；(2)古太平洋板块在东亚大陆边缘下的俯冲可能发生在晚三叠纪（约215 Ma）；(3)古太平洋板块漂移方向的变化是间歇性岩浆活动的主要原因；(4)早白垩世，俯冲板块的回滚导致岩浆弧向海洋迁移和大规模弧后伸展。(c) 2016 Elsevier Ltd.版权所有。
The eastern Jilin-Heilongjiang Belt (EJHB) of NE China is a unique orogen that underwent two stages of evolution within the tectonic regimes of the Paleo-Asian and Paleo-Pacific oceans. 158 available zircon U-Pb ages, including 26 ages obtained during the present study and 132 ages from the literature, were compiled and analyzed for the Mesozoic and Cenozoic granitoids from the EJHB and the adjacent Russian Sikhote-Alin Orogenic Belt (SAOB), to examine the temporal-spatial distribution of the granitoids and to constrain the tectonic evolution of the East Asian continental margin. Five stages of granitic magmatism can be identified: Early Triassic (251-240 Ma), Late Triassic (228-215 Ma), latest Triassic to Middle Jurassic (213-158 Ma), Early Cretaceous (131-105 Ma), and Late Cretaceous to Paleocene (95-56 Ma). The Early Triassic granitoids are restricted to the Yanbian region along the Changchun-Yanji Suture, and show geochemical characteristics of magmas from a thickened lower crust source, probably due to the final collision of the combined NE China blocks with the North China Craton. The Late Triassic granitoids, with features of A-type granites, represent post-collisional magmatic activities that were related to post-orogenic extension, marking the end of the tectonic evolution of the Paleo-Asian Ocean. The latest Triassic to Paleocene granitoids with calc-alkaline characteristics were NE-trending emplaced along the EJHB and SAOB and young towards the coastal region, and represent continental marginal arc magmas that were associated with the northwestwards subduction of the Paleo-Pacific Plate. Two periods of magmatic quiescence (158-131 and 105-95 Ma) correspond to changes in the subduction direction of the Paleo-Pacific Plate from oblique relative to the continental margin to subparallel. Taking all this into account, we conclude that: (1) the final closure of the Paleo-Asian Ocean occurred along the Changchun-Yanji Suture during the Early Triassic; (2) the onset of the subduction of the Paleo-Pacific Plate beneath the East Asian continental margin probably took place during the latest Triassic (ca. 215 Ma); (3) changes in the drifting direction of the Paleo-Pacific Plate were responsible for the intermittent magmatic activities; and (4) roll-back of the subducted plate resulted in the oceanwards migration of the magmatic arc and large-scale back-arc extension throughout NE China during the Early Cretaceous. (c) 2016 Elsevier Ltd. All rights reserved.