中天山、伊犁及塔里木地块开始参与Rodinia超大陆聚合过程早于新元古代?
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本文为中国自然科学基金项目(编号41502198、41872121及41302166)、博士后科学基金项目(编号2015M571083、2016T90122)、中国地质科学院基本科研业务项目(编号JYYWF20180903、JYYWF20182103)及中国地质调查局地调地质调查项目(编号: DD20190060及DD20190006)联合资助成果。


The initial assembly of the Chinese Central Tianshan, Yili and Tarim blocks to the Rodinia supercontinent prior to the Early Neoproterozoic?
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    摘要:

    长久以来,中国主要陆块被普遍认为比世界其他陆块开始参与罗迪尼亚超大陆聚合的时间较晚,为新元古代早期。为了探讨此问题,我们选择中国中天山、伊犁及塔里木地块作为主要研究对象,系统分析了新元古代早期(1. 0~0. 8 Ga)的构造变形及岩浆特征。新元古代早期构造变形主要表现为拉伸线理近平行于造山带方向,反映了后造山陆内走滑剪切过程。1. 0~0. 8 Ga的岩浆岩皆为较小规模花岗岩,未见基性包体,矿物组合中基本无角闪石,具有高钾钙碱性和过铝质特征,并含有大量捕获老锆石,说明古老基底或重熔地壳的显著参与。岩石源区主要为重熔基性下地壳,在构造背景判别图上基本落在后造山环境。锆石Ti及全岩Zr温度计算结果显示这些岩体的结晶温度普遍偏高,约800℃。结合已有区域地质资料,我们认为:①在新元古代原塔里木陆块(包括早期中天山、伊犁及塔里木地块)已经位于罗迪尼亚超大陆内部,1. 0~0. 8 Ga变形及岩浆记录皆反映了原塔里木陆块与其它陆块碰撞后的构造事件;②由于超大陆聚合后的热毯效应使得新元古代早期花岗岩结晶温度偏高;③中天山、伊犁及现今塔里木地块最初参与罗迪尼亚超大陆汇聚的时间应早于新元古代(>1. 0 Ga)。

    Abstract:

    The main Chinese blocks has been long thought to assemble to the Rodinia supercontinent later than other blocks around the globe. In the present study, we selected the Chinese Central Tianshan, Yili and Tarim blocks to test this hypothesis. We systematically analyzed the deformation and magma characteristics in the early Neoproterozoic (1. 0-0. 8 Ga). The lineation of the Neoproterozoic deformed rocks is nearly parallel to the trend of the orogenic belt, reflecting an intracontinental strikeslip shearing in the postorogeny. The 1. 0-0. 8 Ga magmatic rocks are smallscale granites, no mafic enclaves, no or minor hornblendes in the mineral assemblage, showing highK calcalkaline affinity and peraluminous characteristics, with abundant inherited zircons, with the melting of lower crust as the main source and falling into postcollisional setting. The Tiinzircon and Zrinwholerock geothermometers yield high crystallization temperatures (ca. 800℃) for these plutons. In combination with regional geology, we suggest that ① the Chinese Central Tianshan, Yili and Tarim blocks (belonging to the Greater Tarim Block) had been located in the interior of the Rodinia supercontinent and finished the collisional processes with other blocks during early Neoproterozoic, The deformation and magmatic records of 1. 0-0. 8 Ga reflect a tectonic event after continental collision. ② The high magmatic temperature can be explained as the thermal blanket effect from the supercontinent assembly. ③ The time of the initial assembly of the Greater Tarim Block (Chinese Central Tianshan, Yili and the present Tarim blocks) to the Rodinia supercontinent is prior to the Early Neoproterozoic (>1. 0 Ga).

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蔡志慧,马绪宣,何碧竹.2019.中天山、伊犁及塔里木地块开始参与Rodinia超大陆聚合过程早于新元古代?[J].地质学报,93(10):2426-2445.
CAI Zhihui, MA Xuxuan, HE Bizhu.2019. The initial assembly of the Chinese Central Tianshan, Yili and Tarim blocks to the Rodinia supercontinent prior to the Early Neoproterozoic?[J]. Acta Geologica Sinica,93(10):2426-2445.

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  • 收稿日期:2019-07-06
  • 最后修改日期:2019-08-31
  • 录用日期:2019-09-02
  • 在线发布日期: 2019-09-12