Neoproterozoic Subduction and Rifting on the Northern Margin of the yangtze Plate, China: Implications for Rodinia Reconstruction
Neoproterozoic Subduction and Rifting on the Northern Margin of the yangtze Plate, China: Implications for Rodinia Reconstruction
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DOI：
10.2747/0020-6814.46.9.817
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发表时间：
2004-09
影响因子：
2.6
通讯作者：
Q. Yan;A. Hanson;Zong-qi Wang;P. Druschke;Zhen Yan;Tao Wang;Dunyi Liu;B. Song;P. Jian;
中科院分区：
文献类型：
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作者：
Q. Yan;A. Hanson;Zong-qi Wang;P. Druschke;Zhen Yan;Tao Wang;Dunyi Liu;B. Song;P. Jian;
碧口地体位于中国中部秦岭西南部，靠近扬子板块北缘，其与扬子板块晚前寒武纪构造史的关系一直存在争议。碧口地体的火成岩和沉积序列被不同地解释为中-新元古代裂谷组合或俯冲弧组合。我们最近在火成岩岩石地球化学和沉积盆地分析方面的工作有力地支持了俯冲弧的解释。此外，对口弧火山岩的SHRIMP U-Pb锆石定年结果表明，新元古代（~846 ~ 776 Ma）扬子板块北缘发生了俯冲作用。此外，璧口弧镁质岩脉群的40Ar/39Ar和SHRIMP U-Pb新年龄表明侵位发生在晚新元古代，~689 ~ 660 Ma。因此，火山作用的年龄与先前提出的与华南地块（SCB）有关的伸展相关的地幔上涌和罗迪尼亚分裂是一致的，因此是不相容的。我们认为扬子板块在格伦维尔造山运动末期与华夏地块碰撞形成南海板块，并在新元古代（~846 ~ 776 Ma）沿其北缘发育了一条长寿命的俯冲弧。形成南海被动边缘的后续裂谷作用可能在689 ~ 660 Ma之间开始。
Located in the southwestern Qinling Mountains of central China near the northern margin of the yangtze plate, the Bikou terrane has long been controversial regarding how it relates to the Late Precambrian tectonic history of the yangtze plate. The igneous and sedimentary succession of the Bikou terrane has been variously interpreted to represent either a Meso-Neoproterozoic rift assemblage, or a subduction arc assemblage. Our recent work involving igneous petrologygeochemistrysedimentary basin analysis strongly supports the subduction arc interpretation. In addition, SHRIMP U-Pb zircon dating of volcanic rocks from the Bikou arc reveal that subduction occurred along the northern margin of the yangtze plate in the Neoproterozoic, ~846-776 Ma. Additionallynew 40Ar/39Ar and SHRIMP U-Pb ages of mafic dike swarms in the Bikou arc indicate emplacement occurred in the Late Neoproterozoic, ~689-660 Ma. Therefore the age of volcanism is coincident with, and thus incompatible with, previously proposed extension-related mantle upwelling and break-up of Rodinia involving the South China Block (SCB). We propose that the yangtze plate collided with the Cathaysian Block at the end of the Grenville orogeny to form the SCB, and subsequently developed a long-lived subduction-related arc along its northern margin in the Neoproterozoic, ~846-776 Ma. Subsequent rifting that formed the passive margin of the SCB may have been initiated ~689-660 Ma.