When did the subduction first initiate in the southern Paleo-Asian Ocean: New constraints from a Cambrian intra-oceanic arc system in West Junggar, NW China
When did the subduction first initiate in the southern Paleo-Asian Ocean: New constraints from a Cambrian intra-oceanic arc system in West Junggar, NW China
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古亚洲洋南部俯冲何时开始：来自中国西准噶尔寒武纪洋内弧系统的新约束
DOI：
10.1016/j.epsl.2013.11.055
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发表时间：
2014-02
影响因子：
5.3
通讯作者：
韩宝福
中科院分区：
文献类型：
--
作者：
韩宝福
本文报道了中国西缘南部寒武纪向南俯冲的洋内弧系统，其中未成熟的弧最初出现在SSZ型蛇绿岩上，最后演化为较成熟的弧。未成熟弧以早-中寒武世(∼510 Ma)低钾拉斑玄武岩为主，成熟弧以晚寒武世(∼495 Ma)中、高钾钙碱性长英质和镁铁质岩石为特征。SSZ型蛇绿岩具有明显的Nb、Ta亏损特征，并含有高铬尖晶石(Cr#&Gt；0.6)，与前弧形成的蛇绿岩相似。总之，它们记录了中亚造山带(CAOB)南部古亚洲洋早期俯冲过程中地壳的俯冲和改造。俯冲作用可能发生在早寒武世(&Gt；515 Ma)，受SSZ型蛇绿岩(516 Ma)和横穿蛇绿岩的最古老的弧状深成岩体(515-509 Ma)的制约。未成熟长英质深成岩体具有较高的SiO_2(>；72wt%)含量和可变的MgO(0.42~1.49wt%)和Mg#值(22~62)。地壳深成作用可能是这些深成岩类的成因，从而导致洋壳向陆壳的转化。这些结果，结合区域数据，令人信服地表明，它是CAOB南部最古老的洋内弧系之一，可能标志着古亚洲洋在其南部的首次俯冲，远远晚于北部的报道。提出了西准噶尔南部的群岛型演化模式，并对CAOB南部的发展提出了启示。
We report here a Cambrian southward-subducting intra-oceanic arc system in the southern West Junggar, NW China, where an immature arc occurred initially on SSZ-type ophiolites and finally evolved into a more mature one. The immature arc is dominantly represented by Early–Middle Cambrian (∼510 Ma) low-K tholeiitic felsic rocks, whereas the mature arc is characterized by Late Cambrian (∼495 Ma) medium- and high-K calc-alkaline felsic and mafic rocks. The SSZ-type ophiolites show remarkable depletion of Nb and Ta and contain high-Cr spinel (Cr# > 0.6), resembling these formed in the forearc. Altogether, they record the initiation of subduction and transformation of crust during early subduction of the Paleo-Asian Ocean in the southern part of the Central Asian Orogenic Belt (CAOB). The subduction initiation might occur in the Early Cambrian (>515 Ma), as constrained by both the SSZ-type ophiolites (516 Ma) and the oldest arc plutons (515–509 Ma) that crosscut the ophiolites. The immature felsic plutons have high SiO2(>72 wt%) contents and variable MgO (0.42–1.49 wt%) and Mg# values (22–62). Crustal anatexis may be responsible for the genesis of those plutons and thus the transformation from oceanic to continental crust. These results, combined with regional data, convincingly indicate that it is one of the oldest intra-oceanic arc systems in the southern CAOB, which may mark the initial subduction of the Paleo-Asian Ocean in its southern part, much later than those reported in the north. An archipelago-type model is proposed for the evolution of the southern West Junggar and has implications for the development of the southern part of the CAOB.
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影响因子：
4.9
作者：
Stephanie M. Briggs;A. Yin;C. Manning;Zhengle Chen;Xiao-feng Wang;M. Grove
通讯作者：
Stephanie M. Briggs;A. Yin;C. Manning;Zhengle Chen;Xiao-feng Wang;M. Grove
影响因子：
3.9
作者：
J. Pearce;P. E. Baker;P. Harvey;I. W. Luff
通讯作者：
J. Pearce;P. E. Baker;P. Harvey;I. W. Luff
影响因子：
1.8
作者：
Zhu Yong
通讯作者：
Zhu Yong
DOI：
10.1144/gsl.sp.2003.219.01.05
发表时间：
2003
期刊：
Geological Society, London, Special Publications
影响因子：
--
作者：
I. Smith;T. Worthington;R. Stewart;R. Price;J. Gamble
通讯作者：
I. Smith;T. Worthington;R. Stewart;R. Price;J. Gamble
影响因子：
3.5
作者：
Taofa Zhou;F. Yuan;Yu Fan;Dayu Zhang;D. Cooke;Guochun Zhao
通讯作者：
Taofa Zhou;F. Yuan;Yu Fan;Dayu Zhang;D. Cooke;Guochun Zhao