Devonian to Permian plate tectonic cycle of the Paleo-Tethys Orogen in southwest China (II): Insights from zircon ages of ophiolites, arc/back-arc assemblages and within-plate igneous rocks and generation of the Emeishan CFB province
Devonian to Permian plate tectonic cycle of the Paleo-Tethys Orogen in southwest China (II): Insights from zircon ages of ophiolites, arc/back-arc assemblages and within-plate igneous rocks and generation of the Emeishan CFB province
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中国西南古特提斯造山带泥盆纪-二叠纪板块构造旋回（二）：蛇绿岩锆石年龄、弧/弧后组合、板内火成岩及峨眉山CFB省的形成
DOI：
10.1016/j.lithos.2009.04.006
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发表时间：
2009-12
期刊：
影响因子：
3.5
通讯作者：
Dunyi Liu
中科院分区：
文献类型：
--
作者：
Qi Zhang;Alfred Kröner;Xiaomeng Sun;Ping Jian;Yizhao Wang;Wei Zhang;Dunyi Liu
蛇绿岩、弧/弧后组合和板内火成岩的SHRIMP锆石年龄制约了中国西南古特提斯造山带的演化。蛇绿岩代表古特提斯洋的残余，它被思茅海分成两个区域，即西部（现今位置）的主洋和东部的分支。主洋可能起源于早泥盆世冈瓦纳大陆的裂解，其遗迹为长宁-孟连蛇绿岩（SSZ型）。大洋分支以哀牢山（NMORB型）-金沙江（EMORB型）蛇绿岩为代表。哀牢山蛇绿岩中的闪长岩和斜长花岗岩的锆石206 Pb/238 U年龄分别为382.9± 3.9Ma和375.9± 4.2Ma。金沙江蛇绿岩堆晶辉长岩的年龄为343.5± 2.7Ma。昌宁-孟连蛇绿岩的变质辉长岩的结晶年龄为267.1± 3.1Ma。哀牢山和金沙江蛇绿岩的年龄反映了分支洋的海底扩张，而昌宁-孟连蛇绿岩的年龄则反映了主洋的闭合。弧/弧后组合（带状镁铁-超镁铁杂岩和弧火山岩）是会聚板块边界岩浆活动的记录。Gicha杂岩（弧后裂谷）的岩石获得的锆石年龄为：英云闪长岩306.2±4.6 Ma，微辉长岩301.0±2.9 Ma，斜长角闪长岩297.1±2.0 Ma，闪长岩281.3±1.7 Ma。半坡杂岩（深成弧）的辉长岩和英云闪长岩的年龄分别为285.6± 1.7Ma和285.8± 2.0Ma。雅仙桥火山弧玄武岩的年龄为266.2± 2.2Ma。板内火成岩也被定年。金沙江蛇绿混杂岩中的两个斜长角闪岩捕虏体的锆石年龄分别为439.3±3.5 Ma和403.7±3.1 Ma，代表了早于分支洋开启的大陆裂谷作用。小型大龙开分异镁铁质-超镁铁质岩体反映造山后伸展作用，具有叠加弧和板内地球化学特征。该岩体的斜长辉石岩锆石年龄为245.6± 1.4Ma。这些新的结果，结合地质和地球化学数据，允许重建泥盆纪至二叠纪的板块构造旋回，其中峨眉山CFB省的产生与古特提斯造山带在时间上相关。这一研究为多期造山作用导致的陆-洋-陆循环发展提供了证据，同时也为板块构造与大火成岩省形成之间的动力学关系提供了时间约束。
New SHRIMP zircon ages for ophiolites, arc/back-arc assemblages and within-plate igneous rocks constrain the evolution of the Paleo-Tethys Orogen of southwest China. Ophiolites represent remnants of the Paleo-Tethys ocean, which was divided by the Simao terrane into two tracts, the main ocean in the west (current position) and a branch in the east. The main ocean has been inferred to originate from Gondwana break-up in the Early Devonian, and the heritage is preserved as the Changning-Menglian ophiolite (SSZ-type). The oceanic branch is represented by the Ailaoshan (NMORB-type)–Jinshajinag (EMORB-type) ophiolites. Zircons from a diabase and a plagiogranite of the Ailaoshan ophiolite yielded206Pb/238U ages of 382.9±3.9 Ma and 375.9±4.2 Ma. The age of a cumulate gabbro from the Jinshajiang ophiolite is 343.5±2.7 Ma. A metagabbro of the Changning-Menglian ophiolite yielded a crystallization age of 267.1±3.1 Ma. We interpret the ages of the Ailaoshan and Jinshajiang ophiolites to represent sea-floor spreading in the branch ocean, whereas the age of the Changning-Menglian ophiolite reflects closure of the main ocean. Arc/back-arc assemblages (zoned mafic–ultramafic complexes and arc volcanic rocks) are records of convergent plate boundary magmatic activity. Rocks of the Gicha complex (back-arc rift) yielded zircon ages of 306.2±4.6 Ma for a tonalite, 301.0±2.9 Ma for a microgabbro, 297.1±2.0 Ma for a plagioclase hornblendite, and 281.3±1.7 Ma for a diabase. A gabbro and a tonalite of the Banpo complex (plutonic arc) yielded identical ages of 285.6±1.7 Ma and 285.8±2.0 Ma. A basalt of the Yaxianqiao volcanic arc was dated at 266.2±2.2 Ma. Within-plate igneous rocks were also dated. Two amphbolite xenoliths in the Jinshajiang ophiolite mélange, derived from low-Ti continental flood basalts, have zircon ages of 439.3±3.5 Ma and 403.7±3.1 Ma, which we interpret to represent the inception of continental rifting prior to the opening of the branch ocean. The small Dalongkai differentiated mafic–ultramafic intrusion reflects post-orogenic extension and is characterized by superimposed arc and within-plate geochemical signatures. Zircons from a plagioclase pyroxenite of this intrusion yielded an age of 245.6±1.4 Ma. These new results, combined with geological and geochemical data, allow the reconstruction of a Devonian to Permian plate tectonic cycle in which generation of the Emeishan CFB province correlates with Paleo-Tethys orogeny in time. This study provides evidence for cyclic continent–ocean–continent development via multiple orogenesis, as well as temporal constraints on the dynamic relationship between plate tectonics and generation of a large igneous province.
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影响因子：
4.9
作者：
J. Shervais;B. Murchey;D. Kimbrough;P. Renne;B. Hanan
通讯作者：
J. Shervais;B. Murchey;D. Kimbrough;P. Renne;B. Hanan
影响因子：
5.3
作者：
STEIGER, RH;JAGER, E
通讯作者：
JAGER, E
影响因子：
5.8
作者：
A. Draut;P. Clift
通讯作者：
A. Draut;P. Clift
影响因子：
4.9
作者：
K. Kodama;P. Ward
通讯作者：
K. Kodama;P. Ward
DOI：
--
发表时间：
2002
期刊：
Geological Review
影响因子：
--
作者：
L. Dun-yi
通讯作者：
L. Dun-yi