One or Two Early Cretaceous Arc Systems in the Lhasa Terrane, Southern Tibet
One or Two Early Cretaceous Arc Systems in the Lhasa Terrane, Southern Tibet
复制标题
藏南拉萨地体一两个早白垩世弧系
DOI：
10.1002/2018jb015582
复制
发表时间：
2018-05
期刊：
影响因子：
--
通讯作者：
Zhao Zhidan
中科院分区：
文献类型：
--
作者：
Li Shi-Min;Wang Qing;Zhu Di-Cheng;Stern Robert J.;Cawood Peter A.;Sui Qing-Lin;Zhao Zhidan
与岛弧有关的岩浆活动的时空变化是确定不完全保存的岛弧系统俯冲极性的关键。拉萨地体北方盐湖周围早白垩世火山岩的岩相学、年代学、地球化学和同位素资料表明，班公特提斯曾向南俯冲。两个不同的钙碱性岩浆序列被确认：较老的中钾玄武岩和富镁安山岩（131-116 Ma）和较年轻的高钾玄武岩和粗安岩（116-110 Ma）。中钾玄武岩表现出典型的弧签名，而中钾安山岩显示较高的MgO含量相对于弧安山岩。中钾系列被解释为在较低压力和较大水活度下，交代地幔楔源的部分熔融，生成富镁安山岩。高钾系列以富集高度不相容元素为特征，被认为是被交代的软流圈地幔源区的低度部分熔融。所有样品都显示出与弧有关的特征，这表明我们称之为拉萨地体北方班戈-盐湖弧的发展。结合拉萨地体上早白垩世弧岩浆活动的分布prior.to随后的变形宽度至少为600 km），认为拉萨地体两侧存在两个与大洋板块相对俯冲有关的弧系：新特提斯的北倾俯冲和班公特提斯的南倾俯冲。盐湖周边中钾-高钾钙碱性火山岩的成分变化记录了地幔动力学的变化，推测反映了班公湖特提斯板块南倾的回滚和断裂。
Spatial and temporal variations of arc-related magmatism are key to determining the.subduction polarity of incompletely preserved arc systems. Petrographic, geochronological, geochemical,.and isotope data of Early Cretaceous volcanic rocks from the northern Lhasa Terrane around Yanhu indicate.south dipping subduction of the Bangong Tethys. Two distinct calc-alkaline magmatic successions are.recognized: older medium-K basalts and Mg-rich andesites (131–116 Ma), and younger high-K basalts and.trachyandesites (116–110 Ma). The medium-K basalts exhibit a typical arc signature, whereas the medium-K.andesites show higher MgO contents relative to arc andesites. The medium-K series are interpreted as partial.melting of a metasomatized mantle wedge source at lower pressure and greater water activity in.generating the Mg-rich andesites. The high-K series are characterized by enrichments in highly.incompatible elements and are considered as low-degree partial melting of asthenosphere mantle source.that was previously metasomatized. All samples show arc-related signatures, which indicate the.development of what we term the Baingoin-Yanhu arc in the northern Lhasa Terrane. This observation, in.combination with the distribution of Early Cretaceous arc magmatism across the Lhasa Terrane, which prior.to subsequent deformation had a width of at least 600 km, requires the existence of two arc systems.flanking the Lhasa Terrane and related to opposed oceanic plate subduction: north dipping subduction of.the Neo-Tethys and south dipping subduction of the Bangong Tethys. Compositional change from.medium-K to high-K calc-alkaline volcanism around Yanhu records changing mantle geodynamics, which.we infer to reflect rollback and breakoff of the south dipping Bangong Tethyan slab.
登录
查看更多内容
西藏羌塘南部中生代花岗岩体锆石U-Pb年龄和Hf同位素组成：对班公怒江特提斯洋俯冲的启示
影响因子：
6.1
作者：
Qishuai Huang;Xiaoran Zhang;Yahui Yue;Liyun Zhang
通讯作者：
Liyun Zhang
影响因子：
4.6
作者：
Bian W;Yang T;Ma Y;Jin J;Gao F;Zhang S;Wu H;Li H
通讯作者：
Li H
青藏高原拉萨地体狮泉河-云珠-纳木措蛇绿岩带云珠蛇绿岩成因的年代学和地球化学约束
影响因子：
3.5
作者：
Zeng Y.C.;Xu J.F.;Chen J.L.;Wang B.D.;Kang Z.Q.;Huang F.
通讯作者：
Huang F.
影响因子：
3.5
作者：
Jinxiang Li;K. Qin;Guangming Li;J. Richards;Junxing Zhao;Mingjian Cao
通讯作者：
Jinxiang Li;K. Qin;Guangming Li;J. Richards;Junxing Zhao;Mingjian Cao
再访日喀则弧前盆地（藏南）：日喀则蛇绿岩的物源变化与成因
影响因子：
4.9
作者：
Garzanti, Eduardo;BouDagher-Fadel, Marcelle K.;Wang, Jiangang;Sun, Gaoyuan
通讯作者：
Sun, Gaoyuan