A general model of arc-continent collision and subduction polarity reversal from Taiwan and the Irish Caledonides
A general model of arc-continent collision and subduction polarity reversal from Taiwan and the Irish Caledonides
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DOI：
10.1144/gsl.sp.2003.219.01.04
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发表时间：
2003
期刊：
影响因子：
--
通讯作者：
P. Clift;H. Schouten;A. Draut
中科院分区：
文献类型：
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作者：
P. Clift;H. Schouten;A. Draut
吕宋弧与中国南部的碰撞代表了现代大洋中弧-陆碰撞的最好例子，并与爱尔兰康涅马拉湖的纳福伊湖弧早奥陶世到劳伦西亚被动边缘的吸积作用进行了比较。提出了稳态弧陆碰撞的一般模型，即弧壳在被动边缘的任何一个位置经历了持续3-10 Ma的挤压、变质和岩浆作用过程，逐渐增加到被动边缘。根据碰撞角度的倾角，活动碰撞的时间可能是历时的和沿边缘长期存在的。与碰撞前亏损的岩浆活动相比，伴随着增生作用的岩浆活动可以比一般陆壳更加富含不相容的微量元素。贫化和富集弧的混合岩性在大陆边缘的吸积使大陆地壳通过弧被动边缘碰撞事件随着时间的推移而生长。在碰撞过程中，上、中弧地壳从亏损的超镁铁质下地壳中分离出来，并与形成该弧的地幔岩石圈一起俯冲。碰撞造山带的快速(2-3 Ma)折返和重力崩塌分别在台湾和爱尔兰西部形成了冲绳海槽和南马约海槽。这些盆地由邻近碰撞带侵蚀的碎屑充填。在随后的俯冲极性反转过程中，大洋岩石圈沿着先前的陆-洋转换不断撕裂和撤退，为新的俯冲大洋板块提供了下降的空间，而不需要打破原始板块。
Abstract The collision of the Luzon Arc with southern China represents the best example of arc-continent collision in the modern oceans, and compares closely with the Early Ordovician accretion of the Lough Nafooey arc of Connemara, Ireland, to the passive margin of Laurentia. We propose a general model for steady-state arc-continent collision in which arc crust is progressively added to a passive margin during a process of compression, metamorphism and magmatism lasting 3–10 Ma at any one location on the margin. Depending on the obliquity of the angle of collision, the timing of active collision may be diachronous and long-lived along the margin. Magmatism accompanying accretion can be more enriched in incompatible trace elements than average continental crust, contrasting with more depleted magmatism prior to collision. Accretion of a mixture of depleted and enriched arc lithologies to the continental margin allows the continental crust to grow through time by arc-passive margin collision events. During the collision the upper and middle arc crust are detached from the depleted ultramafic lower crust, which is subducted along with the mantle lithosphere on which the arc was founded. Rapid (2–3 Ma) exhumation and gravitational collapse of the collisional orogen forms the Okinawa and South Mayo Troughs in Taiwan and western Ireland, respectively. These basins are filled by detritus eroded from the adjacent collision zone. During subsequent subduction polarity reversal, continuous tearing and retreat of the oceanic lithosphere along the former continent-ocean transition provides space for the new subducting oceanic plate to descend without need for breaking of the original slab.