Petrologic perspectives on tectonic evolution of a nascent basin (Okinawa Trough) behind Ryukyu Arc: A review
Petrologic perspectives on tectonic evolution of a nascent basin (Okinawa Trough) behind Ryukyu Arc: A review
复制标题
DOI：
10.1007/s13131-014-0400-2
复制
发表时间：
2014-04
影响因子：
1.4
通讯作者：
Q. Yan;Xuefa Shi
中科院分区：
文献类型：
--
作者：
Q. Yan;Xuefa Shi
冲绳海槽是一个弧后初始边缘海盆，位于琉球弧-海沟系之后。冲绳海槽的形成和演化与晚中新世以来菲律宾海板块向欧亚板块俯冲的过程密切相关。海槽的构造演化与其他活动弧后，如马里亚纳海槽和南部劳盆地，都经历了最初的裂陷和随后的扩张过程相似。本文综合了冲绳海槽、琉球弧和菲律宾海板块的基性火山熔岩的岩石学和地球化学资料，结合地球物理资料，探讨了菲律宾海板块-琉球弧-冲绳海槽系（PROS）俯冲源区（输入）与弧或弧后岩浆（输出）之间的关系。结果表明，冲绳海槽熔岩的成因主要由欧亚板块下的陆下岩石圈地幔、印度洋中脊玄武岩（MORB）型地幔和太平洋MORB型地幔组成。具有印度MORB型地幔特征的俯冲组分中的浅部含水流体和深部含水熔体加入到岩浆源区中，改变了琉球原始地幔楔和冲绳海槽的陆下岩石圈地幔（SCLM）。在海槽和弧的东北端，太平洋MORB型地幔取代了印度MORB型地幔，成为岩浆源区的主导。沿着琉球弧和冲绳海槽走向，微量元素比值和同位素组成的系统变化反映了俯冲作用对岩浆源区的一级影响。综合岩石学资料和地球物理资料，认为冲绳海槽正经历西南段的“海底扩张”过程、中段的“裂谷扩展”过程和东北段的“地壳伸展”过程，西南段发育新生洋盆。
Okinawa Trough is a back-arc, initial marginal sea basin, located behind the Ryukyu Arc-Trench System. The formation and evolution of the Okinawa Trough is intimately related to the subduction process of the Philippine Sea Plate beneath the Eurasian Plate since the late Miocene. The tectonic evolution of the trough is similar to other active back-arcs, such as the Mariana Trough and southern Lau Basin, all of which are experiencing the initial rifting and subsequent spreading process. This study reviews all petrologic and geochemical data of mafic volcanic lavas from the Okinawa Trough, Ryukyu Arc, and Philippine Sea Plate, combined with geophysical data to indicate the relationship between the subduction sources (input) and arc or back-arc magmas (output) in the Philippine Sea Plate-Ryukyu Arc-Okinawa Trough system (PROS). The results obtained showed that several components were variably involved in the petrogenesis of the Okinawa Trough lavas: sub-continental lithospheric mantle underlying the Eurasian Plate, Indian mid-oceanic ridge basalt (MORB)-type mantle, and Pacific MORB-type mantle. The addition of shallow aqueous fluids and deep hydrous melts from subducted components with the characteristics of Indian MORB-type mantle into the mantle source of lavas variably modifies the primitive mantle wedge beneath the Ryukyu and subcontinental lithospheric mantle (SCLM) beneath the Okinawa Trough. In the northeastern end of the trough and arc, instead of Indian MORB-type mantle, Pacific MORB-type mantle dominates the magma source. Along the strike of the Ryukyu Arc and Okinawa Trough, the systematic variations in trace element ratios and isotopic compositions reflect the first-order effect of variable subduction input on the magma source. In general, petrologic data, combined with geophysical data, imply that the Okinawa Trough is experiencing the “seafloor spreading” process in the southwest segment, “rift propagation” process in the middle segment, and “crustal extension” process in the northeast segment, and a nascent ocean basin occurs in the southwest segment.