Strain modes within the forearc, arc and back-arc domains in the Izu (Japan) and Taiwan arc-continent collisional settings

详细信息    查看全文

• 作者：Serge Lallemand ^{lallem@gm.univ-montp2.fr" class="auth_mail}
• 关键词：Arc-continent collision ; Middle crust ; Intra-oceanic slivering ; Mantle decoupling ; Forearc subduction ; Luzon arc ; IBM arc
• 刊名：Journal of Asian Earth Sciences
• 出版年：1 June, 2014
• 年：2014
• 卷：86
• 期：Complete
• 页码：1-11
• 全文大小：4608 K

文摘

In this study, I examine the strain modes of the forearc, arc and back-arc domains in arc-continent collisional settings leading to arc material subduction, delamination and/or accretion. The study focusses on two well-documented colliding island arcs: the Izu-Bonin-Mariana (IBM) arc in Japan and the Luzon arc in Taiwan, both carried by the Philippine Sea plate. Firstly, there is a body of evidence that both the IBM and the Luzon arcs were built on the same Late Jurassic to Early Cretaceous 鈥減roto-Philippine Sea Plate鈥?crust. Their internal structure is thus more heterogeneous than expected from Paleogene or Neogene supposedly 鈥渋ntra-oceanic鈥?island arcs. Secondly, those arc systems and proximal 鈥渂ack-arcs鈥?have similar seismic characteristics attesting either for the presence of a middle crust with continental velocities and/or serpentinized uppermost mantle that facilitate crustal shortening/slivering and subsequent decoupling from the rest of the subducting plate. It is shown that the proximal back-arc domain (called 鈥渞ear-arc鈥?in case of paleoarc activity), overlying the mantle wedge and the subducting slab, may lose its strength if slab-derived hydration occur. Decoupling then occurs below the Moho. Arc delamination likely occurs in mid-crustal levels because middle-crust, heated by nearby magmatism, becomes weak. Accretion of arc material onto the upper plate depends on the characteristics of the arc itself and the geodynamic configuration. Most of the accreted material is probably underplated rather than frontally accreted.