Slab rollback and microcontinent subduction in the evolution of the Zambales Ophiolite Complex(Philippines):A review  

作　　者：Graciano P.Yumul Jr. Carla B.Dimalanta Ricky C.Salapare Karlo L.Queano Decibel V.Faustino-Eslava Edanjarlo J.Marquez Noelynna T.Ramos Betchaida D.Payot Juan Miguel R.Guotana Jillian Aira S.Gabo-Ratio Leo T.Armada Jenielyn T.Padrones Keisuke Ishida Shigeyuki Suzuki 

机构地区：[1]Apex Mining Company Inc.,Ortigas,Pasig City,Philippines [2]Rushurgent Working Group,National Institute of Geological Sciences,College of Science,University of the Philippines,Diliman,Quezon City,Philippines [3]GHD,Chino Roces Avenue,Makati City,Philippines [4]Department of Environmental Science,Ateneo de Manila University,Quezon City,Philippines [5]School of Environmental Science and Management,University of the Philippines-Los Baños,Laguna,Philippines [6]Department of Physical Sciences and Mathematics,University of the Philippines-Manila,Padre Faura,Manila,Philippines [7]Graduate School of Natural Science and Technology,Kanazawa University,Japan [8]Institute of Renewable Natural Resources,University of the Philippines-Los Baños,Laguna,Philippines [9]Institute of Socio-Arts and Sciences,University of Tokushima,Tokushima,Japan [10]Department of Earth Sciences,Okayama University,Okayama,Japan

出　　处：《Geoscience Frontiers》2020年第1期23-36,共14页地学前缘（英文版）

基　　金：support from the University of the PhilippinesNational Institute of Geological Sciences;financial support from the Department of Science and Technology through the years

摘　　要：New radiolarian ages show that the island arc-related Acoje block of the Zambales Ophiolite Complex is possibly of Late Jurassic to Early Cretaceous age.Radiometric dating of its plutonic and volcanichypabyssal rocks yielded middle Eocene ages.On the other hand,the paleontological dating of the sedimentary carapace of the transitional mid-ocean ridge-island arc affiliated Coto block of the ophiolite complex,together with isotopic age datings of its dikes and mafic cumulate rocks,also yielded Eocene ages.This offers the possibility that the Zambales Ophiolite Complex could have:(1)evolved from a Mesozoic arc(Acoje block)that split to form a Cenozoic back-arc basin(Coto block),(2)through faulting,structurally juxtaposed a Mesozoic oceanic crust with a younger Cenozoic lithospheric fragment or(3)through the interplay of slab rollback,slab break-off and,at a later time,collision with a microcontinent fragment,caused the formation of an island arc-related ophiolite block(Acoje)that migrated trench-ward resulting into the generation of a back-arc basin(Coto block)with a limited subduction signature.This Meso-Cenozoic ophiolite complex is compared with the other oceanic lithosphere fragments along the western seaboard of the Philippines in the context of their evolution in terms of their recognized environments of generation.New radiolarian ages show that the island arc-related Acoje block of the Zambales Ophiolite Complex is possibly of Late Jurassic to Early Cretaceous age.Radiometric dating of its plutonic and volcanichypabyssal rocks yielded middle Eocene ages.On the other hand,the paleontological dating of the sedimentary carapace of the transitional mid-ocean ridge-island arc affiliated Coto block of the ophiolite complex,together with isotopic age datings of its dikes and mafic cumulate rocks,also yielded Eocene ages.This offers the possibility that the Zambales Ophiolite Complex could have:(1) evolved from a Mesozoic arc(Acoje block) that split to form a Cenozoic back-arc basin(Coto block),(2) through faulting,structurally juxtaposed a Mesozoic oceanic crust with a younger Cenozoic lithospheric fragment or(3) through the interplay of slab rollback,slab break-off and,at a later time,collision with a microcontinent fragment,caused the formation of an island arc-related ophiolite block(Acoje) that migrated trench-ward resulting into the generation of a back-arc basin(Coto block) with a limited subduction signature.This Meso-Cenozoic ophiolite complex is compared with the other oceanic lithosphere fragments along the western seaboard of the Philippines in the context of their evolution in terms of their recognized environments of generation.

关 键 词：OPHIOLITE Slab rollback RADIOLARIANS SUBDUCTION Zambales Philippines 

分 类 号：P587[天文地球—岩石学] P542[天文地球—地质学]