Forearc serpentinite m¨¦lange from the Hongseong suture, South Korea

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• 作者：Sung Won Kim^a ; M. Santosh^b ; Nari Park^c ; Sanghoon Kwon^c ;   ; ^{skwon@yonsei.ac.kr}
• 关键词：Dismembered serpentinite mé ; lange ; Hydrated forearc mantle peridotite ; Chromian spinel ; Zircon SHRIMP ; Wolhyeonri complex ; Korean Peninsula
• 刊名：Gondwana Research
• 出版年：2011
• 出版时间：November 2011
• 年：2011
• 卷：20
• 期：4
• 页码：852-864
• 全文大小：3313 K

文摘

The signature of a prolonged subduction¨Caccretion history from Paleozoic to Early Mesozoic is preserved within the dismembered serpentinite m¨¦langes within the Hongseong suture. Here we present major and trace element data from the mafic fragments/blocks within the Baekdong serpentinite m¨¦lange revealing their arc-like tholeiite affinity within a suprasubduction zone tectonic setting. Chromian spinel compositions from the Baekdong hydrated mantle peridotite (serpentinite) are characterized by high Cr# (0.53?.67) and Fe²⁺/Fe³⁺ ratio, medium Mg# (0.42?.55), and Al₂O₃ contents (17?5 wt. % ) indicating a forearc tectonic environment for the hydrated mantle peridotite. The estimated melting degree (> 17.6 % ) and FeO/MgO of the parental melt (0.9?.3) are consistent with that of forearc magmas. SHRIMP zircon U¨CPb ages from a high-grade mafic rock and an anorthosite from the study area give protolith ages of ~ 310 Ma and ~ 228 Ma, respectively. Zircons from an associated orthogneiss block within the m¨¦lange yield a Neoproterozoic crystallization age of ~ 748 Ma. These results, together with the recent SHRIMP zircon ages from other dismembered serpentinite m¨¦langes within the Wolhyeonri complex, suggest that Paleozoic to Early Mesozoic subduction and subsequent collision events led to the exhumation of the hydrated forearc mantle peridotites from a metasomatized mantle wedge. The Hongseong region preserves important clues to a long-lived subduction system related to global events associated with the final amalgamation of the Pangaea supercontinent.