Poly-cyclic Metamorphic Evolution of Eclogite: Evidence for Multistage Burial–Exhumation Cycling in a Subduction Channel

Li J, Klemd R, Gao J, John T (2016)

Publication Language: English

Publication Type: Journal article

Publication year: 2016

Journal

Journal of Petrology Oxford University Press (OUP): Policy B - Oxford Open Option A

Book Volume: 57

Pages Range: 119-146

Journal Issue: 1

DOI: 10.1093/petrology/egw002

Abstract

(Ultra-)high-pressure [(U)HP] eclogites provide direct evidence for metamorphic processes at mantle depths in subduction zones. Textural evidence and pressure–temperature ( P – T ) path reconstruction allow a unique opportunity to constrain the geodynamic processes along the plate interface. To better understand the dynamics of subduction channels, we present a detailed petrographical, petrological and pseudosection modeling study of a metamorphically complex HP eclogite sample from a tectonic block of the Akeyazi (U)HP metamorphic terrane in the Chinese Tianshan. Mineral chemical variations and textural discontinuities show that all the major phases of the rock (garnet, epidote, clinopyroxene and amphibole) display multiple growth zones compatible with a poly-cyclic evolution including two burial–exhumation cycles. The precise P – T path derived from thermodynamic modeling based on effective bulk compositions suggests that the eclogite underwent complex burial–exhumation cycles with two P – Tloops indicated by the occurrence of polyphase garnet and mutually replaced and regrown amphibole. It is suggested that the eclogite sample, which represents a relic of tectonically detached oceanic crust, underwent two burial–exhumation cycles during convective flow in a subduction channel. This natural occurrence is consistent with numerical simulation studies showing that pressure cycling is to be expected for deeply subducted oceanic crust in a subduction channel. The modeled exhumation process for the eclogite sample corresponds to a previously suggested subduction channel exhumation model for the Akeyazi (U)HP rocks.

Authors with CRIS profile

Jilei Li Professur für Geochemie von Lagerstätten Reiner Klemd Professur für Geochemie von Lagerstätten

Involved external institutions

Freie Universität Berlin DE Germany (DE) Chinese Academy of Sciences (CAS) / 中国科学院 CN China (CN)

How to cite

APA:

Li, J., Klemd, R., Gao, J., & John, T. (2016). Poly-cyclic Metamorphic Evolution of Eclogite: Evidence for Multistage Burial–Exhumation Cycling in a Subduction Channel. Journal of Petrology, 57(1), 119-146. https://dx.doi.org/10.1093/petrology/egw002

MLA:

Li, Jilei, et al. "Poly-cyclic Metamorphic Evolution of Eclogite: Evidence for Multistage Burial–Exhumation Cycling in a Subduction Channel." Journal of Petrology 57.1 (2016): 119-146.

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