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

Journal article


Publication Details

Author(s): Li J, Klemd R, Gao J, John T
Journal: Journal of Petrology
Publication year: 2016
Volume: 57
Journal issue: 1
Pages range: 119-146
ISSN: 0022-3530
Language: English


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.


FAU Authors / FAU Editors

Klemd, Reiner Prof. Dr.
Professur für Geochemie und Lagerstättenkunde
Li, Jilei
Professur für Geochemie und Lagerstättenkunde


External institutions with authors

Chinese Academy of Sciences (CAS) / 中国科学院
Freie Universität Berlin


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.

BibTeX: 

Last updated on 2019-06-06 at 22:10