Trench retreat recorded by a subduction zone metamorphic history

Upper amphibolite-facies metamorphism in subduction zone rocks may occur under exceptional tectonic settings. Differentiating competing mechanisms for its occurrence requires carefully integrated, high-resolution thermobarometric and geochronologic studies of melange rocks with well-defined field re...

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Bibliographic Details
Published in:Geology (Boulder) 2022-11, Vol.50 (11), p.1281-1286
Main Authors: Dong Jie, Dong Jie, Grove, Marty, Wei Chunjing, Wei Chunjing, Han Baofu, Han Baofu, Yin, An, Chen Jiafu, Chen Jiafu, Li Ang, Li Ang, Zhang Zhicheng, Zhang Zhicheng
Format: Article
Language:English
Subjects:
absolute age
Amphibolites
California
Catalina Schist
Channel Islands
chemical composition
Chronostratigraphy
Cretaceous
Decompression
Eclogite
Garnet
Geochronology
Geology
High temperature
History
igneous and metamorphic rocks
Isotopes
Los Angeles County California
Mesozoic
metals
metamorphic rocks
Metamorphism
Metamorphism (geology)
mineral composition
nesosilicates
orthosilicates
oxides
P-T-t paths
petrography
Petrology
rare earths
Rocks
rutile
Santa Catalina Island
Schist
Schists
Sedimentary facies
silicates
Subduction
Subduction (geology)
Subduction zones
Tectonics
Temperature
U/Pb
United States
zircon
zircon group
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Summary:Upper amphibolite-facies metamorphism in subduction zone rocks may occur under exceptional tectonic settings. Differentiating competing mechanisms for its occurrence requires carefully integrated, high-resolution thermobarometric and geochronologic studies of melange rocks with well-defined field relationships. We present new pressure, temperature, and age data from the classic Cretaceous Catalina Schist in southern California (USA) that allow us to establish a plausible model for its high-temperature metamorphic history. Our results indicate that garnet-amphibolite blocks in the structurally highest amphibolite-facies melange preserve evidence of three stages of tectonic evolution: (1) prograde lawsonite eclogite-facies metamorphism that peaked at 2.4-2.7 GPa with temperatures >580°C during fixed-trench subduction (120-115 Ma); (2) post-peak epidote eclogite-facies metamorphism followed by amphibolite-facies metamorphism at 1.4-1.3 GPa with temperatures of 740-790°C during trench retreat (115-105 Ma); and (3) isothermal decompression (1.3 GPa to
ISSN:0091-7613
1943-2682
DOI:10.1130/G50385.1