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Initiation of modern-style subduction in the Neoarchean; from plume to subduction with frequent slab break-off

Li Dapeng, Chen Yuelong, Xue Guoliang, Kang Huan, Yu Yang, Geng Jianzhen, Zhang Yulong and Li Ting
Initiation of modern-style subduction in the Neoarchean; from plume to subduction with frequent slab break-off
Geological Society of America Bulletin (March 2020) Pre-Issue Publication

Abstract

Fundamental geodynamic changes from vertical tectonics to lateral subduction occurred during the Neoarchean, yet detailed processes related to this transition and initiation of modern-style subduction remain enigmatic. Successive Neoarchean magmatic rocks including both plume-derived komatiites and subduction-related supracrustal and intrusive rocks appeared and preserved key information on the late Archean geodynamic changes in the Western Shandong Province granite-greenstone belt (WSP), North China Craton. In this study, whole-rock geochemical and Sm-Nd isotopic data and zircon U-Pb and Lu-Hf isotopes are reported for early Neoarchean supracrustal and intrusive rocks for the WSP. Temporally, the early Neoarchean magmatic movements in the WSP can be subdivided into two stages, including the early stage (2.77-2.69 Ga) and the late stage (2.69-2.60 Ga). Spatially, from southwest to northeast, intrusive rocks with similar ages define three belts (A, B, and C). Early stage tholeiitic and enriched meta-basalts were plume-related, representing oceanic crust opening from a pre-early Neoarchean continent. Slab subduction at least initiated at ca. 2.74 Ga and generated various Neoarchean tonalite-trondhjemite-granodiorites, quartz diorites, and arc-related volcanic rocks and mafic intrusions. Episodic emergence of meta-basaltic rocks and/or mafic intrusions with depleted epsilon Hf(t) values and low (La/Yb)N ratios indicates frequent slab break-offs during ca. 2.70-2.68 Ga, 2.66-2.64 Ga, and 2.62-2.60 Ga due to a relatively hotter mantle and regional heating by mantle plume. Secular geochemical changes of mafic and felsic rocks in this study outline roles of slab subduction in contributions of cooling the mantle, secular mantle refertilization, and crustal growth.


ISSN: 0016-7606
EISSN: 1943-2674
Coden: BUGMAF
Serial Title: Geological Society of America Bulletin
Serial Volume: Pre-Issue Publication
Title: Initiation of modern-style subduction in the Neoarchean; from plume to subduction with frequent slab break-off
Affiliation: China University of Geosciences-Beijing, School of Earth Science and Resources, Beijing, China
Published: 20200309
Text Language: English
Publisher: Geological Society of America (GSA), Boulder, CO, United States
References: 82
Accession Number: 2020-028720
Categories: Igneous and metamorphic petrologyGeochronology
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. 1 table, geol. sketch maps
N35°00'00" - N36°30'00", E117°00'00" - E119°00'00"
Secondary Affiliation: Chinese Academy of Sciences, Institute of Remote Sensing and Digital Earth, CHN, ChinaChina Geological Survey-Tianjin Center, CHN, China
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2020, American Geosciences Institute. Reference includes data from GeoScienceWorld, Alexandria, VA, United States. Reference includes data supplied by the Geological Society of America, Boulder, CO, United States
Update Code: 202009
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