DOI: 10.1016/j.earscirev.2020.103448
论文题名: Magmatic responses to Cretaceous subduction and tearing of the paleo-Pacific Plate in SE China: An overview
作者: Guo F. ; Wu Y. ; Zhang B. ; Zhang X. ; Zhao L. ; Liao J.
刊名: Earth Science Reviews
ISSN: 00128252
出版年: 2021
卷: 212 语种: 英语
中文关键词: Arc-type mafic rocks
; Cretaceous
; Intraplate basalts
; Paleo-Pacific subduction
; SE China
; Slab tearing
英文关键词: basalt
; computer simulation
; continental arc
; Cretaceous
; deformation mechanism
; intraplate process
; magmatism
; mantle source
; numerical model
; ocean island basalt
; Pacific plate
; plate motion
; plate tectonics
; subduction
; subduction zone
; China
英文摘要: Both Cretaceous arc-type and intraplate rocks are widely distributed in SE China, in association with subduction of the paleo-Pacific Plate. However, it remains unclear whether there exists a genetic link between the intraplate and subduction-related magmatism. Here we conduct a comprehensive geochemical data compilation, sorting and processing of the Cretaceous mafic igneous rocks from SE China, in combination with a 2-D numerical simulation on slab melting, to further decipher the petrogenetic relationship between the arc-type and intraplate magmatism under a unified tectonic framework invoking subduction and rollback-tearing of the paleo-Pacific Ocean. The Cretaceous arc-type mafic rocks (120–80 Ma) include eruptive and intrusive rocks, distributing along the coastal region in a NE-NNE direction. After parent magma compositional recalculation of the mafic intrusions, the results indicate that both the eruptive and intrusive arc-type mafic rocks are hydrous calc-alkaline basalts, with enrichments in large ion lithophile elements (LILEs) and light rare earth elements (LREEs) but depletions in high field strength elements (HFSEs), crust-like Sr-Nd-Pb-Hf isotopic compositions, and low Lu/Hf ratios. All these features are typical of igneous rocks formed in a continental arc. The combined data suggest their mantle source was mainly metasomatized by melts derived from the subducted terrestrial sediments and reflect a relatively hot subduction zone during Cretaceous. The intraplate mafic rocks (110–70 Ma) distribute in SE China interior and generally show trace element geochemistry similar to oceanic island basalt (OIB, hereafter we term them as OIB-like basalts). They can be further divided into two groups: high-Nb (Nb > 50 ppm) and low-Nb (Nb < 40 ppm) basalts. The high-Nb basalts have depleted asthenospheric mantle-like isotopic compositions. Their mantle source was composed mainly of pyroxenite that was likely formed through interaction between the asthenosphere and melts from the dehydrated subducted slab. Relative to the high-Nb basalts, the low-Nb basalts have lower Nb/REE and Nb/LILE ratios, and more evolved but highly variable isotopic compositions. Their mantle source was also the asthenosphere metasomatized by addition of the slab melts containing a higher proportion of recycled sediment component. From the arc-type to low-Nb and ultimately to high-Nb mafic rocks, increases of Nb, Nb/LILE and Nb/REE ratios are coupled with more depleted Sr-Nd-Pb-Hf isotopic features, reflecting the occurrence of melting from the upper subducted sediment to the lower oceanic mafic crust that had experienced extensive dehydration. Further thermodynamic modelling results show that melting of the dehydrated slab can occur along the torn surface and lower part of the oceanic crust, once the slab is strongly thinned and fractured in response to tearing and fragmentation. In combination with the contemporaneous sedimentary records in SE China, the Cretaceous mafic magmatism provided geochemical records of tectonic transition from early Cretaceous advanced subduction to late Cretaceous rollback of the paleo-Pacific slab, during which slab tearing or fragmentation and the resultant melting of the dehydrated subducted slab acted as a predominant agent for mantle enrichment. © 2020 Elsevier B.V. Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/166412
Appears in Collections: 气候变化与战略
There are no files associated with this item.
作者单位: State Key Laboratory of Isotope Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou, 510640, China; Innovation Academy for Earth Science, CAS, Beijing, 100029, China; School of Earth Sciences and Engineering, Sun Yat-Sen University, Guangzhou, 510275, China; College of Earth and Planetary Sciences, University of Chinese Academy of Sciences, Beijing, 100049, China
Recommended Citation:
Guo F.,Wu Y.,Zhang B.,et al. Magmatic responses to Cretaceous subduction and tearing of the paleo-Pacific Plate in SE China: An overview[J]. Earth Science Reviews,2021-01-01,212