气候变化领域集成服务门户(CCPortal): Miocene olivine leucitites in southern Tibet: Implications for the recycling of carbonates into the mantle during continental subduction

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DOI	10.1016/j.chemgeo.2023.121835
	Miocene olivine leucitites in southern Tibet: Implications for the recycling of carbonates into the mantle during continental subduction
	Lei, Ming; Lustrino, Michele; Xu, Jifeng; Kang, Zhiqiang; Guo, Zhengfu; Chen, Jianlin
发表日期	2024
ISSN	0009-2541
EISSN	1872-6836
卷号	644
英文摘要	We present a comprehensive geochronological, mineralogical, and geochemical study on previously unknown olivine leucitites occurring in the Maiga area of southern Tibet to examine the possibility of carbonate recycling during continental subduction. The Miocene (similar to 16 Ma) Maiga olivine leucitites are characterized by low SiO2 (44.6-46.3 wt%), high MgO (14.0-15.7 wt%), and ultra-calcic (CaO/Al2O3 = 1.1-1.2) compositions, along with arc-like incompatible element patterns (e.g., enrichment in large-ion lithophile and light rare earth elements, and depletion in high-field-strength elements). These rocks also have extremely radiogenic Sr-87/Sr-86((i)) (0.715647-0.715844), unradiogenic epsilon Nd-(i) (-11.6 to -11.2) and epsilon Hf-(i) (-10.5 to -10.0), and moderately radiogenic Pb-206/Pb-204((i)) (18.44-18.46) isotopic compositions. The studied samples are also characterized by slightly heavy O isotope ratios (clinopyroxene delta O-18 = +6.7 parts per thousand to +8.7 parts per thousand) and relatively low water contents (0.75-1.75 wt%). The geochemical features of the Maiga olivine leucitites are compatible with an origin from a carbonated peridotite mantle source. Additionally, based on the regional tectonic evolution and mid-ocean-ridge-basalt-like Zn isotopic compositions (delta Zn-66 = +0.26 parts per thousand to +0.30 parts per thousand), we hypothesize these magmas formed from interactions between ambient mantle peridotite and recycled Ca-rich carbonate sediments during Indian continental subduction. The transition from the neighboring Miocene lamproite-like rocks in southern Tibet to olivine leucititic magmas in Maiga is assumed to reflect the tapping of two different mantle sources. The first was modified by silicate-rich sediments, which generated lamproite-like rocks, whereas the Maiga mantle source was modified by carbonate-rich sediments. This study and previous research on other K2O-rich subduction-related magmas indicate that non-negligible amounts of carbonates can be recycled deep into the mantle during continental subduction, which may play an important role in global carbon recycling.
关键词	Olivine leucitite MORB-like Zn isotopes Carbonated peridotite Ca-rich carbonate sediments Continental subduction Southern Tibet
英文关键词	ULTRAPOTASSIC IGNEOUS ROCKS; GEOCHEMICAL CONSTRAINTS; TRACE-ELEMENT; ISOTOPE COMPOSITION; MAFIC MAGMATISM; SW TIBET; LITHOSPHERE; ORIGIN; PETROGENESIS; PYROXENITE
WOS研究方向	Geochemistry & Geophysics
WOS记录号	WOS:001127418400001
来源期刊	CHEMICAL GEOLOGY
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/282725
作者单位	Chinese Academy of Sciences; Guangzhou Institute of Geochemistry, CAS; Sapienza University Rome; Sapienza University Rome; Consiglio Nazionale delle Ricerche (CNR); Istituto di Geologia Ambientale e Geoingegneria (IGAG-CNR); China University of Geosciences - Beijing; Guilin University of Technology; Chinese Academy of Sciences; Institute of Geology & Geophysics, CAS
推荐引用方式 GB/T 7714	Lei, Ming,Lustrino, Michele,Xu, Jifeng,et al. Miocene olivine leucitites in southern Tibet: Implications for the recycling of carbonates into the mantle during continental subduction[J],2024,644.
APA	Lei, Ming,Lustrino, Michele,Xu, Jifeng,Kang, Zhiqiang,Guo, Zhengfu,&Chen, Jianlin.(2024).Miocene olivine leucitites in southern Tibet: Implications for the recycling of carbonates into the mantle during continental subduction.CHEMICAL GEOLOGY,644.
MLA	Lei, Ming,et al."Miocene olivine leucitites in southern Tibet: Implications for the recycling of carbonates into the mantle during continental subduction".CHEMICAL GEOLOGY 644(2024).