气候变化领域集成服务门户(CCPortal): Multiple Episodes of Fluid Infiltration Along a Single Metasomatic Channel in Metacarbonates (Mogok Metamorphic Belt, Myanmar) and Implications for CO2 Release in Orogenic Belts

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DOI	10.1029/2020JB020988
	Multiple Episodes of Fluid Infiltration Along a Single Metasomatic Channel in Metacarbonates (Mogok Metamorphic Belt, Myanmar) and Implications for CO2 Release in Orogenic Belts
	Guo S.; Chu X.; Hermann J.; Chen Y.; Li Q.; Wu F.; Liu C.; Sein K.
发表日期	2021
ISSN	21699313
卷号	126 期号:1
英文摘要	Fluid infiltration into metacarbonates is a key mechanism to induce orogenic decarbonation, which influences the global carbon cycle and long-term climate evolution. Little is known regarding the fluid pathways during episodic infiltration events and how flow patterns control time-integrated CO2 outflux. We investigate the “vein-like” polycrystalline mineral reaction zones (PMRZs) in dolomite marbles (Mogok metamorphic belt, Myanmar), which are formed by metasomatism via the infiltration of Si–Al–K–Ti–Zr-bearing fluids. The petrographic textures and mineral U–Pb chronology reveal three episodes of fluid influx in a single PMRZ: (1) the initial episode (Stage-I) transformed most dolomite into Mg-rich silicates/oxides and calcite at ∼35–36 Ma indicated by baddeleyite cores; (2) baddeleyite rims gave ages of ∼23–24 Ma, representing a subsequent infiltration episode (Stage-II) that modified Stage-I minerals via a dissolution–precipitation mechanism; (3) the final episode (Stage-III) is recorded by zircon replacing baddeleyite, which yielded ages of ∼17 Ma. Stage-III fluid has a higher SiO2 activity and (Formula presented.) [CO2/(CO2 + H2O)] than Stage-I/Stage-II fluids. Thermodynamic and mass-balance analyses indicate that Stage-I infiltration causes >62–67% loss of CO2 by both dolomite-consuming reactions and calcite dissolution, whereas the latter two infiltration episodes induce <12–18% loss of CO2 via calcite dissolution. Our results provide compelling evidence that repeated episodes of infiltration (each separated in time by 7–13 Ma) occurred along a single channel in marbles. The initial infiltration episode may create high-permeability regions, offering favorable channels for later-stage fluids that transfer obviously less CO2 than the initial metasomatism. This considerably complicates a quantitative assessment of CO2 liberation from metacarbonates during orogenesis. © 2020. American Geophysical Union. All Rights Reserved.
英文关键词	Baddeleyite; fluid-mineral equilibria; metamorphic CO2 release; multiple fluid infiltration; orogenic belt; reaction zone
语种	英语
来源期刊	Journal of Geophysical Research: Solid Earth
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/187424
作者单位	State Key Laboratory of Lithospheric Evolution, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing, China; CAS Center for Excellence in Tibetan Plateau Earth Sciences, Beijing, China; Department of Earth Sciences, University of Toronto, Toronto, ON, Canada; Institute of Geological Sciences, University of Bern, Bern, Switzerland; Myanmar Geosciences Society, Hlaing University Campus, Yangon, Myanmar
推荐引用方式 GB/T 7714	Guo S.,Chu X.,Hermann J.,et al. Multiple Episodes of Fluid Infiltration Along a Single Metasomatic Channel in Metacarbonates (Mogok Metamorphic Belt, Myanmar) and Implications for CO2 Release in Orogenic Belts[J],2021,126(1).
APA	Guo S..,Chu X..,Hermann J..,Chen Y..,Li Q..,...&Sein K..(2021).Multiple Episodes of Fluid Infiltration Along a Single Metasomatic Channel in Metacarbonates (Mogok Metamorphic Belt, Myanmar) and Implications for CO2 Release in Orogenic Belts.Journal of Geophysical Research: Solid Earth,126(1).
MLA	Guo S.,et al."Multiple Episodes of Fluid Infiltration Along a Single Metasomatic Channel in Metacarbonates (Mogok Metamorphic Belt, Myanmar) and Implications for CO2 Release in Orogenic Belts".Journal of Geophysical Research: Solid Earth 126.1(2021).