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| DOI | 10.1029/2023JB028463 |
| The Timescale and Carbon Flux Recorded by Skarn Garnet From Gangdese Arc, Southern Tibet | |
| 发表日期 | 2024 |
| ISSN | 2169-9313 |
| EISSN | 2169-9356 |
| 起始页码 | 129 |
| 结束页码 | 3 |
| 卷号 | 129期号:3 |
| 英文摘要 | Contact metamorphism of carbonate rocks in response to fluid infiltration releases carbon dioxide (CO2), potentially affecting Earth's carbon budget over geological timescales. This process was notably active in the Cretaceous when the closure of the Neo-Tethys Ocean led to extensive arc magmatism in southern Tibet, coincident with a greenhouse climate interval. These arc plutons intersected carbonate sequences and formed widespread calcsilicate rocks. The mineral assemblages of these rocks record both the progression and duration of the CO2 release. In this study, we focus on a representative aureole in southern Tibet that was metamorphosed by a similar to 64 Ma granitoid pluton of the Gangdese Batholith. The aureole presents lithologic zonation, with the inner garnet-wollastonite zone indicating equilibrium with a water-rich fluid at similar to 525 degrees C. Large garnet porphyroblasts feature cross-cutting veins of secondary garnets that illustrate several stages of interface-coupled dissolution-reprecipitation processes facilitated by fluid infiltration. Diffusion modeling for Mg concentration profiles across vein-host garnet yields a brief high-temperature stage (25-150 kyr)-a duration still significantly overestimated considering factors that may accelerate diffusion in garnet, such as lattice parameters and hydration. Such short timescale aligns with conduction modeling of a cooling pluton, which, combined with the bulk-rock mass balance analysis, indicates a local carbon flux comparable to fluxes at other modern tectonic settings. The metamorphic decarbonation, potentially episodic, in the continental arc may have been an important endogenic carbon source in the late Cretaceous. Arc magma reacting with carbonate rocks creates calcsilicate rocks and releases carbon dioxide (CO2) to the atmosphere. The reaction is achieved by the infiltration of magmatic fluids to carbonate rocks. In the Earth's history, warm climates often coincided with extensive arc magmatism, highlighting large CO2 release. By studying the fluid infiltration patterns, chemical, and mineralogical information preserved in the calcsilicate rocks, geologists can understand how much and how fast carbon dioxide is released. The fluid-rock reactions can occur rapidly. Traditional geological dating tools may be difficult to resolve the short timescale of such reactions. When a fluid vein cut across a host mineral, a sharp concentration profile forms between the fluid and the host mineral. The degree to which the sharp profile is smoothed is dependent on time. By using this approach, we quantified the fluid-rock interaction timescale by studying the fluid infiltration patterns in a garnet from southern Tibet. Combined with the amount of CO2 loss, the carbon flux (CO2 loss/time) is large. This study provides field-based evidence on the timescale and magnitude of carbon release from magma-carbonate rock interaction. A 64-million-year felsic intrusion into carbonate rocks in southern Tibet induced the formation of a calcsilicate aureole Skarn garnet reveals interface-coupled dissolution-reprecipitation patterns, driven by shorted-lived fluid infiltrations Over 95% decarbonation over tens of thousands of years corresponds to annual carbon emissions on a teramole scale across the aureole |
| 英文关键词 | carbon flux; calcsilicate; Gangdese arc; garnet; timescale |
| 语种 | 英语 |
| WOS研究方向 | Geochemistry & Geophysics |
| WOS类目 | Geochemistry & Geophysics |
| WOS记录号 | WOS:001176487400001 |
| 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/286884 |
| 作者单位 | University of Toronto |
| 推荐引用方式 GB/T 7714 | . The Timescale and Carbon Flux Recorded by Skarn Garnet From Gangdese Arc, Southern Tibet[J],2024,129(3). |
| APA | (2024).The Timescale and Carbon Flux Recorded by Skarn Garnet From Gangdese Arc, Southern Tibet.JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH,129(3). |
| MLA | "The Timescale and Carbon Flux Recorded by Skarn Garnet From Gangdese Arc, Southern Tibet".JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH 129.3(2024). |
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