{"title":"Hydrogen loss from pyroxene within granulite xenoliths at Damaping, North China craton","authors":"","doi":"10.1016/j.jseaes.2024.106331","DOIUrl":null,"url":null,"abstract":"<div><div>The preservation of original water contents within nominally anhydrous minerals is essential for understanding the deep Earth’s water budget. Here we present a comprehensive analysis of mineral chemistry and Fourier transform infrared spectroscopy on 15 lower-crustal granulite xenoliths collected from Damaping in the North China craton. Our analyses reveal that the orthopyroxene grains from two samples exhibit hydrogen-deficient rims, suggestive of hydrogen loss. Drawing upon experimentally determined hydrogen diffusivity in pyroxene, we propose that clinopyroxene, despite the absence of evident hydrogen zoning, may have likewise undergone partial hydrogen depletion. Our findings call into question the conventional belief that hydrogen concentrations in pyroxene are faithful proxies for the original water content in the continental lower crust. We attribute the loss of hydrogen in pyroxene to magmatic outgassing, most likely occurring during the surface flow stage. Such a process could partially explain the relatively lower water contents documented in the granulite xenoliths when compared to those found in the Precambrian granulite terranes from the North China craton. Considering recent studies on mantle xenoliths, it becomes evident that both basalt-hosted mantle and lower-crustal xenoliths may have experienced partial loss of their original water contents within the deep Earth.</div></div>","PeriodicalId":50253,"journal":{"name":"Journal of Asian Earth Sciences","volume":null,"pages":null},"PeriodicalIF":2.7000,"publicationDate":"2024-09-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Journal of Asian Earth Sciences","FirstCategoryId":"89","ListUrlMain":"https://www.sciencedirect.com/science/article/pii/S1367912024003262","RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q2","JCRName":"GEOSCIENCES, MULTIDISCIPLINARY","Score":null,"Total":0}
引用次数: 0
Abstract
The preservation of original water contents within nominally anhydrous minerals is essential for understanding the deep Earth’s water budget. Here we present a comprehensive analysis of mineral chemistry and Fourier transform infrared spectroscopy on 15 lower-crustal granulite xenoliths collected from Damaping in the North China craton. Our analyses reveal that the orthopyroxene grains from two samples exhibit hydrogen-deficient rims, suggestive of hydrogen loss. Drawing upon experimentally determined hydrogen diffusivity in pyroxene, we propose that clinopyroxene, despite the absence of evident hydrogen zoning, may have likewise undergone partial hydrogen depletion. Our findings call into question the conventional belief that hydrogen concentrations in pyroxene are faithful proxies for the original water content in the continental lower crust. We attribute the loss of hydrogen in pyroxene to magmatic outgassing, most likely occurring during the surface flow stage. Such a process could partially explain the relatively lower water contents documented in the granulite xenoliths when compared to those found in the Precambrian granulite terranes from the North China craton. Considering recent studies on mantle xenoliths, it becomes evident that both basalt-hosted mantle and lower-crustal xenoliths may have experienced partial loss of their original water contents within the deep Earth.
期刊介绍:
Journal of Asian Earth Sciences has an open access mirror journal Journal of Asian Earth Sciences: X, sharing the same aims and scope, editorial team, submission system and rigorous peer review.
The Journal of Asian Earth Sciences is an international interdisciplinary journal devoted to all aspects of research related to the solid Earth Sciences of Asia. The Journal publishes high quality, peer-reviewed scientific papers on the regional geology, tectonics, geochemistry and geophysics of Asia. It will be devoted primarily to research papers but short communications relating to new developments of broad interest, reviews and book reviews will also be included. Papers must have international appeal and should present work of more than local significance.
The scope includes deep processes of the Asian continent and its adjacent oceans; seismology and earthquakes; orogeny, magmatism, metamorphism and volcanism; growth, deformation and destruction of the Asian crust; crust-mantle interaction; evolution of life (early life, biostratigraphy, biogeography and mass-extinction); fluids, fluxes and reservoirs of mineral and energy resources; surface processes (weathering, erosion, transport and deposition of sediments) and resulting geomorphology; and the response of the Earth to global climate change as viewed within the Asian continent and surrounding oceans.