K.E. Miller , D.I. Foustoukos , G.D. Cody , C.M. O’D. Alexander
{"title":"在土卫六内部条件下对复杂有机物进行实验加热,支持对大气中N2和CH4的贡献","authors":"K.E. Miller , D.I. Foustoukos , G.D. Cody , C.M. O’D. Alexander","doi":"10.1016/j.gca.2024.12.026","DOIUrl":null,"url":null,"abstract":"<div><div>Titan’s abundant atmospheric N<sub>2</sub> and CH<sub>4</sub> gases are notable characteristics of the moon that may help constrain its origin and evolution. Previous work suggests that atmospheric CH<sub>4</sub> is lost on geologically short timescales and may be replenished from an interior source. Isotopic and noble gas constraints indicate that N<sub>2</sub> may derive from a mixture of NH<sub>3</sub> ice and heating of organic matter. Here, we report experimental results from hydrothermal alteration of insoluble organic matter from the Murchison meteorite and analog insoluble organic matter at temperatures and pressures that are relevant to Titan’s interior. Our results indicate both CH<sub>4</sub> and CO<sub>2</sub> are formed, with the ratio between the two depending on a multitude of factors, particularly temperature and, to a lesser degree, the dielectric constant of water and carbonyl abundance in the starting material. Sufficient CH<sub>4</sub> is produced to source Titan’s atmospheric reservoir if temperatures are greater than 250 °C. Nitrogen is volatilized, primarily in the form of NH<sub>3</sub>, in sufficient abundances to source at least 50 % of Titan’s atmospheric N<sub>2</sub>. The isotopic characteristics of volatilized material relative to the starting organics are consistent with current constraints for the nature of the accreted complex organics and Titan’s evolved atmosphere.</div></div>","PeriodicalId":327,"journal":{"name":"Geochimica et Cosmochimica Acta","volume":"390 ","pages":"Pages 38-56"},"PeriodicalIF":4.5000,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":"{\"title\":\"Experimental heating of complex organic matter at Titan’s interior conditions supports contributions to atmospheric N2 and CH4\",\"authors\":\"K.E. Miller , D.I. Foustoukos , G.D. Cody , C.M. O’D. Alexander\",\"doi\":\"10.1016/j.gca.2024.12.026\",\"DOIUrl\":null,\"url\":null,\"abstract\":\"<div><div>Titan’s abundant atmospheric N<sub>2</sub> and CH<sub>4</sub> gases are notable characteristics of the moon that may help constrain its origin and evolution. Previous work suggests that atmospheric CH<sub>4</sub> is lost on geologically short timescales and may be replenished from an interior source. Isotopic and noble gas constraints indicate that N<sub>2</sub> may derive from a mixture of NH<sub>3</sub> ice and heating of organic matter. Here, we report experimental results from hydrothermal alteration of insoluble organic matter from the Murchison meteorite and analog insoluble organic matter at temperatures and pressures that are relevant to Titan’s interior. Our results indicate both CH<sub>4</sub> and CO<sub>2</sub> are formed, with the ratio between the two depending on a multitude of factors, particularly temperature and, to a lesser degree, the dielectric constant of water and carbonyl abundance in the starting material. Sufficient CH<sub>4</sub> is produced to source Titan’s atmospheric reservoir if temperatures are greater than 250 °C. Nitrogen is volatilized, primarily in the form of NH<sub>3</sub>, in sufficient abundances to source at least 50 % of Titan’s atmospheric N<sub>2</sub>. The isotopic characteristics of volatilized material relative to the starting organics are consistent with current constraints for the nature of the accreted complex organics and Titan’s evolved atmosphere.</div></div>\",\"PeriodicalId\":327,\"journal\":{\"name\":\"Geochimica et Cosmochimica Acta\",\"volume\":\"390 \",\"pages\":\"Pages 38-56\"},\"PeriodicalIF\":4.5000,\"publicationDate\":\"2025-02-01\",\"publicationTypes\":\"Journal Article\",\"fieldsOfStudy\":null,\"isOpenAccess\":false,\"openAccessPdf\":\"\",\"citationCount\":\"0\",\"resultStr\":null,\"platform\":\"Semanticscholar\",\"paperid\":null,\"PeriodicalName\":\"Geochimica et Cosmochimica Acta\",\"FirstCategoryId\":\"89\",\"ListUrlMain\":\"https://www.sciencedirect.com/science/article/pii/S001670372400677X\",\"RegionNum\":1,\"RegionCategory\":\"地球科学\",\"ArticlePicture\":[],\"TitleCN\":null,\"AbstractTextCN\":null,\"PMCID\":null,\"EPubDate\":\"\",\"PubModel\":\"\",\"JCR\":\"Q1\",\"JCRName\":\"GEOCHEMISTRY & GEOPHYSICS\",\"Score\":null,\"Total\":0}","platform":"Semanticscholar","paperid":null,"PeriodicalName":"Geochimica et Cosmochimica Acta","FirstCategoryId":"89","ListUrlMain":"https://www.sciencedirect.com/science/article/pii/S001670372400677X","RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q1","JCRName":"GEOCHEMISTRY & GEOPHYSICS","Score":null,"Total":0}
Experimental heating of complex organic matter at Titan’s interior conditions supports contributions to atmospheric N2 and CH4
Titan’s abundant atmospheric N2 and CH4 gases are notable characteristics of the moon that may help constrain its origin and evolution. Previous work suggests that atmospheric CH4 is lost on geologically short timescales and may be replenished from an interior source. Isotopic and noble gas constraints indicate that N2 may derive from a mixture of NH3 ice and heating of organic matter. Here, we report experimental results from hydrothermal alteration of insoluble organic matter from the Murchison meteorite and analog insoluble organic matter at temperatures and pressures that are relevant to Titan’s interior. Our results indicate both CH4 and CO2 are formed, with the ratio between the two depending on a multitude of factors, particularly temperature and, to a lesser degree, the dielectric constant of water and carbonyl abundance in the starting material. Sufficient CH4 is produced to source Titan’s atmospheric reservoir if temperatures are greater than 250 °C. Nitrogen is volatilized, primarily in the form of NH3, in sufficient abundances to source at least 50 % of Titan’s atmospheric N2. The isotopic characteristics of volatilized material relative to the starting organics are consistent with current constraints for the nature of the accreted complex organics and Titan’s evolved atmosphere.
期刊介绍:
Geochimica et Cosmochimica Acta publishes research papers in a wide range of subjects in terrestrial geochemistry, meteoritics, and planetary geochemistry. The scope of the journal includes:
1). Physical chemistry of gases, aqueous solutions, glasses, and crystalline solids
2). Igneous and metamorphic petrology
3). Chemical processes in the atmosphere, hydrosphere, biosphere, and lithosphere of the Earth
4). Organic geochemistry
5). Isotope geochemistry
6). Meteoritics and meteorite impacts
7). Lunar science; and
8). Planetary geochemistry.