2026https://www.datacommons.psu.edu/The Pennsylvania State UniversityFunding Source: This material is based upon work supported by NASA Habitable Worlds grant 80NSSC24M0210.publication date2026ISO 19115 Topic CategoriesgeoscientificinformationHydrocarbons, methane, ethane, biosignatures, carbon isotope, hydrogen isotopeNone.The University excludes any and all implied warranties, including warranties or merchantability and fitness for a particular purpose. The University makes no warranty or representation, either express or implied, with respect to the FILES or accompanying documentation, including its quality, performance, merchantability, or fitness for a particular purpose. The FILES and documentation are provided "as is" and the USER assumes the entire risk as to its quality and performance. The University will not be liable for any direct, indirect, special, incidental, or consequential damages arising out of the use or inability to use the FILES or any accompanying documentation. The USER is granted permission to translate and add value to the FILES for the use of the FILES on its computer hardware; provided, however, that the USER annually notify the University of any customizing or value-adding work done.Distinguishing between microbial, abiotic, and thermogenic methane sources is fundamental for understanding Earths carbon cycle and for assessing potential biosignatures beyond our planet. Stable carbon isotopic analyses have long been central to geochemical investigations, and extending such approaches to volatile reservoirs on other Solar System bodies remains a major goal of planetary science. However, whether the carbon isotopic composition of methane can be confidently used as a biosignature remains debated. Over the years, numerous diagnostic diagrams have been developed to infer methane origins based on stable isotope measurements and hydrocarbon compositions, yet unambiguous source identification remains challenging. A key limitation is the strong dependence of existing proxies on the isotopic composition of the initial carbon pool, potentially an unknown parameter in many planetary environments. Here, we compiled a dataset comprising 351 microbial natural samples, 94 microbial laboratory experiments, 615 thermogenic natural samples, 6 thermogenic laboratory experiments, 125 abiotic natural samples, and 52 abiotic laboratory experiments, spanning early and recent studies. We apply the same isotopic and compositional proxies used in conventional approaches but also integrate them into combined parameters, such as the difference in carbon isotopic composition between methane and ethane, which normalize isotope signatures and reduce sensitivity to initial carbon isotopic composition. In the resulting diagnostic diagrams, a Bayes classifier provides a statistical framework that quantifies source probabilities and enables robust discrimination between microbial and abiotic methane. The results suggest hydrocarbon geochemistry can be a transferable and rigorous tool for interpreting methane origins across terrestrial and extraterrestrial environments.Researcher(s):-- O.M. Mcintosh Department of Geosciences, Pennsylvania State University, University Park, PA, USA. C.H. House Department of Geosciences, Pennsylvania State University, University Park, PA, USA.The Pennsylvania State UniversityOphelie Mcintoshmailing and physical address

Department of Geosciences, Pennsylvania State University, University Park, PA, USA.

University ParkPennsylvania16802United Statesomm5285@psu.eduPenn State Data CommonsMetadata Coordinatormailing address

115 Land and Water Building

University ParkPennsylvania16802United States814-865-8792datacommons@psu.eduFGDC Content Standards for Digital Geospatial MetadataFGDC-STD-001-1998local timehttp://www.esri.com/metadata/esriprof80.htmlESRI Metadata Profile20250527125049002025052709440400FGDC CSDGM MetadataTRUELocal Area Network1.01500000005000FGDCPenn State Data Commonsmailing and physical address

115 Land and Water Building

University ParkPennsylvania16802United States(814) 865 - 8792datacommons@psu.eduThe USER shall indemnify, save harmless, and, if requested, defend those parties involved with the development and distribution of this data, their officers, agents, and employees from and against any suits, claims, or actions for injury, death, or property damage arising out of the use of or any defect in the FILES or any accompanying documentation. Those parties involved with the development and distribution excluded any and all implied warranties, including warranties or merchantability and fitness for a particular purpose and makes no warranty or representation, either express or implied, with respect to the FILES or accompanying documentation, including its quality, performance, merchantability, or fitness for a particular purpose. The FILES and documentation are provided "as is" and the USER assumes the entire risk as to its quality and performance. Those parties involved with the development and distribution of this data will not be liable for any direct, indirect, special, incidental, or consequential damages arising out of the use or inability to use the FILES or any accompanying documentation.Penn State Data CommonsMetadata Coordinator814-865-8792115 Land and Water BuildingUniversity ParkPennsylvania16802USdatacommons@psu.eduArcGIS Metadata1.0Penn State Data Commons(814) 865 - 8792115 Land and Water BuildingUniversity ParkPennsylvania16802USdatacommons@psu.eduThe Pennsylvania State UniversityPenn StateUniversity ParkPennsylvania16802USISO 19115 Topic CategoriesThe USER shall indemnify, save harmless, and, if requested, defend those parties involved with the development and distribution of this data, their officers, agents, and employees from and against any suits, claims, or actions for injury, death, or property damage arising out of the use of or any defect in the FILES or any accompanying documentation. Those parties involved with the development and distribution excluded any and all implied warranties, including warranties or merchantability and fitness for a particular purpose and makes no warranty or representation, either express or implied, with respect to the FILES or accompanying documentation, including its quality, performance, merchantability, or fitness for a particular purpose. The FILES and documentation are provided "as is" and the USER assumes the entire risk as to its quality and performance. Those parties involved with the development and distribution of this data will not be liable for any direct, indirect, special, incidental, or consequential damages arising out of the use or inability to use the FILES or any accompanying documentation.The University excludes any and all implied warranties, including warranties or merchantability and fitness for a particular purpose. The University makes no warranty or representation, either express or implied, with respect to the FILES or accompanying documentation, including its quality, performance, merchantability, or fitness for a particular purpose. The FILES and documentation are provided "as is" and the USER assumes the entire risk as to its quality and performance. The University will not be liable for any direct, indirect, special, incidental, or consequential damages arising out of the use or inability to use the FILES or any accompanying documentation. The USER is granted permission to translate and add value to the FILES for the use of the FILES on its computer hardware; provided, however, that the USER annually notify the University of any customizing or value-adding work done.Microsoft Windows 2000 Version 5.0 (Build 2195) Service Pack 4; ESRI ArcCatalog 8.3.0.800publication dateoriginal metadata