Looking for biosignatures in a pristine Mars analogue environment on Earth

• Main Authors: Palma, Vera, Jiménez Morillo, N. T., Sauro, Francesco, Massironi, M., Rosa Arranz, José M. de la, González-Pérez, José Antonio, Onac, Bogdan P., Tiago, I., Caldeira, Ana Teresa, Miller, A. Z.
• Other Authors: Portuguese Foundation for Science and Technology (FCT), Ministerio de Ciencia e Innovación (España), Agencia Estatal de Investigación (España)
• Format: Conference Object
• Language: English
• Published: European Geosciences Union 2023
• Subjects: North Atlantic
• Online Access: http://hdl.handle.net/10261/357679; https://doi.org/10.5194/egusphere-egu23-6149; https://doi.org/10.13039/501100004837; https://doi.org/10.13039/501100011033

Resumen de la comunicación oral presentada en EGU23, the 25th EGU General Assembly, held 23-28 April, 2023 in Vienna, Austria and Online. Online at https://egu23.eu/, id. EGU-6149 The Selvagens Islands (Madeira, Portugal), located in the North Atlantic, are a small archipelago of volcanic origin formed by two main islands, which emerged in the Oligocene (25-29 Ma). These oceanic islands are recognized as a unique example of marine and terrestrial biodiversity, characterized by many endemic species. Still unblemished by civilization, this isolated and undisturbed ecosystem makes the volcanic caves from Selvagens a promising model system for investigating biosignatures preserved in the rock record valuable for astrobiology. The Inferno Cave, one of the three main terrestrial caves of the Selvagens Islands, has copious amounts of fine white powder crusts scattered throughout the cave. From the mineralogical point of view, the whitish powdery deposits are mainly composed of gypsum and minor amounts of clay minerals. Thermal analyses (TG/DTG-DsC) revealed the presence of labile and stable organic matter (OM), with contrasting relative abundances among the gypsum samples. The stable isotope composition of carbon was determined by elemental analysis coupled to isotope ratio mass spectrometry (EA/IRMS) to decipher the origin of the organic fraction preserved in the gypsum deposits. Two well-differentiated organic matter pools were distinguished: one comprising ????13C values > –19 ‰ related to microbial activity (i.e., microbial degradation of fresh organic matter), and another with ????13C < –20 ‰), which may suggest the preservation of recalcitrant biomarkers from aboveground vegetation. U-series results from the gypsum deposits were used to produce isochron ages needed to generate an age-depth model for the 1-m thick gypsum deposit. A detailed study of the organic fraction preserved in the gypsum deposits was conducted by pyrolysis gas chromatography/ mass spectrometry (Py-GC/MS) and by GC-MS after extraction of ...