Volcanic speleothems are cave formations found in lava tubes that are composed of minerals that have been deposited by volcanic activity. Siliceous speleothems are important to determine the timing and intensity of past volcanic eruptions, as well as assessing the environment conditions [1]. Another important contribution is the identification of biosignatures (organic compounds or microorganisms) preserved within the speleothems, which is relevant for astrobiology. However, for that, it is required the use of increasingly cutting-edge analytical molecular characterization techniques with the goal to analyze a remarkable number of different organic compounds. One of the most promising techniques is analytical pyrolysis coupled to ultra-high resolution mass spectrometry (Py-GC/Q-TOF). This advanced technique allows the analyze of more than 15,000 different organic compounds per sample, without any pre-treatment. However, this overwhelming number is not feasible to study each organic compound individually. Therefore, it is mandatory the development of novel graphical-statistical tools to help identifying their main biogenic families [2], as well as the alterations and adaptation of microorganisms to environmental (e.g., climate change, drought) or anthropogenic (e.g., oil spills, forest fires) factors [3,4]. In this communication, it will present the advantages of the combination of ultra-high resolution analytical pyrolysis technique and chemometrics as an innovative strategy for unsupervised classification and visual analysis of organic matrices preserved in siliceous speleothems. References: [1] Miller, A.Z., et al., Journal of Chromatography A 1461 (2016) 144-152. [2] Jiménez-Morillo, N.T., et al., Science of the Total Environment 817 (2022) 152957. [3] Miller, A.Z., et al., Science of the Total Environment 698 (2020) 134321. [4] Miller, A.Z., et al., IScience 25 (2022) 104556.

Comunicación oral presentada en el 1st European Meeting on Geomicrobiology of volcanic caves. días 2-3 de marzo de 2023 celebrado en la Casa de la Ciencia-CSIC de Sevilla

This work received support from the Portuguese Foundation for Science and Technology (FCT) under the MICROCENO project (PTDC/CTA-AMB/0608/2020).

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