Acid Mine Drainage as Energizing Microbial Niches for the Formation of Iron Stromatolites: The Tintillo River in Southwest Spain
Creators: name: Chacon, Elizabeth
name: Santos, Ana
name: Miguel Sarmiento, Aguasanta
name: Luís, Maria Teresa
name: santisteban, María
name: Fortes Garrido, Juan Carlos
name: Dávila Martín, José Miguel
name: DIAZ CURIEL, JESUS MARIA
name: Grande Gil, José Antonio
Publisher: name: Zenodo
Year: 2021
Subjects: Mineralization, Microbe–mineral interactions, Biosignatures, Geomicrobiology, Mars, Extremophiles, Acidophiles, Extreme environments

description:  This study presents a biosedimentological characterization of clastic iron stromatolites found in the Tintillo River, which is affected by AMD. These stromatolites appear as laminated terraced iron formations and represent the most distinctive sedimentary facies in the river. They are formed through the interaction of abiotic fluvial factors and biological zonation, with the authigenic precipitation of schwertmannite and jarosite resulting from microbial-mineral interactions.The Tintillo iron stromatolites consist of bacterial filaments and diatoms, Although AMD systems pose hazards due to various physical, chemical, and biological agents, they also offer biogeochemical insights that can help infer past geochemical conditions on Earth and guide future exploration efforts on extraterrestrial surfaces. As modern automated exploration of extraterrestrial surfaces relies on the morphological identification of biosignatures, a macroscopic characterization of these extreme sedimentary environments is essential for understanding the properties of life.
description: The Iberian Pyrite Belt in southwest Spain hosts some of the largest and diverse extreme acidic environmentswith textural variation across rapidly changing biogeochemical gradients at multiple scales. After almost threedecades of studies, mostly focused on molecular evolution and metagenomics, there is an increasing awarenessof the multidisciplinary potential of these types of settings, especially for astrobiology. Since modern automatizedexploration on extraterrestrial surfaces is essentially based on the morphological recognition of biosignatures,a macroscopic characterization of such sedimentary extreme environments and how they look iscrucial to identify life properties, but it is a perspective that most molecular approaches frequently miss.Although acid mine drainage (AMD) systems are toxic and contaminated, they offer at the same time thebioengineering tools for natural remediation strategies. This work presents a biosedimentological characterizationof the clastic iron stromatolites in the Tintillo river. They occur as laminated terraced iron formations thatare the most distinctive sedimentary facies at the Tintillo river, which is polluted by AMD. Iron stromatolitesoriginate from fluvial abiotic factors that interact with biological zonation. The authigenic precipitation ofschwertmannite and jarosite results from microbial–mineral interactions between mineral and organic matrices.The Tintillo iron stromatolites are composed of bacterial filaments and diatoms as Nitzschia aurariae, Pinnulariaaljustrelica, Stauroneis kriegeri, and Fragilaria sp. Furthermore, the active biosorption and bioleaching of sulfurare suggested by the black and white coloration of microbial filaments inside stromatolites. AMD systems arehazardous due to physical, chemical, and biological agents, but they also provide biogeochemical sources withwhich to infer past geochemical conditions on Earth and inform exploration efforts on extraterrestrial surfaces inthe future.