community to study the biodiversity of this poorly explored extreme environment. The correlation of the operational taxonomic units (OTUs)s presence with physicochemical variables showed that the system contains three distinct environments: the crater lagoon, the Upper Río Agrio, and the Salto del Agrio waterfall, a point located approximately 12 km down the origin of the river, after it emerges from the Caviahue lake. The prokaryotic community of the Copahue Volcano-Río Agrio system is mainly formed by acidic bacteria and archaea, such as Acidithiobacillus, Ferroplasma, and Leptospirillum, which have been isolated from similar environments around the world. These results support the idea of a ubiquitous acidic biodiversity; however, this highly interesting extreme environment also has apparently autochthonous species such as Sulfuriferula, Acidibacillus Alicyclobacillus Acidianus copahuensis, and strains of and .

Love, G.D., Zumberge, J.A., Cárdenas, P., Sperling, E.A., Rohrssen, M., Grosjean, E., Grotzinger, J.P., Summons, R.E., 2020. Sources of C steroid biomarkers in Neoproterozoic - Cambrian rocks and oils. Nature Ecology & 30 Evolution 4, 34-36.

https://doi.org/10.1038/s41559-019-1048-2 Original Article: Nettersheim, B.J., Brocks, J.J., Schwelm, A., Hope, J.M., Not, F., Lomas, M., Schmidt, C., Schiebel, R., Nowack, E.C.M., De Deckker, P., Pawlowski, J., Bowser, S.S., Bobrovskiy, I., Zonneveld, K., Kucera, M., Stuhr, M., Hallmann, C., 2019. Putative sponge biomarkers in unicellular Rhizaria question an early rise of animals. Nature Ecology &Evolution 3, 577-581. Reply to Comment: Hallmann, C., Nettersheim, B.J., Brocks, J.J., Schwelm, A., Hope, J.M., Not, F., Lomas, M., Schmidt, C., Schiebel, R., Nowack, E.C.M., De Deckker, P., Pawlowski, J., Bowser, S.S., Bobrovskiy, I., Zonneveld, K., Kucera, M., Stuhr, M., 2020. Reply to: Sources of C30 steroid biomarkers in Neoproterozoic - Cambrian rocks and oils. Nature Ecology &Evolution 4, 37-39.

Lowe, D.R., Bishop, J.L., Loizeau, D., Wray, J.J., Beyer, R.A., 2019. Deposition of >3.7 Ga clay-rich strata of the Mawrth Vallis Group, Mars, in lacustrine, alluvial, and aeolian environments. GSA Bulletin 132, 17-30.

https://doi.org/10.1130/B35185.1 The presence of abundant phyllosilicate minerals in Noachian (>3.7 Ga) rocks on Mars has been taken as evidence that liquid water was stable at or near the surface early in martian history. This study investigates some of these clay-rich strata exposed in crater rim and inverted terrain settings in the Mawrth Vallis region of Mars. In Muara crater the 200-m-thick, clay-rich Mawrth Vallis Group (MVG) is subdivided into five informal units numbered 1 (base) to 5 (top). Unit 1 consists of interbedded sedimentary and volcanic or volcaniclastic units showing weak Fe/Mg-smectite alteration deposited in a range of subaerial depositional settings. Above a major unconformity eroded on Unit 1, the dark-toned sediments of Unit 2 and lower Unit 3 are inferred to represent mainly wind-blown sand. These are widely interlayered with and draped by thin layers of light-toned sediment representing fine suspended-load aeolian silt and clay. These sediments show extensive Fe/Mg- smectite alteration, probably reflecting subaerial weathering. Upper Unit 3 and units 4 and 5 are composed of well-layered, fine-grained sediment dominated by Al-phyllosilicates, kaolinite, and hydrated silica. Deposition occurred in a large lake or arm of a martian sea. In the inverted terrain 100 km to the NE, Unit 4 shows very young slope failures suggesting that the clay-rich sediments today retain a significant component of water ice. The MVGprovides evidence for the presence of large, persistent standing bodies of water on early Mars as well as a complex association of flanking shoreline, alluvial, and aeolian systems. Some of the clays, especially the Fe/Mg smectites in upper units 1 and 2 appear to have formed through subaerial weathering whereas the aluminosilicates, kaolinite, and hydrated silica of units 3, 4, and 5 formed mainly through alteration of fine sediment in subaqueous environments.

Lowry, D., Fisher, R.E., France, J.L., Coleman, M., Lanoisellé, M., Zazzeri, G., Nisbet, E.G., Shaw, J.T., Allen, G., Pitt, J., Ward, R.S., 2020. Environmental baseline monitoring for shale gas development in the UK: Identification and geochemical characterisation of local source emissions of methane to atmosphere. Science of The Total Environment 708, 134600.