Morphological and mineralogical characterization of speleothems from the Chimalacatepec lava tube system, Central Mexico

Abstract

Abstract:Siliceous, opal-A speleothems of the Chimalacatepec lava tube system in central Mexico are characterized here for the first time. Morphologically, they can be classified into cylindrical and planar, and display a wide array of shapes, inner textures, and locations within the lava tube. All speleothems analyzed here are composed of opal-A, and their pores are filled with calcite and monohydrocalcite. Microscopic examination reveals a variety of microbial-looking, silicified filaments and cell casts embedded within the micro lamination of the structures. The abundance of biofilms in the Chimalacatepec lava tube may share similarities with other volcanic caves elsewhere. The direct presence of such bimorphs in the microstructure of the speleothems suggests the biological mediation of these structures. Potential mechanisms include nucleation and sorption of silica on extracellular polymeric substances in the biofilms that, along with the SiO 2 saturation in the water film and evaporative effects, result in the formation of a speleothem. That said, the presence of microbes in these and other cave systems, or their inevitable interactions with the mineral phase of the speleothems, should not be surprising. In view of this, these structures can be most accurately described as biospeleothems. This study contributes to our understanding of the diversity of such structures in these types of cave systems and our ability to recognize the presence of microbes in these.lava tubes, siliceous speleothems, Chichinautzin, biospeleothems

Organic geochemistry and mineralogy suggest anthropogenic impact in speleothem chemistry from volcanic show caves of the Galapagos

“…Some vibrational bands linked to calcite were also reported by FTIR and Raman ( Figures S3 B and S4 B and Table S1 ). Carbonate-siliceous coralloid speleothems, with alternating layers showing different mineralogical composition, were also reported in lava tubes ( López-Martínez et al., 2016 ; Miller et al., 2014 ), limestone caves ( Suchý et al., 2021 ) and granite cavities ( Vidal-Romaní et al., 2010 ). This mineralogical intercalation during speleothem growth may occur because of changes on surface environmental conditions or land use, or to internal factors within the cave, such as changes in pH, in the chemical composition of the dripping water or adaption works of the cave to tourism accessibility ( Miller et al., 2016 , 2018 ; 2020a ).…”

Microbial signatures from speleothems: A petrographic and scanning electron microscopy study of coralloids from the Koněprusy Caves (the Bohemian Karst, Czech Republic)

“…The presence of irregular, several millimetrethick laminae and voids filled with microbe-rich silica that occur inside carbonate speleothems is another noteworthy aspect of the Kon eprusy coralloids. Various siliceous, mostly opaline, speleothems containing microorganisms have already been reported, mainly from volcanic caves and evacuated lava tubes (Forti, 2001(Forti, , 2005Daza & Bustillo, 2014;Miller et al, 2014;L opez-Mart ınez et al, 2016), caves in granitic rocks (e.g. Vidal Roman ı et al, 2010) and some sandstone caves (e.g.…”

“…Ercole et al, 2001;Cacchio et al, 2004;Pacton et al, 2013;Shtober-Zisu et al, 2014; see also ; Barton, 2006;Barton & Jurado, 2007;Jones, 2010;and Dhami et al, 2018, for reviews). Microorganisms have been shown to be important active and passive promoters of mostly redox chemical reactions that influence the precipitation of many cave minerals, including calcite, silica, ferromanganese deposits and some sulphur-containing mineral species (Castanier et al, 1999;Forti, 2001;Jones, 2001;Engel et al, 2004;Barton, 2006;Lozano & Rossi, 2012;Daza & Bustillo, 2014;L opez-Mart ınez et al, 2016). Also, some types of specific secondary cave deposits like moonmilk, cave pisoliths, pool fingers, residual ferromanganese deposits, helictites, and some stalactites and stalagmites that have, for a long time, been tacitly assumed to be purely inorganic products, have since been re-evaluated as being mediated by various microbial communities (Northup et al, 2000;Forti, 2001; Barton et al, 2001;Spilde et al, 2005;Barton & Northup, 2007;Cacchio et al, 2012;Tisato et al, 2015;Melim et al, 2016;Jung et al, 2017).…”

“…For speleothems containing evidence of microbial life such as filaments, hyphae, or mineralized biofilms, the new terms 'biothems' (e.g. Cunningham et al, 1995;Queen & Melim, 2006) or 'biospeleothems' (Aubrecht et al, 2008;L opez-Mart ınez et al, 2016) have even been introduced. Various microbemineral interactions that take place in cave environments have been recognized as sources of inspiring cross-disciplinary information providing applications in civil and environmental engineering, drug development, metallogeny and astrobiology (Boston et al, 2001;Tisato et al, 2015;L opez-Mart ınez et al, 2016;Dhami et al, 2018;Gong et al, 2020).…”

Multitechnique characterization of secondary minerals near HI-SEAS, Hawaii, as Martian subsurface analogues

“…The formation of crystalline crusts made of gypsum and opal/calcite coralloid speleothems occurs in the lava tubes where water is observed on the walls, ceilings, cracks; or where water is dripping from lava stalactites. These secondary minerals, encompassing calcite, silica speleothems, gypsum, and thenardite, commonly originate as a consequence of seepage waters infiltrating the lava tube system, dissolving minerals in the process 6 , 16 . As these waters undergo transformations within the lava tube’s unique environmental conditions, such as shifts in pressure, temperature, or evaporation levels, they become supersaturated, prompting the minerals to precipitate and gradually shape the distinctive features found in the lava tubes 16 .…”