Miami heat cs condition zero walkthrough11/9/2022 ![]() Recent photos of well-documented Guaymas Basin hydrothermal sediments and microbial mats have accompanied published papers in online Supplementary Material ( Holler et al., 2011 McKay et al., 2012), sometimes in edited form to show the location of temperature measurements ( McKay et al., 2012), or they have appeared as small-scale figure inserts to illustrate sampling site context ( Callac et al., 2013 MacGregor et al., 2013b). Benthic communities and microbial mats revealing off-axis hydrothermal influence on the sedimented ridge flanks of Guaymas Basin were recorded by deep tow color photography ( Lizarralde et al., 2011). ![]() Color images of hydrothermally active sediments with microbial mats and Riftia colonies were taken from HOV Alvin, and showed the distinct white, yellow, and orange coloration of the microbial mats, dominated by large filamentous sulfur-oxidizing bacteria, at that time ascribed to the genus Beggiatoa ( Jannasch et al., 1989 Gundersen et al., 1992). The black and white photographs published in these early surveys permitted the first glimpses of the Guaymas Basin hydrothermal vent environment. The complex hydrothermal features at the Guaymas Basin seafloor were previously mapped and to a limited extent photographically documented, using a combination of dives with research submersible HOV Alvin, deep tow sonar records, and deep tow thermistor measurements ( Koski et al., 1985 Lonsdale and Becker, 1985 Peter and Scott, 1988). This subsurface processing system produces a maze of subsurface flow pathways that ultimately reach the sediment surface, where they are evident in hydrothermal edifices of different developmental stages, hydrothermal mineral deposits, venting orifices emitting hot hydrothermal fluids, and hydrothermally active sediments. Hydrothermal reactions generate and mobilize volatile hydrocarbons that migrate to the sediment surface ( Peter et al., 1991 Lizarralde et al., 2011), under spatiotemporally variable temperature regimes that may limit or favor biological oxidation and assimilation ( Biddle et al., 2012 McKay et al., 2012). The conspicuous diversity of these seafloor features reflects different geochemical and temperature settings their hydrothermal reactions, driven by underlying thermodynamic disequilibria, are modulated by location-specific reaction pathways in deep sediments or volcanic sills, and the variable residence times of hydrothermal liquid following these reaction pathways and hydrothermal circulation patterns ( Gieskes et al., 1982 Kastner, 1982). Active hydrothermalism is predominantly found in the southern trough, where the hydrothermal sediments, mounds and chimneys form a complex hydrothermal landscape on the seafloor ( Lonsdale and Becker, 1985). The two (northern and southern) axial troughs of Guaymas Basin are bounded by extensive systems of axial-parallel fault lines on both sides ( Lonsdale and Becker, 1985 Fisher and Becker, 1991). ![]() ![]() ![]() Organic-rich fluids transported to the upper sediment column provide fossil carbon substrates to highly active, benthic microbial communities that oxidize and assimilate them ( Pearson et al., 2005 Kniemeyer et al., 2007 Teske et al., 2014). These magmatic intrusions into sediments produce organically derived thermogenic alteration products dominated by methane ( Whelan et al., 1988), CO 2, low-molecular weight organic acids ( Martens, 1990), ammonia ( Von Damm et al., 1985), and a wide spectrum of hydrocarbons ( Simoneit and Lonsdale, 1982 Simoneit, 1985 Bazylinski et al., 1988 Whelan et al., 1988) that are released into sedimentary pore fluid and the ocean. Organic-rich sediments of several hundred meters thickness overlie the spreading centers of Guaymas Basin and alternate with shallow intrusions of doleritic sills into the unconsolidated sediments ( Einsele et al., 1980 Saunders et al., 1982). The Guaymas Basin in the Gulf of California is a young marginal rift basin characterized by active seafloor spreading and rapid deposition of organic-rich, diatomaceous sediments from highly productive overlying waters ( Calvert, 1966). ![]()
0 Comments
Leave a Reply.AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |