Lipids in Hydrothermal Sulfide Ores from the 9°50′N Field of the East Pacific Rise

摘要

The 9°50′N hydrothermal field of the East Pacific Rise (EPR) formed in April 1991 after the eruption of an underwater volcano in an area formerly occupied by active hydrothermal fields. The biological community that had developed in these fields was buried under basaltic lava. Observations from the manned submersible Alvin carried out less than two weeks after the eruption showed that fissures in basaltic lava emit diffuse hot fluids, which stimulate the formation of spacious fields covered by light microbe mats around these vents. After one year, sulfide plates and edifices up to 5 m high already existed within the 9°50′N field. Moreover, its biological community included both microorganisms and vestimentifers. Three years later, the community also included mollusks and other animals. One can assume that frequent volcanic eruptions within axial parts of high-rate spreading ridges promoted the burial of many hydrothermal fields together with their biological communities. Fissured lava flows provide favorable conditions for the mixing of cold seawater with hydrothermal fluids and the formation of the so-called subseafloor biosphere in this zone. Many researchers assume wide distribution of the "deep oceanic biosphere" (DOB). The 9°49′-9°51′N EPR area demonstrates several features indirectly suggesting the existence of the subseafloor biosphere. For example, the activity of microorganisms populating this area substantially changes the composition of gas components in hydrothermal solutions.