Geology, morphology and mineralogy of sulfide-carbonate hydrothermal-bacterial structures on the surface of Tessel paleovolcano lava (south coast of Crimea)

Abstract

   Research subject. Sulfide-carbonate hydrothermal-bacterial structures on the surface of Tessel paleovolcano lava.   Materials and methods. The structures under study were found during detailed geological works. Petrographic thin sections were studied using an Olympus Bx5 microscope. Carbonate and sulfide samples were examined using an RZMMA-202M scanning electron microscope.   Results. For the first time, the contacts of the studied structures with their enclosing siltstones and mudstones were described. The structures are of tubular and flat shapes. In terms of mineral composition, the structures exhibit three zones: central, lateral and that of bacterial overgrowth. The middle part of the central zone features a fluid channel with inclusions of quartz, barite, nakrite, galena, chalcopyrite, pyrrhotite, sphalerite, pyrite, shells of largefauna, ash and tuff material. Spherulites and microtubular carbonate formations testify to the participation of bacterial and archaean communities in the construction process. The study of carbonates and sulfides confirmed the use of deep fluids by prokaryotes.   Conclusion. The main role in the formation of the sulfide-carbonate hydrothermal-bacterial structures under study belonged to the community of prokaryotes and fluids from the depths. The external morphology of the studied structures along with the presence of mineralogical zonality, a fluid channel, oil products, and oases of life with a large fauna indicate the similarity of their formation conditions to those of sulfide-carbonate smokers of the Piip volcano. Some differences in the mineral composition are associated with different depths and fluids of their formation.