Tapices microbianos y estructuras sedimentarias asociadas en sistemas deposicionales evaporíticos de La Manchaun enfoque actualista

Abstract

Microorganisms in microbial mats interact with the environment leading to specific sedimentary structures (microbially induced sedimentary structures - MISS) that differ either from purely abiotic structures or from those typical of stromatolites. Although microbial mats are common in modern evaporitic environments, references to this type of structures formed under hypersaline conditions are scarce. In this paper, a variety of sedimentary structures associated with microbial mats in salt lakes (Lillo, Toledo) are described. In addition to a number of bioinduced precipitated minerals, the structures are varied and include irregular growth forms of the microbial mats, biolamination, traces of gas bubbling, trapping and doming, desiccation polygonal forms usually associated with gas bubbles and showing curling up edges, and wrinkle structures, pseudo-ripples and other shapes resembling elephant skin (old elephant skin), ripple patches, mat chips, fenestral fabrics, etc. Some of these structures are well represented in Tertiary evaporitic series, thus indicating that they have potential for preservation in rock record and points to reconsidering earlier interpretations of these evaporitic sequences. The new observations can increase knowledge on the biological origin of the microbially induced sedimentary structures and provide new criteria for their interpretation.