Lithology, mineral assemblages and microbial fingerprints of the evaporite-carbonate sediments of the coastal sabkha of Abu Dhabi and their extraterrestrial implications

Abstract

Deep-core and surface samples collected from the coastal sabkha of Abu Dhabi were subjected to a multi-proxy study, including petrographic, geochemical and spectroscopic analyses. The sediments studied are composed of biochemical carbonate-evaporite mineral suites, such as calcite, dolomite, aragonite and gypsum, as well as clastic minerals, such as quartz, feldspar and serpentine. These sediments were also strongly influenced by microbial activities as reflected by the presence of cyanobacterial mats, boring, gas bubble structures, pustular and other macro and micro textures. A combination of marine, fluvial, aeolian, and groundwater processes shaped the geomorphology of the area and led to the formation of such mineral suites, as well as their microbial contents. Data collected from Mars indicate that its surface regolith contains sandstone composed of siliciclastic basaltic debris, as well as carbonate (e.g. magnesite) and evaporite (e.g. jarosite and relics of gypsum) mineral assemblages. Additional data suggest the presence of geomorphic features, characteristic of an arid climate, such as sand dunes and desert varnish. The hydrological model for the Late Noachian-Hesperian period of the plant proposed the existence of a surficial layer containing endolithic and stromatolitic cyanobacterial lamina. The combination of the coastal sabkha of Abu Dhabi with its carbonate-evaporite mineral suites, the neighbouring sand dune fields of the Empty Quarter Desert and the basaltic sediments resulted from weathering the ophiolitic Northern Oman Mountains to form a candidate terrestrial geologic province that may explain the mineral association of Mars and its potential biosignatures. The lithological features and the mineral association of the sabkha can be recognized by the present day detection equipment used on Mars, and even if their biosignatures are degraded, their existence may be inferred from these features. Copyright © Cambridge University Press 2010.