Abstract: In Lake Salda (Southwestern, Türkiye), modern microbialites containing hydrated Mg carbonates continueto form on the shoreline of the lake and at 15 m water depth in structures ranging from a few cm in size to about10 m in height with 3-4 m width. For the first time, these organo-sedimentary structures were classified and their morphotypes, sedimentological and textural characteristics along with their spatial distribution in the lake were identified. In this context, 5 different zones were identified in the lake. In the lake, stromatolitic thrombolites are themost dominant microbialite type, while stromatolites and thrombolites are restricted to certain parts of the lake. Stromatolitic thrombolites have a wide variety of morphologies, usually dome-shaped and cauliflower-like, while they are rarely tabular. On a meso-scale (cm), stromatolitic thrombolites exhibit finger-shaped (2-5 cm) laminatedmini-columns, and dendritic, and bulbous growth structures. Thrombolites with cauliflower morphology coalesce to form a large reef-like structure at depth (10-20 m). Thrombolites with stromatolitic laminae and dendritic internalstructure are limited to certain zones in the lake (Zone 2, 3). The macro-scale external morphology of the microbialitesis shaped primarily by the influence of the prevailing environmental conditions. Seasonal fluctuations in lake waterlevel, regional differences in sedimentation rates, prevailing winds and currents are the main factors controlling the depositional environment. The internal growth structure of microbialites depends on the microbial community structure and the conditions of the depositional environment. Mineralogical study of the microbial layer revealed adifferent hydrated Mg carbonate mineral, dypingite (Mg5(CO3)4. OH2.5H2O), for the first time. This mineral, closely related to extracellular polymeric matter (EPS), is the precursor of hydromagnesite. Petrographic investigations ofthe microbialites revealed the presence of abundant vertical and near-vertical filament (mineralised`)-like structures associated with carbonates, exhibiting a clotted texture containing peloids of various sizes in addition to a thin lamination. Nodular aragonites are generally associated with microbial layers, while fibres developed in void sand aragonite fans and isopach fringes formed by their aggregation indicate secondary and abiotic carbonate precipitation in the lake. Due to their structural, mineralogical and compositional diversity, Lake Salda microbialites are a potential modern analogue that may reveal the origin and formation processes of both Mg-carbonates inthe geological record and hydrated Mg-carbonates detected in a possible palaeolake in Jezero crater, one of the Martian craters. In this study, new data on Lake Salda microbialites is evaluated in terms of their origin, formation mechanism and potential for biosignatures.