Siliciclastic micro- stromatolites in a sandstone cave: role of trapping and binding of detrital particles in formation of cave deposits

The article deals with finely laminated microstromatolites composed of detrital siliciclastic particles, mainly quartz, feldspars and clay minerals, lining the walls of W Sopotni Wielkiej Cave (Polish Outer Carpa- thians). Newly precipitated mineral phases do not contribute to their growth. The microstromatolites cover vertical and overhanging walls of the cave. They form subhorizontal ripples and tongue-shaped stepped microterracettes. The stromatolites are constructed by bacteria and Actinomycetes. Seven morphotypes of micro-organisms have been distinguished. Trapping and binding of detrital particles result in the microstromatolite growth. The growth is influenced by the relatively close distance to the soil cover which provides detrital mineral particles and by the presence of gravitationally widened fissures which guide the water transporting mineral particles down to the cave. The particles are transported only during wet periods. The episodic supply of the particles results in visible lamination of microstromatolites. The microterracettes form in zones of increased water-flow. The lack of auto- chthonous components most probably reflects too low saturation of water to precipitate any minerals.