ABSTRACT

The Triassic Calcare Rosso limestone, in the Southern Alps, was deposited in a semi-arid peritidal environment. Intervals of subaerial exposure produced repeated tepeeization by mudcracking, and the sediments were occasionally flushed by storm tides of hypersaline brines. These alternated with episodes of solution by fresh water and cavern formation. The rocks are a bizarre mixture of pisolitic, fenestral mother rock, with cavity fillings of inwashed marine sediment and red terrigenous slit. The fluctuating chemical environment produced paleospeleothems of aragonite flowstone; large aragonite ray-crystals (raggioni) often 10 cm long; aragonite hemispheres and cement crusts; fibrous, length-slow "coconut-meat" calcite; and cavities filled with white, twisted baroque dolomite. Diageneti history was exceedingly complex, with alternations of hypersaline and fresh water, vadose vs. phreatic episodes, and periods of solution alternating with precipitation.