Speleogenesi e speleotemi di opale della Cueva Guacamaya, Auyan Tepui, Gran Sabana, Venezuela

In March 2009 the Guacamaya cave was discovered on the Auyan Tepui by the helicopter pilot Raul Arias. It represents one of the longest caves explored on this table mountain, the only one known today with a complete horizontal development, comparable with those of the Brewer Cave System, in the Chimantha Tepui (the world largest sandstone cave). This cave presents typical morphologies, developed along an evident interbed of oxides, amorphous silica and clay interposed between hard quartzitic massive banks. In the walls around this layer, a variety of opal speleothems, of unusual dimensions and shapes, together with gypsum flowers and crusts have been documented. This preliminary study focuses on the general morphology of the cave conduits and on the mineralogical compositions and features of the opal-gypsum speleothems.