Imawarì Yeuta: a new giant cave system in the quartz sandstones of the Auyan Tepui, Bolivar state, Venezuela

In February 2013 a new huge cave system in quartz-sandstones has been discovered in the eastern sector of the Auyan Tepui, Venezuela by an Italian-Venezuelan team (La Venta Esplorazioni Geografiche and Teraphosa Exploring Team). In twelve days of exploration over 15 km of passages were surveyed and other 4 km were explored. The system has nine entrances and hosts three rivers giving rise to three resurgences. The cave passages belong to two levels, an active one in which the rivers flow with a general and gradual WNW trend, and a inactive level located from 4 to 20 metres higher with a N-S direction. The active levels are lithologically controlled whith typical pillars, potholes and wide and rounded bedrock channels with very scarce sediment fill. The inactive level instead hosts large quantities of secondary minerals, mainly sulphates-phosphates, and very nice and rare opal and silica speleothems. Flowing, drip and standing waters have been analysed in situ for their Si content and many morphological observations have been carried out in order to try and understand the speleogenesis of such large quartzite caves. Further geological, mineralogical, geomicrobiological and biological studies are required in this exceptionally interesting quartzite cave.