Geomorphological and sedimentary features of an underwater lava tube: the Túnel de la Atlántida (Lanzarote, Spain)

The Túnel de la Atlántida (Atlantida Tunnel), located in Lanzarote Island (Canary Islands, Spain), with a length of about 2000 m and a depth of 64 m, is the largest submerged lava tunnel in the world. It corresponds to the submerged part of the lava tube complex of the La Corona volcano, with a length of about 10 km. During the development of the Sublantida Project, using diving techniques, various forms associated with the formation of the volcanic tube have been catalogued and a study of its sediments, minerals and speleothems has been carried out, including XRD, ESEM and petrological microscopy. It has been possible to propose a paleoenvironmental reconstruction from the formation of the volcanic tube, ca.21 Ka ago, to the present. The geomorphological, petrological, and sedimentary characteristics associated with the formation of the lava tube justify its importance as a World Geological Site of Interest.Acknowledgments: This project has received funding from the Spanish Ministry of Science and Innovation and the Spanish State Research Agency (grants CGL2017-91218-EXP and PID2019-110603RB-I00-SUBSYST). It is a contribution to the IGCP Project 725.