The importance of fault control on the geomorphological development of a deep karst system: the case of Sima GESM, a Z-supercave in southern Spain

The mountainous karst massif in the Sierra de las Nieves (southern Spain) and the adjacent large outcrops of subcontinental mantle peridotites provide this area with a distinctive geodiversity that has contributed to the recent declaration of the zone as the new Sierra de las Nieves National Park. In addition, the Alpine tectonic interaction between the peridotites and the carbonate formations originated an important fault, the Turquillas fault, that has conditioned the existence of two tectonic blocks in the karst massif, one uplifted with respect to the other. Also, in the uplifted block, the fault has contributed to the generation of Z-supercaves, which are defined in this paper as caves with more than 1000 m of development in the vertical or Z dimension. Sima GESM with 1100 m of depth is the only Z-supercave known in the giant geologic structure of the Gibraltar Arc, which speaks on the infrequent and exceptionality of the generation of these underground geomorphological systems. The task of this paper is to present a detailed study of the Turquillas fault and its influence in the surface and underground geomorphology and hydrogeology and in particular its influence and implications in the development of the deep karst system defined as the Z-supercave. It is hoped that this study will contribute to identify the necessary conditions for the development of these extraordinary geomorphic systems which are of great international relevance in the major mountain ranges of the world with high relief karst and deep karst systems.