A preliminary study of magmatic and hydrothermal Ni-Cu-Fe-Co sulfides in basic rocks of the external zone of the Betic Cordillera

Abstract

More than 2,000 outcrops of igneous mafic rocks with ages spanning from Triassic to Cretaceous are widespread in the internal and external zones of the Betic Cordillera. This magmatism originated by continental rifting associated to the break-up of the Pangea continent in the Late Permian-Triassic, and subsequent aperture of the Atlantic Ocean from the Jurassic to the Cretaceous (Morata et al., 1997). It comprises submarine basaltic flows plus small subvolcanic dolerite bodies, whose compositions changed from picritic-tholeiitic at the beginning of the Upper Triassic to transitional and alkaline sodic throughout the Jurassic, continuing intermittently until the Upper Cretaceous (Morata et al., 1997). These mafic rocks had significant economic value as industrial material for infrastructure construction and building decoration. More recently, they have been of great interest as resource for the critical raw material graphite from a world’s unique sulfur-graphite mineralization near the locality of Huelma in the Jaén province (Luque del Villar et al., 2009). Other styles of mineralization associated to this mafic magmatism include skarn-related Fe-ores from the localities of Garcíez in the Jaén province, and Baena in the Córdoba province (Fenoll & García-Rosell, 1975), and those from the Coto Minero de Cehegín in the Murcia province (GarcíaCervigón et al., 1976). The latter ores from Murcia were exploited until 1989 for Fe and are currently under evaluation by the company Solid Mines España to resume Fe mining. Despite these efforts, to date, there are no comprehensive studies regarding the metallogenic potential for economic metals such as Ni, Cu and Co, which are known to selective concentrate in these types of parental basaltic magmas. In particular, the mineralogy of these metals is still unknown.