This year, the Barcelona Student Chapter organized a field trip to the Ronda ultramafic massif (Betic Cordillera) as its main activity. The field trip took place 5 th and 6 th of October. The participants were 10 students (bachelor, master and PhD students) from Barcelona Student Chapter (including people from the University of Barcelona and the University of Granada) and the Prague Student Chapter. The field trip was led by Prof. Fernando Gervilla, full professor at the University of Granada, who was accompanied by Dr. José María González- Jiménez, from the University of Granada, and one of our advisors, Dr. Joaquín A. Proenza, from the University of Barcelona.

 

In this field trip, we were able to observe the different lithologies form the ultramafic massif of Ronda and the associated magmatic mineralizations. The lithologies consist mainly of lherzolites and harzburgites with minor dunite and pyroxenite layers. They represent a portion of subcontinental lithospheric mantle tectonically emplaced on Paleozoic metasediments during the Alpine orogeny (20-22 Ma). Three main domains are observed in the peridotites: i) spinel ± garnet tectonic domain, ii) granular peridotite domain, and iii) plagioclase tectonic domain. Regarding the magmatic mineralizations, they are spatially distributed according to the zoning of the massifs. We visited some outcrops of podiform chromitites within refractory peridotites in the plagioclase tectonite domain. The chromitites occur as small lenses, entwined veins or schlierens. These Cr ores contain up to 9 ppb Au and 2 ppm PGE.

 

Some pictures of the most interesting outcrops we visited during the fieldtrip are here below.

 

The field trip was a very good opportunity to understand and correlate the tectonic evolution of the ultramafic massif with the genesis of different types of magmatic ores. We would like to thank Professor Fernando Gervilla for sharing his knowledge and passion for the Ronda Massif.

 

Exceptional outcrop where a layering of serpentinized peridotites (black) and pyroxenites (white) is observed, corresponding to garnet-lherzolites.

 

 

The participants observing an outcrop of foliated peridotites.

 

 

Granular peridotites outcrop. It the upper part it is possible to observed an isoclinally folded pyroxenite vein in the granular non-deformed peridotites.

 

 

Participants of the fieldtrip in the Arroyo de la Cala chromitite outcrop.

 

 

Chromitite outcrop in the Arroyo de los Caballos area.