Doctoral Thesis defense by Isaac Corral

Our colleague and member of the Barcelona SGA Student Chapter, Isaac Corral, will defend his thesis, entitled “Geology and Metallogeny of the Cerro Quema Au-Cu Deposit (Azuero Peninsula, Panama)” on Friday 10^th of May. The defense will be held at the Science Faculty (Sala de Graus) of the UAB (Universitat Autònoma de Catalunya) at 11 a.m. Isaac is the first Barcelona SGA Student Chapter member to finish his Doctoral Thesis, so we all wish Isaac all the best with the defense. 

SUMMARY

Cerro Quema, located in the Azuero Peninsula (SW Panama) is a structurally and lithologically controlled high sulfidation epithermal Au-Cu deposit. It is hosted by a dacite dome complex intruded within the Río Quema Formation, a volcanosedimentary sequence of Late Campanian to Maastrichtian age deposited in a fore-arc basin. Au-Cu mineralization and hydrothermal alteration is controlled by E-W trending regional faults.

In order to unravel the relationship between the geological evolution of the area and the Cerro Quema mineralization, a detailed study of the tectonostratigraphy, geochemistry and biostratigraphy of the Azuero Peninsula is presented. Additionally, new data on the ore and alteration (hydrothermal and supergene) mineral parageneses and Ar/Ar geochronology (hornblende) is presented to find out the age of the Au-Cu mineralization. The origin and evolution of mineralizing fluids is discussed from fluid inclusion (homogenization temperature and salinity) and stable isotopes (S, O and H) data performed on sulfides, sulfates and silicates.

According to field observations coupled with geochronological and biostratigraphical data, Cerro Quema is a high sulfidation epithermal deposit emplaced during Lower Eocene (~55-49 Ma) times, and is probably related to an underlying porphyry copper system. Mineralizing fluids were of variable temperature (140 - 240ºC) and low salinity (< 5 wt% NaCl eq.). Hydrothermal fluids were sulfide dominant with sulfur of magmatic origin (δ³⁴S_ΣS= -0.5‰). d¹⁸O of fluids in equilibrium with vuggy silica (-2.6 to +3.0‰) and d¹⁸O/dD values of kaolinite/dickite (d¹⁸O= -10.0 to +13.3‰; dD= -72 to -13‰, respectively), indicate that mineralization was produced by the mixing of hydrothermal fluids with meteoric waters. Cerro Quema is only a part of an extensive hydrothermal system that produced similar deposits in the southern portion of the Azuero Peninsula.