COROCORO COPPER DISTRICT OF BOLIVIA 57 



Vetas and Ramos series there was a period of tilting and 

 faulting with copper mineralization that at least spatially 

 is closely related to the Corocoro fault. The great thickness 

 of the Vetas and Ramos series as determined by the usual 

 methods of measuring thicknesses is probably to be inter- 

 preted as slope deposition or alluviation, since it is certain 

 that the determined thicknesses do not furnish a measure 

 of subsidence, although it is conceivable that they might 

 represent a measure of the differential movement, assuming 

 that there was faulting along the boundary between the 

 high plateau and the western Andes. 



Subsequent to the mineralization from the solutions rising 

 from the underlying dioritic magma, sedimentation was 

 resumed and the Desaguadero series was deposited. 

 Another period of tectonic disturbances resulted in the tilt- 

 ing, minor folding, and faulting of these beds. Since the 

 deposition of the Vetas series the region has undergone a 

 considerable uplift estimated as exceeding 6500 feet. All 

 of this was accomplished subsequent to the close of the 

 Miocene and the later stages may have extended into what 

 was synchronous with the Pleistocene of the Northern 

 Hemisphere although antedating the mountain glaciation of 

 Bolivia. 



THE ORE DEPOSITS 

 EARLIER DESCRIPTIONS 



Corocoro is the most important deposit of a series of 

 similar copper deposits that extend across the Bolivian 

 high plateau from Lake Titicaca to the Chilean border and 

 beyond into the province of Antofagasta as far as San 

 Bartolo. The principal features of this mineralization have 

 long been understood, but no detailed critical study of the 

 ore occurrence such as might lead to a satisfactory interpre- 

 tation of its mode of genesis has ever been made. 



Baron C. A. de la Ribette said the Corocoro formation 

 extends with indications of rich veins from Lake Titicaca 

 to Turco, a distance of 60 leagues. The ores occur in beds 



