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COPYRIGHT 1997 The Mineralogical, Inc.
THE CERRO DE PASCO DISTRICT
Alcides Carrion Province Pasco Department
LOCATION
The Cerro de Pasco district is located about 190 km directly northeast of Lima on the Andean plateau at an elevation of 4,300 meters. The district lies east of the continental divide and west of the Cordillera Oriental.
HISTORY
Cerro de Pasco is one of the most extensively worked districts in Peru; discovered in 1630, it has been active for more than 300 years. Some 558 mines and another 1,000 small excavations were active in 1828. Many of the mine openings were located in peoples' houses for security reasons (Purser, 1971). By the 1840's, the town of Cerro de Pasco had 18,000 people.
In 1901 the Cerro de Pasco Mining Company was formed, and the railway from Lima to the Cerro (as the district was commonly abbreviated) was completed in 1904. The Cerro de Pasco Corporation became formal owners of the district mines in 1902.
Today the major mining at Cerro de Pasco is by open pit methods. The orebody at the Cerro de Pasco mine is estimated to have contained a total of 100 million tons of pyrite, 4 million tons of zinc, 2 million tons of lead (Petersen, 1965), in excess of 1 million tons of copper, 10 thousand tons of silver, and lesser amounts of gold and bismuth.
Cerro de Pasco has been extensively studied, and numerous papers have been written about its geology and ore deposits (McCutchan, 1945; McLaughlin, 1945; Parsons, 1945: Ward, 1961; Petersen, 1965; Purser, 1971; Silberman and Noble, 1977: and Einaudi, 1977). Einaudi (1977) and Ward (1961) did detailed studies of the Cerro, and much of the geologic and orebody data presented here is abstracted from their reports, as well as from the other authors listed above.
GEOLOGY
The Cerro de Pasco orebody is associated with a Tertiary volcanic vent which is located in the core of a broad, north-plunging anticline composed of highly contorted shales, phyllites and quartzites belonging to the Devonian Excelsior Group (McLaughlin, 1924; Jenks, 1951). On the surface, continental red beds of the Permian Mitu Group (Newell et al., 1953) unconformably overlie the Excelsior Group on both limbs of the anticline. The Mitu Group is, however, absent or unrecognized in the underground mine workings. Underground, the Triassic-Jurassic Pucara Limestone appears to overlie the Excelsior Group shales. The Pucara Group, the main lead-zinc ore host rock,...
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