Resumen de Analysis of the evolution and rank distribution of coals from the Oyon basin (Upper Jurassic) of Peru
E.A. Carrascal Miranda, Isabel Suárez Ruiz, L. Martínez
The Oyon Coal Basin (Upper Jurassic) is Jocated in the central part of Peru and it is centered around two nuclei of very fau/ted and strongly tectonized antic/ines. The middleupper part of the Oyon Formation which is representative of the sedimentary registry of this Basin contains the coa/ productive series. This series is formed by sandstones and e/ay sediments among which 5 very fau/ted coa/ seams are interlayered. Coa/s from this Basin are humic and they are mainly composed of vitrinite (85-97% vol.) with a relative to moderate mineral matter content (ash: 6-36%). Their degree of evolution was determined from vitrinite ref/ectance measurements and carbon content. The coa/ rank into this Basin shows a definite distribution which is successively represented by low volatile bituminous coa/s, semi-anthracites, anthracites and metaanthracites. The high degree of evo/ution reached by these coals is due to the high thermal gradient resulting from the Jocation of important intrusive stocks (belonging to the Coast Batho/it) and the subsequent volcanic activity of the different phases of the Andean Orogeny, consequence of the ca/lisian ad subduction processes of the Nazca Plate under South American lithospheric Plate.
