The Piedemonte Llanero Basin is located on the eastern side of the Eastern Cordillera of the Colombian Andes.It has been the subject of numerous geological studies carried out for the oil sector,mainly.This study pres...The Piedemonte Llanero Basin is located on the eastern side of the Eastern Cordillera of the Colombian Andes.It has been the subject of numerous geological studies carried out for the oil sector,mainly.This study presents the coalpetrographical features of 15 coal seams of four geological formations from Late Cretaceous to Middle Miocene(Chipaque formation,Palmichal group,Arcillas del Limbo formation,and San Fernando formation).Analysis of 33 samples indicates enrichment in vitrinite,while liptinite and inertinite concentrations vary according to the stratigraphic position.Reflectance indicates that the coal range gradually decreases from highly volatile bituminous C(Chipaque formation)to subbituminous C(San Fernando formation).The microlithotypes with the highest concentrations are clarite and vitrinertoliptite.Maceral composition and coal facies indicate changes in the depositional conditions of the sequence.The precursor peat from Late Cretaceous to Late Paleocene accumulated under limnic conditions followed by telmatic in Late Eocene-Early Miocene.The coal facies indices show wet conditions in forest swamps with variations in the flooding surface,influxes of brackish water and good tissue preservation.The tectonic conditions along the Piedemonte Llanero basin is evident,from post-rift to foreland basin,evidenced by oxic and anoxic periods reflected in the maceral composition and its morphology.The coal environment corresponds to an estuarine system started in the Chipaque formation evolving to the lacustrine conditions in the San Fernando formation.展开更多
基金The authors would like to thank the geologists William Monroy,Robinson Patino,and Manuel Sandoval of the Servicio Geologico Colombiano for the detailed work of geological cartography,the description,sampling,and characterization of the coal seams.We are grateful to the professional group of the Chemical Laboratory(part of the Servicio Geologico Colombiano)for the chemical analysis.To the Director of Mineral Resources of the Servicio Geologico Colombiano,Ph.D.Gloria Prieto,for support and believing in this research topic as a fundamental tool in the studies of the Research and Exploration of Energy Mineral Resources.
文摘The Piedemonte Llanero Basin is located on the eastern side of the Eastern Cordillera of the Colombian Andes.It has been the subject of numerous geological studies carried out for the oil sector,mainly.This study presents the coalpetrographical features of 15 coal seams of four geological formations from Late Cretaceous to Middle Miocene(Chipaque formation,Palmichal group,Arcillas del Limbo formation,and San Fernando formation).Analysis of 33 samples indicates enrichment in vitrinite,while liptinite and inertinite concentrations vary according to the stratigraphic position.Reflectance indicates that the coal range gradually decreases from highly volatile bituminous C(Chipaque formation)to subbituminous C(San Fernando formation).The microlithotypes with the highest concentrations are clarite and vitrinertoliptite.Maceral composition and coal facies indicate changes in the depositional conditions of the sequence.The precursor peat from Late Cretaceous to Late Paleocene accumulated under limnic conditions followed by telmatic in Late Eocene-Early Miocene.The coal facies indices show wet conditions in forest swamps with variations in the flooding surface,influxes of brackish water and good tissue preservation.The tectonic conditions along the Piedemonte Llanero basin is evident,from post-rift to foreland basin,evidenced by oxic and anoxic periods reflected in the maceral composition and its morphology.The coal environment corresponds to an estuarine system started in the Chipaque formation evolving to the lacustrine conditions in the San Fernando formation.
