Geology and Tectonics of Northwestern South America, 2019
This paper summarizes geological data from the basement massifs of the northern Andes, which cons... more This paper summarizes geological data from the basement massifs of the northern Andes, which constrains their evolution since Late Proterozoic time. Regional associations, age, and tracer isotopic data suggest that two orogenic episodes—Orinoquiense-Grenvillian (~1.0 Ga) and Quetame-Caparonensis (~0.47 Ga)—consolidated the basement of the northern Andes, here referred to as the Chicamocha terrane. The Paleozoic paleogeography has been refined by establishing connections between provincial fauna. Faunal constraints indicate a Gondwanan affinity in the Cambro-Ordovician and an Appalachian character for the Siluro-Devonian assemblages. In a broader context, the proto Andean Grenvillian-Orinoquiense (~1.0 Ga) and Quetame-Caparonensis-Famatinian (~0.5–0.43 Ga) orogens may be traced from the Andes of Venezuela down to Argentina. A fragment of the Chicamocha terrane and its Cambro-Ordovician cover was “transferred” to southern Mexico in Late Paleozoic time. Permian magmatic belts running a...
Central Macarena seen from the east. Based upon early field studies within the Macarena range and... more Central Macarena seen from the east. Based upon early field studies within the Macarena range and the Roraima tepuis, Augusto Gansser documented the puzzling relationships between the Guiana Shield and the Andean belt, in the process formulating the "Roraima Problem" from a geomorphologic-stratigraphic standpoint. Subsequent studies served to highlight the "problem" within the Macarena uplift, where Cambrian sediments are exposed at approx. 1000 m above sea level whilst Silurian sediments within the Orinoco low are buried at approx. 2300 m depth. The coexistence of vertical tectonics (over 2000 m displacement) and extensional strain systems (Phanerozoic graben-rift fills), with thrust-and-fold belts, may point to concealed wrench structures in subsurface, undetected by geophysical methods. An updated synthesis of the Roraima Problem, using new surface and sub-surface cartographic and structural data, is presented within
Background measurements of gamma radiation were made on the Jordán (Upper Permian ?), Guatapurí (... more Background measurements of gamma radiation were made on the Jordán (Upper Permian ?), Guatapurí (Triassic ?), Girón (Triassic-Jurassic), Ranchogrande (Triassic-Jurassic ?) and Morrocoyal (Lower Jurassic) Formations in northeastern Colombia. The lutites of the Girón Formation produce the highest values (impulses y per minute). In the region of Bucaramanga (Dept. of Santander), the redbeds of the Jordán and Girón Formations give quite different radiometric values. The usefulness of radiomatric measurements as a means of differentiating stratigraphic units and facies changes is discussed.
En su localidad tipo (río Lebrija, cordillera Oriental de Colombia), el Grupo Girón está compuest... more En su localidad tipo (río Lebrija, cordillera Oriental de Colombia), el Grupo Girón está compuesto por una serie de areniscas e intercalaciones periódicas de lutitas rojas (red beds), de una potencia total aproximada de 4840 m. La columna estratigráfica tipo se puede dividir litológicamente en dos formaciones: 1) La Formación Girón (± 4650 m.), de edad triásica-jurásica, y 2) La Formación Los Santos (± 190 m.), que cubre concordantemente la primera y probablemente pertenece al Berriasiano. La Formación Girón está constituida por subgrauwacas y lutitas rojas depositadas en un ambiente fluviátil o limno-fluviátil principalmente. La Formación Los Santos, un depósito marino de protocuarcitas, contiene intercalaciones ocasionales de red beds y, o shales oscuros. El Grupo Girón cubre discordantemente sedimentos marinos del Devoniano, Carboniano y Permiano (Formaciones Bocas y Jordán); localmente reposa directamente sobre rocas cristalinas. Este grupo representa una molasa típica post-varí...
The geological, geophysical and geochemical data pertaining the previously known as Choco Basin, ... more The geological, geophysical and geochemical data pertaining the previously known as Choco Basin, was compiled and reinterpreted. Today, two distinc Cenozoic basins, the Atrato Basin and the San Juan Basin are identified, each with its own geological history. They are bounded by the IstminaCondoto Structural High, in fact, a paleo-high which intermitently acts as sedimentary barrier, i.e. source area. In the San Juan Delta Basin up to 9 km (?) of mainly clastic sediments were deposited, most probably since Paleocene time. In the Atrato Fore Arc Basin a 10 km thickness of Cenozoic sediments were seismically recorded. Both basins are sufficiently structured, as to produce potential hydrocarbon traps, mainly post-Miocene in age. The tecto-sedimentary framework in the San Juan Basin is controlled by the Istmina-Condoto Fault System in the NW and the Garrapatas Fault System in the SE. In the Atrato Basin the occurrence of growth faults is an outstanding feature.
Based primarily on geologic field observations as recorded by numerous geoscientists over the las... more Based primarily on geologic field observations as recorded by numerous geoscientists over the last three decades, backed by more recent geochemical, seismic, gravity, magnetic, tomographic, and satellite-based techniques, an integrated synthesis and interpretation of the tectonic assembly of the entire Northern Andean Block (the Andes of Ecuador, Colombia, and Venezuela) is presented. Tectonic reconstruction is based on the identification and characterization of more than 30 distinct lithotectonic and morphostructural units (including terranes, terrane assemblages, physiographic domains, etc.) and their bounding suture and fault systems, which, based on geologic, geophysical, and dynamo-tectonic considerations, define four distinct tectonic realms representing the entire Northern Andean region. These include the Guiana Shield Realm (GSR), the Maracaibo subplate Realm (MSP), the Central Continental subplate Realm (CCSP), and the Western Tectonic Realm (WTR). The GSR provided the back...
Mediante una exhaustiva recopilacion de la informacion geologica, geofisica y geoquimica disponib... more Mediante una exhaustiva recopilacion de la informacion geologica, geofisica y geoquimica disponible de la Cuenca Tumaco (costa adentro y costa afuera), por encargo de la ANH, se realizo una integracion y evaluacion de la misma en aras de identificar los elementos que tienen mayor relevancia en la generacion y expulsion de hidrocarburos, asi como su entendimiento dentro de un marco geologico regional. La Cuenca Antearco Tumaco esta compuesta por una megasecuencia premiocenica y tres secuencias posteriores al Mioceno Inferior, las cuales fueron depositadas en ambientes marinos de plataforma y talud. A pesar de que la informacion estratigrafica obtenida de los cinco pozos exploratorios perforados en esta cuenca no ha permitido la definicion formal de unidades litoestratigraficas, se logro identificar espesores de depositos clasticos separados por inconformidades y diferenciados por edades y que pueden alcanzar hasta 9 (?) kilometros de espesor. Las unidades diferenciadas son: Mioceno T...
... south america basement tectonics and implications for paleocontinen tal reconstructions of th... more ... south america basement tectonics and implications for paleocontinen tal reconstructions of the americas Pedro A. Restrepo-Pace, Fabio Cediel PII ... granitoids along the Central Cordillera of Colombia have been interpreted to indicate here the closure of Pangea (Vinasco, 2004) . ...
Este artículo es una síntesis de la compilación, evaluación y re-interpretación de la información... more Este artículo es una síntesis de la compilación, evaluación y re-interpretación de la información geológica, geofísica y geoquímica de las Cuencas Atrato y San Juan. En el área anteriormente denominada como Cuenca Chocó, hoy se distinguen dos cuencas Cenozoicas con ...
Geology and Tectonics of Northwestern South America, 2019
This paper summarizes geological data from the basement massifs of the northern Andes, which cons... more This paper summarizes geological data from the basement massifs of the northern Andes, which constrains their evolution since Late Proterozoic time. Regional associations, age, and tracer isotopic data suggest that two orogenic episodes—Orinoquiense-Grenvillian (~1.0 Ga) and Quetame-Caparonensis (~0.47 Ga)—consolidated the basement of the northern Andes, here referred to as the Chicamocha terrane. The Paleozoic paleogeography has been refined by establishing connections between provincial fauna. Faunal constraints indicate a Gondwanan affinity in the Cambro-Ordovician and an Appalachian character for the Siluro-Devonian assemblages. In a broader context, the proto Andean Grenvillian-Orinoquiense (~1.0 Ga) and Quetame-Caparonensis-Famatinian (~0.5–0.43 Ga) orogens may be traced from the Andes of Venezuela down to Argentina. A fragment of the Chicamocha terrane and its Cambro-Ordovician cover was “transferred” to southern Mexico in Late Paleozoic time. Permian magmatic belts running a...
Central Macarena seen from the east. Based upon early field studies within the Macarena range and... more Central Macarena seen from the east. Based upon early field studies within the Macarena range and the Roraima tepuis, Augusto Gansser documented the puzzling relationships between the Guiana Shield and the Andean belt, in the process formulating the "Roraima Problem" from a geomorphologic-stratigraphic standpoint. Subsequent studies served to highlight the "problem" within the Macarena uplift, where Cambrian sediments are exposed at approx. 1000 m above sea level whilst Silurian sediments within the Orinoco low are buried at approx. 2300 m depth. The coexistence of vertical tectonics (over 2000 m displacement) and extensional strain systems (Phanerozoic graben-rift fills), with thrust-and-fold belts, may point to concealed wrench structures in subsurface, undetected by geophysical methods. An updated synthesis of the Roraima Problem, using new surface and sub-surface cartographic and structural data, is presented within
Background measurements of gamma radiation were made on the Jordán (Upper Permian ?), Guatapurí (... more Background measurements of gamma radiation were made on the Jordán (Upper Permian ?), Guatapurí (Triassic ?), Girón (Triassic-Jurassic), Ranchogrande (Triassic-Jurassic ?) and Morrocoyal (Lower Jurassic) Formations in northeastern Colombia. The lutites of the Girón Formation produce the highest values (impulses y per minute). In the region of Bucaramanga (Dept. of Santander), the redbeds of the Jordán and Girón Formations give quite different radiometric values. The usefulness of radiomatric measurements as a means of differentiating stratigraphic units and facies changes is discussed.
En su localidad tipo (río Lebrija, cordillera Oriental de Colombia), el Grupo Girón está compuest... more En su localidad tipo (río Lebrija, cordillera Oriental de Colombia), el Grupo Girón está compuesto por una serie de areniscas e intercalaciones periódicas de lutitas rojas (red beds), de una potencia total aproximada de 4840 m. La columna estratigráfica tipo se puede dividir litológicamente en dos formaciones: 1) La Formación Girón (± 4650 m.), de edad triásica-jurásica, y 2) La Formación Los Santos (± 190 m.), que cubre concordantemente la primera y probablemente pertenece al Berriasiano. La Formación Girón está constituida por subgrauwacas y lutitas rojas depositadas en un ambiente fluviátil o limno-fluviátil principalmente. La Formación Los Santos, un depósito marino de protocuarcitas, contiene intercalaciones ocasionales de red beds y, o shales oscuros. El Grupo Girón cubre discordantemente sedimentos marinos del Devoniano, Carboniano y Permiano (Formaciones Bocas y Jordán); localmente reposa directamente sobre rocas cristalinas. Este grupo representa una molasa típica post-varí...
The geological, geophysical and geochemical data pertaining the previously known as Choco Basin, ... more The geological, geophysical and geochemical data pertaining the previously known as Choco Basin, was compiled and reinterpreted. Today, two distinc Cenozoic basins, the Atrato Basin and the San Juan Basin are identified, each with its own geological history. They are bounded by the IstminaCondoto Structural High, in fact, a paleo-high which intermitently acts as sedimentary barrier, i.e. source area. In the San Juan Delta Basin up to 9 km (?) of mainly clastic sediments were deposited, most probably since Paleocene time. In the Atrato Fore Arc Basin a 10 km thickness of Cenozoic sediments were seismically recorded. Both basins are sufficiently structured, as to produce potential hydrocarbon traps, mainly post-Miocene in age. The tecto-sedimentary framework in the San Juan Basin is controlled by the Istmina-Condoto Fault System in the NW and the Garrapatas Fault System in the SE. In the Atrato Basin the occurrence of growth faults is an outstanding feature.
Based primarily on geologic field observations as recorded by numerous geoscientists over the las... more Based primarily on geologic field observations as recorded by numerous geoscientists over the last three decades, backed by more recent geochemical, seismic, gravity, magnetic, tomographic, and satellite-based techniques, an integrated synthesis and interpretation of the tectonic assembly of the entire Northern Andean Block (the Andes of Ecuador, Colombia, and Venezuela) is presented. Tectonic reconstruction is based on the identification and characterization of more than 30 distinct lithotectonic and morphostructural units (including terranes, terrane assemblages, physiographic domains, etc.) and their bounding suture and fault systems, which, based on geologic, geophysical, and dynamo-tectonic considerations, define four distinct tectonic realms representing the entire Northern Andean region. These include the Guiana Shield Realm (GSR), the Maracaibo subplate Realm (MSP), the Central Continental subplate Realm (CCSP), and the Western Tectonic Realm (WTR). The GSR provided the back...
Mediante una exhaustiva recopilacion de la informacion geologica, geofisica y geoquimica disponib... more Mediante una exhaustiva recopilacion de la informacion geologica, geofisica y geoquimica disponible de la Cuenca Tumaco (costa adentro y costa afuera), por encargo de la ANH, se realizo una integracion y evaluacion de la misma en aras de identificar los elementos que tienen mayor relevancia en la generacion y expulsion de hidrocarburos, asi como su entendimiento dentro de un marco geologico regional. La Cuenca Antearco Tumaco esta compuesta por una megasecuencia premiocenica y tres secuencias posteriores al Mioceno Inferior, las cuales fueron depositadas en ambientes marinos de plataforma y talud. A pesar de que la informacion estratigrafica obtenida de los cinco pozos exploratorios perforados en esta cuenca no ha permitido la definicion formal de unidades litoestratigraficas, se logro identificar espesores de depositos clasticos separados por inconformidades y diferenciados por edades y que pueden alcanzar hasta 9 (?) kilometros de espesor. Las unidades diferenciadas son: Mioceno T...
... south america basement tectonics and implications for paleocontinen tal reconstructions of th... more ... south america basement tectonics and implications for paleocontinen tal reconstructions of the americas Pedro A. Restrepo-Pace, Fabio Cediel PII ... granitoids along the Central Cordillera of Colombia have been interpreted to indicate here the closure of Pangea (Vinasco, 2004) . ...
Este artículo es una síntesis de la compilación, evaluación y re-interpretación de la información... more Este artículo es una síntesis de la compilación, evaluación y re-interpretación de la información geológica, geofísica y geoquímica de las Cuencas Atrato y San Juan. En el área anteriormente denominada como Cuenca Chocó, hoy se distinguen dos cuencas Cenozoicas con ...
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