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Articles 1 - 5 of 5
Full-Text Articles in Earth Sciences
Evolution Of The Stress And Strain Fields In The Eastern Cordillera, Colombia, Obi Egbue, James N. Kellogg
Evolution Of The Stress And Strain Fields In The Eastern Cordillera, Colombia, Obi Egbue, James N. Kellogg
James N Kellogg
This work integrates stress data from Global Positioning System measurements and earthquake focal mechanism solutions, with new borehole breakout and natural fracture system data to better understand the complex interactions between the major tectonic plates in northwestern South America and to examine how the stress regime in the Eastern Cordillera and the Llanos foothills in Colombia has evolved through time. The dataset was used to generate an integrated stress map of the northern Andes and to propose a model for stress evolution in the Eastern Cordillera. In the Cordillera, the primary present-day maximum principal stress direction is WNW-ESE to NW-SE, …
Three-Dimensional Structural Evolution And Kinematics Of The Piedemonte Llanero, Central Llanos Foothills, Eastern Cordillera, Colombia, Obi Egbue, James N. Kellogg
Three-Dimensional Structural Evolution And Kinematics Of The Piedemonte Llanero, Central Llanos Foothills, Eastern Cordillera, Colombia, Obi Egbue, James N. Kellogg
James N Kellogg
The Piedemonte Llanero is a wedge duplex zone in the Llanos foothills on the eastern flank of the Eastern Cordillera of Colombia. It is located northeast of the Cusiana and Cupiagua hydrocarbon fields. The area is characterized by a series of moderate to high-angle duplexes with east-southeast verging thin-skinned and thick-skinned tectonics.We present a structural model constrained by 2-D and 3-D seismic reflection data, surface geology, and well data. The structural analysis is based on backward modeling (kinematic restoration) and forward modeling using transfer-flexural slip and fault slip fold algorithms. The structures are significantly tighter in the northern segment compared …
Pleistocene To Present North Andean “Escape”, James N. Kellogg, Obi Egbue
Pleistocene To Present North Andean “Escape”, James N. Kellogg, Obi Egbue
James N Kellogg
This study compiles 20 published field geologic estimates of displacement rates for the northern Andes, such as displaced glacial moraines and offset pyroclastic flow, and compares them to published Global Positioning System (GPS) measurements. Dated displacements compiled in this study were obtained from the Gulf of Guayaquil, Pallatanga, Chingual-la Sofia, and Cayambe-Afiladores-Sibundoy fault systems in Ecuador and southern Colombia and the Boconó fault system in Venezuela. Right-lateral slip estimates on the individual fault segments range from 2 mm/a to 10 mm/a. The mean estimated geologic slip rate for the last 86,000 years is 7.6 mm/a. This estimate is very similar …
Wide Plate Margin Deformation, Southern Central America And Northwestern South America, Casa Gps Observations, James Kellogg
Wide Plate Margin Deformation, Southern Central America And Northwestern South America, Casa Gps Observations, James Kellogg
James N Kellogg
Global Positioning System (GPS) data from southern Central America and northwestern South America were collected during 1991, 1994, 1996, and 1998 in Costa Rica, Panama, Ecuador, Colombia and Venezuela. These data reveal wide plate boundary deformation and escape tectonics occurring along an approximately 1400 km length of the North Andes; locking of the subducting Nazca plate and strain accumulation in the Ecuador-Colombia forearc; ongoing collision of the Panama arc and Colombia; and convergence of the Caribbean plate with Panama and South America. Elastic modeling of observed horizontal displacements in the Ecuador forearc is consistent with partial locking (50%) in the …
Subduction Of The Caribbean Plate And Basement Uplifts In The Overriding South American Plate, James N. Kellogg, William E. Bonini
Subduction Of The Caribbean Plate And Basement Uplifts In The Overriding South American Plate, James N. Kellogg, William E. Bonini
James N Kellogg
Abstract. The new tectonic interpretations presented in this paper are based on geologic field mapping and gravity data supplemented by well logs, seismic profiles, and radiometric and earthquake data. The present Caribbean-South American plate boundary is the South Caribbean marginal fault, where subduction is indicated by folding and thrusting in the deformed belt and a seismic zone that dips 30o to the southeast and terminates 200 km below the Maracaibo Basin. The Caribbean-South American convergence rate is estimated as 1.9 +_. 0.3 cm/yr on the basis of the 390-km length of the seismic zone and a thermal equilibration time of …