Barinas Basin Research Articles

The detrital record of late‐Miocene to Pliocene surface uplift and exhumation of the Venezuelan Andes in the Maracaibo and Barinas foreland basins

AbstractA multidisciplinary approach, combining sediment petrographic, palynological and thermochronological techniques, has been used to study the Miocene‐Pliocene sedimentary record of the evolution of the Venezuelan Andes. Samples from the Maracaibo (pro‐wedge) and Barinas (retro‐wedge) foreland basins, proximal to this doubly vergent mountain belt, indicate that fluvial and alluvial‐fan sediments of similar composition were shed to both sides of the Venezuelan Andes. Granitic and gneissic detritus was derived from the core of the mountain belt, whereas sedimentary cover rocks and uplifted foreland basin sediments were recycled from its flanks. Palynological evidence from the Maracaibo and Barinas basins constrains depositional ages of the studied sections from late Miocene to Pliocene. The pollen assemblages from the Maracaibo Basin are indicative of mountain vegetation, implying surface elevations of up to 3500–4000 m in the Venezuelan Andes at this time. Detrital apatite fission‐track (AFT) data were obtained from both stratigraphic sections. In samples from the Maracaibo basin, the youngest AFT grain‐age population has relatively static minimum ages of 5 ± 2 Ma, whereas for the Barinas basin samples AFT minimum ages are 7 ± 2 Ma. With exception of two samples collected from the Eocene Pagüey Formation and from the very base of the Miocene Parángula Formation, no evidence for resetting and track annealing in apatite due to burial heating in the basins was found. This is supported by rock‐eval analyses on organic matter and thermal modelling results. Therefore, for all other samples the detrital AFT ages reflect source area cooling and impose minimum age constraints on sediment deposition. The main phase of surface uplift, topography and relief generation, and erosional exhumation in the Venezuelan Andes occurred during the late Miocene to Pliocene. The Neogene evolution of the Venezuelan Andes bears certain similarities with the evolution of the Eastern Cordillera in Colombia, although they are not driven by exactly the same underlying geodynamic processes. The progressive development of the two mountain belts is seen in the context of collision of the Panama arc with northwestern South America and the closure of the Panama seaway in Miocene times, as well as contemporaneous movement of the Caribbean plate to the east and clock‐wise rotation of the Maracaibo block.

Linked basin sedimentation and orogenic uplift: The Neogene Barinas basin sediments derived from the Venezuelan Andes

Abstract The Venezuelan Andes are an asymmetric, doubly vergent orogen that is flanked on its southeastern side by the Barinas basin. Analyses of sedimentary facies, sandstone petrography, apatite fission-tracks, and magnetostratigraphy were completed on a 1750-m section of the syn-orogenic Neogene Parangula and Rio Yuca formations in the Barinas side foothills of the Venezuelan Andes. Our sedimentary facies analyses record a progression of sedimentary environments from floodplain and floodplain channel deposits through the 560-m thick Parangula Formation transitioning to distal alluvial fan deposits in the lower Rio Yuca Formation and finally to an alternation of distal alluvial fan and two, ∼100-m thick organic-rich lacustrine deposits in the upper third of the section. Major- and minor-mineral petrographic analysis reveals unroofing of the Venezuelan Andes, with quartz arenite composition low in the section succeeded by metamorphic and igneous clasts and potassium feldspar appearing near the base of the Rio Yuca Formation. Apatite fission-track (AFT) analysis of sandstones and pebbles generated ages of 11.2 ± 1.3 – 13.8 ± 2.0 Ma over ∼1100 m of stratigraphic section. Thermal modeling of the detrital AFT and vitrinite data from the lower Rio Yuca Formation indicates exhumation of the source area was occurring by 12–13 Ma, surface exposure at 10–9 Ma, maximum burial by 4–2 Ma and exhumation of the sedimentary package starting 3–2 Ma. Accumulation of the Rio Yuca Formation is contemporaneous with a basinward migration of the deformation front. Regional considerations indicate that the Venezuelan Andes evolved from a primarily singly vergent orogen to its current double vergence over the interval of Neogene-Quaternary sedimentation.

Azimuthal offset‐dependent attributes applied to fracture detection in a carbonate reservoir

Offset‐dependent attributes—amplitude versus offset (AVO) and frequency versus offset—are extracted from 2‐D P‐wave seismic data using the multiple signal classification technique. These attributes are used to detect fracture orientation in a carbonate reservoir located in the Maporal field in the Barinas basin of southwestern Venezuela. In the fracture normal direction, P‐wave reflectivity is characterized by a large increase of amplitude with offset (large positive AVO gradient) and a large decrease of frequency with offset (large negative frequency versus offset gradient). In the fracture strike direction, P‐wave reflectivity shows a scattered variation in AVO but a small variation in frequency with offset. Our results also show that the reservoir heterogeneity can lead to large variations of AVO signatures and that using azimuthal offset‐dependent frequency attributes can help lessen the ambiguity when detecting fracture orientation.

Detection of fracture orientation using azimuthal variation ofP-wave AVO responses

Azimuthally dependent P-wave amplitude variation with offset (AVO) responses can be related theoretically to open fracture orientation and have been suggested as a geophysical tool to identify fracture orientation in fractured oil and gas reservoirs. A field experiment conducted recently over a fractured reservoir in the Barinas Basin, Venezuela provides data for an excellent test of this approach. Three lines of data were collected in three different azimuths, and three component receivers were used. The distribution of fractures in this reservoir was obtained previously using measurements of shear‐wave splitting from P-S converted waves from the same data set. In this work, we use P-wave data to see if the data can yield the same information using azimuthal variation of P-wave AVO responses. Results obtained from the azimuthal P-wave AVO analysis corroborate the fracture orientation obtained previously using P-S converted waves. This analysis with field data is an example of the high potential of P-waves to detect fracture effects on seismic wave propagation.

Abstract: Stratigraphy and Sedimentary Facies of the Eocene Gobernador Formation, Barinas Basin, Western Venezuela.

Abstract: Stratigraphy and Sedimentary Facies of the Eocene Gobernador Formation, Barinas Basin, Western Venezuela.

Tectonic inheritance, crustal architecture, and contrasting structural styles in the Venezuela Andes

Surface and subsurface data image contrasting structural styles for the two flanks of the Venezuela Andes. In the north, a flexural basin developed in Neogene times between the Andes and the Lake Maracaibo. North verging thrusts are mainly detached in the pre‐Cretaceous substratum and form a deeply buried antiformal stack. Secondary décollement levels occur both in the Upper Cretaceous and Tertiary strata, accounting for the passive roof thrust of a conventional frontal triangle zone. In the south, the Barinas basin hardly compares with a flexural basin. It is largely dominated by both north and south verging basement‐involving structures. Paleogene normal faults are locally inverted, and Caribbean nappes are frequently reactivated or refolded by younger oblique Neogene Andean structures. Seismic profiles in this area also attest to the strong Neogene structural inversion of Upper Jurassic‐Lower Cretaceous grabens. Hercynian, or more likely Early Paleozoic structures account for local preexisting crustal heterogeneities, reactivated during both the Tethyan rifting and the Andean deformations. Two trans‐Andean regional profiles have been balanced and constrained by an inversion of the gravimetric data. They imply a progressive deepening of the northern Moho and a south dipping subduction of the infracontinental lithospheric mantle of the Maracaibo block. The shortening for both sections averages 60 km. Palinspastic restorations assume a relative cylindricity for the deep crustal architecture of the Andes and minimize the possible effects of a progressive right‐lateral escape of the Maracaibo block with respect to stable South America along the Bocono Fault. Strain partitioning during Neogene oblique convergence induced surficial thrust fronts parallel to the plate boundary, strike‐slip motion in the allochthon along the Bocono Fault, and an asymmetric subduction (wedging) at depth.

Paleogeographic Control of Sedimentation Patterns of the Middle Eocene Formations in the Barinas Basin and Subandean Foothills, Western Venezuela : ABSTRACTS

Paleogeographic Control of Sedimentation Patterns of the Middle Eocene Formations in the Barinas Basin and Subandean Foothills, Western Venezuela : ABSTRACTS

The Dolomitized O"Limestone in the Barinas Basin: A Hydrocarbon Reservoir in Carbonates Rocks: ABSTRACT"

The Dolomitized O"Limestone in the Barinas Basin: A Hydrocarbon Reservoir in Carbonates Rocks: ABSTRACT"

Tectonic Inheritance, Crustal Architecture and Contrasting Structural Styles along the Northern and Southern Andean Flanks, Venezuela: ABSTRACT

Regional seismic profiles, exploration wells, geological maps and field studies image contrasting structural styles of the northern and southern flank of the Venezuelan Andes. In the north, a flexural basin developed in Neogene times between the Andes and the Maracaibo Lake. North verging thrusts are mainly detached in the pre-Cretaceous substratum and form a deeply buried antiformal stack, whereas secondary decollement levels occur either in the Lower Cretaceous or in the Tertiary, accounting for the passive roof thrusting of the frontal triangle zone. In the south, the Barinas Basin can hardly be compared with a flexural basin. It is largely dominated by basement involved structures, either north or south verging. Tectonic inheritance is obvious, as Paleogene normal faults have been locally inverted, and early Caribbean nappes (Paleogene structures) are frequently reactivated or refolded by younger oblique Andean (Neogene) structures. All these data have been integrated to compile two crustal scale balanced sections which have been constrained by an inversion of the gravimetric data. The Present relief of sections is directly inherited from the Jurassic (Tethyan) rifting event. The southern low land results from the structural inversion of Jurassic extensional structures (thin initial crust), whereas the northern culmination relates to newlymore » created Andean structures (thick Jurassic crust). Whether the Hercynian structures have been or not reactivated during the Tethyan rifting or the Andean deformation, remains an open question. The Hercynian thrusts trend more or less parallels to the younger structures, especially Mesozoic extensional ones which could thus partially result from the negative inversion (collapse) of the Paleozoic edifice.« less

Sedimentation in the Barinas Basin and Uplift of Merida Andes Venezuela, Constrained by New Temporal Data: ABSTRACT

Sedimentation in the Barinas Basin and Uplift of Merida Andes Venezuela, Constrained by New Temporal Data: ABSTRACT

Chronostratigraphy and Biofacies of the Middle Eocene Paguey Formation: An Invaluable Tool for Hydrocarbon Exploration in the Barinas Basin, Western Venezuela: ABSTRACT

Paleoenvironmental changes within the Paguey Formation gave rise to foraminiferal assemblages which can be used for reservoir depth prognosis and subsurface correlation. The chronostratigraphic framework is provided by the integration of palynological, foraminiferal and calcareous nannoplankton data. The interval spans approximately from 43.0 Ma to 39.4 Ma. A transgressive-regressive second order cycle can be interpreted, since a very rapid deepening takes place at the base, where paleoenvironments vary from middle neritic in the south, to bathyal in the north. Within the lower half of the unit, a gradual filling of the basin begins, with paleoenvironments becoming progressively shallower toward the top of the unit. This formation is a 660-m-thick stratigraphic unit, composed mainly of dark gray mudstones, with fine grained glauconitic sandstones toward the base. It conformably overlies the middle Eocene Gobemador Formation and unconformably underlies the Parangula Formation. The characteristic biofacies are constituted by: Planktic zone (T robri/Globigerina sp.), Nummulites sp., Eggerella/Textularia, Quinqueloculina seminula, Ammobaculites/pteropods. The Nummulites sp. biofacies constitutes the most useful marker, since it extends across the whole basin. From the top of this zone to the top of the reservoir, a thickness of about 50 m in the south to 170 m in the north ismore » observed. The precise prognosis of the reservoir depth is essential during the course of the drilling phase, in order to get the maximum geological information from cores at the lowest economic cost.« less

Chronostratigraphy and Regional Distribution of the Cretaceous-Tertiary and Upper Cretaceous (Maastrichtian-Campanian) Unconformities, Barinas Basin, Southwestern Venezuela: ABSTRACT

Chronostratigraphy and Regional Distribution of the Cretaceous-Tertiary and Upper Cretaceous (Maastrichtian-Campanian) Unconformities, Barinas Basin, Southwestern Venezuela: ABSTRACT

A New Paleogeographic Interpretation of Barinas Basin, Western Venezuela, During Eocene: ABSTRACT

A New Paleogeographic Interpretation of Barinas Basin, Western Venezuela, During Eocene: ABSTRACT

Structural Style on Southern Flank of Merida Andes, Venezuela

The Merida Andes exhibit the most complex tectonics in western Venezuela. By studying the different ages and regional distribution of rocks, we can describe some tectonic features which are of interest to oil exploration in this area. Vertical basement movements accompanied extensional tectonics from pre-Cambrian until Eocene times. For this time interval, we reconstructed diverse normal fault systems and associated subsidence. From Eocene time onwards, compressional tectonics gave origin to anticlines and reverse, thrust and back-thrust faults. Neo-tectonic movements have modified existing structures by dislocation along transcurrent fault systems. Geochemical analyses have determined the presence of hydrocarbon source rocks equivalent to the a Luna Formation of the Maracaibo Basin; seismic, surface and subsurface data prove the existence of excellent seals in the Eocene Paguey Shale. The principal problem is to determine the timing of hydrocarbon migration with respect to the timing of trap formation. It is highly probable that the sapropelic strata of the Navay Formation, equivalent to the La Luna Formation, is presently expelling hydrocarbons to traps in the Barinas Basin, under presently existing temperature-pressure conditions.

Guarumen/Carora: Hydrocarbon prospect evaluation using a new geologic model

Guarumen is a virgin exploration area (Figure 1) located between the petroliferous basins of Barinas to the southwest and Guarico to the east, and south of the Venezuelan Andes mountain front. It is also on trend with the basement high (El Baul Arch) that separates the Barinas basin from the Guarico basin. Past exploration activity is limited to corehole studies, aeromagnetics and J.F. Stephan’s 1977 and 1985 studies of surface geology over the Andean uplift between Guarumen and Carora.

Geologic Structure of a Part of the Barinas Mountain Front, Venezuelan Andes

Research Article| March 01, 1969 Geologic Structure of a Part of the Barinas Mountain Front, Venezuelan Andes CARLOS SCHUBERT CARLOS SCHUBERT Dirección de Geología, Ministerio de Minas e Hidrocarburos, Caracas, Venezuela Search for other works by this author on: GSW Google Scholar Author and Article Information CARLOS SCHUBERT Dirección de Geología, Ministerio de Minas e Hidrocarburos, Caracas, Venezuela Publisher: Geological Society of America Received: 19 Jan 1968 Revision Received: 19 Aug 1968 First Online: 02 Mar 2017 Online ISSN: 1943-2674 Print ISSN: 0016-7606 Copyright © 1969, The Geological Society of America, Inc. Copyright is not claimed on any material prepared by U.S. government employees within the scope of their employment. GSA Bulletin (1969) 80 (3): 443–548. https://doi.org/10.1130/0016-7606(1969)80[443:GSOAPO]2.0.CO;2 Article history Received: 19 Jan 1968 Revision Received: 19 Aug 1968 First Online: 02 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation CARLOS SCHUBERT; Geologic Structure of a Part of the Barinas Mountain Front, Venezuelan Andes. GSA Bulletin 1969;; 80 (3): 443–548. doi: https://doi.org/10.1130/0016-7606(1969)80[443:GSOAPO]2.0.CO;2 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGSA Bulletin Search Advanced Search Abstract The following lithologic units are exposed in the Barinitas-Santo Domingo region, southeastern Venezuelan Andes: (1) the Precambrian (?) Iglesias Group, forming the metamorphosed basement; (2) the Lower Paleozoic (?) Cerro Azul Formation, a phyllite sequence; (3) the Upper Paleozoic Palmarito Formation, mostly fossiliferous limestones and shales; (4) the Triassic-Jurassic La Quinta Formation, a continental sequence of red beds; (5) the rocks of the Cretaceous transgression and regression, consisting of the Río Negro, Apón, Aguardiente, Maraca, La Luna, and Colón-Mito Juan Formations; and (6) the Upper Eocene Gobernador and Pagüey Formations, disconformably overlying the Cretaceous sequence.Three granitic intrusions crop out, two of which, the La Soledad Quartz Monzonite and the hornblende granodiorite of Cerro Azul, intrude the Cerro Azul Formation. They were dated by the potassium-argon method as Middle Pennsylvanian and Early Devonian, respectively.The principal structural units present in the map area are enormous blocks of basement rocks (Iglesias Group) which are separated by steeply northwestward-dipping, or nearly vertical reverse faults (upthrusts), along which the blocks have been uplifted or depressed. Along the east flank of the mountain range toward the Barinas Basin the sedimentary cover has been folded into a monocline which is itself broken into blocks by steep faults. In the higher parts of the region, toward the central part of the mountain range, is a zone of extension which produced grabens. horsts, and stepped faults, represented by the Boconó fault zone.The present uplift of the Venezuelan Andes took place in post-Eocene time. Upper Eocene sediments of the Pagüey Formation, poorly consolidated during the initial stages of the uplift, were deformed by slumping, into cascade folds (overturned to the southeast), and also slid down-slope as chaotically oriented blocks which cover the Upper Eocene sediments in situ. Vertical uplift, probably combined with arching or tilting of the region, produced the steep thrust faults along the margin of the range, and also the zone of extension represented by the Boconó fault zone. Strike-slip movement of great magnitude probably has not taken place along this fault. This content is PDF only. Please click on the PDF icon to access. First Page Preview Close Modal You do not have access to this content, please speak to your institutional administrator if you feel you should have access.