Oscar R. López-Gamundí

Euroconsultants (Greece)

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Eduardo A. Rossello

Fundación Ciencias Exactas y Naturales

Marcos E. Mozetic

Elabora Consultoria (Brazil)

Andrea F. Sterren

Universidad Nacional de Córdoba

Gabriela A. Cisterna

Consejo Nacional de Investigaciones Científicas y Técnicas

P.R. Cobbold

Université de Rennes

Héctor de Santa Ana

Agencia Nacional de Investigación e Innovación

Carlos O. Limarino

University of Buenos Aires

Luís A. Buatois

University of Saskatchewan

Ingrid Cordon

Stanford University

Gerardo Veroslavsky

Universidad de la República

Cooperative Institutions

Consejo Nacional de Investigaciones Científicas y Técnicas

University of Buenos Aires

Centro Científico Tecnológico - Tucumán

Centre National de la Recherche Scientifique

Géosciences Rennes

Université de Rennes

University of Potsdam

Centro de Información y Desarrollo de la Mujer

Fundación Ciencias Exactas y Naturales

Universidad Nacional de Córdoba

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Influencias de la Tectónica Andina sobre la Plataforma Continental Atlántica (Uruguay-Argentina)?: Controles sobre su Potencial Exploratorio [PAPER IN SPANISH] Influences of Andean Tectonics on the Atlantic Continental Shelf (Uruguay-Argentina): Controls

Eduardo A. Rossello Héctor de Santa Ana Oscar R. López-Gamundí Gerardo Veroslavsky UdelaR

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Influencias de la tectónica Andina sobre la Plataforma Continental Atlántica (Uruguay-Argentina)?: Controles sobre su potencial exploratorio

Oscar R. López-Gamundí

The shallow (0-200 m) part of the continental shelf of Uruguay and Argentina along the Buenos Aires province has been affected by significant extension that created a series of depocenters known, from north to south, as the Pelotas, Punta del Este, Salado and Colorado basins. The initial fill phase of these depocenters is characterized by Jurassic to Cretaceous sedimentary deposits associated to a rift phase that initiated the opening of the South Atlantic. This initial fill is followed by a passive margin phase characterized by prograding clinoforms during the Tertiary. These basins have a heterogeneous basement made up of a) Paleozoic sedimentary rocks, equivalent to those exposed in the Parana (Brazil, Uruguay) and Karoo (South Africa) basins and the Sierras Australes of Buenos Aires (Argentina) and, b) crystalline rocks as inferred by highs in the gravity maps. Recent 2D seismic data acquired by ANCAP allowed us to recognize new structures related to Andean transpressional reactivation of earlier rift structures. This reactivation was facilitated by, and located along, previous extensional faults that acted as possible mechanical anisotropies. In consequence, some border fault margins of rifts show subsequent inversion probably linked to the Andean compression generated along the Pacific margin of the South American continent due to the subduction of the Nazca plate. This compression later propagated across the continent to the Atlantic margin. On the other hand, the Jurassic-Cretaceous rifts show dominant westward vergence, opposite to the present deepening of the continental margin. For this reason, the initial extension that triggered the breakup of Gondwana and the opening of the South Atlantic has been well preserved in the South American margin, as opposed to their conjugate counterpart along the African margin. The structural framework described in this contribution and the potential presence of Paleozoic pre-rift source rocks provide appealing exploratory alternatives for sourcing, migration and trapping of hydrocarbons.

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El Bolsón Pagancillo (La Rioja, Argentina), Una Fosa Tectónica Constrictiva en un Ambiente Subandino y su Relación con el Lineamiento de Valle Fértil [PAPER IN SPANISH] El Bolsón Pagancillo (La Rioja, Argentina), a Rift Valley into a Constrictive Sub And

Eduardo A. Rossello Marcos E. Mozetic P.R. Cobbold Oscar R. López-Gamundí

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Source Versus Depositional Controls on Sandstone Composition in a Foreland Basin: The El Imperial Formation (Mid Carboniferous-Lower Permian), San Rafael Basin, Western Argentina

Journal of Sedimentary Research (1994)

Irene S. Espejo Oscar R. López-Gamundí

ABSTRACT The El Imperial Formation (mid-Carboniferous-Lower Permian) constitutes a progradational sandstone-rich succession deposited in the San Rafael foreland basin of western Argentina. Four facies associations have been identified: a basal glacial marine association, a shallow marine association, a deltaic association, and an uppermost fluvial association. Sand-prone deposits in the deltaic association are represented by prodelta and delta-front shales and subordinate fine sandstones (Facies A), deltaic platform, wave-reworked channel mouth-bar sandstones (Facies B), and fluvial-dominated distributary channel sandstones (Facies C). Analysis of framework grains of sandstone samples from Facies B and C shows two distinct mineral assemblages or petrofacies. The quartzose petrofacies is characterized by high contents of quartz and low percentages of feldspar and lithic grains. The quartzolithic petrofacies shows an increase in labile components, in particular lithic fragments, and a concomitant decrease in quartz. The quartzolithic petrofacies shows a source signature. Average detrital modes of sandstones from this petrofacies are similar to those from overlying fluvial sandstones. All wave-reworked, channel mouth-bar sandstones (Facies B) correspond compositionally to the quartzose petrofacies, whereas detrital modes from the distributary-channel sandstones (Facies C) fall into the quartzolithic petrofacies. This correspondence between depositional environment and petrofacies suggests a strong depositional influence on composition (depositional signature). Abrasion (mechanical breakdown) by wave action in shallow marine environments accounts for the quartz-rich nature and paucity of labile grains in the quartzose petrofacies.

10.1306/d4267cee-2b26-11d7-8648000102c1865d

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Sedimentation styles and variability of organic matter types in the Triassic, non-marine half-grabens of west Argentina: implications for petroleum systems in rift basins

Petroleum Geoscience (2010)

Oscar R. López-Gamundí

ABSTRACT Extensional relaxation due to the collapse of the active margin of Gondwanaland during the Triassic led to rapidly subsiding, fault-bounded half-grabens in west Argentina. The Cuyo rift basin was the largest of these fault-bounded troughs. Two linked asymmetrical half-grabens have been identified in the Cuyo basin: Cacheuta in the south and Las Penas-Tamberias in the north. Their stratigraphy exhibits a classic tripartite internal organization with a basal alluvial and fluvial section followed by a lacustrine interval which in turn is overlain by fluvial deposits. The basin fill in both half-grabens shows significant lateral thickness variations that reflect the contrasting subsidence rates on the fault and flexural margins. The lacustrine shales in the Cacheuta half-graben have an average total organic carbon (TOC) content of 4%, locally reaching 20%, dominated by type I, amorphous, algal organic matter and high hydrogen index (HI) values. The shales are associated with parasequences in river-dominated deltas. Oils derived from these source rocks are waxy and with low sulphur content. The oil shales are associated with sandstones arranged in parasequences deposited in river-dominated Gilbert-type deltas. This interval in the Cacheuta half-graben can be assigned to a slightly overfilled to balanced-fill lake type. In Las Penas-Tamberias, the dominant source rock facies in the lacustrine section is made up of calcareous shales with oil-prone, type I(II) kerogen and TOC values up to 13% and high HI values. The presence of gammacerane and b-carotane, common in saline conditions, is conspicuous. The presence of oolitic and bioclastic grainstones and microstromatolitic limestones on the ramp margin and clastic facies on the border fault suggests a slightly underbalanced to balanced lake type. The Cuyo rift basin branches to the NE into the Ischigualasto-Villa Union half-graben. Lacustrine shales along the fault margin of this half-graben are dominated by type III, gas-prone organic matter with TOC values up to 4% and low HI values. Parasequences with a strong progradational stacking pattern and steep front slopes are interpreted as mouth bars in a Gilbert-type delta. These characteristics are consistent with an overfilled lake basin type where sedimentation rate exceeds subsidence rate. The Triassic rift system of west Argentina shows the gamut of lacustrine source rocks that, combined with the analysis of diagnostic associated facies, allow the discrimination of lake basin types and their influence in the resulting hydrocarbon phase.

Petroleum exploration

Sedimentation

Petroleum geology

Geobiology

10.1144/1354-079309-912

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Giant Mass Transport Complex from the Distal Magdalena Fan, Offshore Colombia :Seismic Characterization

11th Simposio Bolivariano - Exploracion Petrolera en las Cuencas Subandinas (2012)

Stephen Leslie Juan Carlos Mosquera Feijóo Ingrid Cordon Oscar R. López-Gamundí

A giant (>3000 km3) mass transport complex (MTC) is imaged from the distal Magdalena Fan, offshore Colombia. The MTC is imaged on a loose grid of 2D seismic data, located in ultra-deep water 150-200 km north of the city of Barranquilla. The deposit varies in thickness from ~40-200 m, thinning onto pre-existing seafloor topography. The area of the slide is >25,000 km2. Calculations indicate a volume larger than 3000 cubic kilometers of sediment was involved in this single catastrophic event. The MTC is likely Pleistocene in age as constrained by the DSDP site 153 well penetration. The top of the deposit is defined by a relatively rugose seismic reflector and lies only 150 m below the present day seafloor. Internally, a variety of seismic facies are present, ranging from incoherent/chaotic within the core of the deposit, to continuous reflections broken by small scale, regular reverse faults at the margins. Little to no erosion appears to have occurred at the base of the deposit, as evidenced by continuous and conformable reflections in the interface between the underlying sediments and the base of the MTC.

Conformable matrix

Seafloor Spreading

10.3997/2214-4609-pdb.330.108

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The Tunas Formation (Permian) in the Sierras Australes foldbelt, east central Argentina: evidence for syntectonic sedimentation in a foreland basin

Journal of South American Earth Sciences (1995)

Oscar R. López-Gamundí Patrick J. Conaghan Eduardo A. Rossello P.R. Cobbold

Massif

10.1016/0895-9811(95)00001-v

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Citations (64)

Geometria de Semi-Graben en las Cuencas Triásicas del Oeste Argentino: Evidencias de Superficie y de Subsuelo

9th Simposio Bolivariano - Exploracion Petrolera en las Cuencas Subandinas (1997)

Oscar R. López-Gamundí Marcos E. Mozetic Eduardo A. Rossello

10.3997/2214-4609-pdb.117.041esp

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Permian plate margin volcanism and tuffs in adjacent basins of west Gondwana: Age constraints and common characteristics

Journal of South American Earth Sciences (2006)

Oscar R. López-Gamundí

10.1016/j.jsames.2006.09.012

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Citations (64)

Southern South America

Memoir - Geological Society of America (1994)

Oscar R. López-Gamundí Irene Espejo Patrick J. Conaghan Christine Powell Judith Veevers

In central-western Argentina, the basement comprises Cambrian to Devonian sedimentary rocks, deformed and uplifted during the Late Devonian-earliest Carboniferous Chañic orogeny along the Paleo-Pacific margin of South America. Unconformably above basement, the Gondwana cycle comprises two unconformity-bounded sequences. The Visean (350 Ma) to earliest Permian (275 Ma) Lower Sequence started with deposition in the Andean (or western) Calingasta-Uspallata Basin of valley-fill sediments. By the Namurian, alpine glaciation of a basement ridge, the Proto-Precordillera, fed sediment into the marine Calingasta-Uspallata Basin on the west and the nonmarine western Paganzo Basin on the east. The Paganzo Basin received additional sediment shed from...

Devonian

Basement

Viséan

Orogeny

10.1130/mem184-p281

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Citations (118)