Gravity, isostasy and Andean crustal shortening between latitudes 30 and 35°S

Introcaso, Antonio; Pacino, María Cristina; Fraga, Hilda Jaqueline de

doi:10.1016/0040-1951(92)90416-4

Cited by 74 publications

(44 citation statements)

References 22 publications

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“…The P wave velocities of the crust, ranging from 6.6 km/s to 5.3 km/s, are obtained from Barrientos et al (2004). The density values are obtained from a 2D Andean crustal gravity-seismic model of Introcaso et al (1992). The average values of density of different rock domain ranges from 2800 kg/m 3 to 2630 kg/m 3 .…”

Section: Rock Domain Propertymentioning

confidence: 99%

Origin of the regional stress field along the Liquine-Ofqui Fault Zone (LOFZ), Southern Chilean Andes by means of FE simulation

Islam

2009

J. Mt. Sci.

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The Liquine-Ofqui Fault Zone (LOFZ) of southern Chilean Andes is one of the largest active strike-slip fault zones. There is an ongoing debate regarding the origin of the stress field along the LOFZ due to its complex geometry. This paper represents a study of the origins of the LOFZ regional stress field. Stress fields are calculated by finite element (FE) analysis. The two possible stress origins, i.e., oblique plate convergence and ridge collision/indenter tectonics of Chile ridge against Peru-Chile trench, have been emphasized in the present study. Three types of boundary conditions for the three particular models have been applied to calculate stress fields. Models are assumed to be elastic and plane stress condition. Modeling results are presented in terms of four parameters, i. e., orientation of maximum horizontal stress ( σ H max ), displacement vector, strain distribution, and maximum shear stress ( τ max ) contour line within the model. The results of the first model with oblique plate convergence show inconsistency between the geometric shape of the LOFZ and the distribution of the four parameters. Although more realistic results are obtained from the second model with normal ridge collision, there are few coincident in the LOFZ geometry and regional stress field. The third model with normal and oblique ridge collision is reasonable in understanding the origin of stress field and geometrical condition in the lithosphere of the LOFZ.

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Section: Rock Domain Propertymentioning

confidence: 99%

Origin of the regional stress field along the Liquine-Ofqui Fault Zone (LOFZ), Southern Chilean Andes by means of FE simulation

Islam

2009

J. Mt. Sci.

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“…A constant V p /V s ratio of 1.74 was chosen from Graeber and Asch (1999). The density values were taken from Introcaso et al (1992). The average values of density of different rock layers ranged from 2,680 kg/m 3 to 2,800 kg/m 3 .…”

Section: Materials Parametersmentioning

confidence: 99%

“…The calculated Poisson's ratio was 0.25, while equ.2 (Christensen 1996) was used. The Pwave velocities within the Andean crust ranged from 7.20 km/s to 5.0 km/s (Introcaso et al 1992). A constant V p /V s ratio of 1.74 was chosen from Graeber and Asch (1999).…”

Section: Materials Parametersmentioning

confidence: 99%

Cohesive strength and seismogenic stress pattern along the active basement faults of the Precordillera-Sierras Pampeanas ranges, western Argentina: An experimental analysis by means of numerical model

Islam

2009

J. Mt. Sci.

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A two-dimensional finite element method (FEM) model that incorporates faults, elastic rock physical properties, topographical load due to gravity and far-field plate velocity boundary conditions was used to recognize the seismogenic stress state along the fold-and-thrust belt of the Precordillera-Sierras Pampeanas ranges of western Argentina. A plane strain model with nine experiments was presented here to examine the fault strength with two major rock phyical properties: cohesion and angle of internal friction. Mohr-Coulomb failure criterion with bulk rock properties were applied to analyse faults. The stress field at any point of the model was assumed to be comprised of gravitational and tectonic components. The analysis was focused to recognize the seismogenic shear strain concentrated in the internal-cristaline domain of the orogene shown by the modeling. Modeling results are presented in terms of four parameters, i. e., (i) distributions, orientations, and magnitudes of principal stresses (σ1 and σ3), (ii) displacement vector, (iii) strain distribution, and (iv) maximum shear stress (τmax) contour line within the model. The simulation results show that the compressive stress is distributed in and around the fault systems. The overall orientation of σ1 is in horizontal directions, although some stress reorientations do occur within weaker parts, especially subsequent to the faults. A large-scale shear stress is accumulating along the active faults of Tapias-Villicum Fault (TVF), Salinas-Berros Fault (SBF), Ampacama-Niquizanga Fault (ANF) and Las Charas Fault (CF), which could act as local stress and strain modulators to localize the earthquakes occurrence.

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“…Tal como fuera mencionado anteriormente, para el inicio de la depositación del Grupo Neuquén la Cuenca Neuquina habría comenzado a operar como una cuenca de antepaís; producto de una tectónica compresional que posibilitó el desarrollo de una faja plegada y corrida sobre el sector occidental, asociada a un acortamiento cortical de 45 a 57 km (Introcaso et al, 1992;Ramos, 1999ª;Franzese et al, 2003;Howell et al, 2005). Los mapas de curvas isopáquicas elaborados por Cazau & Uliana (1973) y Uliana et al (1975b) para los depósitos del Grupo Neuquén, muestran la existencia de depocentros elongados meridionalmente y recostados sobre el área occidental de la cuenca, denotando una relación de paralelismo y adyacencia a la faja de deformación.…”

Section: Contexto Paleogeográficounclassified

Taxonomic and stratigraphic revision of Lower Cretaceous cicatricose spores from Patagonia. 2. Genera Cicatricosisporites Potonié & Gelletich and Ruffordiaspora Dettmann & Clifford

Archangelsky¹,

Archangelsky²

2010

MACN

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Stratigraphy of the Neuquén Group, Upper Cretaceous of the Neuquén Basin (Argentina): new proposal for lithostratigraphic ordaining. The Neuquén Group conform a succession of non-marine deposits of fluvial, aeolian and shallow lacustrine origin, developed in the Neuquén Basin between the Lower Cenomanian and the Middle Campanian (Upper Cretaceous). This succession reaches 1,200 m of maximum thick, being bounded at the base and the top by the Patagonidican and Huantraiquican unconformities respectively. In this paper two new formations are proposed (Los Bastos and Sierra Barrosa Formations, nom. nov.), and the subgroups were reconfigurated. Consequently, the Neuquén Group is composed lithostratigraphically by three subgroups and nine formations. The Río Limay Subgroup comprehend the Candeleros and Huincul Formations, representing low sinuosity channel deposits developed under tectonic and climatic subordinated control. The Río Neuquén Subgroup comprehend to the Cerro Lisandro, Portezuelo, Los Bastos, Sierra Barrosa and Plottier Formations, conforming a psamitic and pelitic interstratified succession of fluvial origin, mainly developed under climatic control. Finally, the Río Colorado Subgroup integrated by the Bajo de la Carpa and Anacleto Formations, comprehend fluvial deposits developed under a new dominant tectonic control. At the start of the deposition of the Neuquén Group, the Dorsal de Huincul worked as a structural high, generating toward the south of the Neuquén Basin one a small endorreic depocentre corresponding to the Picún Leufú Sub-basin, scheme that would have been keep up to ends of the deposit of the Candeleros Formation. During the rest of the deposit of this sequence, the drainage would have been kept without major modifications towards the pacific slope across a central collector flowing in sense N-NW. Towards the end of the deposit of the Neuquén Group takes place the inversion of the regional slope of the basin, making possible the ingression of the Atlantic Ocean and the beginning of the deposition of the Malargüe Group.Key words: Neuquén Group, new lithostratigraphic units, Upper Cretaceous, Neuquén Basin, Argentina.Resumen: El Grupo Neuquén conforma una sucesión de depósitos continentales de origen fluvial, eólico y lacustre somero, desarrollado en la Cuenca Neuquina entre el Cenomaniano Inferior y el Campaniano Medio (Cretácico Superior). Esta sucesión alcanza un espesor máximo de 1.200 m, encontrándose limitada en base y techo por las discordancias Patagonídica y Huantráiquica respectivamente. En este trabajo se proponen dos nuevas formaciones (Formación Los Bastos nom. nov. y Formación Sierra Barrosa, nom. nov.) y los subgrupos fueron reconfigurados. Consecuentemente, el Grupo Neuquén queda compuesto litoestratigráficamente por tres subgrupos y nueve formaciones. El Subgrupo Río Limay comprende a las Fms. Candeleros y Huincul, representando a depósitos de canales de baja sinuosidad desarrolladas bajo un control tectónico y climático subordinado. El Subgrupo Río Neuquén compre...

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Gravity, isostasy and Andean crustal shortening between latitudes 30 and 35°S

Cited by 74 publications

References 22 publications

Origin of the regional stress field along the Liquine-Ofqui Fault Zone (LOFZ), Southern Chilean Andes by means of FE simulation

Origin of the regional stress field along the Liquine-Ofqui Fault Zone (LOFZ), Southern Chilean Andes by means of FE simulation

Cohesive strength and seismogenic stress pattern along the active basement faults of the Precordillera-Sierras Pampeanas ranges, western Argentina: An experimental analysis by means of numerical model

Taxonomic and stratigraphic revision of Lower Cretaceous cicatricose spores from Patagonia. 2. Genera Cicatricosisporites Potonié & Gelletich and Ruffordiaspora Dettmann & Clifford

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