Repositorio Digital Sernageomin
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Geochronology of the Cordillera Real granitoids, the inner magmatic arc of Bolivia
No full textThe Cordillera Real granitoids are a suite of Triassic and Oligocene plutons in the core of the Eastern Cordillera of the Central Andes of Bolivia. Their tectonic setting, chemical and ore compositions make them part of the so-called "Inner Magmatic Arc", which differs from the current "Magmatic Arc" located immediately to the west. U-Pb SHRIMP data were obtained in order to constrain crystallization ages. The Triassic group yielded the following results: 239±2 Ma for the Huato granite, 231±1 Ma for the Illampu granodiorite, 221±3 Ma for the Huayna Potosí granite and 223±2 Ma for the Taquesi granodiorite. For the Oligocene group we obtained ages of 27 Ma for two samples of the Quimsa Cruz granite. Secondary processes related to regional thermal anomalies and magmatic melt-enrichment, reset the K-Ar and U-Pb isotopic systems, producing: a) younger ages by Ar loss and b) anomalous data plot in the Concordia diagram by reorganization of U-Pb isotopic ratios. As noted in previous studies, most zircon analysed from the Zongo/Kuticucho Triassic granite exhibited extremely high U enrichment, producing reverse discordia curves that obscure the true crystallization age. Relatively abundant zircon inheritance was found in these "cold" granitoids, with ages suggesting provenance from early Paleozoic metapelites that also contained recycled older sources. This relatively abundant xenocrystic inheritance probably records the influence of the subduction process acting during the Gondwanide orogeny (336-205 Ma) as an overall subduction arc environment, punctuated at its final stage with the imprint of a continental rifting (245-220 Ma).pp.403-44
Reporte de visita técnica : Posta de salud rural sector El Poncho, comuna de Puerto Octay, región de Los Lagos
No full textInforme Técnico -- Unidad Ejecutora: Oficina Técnica Puerto Varas6 p
Levantamiento electromagnético Z-Axis Tipper (ZTEM) para evaluaciones geotérmicas en cinco zonas del sur de Chile
Get PDFInforme Registrado IR-21-96 ; Contiene Anexos: Anexo I.Procesamiento de los datos ; Anexo II.Estructuras de las bases de datos y resultados: formatos y nomenclaturas ; Base de datos (1 DVD) ; Mapa 1: Resistividad eléctrica del área de Pelehue, región de La Araucanía, Escala 1:50.000 ; Mapa 2: Resistividad eléctrica del área de Manzanar-Sierra Nevada, región de La Araucanía, Escala 1:50.000 ; Mapa 3: Resistividad eléctrica del área de Cupío-Chihuío, región de Los Ríos, Escala 1:50.000 ; Mapa 4: Resistividad eléctrica del área de Puyehue, región de Los Lagos, Escala 1:100.000 ; Mapa 5: Resistividad eléctrica del área de Villarrica, regiones de La Araucanía y Los Ríos, Escala 1:50.00099 p
Estratigrafía del Cretácico Superior entre los 28,5 y los 30° S, regiones de Atacama y Coquimbo
No full textInforme Registrado IR-21-90 ; Contiene Anexos: I.Resumen de edades U-Pb en circón realizadas en este trabajo ; II.Diagramas de concordia e histogramas de frecuencia de edades U-Pb33 p
Estudio geofísico de la cuenca del río Pudeto, región de Los Lagos
No full textInforme Registrado IR-21-93 ; Contiene: Anexo I.Modelos unidimensionales de capas de las estaciones TEM65 p
Potencial de litio en el salar de Las Parinas, región de Atacama, Chile
No full textInforme Registrado IR-21-94 ; Contiene: Anexos I.Listado de concesiones mineras de explotación ; II.Composición química de muestras de costras ; III.Composición química de muestras de salmueras ;
IV.Composición mineralógica de muestras de costras obtenida por DRX ; V.Diagrama de Piper88 p
Reporte de visita técnica: Sector Laguna Foitzick, comuna de Coyhaique, región de Aysén del General Carlos Ibáñez del Campo
Get PDFRevisor: Alejandro Alfaro.4 p
Evaluación de peligro por remoción en masa en proyecto inmobiliario, Sector Playa de Los Enamorados, Niebla, comuna de Valdivia, región de Los Ríos
No full textRevisor: Paola Ramírez ; Código de identificación interno: INF-LOS RÍOS-08.202115 p
Geología del área San Fernando-Curicó, regiones del Libertador General Bernardo O'Higgins y del Maule
No full textInforme Registrado IR-21-89 ; Contiene Anexos: I.Dataciones radiométricas ; II.Fósiles ; III.Yacimientos ; IV.Análisis químicos de rocas; Mapa geológico del área San Fernando-Curicó, regiones del Libertador Bernardo O'Higgins y del Maule, escala 1:100.000 ; Coordenadas: 34°30'S - 35°S / 70°45'O - 71°15'O56 p
The likely Quaternary active El Arrayán fault, Santiago, Chile
No full textUnderstanding the location and nature of Quaternary active crustal faults is critical to the reduction of both fault rupture and strong ground motions hazards in built environments. Recent work along the San Ramón Fault (SRF) demonstrates that crustal seismic sources are important hazards within the Santiago Metropolitan region of Chile. In this paper, we present the evidence of a second likely Quaternary active fault (the El Arrayán Fault, EAF) that runs through the northeastern part of Santiago, in the Lo Barnechea area. The EAF is a strike-slip fault zone at least 13 kmlong, has a steep dip (mean dip 77º NNE), and a WNW-ESE general trend (~110º) that cuts across folded rocks of the Abanico Formation and Quaternary deposits. Sequences of meter-wide fault rocks in El Arrayán area are coincident with the tectonic geomorphology of the EAF, with fault scarps, deflected streams, saddles, "island hills", sag ponds and linear valleys in the La Dehesa area and coincident with fault strike from the bedrock exposures. Although direct dating is not yet available, fault exposures tied to fault-related tectonic and geomorphic features that crosscut Late-Quaternary morphologies and deposits (including hillslopes, ridges, landslides and alluvial fans), provides strong evidence that the EAF is a Quaternary active and seismogenic crustal fault. Sinistral slickensides and left-lateral deflected streams indicates a left-lateral kinematics (with slight up to the north reverse motion) for the EAF. Due to the location, geometry, kinematics and likely Quaternary activity of the EAF, this structure is interpreted as an arc-oblique transfer zone of the West Andean Thrust (WATS). If the EAF has stick-slip behaviour, it is potentially an important source of fault rupture and strong ground motions and could be responsible for earthquakes up to Mw 6.4 based on earthquake scaling laws and microseismicity observations in and around Santiago. The lack of fault zone avoidance criteria (i.e., do not build in and around active faults) in Chilean law, requires immediate enhanced fault mapping, legislation and the implementation of active fault rupture avoidance areas to reduce the risk associated with active crustal structures in the built environment.pp.529-54