Repositorio Digital Sernageomin
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Evaluación por remoción en masa en km 5,7 sector El Arenal, comuna de Coyhaique, región de Aysén del General Carlos Ibáñez del Campo
No full textInforme Técnico -- Unidad Ejecutora: Dirección Regional de Aysén12 p
Conjugate Riedel shears in a volcanic caldera : The case of the Laguna del Maule Volcanic Complex, Central Chile
Full text linkThe Andean intra-arc is characterized by large-scale continuous lineaments, often the direct surface expression of tectonic structures. In this study, we analyze the main lineaments around the Laguna del Maule Volcanic Complex, Central Chile (~36° S), to shed light on the main tectonic processes. We show that the lineament directions are consistent with structures based on a theoretical Riedel model and suggest the occurrence of two conjugate Riedel shears crossing Laguna del Maule. This structural arrangement can accommodate deformation related to either a transtensional regime, having a WNW-oriented master fault (Laguna Fea Fault), or a transpressional regime, characterized by NNE-oriented master faults (e.g., Melado Fault). In this context, the NE-striking Troncoso Fault would be a long-lived dextral fault compatible with both regimes. According to the Riedel model, ENE-oriented lineaments are predicted to be tensional structures, whilst NW-oriented structures (e.g., Los Cóndores Fault) would correspond to P-type structures accommodating compressional deformation. This tectonic architecture, characterized by the most intense deformation just at the intersection between shears, has likely promoted magma accumulation and would explain the compositional variability at Laguna del Maule. This study therefore demonstrates the usefulness of oriented lineament maps in interpreting regional tectonics for volcanically active areas.pp.460-47
Potencial geológico de minerales críticos y/o estratégicos en Chile
No full textInforme Registrado IR-24-119108 p
Evaluación geológica de puntos de encuentro transitorio en la comuna de Alto Biobío en caso de erupción del Volcán Callaqui, región del Biobío
No full textInforme Técnico -- Unidad Ejecutora: Unidad de Geología y Peligros de Sistemas Volcánicos, Santiago98 p
Tracing magmatic footprints : Influence of a CO2-rich melt on the mineral assemblage of the San José del Guaviare Syenite, SE Colombia
No full textA combined optical and electron microscopy (SEM, EDS, and EPMA) study was conducted on ten rock samples from the Proterozoic San José del Guaviare Syenite (SJGS), southeastern Colombia, to utilize minor and trace minerals in interpreting the magmatic evolution of these silica undersaturated rocks. The major minerals of the sampled syenites are nepheline, Fe-rich clinopyroxene, amphibole, alkali feldspar, and biotite. The minor minerals are titanite, calcite, cancrinite, and sodalite. Trace minerals are the niobium- or rare earth element-rich minerals pyrochlore, columbite, euxenite, britholite, ancylite-Ce and wöhlerite. Apatite, rhodochrosite, strontianite, fluorite, zircon, magnetite, ilmenite, and pyrite occur as traces as well.Crystallization started with primary (magmatic) calcite and Nb-rich minerals pyrochlore, columbite, euxenite, and a first generation of apatite, which occur as inclusions in foids, feldspars, and Fe-rich clinopyroxenes. Calcite is enriched in light rare earth elements and Sr, with low Mg concentrations, while primary apatite has high Sr concentrations. Both minerals have a composition typical for minerals crystallized in carbonatites. The presence of calcite and high Fe and low Ti clinopyroxene point to CO2-saturated conditions.During cooling, fluorbritholite-Ce formed as individual grains or by a fluid-enhanced apatite-britholite transformation. The formation of Fe-rich amphibole, often at the expense of Fe-rich clinopyroxene, reveals a decreasing influence of CO2 and temperature. Presumably, the transformation of orthoclase into microcline occurred simultaneously. Perthitic microcline as a second K-feldspar generation indicates slow cooling from high temperatures. A late stage of CO2-rich hydrothermal-metasomatic processes is suggested by the growth of secondary cancrinite, Sr-Mn carbonates and ancylite-Ce.The composition of primary and early crystallized calcite and apatite makes their origin as residues of an early segregated or independently formed mantle-derived carbonatitic melt more likely than crystallization from a CO2-rich syenitic melt. An origin from melted crustal carbonates is unlikely as well. Therefore, the presence of a carbonatitic melt at an early magmatic evolutive stage, as opposed to a non-carbonatitic melt at a late stage, seems possible for the SJGS rocks.pp.425-45
The Andean Southern Volcanic Zone : A review on the legacy of the latest volcanic eruptions
No full textThe Andean Southern Volcanic Zone (SVZ) concentrates many of the most active volcanoes of the Andean continental arc, as well as the region’s most recent and impactful volcanic eruptions. In this contribution, we briefly revise the general characteristics of the SVZ volcanism and provide a synthesis of the scientific findings related to the latest volcanic eruptions (430 peer-reviewed publications with over 9,000 citations, with large-magnitude (VEI 4-5) eruptions being the most studied. Our study shows that SVZ research has been primarily focused on environmental and atmospheric impacts (29%), eruption descriptions and physical volcanology (20%), volcanic hazard and risk assessments (15%), and other investigations complementary to volcanology. Whereas the least silicic eruptions (e.g., Llaima 2008-2009 and Villarrica 2015) shed light on magma replenishment and degassing dynamics controlling eruption styles, intermediate eruptions (andesitic-dacitic) offered clues on either rapid or slow eruption initiation, with relevant findings on phreatic-to-magmatic style transitions and eruption triggering mechanisms. On the other hand, silicic (i.e., rhyolite-rhyodacite) eruptions provided unique observations on rapid magma ascent, high-rate magma extrusion, rheology, fragmentation processes, and style transitions. These recent eruptions have also inspired a new generation of tephrochronological, tephrostratigraphical, and physical volcanology studies, aimed at assessing the long-term (kyr-scale) evolution of the volcanic systems and their associated hazards. We debate how the knowledge gained from research and the long-term human coexistence with volcanoes are relevant to reducing volcanic risk in the SVZ. Finally, we discuss how challenges and opportunities emerging from other disciplines can complement our understanding of volcanism in this active region.pp.379-41
Remociones en masa detonadas por precipitaciones durante agosto y septiembre de 2023, comunas de Tomé, Talcahuano y Hualpén, Gran Concepción, Biobío
Full text linkInforme Técnico -- Unidad Ejecutora: Asistencias Técnicas y Emergencias Geológicas , Dirección Regional Sur. Concepción50 p
Evaluación de peligro de remoción en masa en sector Altos de Cutipay, Loteo Cutipay 1, Niebla, Valdivia, región de Los Ríos
No full textInforme Técnico -- Unidad Ejecutora: Dirección Regional de Los Ríos, Valdivia30 p
Evaluación de peligro de remoción en masa en un tramo de la ruta T-577, sector Chabranco, comuna de Futrono, región de Los Ríos
No full textInforme Técnico -- Unidad Ejecutora: Dirección Regional de Los Ríos, Valdivia17 p