Repositorio Digital Sernageomin
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Evidencias de remoción en masa en el km 225 de la ruta 41CH, sector Paso Agua Negra, región de Coquimbo
Get PDFRevisores: Alejandro Alfaro S. y Carolina Jara I. -- Informe Técnico17 p
Evaluación de peligro geológico en el sector Las Vertientes, ruta costera T-352, comuna de Valdivia, región de Los Ríos
No full textRevisor: Alejandro Alfaro y Constanza Hoffmann ; Código de identificación interno: INF-LOS RÍOS-01.2022.21 p
Evaluación geológica de puntos de encuentro transitorio en las comunas de Pinto, Coihueco y San Fabián en caso de erupción del complejo volcánico Nevados de Chillán, región del Ñuble
No full textInforme Técnico -- Unidad Ejecutora: Unidad de Geología y Peligros de Sistemas Volcánicos, Santiago88 p
Historical photographs by South African geologist Alexander L. du Toit taken along the Transandine Railway (Argentina-Chile) in 1923
No full textSouth African geologist Alexander du Toit spent three months in 1923 doing reconnaissance mapping in South America, which resulted in his seminal 1927 work “A Geological Comparison of South America and South Africa”. A few photographs taken by du Toit were published, but most were destroyed in a devasting fire in April 2021. Some surviving annotated images, giving locations, of a trip du Toit had made from Argentina to Chile on the Transandine Railway, in 1923, are reproduced here. They may help with recognizing landscape changes, such as due to melting glaciers, during the century since the photographs were taken.pp.288-29
The first fossil record of a giant horsetail (Equisetum, Equisetaceae) is from the Miocene of Patagonia, Argentina
No full textA Miocene macroflora recovered from Ñirihuau Formation sediments exposed at Quebrada Vera site in northwesterern Patagonia, Argentina, is recorded and described for the first time. The assemblage is composed exclusively of free-sporing plants, mainly by Equisetum remains with subordinate occurrences of four fern morphotypes (represented by bi-, tri- and pinnate fronds). Equisetum imprints and molds include distinctive jointed stems with whorls of linear and basally fused leaves, numerous scars of lateral branches arranged in a radially symmetrical pattern situated at the nodes, and nodal diaphragms of up to 4 cm in diameter. The large size and regular branching of the stems link the fossils to the South American giant members of the genus and they probably represent a new fossil species. This is the first conclusive fossil record of a giant Equisetum worldwide, and consequently, it is biogeographically and evolutionarily relevant. The new findings attest that members of the giant horsetail clade were components of the Patagonian vegetation in the Miocene, implying that the age of the clade must predate that estimated from morphological and/or molecular data. The plant fossil assemblage represents part of a wetland community probably growing close to a riverside or lakeshore in coincidence with previous sedimentological estimates.pp.273-28
Reporte de visita técnica por amenaza de remociones en masa, Comuna de Chiguayante del Gran Concepción, Región del Biobío
No full text10 p
Visita Técnica por deslizamiento en ruta O-60 hacia Chiguayante, Provincia de Concepción, Región del Biobío
No full textRevisor: Carolina Jara ; Informe Técnico17 p
Visita Técnica por avalancha de roca y suelo en el Parque Nacional Torres del Paine, comuna de Torres del Paine, provincia de Última Esperanza, región de Magallanes y Antártica Chilena
No full textRevisor: Carolina Jara. -- Informe Técnico -- Unidad Ejecutora: Unidad de Asistencias Técnicas y Emergencias Geológicas, Santiago16 p
Visita técnica a sectores de la comuna de Lebu, región del Biobío, afectados por remociones en masa durante el mes de Julio del año 2022
No full textRevisores: Monica Marin y Carolina Jara -- Informe Técnico16 p
Eocene mammals from volcaniclastic deposits of the Somun Cura Plateau : Biostratigraphic implications for north Patagonia Paleogene
No full textThe Paleogene terrestrial faunal succession and its associated bearing volcaniclastic deposits has been exhaustively studied in central Patagonia, but there is still no acceptable litho-bio-chronostratigraphic ordering for the extra-Andean North Patagonia. The only references on Paleogene mammals bearing deposits north to Chubut River are imprecise and contradictory. West to Ingeniero Jacobacci (Río Negro Province, Argentina), the paleontologist and archaeologist Rodolfo Casamiquela reported a fossiliferous succession with Casamayoran or Mustersan (Eocene) and Deseadan (Oligocene) mammals from rocks currently mapped as the Las Chacras Formation. This unit includes acid to intermediate tuffs, ignimbrites, paleosols, conglomerates, and basalts originated in a perivolcanic fluvial system, under a seasonal subhumid-humid climate according to predominant pedogenic features. As a result of our fieldworks and fossil collection in the area of Ingeniero Jacobacci, and the revision of the materials collected by Casamiquela in the forties and fifties (with well-known stratigraphic origin), we identified a single mammal association from the lower section of the Las Chacras Formation (here named the Lower Las Chacras fauna) composed by: Plesiofelis schlosseri Roth, 1903 (Sparassodonta), Trigonostylops Ameghino, 1897, Astraponotus Ameghino, 1901 (Astrapotheria), Propyrotherium Ameghino, 1901 (Pyrotheria), Pseudhyrax eutrachytheroides Ameghino, 1901, Eohegetotherium priscum Ameghino, 1901, Puelia sigma (Ameghino, 1901), Periphragnis Roth, 1899 (Notoungulata), Isutaetus depictus Ameghino, 1902 (Cingulata), and a new member of Adianthidae (Litopterna) and probably of Pichipilidae (Paucituberculata). This assemblage is closer to that derived from the Rosado Member of the Sarmiento Formation at Gran Barranca, central Patagonia (type locality of the Mustersan Land Mammal Age) dated in ca. 38 Ma (late middle Eocene). A pyroclastic flow associated to the bearing deposits of Ingeniero Jacobacci was dated (K-Ar) in 39.2±2 Ma, value compatible with the Mustersan age here inferred for the Lower Las Chacras fauna. The alleged occurrence of Deseadan mammals in these levels was based on remains of an isotemnid notoungulate incorrectly identified as a leontinid. The presence of the Tinguirirican (early Oligocene) notoungulate Eohegetotherium priscum, with more apomorphic dental traits than in its Eocene allies, and of an astrapotheriid more derived than Astraponotus suggests that some advanced faunal elements would have been established in North Patagonia earlier than in central Patagonia.pp.238-27