Provenance of the Ciénaga de Oro Formation: unveiling the tectonic evolution of the Colombian Caribbean margin during the Oligocene - Early Miocene

Se realizó el estudio de una sección estratigráfica en el Cinturón Plegado y de Cabalgamiento de San Jacinto, localizado en el noroccidente de Colombia. En esta sección aflora parte de la Formación Ciénaga de Oro del Oligoceno-Mioceno temprano. Este trabajo analiza la procedencia de los sedimentos, utilizando un enfoque de múltiples herramientas que incluye: (I) conteo de clastos de areniscas y conglomerados con malla, (II) minerales pesados, y (III) paleocorrientes y (IV) edades U-Pb de circones detríticos. La secuencia sedimentaria fue depositada en un ambiente deltaico a transicional, con reducción del efecto del oleaje y la marea junto con el incremento de la dominancia de los procesos transicionales de río hacia el tope de la sección. Se identificó dos áreas fuentes de una provincia de arco disectado: principalmente un área fuente de composición granítica a pegmatítica y un área fuente secundaria de composición ígnea a básica, localizadas al este y suroeste de la posición actual de la secuencia. El análisis geocronológico de circones detríticos muestra cuatro poblaciones de edades: (I) Devónico-Pérmico, (II) Pérmico-Triásico, (III) Jurásico y (IV) Cretácico. Las edades máximas de depositación corresponden a 75,2±0,9 Ma en la parte más baja de la sección, 68,9±0,6 Ma en el medio y 74,5±0,7 Ma para la parte superior de la sección. Se propone que el material depositado en COF fue suministrado desde sistemas fluviales del sur hacia el norte, que erosionaron bloques de basamento expuesto y su cobertura sedimentaria (Cretácico tardío a Paleógena) durante el Oligoceno. Este sistema fluvial transportó sedimentos desde plutones tipo Batolito Antioqueño del Cretácico Tardío y rocas máficas/ultramáficas, como las encontradas en las Cordillera Central y Occidental.A stratigraphic section in the San Jacinto fold and thrust belt located at northwestern Colombia was studied. This section displays part of the Oligocene-Early Miocene Ciénaga de Oro Formation (COF). This work analyses the sediments provenance using a multi-tool approach which include: (I) conglomerate and sandstone counting clast with mesh, (II) heavy minerals assemblages, (III) paleocurrents and (IV) U/Pb detrital zircon ages. The sedimentary sequence was deposited in deltaic to transitional environment deposition, with reduction in the waves and tidal effect, and increase in the dominance of transitional river processes upward the section. Two main source areas have been identified from a dissected arc province: a main granitic to pegmatitic and a secondary basic igneous source rocks, located to the east and southwest of the current position. Detrital zircon U-Pb geochronology analysis display four age populations: (I) Devonian-Permian, (II) Permian-Triassic, (III) Jurassic and (IV) Cretaceous, with maximum deposition ages of 75.2±0.9 Ma in the lower part of the section, 68.9±0.6 Ma in the middle and 74.5±0.7 Ma for the upper part. It is proposed that COF was sediment-supplied by a south-to-north flvial system, which drained exposed basement blocks and their late Cretaceous to Paleogene sedimentary cover during the Oligocene. This fluvial system carried sediments from late Cretaceous plutons like the Antioqueño Batholith and mafi/ultramafi rocks, which make up the basement of the Western and Central Cordilleras

CRE Dating of Torrential Alluvial Deposits as an Approximation to Holocene Climate-Change Signatures in the Northwestern Andes of Colombia

International audienc

Erosion rates and morphogenesis of the El Peñol de Guatapé inselberg, northern Andes (Colombia), inferred from geomorphic analyses and cosmogenic 10Be measurements

International audienc

Thermochronological, petrographic and geochemical characteristics of the Combia Formation, Amagá basin, Colombia

The Amagá basin between the Western and Central Cordilleras of the Northern Andes of Colombia hosts the Neogene volcanic and volcaniclastic Combia Formation. Deposition of the Combia Formation in relation to Nazca plate subduction and arc volcanism is still a matter of debate. Therefore, the timing, petrography and geochemical characteristics of Combia Formation rocks were studied in the western and eastern parts of the Amagá basin, in order to gain more information on the type of magma generation and volcanic activity that led to the deposition of the Combia Formation. Apatite and zircon fission-track dating largely confirm a 12-6 Ma age for the deposition of the Combia Formation. Petrographic and major element analyses show that mainly trachy-andesite ignimbrites with a calc-alkaline composition were deposited in the western Amagá basin, whereas the volcanic rocks of the eastern Amagá basin are lavas flow and fall-out deposits of basaltic andesites of tholeiitic affinity. Trace element and isotopic analyses show that slab dehydration and sediment melting/decarbonation were important in primary magma generation in the mantle wedge, but the primary magma was mixed with lower continental crustal melts (e.g. High-Pb radiogenic), resulting in characteristic isotope signatures in the western and eastern Amagá basin. Then, the hot-zone developed a high Pb-radiogenic, garnet-bearing lower continental crustal (LCC) level as a consequence of the quantity of dehydration of the subducting slab and of changes in the tectonic regime. An extensional pull-apart event (12- 9 Ma), likely facilitated rapid magma ascend to the uppermost crust along a subvertical magma plumbing system throughout the Romeral Fault zone in the eastern Amagá basin, and calc-alkaline magmas with adakite-like signature, which may indicate contractile tectonics that allow the formation of middle-to upper-crustal magma chambers with a garnet fractionation at depth and the evolution of silicate melts into the hot zone mainly related to the amount of water (>4 wt %) present. © 2020 Elsevier Lt

Biodiversidad 2017. Estado y tendencias de la biodiversidad continental de Colombia

En la cuarta versión del Reporte, que corresponde al año 2017, es una obligación preguntarnos cuál ha sido y es el papel de esta publicación y si ha abarcado la diversidad de formas y conceptos que definen el estado y el futuro de la biodiversidad colombiana. Las temáticas que constituyen la columna vertebral de cada uno de los reportes anuales responden a temas de pertinencia, nivel de incidencia y actualidad desde cada uno de los diferentes niveles de organización de la biodiversidad y buscan responder las siguientes preguntas fundamentales: 1) ¿Cómo se encuentra la biodiversidad del país? 2)¿Qué factores, en dónde y en qué medida está siendo afectada? 3)¿Cuáles son las iniciativas que desde la sociedad civil o a nivel de políticas públicas buscan evitar esa pérdida? 4)¿Cuáles son las grandes oportunidades para mejorar su gestión y manejo? Si bien evaluar la incidencia que puede tener el Reporte sobre acciones de gestión no es tarea fácil, se debe reconocer la buena acogida que han tenido los textos, las ilustraciones y la cifras entre los distintos tipos de lectores y el papel fundamental que ha jugado el Reporte en comunicar información de altísima calidad sobre la biodiversidad colombiana en diferentes momentos coyunturales. En ese sentido esta publicación es cada vez más una herramienta de consulta y referencia que está abierta al público tanto en formato impreso como digital, y de la misma manera busca fortalecerse para continuar brindando información relevante para la toma de decisiones en materia ambiental.BogotáSubdirección de Investigacione

Contemporary use of cefazolin for MSSA infective endocarditis: analysis of a national prospective cohort

Objectives: This study aimed to assess the real use of cefazolin for methicillin-susceptible Staphylococcus aureus (MSSA) infective endocarditis (IE) in the Spanish National Endocarditis Database (GAMES) and to compare it with antistaphylococcal penicillin (ASP). Methods: Prospective cohort study with retrospective analysis of a cohort of MSSA IE treated with cloxacillin and/or cefazolin. Outcomes assessed were relapse; intra-hospital, overall, and endocarditis-related mortality; and adverse events. Risk of renal toxicity with each treatment was evaluated separately. Results: We included 631 IE episodes caused by MSSA treated with cloxacillin and/or cefazolin. Antibiotic treatment was cloxacillin, cefazolin, or both in 537 (85%), 57 (9%), and 37 (6%) episodes, respectively. Patients treated with cefazolin had significantly higher rates of comorbidities (median Charlson Index 7, P <0.01) and previous renal failure (57.9%, P <0.01). Patients treated with cloxacillin presented higher rates of septic shock (25%, P = 0.033) and new-onset or worsening renal failure (47.3%, P = 0.024) with significantly higher rates of in-hospital mortality (38.5%, P = 0.017). One-year IE-related mortality and rate of relapses were similar between treatment groups. None of the treatments were identified as risk or protective factors. Conclusion: Our results suggest that cefazolin is a valuable option for the treatment of MSSA IE, without differences in 1-year mortality or relapses compared with cloxacillin, and might be considered equally effective