Revista Mexicana De Ciencias Geologicas最新文献

{"title":"Evidencias geológicas, geomorfológicas y geofísicas de deformación asociada a la falla Cerritos y su implicación en el peligro sísmico de Morelia, Michoacán, México","authors":"Diana Cinthia Soria-Caballero, Martha Gabriela Gómez-Vasconcelos, Denis Ramón Avellán, Jélime Aray Castellano, Dulce Gutiérrez-Carmona, Adrián Jiménez-Haro, Magdalena Velázquez-Bucio, Jesús Ávila García, Oscar García, Víctor Hugo Garduño-Monroy","doi":"10.22201/cgeo.20072902e.2021.3.1670","DOIUrl":"https://doi.org/10.22201/cgeo.20072902e.2021.3.1670","url":null,"abstract":"La falla Cerritos pertenece a la porción oeste del Sistema de Fallas Morelia-Acambay, ubicada al suroeste de la ciudad de Morelia, en el estado de Michoacán, México; es una zona con alta densidad de fallas activas con geometrías segmentadas y arreglos en échelon, donde se han desarrollado semi-grabens y grabens de dimensiones variables que inclusive influyen en el alineamiento y distribución del vulcanismo monogenético holocénico. En la superficie, estas fallas afectan unidades litológicas de edades miocénicas hasta suelos modernos. Debido a la peligrosidad sísmica que se ha reportado para algunas de las fallas de Morelia, se realizó un análisis interdisciplinario de la falla Cerritos, que había permanecido poco estudiada hasta la fecha. La falla Cerritos es una falla normal con una ligera componente lateral izquierda, una longitud de 12 km y un relieve topográfico bien definido de 130±5 m (100 m de desplazamiento visible + 30 m de desplazamiento subsuperficial obtenido por el estudio de resistividad invertida). Esta falla muestra un rumbo ENE-OSO (255°) y un echado de 76° hacia el NNO. En un afloramiento de la falla Cerritos, a unos cuantos metros del trazo de falla principal, se identificó una cuña coluvial con abundante materia orgánica, fechada con el método de radiocarbono en 3.37–3.21 cal ka AP. El análisis geológico y geomorfológico de la falla reveló que es una estructura tectónicamente activa, relativamente joven y con índices geomórficos que indican mayor actividad en su sector oriental. El escarpe y la acumulación de sedimentos lacustres en el bloque caído sugieren movimiento activo vertical (levantamiento y subsidencia, respectivamente) a lo largo de esta falla. Los resultados obtenidos mediante los análisis de sísmica de refracción, tomografía de resistividad eléctrica y magnetometría terrestre revelaron la geometría de la falla en profundidad, en donde sobresale la presencia de un plano principal lístrico y una zona de deformación en el bloque caído que se extiende en superficie hasta 75 m desde el pie del escarpe principal. Esta zona de deformación se caracteriza por la formación de anticlinales tipo roll-over y dos grabens de colapso crestal delimitados por estructuras secundarias, los cuales funcionan como depocentros de materiales clásticos y bloques caídos. Finalmente, el análisis de actividad y potencialidad indicó que esta estructura tiene tasas de desplazamiento de 0.03±0.01 mm/año, con desplazamientos verticales promedio de 0.5 m por evento, y un tiempo de recurrencia promedio de 16700 años. La Falla Cerritos tiene la capacidad de producir eventos de ruptura con magnitudes de Mw 6.2 a 6.6 por sí sola, o bien, puede interaccionar en un evento extremo con las fallas adyacentes Morelia y Cointzio, produciendo eventos de ruptura multi-falla con magnitudes de hasta Mw 6.9.","PeriodicalId":49601,"journal":{"name":"Revista Mexicana De Ciencias Geologicas","volume":null,"pages":null},"PeriodicalIF":0.8,"publicationDate":"2021-11-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45518684","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Revisión de datos paleomagnéticos de flujos de lava asociados al Campo Volcánico Michoacán Guanajuato: implicaciones sobre el comportamiento del campo magnético terrestre durante el Plio-Cuaternario","authors":"Ulises Díaz-Ortega, R. García-Ruiz, M. Cervantes-Solano, Avto Goguitchaichvili, Rafael Maciel-Peña, J.Julio Morales-Contreras, Rubén Cejudo-Ruiz","doi":"10.22201/cgeo.20072902e.2021.3.1671","DOIUrl":"https://doi.org/10.22201/cgeo.20072902e.2021.3.1671","url":null,"abstract":"La disponibilidad de edades radiométricas para el Campo Volcánico Michoacán-Guanajuato permite obtener un registro detallado de las variaciones del campo magnético de la Tierra durante los últimos 5 Ma. En el presente trabajo, analizamos 112 direcciones paleomagnéticas confiables respaldadas por igual número de edades radiométricas absolutas. Luego de descartar las polaridades geomagnéticas transicionales siguiendo el criterio de paleolatitudes menores a 45°, se calcularon las direcciones paleomagnéticas medias globales. En términos generales, se observa que la dirección media concuerda, dentro del intervalo de incertidumbres, con las direcciones paleomagnéticas esperadas obtenidas según los polos de referencia Plioceno-Cuaternario. La tasa de variación secular, estimada a través de la dispersión de los polos geomagnéticos virtuales calculados, y la anomalía de inclinación coinciden con los modelos de distribución latitudinal reportados para la latitud de 20° N. Un hallazgo interesante, resultado de esta compilación de direcciones paleomagnéticas, es la posible evidencia de eventos geomagnéticos relativamente cortos o excursiones dentro de los Crones de Matuyama y Brunhes, los cuales pueden ayudar a refinar la escala de tiempo de inestabilidad geomagnética. Además, se presenta una compilación inédita y una descripción minuciosa de más de 1000 aparatos volcánicos realizada por el Dr. Víctor Hugo Garduño Monroy que, sin duda alguna, servirá como una guía para los estudios paleomagnéticos durante las siguientes décadas.","PeriodicalId":49601,"journal":{"name":"Revista Mexicana De Ciencias Geologicas","volume":null,"pages":null},"PeriodicalIF":0.8,"publicationDate":"2021-11-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49571975","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Spherical data validation of rock discontinuities orientation from Drone-derived 3D Point Clouds","authors":"J. Mancera-Alejandrez, Sergio Macías-Medrano, Enrique Villarreal-Rubio, Darío Solano-Rojas","doi":"10.22201/cgeo.20072902e.2021.3.1641","DOIUrl":"https://doi.org/10.22201/cgeo.20072902e.2021.3.1641","url":null,"abstract":"This work presents a methodology for the statistical validation of discontinuity surfaces obtained from point clouds using digital photogrammetry from drones. Our methodology allows you to review the quality of the data obtained with photogrammetry and decide whether these measurements are representative of the discontinuity surfaces that they analyze. It consists of three steps, the first one being a shape analysis that allows defining which statistical model should be used: Fisher for circularly symmetric clusters or Bingham fits better for axially symmetric clusters. This step also makes the most significant difference to other works since our methodology starts from the premise that not all discontinuity surfaces are flat. Therefore, Fisher parameters do not allow validating data that do not correspond to a plane. \u0000In the second step of the methodology, we calculate the consistency parameters that depend on the statistical model defined in step 1. The parameters are similar for both models; both estimate κ which indicates how much the sample is concentrated around the mean orientation and validates the existence of this and which is the value of the generating angle of a cone with a 95 % confidence limit that it contains within the mean orientation. \u0000Finally, step 3 is used when there are control measurements to compare the point cloud data and define if both samples characterize the same discontinuity surface in the rock mass. \u0000The results obtained on a rock outcrop allowed us to observe that the measurements obtained from the drone faithfully represent the discontinuity surface analyzed when these were compared with the measurements made manually with the compass. Furthermore, the dispersion parameters (","PeriodicalId":49601,"journal":{"name":"Revista Mexicana De Ciencias Geologicas","volume":null,"pages":null},"PeriodicalIF":0.8,"publicationDate":"2021-11-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45965058","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Mobile mud layer underneath the desiccated maar lake of Rincón de Parangueo and insights into its microbial fingerprints","authors":"J. Sánchez-Sánchez, M. Cerca, R. Alcántara-Hernández, J. Aranda-Gómez, D. Carreon-Freyre, C. Lozano-Flores, I. Muñoz-Velasco, G. Levresse, A. Varela-Echavarría","doi":"10.22201/cgeo.20072902e.2021.3.1636","DOIUrl":"https://doi.org/10.22201/cgeo.20072902e.2021.3.1636","url":null,"abstract":"We surveyed a subsurface layer of saturated mobile mud and its microbial fingerprints below the desiccated bottom of a maar lake at Rincón de Parangueo (RP), Mexico. A multi-scale approach was followed using geological fieldwork, coring of the sediments, ground penetrating radar survey, physico-chemical characterization including X-ray diffraction and scanning electron microscope, and high-throughput DNA sequencing methods. The mobile mud is an organic-rich silty clay, with high values of alkalinity, volumetric water content and conductivity. Mud mobility has been attributed to overpressure caused by disequilibrium compaction of sediments related to active subsidence and pore overpressure produced by an input of groundwater and gas content in the sediments and resulted in a diverse set of structures related to mud tectonics such as injection domes and fluid seeps through fractures. Extraction and sequencing of sedimentary environmental DNA in the mud layer were performed for Bacteria and Archaea. Despite the small number of samples obtained, the microbial fingerprint from the sedimentary environmental DNA at subsurface shares similarities with the microbial communities identified on the crater surface. Additionally, we identify the DNA of specific methanogenic microorganisms in the mud, such as Bathyarchaeia, Methanomassiliicoccales, and Methanobacteriales, and we speculate on their probable role in gas production and pore overpressure in the mud layer. The underground mud at Rincón de Parangueo represents a geologically dynamic environment with conditions that are favorable for the thriving of microbial communities.","PeriodicalId":49601,"journal":{"name":"Revista Mexicana De Ciencias Geologicas","volume":null,"pages":null},"PeriodicalIF":0.8,"publicationDate":"2021-11-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47035160","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Sewage sludge from Taxco de Alarcón wastewater treatment plant as substrate to cultivate Panicum maximum","authors":"Erik Yoel Carreto-Morales, J. A. López-Díaz, Mariana Martínez-Castrejón, O. Talavera-Mendoza, R. C. Almazán-Núñez, G. Hernández-Flores","doi":"10.22201/cgeo.20072902e.2021.3.1617","DOIUrl":"https://doi.org/10.22201/cgeo.20072902e.2021.3.1617","url":null,"abstract":"The management and disposal of the sewage sludge (SS) generated by a wastewater treatment plant (WWTP) as part of the municipal wastewater (MWW) treatment process is one of the main socio-environmental issues faced by this type of system. Taxco de Alarcón, Guerrero, in southern Mexico has had a WWTP operating since 2016, and the SS disposal is a task that must be addressed by the WWTP. Thus, the aim of this work was to evaluate the growth capacity of Panicum maximum, also known as mombaza grass (MG), by using SS generated within the \"Taxco de Alarcón wastewater treatment plant\" as substrate. To do so, 4 g of MG seeds were scattered over 5 kg (dry basis) of SS. As a control, a commercial compost soil was used, hereafter called pattern soil (PS). The experiment was carried out in triplicates for three months and drinking water (water used for human consumption) was used for crop irrigation. Each month a MG harvest was carried out. The response variables analyzed for MG were germination time (one month after plant emergence), height (HMG), growth rate GrMG, and yield (YMG), whereas in the SS and PS the content of organic matter was analyzed. Furthermore, the chemical composition was analyzed using scanning electron microscopy and X-ray energy dispersion spectroscopy (SEM-EDS) on the MG, SS, and PS. The results showed that MG germinated faster on PS (5 days) than germination on SS (7 days). However, the MG grown on SS reached a considerably higher height (45 cm) compared to the height reached on PS (17 cm). Furthermore, the maximum GrMG over SS was also higher than the maximum GrMG observed on the PS, 3.64 and 1.40 cm∙day-1, respectively. In terms of YMG, it was observed that on SS it reached an average monthly YMG of 416 g∙m-2, whereas in PS it reached a YMG of 72 g∙m-2. The chemical analysis detected P, K, Ca, Mg, and S, considered macronutrients in both substrates. Besides, some micronutrients identified in SS were Cu, Fe, Mn, and Zn, whereas in PS it was also possible to detect micronutrients except Mn and Zn. All the macronutrients detected in the substrates were observed in the harvested MG. However, in the MG harvested in PS, Mn and Zn were not detected. Hence, a feasible disposal strategy for the SS generated by the Taxco de Alarcón WWTP is as a substrate for grass forage MG by its high organic matter content, the significant presence of macro and micronutrients, and the performance shown by MG cultivated in SS. Furthermore, the SS characteristics provide added value and can be considered as organic amendments of agricultural soils.","PeriodicalId":49601,"journal":{"name":"Revista Mexicana De Ciencias Geologicas","volume":null,"pages":null},"PeriodicalIF":0.8,"publicationDate":"2021-11-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44277201","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Geology and geochemistry of jasperoids from the ‘Montaña de Manganeso’ district, San Luis Potosí, north-central Mexico","authors":"Joseph Madondo, C. Canet, Fernando Núñez-Useche, E. González-Partida","doi":"10.22201/cgeo.20072902e.2021.3.1651","DOIUrl":"https://doi.org/10.22201/cgeo.20072902e.2021.3.1651","url":null,"abstract":"Large outcrops of jasperoids occur in the ‘Montaña de Manganeso’ mining district in north-central Mexico. They range from massive manganiferous jasperoids to highly brecciated, hematitic jasperoid. The jasperoids of ‘Montaña de Manganeso’ occur mainly as replacements of limestone, sandstone and shale, commonly nearby high-angle fault systems. The mineralogy of the jasperoids consist of quartz and its polymorphs (chalcedony, tridymite and cristobalite), Fe-Mn oxyhydroxides, calcite and minor barite. Many outcrops show evidence of several periods of brecciation and silicification. The geochemical signature of the jasperoids suggests that silicification was product of hydrothermal activity. The jasperoids display enrichment in elements of hydrothermal provenance such as Ba, Sr, As, Cr, Mo, Sb, Ni, Zn and Cu, whereas are strongly depleted in the elements indicative of clastic sources such as Ti, K, Th and Zr. Element ratios such as (Fe+Mn)/Ti, Al/(Al+Fe+Mn), Fe/Mn and U /Th, along with the Al-Fe-Mn and Fe-Mn-(Ni+Co+Cu)×10 ternary diagrams confirm a hydrothermal origin. Low ∑REE, an enrichment of LREE over HREE, negative Ce anomalies and positive Y anomalies (YPASS/HoPAAS) also support the hydrothermal processes. The geological evidence, in the form of a feeder zone and extensive hydrothermal alteration, show that the silica forming the rocks originated from ascending hot fluids.","PeriodicalId":49601,"journal":{"name":"Revista Mexicana De Ciencias Geologicas","volume":null,"pages":null},"PeriodicalIF":0.8,"publicationDate":"2021-11-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43896402","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Deformación frágil en rocas del Mioceno de la región Morelia-Cuitzeo, Michoacán: implicaciones en el sistema geotérmico local","authors":"Alberto Vásquez-Serrano, Elizabeth Rangel-Granados, Víctor Hugo Garduño-Monroy, Gerardo Bermejo Santoyo, Adrián Jiménez-Haro","doi":"10.22201/cgeo.20072902e.2021.3.1669","DOIUrl":"https://doi.org/10.22201/cgeo.20072902e.2021.3.1669","url":null,"abstract":"La deformación frágil se relaciona con la presencia de fallas y fracturas que afectan a la corteza superior de la Tierra. La distribución que tiene la deformación frágil y el arreglo que presentan las fallas y fracturas son variables poco conocidas, a pesar de que tienen una gran influencia en la generación de permeabilidad y son importantes para entender fenómenos como la deformación localizada. En este trabajo se explora la distribución de la deformación frágil y el arreglo de las fracturas que afectan a rocas andesíticas del Mioceno en el área de Morelia-Cuitzeo mediante un análisis cuantitativo de la deformación a escala mesoscópica. Las rocas miocénicas del área de estudio están afectadas por dos familias de fracturas (F1 y F2) relacionadas con dos eventos de deformación frágil (D1 y D2) ocurridos entre el Mioceno y el Holoceno. Las fracturas F1 tienen un rumbo preferencial NNW-SSE y acomodan una extensión ENE-WSW de ~2.5 %. Por otro lado, las fracturas F2 cortan a las fracturas F1, tienen un rumbo ENE-WSW y se relacionan con una extensión ~N-S de 6.8 %. Ambas familias de fracturas tienen un arreglo de fracturas agrupadas y una intensidad de fracturas promedio similar de aproximadamente 17 fracturas/metro. Este comportamiento en la intensidad de fracturas, ante una cantidad de deformación por extensión distinta, se atribuye al tipo de roca. La cantidad de extensión asociada a las dos familias de fracturas se distribuye de manera heterogénea en las rocas, lo que contribuye de manera significativa con la porosidad secundaria (porosidad de fracturas). Adicionalmente, la cantidad y el arreglo de las fracturas sugieren que las rocas miocénicas pueden ser la capa permeable del sistema geotérmico de la zona del lago de Cuitzeo.","PeriodicalId":49601,"journal":{"name":"Revista Mexicana De Ciencias Geologicas","volume":null,"pages":null},"PeriodicalIF":0.8,"publicationDate":"2021-11-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41497606","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Silicic magmas in the Michoacán-Guanajuato Volcanic Field: an overview about plumbing systems, crustal storage and genesis processes","authors":"G. Sosa-Ceballos, M. Boijseauneau-López, J. D. Pérez-Orozco, G. Cifuentes-Nava, X. Bolós, M. Perton, David Simón-Velázquez","doi":"10.22201/cgeo.20072902e.2021.3.1668","DOIUrl":"https://doi.org/10.22201/cgeo.20072902e.2021.3.1668","url":null,"abstract":"The origin of silicic rocks in the Michoacán-Guanajuato volcanic field (MGVF) has been understudied since the volcanic field attracted the attention of researchers. Using geochemical, petrological and structural data from the literature, here we propose a model for the origin of silicic magmas. We found that all volcanic rocks known to date in the MGVF can be divided in 40 % andesite, 33 % basaltic andesite, 15 % basalt, 2 % trachybasalt to trachyandesite, and 10 % dacite-rhyolite. The structural systems that deformed the crust in the MGVF are NNW-SSE-oriented normal faults of the Taxco-San Miguel de Allende fault system, developed during the Oligocene, and the Morelia-Acambay fault system consisting of ENE-SSW to E-W sinistral strike-slip faults developed during the Oligocene-Miocene. In addition to bibliographic data, we present a gravimetric-magnetometric model to investigate the characteristics of the local basement where magmas acquire their final silicic composition, and a seismic tomography model to investigate the deep plumbing system that contribute to form the silicic rocks emplaced on the surface. The only report of assimilation experiments we found in the MGVF literature suggest that plagioclase and pyroxene are more easily digested than quartz by hotter magmas. The digestion of these mineral phases has a direct consequence on the generation of dacites and rhyolites. We propose that regardless of the genesis of andesitic melts, such intermediate magmas arrive to the upper-crust and are forced to evolve within local compression zones where they melt the local granitic basement and form crystal mushes. The compositional variability of silicic rocks in the MGVF is a consequence of the variable mixing between the intermediate magmas and the granitic partial melts.","PeriodicalId":49601,"journal":{"name":"Revista Mexicana De Ciencias Geologicas","volume":null,"pages":null},"PeriodicalIF":0.8,"publicationDate":"2021-11-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49409774","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Las Cabras volcano, Michoacán-Guanajuato Volcanic Field, México: Topographic, climatic, and shallow magmatic controls on scoria cone eruptions","authors":"M. Guilbaud, Athziri Hernández-Jiménez, C. Siebe, S. Salinas","doi":"10.22201/CGEO.20072902E.2021.2.1645","DOIUrl":"https://doi.org/10.22201/CGEO.20072902E.2021.2.1645","url":null,"abstract":"Scoria cones are abundant in most volcanic fields on Earth, such as the Michoacán-Guanajuato Volcanic Field, in the central-western sector of the Trans-Mexican Volcanic Belt. However, there are few in-depth studies on their eruptive style and controlling factors, despite of their diversity in shape and composition which implies a wide range of hazards. Here, we present results of morphologic, stratigraphic, sedimentary, petrographic, and geochemical studies of the prominent Las Cabras scoria cone located west of the Zacapu lacustrine basin in the center of the Michoacán-Guanajuato Volcanic Field. This basaltic andesitic to andesitic volcano formed between 27 and 26 kyrs BP on the steep slopes (>10º) of the lava shield of El Tule volcano. Over time, its dominant eruptive style changed from Strombolian to effusive. Initial explosive activity built a 170-m-high scoria cone and deposited thick tephra fallout on the surrounding sloping terrain. Structures in the deposits indicate that early friable fine-grained tephra underwent significant erosion due to syn-eruptive heavy rain coupled with the sloping nature of the underlying ground. This erosion generated lahars that very likely reached the Zacapu lake based on the pre-eruptive topography. As the explosivity dropped, lava was emitted from the base of the cone first to the S and SE, forming a thick, viscous lobe that filled a pre-existing E-W valley. The flow direction then deviated to the N and NE, to form thinner, less-viscous lobes fed from the vent by an open-channel. The lavas are covered by hummocks made of agglutinates and bombs that indicate that the eruption terminated by catastrophic collapse of the SE sector of the cone, possibly triggered by the intrusion of magma within the cone, which destabilized its downslope segment. The sudden flank failure was potentially associated with a late effusive event and the hummocks may have been carried away by the lava surge. Whole-rock chemical variations and crystal disequilibrium textures point toward a complex magma feeding system, involving mixing and mingling between different magma batches. This study shows that the formation of scoria cones on a terrain with a marked slope (>10°) has profound impacts on the eruption dynamics and related hazards due to its effect on cone stability and ash erosion. It also evidences the erosive effect of syn-eruptive rain on fine-grained tephra, especially when deposited on a slope. Finally, it reveals the complex magmatic processes that may occur in the shallow plumbing system of monogenetic andesitic volcanoes, which could be particularly important in inland areas of continental arcs.","PeriodicalId":49601,"journal":{"name":"Revista Mexicana De Ciencias Geologicas","volume":null,"pages":null},"PeriodicalIF":0.8,"publicationDate":"2021-07-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45028886","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Prefacio","authors":"Isabel Israde-Alcántara, José Luis Macías-Vázquez","doi":"10.22201/cgeo.20072902e.2021.2.1648","DOIUrl":"https://doi.org/10.22201/cgeo.20072902e.2021.2.1648","url":null,"abstract":"En octubre del 2019 la comunidad nacional e internacional de Ciencias de la Tierra fue partícipe del sensible fallecimiento del Dr. Víctor Hugo Garduño Monroy. Víctor Hugo fue conocido no solo por sus contribuciones al conocimiento de la Tectónica de México con fines del entendimiento de la prospección geológica del Petróleo y de la Geotermia en México, sino también por impulsar en nuestro país estudios pioneros de paleosismología. De igual forma trabajó en la interpretación geológico-ambiental de los glifos prehispánicos, lo cual fue su pasión en sus últimos años. Rebasó hipótesis, creando verdades que mediante su visión se hicieron evidentes, marcando así un parteaguas en la investigación de frontera en las distintas aplicaciones de la Geología Estructural. Durante su brillante carrera académica Víctor Hugo cambió la vida de numerosos investigadores y alumnos que fuimos impulsados por su esencia, su simpatía y contagiosa positividad. Su principal laboratorio natural fue su natal Michoacán, donde la comunidad científica admiró su talento para “comunicarse con la Tierra”. En esa su tierra, dedicó muchos años al estudio de los volcanes y apuntaló su célebre frase “La Tierra y los volcanes son de quienes los trabajan”. Por su talento y grandes contribuciones, Víctor Hugo, como lo conocíamos, no será fácilmente olvidado. \u0000En esta sección especial reunimos contribuciones dedicadas a la geología de Michoacán, las cuales rinden homenaje a la vida y obra de nuestro querido Maestro y amigo Víctor Hugo. Los tópicos que cubren estas contribuciones son la geología estructural, vulcanología, el paleomagnetismo, la paleosismologia, riesgos geológicos y planificación territorial. Todos estos trabajos forman parte de una revisión el estado del arte de investigaciones en distintas áreas del conocimiento en Michoacán. En muchas de estas contribuciones Víctor Hugo es coautor, porque estaba trabajando intensamente con sus colaboradores antes de su partida. El primer artículo se refiere a la formación de conos de escoria asociados a una cámara magmática somera y su relación con la topografía y clima dentro del Campo Volcánico de Michoacán-Guanajuato. \u0000Otros artículos serán publicados en los siguientes números de la Revista Mexicana de Ciencias Geológicas.","PeriodicalId":49601,"journal":{"name":"Revista Mexicana De Ciencias Geologicas","volume":null,"pages":null},"PeriodicalIF":0.8,"publicationDate":"2021-07-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48011034","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}