Dynamics of the January 2013–June 2014 explosive-effusive episode in the eruption of Volcán de Colima,México: insights from seismic and video monitoring     

Vyacheslav M. Zobin  Raúl Arámbula  Mauricio Bretón  Gabriel Reyes  Imelda Plascencia  Carlos Navarro  Armando Téllez  Arnoldo Campos  Miguel González  Zoraida León  Alejandro Martínez  Carlos Ramírez 《Bulletin of Volcanology》2015,77(4):1-13

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Calc-alkaline rear-arc magmatism in the Fuegian Andes: Implications for the mid-cretaceous tectonomagmatic evolution of southernmost South America     

Mauricio González Guillot  Mónica Escayola  Rogelio Acevedo 《Journal of South American Earth Sciences》2011,31(1):1-16

The magmatic arc of the Fuegian Andes is composed mostly of Upper Mesozoic to Cenozoic calc-alkaline plutons and subordinated lavas. To the rear arc, however, isolated mid-Cretaceous monzonitic plutons and small calc-alkaline dykes and sills crop out. This calc-alkaline unit (the Ushuaia Peninsula Andesites, UPA) includes hornblende-rich, porphyritic quartz meladiorites, granodiorites, andesites, dacites and lamprophyres. Radiometric dating and cross-cutting relationships indicate that UPA is younger than the monzonitic suite. The geochemistry of UPA is medium to high K, with high LILE (Ba 500–2000 ppm, Sr 800–1400 ppm), HFSE (Th 7–23 ppm, Nb 7–13 ppm, Ta 0.5–1.1 ppm) and LREE (La 16–51 ppm) contents, along with relatively low HREE (Yb 1.7–1.3 ppm) and Y (9–19 ppm). The similar mineralogy and geochemistry of all UPA rocks suggest they evolved from a common parental magma, by low pressure crystal fractionation, without significant crustal assimilation. A pure Rayleigh fractionation model indicates that 60–65% of crystal fractionation of 60% hornblende + 34% plagioclase + 4% clinopyroxene + 1% Fe-Ti oxide, apatite and sphene (a paragenesis similar of UPA mafic rocks) can explain evolution from lamprophyres to dacites. The UPA has higher LILE, HFSE and LREE, and lower HREE and Y than the calc-alkaline plutons and lavas of the volcanic front. The HREE and Y are lower than in the potassic plutons as well. High concentrations of Th, Nb, Ta, Zr, Hf, LREE and Ce/Pb, and low U/Th, Ba/Th ratios in UPA, even in the least differentiated samples, suggest contributions from subducted sediments to the mantle source. On the other hand, relatively low HREE and Y, high LREE/HREE (La/Yb 11–38) ratios and Nb-Ta contents can be interpreted as mantle metasomatism by partial melts of either subducted garnetiferous oceanic sediment or basalt as well. Additionally, high LILE content in UPA, similar to the potassic plutons, suggests also a mantle wedge previously metasomatized by potassic parental magmas in their route to crustal levels. Therefore, UPA represents a unique suite in the Fuegian arc generated in a multiple hybridized source. UPA generation is related to a transition from normal to flat subduction which additionally caused the widening and landward migration of the magmatic arc, as well as crustal deformation. Rear-arc magmatism endured ca. 22 m.y.; afterwards, calc-alkaline magmatism remained at the volcanic front.  相似文献   

Ichthyoplankton spatial distribution and its relation with water column stratification in fjords of southern Chile (46°48′–50°09′S) in austral spring 1996 and 2008     

Claudia A. Bustos  Mauricio F. Landaeta  Fernando Balbontín 《Continental Shelf Research》2011,31(3-4):293-303

The occidental shore of the southern tip of South America is one of the largest estuarine ecosystems around the world. Although demersal finfish fisheries are currently in full exploitation in the area, the fjords south of 47°S have been poorly investigated. Two bio-oceanographic cruises carried out in austral spring 1996 and 2008 between 47°S and 50°09′S were utilized to investigate the spatial distribution of fish eggs and larvae. Small differences in the environmental conditions were identified in the top 200 m of the water column between years (5.3–10.5 °C and 0.7–33.9 units of salinity in October 1996; 6.3–11.5 °C and 1.2–34.2 units of salinity in November 2008). The low salinity surface layer generated a highly stable water column within the fjords (Brunt–Väisälä frequency, N>0.1 rad/s; wave period <60 s), whereas a well-mixed water column occurred in the gulfs and open channels. For both years, the ichthyoplankton analysis showed that early life stages of lightfish Maurolicus parvipinnis were dominant (>75% total eggs and >70% total larvae) and they were collected throughout the area, irrespective of the water column stratification. However, other components of the ichthyoplankton such as Falkland sprat Sprattus fuegensis, rockfish Sebastes oculatus, and hoki Macruronus magellanicus were more abundant and found in a wider range of larval sizes in less stable waters (N<0.1 rad/s). Oceanic taxa such as myctophids (Lampanyctodes hectoris) and gonostomatids (Cyclothone sp.) were collected exclusively in open waters. The October 1996 observation of Engraulis ringens eggs in plankton samples corresponded to the southernmost record of early stages of this fish in the Pacific Ocean. We found a significant negative relationship between the number of larval species and N, and a significant positive relationship between the number of larval species and wave period. Therefore, only some marine fish species are capable to utilize fjords systems as spawning and nursery grounds in areas having high amounts of freshwater discharges and very high vertical stratification during austral spring season.  相似文献   

A Markov regime-switching framework to forecast El Niño Southern Oscillation patterns     

Iván Cárdenas-Gallo  Raha Akhavan-Tabatabaei  Mauricio Sánchez-Silva  Emilio Bastidas-Arteaga 《Natural Hazards》2016,81(2):829-843

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Marine Community Ecology and Conservation M.D. Bertness,J.F. Bruno,B.R. Silliman,J.J. Stachowicz (Eds) Sunderland,MA: Sinauer Associates Inc., 2014. 556 pp. ISBN 978‐1‐60535‐228‐2. Hardback: US$109.95.          下载免费PDF全文

Anne Shaffer  Mauricio Carrasquilla‐Henao  Francis Juanes 《Marine Ecology》2016,37(4):927-928

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Snowmelt contribution to the sustainability of the irrigated Mendoza’s Oasis,Argentina: an isotope study     

Hector Massone  Daniel Martinez  Alberto Vich  Mauricio Quiroz Londoño  Darío Trombotto  Sebastián Grondona 《Environmental Earth Sciences》2016,75(6):520

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Groundwater characteristics within loessic deposits: the coastal springs of Los Acantilados,Mar del Plata,Argentina     

Federico Ignacio Isla  Orlando Mauricio Quiroz Londoño  Luis Camilo Cortizo 《Environmental Earth Sciences》2018,77(17):610

The urban growth of the southern neighborhoods of Mar del Plata City provoked significant changes in the groundwater balance of the loessic sequences. These regional loessic levels with a significant portion of volcanic ash layers were reported subject to fluoride and nitrate concentrations. Residential houses pump from sands located 70 m depth and withdraw the sewages to depths less than 5 m. These effects cause significant local and seasonal (summer) increments of the water table outcropping via springs at certain unconformities of the coastal cliffs. A mathematical model was applied to analyze the water level lowering at the productive levels, while there is a decrease in the quality of the upper levels subject to waste discharges. Much of this groundwater flow is concentrated in unconformities between different types of sediments. Human activities have affected the aquifer dynamics increasing the groundwater pumping rates and the return velocity of the sewages. This should be considered in the management strategies of coastal hydric resources.  相似文献   

Built environment and agricultural value at risk from Hurricane Irma flooding in Florida (USA)     

Miller  Alexander J.  Arias  Mauricio E.  Alvarez  Sergio 《Natural Hazards》2021,109(2):1327-1348

Natural Hazards - Flooding is the most costly type of natural disaster, as well as the most frequent. To provide risk-based flood insurance, providers must be able to accurately determine an...  相似文献   

Long-term monitoring of the behavior of a talus-colluvium deposit     

Ehrlich  Mauricio  da Costa  Douglas Pereira  Silva  Rafael Cerqueira 《Landslides》2021,18(6):2225-2245

Landslides - This article describes the behavior of a talus-colluvium deposit up to 70-m thick located in the Serra dos Orgaos, Rio de Janeiro/RJ, Brazil. The monitoring dataset of 13 years...  相似文献   

Evaluation of magmatic processes for the products of the Nevado del Ruiz Volcano, Colombia from geochemical and petrological data     

Nicole Vatin-Prignon  Pierre Goemans  Richard A. Oliver  Eduardo Parra Palacio 《Journal of Volcanology and Geothermal Research》1990,41(1-4)

Trace-element concentrations of the eruptive products from the Nevado del Ruiz volcano indicate that at least for the last 1 Ma, the major controlling factor in the evolution of the magma has been a simple fractional crystallization.The Zr/Hf ratios suggest that the source material is mantle-like in origin and whilst subduction-related contamination of the source material has taken place, there is no evidence that assimilation of continental crust has affected the series.No convincing geochemical evidence for magma mixing was found, and data on banded pumices of Pleistocene, Historic and the 1985 eruptions strongly support a crystal fractionation model to explain the compositional variation of their glasses. Therefore, if mixing has taken place it can only be a mixing of layers within a stratified or partially stratified magma chamber.Modeling of fractional crystallization using a stepwise program has been undertaken and least-squares approximations with small residuals are commensurate with analyzed samples. Crystal fractionation models with plagioclase dominating two-pyroxenes and iron oxides give good fits for all calculations. We conclude that simple crystal fractionation is the process most consistent with major- and trace-element variations in the Ruiz series. This closed-system model requires at least 77% crystal fractionation of a basaltic parent to generate the observed compositions of dacites.  相似文献