Petrology and geochemistry of the orbicular granitoid of Sierra de Velasco (NW Argentina) and implications for the origin of orbicular rocks

The Velasco orbicular granitoid is a small (65 × 15 m), irregularly-shaped body that cropsout within the Huaco granite, central Sierra de Velasco, NW Argentina. It consists of ellipsoid-shapedorbicules of 3 to 15 cm length immersed in an aplitic to pegmatitic matrix. The orbicules are formedby a core made up of a K-feldspar megacryst, partially to totally replaced by plagioclase, an inner shellof radial and equant plagioclase crystals, a layer of tangentially oriented biotite laths, and an outer shellof plumose plagioclase crystals, containing diffuse rings of tangentially oriented biotite. The orbiculargranitoid formed in situ in a pocket of evolved and volatile-rich melt segregated from the surroundingpartially crystallized Huaco granite, possibly via a filter pressing mechanism. The segregated meltentrained relatively few K-feldspar megacrysts into the pocket, leaving behind a concentration ofmegacrysts around the pocket. High water concentration caused effective superheating of the meltand destruction of nuclei, with only the large megacrysts surviving as solids. Sudden water-pressureloss and exsolution of the volatile phase, perhaps related to a volcanic eruption or fracturing of thesurrounding granite, caused rapid undercooling of the melt. The orbicules grewin the undercooled meltby heterogeneous nucleation on the megacrysts, which acted as nucleation seeds, and crystallizationof reversely zoned radial plagioclase and sporadic crystallization of tangential biotite rings accordingto fluctuations in its saturation. Orbicular growth gave way to crystallization of the equiaxial interorbicularmatrix in two stages, when sufficient polymerization of the melt was attained. The time scaleof formation of the orbicular granitoid was fast, possibly a matter of a few weeks or months.Fil: Grosse, Pablo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán; ArgentinaFil: Toselli, Alejandro Jose. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto Superior de Correlación Geológica. Universidad Nacional de Tucumán. Facultad de Ciencias Naturales e Instituto Miguel Lillo. Departamento de Geología. Cátedra Geología Estructural. Instituto Superior de Correlación Geológica; ArgentinaFil: Rossi, Juana Norma. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto Superior de Correlación Geológica. Universidad Nacional de Tucumán. Facultad de Ciencias Naturales e Instituto Miguel Lillo. Departamento de Geología. Cátedra Geología Estructural. Instituto Superior de Correlación Geológica; Argentin

La sierra de Velasco en el noroeste argentino. Un ejemplo de magmatismo polifase en el margen de Gondwana.

The Sierra de Velasco is formed of large plutons that are related to each other by intrusive contacts and separated by generally aligned deformation zones. The plutons are composed of calc-alkaline, syn-, late- and post-kinematic granitoids of different ages and intrusion levels. They are grouped in three large batholiths: Aimogasta, Bazán and Patquía. On the northeastern flank, the metamorphic country rock is represented by micaschists, phyllites and quartzites with hornfels (La Cébila Formation), to the north by tonalitic porphyries that in all cases demonstrate a shallow level of the granitoid intrusions. Shape of the plutons, as well as structural characters and grade of deformation indicate that the intrusive sequences began in Ordovician times and culminated in the Carboniferous, with deformation periods during Silurian and Devonian times. © 2007 E. Schweizerbart'sche Verlagsbuchhandlug.La Sierra de Velasco es un extenso afloramiento predominantemente granítico, integrado por plutones calco-alcalinos, sin-, tardío- a post-tectónicos, con edades diferentes y relacionados entre sí tanto a través de fajas de deformación, como por relaciones intrusivas. Los plutones se agrupan en los batolitos: Aimogasta, Bazán, y Patquía. Las rocas metamórficas de caja están representadas por micacitas, filitas y cuarcitas, con corneanas, sobre el flanco nororiental, y pórfiros tonalíticos en el extremo norte de la sierra, que evidencian el emplazamiento somero de los granitos. Las formas de los plutones, así como los caracteres estructurales y grados de deformación, indican que las secuencias graníticas se habrían iniciado en el Ordovícico y culminado en el Carbonífero, con edades de deformación en el Siluro-Devónico.Fil: Toselli, Alejandro Jose. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto Superior de Correlación Geológica. Universidad Nacional de Tucumán. Facultad de Ciencias Naturales e Instituto Miguel Lillo. Departamento de Geología. Cátedra Geología Estructural. Instituto Superior de Correlación Geológica; ArgentinaFil: Miller, Hubert. Universidad de Munich; AlemaniaFil: Aceñolaza, Florencio Gilberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto Superior de Correlación Geológica. Universidad Nacional de Tucumán. Facultad de Ciencias Naturales e Instituto Miguel Lillo. Departamento de Geología. Cátedra Geología Estructural. Instituto Superior de Correlación Geológica; ArgentinaFil: Rossi, Juana Norma. Universidad Nacional de Tucumán; ArgentinaFil: Söllner, Frank. Universidad de Munich; Alemani

COVID-19 and Its Effects on the Management of the Basic Quality Conditions in Universities of Peru, 2022

The purpose of this study was to determine the influences of variables, crisis management, distance education, the organizational image, and student satisfaction on the basic quality conditions in Peruvian universities during the COVID-19 pandemic. A quantitative, nonexperimental explanatory approach with stratified random sampling was used. A questionnaire was applied to 513 students from public and private universities in southern Peru who received distance education during the months of September to November 2022. For the analysis of the results, a structural equation model (SEM). A hierarchical linear regression was carried out to test the hypotheses according to the dimensions studied on the student satisfaction scale. The study findings showed that distance education and student satisfaction had positive impacts on the basic quality conditions, while crisis management and the organizational image had a positive relationship but a smaller effect on the quality of the conditions. We concluded that the applied model allows the causal relationships between variables to be explored and that the results will allow university authorities to generate policies that improve their organizational image and crisis management processes and, at the same time, allow them to better plan their crisis management strategies to achieve better satisfaction within the framework of a sustainable university

Lower Carboniferous post-orogenic granites in central-eastern Sierra de Velasco, Sierras Pampeanas, Argentina: U-Pb monazite geochronology, geochemistry and Sr-Nd isotopes

The central-eastern part of the Sierra de Velasco (Sierras Pampeanas, NW Argentina) is formed by the large Huaco (40 x 30 km) and Sanagasta (25 x 15 km) granite massifs and the small La Chinchilla stock (2 x 2 km). The larger granites intrude into Ordovician metagranitoids and crosscut Devonian (?) mylonitic shear zones, whereas the small stock sharply intrudes into the Huaco granite. The two voluminous granites are biotitic-muscovitic and biotitic porphyritic syeno- to monzogranites. They contain small and rounded tonalitic and quartz-dioritic mafic microgranular enclaves. The small stock is an equigranular, zinnwaldite- and  fluorite-bearing monzogranite. The studied granites are silica-rich (SiO2 > 70%), potassium-rich (K2O > 4%), ferroan, alkali-calcic to slightly calk-alkalic, and moderately to weakly peraluminous (A/CNK = 1.06-1.18 Huaco granite; 1.01-1.09 Sanagasta granite; 1.05-1.06 La Chinchilla stock). They have moderate to strong enrichments in several LIL (Li, Rb, Cs) and HFS (Nb, Ta, Y, Th, U) elements, and low Sr, Ba and Eu contents. U-Pb monazite age determinations indicate Lower Carboniferous crystallization ages: 350-358 Ma for the Huaco granite, 352.7 ± 1.4 Ma for the Sanagasta granite and 344.5 ± 1.4 Ma for the La Chinchilla stock. The larger granites have similar eNd values between ?2.1 and ?4.3, whereas the younger stock has higher eNd of ?0.6 to ?1.4, roughly comparable to the values obtained for the Carboniferous San Blas granite (?1.4 to ?1.7), located in the north of the sierra. The Huaco and Sanagasta granites have a mainly crustal source, but with some participation of a more primitive, possibly mantle-derived, component. The main crustal component can be attributed to Ordovician peraluminous metagranitoids. The La Chinchilla stock derives from a more primitive source, suggesting an increase with time in the participation of the primitive component during magma genesis. The studied granites were generated during a post-orogenic period in a within-plate setting, possibly as a response to the collapse of the previous Famatinian orogen, extension of the crust and mantle upwelling. They are part of the group of Middle Devonian-Lower Carboniferous granites of the Sierras Pampeanas. The distribution and U-Pb ages of these granites suggests a northward arc-parallel migration of this mainly post-orogenic magmatism with time.Fil: Grosse, Pablo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán; ArgentinaFil: Söllner, Frank. Ludwig-Maximilians-Universität; AlemaniaFil: Báez, Miguel Adolfo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto Superior de Correlación Geológica. Universidad Nacional de Tucumán. Facultad de Ciencias Naturales e Instituto Miguel Lillo. Departamento de Geología. Cátedra Geología Estructural. Instituto Superior de Correlación Geológica; ArgentinaFil: Toselli, Alejandro Jose. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto Superior de Correlación Geológica. Universidad Nacional de Tucumán. Facultad de Ciencias Naturales e Instituto Miguel Lillo. Departamento de Geología. Cátedra Geología Estructural. Instituto Superior de Correlación Geológica; ArgentinaFil: Rossi, Juana Norma. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto Superior de Correlación Geológica. Universidad Nacional de Tucumán. Facultad de Ciencias Naturales e Instituto Miguel Lillo. Departamento de Geología. Cátedra Geología Estructural. Instituto Superior de Correlación Geológica; ArgentinaFil: de la Rosa, J. D.. Universidad de Huelva; Españ

Across-arc variation of the Famatinian magmatic arc (NW Argentina) exemplified by I-, S- and transitional I/S-type Early Ordovician granitoids of the Sierra de Velasco

The Early Ordovician granitoids of the Sierra de Velasco reflect the across-arc compositional variation of the Famatinian magmatic arc (NW Argentina) developed along the proto-Andean margin of western Gondwana. This variation is characterized by means of field, petrographical, geochemical and isotopic studies. The Sierra de Velasco contains three main types of Early Ordovician granitoids that are mineralogically and geochemically distinct, but generally conform a continuous high-K, magnesian and calcalkalic magmatic series. I-type granitoids (IG) make up the southern part of the range. They are biotite-hornblende-titanite metaluminous to weakly peraluminous granodiorites and tonalites typical of a coastal I-type belt and were possibly formed by melting of mafic lower crust/lithospheric mantle, with minor assimilation of crustal metasediments. S-type granitoids (SG) crop out in the central and northern portions of the range. They are biotite-muscovite and biotite-cordierite strongly peraluminous syeno- andmonzogranites representative of an inland S-type belt and were possibly formed by large-scaleanatexis of metasedimentary crust and hybridization with more mafic lower crustal melts. Between the IG and SG, in the central parts of the range, transitional I/S-type granitoids (TG) are recognized that consist of biotite, biotite-muscovite and subordinate biotite-titanite-allanite-epidote moderately peraluminous monzogranites, granodiorites and tonalites. The TG show intermediate characteristics and were possibly generated by less common mechanisms of mixing between I-type and S-type magmas and/or their parent mafic lower crustal and metasedimentary melts. The transition from IG to TG to SG towards the continental interior reflects a compositional continuum related to a progressive variation in the degrees of mixing between mafic and metasedimentary end-members.Fil: Grosse, Pablo. Fundación Miguel Lillo; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán; ArgentinaFil: Bellos, Laura Iudith. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto Superior de Correlación Geológica. Universidad Nacional de Tucumán. Facultad de Ciencias Naturales e Instituto Miguel Lillo. Departamento de Geología. Cátedra Geología Estructural. Instituto Superior de Correlación Geológica; ArgentinaFil: de Los Hoyos, Camilo Raul. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto Superior de Correlación Geológica. Universidad Nacional de Tucumán. Facultad de Ciencias Naturales e Instituto Miguel Lillo. Departamento de Geología. Cátedra Geología Estructural. Instituto Superior de Correlación Geológica; ArgentinaFil: Larrovere, Mariano Alexis. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Regional de Investigaciones Científicas y Transferencia Tecnológica de La Rioja. - Universidad Nacional de La Rioja. Centro Regional de Investigaciones Científicas y Transferencia Tecnológica de La Rioja. - Universidad Nacional de Catamarca. Centro Regional de Investigaciones Científicas y Transferencia Tecnológica de La Rioja. - Secretaría de Industria y Minería. Servicio Geológico Minero Argentino. Centro Regional de Investigaciones Científicas y Transferencia Tecnológica de La Rioja. - Provincia de La Rioja. Centro Regional de Investigaciones Científicas y Transferencia Tecnológica de La Rioja; ArgentinaFil: Rossi, Juana Norma. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto Superior de Correlación Geológica. Universidad Nacional de Tucumán. Facultad de Ciencias Naturales e Instituto Miguel Lillo. Departamento de Geología. Cátedra Geología Estructural. Instituto Superior de Correlación Geológica; ArgentinaFil: Toselli, Alejandro Jose. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto Superior de Correlación Geológica. Universidad Nacional de Tucumán. Facultad de Ciencias Naturales e Instituto Miguel Lillo. Departamento de Geología. Cátedra Geología Estructural. Instituto Superior de Correlación Geológica; Argentin

Regional implications of U-Pb zircon ages from rhyolitic pebbles of Suncho Formation conglomerates, northern Sierras Pampeanas (NW Argentina)

Conglomerates are scarce in the Neoproterozoic/Cambrian strata of the South American Central Andean Basin. In NW Argentina, unusual conglomerates within meta-psammites of the Suncho Formation contain rhyolite clasts that yielded 524.9 ± 1.12 Ma and 525.1 ± 1.3 Ma LA-ICP-MS U-Pb zircon ages. These ages coincide with the reported youngest age populations obtained from detrital zircons in the host rocks. The new geochronological data, the regional geology and published data suggest that the source areas of these pebbles were located to the NE and E of the Suncho Formation, which may include some reworked older sedimentary levels of the Puncoviscana Formation. The origin of the Suncho conglomerate is linked to Pre-Tilcaric magmatism which closed the Pampean Cycle, whose ages are in the range 541-517 Ma. The match between the radiometric data and the age provided by the Oldhamia trace fossils with both sedimentary and magmatic events occurring during the Terreneuvian - Series 2 time span ("lower Cambrian") is here emphasized. Considering that the dated rhyolite clasts were derived from magmatic rocks, a Puncoviscana active margin can be proposed as their source, and an active margin setting is proposed for Puncoviscana in this part of the western margin of South America. The knowledge of unusual facies within the Neoproterozoic/Cambrian sequences in the South American Andes provides a better understanding of the geology of little known areas in the western protogondwanan margin.Fil: Toselli, Alejandro Jose. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto Superior de Correlación Geológica. Universidad Nacional de Tucumán. Facultad de Ciencias Naturales e Instituto Miguel Lillo. Departamento de Geología. Cátedra Geología Estructural. Instituto Superior de Correlación Geológica; ArgentinaFil: Aceñolaza, Guillermo Federico. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto Superior de Correlación Geológica. Universidad Nacional de Tucumán. Facultad de Ciencias Naturales e Instituto Miguel Lillo. Departamento de Geología. Cátedra Geología Estructural. Instituto Superior de Correlación Geológica; ArgentinaFil: Stipp Basei, Miguel Angelo. Universidade de Sao Paulo; BrasilFil: Aceñolaza, Guillermo Federico. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto Superior de Correlación Geológica. Universidad Nacional de Tucumán. Facultad de Ciencias Naturales e Instituto Miguel Lillo. Departamento de Geología. Cátedra Geología Estructural. Instituto Superior de Correlación Geológica; ArgentinaFil: Rossi, Juana Norma. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto Superior de Correlación Geológica. Universidad Nacional de Tucumán. Facultad de Ciencias Naturales e Instituto Miguel Lillo. Departamento de Geología. Cátedra Geología Estructural. Instituto Superior de Correlación Geológica; ArgentinaFil: Mantzouka, Dimitra. Universidad Nacional y Kapodistriaca de Atenas; GreciaFil: Tsaparas, Nicolaos. Universidad Nacional y Kapodistriaca de Atenas; GreciaFil: Karakitsios, Vasileios. Universidad Nacional y Kapodistriaca de Atenas; Greci

Global economic burden of unmet surgical need for appendicitis

Background There is a substantial gap in provision of adequate surgical care in many low- and middle-income countries. This study aimed to identify the economic burden of unmet surgical need for the common condition of appendicitis. Methods Data on the incidence of appendicitis from 170 countries and two different approaches were used to estimate numbers of patients who do not receive surgery: as a fixed proportion of the total unmet surgical need per country (approach 1); and based on country income status (approach 2). Indirect costs with current levels of access and local quality, and those if quality were at the standards of high-income countries, were estimated. A human capital approach was applied, focusing on the economic burden resulting from premature death and absenteeism. Results Excess mortality was 4185 per 100 000 cases of appendicitis using approach 1 and 3448 per 100 000 using approach 2. The economic burden of continuing current levels of access and local quality was US $92 492 million using approach 1 and$73 141 million using approach 2. The economic burden of not providing surgical care to the standards of high-income countries was $95 004 million using approach 1 and$75 666 million using approach 2. The largest share of these costs resulted from premature death (97.7 per cent) and lack of access (97.0 per cent) in contrast to lack of quality. Conclusion For a comparatively non-complex emergency condition such as appendicitis, increasing access to care should be prioritized. Although improving quality of care should not be neglected, increasing provision of care at current standards could reduce societal costs substantially

Global economic burden of unmet surgical need for appendicitis

Background There is a substantial gap in provision of adequate surgical care in many low- and middle-income countries. This study aimed to identify the economic burden of unmet surgical need for the common condition of appendicitis. Methods Data on the incidence of appendicitis from 170 countries and two different approaches were used to estimate numbers of patients who do not receive surgery: as a fixed proportion of the total unmet surgical need per country (approach 1); and based on country income status (approach 2). Indirect costs with current levels of access and local quality, and those if quality were at the standards of high-income countries, were estimated. A human capital approach was applied, focusing on the economic burden resulting from premature death and absenteeism. Results Excess mortality was 4185 per 100 000 cases of appendicitis using approach 1 and 3448 per 100 000 using approach 2. The economic burden of continuing current levels of access and local quality was US $92 492 million using approach 1 and$73 141 million using approach 2. The economic burden of not providing surgical care to the standards of high-income countries was $95 004 million using approach 1 and$75 666 million using approach 2. The largest share of these costs resulted from premature death (97.7 per cent) and lack of access (97.0 per cent) in contrast to lack of quality. Conclusion For a comparatively non-complex emergency condition such as appendicitis, increasing access to care should be prioritized. Although improving quality of care should not be neglected, increasing provision of care at current standards could reduce societal costs substantially