Petrogenesis and geodynamic implications of Oligocene A-type granite in the Guadalcazar area, San Luis Potosi, central Mexico

The Guadalcazar is located in the Mesa Central (MC) province, which is mainly composed of granitic rocks and is known for its metallogenetic. The granitic rocks contain complex Sn-Hg-Ag-F mineralization and were emplaced during Eocene to Oligocene. However, the source, origin, and evolution of magma and the tectonic setting of this magmatic area have never been explained. In this study, we have conducted petrology, whole-rock geochemistry, and U–Pb zircon geochronology on granitic rocks from the Guadalcazar to constrain the petrogenesis and tectonic environment. LA-ICP-SF-MS zircon U–Pb dating shows that the Guadalcazar granite was emplaced ca. 31 Ma. These rocks are characterized by high (SiO2) contents (64–75 wt%), low CaO (0.28–1.78 wt%), with relatively high (FeOt)adj/(FeOt + MgO) values ranging from 0.90 to 0.98. The geochemical diagrams of SiO2 vs [(FeOt)/(FeOt + MgO)] and SiO2 vs [(Na2O + K2O) − CaO] show the ferroan and mostly alkali-calcic nature of these rocks. The granite shows an A2-type affinity and is strongly peraluminous, with ASI (molar Al2O3/[CaO + Na2O + K2O]) values of 1.13 to 2.60. These granitic rocks are characterized by enrichments in rare earth elements (REE) and high field strength elements (HFSE), and depletion in Ba, Nb, Sr, Ti, and Eu. These features suggest that these A-type granites were derived from the metasedimentary rocks and evolved through extensive fractional crystallization. The multidimensional discrimination diagrams showed a continental rift or within-plate setting. By combining previous and new data, we proposed a new magmatic evolution model that supports an extension during ca. 34–28 Ma in the Guadalcazar, central Mexico

Geochemistry and Sm–Nd isotope systematics of mafic-ultramafic rocks from the Babina and Mauranipur greenstone belts, Bundelkhand Craton, India: Implications for tectonic setting and Paleoarchean mantle evolution

The Paleoarchean geodynamical evolution of the Bundelkhand Craton is discussed based on the geochemistry (major, trace and rare earth elements) and Sm–Nd isotope systematic of mafic-ultramafic rocks from volcano-sedimentary succession of the Babina and Mauranipur greenstone belts. The petrography and mineral assemblages of these mafic-ultramafic rocks imply that they were gone through greenschist to amphibolite facies metamorphism. Geochemical analyses indicate that mafic rocks from the Babina are characterized by SiO 2 = 43.9–51.2 wt%, MgO = 5.4–11.0 wt%, TiO 2 = 0.3–1.14 wt% and Mg# = 44–77, whereas the Mauranipur are characterized by higher silica (51.8–55.6 wt%), MgO = 6.9–9.5 wt% and Mg# = 59–70. The ultramafic rocks from the Babina and Mauranipur contain SiO 2 = 46.9–50.3 wt%, MgO = 20.2–21.1 wt%, TiO 2 = 0.33–0.46 wt% and Mg# = 77–82. Six samples of mafic-ultramafic rocks from the Babina greenstone belt yield 147 Sm– 143 Nd whole rock isochron age of ca. 3.4 Ga. Sm–Nd isotopic studies of mafic rocks from the Babina and Mauranipur reveal that they were derived from a depleted mantle source. Bivariate diagrams such as Cr vs. Ni and V suggest that these magmas might have evolved through fractionation of clinopyroxene and olivine. The mafic rocks from the Babina displayed almost a flat REE and HFSE profile [(La/Yb) PM = 0.87–1.40] with negative Nb (Nb/Nb* = 0.13–0.77) and positive Pb anomalies that could be attributed to metasomatic agents derived from subducting crustal rocks. The Mauranipur mafic rocks show slightly enriched REE [(La/Yb) PM = 1.1–1.7; (La/Sm) PM = 1.1–2.0] with negative Nb anomalies (Nb/Nb* = 0.13–0.77), which are most likely the effects of crustal contamination. The ultramafic rocks from both areas and ultramafic cumulate rock from the Mauranipur display a progressive enrichment from Th, La to Yb, with negative Nb anomalies (Nb/Nb* = 0.40–0.73) with lack of Zr anomalies (Zr/Zr* = 0.10–0.30) that could be attributed to their derivation from shallower mantle. These data collectively suggest that the mafic-ultramafic rocks have been interpreted to be derived from oceanic crust in a subduction-related setting with depleted mantle composition.Fil: Singh, Pradip K.. Instituto Potosino de Investigación Científica y Tecnológica; MéxicoFil: Verma, Sanjeet K.. Instituto Potosino de Investigación Científica y Tecnológica; MéxicoFil: Moreno Moreno, Juan Antonio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Centro de Investigaciones en Ciencias de la Tierra. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Centro de Investigaciones en Ciencias de la Tierra; ArgentinaFil: Singh, Vinod K.. Bundelkhand University; IndiaFil: Malviya, Vivek P.. Yokohama National University. Graduate School of Environmental and Information Sciences; JapónFil: Oliveira, Elson P.. Universidade Estadual de Campinas; BrasilFil: Mishra, Sumit. Bundelkhand University; IndiaFil: Arima, Makoto. Yokohama National University. Graduate School of Environmental and Information Sciences; Japó

Impact of COVID-19 on heart failure hospitalization and outcome in India – A cardiological society of India study (CSI–HF in COVID 19 times study – “The COVID C–HF study”)

Objectives: The presentation and outcomes of acute decompensated heart failure (ADHF) during COVID times (June 2020 to Dec 2020) were compared with the historical control during the same period in 2019. Methods: Data of 4806 consecutive patients of acute HF admitted in 22 centres in the country were collected during this period. The admission patterns, aetiology, outcomes, prescription of guideline-directed medical therapy (GDMT) and interventions were analysed in this retrospective study. Results: Admissions for acute heart failure during the pandemic period in 2020 decreased by 20% compared to the corresponding six-month period in 2019, with numbers dropping from 2675 to 2131. However, no difference in the epidemiology was seen. The mean age of presentation in 2019 was 61.75 (±13.7) years, and 59.97 (±14.6) years in 2020. There was a significant decrease in the mean age of presentation (p = 0.001). Also. the proportion of male patients decreased significantly from 68.67% to 65.84% (p = 0.037). The in-hospital mortality for acute heart failure did not differ significantly between 2019 and 2020 (4.19% and 4.,97%) respectively (p = 0.19). The proportion of patients with HFrEF did not change in 2020 compared to 2019 (76.82% vs 75.74%, respectively). The average duration of hospital stay was 6.5 days. Conclusion: The outcomes of ADHF patients admitted during the Covid pandemic did not differ significantly. The length of hospital stay remained the same. The study highlighted the sub-optimal use of GDMT, though slightly improving over the last few years