Geochemistry and geochronology of the Paleozoic sedimentary rocks in the Shar Khutul area, Central Mongolia

The study area is located in the central part of Tsetserleg terrane in the southwestern margin of the Khangai-Khentey orogenic system. The paper presents new data on geochemistry and geochronology of sedimentary rocks from the Shar Khutul area, where the Tsetserleg terrane consists of Silurian-Devonian oceanic plate stratigraphic unit and Carboniferous shallow water sediment. The Upper Silurian to Middle Devonian Erdenetsogt Formation (S3-D2er), which is an oceanic plate stratigraphic unit, is mainly composed of siliceous siltstone, volcanites, tuffs, quartzite, and cherts. The shallow water sediments are divided into Upper Devonian to Lower Carboniferous Tsetserleg Formation (D3-C1cc) and Lower–Middle Carboniferous Dzargalant Formation (C1-2dz). The Tsetserleg Formation (D3-C1cc) consists of only sedimentary rocks such as bluish-grey sandstones and siltstones, and Lower–Middle Carboniferous Dzargalant Formation (C1-2dz) is principally composed of medium- to coarse-grained, brown-greenish grey sandstones with thin-layers of dark siltstones and gravelites. The SiO2 content of the Shar Khutul area sandstones ranges from 63.85 to 67.95 wt.% and the average content of TiO2 is 0.72 wt.% and Al2O3 content is 14.38 wt.%. The Chemical Index of Alteration (CIA) value ranges from 48.71 to 56.94 and the range of Index of compositional variations (ICV) is from 0.98 to 1.24. Moreover, the samples studied show that most of the sandstones are generally immature and were derived from weakly weathered source rocks. The ratios of Eu/Eu* (0.83), La/Sc (3.81), La/Co (5.30), and Cr/Th (13.81) indicate that the derivation of the Shar Khutul area sandstones from felsic rock sources and confirm the signatures of a felsic igneous provenance and suggest an active continental margin tectonic setting of the source area. The clastic zircons from the medium grained sandstone (Erdenetsogt formation) yield ages between 2.5 Ga and 236 Ma and the detrital zircons exhibit four peak ages at 1.7-2.5 Ga (n = 13), 455-499 Ma (n = 6), 337-382 Ma (n = 13) and 236–250 Ma (n = 5)

Impact of COVID-19 on cardiovascular testing in the United States versus the rest of the world

Objectives: This study sought to quantify and compare the decline in volumes of cardiovascular procedures between the United States and non-US institutions during the early phase of the coronavirus disease-2019 (COVID-19) pandemic. Background: The COVID-19 pandemic has disrupted the care of many non-COVID-19 illnesses. Reductions in diagnostic cardiovascular testing around the world have led to concerns over the implications of reduced testing for cardiovascular disease (CVD) morbidity and mortality. Methods: Data were submitted to the INCAPS-COVID (International Atomic Energy Agency Non-Invasive Cardiology Protocols Study of COVID-19), a multinational registry comprising 909 institutions in 108 countries (including 155 facilities in 40 U.S. states), assessing the impact of the COVID-19 pandemic on volumes of diagnostic cardiovascular procedures. Data were obtained for April 2020 and compared with volumes of baseline procedures from March 2019. We compared laboratory characteristics, practices, and procedure volumes between U.S. and non-U.S. facilities and between U.S. geographic regions and identified factors associated with volume reduction in the United States. Results: Reductions in the volumes of procedures in the United States were similar to those in non-U.S. facilities (68% vs. 63%, respectively; p = 0.237), although U.S. facilities reported greater reductions in invasive coronary angiography (69% vs. 53%, respectively; p < 0.001). Significantly more U.S. facilities reported increased use of telehealth and patient screening measures than non-U.S. facilities, such as temperature checks, symptom screenings, and COVID-19 testing. Reductions in volumes of procedures differed between U.S. regions, with larger declines observed in the Northeast (76%) and Midwest (74%) than in the South (62%) and West (44%). Prevalence of COVID-19, staff redeployments, outpatient centers, and urban centers were associated with greater reductions in volume in U.S. facilities in a multivariable analysis. Conclusions: We observed marked reductions in U.S. cardiovascular testing in the early phase of the pandemic and significant variability between U.S. regions. The association between reductions of volumes and COVID-19 prevalence in the United States highlighted the need for proactive efforts to maintain access to cardiovascular testing in areas most affected by outbreaks of COVID-19 infection

Variation in Electrocution Rate and Demographic Composition of Saker Falcons Electrocuted at Power Lines in Mongolia

We examined variation in the number and demographic composition of electrocuted Saker Falcons (Falco cherrug) in Mongolia. We found 1721 electrocuted Saker Falcons during our surveys of multiple power lines in 2013-2015 and 2018. At a single power line surveyed over a 16-mo period in 2013-2014, the lowest electrocution rates occurred from December to March, with a rise in April coinciding with the return of migrant juveniles from their wintering areas. Electrocution rates rose sharply during juvenile post-fledging dispersal, and then declined in October as migrants departed. Monthly changes in electrocution rate and age profile reflected predicted variation in abundance and age structure of the local Saker Falcon population. We found that 88% of electrocuted Saker Falcons were juveniles, mostly killed during their first calendar year. The sex ratio of electrocuted juveniles fledged in the 2013 cohort (hatch-year birds) was significantly female-biased, in contrast to the equal sex ratio of the 2012 juvenile cohort (second calendar-year birds) killed in the same year (2013). Sex ratio of the 2013 juvenile cohort did not differ significantly from parity at other power lines across Mongolia, indicating that sex ratio of electrocuted juveniles can vary in time and space. The sex of electrocuted adults, predominantly males, and an age profile of breeding Saker Falcons that includes younger females suggests a possible male-biased sex ratio among adult Saker Falcons in Mongolia. Given that large numbers of endangered Saker Falcons are electrocuted annually in Mongolia, our study suggests electrocution may be an important driver of demographic trends that can potentially result in population declines