Ridge subduction and crustal growth in the Central Asian Orogenic Belt: Evidence from Late Carboniferous adakites and high-Mg diorites in the western Junggar region, northern Xinjiang (west China)

The Central Asian Orogenic Belt (CAOB) is a natural laboratory for the study of accretionary tectonics and crustal growth owing to its massive generation of juvenile crust in the Paleozoic. There is a debate, however, on the mechanism of this growth. In the Baogutu area of the western Junggar region, northern Xinjiang (west China), diorite–granodiorite porphyry plutons and dikes are widely associated with Cu–Au mineralization. In this study, we present new results of zircon U–Pb geochronology, major and trace elements, and Sr–Nd–Pb–Hf isotope analyses for two diorite–granodiorite porphyry plutons and two dikes from this area. LA-ICP-MS zircon U–Pb analyses of four plutonic and dike samples yield Late Carboniferous ages of 315–310 Ma. The Baogutu diorite–granodiorite porphyries exhibit low-Fe and calc-alkaline compositions.They are also characterized by high Sr (346–841 ppm) contents, low Y (9.18–16.5 ppm) and Yb (0.95–1.60 ppm) contents, and relatively high Sr/Y (31–67) ratios, which are similar to those of typical adakites. In addition, some samples have relatively high MgO (2.35–8.32 wt.%) and Mg# (48–75), and Cr (22.7–291 ppm) and Ni (32.0–132 ppm) values, which are similar to those of high-Mg andesites. All rock samples exhibit mid-oceanic ridge basalt (MORB)-like Nd–Sr–Pb–Hf isotope features: high εNd(t) (+ 5.8–+8.3) and εHf(t) (+ 13.1–+15.7) values, and relatively low (87Sr/86Sr)i (0.7033 to 0.7054) and (206Pb/204Pb)i (17.842–18.055). The Baogutu adakitic rocks also contain reversely zoned clinopyroxene phenocrysts, which have low MgO cores and relatively high MgO rims. Geochemical modeling indicates that the Baogutu adakitic rocks could have been derived by mixing ~ 95% altered oceanic crust-derived melts with ~ 5% sediment-derived melts.Taking into account the regional geology, I- and A-type granitoids and Cu–Au mineralization, and the presence of Carboniferous ophiolite mélanges in northern Xinjiang, we suggest that the Baogutu adakitic rocks were most probably generated by partial melting of a slab edge close to a subducting spreading ridge in the Late Carboniferous. Ridge subduction and the resultant slab window probably caused strong extension in the overlying lithosphere, extensive melting of subducting oceanic crust, mantle and juvenile lower crust, and interaction between slab-derived melts and the mantle. Thus, events associated with ridge subduction are likely to have played an important role in crustal growth in the CAOB in addition to previously recognized accretion of subduction and arc complexes and post-collisional crustal melting.Research Highlights ►New constraints on ridge subduction in the Central Asian Orogenic Belt (CAOB). ►315-310 Ma adakites and high-Mg diorites occur in the western Junggar region, CAOB. ►Major and trace element, and Sr-Nd-Pb-Hf isotope data indicate slab melting. ►Ridge subduction and the resultant slab window probably caused extensive melting. ►Ridge subduction played an important role in crustal growth in the CAOB

Zoonotic disease risk perceptions and infection control practices of Australian veterinarians: Call for change in work culture

This study was conducted to determine the perceptions of zoonotic disease risk among Australian veterinarians, the infection control practices they use to protect themselves from zoonotic diseases, and the factors influencing their use of these protective practices. A questionnaire was designed and piloted prior to its administration to veterinarians at the annual Australian Veterinary Association Conference in May 2011. The questionnaire comprised 21 closed, semi-closed and open questions. Data from the questionnaire were analyzed using ordinal logistic regression analyses to determine significant factors for veterinarians’ use of personal protective equipment (PPE). A total of 344 veterinarians completed the questionnaire of which 63.7% were women, 63.2% worked in small/companion animal practice, and 79.9% worked in private veterinary practice. Of the respondents, 44.9% reported contracting a zoonosis during their careers with 19.7% reporting a suspected case and 25.2% reporting a confirmed incidence. Around 40–60% of veterinarians perceived exposure to zoonosis likely or very likely in a variety of situations. With reference to current national industry guidelines, the reported use of PPE was less than “adequate” for most scenarios except for performing postmortems, surgery or dental procedures. No PPE was used by 60–70% of veterinarians for treating respiratory and neurological cases and by 40–50% when treating gastrointestinal and dermatological cases. Workplace conditions need improvement as 34.8% of workplaces did not have isolation units for infected animals, 21.1% did not have separate eating areas for staff, and 57.1% did not have complete PPE kits for use. Veterinarians were more likely to use PPE if they had undertaken postgraduate education, perceived that zoonosis exposure from animals and procedures was likely, consciously considered PPE use for every case they dealt with and believed that liability issues and risks encouraged use of PPE. In contrast, those working in private practices, those who tended to ‘just hope for the best’ when trying to avoid zoonotic diseases, and those who were not aware of industry guidelines were less likely to use PPE. The results suggest that veterinarians’ perceptions and workplace policies and culture substantially influence their use of PPE. Efforts should be made to encourage veterinarians and their workplaces to use infection control practices to protect themselves and their staff from zoonotic diseases

Geochronology and geochemistry of Late Paleozoic magmatic rocks in the Lamasu–Dabate area, northwestern Tianshan (west China): Evidence for a tectonic transition from arc to post-collisional setting

Voluminous Late Paleozoic igneous rocks and associated Cu–Au–Mo deposits occur in the northwestern Tianshan district, Xinjiang, west China. However, the tectonic setting and petrogenesis of these rocks remain controversial. This paper reports zircon U–Pb and Hf CUU isotopic data, major and trace elements, and Sr–Nd–Pb isotopic data for the intrusive rocks and minor dacites in the Lamasu–Dabate area of northwestern Tianshan adjacent to the Cu–Au–Mo deposits. LA-ICPMS U–Pb zircon analyses suggest that the Lamasu porphyries were formed at 366 ± 3 Ma and contain 907–738 Ma inherited zircons, the Dabate dacites were formed at 316 ± 4 Ma, and granite porphyries were formed at 289 ± 3 Ma with ~ 319 Ma inherited zircons. The Lamasu porphyries consist of plagioclase granite and granodiorite, and are geochemically similar to adakites, e.g., having high Al2O3 (14.54–19.75 wt.%) and Sr (308–641 ppm) and low Y (7.84–16.9 ppm) contents, with fractionated rare earth element (REE) patterns and slightly positive Sr anomalies.However, they have variable initial ratios of 87Sr/86Sr (0.7072–0.7076) and 206Pb/204Pb (18.139–18.450), and variable εNd(t) (− 5.6 to − 0.8) and positive εHf(t) (+ 1.4 to + 10.6) values. They also have variable Mg# (100 × Mg2+/(Mg2++ Fe2+)) (41–73) and low Th (3.13–8.09) and Th/Ce (0.14–0.28) values. We suggest that the Lamasu adakitic magmas were generated through partial melting of southward subducted Junggar oceanic crust, with subsequent melt-mantle interaction and assimilation of basement rocks. The Dabate dacites show typical arc-like geochemical characteristics (e.g., enrichment of large ion lithophile elements (LILE) and strong negative anomalies of Ta, Nb, P and Ti), with variable εNd(t) (+ 0.1 to + 3.3). They were probably generated by melting of juvenile basaltic lower crust as a result of magma underplating.The Dabate granite porphyries are geochemically similar to A2-type granites, e.g., high SiO2 (75.6–77.6 wt.%) and alkalis (Na2O + K2O = 8.27–8.70 wt.%), low CaO (0.28–0.34 wt.%) and Mg# (2–10), and obvious negative Eu, Ba and Sr anomalies. They have variable values of εNd(t) (− 1.7 to 0) and 206Pb/204Pbi (18.567–18.721) and zircon εHf(t) (+ 0.5 to + 11.1). The Dabate A-type granite porphyries contain Late Carboniferous residual zircon cores, suggesting that their source rock possibly contained Carboniferous arc igneous rocks. Taking into account all available data from Late Paleozoic magmatic rocks and Cu–Mo–Au mineralization in the northern Tianshan district, we suggest that the Dabate–Lamasu area was a continental arc during the Late Devonian–Carboniferous but had entered a post-collisional stage by the Early-Permian (~ 290 Ma)

A Replicating Modified Vaccinia Tiantan Strain Expressing an Avian-Derived Influenza H5N1 Hemagglutinin Induce Broadly Neutralizing Antibodies and Cross-Clade Protective Immunity in Mice

published_or_final_versio

Effects of antenatal depression screening and intervention among Chinese highâ risk pregnant women with medically defined complications: A randomized controlled trial

Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/151825/1/eip12731_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/151825/2/eip12731.pd