Metallogenesis and Geodynamic Setting of the Early Paleozoic Orogenic Gold Deposits in the North Altyn

The North Altyn has underwent a complex tectonic history in the Early Paleozoic and formed a number of orogenic gold deposits controlled by ductile to brittle shear zones adjacent to the southern side of the Northern Altyn Tagh fault e.g. the Dapinggou, Beiketan and Xiangyun. The Dapinggou gold deposit, a typical orogenic gold deposit in North Altyn, is predominantly hosted in the Precambrian carbonate and Cambrian volcano- sedimentary rocks which were strongly deformed and were subjected to low-grade metamorphism. The ore bodies occurred in K-feldspar quartz veins and hydrothermally altered mylonite within the ductile shear belt. Hydrothermal alteration including silicification, pyritization.

In-situ Monitoring the Setting Behavior of Foamed Concrete Using Ultrasonic Pulse Velocity Method

The applicability of ultrasonic pulse velocity （UPV） method to in-situ monitor setting and hardening process of foamed concrete （FC） was systematically investigated. The UPVs of various FC pastes were automatically and continuously measured by a specially designed ultrasonic monitoring apparatus （UMA）. Ultrasonic tests were performed on FC mixtures with different density （300, 500, 800 and 1 000 kg/m3）, and different fly ash contents （0%, 20%, 40% and 60%）. The influence of curing temperatures （20, 40, 60 and 80~C） was also studied. The experimental results show that three characteristic stages can be clearly identified during the setting process of an arbitrary FC paste： dormant stage, acceleration stage, and deceleration stage. Wet density, fly ash content, and curing temperature have great impact on setting behavior. A stepwise increase of the wet density results in shorter dormant stage and larger final UPV. Hydration reaction rate is obviously promoted with an increase in curing temperature. However, the addition fly ash retards the microstn,lcture formation. To aid in comparing with the ultrasonic results, the consistence spread test and Vicat needle test （VNT） were also conducted. A correlation between ultrasonic and VNT results was also established to evaluate the initial and final setting time of the FC mixtures. Finally, certain ranges of UPV with reasonable widths were suggested for the initial and final setting time, respectively.

Coal and gas outburst prevention using new high water content cement slurry for injection into the coal seam

As coal and gas outburst is one of the most serious mine disasters, it is very important to at least control it if not prevent it from occurring. Injecting cement slurry or grouting into the coal seam can strengthen the seam, increase its rigidity coefficient(f), and reduce the volumetric expansion due to gas energy release.This paper reports the results of laboratory experiments on cement-based high water content slurry having different water-cement ratios(W/C) to be used for coal injection. The results show that as the W/C increases, the mobility of the slurry and its setting time increase. The compressive strength and rupture strength, however, are reduced. Furthermore, high W/C grout shows early strength after 7 days, which can be 80% of its 14-day compressive strength. To achieve rapid setting and early strength, the addition of Na_2SiO_3has proven to give the best result, when the concentration of the additive is 3%. The initial and final setting times are 13 and 21 min shorter than samples without Na_2SiO_3, while the compressive strength is more than double. As a retarder, the initial setting time can be extended to 83 min when tartaric acid of 0.4% concentration is added. Through the orthogonal experiment, the optimum recipe of the new high water content slurry has been determined to be: W/C = 2, tartaric acid = 0.2%, Na_2SiO_3= 3%, and12% bentonite. Reinforcement by injection simulation experiments show that the grouting radius of the new slurry mix is 250 mm when the applied grouting pressure is 60 k Pa, 7-day rupture strength and compressive strength are 5.2 and 6.4 MPa, respectively, and are 37% and 88% higher than ordinary cement grout. It can be concluded that the newly developed slurry mix is more effective than the ordinary mix for reinforcing coal and controlling gas outburst.

Are Mikvehs Responsible for GBS Carriers among Orthodox Jewish Women?—A Prospective Observational Study

Background: Maternal colonization with group B streptococcus (GBS) is an important risk factor for neonatal sepsis. A “mikveh” is a pool of water for ritual immersion by Jewish women. It had been reported to be a risk factor for GBS colonization. Objective: To determine whether there is an association between ritual immersion in the mikveh pools and GBS carriership. Methods: Water samples and bacterial swabs were taken from eight mikveh pools centers at two separate occasions and tested for GBS growth. For determination of the total number of live, aerobic bacteria, each sample was grown on strep selective agar for 48 hours at 37°C and CO2 5%. Results: All the samples were tested. No trace of GBS was found in any of the samples. Conclusions: The findings of this study refute earlier findings and suggest that there is no association between ritual immersion in mikvehs and GBS carriership.

Geochronology, Geochemistry and Tectonic Significance of the Early Carboniferous Gabbro and Diorite Plutons in West Ujimqin, Inner Mongolia

Early Carboniferous gabbros and diorites are distributed in West Ujimqin, Inner Mongolia. The LA-ICP-MS zircon U-Pb ages of the gabbro and diorite samples are 321± 2 Ma（MSWD=0.65） and 319.4± 1.5 Ma（MSWD=0.42）, respectively. In addition, new geochemistry data from three gabbro and three diorite samples are presented. All six samples show high Al_2O_3 contents but low-TiO_2 contents, belonging to tholeiitic and calc-alkali basalt series. All of the samples have similar chondrite normalized REE patterns characterized by moderate depletion in LREE similar to normal middle oceanic ridge basalt（MORB）. The MORB and PM-normalized trace element patterns show the enrichment in large ion lithophile elements（LILE, e.g., Rb, Ba and Sr）, depletion in high field strength elements（HFSE） and distinctly negative Nb and Ta anomalies similar to volcanic arc basalt. Furthermore, as shown in the correlation plots of La/Ba vs. La/Nb, Ba/La vs. Ce/Pb, Th/La vs. Ce/Pb, Nb/La vs. Ba/Rb, and Nb/Y vs. La/Yb, the magma source has underwent contamination and metasomatism from the subduction fluid. According to the Zr/Nb, La/Nb, and La/Ta ratios and the Nb/Y vs. Zr/Y and Sm/Yb vs. La/Sm diagrams, the magma was derived from shallow depleted lithospheric mantle and formed by moderate（5%~20%） partial melting of spinel lherzolites. Tectonic setting discrimination diagrams reveal that the gabbros and diorites display both characteristics of MORB and volcanic arc basalt, which is consistent with their geochemical characteristics. On the basis of the geochemical features of these samples, combined with regional geological data and many previous researches in the study area, the Early Carboniferous gabbros and diorites of West Ujimqin are suggested to be formed in an intensely extensional rift setting, and a limited immature ocean basin probably formed after subsequent development.