Genetic environment of germanium-bearing gold-silver vein ores from the Wolyu mine,Republic of Korea

The Wolyu mine is one of the largest vein-type gold-silver-bearing epithermal systems in the Youngdong district and is the first gold-silver deposit in Korea found to contain significant germanium, in the form of argyrodite (Ag₈GeS₆). Mineralized veins (78.9 ± 1.2 Ma) crosscutting Late Cretaceous hostrock tuff and quartz porphyry (81.5 ± 1.8 Ma) consist of three stages of quartz and carbonates, the first of which contains pyrite, basemetal sulfides and Au-Ag-minerals. Stage I Au-Ag-Ge-mineralized veins show a systematic variation of mineral assemblage with time: (1) quartz + pyrite; (2) quartz + pyrite + sphalerite + electrum + argentite; (3) carbonate + quartz + sphalerite + electrum + argentite; (4) carbonate + native silver + argentite + Ag-sulfosalts + argyrodite + sphalerite. Calculated values of temperature and sulfur activity are: assemblage (1), 360-280°C and 10^–7-10^–10; (2), 280-210°C and 10^–10-10^–14; (3), 210-180°C and 10^–14-10^–16; (4), 180-155°C and 10^–17-10^–18. These data, the frequent association of gold with sulfides, and the abundance of pyrite in alteration zones indicate that decreasing sulfur activity and cooling were important in triggering gold deposition. Hydrogen and oxygen isotope compositions of ore fluids display a systematic variation with increasing time. Within the main Ag-Au-Ge mineralization, D and ¹⁸O values decrease with the transition from quartz to carbonate deposition (from -78 and –2.8% to –90 and –8.7%., respectively), indicating increasing involvement (mixing) of less evolved meteoric water which resulted in progressive cooling and dilution of ore fluids in the shallow ( 370–600 m) Wolyu epithermal system.     

Integration of the nuclease protection assay with sandwich hybridization (NPA-SH) for sensitive detection of Heterocapsa triquetra

Microalgae are photosynthetic microorganisms that function as primary producers in aquatic ecosystems. Some species of microalgae undergo rapid growth and cause harmful blooms in marine ecosystems. Heterocapsa triquetra is one of the most common bloom-forming species in estuarine and coastal waters worldwide. Although this species does not produce toxins, unlike some other Heterocapsa species, the high density of its blooms can cause significant ecological damage. We developed a H. triquetra species-specific nuclease protection assay sandwich hybridization(NPA-SH) probe that targets the large subunit of ribosomal RNA(LSU r RNA). We tested probe specificity and sensitivity with five other dinoflagellates that also cause red tides. Our assay detected H.triquetra at a concentration of 1.5×104 cells/m L, more sensitive than required for a red-tide guidance warning by the Korea Ministry of Oceans and Fisheries in 2015(3.0×104 cells/m L). We also used the NPA-SH assay to monitor H. triquetra in the Tongyeong region of the southern sea area of Korea during 2014. This method could detect H.triquetra cells within 3 h. Our assay is useful for monitoring H. triquetra under field conditions.     

Einstein–Rosen Universe in a Scalar-Tensor Theory of Gravitation

Field equations in the presence of a perfect fluid distribution are obtained in a scalar-tensor theory of gravitation proposed by Saez and Ballester (Phys. Lett. 113, 1985, 467) with the aid of Einstein–Rosen cylindrically symmetric metric. A static vacuum model and a non-static stiff fluid model are presented. The physical and geometrical properties of the stiff fluid model are studied.     

Multiple growth of garnet,sillimanite/kyanite and monazite during amphibolite facies metamorphism: implications for the P–T–t and tectonic evolution of the western Altai Range,Mongolia

Four amphibolite facies pelitic gneisses from the western Mongolian Altai Range exhibit multistage aluminosilicate formation and various chemical‐zoning patterns in garnet. Two of them contain kyanite in the matrix and sillimanite inclusions in garnet, and the others have kyanite inclusions in garnet with sillimanite or kyanite in the matrix. The Ca‐zoning patterns of the garnet are different in each rock type. U–Th–Pb monazite geochronology revealed that all rock units experienced a c. 360 Ma event, and three of them were also affected by a c. 260 Ma event. The variations in the microstructures and garnet‐zoning profiles are caused by the differences in the (i) whole‐rock chemistry, (ii) pressure conditions during garnet growth at c. 360 Ma and (iii) equilibrium temperatures at c. 260 Ma. The garnet with sillimanite inclusions records an increase in pressure at low‐P (~5.2–7.2 kbar) and moderate temperature conditions (~620–660 °C) at c. 360 Ma. The garnet with kyanite inclusions in the other rock types was also formed during an increase in pressure but at higher pressure conditions (~7.0–8.9 kbar at ~600–640 °C). The detrital zircon provenance of all the rock types is similar and is consistent with that from the sedimentary rocks in the Altai Range, suggesting that the provenance of all the rock types was a surrounding accretionary wedge. One possible scenario for the different thermal gradient is Devonian ridge subduction beneath the Altai Range, as proposed by several researchers. The subducting ridge could have supplied heat to the accretionary wedge and elevated the geotherm at c. 360 Ma. The differences in the thermal gradients that resulted in varying prograde P–T paths might be due to variations in the thermal regimes in the upper plate that were generated by the subducting ridge. The c. 260 Ma event is characterized by a relatively high‐T/P gradient (~25 °C km^?1) and may be due to collision‐related granitic activity and re‐equilibrium at middle crustal depths, which caused the variations in the aluminosilicates in the matrix between the rock units.     

Field observations from the Aquila, Italy earthquake of April 6, 2009

On April 6, 2009 an earthquake of magnitude 6.2 (M_w) struck the Abbruzzo region of Italy causing widespread damage to buildings in the city of L??Aquila and surrounding areas. This paper summarizes field observations made by the Earthquake Engineering Field Investigation Team (EEFIT) after the event. The paper presents an overview of seismological and geotechnical aspects of the earthquake as well as a summary of the observed damage to buildings and infrastructure. A brief overview of the earthquake casualties is also reported.     

Underwater Explosion (UWE) Analysis of the ROKS Cheonan Incident

The underwater explosion (UWE) resulting in the sinking of the South Korean warship, ROKS Cheonan occurred on March 26 2010. Raw data was analyzed from several 3-component stations—Baengyeong-do Korea Meteorological Administration (KMA) station (BAR), Ganghwa KMA station (GAHB), Incheon Incorporated Research Institutions for Seismology (IRIS) station (INCN), the short-period station—Deokjeok-do KMA station (DEI), as well as from the seismo-acoustic array Baengyeong-do Korea Institute of Geoscience and Mineral Resources (KIGAM) station (BRDAR). The ROKS Cheonan incident has been investigated by both the Multinational Civilian-Military Joint Investigation Group (Ministry of National Defense, 2010) and Hong (Bull Seism Soc Am 101:1554–1562, 2011). Their respective methods and conclusions are also presented in this study. One of the main differences between their findings and ours is that we deducted that the fundamental bubble frequency was 1.01 Hz with a subsequent oscillation of 1.72 Hz. Also, in contrast to findings by the MCMJIG and Hong, our analysis shows the first reverberation frequency to be 8.5 Hz and the subsequent one to be ≈25 Hz. The TNT-equivalent charge weight (seismic yield) and seismic magnitude were estimated from an observed bubble frequency of 1.01 Hz and the analytical model of a bubble pulse. From the data analyzed, we deducted that the seismic yield would be about 136 kg of TNT, which is equivalent to the individual yield of a large number of land control mines (LCM) which were abandoned in the vicinity of the ROKS Cheonan incident by the Republic of Korea (ROK) Navy in the 1970s (Ministry of National Defense 2010). Also, whereas both the MCMJIG and HONG estimated the local magnitude at 1.5, our findings came to the conclusion of a local magnitude of approximately 2.04 based on the bubble frequency of 1.01 Hz measured on the vertical component of BAR station data considering the empirical relationship between charge weight (TNT yield) and underwater explosion magnitude. Strong high-frequency signals collected at the 3-component BAR station approximately 30 s after P-wave arrivals and infrasound records at BRDAR clearly indicate powerful acoustic phases and N-waves caused by a relatively shallow UWE. T-phases are also observed on seismograms and spectra at 15–17 Hz on the DEI, GAHB, and INCN stations.     

The use of remotely sensed data and ground survey tools to assess damage and monitor early recovery following the 12.5.2008 Wenchuan earthquake in China

The M7.9 Wenchuan earthquake on May 12th, 2008 was the most destructive in China since 1976. The event caused huge damage and loss of life and exposed weaknesses both in the formulation and implementation of the regulations governing building in the affected provinces. Following the earthquake a massive relief and recovery operation was mounted by the Chinese government. The authors took part in field studies in the affected area which took place 5 and 11?months after the event, at which time recovery operations were well-advanced. The aims of the study were to assess the effects caused by the earthquake to the built environment and society, to collect information on the ongoing recovery efforts and future plans, and to demonstrate the use of tools that allow the collection of spatially referenced damage and recovery data. Based on available satellite imagery supplemented by ground observation, geodatabases were constructed containing information on damage and recovery in several parts of the affected area. The paper gives an overview of the recovery process, describes the methods used to construct these geodatabases, and offers some analysis of the data obtained. It is argued that such databases have great potential for the management of post-disaster recovery and for creating a permanent record of the recovery process.     

2007 August 15 magnitude 7.9 earthquake near the coast of Central Peru: analysis and field mission report

A field reconnaissance mission was led to the areas affected by the disaster caused by the Magnitude 7.9 earthquake event of 15/08/2007 near the city of Pisco in Peru. The main objectives of the mission were to collect data and make observations leading to improvements in design methods and techniques for strengthening and retrofit, and to assist the phase of reconstruction. The mission focused on the behaviour of non-engineered structures, in particular those of adobe constructions. The findings of the mission confirmed that most of the damage was observed on adobe houses constructed with traditional non anti-seismic techniques which either collapsed or nearly collapsed, causing 519 deaths, 1,366 injuries and more than 58,000 houses destroyed. The mission also confirmed that buildings constructed according to modern earthquake resistant design standards performed with no evident damage. All the parties contacted during the mission, especially the EC Delegation, showed particular interest in the results of the present mission report, which will be taken into consideration when planning the reconstruction phase, especially of the most distant rural areas, where close collaboration between the Governmental Institutions, International Organizations, Universities and NGO’s, will be needed to assist the population for the adoption of earthquake resistant designs in the reconstruction of the destroyed houses.