First Finds of Native Gold and Platinum in the Ilmenite Placers of the Ariadnoye Basite–Ultrabasite Intrusion (Primorye)

Doklady Earth Sciences - The basic features of mineralogy and geochemistry of the gold-ilmenite placers, which are spatially and genetically associated with the Ariadnoye intrusion of ultrabasites...     

Event-scale pebble mobility observed by RFID tracking in a pre-Alpine stream: a field laboratory

Understanding coarse sediment transport is crucial for the prediction of sediment migration and the consequent development of fluvial morphologies. In this study, cobble displacements in a pre-Alpine creek have been recorded by means of radio frequency identification (RFID). Pebble monitoring has been systematically performed after each rainfall event with moderate precipitation, in order to exclude the superimposition of sediment displacements induced by triggering factors acting at different times. The analysis of the collected data was carried out through the application of both a principal component analysis and the Buckingham Π theorem. The experimental trends were interpreted considering the ratio of mobile pebbles, the pebbles' displacement and virtual velocity as the dependent variables. These quantities mostly depend on the event peak discharge, with a nonlinear increase of the travelled distance and a growth of up to two orders of magnitude of the virtual velocity (for an approximately 10× increase in peak discharge). An inverse dependency of the virtual velocity on the event duration was also observed. A comparison of the results obtained with those from laboratory investigations of bedload transport mechanics evidenced the differences in parametric trends associated with sediment mobility in the two environments. This contrast brings forward the combination of multiple drivers of sediment mobility, such as local morphology, sediment dimensions and flow unsteadiness, warranting a further in-depth investigation. Representation of results in a dimensionless form is suggested as a good practice to analyse data from case studies characterized by different scales. © 2019 John Wiley & Sons, Ltd.     

Hot Neutral H in the Heliosphere: Elastic H-H, H-p Collisions

Williams et al. (1997) have suggested that a population of hot hydrogen atoms is created in the heliosphere through elastic H-H collisions between energetic `solar' atoms (neutralized solar wind) and interstellar atoms. They used a BGK-like approximation (Bhatnagar et al., 1954) for the Boltzmann collision term and the collision cross sections suggested by Dalgarno (1960). We show that both assumptions result in a significant overestimation of the the H-H collision effect. On the basis of calculated momentum transfer cross-sections for elastic H-H collisions, we argue that elastic H-H and H-p collisions cannot produce hot H atoms in the heliosphere. This revised version was published online in July 2006 with corrections to the Cover Date.     

古新世特提斯北缘前黑海地区盆地的演化与油气远景

本文以ＥＸＸＯＮ公司Ｐ．Ｒ．Ｖａｉｌ等人创立的层序地层学理论为准，对华南泥盆系的层序地层进行了区域上的研究、分析、对比。研究结果表明，从下泥盆统的洛赫科夫阶至上泥盆统的法门阶可识别出２０～２１个Ⅲ级层序。华南泥盆系的岩石地层、生物地层、年代地层的系、统、阶界线均已确定，与层序地层研究结果对比，生物地层界线均比相应的层序地层界线滞后。本文试图以层序地层序列为准，建立一新的地层系统作为相应的生物地层、年代地层的系、统、阶相对应的辅助性地层系统。研究结果表明，在岩石地层、生物地层、年代地层研究程度高的地区，可建立层序地层的系、统、阶界线系统以利于野外作业。华南地区的泥盆系内，除弗拉斯阶与法门阶的阶间界线置于饥饿层（ｓｔａｒｖｅｄｓｅｃｔｉｏｎ）外，其他的阶、统、系界线均位于有关阶（统）顶部层序中的ＨＳＴ的顶面。     

3-D Visual Drill and Blast Design

State-of-the-art software and computer technology provides a vehicle for a new approach to designing and verification of blasting patterns and training of professionals in this area of mining. The objective of this paper is to discuss the use of 3-D computer graphics to improve the understanding of the challenges facing drill and blast operations and describe technologies available for drill and blast planning in surface mining. It is postulated that this approach will have a positive impact on future students, researchers, and mine operators by improving their ability to use techniques, skills, and visually rich tools in solving and documenting mining engineering problems.     

Thermo-tectonic history of the Issyk-Kul basement (Kyrgyz Northern Tien Shan,Central Asia)

Lake Issyk-Kul occupies a large Late Mesozoic–Cenozoic intramontane basin between the mountain ranges of the Northern Kyrgyz Tien Shan. These ranges are often composed of granitoid basement that forms part of a complex mosaic assemblage of microcontinents and volcanic arcs. Several granites from the Terskey, Kungey, Trans-Ili and Zhetyzhol Ranges were dated with the zircon U/Pb method (SHRIMP, LA-ICP-MS) and yield concordant Late Ordovician–Silurian (~ 456–420 Ma) emplacement ages. These constrain the “Caledonian” accretion history of the Northern Kyrgyz Tien Shan in the amalgamated Palaeo-Kazakhstan continent. The ancestral Tien Shan orogen assembled in the Early Permian when final closure of the Turkestan Ocean ensued collision of Palaeo-Kazakhstan and Tarim. A Late Palaeozoic structural basement fabric formed and Middle–Late Permian post-collisional magmatism added to crustal growth of the Tien Shan. Permo‐Triassic cooling (~ 300–220 Ma) of the ancestral Tien Shan was unraveled using ⁴⁰Ar/³⁹Ar K-feldspar and titanite fission-track (FT) thermochronology on the Issyk-Kul granitoids. Apatite thermochronology (FT and U–Th–Sm/He) applied to the broader Issyk-Kul region elucidates the Meso-Cenozoic thermo-tectonic evolution and constrains several tectonic reactivation episodes in the Jurassic, Cretaceous and Cenozoic. Exhumation of the studied units occurred during a protracted period of intracontinental orogenesis, linked to far-field effects of Late Jurassic–Cretaceous accretion of peri-Gondwanan blocks from the Tethyan realm to Eurasian. Following a subsequent period of stability and peneplanation, incipient building of the modern Tien Shan orogen in Northern Kyrgyzstan started in the Oligocene according to our data. Intense basement cooling in distinct reactivated and fault-controlled sections of the Trans-Ili and Terskey Ranges finally pinpoint important Miocene–Pliocene (~ 22–5 Ma) exhumation of the Issyk-Kul basement. Late Cenozoic formation of the Tien Shan is associated with ongoing indentation of India into Eurasia and is a quintessential driving force for the reactivation of the entire Central Asian Orogenic Belt.     

First Data on Noble Metal–Rare Earth Mineralization in Graphite-Bearing Rocks of the Northern Margin of the Khanka Terrain

High-carbon rocks at the northern margin of the Khanka terrane (Primorskii krai) have been found to host new occurrences of noble and rare-earth metals: the largest of them is the Filinskoye deposit. The graphite ores, hosting copper-bearing high-grade gold, silver, monazite, xenotime, sulfides, rutile, barite, and uraninite, demonstrate high ties of carbon with gold and rare earths. The graphite demonstrates δ¹³C from–2.1 to–5.5‰, corresponding to the mantle isotope composition. This suggests that the primary sources of the ore-forming system were deep carbon-bearing fluids.