scholarly journals Caracterización estructural del sistema de ledges y clavos mineralizados del sector Cachinalito, mina El Guanaco, región de Antofagasta, Chile

2021 ◽  
Vol 48 (1) ◽  
pp. 110
Author(s):  
Sebastián Jovic ◽  
Gerardo Páez ◽  
Matías Galina ◽  
Diego Guido ◽  
Conrado Permuy Vidal ◽  
...  
Keyword(s):  
Structural Control ◽  
General Structure ◽  
Low Grade ◽  
Key Factors ◽  
The North ◽  
Metallogenic Belt ◽  
Epithermal Gold Deposit ◽  
Ascending Pathways ◽  
Exploration Tool ◽  
Western Side

The high sulfidation epithermal gold deposit El Guanaco is located in the Palaeocene-Lower Eocene metallogenic belt in the Antofagasta Region, northern Chile, 215 km SE of Antofagasta city. The deposit is characterized by a system of sub-parallel ledges made of vuggy silica and quartz enargite veins. In the Cachinalito sector, on the north western side of the ore deposit, the ledges system has a discontinuous linear morphology, with a general ENE-OSO orientation, consisting of many ledges segments that change abruptly in orientation, thickness, length and inclination. Grade analysis distribution, detailed mapping at deposit scale, and identification of individual structures (ledges) shows that one of the key factors in deposit genesis is the structural control. The structural analysis allowed visualizing the different segmentations within a general structure, considering the sizes, horizontal and vertical continuity, degree of connection between ledge segments of different orientations, as well as determining the orientations with greater development of mineralized structures. The distribution of the grades allowed to characterize and identify the ore shoots within the ledges, and to interpret the ascending pathways of the mineralizing fluids by dimensioning and separating the high- and low-grade mineralized sectors. This type of analysis and identification represents an important exploration tool and helps exploration and / or production drilling in this type of deposit.

Effect of Temperature on Column Bioleaching of a Refractory Gold Ore

2013 ◽  
Vol 825 ◽  
pp. 352-355 ◽  
Author(s):  
Zeng Ling Wu ◽  
Zhong Sheng Huang ◽  
Ren Man Ruan ◽  
Shui Ping Zhong ◽  
Brenda K.C. Chan
Keyword(s):  
Sulfide Oxidation ◽  
Effect Of Temperature ◽  
Low Grade ◽  
Key Factors ◽  
Gold Extraction ◽  
Gold Ores ◽  
Fraction Distribution ◽  
Higher Temperature ◽  
Liberation Analysis ◽  
Main Factor

Low-grade, finely disseminated refractory sulfide gold ores associated with high arsenic are ubiquitous resources all over the world. Since heap bio-oxidation is an economic and promising biotechnology to recover gold, low grade, high organic carbon and arsenic bearing gold ores from Zhesang Mines in China were chosen for this purpose to study the key factors that would affect biooxidation. Pyrite and arsenopyrite (particle size 0.002-0.22 mm) were the main minerals from Mineral Liberation Analysis (MLA). Column biooxidation and cyanidation of mineral size < 10 mm were evaluated for its potential for gold extraction. Results showed that temperature was the main factor influencing sulfide oxidation. 58-67 % of sulfide was oxidized at 35-45°C after > 240 days of biooxidation with mixed mesophiles, while higher sulfide-S dissolution (77%) was obtained at 60°C. Sulfide-S fraction distribution revealed higher mineral decomposition, finer fractions and eventually higher sulfide oxidation at 60°C. Jarosite and scorodite were found from the residues at 60°C by SEM and EDX, which implies higher temperature accelerated arsenic precipitation. No elemental sulfur was detected during the biooxidation at 35-60°C. After bio-oxidation, column cyanidation was successfully demonstrated recovery of gold from the residues, with gold extraction rate reaching 66%.

Understanding pre- and syn-orogenic tectonic evolution in western Himalaya through age and petrogenesis of Palaeozoic and Cenozoic granites from upper structural levels of Bhagirathi Valley, NW India

2021 ◽  
pp. 1-27
Author(s):  
Aranya Sen ◽  
Koushik Sen ◽  
Amitava Chatterjee ◽  
Shubham Choudhary ◽  
Alosree Dey
Keyword(s):  
Inductively Coupled Plasma ◽  
Age Distribution ◽  
Normal Fault ◽  
Western Himalaya ◽  
Indian Plate ◽  
Low Grade ◽  
Inductively Coupled ◽  
The North ◽  
Plasma Mass Spectrometry ◽  
Structural Levels

Abstract The Himalaya is characterized by the presence of both pre-Himalayan Palaeozoic and syn-Himalayan Cenozoic granitic bodies, which can help unravel the pre- to syn-collisional geodynamics of this orogen. In the Bhagirathi Valley of Western Himalaya, such granites and the Tethyan Himalayan Sequence (THS) hosting them are bound to the south by the top-to-the-N extensional Jhala Normal Fault (JNF) and low-grade metapelite of the THS to its north. The THS is intruded by a set of leucocratic dykes concordant to the JNF. Zircon U–Pb laser ablation multi-collector inductively coupled plasma mass spectrometry (LA-MC-ICP-MS) geochronology of the THS and one leucocratic dyke reveals that the two rocks have a strikingly similar age distribution, with a common and most prominent age peak at ~1000 Ma. To the north of the THS lies Bhaironghati Granite, a Palaeozoic two-mica granite, which shows a crystallization age of 512.28 ± 1.58 Ma. Our geochemical analysis indicates that it is a product of pre-Himalayan Palaeozoic magmatism owing to extensional tectonics in a back-arc or rift setting following the assembly of Gondwana (500–530 Ma). The Cenozoic Gangotri Leucogranite lies to the north of Bhaironghati Granite, and U–Pb dating of zircon from this leucogranite gives a crystallization age of 21.73 ± 0.11 Ma. Our geochemical studies suggest that the Gangotri Leucogranite is a product of muscovite-dehydration melting of the lower crust owing to flexural bending in relation to steepening of the subducted Indian plate. The leucocratic dykes are highly refracted parts of the Gangotri Leucogranite that migrated and emplaced along extensional fault zones related to the JNF and scavenged zircon from the host THS during crystallization.

New data on the fauna and the biogeographic structure of the Hydrozoa, Scyphozoa, Staurozoa and Alcyonacea (Anthozoa) of the Kara Sea

2021 ◽  
Vol 325 (2) ◽  
pp. 143-155
Author(s):  
N.E. Zhuravleva
Keyword(s):  
Cold Water ◽  
Kara Sea ◽  
Novaya Zemlya ◽  
The North ◽  
Anna Trough ◽  
New Material ◽  
Western Side ◽  
Academy Of Sciences ◽  
North Western ◽  
Arctic Fauna

The paper considers the species composition of the fauna of several cnidarian groups of the Kara Sea. The author presents a list of species of the studied groups and indicates the types of habitat for each species. The analysis was based on the literature data, the collections of the Zoological Institute of the Russian Academy of Sciences and material collected in the Kara Sea during the expedition to the R/V Professor Multanovsky in 2019. In total, 87 species of Hydrozoa, 3 species of Scyphozoa, 4 species of Staurozoa, and 5 species of the order Alcyonacea from the class Anthozoa were recorded for the fauna of the Kara Sea, based on the new material obtained by the author and published literature data. The report presents the biogeographic structure of the discussed cnidarian groups. According to the types of biogeographic ranges, the fauna of the above-mentioned cnidarian groups in the Kara Sea mostly consists of representatives of the Boreal-Arctic type of habitat (63%), the Boreal and Amphiboreal biogeographic groups each containing 12% of the total number of described species, and the Panoceanic and Arctic groups together accounting for only 9% and 4% of the fauna of the Kara Sea. Two species new for the Kara Sea, Neoturris pileata (Forsskål, 1775) and Neoturris pileata (Forsskål, 1775), are described. Neoturris pileata is an element of the warm-water Atlantic fauna that penetrated into the Kara Sea with waters of Atlantic genesis. Nausithoe werneri is an element of the cold-water Arctic fauna that penetrated into the Novaya Zemlya Trough of the Kara Sea from the north-western side from the St. Anna Trough, which was open to the Polar Basin.

scholarly journals The concurrence of Atmospheric Rivers and explosive cyclogenesis in the North Atlantic and North Pacific basins

2017 ◽  
Author(s):  
Jorge Eiras-Barca ◽  
Alexandre M. Ramos ◽  
Joaquim G. Pinto ◽  
Ricardo M. Trigo ◽  
Margarida L. R. Liberato ◽  
...  
Keyword(s):  
North Atlantic ◽  
North Pacific ◽  
Reanalysis Data ◽  
Water Vapour Flux ◽  
Atmospheric Rivers ◽  
The North ◽  
Explosive Cyclones ◽  
The North Atlantic ◽  
Characteristic Features ◽  
Western Side

Abstract. The explosive cyclogenesis of extra-tropical cyclones and the occurrence of atmospheric rivers are characteristic features of baroclinic atmospheres, and are both closely related to extreme hydrometeorological events in the mid-latitudes, particularly on coastal areas on the western side of the continents. The potential role of atmospheric rivers in the explosive cyclone deepening has been previously analysed for selected case studies, but a general assessment from the climatological perspective is still missing. Using ERA-Interim reanalysis data for 1979–2011, we analyse the concurrence of atmospheric rivers and explosive cyclogenesis over the North Atlantic and North Pacific Basins for the extended winter months (ONDJFM). Atmospheric rivers are identified for almost 80 % of explosive deepening cyclones. For non-explosive cyclones, atmospheric rivers are found only in roughly 40 % of the cases. The analysis of the time evolution of the high values of water vapour flux associated with the atmospheric river during the cyclone development phase leads us to hypothesize that the identified relationship is the fingerprint of a mechanism that raises the odds of an explosive cyclogenesis occurrence and not merely a statistical relationship. This insight can be helpful for the predictability of high impact weather associated with explosive cyclones and atmospheric rivers.

scholarly journals An analysis of the contrasting fates of locust swarms on the plains of North America and East Asia

2013 ◽  
Vol 10 (3) ◽  
pp. 1441-1449 ◽  
Author(s):  
G. Yu ◽  
X. Ke ◽  
H. D. Shen ◽  
Y. F. Li
Keyword(s):  
Global Warming ◽  
East Asian ◽  
Climate Extremes ◽  
Key Factors ◽  
The Past ◽  
The North ◽  
Pest Outbreaks ◽  
Precautionary Measures ◽  
The 1960S ◽  
Chemical Pesticides

Abstract. Prior to ~1880 AD locust swarms periodically raged across both the North American Plains (NAP) and East Asian Plains (EAP). After this date, locust outbreaks almost never recurred on the NAP but have continued to cause problems on the EAP. The large quantities of pesticides used in the major agriculture regions of the NAP in the late 1870s have been suggested as a possible reason for the disappearance of locust outbreaks in this area. Extensive applications of modern, i.e. more effective, chemical pesticides were also used in the granary regions of the EAP in the 1950s in an effort to reduce pest outbreaks. However, locust swarms returned again in many areas of China in the 1960s. Therefore, locust extinction on the NAP still remains a puzzle. Frequent locust outbreaks on the EAP over the past 130 yr may offer clues to the key factors that control the disappearance of locust outbreaks on the NAP. This study analysed the climate extremes and monthly temperature–precipitation combinations for the NAP and EAP, and found that differences in the frequencies of these climate combinations resulted in the contrasting locust fates in the two regions: restricting locust outbreaks in the NAP but inducing such events in the EAP. Validation shows that severe EAP locust outbreak years were coincidental with extreme climate-combination years. Therefore, we suggest that changes in frequency, extremes and trends in climate can explain why the fate of locust outbreaks in the EAP was different from that in the NAP. The results also suggest that, with present global warming trends, precautionary measures should be taken to make sure other similar pest infestations do not occur in either region.

scholarly journals Monument Boundary Definition and Exploration Pits at the Krasnyy Vostok Site in the River Kuma Basin

2020 ◽  
Author(s):  
А.В. Субботин
Keyword(s):  
Western Slope ◽  
Left Bank ◽  
North Caucasus ◽  
Mountainous Regions ◽  
The North ◽  
Boundary Definition ◽  
Northern Side ◽  
Western Side ◽  
Object Of Study ◽  
Stone Walls

В статье излагаются результаты инструментальной съемки и шурфовки на раннесредневековом городище, выявленном в начале 1970-х гг. Х. Х. Биджиевым. Городище и связанное с ним селище занимают высокое мысовое плато над каньоном левого берега р. Кумы в Карачаево-Черкесии. Площадь укрепленного городища – 4 га, селища – немногим меньше. С трех сторон городище абсолютно неприступно, с четвертой, западной, надежно защищено высоким валом и глубоким рвом. На городище и селище зафиксирован ряд западин, которые, скорее всего, являются заросшими остатками построек. Содержимое шести шурфов – каменные развалы фундаментов (?) строений и фрагменты сосудов. Керамика может быть датирована VII–X вв. н. э. Памятник являлся одним из звеньев в цепи достаточно известных (несколько десятков) укрепленных крепостей данного времени в предгорьях и горах Северного Кавказа. Строительство сети сложных оборонительных сооружений свидетельствует о высокой строительной культуре и социальной дифференциации общества в это время. The article presents the results of instrumental surveys and pitting at an early medieval site, identified in the early 1970s by Kh.Kh. Bidzhiev. The investigated site and the settlement associated with it occupy a high cape plateau above the canyon of the left bank of the river Kuma in the Karachay-Cherkess Republic. The object of study is located in 2.4 km south-west of the southern outskirts of the village Krasnovostochny. The area of the fortified site is 4 hectares, the area of the settlement is slightly less. On three sides, this site is absolutely impregnable. On the forth western side,on its western slope, it is reliably protected by a rampart of up to 6 to 7 m high and a moat of1 to 2 m deep. On the outside of the southern part of the rampart, a small outcrop of masonry constructed of the large blocks of limestone formed in the dry stone wall was discovered. The gates to the site were most likely located on the northern side of the rampart, in the place where a slight decrease was discovered, not at the southern end of the rampart (according to Bidzhiev) because no sign of an entrance was found there. The site revealed several shallow depressions of a sub-square, sub-rectangular or oval shape with a noticeable roller along the contour. There are at least 7 such depressions in the sectional area from 8 to 15 m. Probably, these depressions are the overgrown remains of the foundations of some buildings in the central part of the site. The content of 6 pits made on the territory of the site and the settlement are stone remains of the foundations (?) of ancient buildings and fragments of vessels. The collection of ceramics consists of medium-sized fragments of the walls of pottery (?) vessels, or vessels that are corrected on a wheel. The ceramics are diverse in the color of clay, density of the paste, firing, and impurities. According to the character, paste and collar shapes, ceramics can be dated to the last third of the 1st millennium AD, which does not contradict the opinion of the site’s discoverer on this issue (7th to 10th cent. AD). The examined site was one of the links in the main chain of fairly widely known (several dozen) fortified stone fortresses of this time in the foothills and mountains of the North Caucasus. Specialists know more than 130 similar stone sites, sometimes located in groups in the foothills and mountainous regions: settlements with defensive stone walls. Such small fortresses were built every 2 to 3 km along the tip of the cape above the river. The construction of a network of complex defensive structures indicates a high building culture and a social differentiation of society at the time.

Inferred seismic fault associated with the 1998 M = 6.2 Zhangbei-Shanyi earthquake, Hebei Province, China

1999 ◽  
Vol 89 (2) ◽  
pp. 550-554 ◽  
Author(s):  
Aiming Lin ◽  
Guochun Zhao ◽  
Guozhe Zhao ◽  
Xiwei Xu
Keyword(s):  
Seismic Data ◽  
Active Fault ◽  
Lateral Displacement ◽  
Displacement Component ◽  
The North ◽  
Seismic Fault ◽  
Direction Change ◽  
Western Side ◽  
Northwest Region ◽  
Beijing China

Abstract The shallow, Ms = 6.2, 1998 Zhangbei-Shanyi earthquake that affected the northwest region of Beijing, China, occurred at the intersection of two active fault zones, located on the north and east edges of the Ordos tableland. A detailed map of the intensity distribution of damaged building shows that the most damaged area was centered 8 to 10 km away from the epicenter, including an ellipsoidal region with a strike of NNE, where more than 70 to 90% of buildings were destroyed. Many chimneys and gate pillars were broken and fell toward the SSE-SSW direction in the western side of the most damaged area and to the NNE-NNW direction in the eastern side. Aftershocks were also concentrated in the most damaged area. It is inferred that the boundary of the downfallen direction change is the surface trace of the seismic fault. Based on the seismic data, the distribution of damaged buildings, and the downfallen directions of 70 chimneys and gate pillars, it is identified that the seismic fault is a thrust fault striking NNE and dipping 40° to 50° northwest with a large right-lateral displacement component.

REAL-TIME 3D IMAGING OF COMPLEX TURBIDITIC RESERVOIR ARCHITECTURE

2021 ◽  
Author(s):  
Supriya Sinha ◽  
◽  
Karol Riofrio ◽  
Arthur Walmsley ◽  
Nigel Clegg ◽  
...  
Keyword(s):  
Real Time ◽  
Structural Control ◽  
Seismic Signal ◽  
Time Inversion ◽  
3D Inversion ◽  
Reservoir Architecture ◽  
The North ◽  
Oil Water ◽  
3D Em ◽  
Accurate Imaging

Siliciclastic turbidite lobes and channels are known to exhibit varying degrees of architectural complexity. Understanding the elements that contribute to this complexity is the key to optimizing drilling targets, completions designs and long-term production. Several methods for 3D reservoir modelling based on seismic and electromagnetic (EM) data are available that are often complemented with outcrop, core and well log data studies. This paper explores an ultra-deep 3D EM inversion process during real-time drilling and how it can enhance the reservoir understanding beyond the existing approaches. The new generation of ultra-deep triaxial EM logging tools provide full-tensor, multi-component data with large depths of detection, allowing a range of geophysical inversion processing techniques to be implemented. A Gauss-Newton-based 3D inversion using semi-structured meshing was adapted to support real-time inversion of ultra-deep EM data while drilling. This 3D processing methodology provides more accurate imaging of the 3D architectural elements of the reservoir compared to earlier independent up-down, right-left imaging using 1D and 2D processing methods. This technology was trialed in multiple wells in the Heimdal Formation, a siliciclastic Palaeocene reservoir in the North Sea. The Heimdal Fm. sandstones are generally considered to be of excellent reservoir quality, deposited through many turbiditic pulses of variable energy. The presence of thin intra-reservoir shales, fine-grained sands, heterolithic zones and calcite-cemented intervals add architectural complexity to the reservoir and subsequently impacts the fluid flow within the sands. These features are responsible for heterogeneities that create tortuosity in the reservoir. When combined with more than a decade of production, they have caused significant localized movement of oil-water and gas-oil contacts. Ultra-deep 3D EM measurements have sensitivity to both rock and fluid properties within the EM field volume. They can, therefore, be applied to mapping both the internal reservoir structure and the oil-water contacts in the field. The enhanced imaging provided by the 3D inversion technology has allowed the interpretation of what appears to be laterally stacked turbidite channel fill deposits within a cross-axial amalgamated reservoir section. Accurate imaging of these elements has provided strong evidence of this depositional mechanism for the first time and added structural control in an area with little or no seismic signal.

Grim's Bank, Padworth, Berkshire

Antiquity ◽  
1943 ◽  
Vol 17 (68) ◽  
pp. 188-195
Author(s):  
B. H. St. J. O'Neil
Keyword(s):  
The Other ◽  
Present Writer ◽  
Recent Past ◽  
The West ◽  
The Road ◽  
The North ◽  
Northern Side ◽  
Western Side

The immediate environs of Silchester consist of fields, which are either now under plough or else have been arable for many years in the recent past. Consequently there are few, if any, traces there of the Roman roads which led from the various gates to Dorchester, Speen and Cirencester, Sarum, Winchester, and London. A mile or more to the north and northwest of the Roman town, however, there is a belt of land, which is largely heathland except where trees have been planted. Here there are clear indications of the line of two Roman roads, one from the west gate, west-northwest to Speen and Cirencester, the other from the north gate to Dorchester (Oxon.)The road to Speen (FIG. I) was formerly thought to follow closely the modern road along the northern side of Silchester Common and thence to run along the straight county boundary between Berkshire and Hampshire. In recent years, however, Mr O. G. S. Crawford has shown that the road, instead of following this traditional line, ran west-northwestward to cross the river Kennet near Brimpton Mill. It is traceable as a raised camber or a deep hollow way from Catthaw Lands Copse, about half-a-mile from the west gate of Silchester, to the western side of Hungry Hill. Further west, in Decoy Plantation, and again beyond the road from Padworth Common, i.e. in Keyser's Plantation, it is clearly seen as a broad cambered way (o.s. 641-1. Berkshire XLIV, SE, Hampshire IV, SE). Beyond this point the present writer has not followed it, but Mr Crawford has noted its continuation.

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