ГЕОЛОГО-ГЕОМОРФОЛОГИЧЕСКИЕ УСЛОВИЯ ФОРМИРОВАНИЯ И СОХРАННОСТИ РОССЫПЕЙ ЗОЛОТА В БЕЛЬСКОЙ МЕЖГОРНОЙ ДЕПРЕССИИ (ЮЖНЫЙ УРАЛ)

The Hongshijing gold deposit, which occurs in the Middle and Late Carboniferous volcanic and pyroclastic rocks, is of the brittle-ductile shear zone type controlled by a rift belt. The Hongshijing gold deposit is one controlled by a brittle shear zone located in the Late Paleozoic rift zone. The altered-rock type and quartz type orebodies are contained in the gold-bearing formation, which consists of basalt and tuffaceous sandstone. The major mineralizing stage is at 267 - 261 Ma and reiteration mineralizing stage at 220 - 209 Ma. The ore minerals include pyrite, magnetite, copper, bornite, ferrohydrite, native gold, and the gangue minerals include quartz, sercite, calcite, Fe-dolomite, leucoxene, anorthose, biotite, baria, cajuelite, and agustite. The wall rock alteration associated with gold mineralization comprises silicification, carbonization, pyritization, sericitization and chloritization. The contents of gold are 2.4 × 10−9 in the gold-bearing formation, 5.7 × 10−9 in the tuffaceous sandstone and 1.4–1.5 × 10−9 in the basalt. Au is associated with Te, Se, Ni, Cu. Au = 74.331 × Te +0.0335 × Ni−0.0211 × Cu-2.650. Geochemical investigations revealed that the mineralizing materials came from the basalt and tuffaceous sandstone in the gold-bearing formation. Under the action of ductile brittle shear structure, the gold-bearing formation was metamorphosed and altered, and the ore-forming materials activated, migrated and mineralized. The mineralizing fluid shows three mineralizing stages, with the characteristics of middle to low temperature (381-115°C) and middle to low mass fractions of NaCl (2.18%-16.77%). The fluid is of the Ca2+ -Mg2+ -Na+ -Cl− type and H2O-NaCl system. According to the data from hydrogen and oxygen isotopic composition (δD = −114.6%= −68.8%, δ18OH 2O = −2.47%−5.91%), the conclusion can be drawn that the mineralizing fluid of the Hongshijing gold deposit was a kind of mixed hydrothermal solution composed mainly of meteoric water, magmatic water and formation water in basalt and tuffaceous-sandstone or metamorphic water. The results show the mineralizing fluid and mineralizing materials came from the basalt and suffaceous-sandstone in the gold-bearing formation in Late Variscan orogeny. Under the action of brittle shearing, the gold-bearing formation was metamorphosed and altered, and the ore-forming material activated, migrated and mineralized withT andP going down and changes in pH, Eh,f O 2 andf S 2 under the earth’s surface from 1.57 to 2.25 km.

Mineralogy, geochemistry and U-Pb zircon age of the Karaotkel Ti-Zr placer deposit, Eastern Kazakhstan and its genetic link to the Karaotkel-Preobrazhenka intrusion

Placer gold along the upper portions of Gold Creek, near Deer Lodge, Montana, occurs in Pliocene(?) fossil alluvial placers, Pleistocene till, and alluvium. The upper Gold Creek placers yielded an estimated 175 to 200 kg gold during 1890 to 1990. The gold probably originated in veins, skarn, or replacement deposits in Paleozoic and Mesozoic sedimentary units near the contact with Late Cretaceous granodiorite of the Royal stock. Gold was initially concentrated in alluvial placers along the ancestral Gold Creek valley during late Tertiary (Pliocene) time. Pleistocene glaciers scoured the Pliocene placers from most parts of the valley, although the fossil placers were locally buried beneath till and gold was also incorporated into till that was deposited farther down valley. Gold from Pliocene and Pleistocene placers has locally been reconcentrated into alluvium as a result of postglacial stream incision.The placer gold occurs as coarse-sized, oval to elongate grains characterized by rounded protuberances and inclusions of quartz and sulfide minerals. In polished section the grains have alternating convex and concave borders interrupted by pits and embayments. Grain borders and interiors of embayments display supergene gold rims averaging 98.8 percent Au. Microprobe analysis of cores indicate average compositions of 83.6 percent Au and 16.5 percent Ag and spectrographic data indicate a trace element signature enriched in Cu, Pb, and Sb, which is compatible with derivation from mesothermal plutonic lode deposits associated with the Royal stock.

Mineral resources have been important to the Alaskan economy for hundreds of years. The Indians, Eskimos, and Aleuts used gold, copper, and other metals for jewelry, utensils, and weapons and as items of trade. The Russians, who arrived in 1728, showed only minor interest in minerals, focusing instead on furs. Nonetheless, records show that they mined iron ore on the Kenai Peninsula in 1793 and located gold there in 1834. In addition, the Russians were aware of copper-rich occurrences in the Copper River basin.The mining industry grew rapidly in Alaska after the United States purchased the region from Russia in 1867. By 1870, gold was being mined near Windham Bay and near Sitka, in southeastern Alaska. The first major hard-rock gold mining began at the Alaska-Juneau, Perseverance, and Treadwell mines near present-day Juneau following the discovery of placer gold near tidewater in 1880. Significant placer mining operations for gold soon spread northward into districts such as Fairban ks, Nome, Iditarod, and Circle.The exploitation of mineral resources, particularly gold, influenced the settlement and development of much of the state. Major cities such as Nome, Fairbanks, and Juneau, the capital, were originally built around early mining camps. By1996, more than 33 million oz of gold, as well as significant amounts of copper, lead, zinc, silver, and platinum-group elements, had been produced. In addition, there has been minor production of nickel. tin, mercury, and uraniumAlaska is presently experiencing a renaissance in mining on federal, state, private, and native lands. From 1990 to 1996, the minerals industly had an annual value of approximately $600 million, with a record 1 billion in 1996. Nearly 3,500 year-round jobs were directly attributed to the minerals industq. Looking forward into the twenty-fi rst centu1y, the outlook is even better. Major mines such as Heel Dog are in production. Recently completed exploration at the Red Dog sedimenta1y exhalative deposit has significantly expanded the reserve base and major mine expansion is contemplated. The Nixon Fork gold skarn deposit was put into production in 1995, with the first ore poured in November. The Greens Creek mine resumed production in late 1996, following renewed exploration and development of the volcanogenic massive sulfide deposit. The Fort Knox gold mine, near Fairbanks, is under construction and is scheduled to yield ore by late 1996. In southwest Alaska exploration success has yielded a significant gold resource at Donlin Creek. In addition, the Kensington-Jualin project is

Analysis of the formation conditions of Quaternary gold placers in the mountain area of the Southern Urals on the example of the Suleymenskaya multilayer placer shows that the most productive are the Eopleistocene and Middle Neopleistocene placer cycles associated with the final phase of the continuously intermittent neoorogenic rise of the territory. At the same time, the productivity of placers increases with the increase in the scale of fluvial processing of sediments of the Eopleistocene paleo-cleft and the transition of placers to the Middle Neopleistocene. The source of gold of the Suleymenskaya placer is the zone of gold ore mineralization in the northern part of the Tungatarovskiy fault. Prospects for expanding the raw material base of the territory are associated with the productive sediments of buried Eopleistocene paleo-cleft, coinciding with the zones of goldsulfide mineralization.

A brief history of placer formation and patterns of formation of river valleys in the Mesozoic and Cenozoic are considered. The evolution of the hydraulic net-work, its inception along weakened ore-bearing zones determines the patterns of the position of gold placers in the Western Urals. The formation of gold-bearing placers within the structural-erosion depression is due to the sources of gold, the conditions of their destruction, the erosional incision of river valleys along thrust zones within the Visher-Visim depression. Five types of potentially productive gold placers have been identified, depending on the ratio of the erosional incision of river valleys and gold-bearing eluvium.

Oligocene-Early Miocene river incision near the first bend of the Yangze River: Insights from apatite (U-Th-Sm)/He thermochronology

This paper presents a numerical petroleum systems model for the Jurassic‐Tertiary Austral (Magallanes) Basin, southern Argentina, incorporating the western part of the nearby Malvinas Basin. The modelling is based on a recently published seismo‐stratigraphic interpretation and resulting depth and thickness maps. Measured vitrinite reflectance data from 25 wells in the Austral and Malvinas Basins were used for thermal model calibration; eight calibration data sets are presented for the Austral Basin and four for the Malvinas Basin. Burial history reconstruction allowed eroded thicknesses to be estimated and palaeo heat‐flow values to be determined. Six modelled burial, temperature and maturation histories are shown for well locations in the onshore Austral Basin and the western Malvinas Basin. These modelled histories, combined with kinetic data measured for a sample from the Lower Cretaceous Springhill Formation, were used to model hydrocarbon generation in the study area. Maps of thermal maturity and transformation ratio for the three main source rocks (the Springhill, Inoceramus and Lower Margas Verdes Formations) were compiled. The modelling results suggest that deepest burial occurred during the Miocene followed by a phase of uplift and erosion. However, an Eocene phase of deep burial leading to maximum temperatures cannot be excluded based on vitrinite reflectance and numerical modelling results. Relatively little post‐Miocene uplift and erosion (approx. 50–100 m) occurred in the Malvinas Basin.Based on the burial‐ and thermal histories, initial hydrocarbon generation is interpreted to have taken place in the Early Cretaceous in the Austral Basin and to have continued until the Miocene. A similar pattern is predicted for the western Malvinas Basin, with an early phase of hydrocarbon generation during the Late Cretaceous and a later phase during the Miocene. However, source rock maturity (as well as the transformation ratio) remained low in the Malvinas Basin, only just reaching the oil window. Higher maturities are modelled for the deeper parts of the Austral Basin, where greater subsidence and deeper burial occurred.

Todays highly parameterized large-scale distributed computing systems may be composed of a large number of various components (computers, databases, etc) and must provide a wide range of services. The users of such systems, located at different (geographical or managerial) network cluster may have a limited access to the systems services and resources, and different, often conflicting, expectations and requirements. Moreover, the information and data processed in such dynamic environments may be incomplete, imprecise, fragmentary, and overloading. All of the above mentioned issues require some intelligent scalable methodologies for the management of the whole complex structure, which unfortunately may increase the energy consumption of such systems. An optimal energy utilization has reached to a point that many information technology (IT) managers and corporate executives are all up in arms to identify scalable solution that can reduce electricity consumption (so that the total cost of operation is minimized) of their respective large-scale computing systems and simultaneously improve upon or maintain the current throughput of the system. This book in its eight chapters, addresses the fundamental issues related to the energy usage and the optimal low-cost system design in high performance ``green computing systems. The recent evolutionary and general metaheuristic-based solutions for energy optimization in data processing, scheduling, resource allocation, and communication in modern computational grids, could and network computing are presented along with several important conventional technologies to cover the hot topics from the fundamental theory of the green computing concept and to describe the basic architectures of systems. This book points out the potential application areas and provides detailed examples of application case studies in low-energy computational systems. The development trends and open research issues are also outlined. All of those technologies have formed the foundation for the green computing that we know of today.

Geological Evolution of the Red Sea: Historical Background, Review, and Synthesis

Abstract. The Beishan Mountain spans three provinces ‐ Gansu, Xinjiang and Inner Mongolia, having an area of 120,000 km2 Tectonically, it transverses three different tectonic units, i.e. Siberia, Kazakhstan and Tarim plates, and is composed of nine ter‐rains with widely exposed Precambrian and Paleozoic strata, complex structures, intensive magmatic activities and widespread ore deposits. It is not only a main part of Tianshan‐Yinshan‐Great Hinggan metallogenic belt in China, but also a key to under‐stand the evolution of central‐Asian orogenic system.At present, more than 100 gold deposits and prospects have been discovered, explored and mined, among which Nanjinshan, Mazhuangshan, Liushashan, Jinwozi, Zhaobishan and Xiaoxigong are the most important ones. Based on the host rocks and the geological features, all these gold occurrences can be subdivided into three groups (or types): (1) hosted by Carboniferous or Permian volcanic or subvolcanic rocks; (2) hosted by or related to plutonic intrusions; and (3) hosted by Precambrian metamorphic rocks. The first group includes the Mazhuangshan gold deposit, which occurs in Hercynian quartz por‐phyry and rhyolite porphyry as gold‐bearing quartz veins. The second group is composed of the Liushashan, Nanjinshan Zhaobishan and Jinwozi gold deposits. Gold mineralization at these four deposits occurs within Hercynian granitoids intrusion: or late Paleozoic sedimentary rocks as quartz veins, veinlets and altered rocks. The Xiaoxigong gold deposit belongs to the third group, and is hosted by Precambrian schist, amphibolite and migmatite as quartz veins and altered rocks.Isotopic age dating data, geological and geochemical evidence suggest that most of the groups 1 and 2 gold deposits were generated during the emplacement of the Hercynian or partly Indosinian intrusions. These intrusions may provide both heat and metals for groups 1 and 2 deposits. In contrast, although the formation is closely related to the Hercynian magma‐tism, the ore‐forming materials of the group 3 deposits may not only come from the intrusions, but also from the Precambrian metamorphic rocks.

Shallow shale gas reservoirs in mountainous terrains are influenced by "low formation pressure, significant variations in burial depth, steep formation dips, and the presence of fractures and microstructures", posing challenges in aligning well types and development strategies with geological characteristics. This research introduces an innovative "tectonics-driven, multifaceted integration" approach to development and well optimization techniques. Utilizing the Petrel platform, this study constructed a detailed 3D geomechanical model for a geologically complex body, incorporating various stress patterns. The model delineates the area based on gas enrichment status, tectonic styles, stress regimes, and fracture development. Comparative analyses of stress distribution around the wells in different drilling orientations were conducted using near-wellbore geomechanical models. Additionally, production capacity evaluations and numerical simulations were employed to analyze the effectiveness of different development strategies and well types. The near-wellbore geomechanical model indicates that well placement along tectonic contours (at certain angles to the minimum horizontal principal stress) enhances wellbore stability and ensures a more uniform stress distribution conducive to homogenous modifications. Simulations reveal minimal differences in production capacity under identical fracturing processes, advantageous for efficient "water drainage and gas production". This well distribution method suits the extensively developed steep zones within the study area. Addressing the challenges in strike-slip to thrust transition zones and thrust areas, where bedding planes and low-angle fractures are prone to activation and horizontal wells face difficulties in vertical layer penetration, a pilot test for a comprehensive three-dimensional development strategy using clustered directional wells from a controlled platform was conducted. The feasibility of deploying directional wells in reverse fault stress regime zones was validated through simulations. Ultimately, considering the life-cycle benefit goals and maximized reserve utilization, the study advocates for a "tectonics-driven, multifaceted integration" concept, leading to the creation of a decision-making framework for a capacity-focused, integrated development model. Based on the mechanistic understanding that complex structure and strong non-homogeneity are essential in forming complex fracture networks, this study challenges the traditional practice of orienting wells along the direction of minimum horizontal principal stress. It innovatively proposes the method of well placement along the direction of tectonic contours or principal controlling faults, offering valuable insights for the production of other unconventional resources.

<p>The Meso/Cenozoic geodynamic evolution of the Calabria Peloritani Arc (CPA) has been, and is still, hotly debated, this sector of the Apennine chain being an exotic continental ribbon scraped off from its original position (European Plate) during the south-eastward migration of the Apenninic slab.</p><p>The Southern sector of the Arc (Peloritani Mts.) has been analysed using a multidisciplinary approach. An analysis of pre-, syn- and late-orogenic siliciclastic deposits (Militello Fm, Frazzanò Flysh, Capo d’Orlando Fm) is essential for our understanding of how orogenic phases developed through the Late Cretaceous and Palaeogene. Biostratigraphical constraints reveal a multi-step compressive history, with discrete events (Alpine phase – Balearic phase – Apenninic phase)</p><p>The Northern sector of the Arc is conversely less well known, namely with regards to its pre-Serravallian history, due to the lack of continuous exposures of the Meso/Cenozoic sedimentary cover. One remarkable exception is the Longobucco Basin (Sila Greca, CS), where a Meso/Cenozoic succession covers unconformably the igneous and metamorphic Hercynian basement.  A geological mapping project of the Longobucco Basin is proving instrumental in constraining the Cenozoic dynamics of this sector of the Arc. In particular, the Paludi Fm has been analysed. This is a multifaceted lithostratigraphic unit, made of conglomerates/breccias, reddish marls and arenaceous turbidites, whose composition testifies the dismantling of an orogen. This unit is in turn crosscut and deformed by north eastward verging thrusts dated as Burdigalian by Vignaroli and co-authors (2014), therefore it also apparently predates a younger tectonic phase (see the Frazzanò Flysch in Southern CPA for an analogy).</p><p>Despite the regional importance of this Unit, its age is highly debated in the literature, ranging from the Late Cretaceous to the Aquitanian, according to different Authors. In this light, a biostratigraphic study of this unit ( nannoplancton, micro- and macroforaminifer)a, has been performed.</p><p>Field mapping has revealed a wealth of sedimentary structures ascribable to ductile and or/brittle-ductile deformation, typical of mass transport deposits (i.e. slumps, non-tectonic thrusts, pseudo sigma structures, asymmetric rootless folds and ductile shear zones). The occurrence of olistostromes, with evidence of syn-emplacement deformation, has been mapped. These plastically deformed bodies are Late Cretaceous in age (Aptian to Maastrichtian). They document lost parts of the succession, eroded during the uplift phases and cannibalized within a younger part of the succession, which must therefore be post-Cretaceous.</p><p>Being the age obtained from micropaleontological data comprised between the Eocene and the Oligocene, we must preliminarily ascribe the emplacement stage to an alpine phase. The Burdigalian thrusting event predates the opening of the Tyrrhenian sea and the detachment of the CPA from the Corsica-Sardinia block. It cannot therefore be ascribed to an Apenninic s.s. phase. We attribute this thrusting event to an earlier phase (Balearic phase) related to the Corsica-Sardinia block rotation.     </p><p>Vignaroli G., Minelli L., Rossetti F., Balestrieri M.L. & Faccenna C. (2012) - Tectonophysics, 538, 105-119.</p>

Persistent oxygen-depleted zones in the ocean are known primarily from enclosed basins in temperate regions or the open ocean (including oxygen minimum and limiting zones) (1). However, little is known about the possibility of such zones forming in tropical coastal domains, even though the combination of warmer temperatures and complex geological features in some tropical regions makes their occurrence more likely (1, 2). Here, we report two subsurface oxygen-depleted zones within deep (>490 m) depressions of the Red Sea's Difaht Farasan-a carbonate platform hosting the world's third largest contiguous tropical coral reef system. One zone maintains suboxic oxygen levels (∼11-14 µmol O2 kg⁻¹), while the other sustains oxygen levels below detection (<2 µmol O2 kg⁻¹). The suboxic zone shows no fixed nitrogen loss, while the near-anoxic zone hosts anaerobic microbial populations and shows signs of nitrogen loss. We propose that the warm and saline environment of the Red Sea interacts with the semienclosed depressions to restrict vertical mixing, limiting oxygen resupply at depth. However, unlike most other oxygen-depleted zones, our deep-sea vehicle surveys demonstrate that these zones support resistant aerobically respiring taxa, indicating an unusual capacity to reduce aerobic oxygen demands at high temperatures (>21 °C). Targeted exploration of deep tropical coastal environments is crucial for determining whether similar zones exist beyond the Red Sea and understanding their potential responses to climate change.

Basinward propagation of fold and thrust belts is a crucial geological process accommodating Cenozoic crustal shortening within the India‐Eurasia collision zone. Anticlinal growth strata in the southern Chaiwopu Basin (a piggyback basin) of the northern Chinese Tian Shan foreland record basinward encroachment of the Tian Shan along the Junggar Frontal Thrust Fault. A new magnetostratigraphic section constrains the onset of syntectonic growth strata at circa 6.4 Ma and suggests synchronous basinward thrusting and propagation of the Tian Shan. The intense alluviation in the southern Chaiwopu Basin ceased at circa 0.55 Ma due to significant anticlinal growth and its resultant river incision. More recent anticlinal growth and deformation during the late Quaternary are revealed by folded river terraces developing across the anticline. The terrace height profile indicates that terrace T1Hhas been vertically offset about 0.6 m by thrust faulting since its formation at about 7 Ka. The stratigraphic and geomorphic data presented in this work are helpful to understand the initiation of thrust‐related folding, as well as aggradation and subsequent incision, in foreland basins of the Tian Shan in relation to the India‐Asia collision.