Different Types Of Deposits Research Articles

Non-Performing Assets in Schedule Commercial Banks

Banking industry plays an important role in any country. They provide different types of loans and offer different types of deposits. If banks are weak, they are unable to provide loans. So this is may impact countries economy. To become banks weak so many reasons are there. One of the main reasons is non-performing assets. Non-performing assets refer to people are unable to pay the loans, at that time they become NPAS to the banks. When NPAS arise in banks; they show their impact on banks. Banks net profits are decrease. They are unable to provide loans to different sectors. So banks destruction shows so much impact on different sectors

Across the River. The Cemetery in Dolina and New Aspects of the Late Urnfield Culture in Croatian Posavina and Northern Bosnia

The site of Dolina in the Croatian region of Posavina has been investigated since 2009 under the leadership of the Institute of Archaeology in Zagreb. In previous excavations five tumuli with one or two cremation deposits of different types (urned, scattered cremation remains, or with an organic container) could be detected. On the basis of characteristic grave goods (bronze pins and fibulae, helmet parts), the burials are dated to the 9th-8th century BC or in the stage Ha B3-Ha C1. Typical of Dolina, but also of other sites in Croatia and Bosnia along the middle course of the Sava River (e.g. Donja Dolina), is the ensemble of finds (jewellery, weapons and ceramics) of different regional origin, which underlines the specific position of this region at the interface between the Carpathian Basin to the north, the Alps to the west, the Balkans to the south and the lower Danube to the east. Vessels with incised zigzag motifs from Tumuli 6 and 8 reveal communication with the neighbouring area of northern Bosnia. Similar ornamentation appears there in contemporaneous settlement layers (at Vis and Zecovi) and in the corresponding cremation burials in flat graves (Petkovo Brdo and Mekota). However, the establishment of tumuli at Dolina, and various burial rites with different grave goods, emphasise a strong local component and a distinct individualisation of the graves, i.e. as buried members of a particular but heterogeneous community.

Composition and distribution of REE in ferromanganese crusts of the Belyaevsky and Medvedev seamounts in the Sea of Japan

This paper presents the results of the integrated study of ferromanganese crusts from the Belyaevsky (Central Basin) and Medvedev (Honshu Basin) seamounts from the Sea of Japan. The study of the mineral composition using powder diffraction and optical and electron microscopy showed that the crusts are made up of todorokite, birnessite, and pyrolusite minerals typical of hydrothermal ferromanganese deposits of the World Ocean. The composition of the ferromanganese crusts from the Sea of Japan was determined by ICP-MS and ICP-OES. The contents of Mn, Fe, Co, Cu, Ni, and other major and trace elements indicate the hydrothermal genesis of the crusts. The obtained data on the composition of ferromanganese crusts of the Sea of Japan, as well as their comparison with different types of deposits of the World Ocean, suggest the endogenic genesis of the studied crusts. However, the REE and Y distribution patterns testify to a significant admixture of hydrogenic matter, which participated in the growth of ferromanganese crusts from the Belyaevsky and Medvedev seamounts.

The reasons and adverse effect of internal diesel injector deposits formation

The paper report on the state of affairs so far in the scope of internal diesel injection deposits (IDID) issue affecting modern diesel high pressure common rail (HPCR) systems. Different types of deposits have been described and the factors supporting their creation. These deposits have been extensively studied to understand their formation mechanisms and composition. To this end an engine test procedure was developed to assess the deposit forming tendencies of various types. Findings of two long time dynamometer engine tests in which the course of the IDID formation and HPCR performance impairing was followed by measurement different engine parameters have been reported. Performance evaluation of HPCR injectors before and after tests have been presented also.

Hydrothermal fluids in epithermal and porphyry Au deposits in the Central Slovakia Volcanic Field

Abstract The Neogene Central Slovakia Volcanic Field in the Carpathian arc contains various Au deposits, hosted by central zones of large andesite stratovolcanoes. Fluids involved in mineralization have been studied at three different types of deposit, mostly by fluid inclusion and stable isotope techniques. The Rozália mine in the Štiavnica stratovolcano hosts intermediate sulphidation-style Au–Ag epithermal mineralization in subhorizontal veins related to hydrothermal activity during an early stage of caldera collapse. Associated fluids of low salinity underwent extensive boiling at 280–330 °C on transition from suprahydrostatic towards hydrodynamic conditions at shallow depths ( c. 550 m) from fluids of mixed magmatic and meteoric origin. The Kremnica ore field hosts a large system of low sulphidation-style Au–Ag veins contemporaneous with rhyolite magmatism and situated on resurgent horst faults. Fluids were of low salinity, predominantly of meteoric origin, and showed gradual decrease in temperature along the system ( c. 270–140 °C) related to a decrease in erosion level from c. 500 to c. 50 m. The Biely Vrch Au-porphyry deposit in the Javorie stratovolcano is associated with quartz stockwork in diorite porphyry intrusion. The major type of ore-bearing fluid was high temperature magmatic vapour (720–<380 °C) accompanied by Fe-rich salt melt. Gold precipitated in a high-temperature but low-pressure subvolcanic environment. Supplementary material: Stable isotope data and fluid inclusion microthermometric data are available at http://www.geolsoc.org.uk/SUP18752 .

Regional mineral exploration targeting for gold and nickel deposits using crustal electrical conductivity variations determined using the magnetotelluric method

Current ideas on regional prospectivity analysis emphasize the importance of major fault structures and in particular (palaeo) suture zones within and between cratonic blocks. These features represent deep penetrating zones of enhanced permeability encouraging the passage of potentially mineralizing brines and melts. Such features have been linked with the occurrence of several different types of deposit, notably nickel-sulfide and gold deposits. Detection of such geological features requires mapping variations in physical properties at lower crustal and mantle depths. As part of a study on regional prospectivity, magnetotelluric (MT) surveys have been completed in several prospective Proterozoic and Archean terrains in Western Australia (Kimberley Craton and surrounding orogenic belts, Musgrave Province, Capricorn Orogen, Yilgarn Craton). . These data, which have been interpreted in association with potential field, seismic, geological and geochemical data, demonstrate that MT surveys can be used to identify features indicative of regional-scale prospectivity based on variations in the electrical conductivity of the crust and upper mantle. For example, a survey in the southern Yilgarn Craton has identified lateral changes in deep crust and upper mantle conductivity structure consistent with palaeo-cratonic boundaries inferred from studies using isotope geochemistry. The MT data allow the boundaries to be accurately located; the isotopic results being limited by the spatial distribution of outcrops of suitable lithotypes. The survey areas in Western Australia are geographically remote and often environmentally and culturally significant. MT surveys represent a comparatively cheap means of evaluating regional prospectivity, whilst causing minimal cultural and environmental disturbance. It is argued that MT data comprise useful pre-competitive data type and that Governments should consider this type of survey as a complement to the more common potential field surveys.

In vitro binding of [3H]PIB to human amyloid deposits of different types

Systemic amyloidosis is caused by extracellular deposition of insoluble fibrillar proteins arranged in β-pleated sheets. [11C]PIB has been used in PET studies to assess Aβ deposition in brain of patients with Alzheimer’s disease (AD). The possibility to visualize other types of amyloid deposits with [11C]PIB would be of potential clinical importance in early diagnosis and for following therapeutic effects. In the present study, we evaluated in vitro binding of [3H]PIB to tissues containing transthyretin (ATTR), immunoglobulin light-chain (AL), amyloid protein A (AA) and Aβ amyloid. We found significantly higher binding of [3H]PIB in tissue from systemic amyloidoses than in control tissue, i.e. 4.7 times higher (p < 0.05). [3H]PIB showed the highest affinity to cortex of AD brain (IC50 = 3.84 nM), while IC50 values were much higher for ATTR, AA and AL type of amyloidosis and large variations in affinity were observed even within tissues having the same type of amyloidosis. Extraction with guanidine-HCl, which disrupts the β-sheet structure, decreased the protein levels and, concomitantly, the binding of [3H]PIB in all four types of amyloidoses.

The prospective and hypothetical areas of zinc and/or lead ores in different types of deposits beyond the Upper Silesia Zn-Pb Ore District in Poland

Streszczenie Największe szanse na udokumentowanie zasobów perspektywicznych złóż rud Zn-Pb w Polsce występują w obszarze o powierzchni około 2000 km2 usytuowanym na północ od udokumentowanych złóż siarczkowych Zn-Pb regionu zawierciańskiego. Wydzielone zostały tam cztery rejony perspektywiczne dla wystąpień złóż rud siarczkowych Zn-Pb typu Mississippi Valery Type (MVT) w utworach węglanowych triasu (wapień muszlowy) i dewonu. Za najbardziej obiecujący uznano obszar na NW od Myszkowa oraz obszar na SE od Koziegłowów. Jednak ze względu na słabe rozpoznanie wiertnicze zasoby md Zn-Pb są trudne do oszacowania. Celowe jest przeprowadzenie dalszych prac geofizycznych (np. metodą 1P), które w przypadku pozytywnych wyników należałoby rozpoznać wierceniami. W cechsztyńskiej formacji miedzionośnej na monoklinie przedsudeckiej (wokół obszaru złożowego Lubin- -Sieroszowice), na peryklinie Żar (na SW od Zielonej Góry) i w niecce północnosudeckiej (wokół złóż Konrad i Lena-Nowy Kościół oraz na N od Zgorzelca) znanych jest kilka obszarów występowania bogatej mineralizacji Pb-Zn. Jednak ze względu na dużą głębokość zalegania mineralizacji, okruszcowanie to może stanowić jedynie kopalinę towarzyszącą wydobywaną przy okazji eksploatacji rud Cu-Ag. Jednak pomimo znacznych zasobów cynk jak dotychczas nie jest odzyskiwany w procesach przeróbczych jak i metalurgicznych przez KGHM Polska Miedź S.A. Liczne drobne wystąpienia mineralizacji Zn-Pb i Pb w Sudetach, G. Świętokrzyskich oraz w strefie kontaktu bloku małopolskiego z górnośląskim nie mają znaczenia ekonomicznego jednak stanowią ważne przesłanki dla dalszych poszukiwań, które mogą doprowadzić do odkrycia złóż siarczkowych Zn i/lub Pb, różnorodnych pod względem genetycznym (stratoidalne, hydrotermalne żyłowe i/lub brekcje, kontaktowo-metasomatyczne, SEDEX) jak i zasobowym.

The role of AMD secondary minerals in controlling environmental pollution: Indications from bulk leaching tests

Weathering of sulphide minerals produces a large variety of Fe-oxide-bearing ochreous, varicoloured precipitates and efflorescences of variably soluble sulphate salts. These secondary minerals play an important role in acid mine drainage processes and, more generally, for environmental pollution, since they can be either a sink or a source for acidity and toxic metals. At Libiola mine, eastern Liguria (Italy), the secondary minerals directly form through precipitation from acid sulphate waters within waste-rock dumps and outcropping mineralized bodies as well as within streams and runoff channels. Within waste-rock dumps they are present mainly as cement, filling the inter-clast porosity, and/or as coating and ephemeral efflorescences on the outcropping surfaces. Their stability represents a major environmental issue due to the potential importance of these phases in controlling metal distribution in the surface environment. This paper presents a detailed mineralogy and geochemistry characterisation of these materials, investigating the tendency for different types of secondary minerals (hardpans, ochreous consolidated precipitates, ochreous colloids, non ochreous colloids) to release metals after a simple mixing with deionised water for 12days. Within the different types of deposits, hardpans showed the lowest tendency to release metals, in contrast to ochreous colloids and ochreous concretions that gave the highest concentrations.Nickel was the element most easily extracted by this treatment, even from non-ochreous colloids, while iron was much less readily leached. Dissolution experiments carried out on efflorescent sulphate salts demonstrated that these materials have a strong acid producing affinity which led to their complete dissolution. These results indicate that secondary phases associated with acid mine drainage can play an important role in controlling trace metal mobility, acting either as scavengers, to remove metals, from solutions or also as secondary sources of metal contamination during the interaction of these materials with surface waters.

Productivity and efficiency dynamics in Indian banking: An input distance function approach incorporating quality of inputs and outputs

SUMMARYBanking technology is typically characterized by multiple inputs and multiple outputs that are associated with various attributes, such as different types of deposits, loans, number of accounts, classes of employees and location of branches. These quality differentials in inputs and outputs are mostly ignored in empirical studies. These omissions make the practical value of productivity studies in organizations like banks questionable because quality is a key component of performance. This paper proposes using hedonic aggregator functions (as a tool of aggregating inputs and outputs with quality attributes) within an input distance function framework and analyzes the impact of banking deregulation on efficiency and total factor productivity (TFP) change in the Indian banking industry using panel data for the period 1996–2005. Empirical results indicate that banks have improved their efficiency (from 61% in 1996 to 72% in 2005) during the post‐deregulation period, and the gain in efficiency of state‐owned banks has surpassed that of private banks. Improvement in capital base, as indicated by increased capital adequacy ratio, played an important role in ushering efficiency gain. The return to scale estimate suggests that state‐owned banks are operating far above their efficient scale and cost savings can be obtained by reducing their size of operations. Overall, TFP growth was above 3.5% annually. Both technical progress and technical efficiency change consistently played an important role in shaping TFP growth. Copyright © 2010 John Wiley &amp; Sons, Ltd.

Composition Typomorphic Characteristics of Pyrite in Various Genetic Type Gold Deposits

Pyrite is an ordinary mineral which appears in different types of deposits and it is an important gold-bearing mineral in gold deposits. Through studying the composition typomorphic characteristics of pyrite, we have achieved some genesis information. However, the study on pyrite composition typomorphism in different genesis gold deposits is rare. The paper studied major and trace elements of pyrite of different genetic deposits by using δFe—δS, δFe/δS—As, (Fe+S)—As and Co—Ni—As plot method and achieved major elements characteristics of different deposits. The results show that each genetic type gold deposit has its typical characteristics. This result are well applicable to genetic studies of pyrite in gold deposits and the distribution characteristics are helpful for studying pyrite in gold deposits

Influence of crude oil cracking on distribution of hydrocarbons in the Earth’s interior (experimental data)

The compositions and phase conditions of water-hydrocarbon fluids in synthetic quartz inclusions were studied by the methods of microthermometry, local IR spectroscopy, and gas-liquid chromatography. Synthetic quartz was grown in near-neutral fluoride, low-alkali bicarbonate, and alkali carbonate solutions with crude oil and its major fractions. The crystals with fluid inclusions were grown under thermal gradient conditions at relatively low temperatures (240–280°C) and pressures (6–45 MPa). After the study, the inclusions of grown crystals were subject to thermal processing in autoclaves at 350–380°C and 80–125 MPa. As a result, the initial water-hydrocarbon inclusions underwent significant changes. Hydrocarbon gases, largely methane and residual solid bitumens, appeared in their composition; the gasoline-kerosene fraction content increased substantially in liquid hydrocarbons (HCs). These changes are caused, first of all, by crude oil cracking, which is manifested already at 330°C and attains its maximum activity at 350–500°C (pressure of saturated vapor and higher). In natural conditions with increase in depths and, thus, the thermobaric parameters, this process is inevitable. According to the obtained experimental data, this very phenomenon and the existence of real thermal and baric gradients in the Earth’s interior provide for the formation of vertical zoning in the distribution of hydrocarbon deposits of different types.

An Empirical Approach to Deposit Mobilization of Commercial Banks in Tamilnadu

Deposit mobilization is an integral part of banking activity. Mobilization of savings through intensive deposit collection has been regarded as the major task of banking in India today. Acceptance of deposits is the primary function of commercial banks. As such, deposit mobilization is one of the basic innovations in current Indian banking activity. Hence, in this paper, an attempt is made to empirically evaluate the trend and growth in deposit mobilization of scheduled commercial banks in Tamil Nadu during the period from 1999-2000 to 2008-2009. Three different types of deposits, namely current deposit, savings deposit and term deposit is considered for the study. The total number of deposits accounts and total amount of deposits mobilized during the years from 1999-2000 to 2008-2009 in all scheduled commercial banks in Tamil Nadu is gathered from RBI bulletin. The collected time series data are subjected descriptive statistics. The Compound Growth Rate (CGR) and Linear Growth Rate (LGR) are calculated using simple regression analysis. From the results of the analysis, it is found that there has been a remarkable growth in mobilization of all kinds of

Stratigraphy of the Younger Dryas Chronozone and paleoenvironmental implications: Central and Southern Great Plains

The Great Plains of the United States was the setting for some of the earliest research in North America into patterns and changes in the character of late Pleistocene environments and their effects on contemporary human populations. Many localities in the region have well-stratified records of terminal Pleistocene and early Holocene human (Paleoindian) activity and past environments. These have proven important in debates over the character of the Younger Dryas Chronozone (YDC; 11,000–10,000 14C BP; 12,900–11,700 cal BP) in the continental interior. This paper reviews the lithostratigraphic record of the YDC on the Central and Southern Great Plains and summarizes paleobiological records (largely isotopic). The goal is to determine if there is any uniformity in the timing, character, direction and/or magnitude of changes in depositional environments or broader geomorphic systems before, during or after the YDC in order to address the question of the character of environments through this time. The stratigraphic records of the late Pleistocene to early Holocene transition, and in particular, the stratigraphic records of the YDC vary through time and space. The data clearly show that a host of geomorphic processes produced the terminal Pleistocene and early Holocene stratigraphic records of the Great Plains. Moreover, the YDC is not necessarily manifest as a distinct lithostratigraphic or biostratigraphic entity in these different types of deposits and soils. The various geomorphic systems of the Great Plains did not behave synchronously in response to any common climate driver. These stratigraphic records reflect local environmental conditions and probably a complex response to the reorganization of mid-latitude climates in the terminal Pleistocene and early Holocene.

Paleomagnetic determination of emplacement temperatures of pyroclastic deposits: an under-utilized tool

Paleomagnetic data from lithic clasts collected from Mt. St. Helens, USA, Volcán Láscar, Chile, Volcán de Colima, Mexico and Vesuvius, Italy have been used to determine the emplacement temperature of pyroclastic deposits at these localities and to highlight the usefulness of the paleomagnetic method for determining emplacement temperatures. At Mt. St. Helens, the temperature of the deposits (T dep ) at three sites from the June 12, 1980 eruption was found to be ≥532°C, ≥509°C, and 510–570°C, respectively. One site emplaced on July 22, 1980 was emplaced at ≥577°C. These new paleomagnetic temperatures are in good agreement with previously published direct temperature measurements and paleomagnetic estimates. Lithic clasts from pyroclastic deposits from the 1993 eruption of Láscar were fully remagnetized above the respective Curie temperatures, which yielded a minimum T dep of 397°C. Samples were also collected from deposits thought to be pyroclastics from the 1913, 2004 and 2005 eruptions of Colima. At Colima, the sampled clasts were emplaced cold. This is consistent with the sampled clasts being from lahar deposits, which are common in the area, and illustrates the usefulness of the paleomagnetic method for distinguishing different types of deposit. T dep of the lower section of the lithic rich pyroclastic flow (LRPF) from the 472 A.D. deposits of Vesuvius was ~280–340°C. This is in agreement with other, recently published paleomagnetic measurements. In contrast, the upper section of the LRPF was emplaced at higher temperatures, with T dep ~520°C. This temperature difference is inferred to be the result of different sources of lithic clasts between the upper and lower sections, with the upper section containing a greater proportion of vent-derived material that was initially hot. Our studies of four historical pyroclastic deposits demonstrates the usefulness of paleomagnetism for emplacement temperature estimation.

Deposition of detonation nanodiamonds by Langmuir–Blodgett technique

Langmuir–Blodgett technique, which classically allows preparing monomolecular films, was here used to deposit a film of detonation nanodiamond particles. We proceeded to the functionalization of the nanodiamond (nD) particles so as to obtain hydrophobic nanodiamonds. Cetyltrimethylammonium chloride (C 19H 42ClN) (CTAC) was used for this purpose in order to form an ionic complex ND–COO −(NH 3) +–R with the functional groups of the nanodiamonds. Compressions with various strengths (10 to 30 mN/m) were performed on the Langmuir–Blodgett device in order to prepare different types of deposits on mica substrates. Atomic Force Microscopy was used to characterize these deposits. It was shown that compressions with low intensity result in discontinuous distributions of the particles on the surface. Conversely, very dense and continuous deposits were observed for higher compression strengths. By optimizing the nD/CTAC ratio in the suspension, a very regular deposit with a monoparticle height was obtained.

Growth and evolution of an emergent tuff cone: Considerations from structural geology, geomorphology and facies analysis of São Roque volcano, São Miguel (Azores)

The syn-eruptive and post-eruptive history of São Roque tuff cone, its geological setting and volcanological features were studied in detail to understand the role played by the different factors that contributed to the morphological evolution of this relatively simple and small volcanic edifice. In addition, attention was also focused on the series of natural changes that affected the tuff cone during the course of the years and that finally led to its structural disassembly. A novel model is proposed to explain this process. The São Roque volcanic centre, located on the island of São Miguel (Azores), consists of two well-consolidated bodies and numerous small islets that formed more than 4700 years ago during the hydromagmatic activity that took place along an intruding dyke, whose NNW–SSE trend is in agreement with the regional tectonic pattern. The eruptive vents probably migrated progressively from SSE to NNW, forming small edifices through the rapid accumulation of sediments during alternating phases of “dry” and “wet” magmatic emissions. Syn-eruptive partial collapses greatly modified the original morphological structure of these edifices, probably allowing sea water to continuously flow into the vents. The complex interaction of these factors controlled the depth of magma fragmentation, producing different types of deposits, in which the ash-lapilli ratio varies considerably. The high-water saturation degree of these deposits caused syn-eruptive and post-eruptive remobilization which resulted in collapses and some small-scale landslides. Post-eruptive, WNW–ESE trending transtensional and extensional tectonic activities operated during the initial dissection of the cone, generating instability. Furthermore, the rapid accumulation of “wet” tephra, and its following consolidation, caused selective collapses that favoured the fragmentation of the deposit and caused the formation of numerous islets separated by radially-arranged channels. Collapses also involved the lava units emplaced in more recent times around the tuff cone, which show that brittle deformation has been significant in the area for a prolonged period.

Physicochemical modeling of the coupled behavior of gold and silver in hydrothermal processes: Gold fineness, Au/Ag ratios and their possible implications

An estimation of gold fineness deposited from aqueous sulphide–chloride solutions in pyritic ore with varying (Au/Ag) ore has been obtained using thermodynamic modeling (at T = 200–500 °C and P = 1000 bar). Silver sulphide with Au–Ag solid solution or Au–Ag solid solution are only stable under conditions of the Py–Po(–Mt) and Hem–Py (–Mt) buffers depending on Au and Ag concentrations in the ore-forming system. The predominant Au and Ag species in aqueous sulphide–chloride solutions depend on temperature, pH and chloride concentration and these solutions can be grouped as follows: Type I: Acid, high chloride ( m HCl > 0.0l, m NaCl = 1 to 5), high temperature (300–500 °C) solutions in which AgCl 2 − and AuCl 2 − are dominant; Type II: Weakly acidic, near-neutral, medium chloride ( m NaCl ≈ 1), moderate to high temperature (200–400 °С) solutions in which AgCl 2 − and AuHS 0 are dominant; Type III: Near-neutral, high chloride ( m NaCl = 1 to 5), high temperature (300–500 °С) solutions in which AgCl 2 − and Au(HS) 2 − are dominant; Type IV: Alkaline, variable chloride ( m NaOH > 0.01, m NaCl = 0 to 5), moderate to high temperature (200–500 °C) solutions in which Au(HS) 2 − and Ag(HS) 2 − are dominant; and Type V: Acid to near-neutral, low chloride ( m NaCl < 1), low to moderate temperature (< 300 °C) solutions in which AuHS 0 and AgHS 0 are dominant. The acid and near-neutral high- and medium chloride solutions (types I–III) are distinguished by high Ag-carrying capacity and low values of (Au/Ag) aq ≈ 10 − 7 to 10 − 2 . The highest Au-carrying capacity and high (Au/Ag) aq ratios (≈ 10 − 3 to 1) are typical of alkaline solutions of any chloride concentrations (type IV) and low chloride solutions of variable acidity (type V). Data on the physicochemical conditions of Au–Ag mineralization and mineralogical–geochemical characteristics of pyritic ores of hydrothermal gold deposits of different types are summarized. Wide ranges of gold fineness and low (Au/Ag) ore ratios of Au–Ag epithermal, Au–Cu-porphyry and Au–Cu-skarn deposits are related to the participation of acid or near-neutral high- or medium chloride ore-forming solutions (types I–III). High fineness gold and high values of (Au/Ag) ore ratio of Au–Te, Au–As, Au–Sb, Au orogenic and Carlin-type deposits are explained by participation of alkaline (type IV) or low chloride (type V) sulphide solutions. Gold fineness and (Au/Ag) ore ratios in the sulphide ores may be characteristics that determine the type of ore solution and its evolution in the process of hydrothermal deposit formation.

Baltijos silūro baseino pržidolio karbonatinės sistemos "rifų" prigimtis

There is a growing interest in different aspects of carbonate reservoirs because of the importance of a number of large and giant carbonate oilfields in the Middle East and the Caspian Sea area. A number of these reservoirs are found in Palaeozoic carbonates. Silurian carbonates in the Silurian Baltic Basin form an excellent target for research because of the availability of numerous cores and outcrops and a limited impact of tectonic deformation in this marginal cratonic basin. This research is focused on Pridol ian carbonates, including shallow to deep basin facies, in the Lithuanian subsurface. In this paper, a new opinion will be presented about the sedimentological nature of the so-called reefs in this basin. The term reef appears often loosely applied to different types of deposits. Although the tectonic synsedimentary setting is undoubtedly important, it is however crucial to determine the exact nature of the reefal deposits because they tend to determine the nature of the carbonate system. In case of real reefs, i. e. bioconstructed deposits with a significant relief, carbonate platforms while otherwise ramps develop. The research shows that Pridolian carbonates lack reefs since the framework-constructing fauna is absent, and probably was absent during most of the Palaeozoic. Contrary to bioherms or reefs, biostromal deposits are formed on a ramp system and appear to be one of the main carbonate-producing parts of the system. The exact impor tance of the different facies belts in carbonate production is difficult to assess. It is crucial to distinguish between the ramp and the platform systems because these two end member systems react differently to diagenesis which ultimately determines the petrophysical properties and thus the reservoir quality.

Ore-magmatic systems and metallogeny of gold and silver in Northeastern Asia

Regional ore-magmatic systems (OMS’s) and metallogenic gold-silver belts in northeastern Asia are considered, with emphasis placed on their relationships owing to the effect of geodynamic settings and underlying and host rock sequences on the localization of gold and silver deposits of different types. Particular types of lithologic assemblages with specific mineralogical and geochemical features are persistent throughout the metallogenic belts, controlled by regional noble-metal OMS’s. Regional OMS’s with one-, two-, and multilevel local OMS’s producing different types of noble-metal mineralization are described. The problem of mineral typomorphism in metallogenic analysis has been first raised. This analysis permits one to recognize indicators of ore formation (a particular genetic type of deposits, their formation and denudation levels), sources of ore-forming fluids, regional specific geochemistry and its relationship with magmatism. Regular presence of platinum in gold-bearing metallogenic zones is shown.