Marble Unit Research Articles

Application of Remote Sensing and Spectroradiometry in Geological Mapping: a case study of Handeni (QDS 148) Block, Eastern Mozambique Belt, Tanzania

This study applies remote sensing (RS) as a geologic mapping aid tool , using Handeni Block of Tanzania as a case study. To achieve the objective of this study, we have utilized various RS processing and image enhancement techniques on multispectral data, including ASTER, Landsat 5, Landsat 8, and Sentinel 2A. The method proved successful whereby both Landsat-5-data with band combination (BC) 7:4:2 and 7:5:4 and band ratio (BR) 5/3:5/1:7/5 and Landsat-8 data with BCs 5:6:7 and 7:6:4 mapped out marble units. Sentinel 2A data (with BC 8:11:3, BRs 12/2:11/2:8/11; 12/4:11/3:11/2 and 12/4:12/2:11/3) together with image enhancement decorrelation stretch on BC 4:3:2 and BC 8:11:3 images succeeded to map other major geologic units. The findings were tested using another approach, an unsupervised classification (K-means algorithm) of Landsat 8 data and unsupervised and supervised classifications by IsoData and minimum distance algorithms, respectively. Similar results were obtained from the image classification whereby Sentinel 2A data produced classified images, which consistently delineate the same lithologies. Geologic structures (lineaments) have been mapped by ASTER DEM data. The result from supervised classification using end-member spectra of the collected representative rock samples also supports the remotely sensed lithologies, demonstrating the usefulness of RS in geologic mapping. The finding of this work have shown that the integration of RS and rock spectral analyses can be used as a robust aiding tool in geologic mapping. The method is more resource efficient than a purely conventional approach.

Mineralogy of the scheelite-bearing ores of Monte Tamara, SW Sardinia: insights for the evolution of a Late Variscan W–Sn skarn system

AbstractSouthwestern Sardinia, Italy, hosts several skarn, W–Sn–Mo greisen and hydrothermal deposits related to a 289±1 Ma Late Variscan granite suite. Among them, the most representative scheelite-bearing skarns belong to the San Pietro and Sinibidraxiu localities, in the Monte Tamara area, Sulcis region. The San Pietro deposit is a typical calc-silicate skarn whereas Sinibidraxiu is a sharply bounded orebody hosted in a marble unit. Optical petrographic observations and compositional data of major and trace elements were obtained for samples from both localities. San Pietro data suggests evolution from an oxidising prograde skarn stage (andradite–diopside, hematite and scheelite), to progressively more reducing conditions from the early retrograde (magnetite–cassiterite) to the late sulfide stage (arsenopyrite, stannite, molybdenite, Bi sulfosalts and Zn–Cu–Pb–Fe sulfides); Sinibidraxiu has diffuse carbonate–quartz intergrowths pseudomorphic over an early mineral assemblage with fibrous habit, followed by abundant ore mineral precipitation under reducing conditions (scheelite, arsenopyrite and Pb–Zn–Cu–Fe sulfides). Geothermometers indicate a comprehensive temperature range of 460–270°C for the sulfide stages of both deposits. The differences between the two deposits might be controlled by the distance from the source intrusion coupled with the different reactivity of the host rocks. The San Pietro mineralogy represents a more proximal skarn, contrasting with more distal mineralogical and chemical features characterising the Sinibidraxiu orebody (lack of Mo–Sn–Bi phases; LREE–MREE–HREE signature of scheelite). This investigation contributes for the first time to the identification of a W–Sn skarn system in SW Sardinia, thereby suggesting the Monte Tamara area and its surroundings as favourable for further exploration.

Ergonomic risk assessment of tasks performed by workers in granite and marble units using ergonomics tool’s REBA

Mining industry, of which the marble, granite and stone market is one such high performing sector. among the various high performing sectors in the Indian economy. Musculoskeletal disorder’s [MSD’s] are a major concern in industries. MSD’s are the predominant factors,leading to injuries and disability in many industries. Adverse working postures of the employees exposed risks levels of injury and that of the hazard. MSD’s risk factors shall be assessed in order to plan and implement ergonomics intervention awareness among the workers so as to minimize work-related health risks in these sectors by identifying potential risks that may lead to injury or musculoskeletal disorders in a marble and granite units. The intent of the current research work is to recognize innumerable MSD’s of the labourer involved in this sector. The procedure was initiated with a workplace observation followed by simple questionnaire among twenty-five operators.The working activities of these workers were recorded from which images were taken for analysis. The assessment shall be organized at the initial stage as well as at later stage to address that the ergonomic intervention has worked out successfully in reducing the possibility of injuries and MSD’s risk factors. The result reflects that more than ninety percent of the employees were suffering from high levels of risk and needs quick change. The researcher proposed ergonomically designed new workstation to reduce injuries & WRMSD’s to an acceptable level with awareness and ergonomic training to workers.

Hydrothermal alteration, lithogeochemical marker units and vectors towards mineralisation at the Svärdsjö Zn-Pb-Cu deposit, Bergslagen, Sweden

ABSTRACT The Svärdsjö Zn-Pb-Cu deposit is situated in the heavily mineralised Bergslagen lithotectonic unit of the Fennoscandian shield, south-central Sweden. Intense hydrothermal alteration followed by a strong overprint by deformation and metamorphism during the Svecokarelian orogeny complicate interpretation of the local geology. Integration of whole-rock lithogeochemical and petrographic methods has allowed the mainly dacitic volcanic host succession and effects of ore-related hydrothermal alteration to be characterised. Mineralisation is hosted by 2–15 m thick, commonly skarn-altered dolomitic marble interbeds. Zones of strong–intense hydrothermal chlorite-sericite alteration envelop the marble units, recording mass gains of Fe and Mg, as well as Na depletion. Minerals such as cordierite, anthophyllite and sillimanite formed in these rocks during regional metamorphism. Mineralisation via sub-seafloor replacement is suggested for the deposit based on alteration zoning and the irregular, stratabound, marble-hosted style of sulphide lenses. It is inferred that mineralisation formed via neutralisation of hot, acidic metalliferous fluids. Geochemically and lithologically distinct units adjacent to the mineralised zones can serve as marker units to aid further exploration in the area. Mass change calculations reveal that Fe and Mg enrichment, as well as Na depletion exhibit detectable changes extending up to 100 m from the mineralised lenses, providing exploration vectors.

An integrated approach towards marble waste management: GIS, SFA, and recycling options.

Marble units generate an enormous amount of non-biodegradable waste during the processing operations and are considered one of the environmentally unfriendly industrial sectors. This sector has become a global nuisance due to its multi-dimensional damaging nature. Therefore, a multidimensional approach is needed to geographically describe the pollution sources, their waste load, collection mechanism, and their proper disposal or reuse. This article highlights an integrated approach to sorting out the multidimensional issues associated with the marble sector. More than 150 marble processing units (MPUs) are scattered in the study area pouring waste into the environment in the form of slurry. The produced waste roots environmental issues both for fauna and flora of the terrestrial and aquatic segments of the environment. A geospatial-based attempt has been made through geographic information system (GIS) for the identification and description of the pollution sources, MPUs, in the study area. The quantitative assessment has been made through substance flow analysis (SFA) by taking raw marble as the input source and marble product as output. Furthermore, material characterization has been carried out to confirm the chemical composition of the slurry waste for its potential use. Results confirmed that a major part (> 90%) of marble powder is calcium carbonate (CaCO3) which has so many potential uses as raw material. The integrated approach of GIS, SFA, and chemical characterization set forth a model that satisfies multi-dimensional queries regarding pollution sources, pollution load, and sustainable solutions to the problem. The output integrated model provides a digital environmental baseline for the monitoring of MPUs, the amount of waste generated by these MPUs, and its potential reuse options. The proposed model can be utilized worldwide as a decision support tool due to its optimum results.

Marble waste site suitability assessment using the GIS-based AHP model

Site suitability with regards to environmental protection, public concerns, and the legitimate prerequisite is a basic issue that has been tended to in this study. By and large, marble waste is being unloaded on accessible open spaces or released in water to the close by waterways in the territory, Mohmand marble zone (Shabqadar), Khyber Pakhtunkhwa, Pakistan. Suitability assessment for marble waste collection and disposal was carried out through the integrated approach of analytical hierarchy process (AHP) and geographic information system (GIS) to limit the ecological dangers, public, and government concerns related to marble waste. The available land use was ordered into three main land use classes followed by six sub-classes including water bodies and agriculture (environmental), settlement and social site (social), and marble units and roads (economic). These sub-classes in the investigation region were organized through pairwise correlation and weighted sum analysis, AHP procedure. The AHP results were interpreted through GIS tools of digitization, buffering, and overlay in ArcMap, ArcGIS. The integrated AHP and GIS outcomes were consolidated to get the optimum results of the study, marble waste collection, and disposal options. It was concluded that priority should be given to water bodies followed by agricultural land while protecting the available land use classes from marble waste hazards. The percent priority values calculated are 32.33%, 30.50%, 12.16%, 10.66%, 8.50%, and 6% for water bodies, agricultural land, settlements, marble processing units, roads, and cultural sites respectively. The sequence of priority of the land use values are waterbodies > agriculture > settlement > marble industries > road > cultural site. The proposed integrated model is helpful in site suitability for waste management by the authorities and decision-makers associated with waste management.

Neoproterozoic to Palaeozoic tectonic deformation history of the western Jiangnan Orogen, South China: Insights from new structural and geochronological data from northern Guangxi

Recognition of deformation events documented in Neoproterozoic sedimentary sequences of the Jiangnan Orogen is critical in understanding the tectonic evolution of South China. In this contribution, we present new field based structural observations, microstructural analysis, and geochronological data for the Sibao and Danzhou groups in the southwestern Jiangnan Orogen of northern Guangxi, South China. Integrating the new information with previously published structural and geochronological data, we have identified three major deformation events. The earliest event generated E–W‐trending high‐angle tight linear and overturned isoclinal folds in the Sibao Group with their fold axial planes dipping to the south. This shortening event occurred in the mid‐Neoproterozoic time (840–800 Ma) and was associated with the orogenic collision between the Yangtze and Cathaysian blocks in South China. The angular unconformity between Sibao and Danzhou groups provides strong evidence for the collision. The second deformation event produced the large‐scale NNE–SSW‐striking ductile shear zones in the region. It also overprinted the pre‐existing E–W‐trending folds, refolded the Sibao Group, and generated the large‐scale NNE–SSW‐trending open folds in the overlying Danzhou Group and the west‐dipping cleavage within both groups. The second event occurred during the early Palaeozoic time (460–410 Ma) as a result of a WNW–ESE‐oriented intracontinental shortening process. The latest deformation event generated slight crenulation cleavage in the Sibao Group, some folds in the marble units of the Danzhou Group, and normal‐sense shearing along the pre‐existing NNE–SSW‐striking shear zones, all of which are the result of a NW–SE‐directed crustal extension during the late Palaeozoic (410–350 Ma) Kwangsian (Caledonian) orogenic collapse.

Ground Water Quality Assessment of Marble Mining Areas in Rajsamand District, Rajasthan, India

The present study represents the impact of marble mining and processing units on the quality of ground water in the Rajasamand district of Rajasthan state. For this work various water sampleswere collected from surrounding areas of the mining hub covering all the tehsil namely- Rajasmand, Amet, Bhim, Deogarh, Khamnor,Kumbhalgarh, and RailmangraofRajasamd district. The sample were analysed for various Physio- chemical parameters like-Electrical Conductivity(EC), pH, Total Hardness (TH), Dissolved Solids-Total (TDS), Sodium (Na+1) Potassium(K+1), Calcium (Ca+2), Magnesium (Mg+2), Chloride (Cl-1), Sulphate (SO4-2), Carbonate (CO3-2 ), Bicarbonate (HCO32), Nitrate(NO3-1) , Fluoride (F), the result of water quality parameters was compared with IS:10500-2012 drinking water specification. The finding of results indicates that the level of the certain parameters like TDS, TH, Ca, Mg, Na, K, Cl, NO3, andF exceed the limits of ground water stipulated by Bureau of Indian Standards (BIS). As per the observations, we must say that it may be possible that one of the egregious sourcesto polluting ground water in the region is marble mining and its allied activities. The present study is based on the sample collected and tested in the laboratory and it is an attempt to determine the physio- chemical characteristics of ground water in the marble mining area of the Rajasamand district in Rajasthan state of India.

Uraniferous Leucogranites in the Rössing Area, Namibia: New Insights from Geologic Mapping and Airborne Hyperspectral Imagery

Abstract This study combines historical exploration data with new mapping, underpinned by airborne hyperspectral imagery, to provide a detailed camp-scale geologic view of the Rössing uranium mine area in the Damara orogen, Namibia. The Neoproterozoic Damaran metasedimentary host rocks to uranium deposits of the Rössing area structurally overlie Paleoproterozoic basement rock. Both units were subjected to polyphase deformation and upper amphibolite to lower granulite facies metamorphism during Pan-African orogenesis. The sequence was voluminously intruded by leucogranites, where younger phases may contain ore-grade uranium as magmatic uraninite and traces of betafite, together with secondary uranium minerals. Early, postdepositional modifications to the Damaran sequence included partial dolomitization of marble units and development of evaporite dissolution and diapiric breccias. Major pre-D3 extensional structures developed in conjunction with recumbent, isoclinal folding and acted to focus the intrusion of early, mostly barren leucogranites generated primarily through anatexis of Damaran metasediments. Syn-D4 leucogranites overprint complex interference fold geometries that resulted from D3 deformation. D4 leucogranites were emplaced under predominantly ductile, transtensional conditions, into NNE-trending zones oriented highly oblique to all preexisting structures. These steeply dipping zones provided the prerequisite conditions for partial melt material to be derived from uraniferous basement lithologies. The concentration of magmatic uranium was promoted where leucogranite melt material interacted with carbonates and sulfide-bearing Damaran metasedimentary units. In the Rössing area these horizons occur at the Khan-Rössing Formation contact zone for the SJ, SK, SH, Z20, and Husab deposits and within and above the Arandis Formation for the Z19 deposit leucogranites.

Lithostratigraphic and structural data from Hardangervidda, southern Norway supporting extended interaction between Avalonia and Baltica

Abstract Lithostratigraphic and structural data from the Early Paleozoic Hardangervidda Group in southern Norway indicate that SW Baltica was affected several hundred kilometres NE of the inferred collision zone with Avalonia (Thor Suture). The first sign of plate interaction was the deposition of a 50–60 m-thick quartz arenite (Holberg Formation) of Floian/Dapingian age in an otherwise mud- and carbonate-dominated shelf. An overlying 5–6 m-thick marble unit of Dapingian–Darriwilian age (‘Orthoceratite Limestone’) marks a change into greenish-grey, calcareous phyllite, locally with beds of impure marble and poorly sorted metasandstone (Solnut Formation). A series of décollement folds (D 2 structures) with axes orientated NW–SE (cross-folds) which superimposed a thin-skinned fold thrust with a NE–SW trend (D 1 structures) are interpreted as having developed during the progressive underthrusting of Baltica underneath Avalonia. Support for this model is seen in detrital zircon populations: with the Holberg and underlying formations having a Baltican signature, in contrast to the overlying Solnut Formation with a peri-Gondwana signature, including a distinct Late Neoproterozoic zircon population. It is further speculated that the c. 471–458 Ma Garborg eclogite and surrounding paragneisses in the Stavanger area are related to the suture zone between Baltica and Avalonia rather than being related to the Iapetus Ocean and Laurentia, as generally thought.

Zn-isotopic evidence for fluid-assisted ore remobilization at the Balmat Zinc Mine, NY

Shear zone-hosted ore bodies at the Balmat, NY, zinc deposit were remobilized at the kilometer scale during amphibolite facies metamorphism ca. 1180 Ma. Despite there being little evidence for interaction of hydrous fluids with ores during deformation, such translocation distances are considered unlikely without the assistance of fluids. Measurements of Zn isotopic composition of sphalerite from six Balmat ore bodies that originated from the same stratigraphic level (Upper Marble unit 6) reveal variation between ore bodies, as well as intra-orebody trends of isotopic lightening down plunge. In general, increasing distance of remobilization correlates with decreasing δ66Zn. The syn-tectonic isotopic fractionation recorded in Balmat sphalerite is interpreted to have resulted from the interaction between the ore and sulfide melts that were fluxed by H2S localized primarily in Upper Marble unit 7 (fetid dolomite). Lighter isotopes of Zn were enriched in the melt, leaving the residual ore enriched in heavier Zn isotopes. These observations support previous petrographic evidence for the presence of anatectic melts at Balmat and help to explain the unusual scale of translocation at Balmat by means of fluid-assisted remobilization during which intergranular melts decreased rock competency.

Water pollution and occupational health hazards caused by the marble industries in district Mardan, Pakistan

Abstract The present study was aimed to assess physico-chemical parameters and heavy metals (HM) concentration in marble industrial effluents, and HM bioaccumulation in the workers’ blood employed in the marble industries in Mardan Industrial Estate (MIE) of district Mardan, Khyber Pakhtunkhwa (KP) province, Pakistan. A total of twelve samples were collected from industrial effluents and seven samples of blood were collected from healthy workers of different marble units on volunteer basis. Water samples were collected for analysis of physico-chemical parameters such as electrical conductivity (EC), pH, turbidity, sodium (Na), potassium (K), calcium, hardness, chloride, magnesium (Mg) and heavy metals, that is Copper (Cu), Manganese (Mn), Zinc (Zn) and Arsenic (As), and compared with the National Environmental Quality Standards (NEQS) of World Health Organization ( WHO, 2010 ). Blood samples from the marble industries workers were collected for the analysis of HM i.e. Cu, Mn, Zn and As bioaccumulation. Our results showed that most of the samples showed higher physico-chemical parameters with respect to the permissible limit set by the NEQS of WHO, 2010. Similarly, HM in water as well as in workers blood also revealed higher values than the permissible limit concentrations set by Occupational Health and Safety Act (OSHA), Occupational Health and Safety Division (OHSD) and Agency for Toxic substances and Disease Registry (ATSDR), USA. Therefore, the major findings of the study suggested that higher level of alteration in the physico-chemical parameters and HM in water and workers’ blood will have great impact on freshwater resources and human health in the study area. Therefore, it is highly recommended that wastewater treatment plant should be constructed in the MIE of district Mardan to treat polluted water discharged from the marble manufacturing units prior entering into freshwater courses in the study area. Moreover, an awareness program should be launched to aware the workers of marble manufacturing units, as well as local community, regarding water pollution and heavy metals bioaccumulation caused by marble production units, and its mitigation to protect themselves and aquatic wildlife from the devastating impacts of water pollution occurring in the study area.

The nexus between entrepreneur skills and successful business: a decompositional analysis

Entrepreneurship, which then began as a concept in 1700s, has now become a buzzword. Specifically, the concept has been practically spread over all sectors of the economy, and across countries and regions; Pakistan is not an exception. Today, although the notion of entrepreneurship is more or less understandable, the measurement is not. Equally true, what impact the entrepreneurship skills has on business success is not widely known, let alone empirically measured. It is for this reason the present study is conducted. The results obtained in this study lead to a number of implications; policy, theoretical and empirical. In relation to policy, marble manufacturing units depend on entrepreneur skills; top among which is the resiliency skill. Second, in reference to theoretical and empirical, the results of this study have contributed to the advancement of theory and understanding of entrepreneurship, as well as provided empirical evidence to support the theory at large.

The leverage of entrepreneur skills and entrepreneur traits to business success: a case study of Pakistan's marble industry

To date, knowledge of the relationship between entrepreneur skills, entrepreneur traits, and business performance is fragmented. Therefore, this study inspects the degree to which there is statistical significance that entrepreneur skills and entrepreneur traits predict the success of marble manufacturing businesses operating in the KPK Province, Pakistan. In order to do this, we used PLS-SEM analysis on data collected from 82 small-scale mineral-based marble manufacturing units in the KPK Province to examine these possible effects. Firstly, we empirically identified that the three dimensions of entrepreneur skills (managerial, resiliency, and strategic) are dimensions of entrepreneur skills in the marble manufacturing sector. The empirical results further support the relationship between entrepreneur skills, entrepreneur traits, and successful marble manufacturing. Secondly, we found that entrepreneur skills have a significant positive effect on the success of marble manufacturing within the KPK Province. It was further found that the effect of entrepreneur traits on the success of marble manufacturing in the KPK Province was marginally significant. Finally, the study develops a theoretical framework based on the collected empirical evidence.

Investigation of the Effects of Marble Material Properties on the Surface Quality

This study aims to investigate the effects of material properties of marble on surface roughness and glossiness. For this purpose, four types of limestones were investigated. Physicomechanical properties of samples were determined through laboratory measurements. Mineralogical and petrographical characterizations were made using thin‐section analysis. X‐ray fluorescence (XRF) semiquantitative method was used for chemical analysis. Six different grinding‐polishing tests for each marble unit were done under fixed operational conditions using the same abrasive series. Relationship between the material properties and the surface quality was investigated. Although the polishing‐grinding tests were conducted under the same operational conditions, different levels of roughness and glossiness were observed on different samples. Data obtained from the study proved that the main cause of this difference is textural and chemical composition variations of the marble specimen. Moreover, statistical evaluations showed that porosity, uniaxial compressive strength, and indirect tensile strength have strong effects on the surface roughness and glossiness of the marble specimen. The presence of an inverse relationship between the glossiness and roughness levels was determined as the result of this study as well.

Utilization of Integrated Geophysical Techniques to Delineate the Extraction of Mining Bench of Ornamental Rocks (Marble)

Low yields in ornamental rock mining remain one of the most important problems in this industry. This fact is usually associated with the presence of anisotropies in the rock, which makes it difficult to extract the blocks. An optimised planning of the exploitation, together with an improved geological understanding of the deposit, could increase these yields. In this work, marble mining in Macael (Spain) was studied to test the capacity of non-destructive geophysical prospecting methods (GPR and ERI) as tools to characterize the geology of the deposit. It is well-known that the ERI method provides a greater penetration depth. By using this technique, it is possible to distinguish the boundaries between the marble and the underlying micaschists, the morphology of the unit to be exploited, and even fracture zones to be identified. Therefore, this technique could be used in the early stages of research, to estimate the reserves of the deposit. The GPR methodology, with a lower penetration depth, is able to offer more detailed information. Specifically, it detects lateral and vertical changes of the facies inside the marble unit, as well as the anisotropies of the rock (fractures or holes). This technique would be suitable for use in a second stage of research. On the one hand, it is very useful for characterization of the texture and fabric of the rock, which allows us to determine in advance its properties, and therefore, the quality for ornamental use. On the other hand, the localization of anisotropy using the GPR technique will make it possible to improve the planning of the rock exploitation in order to increase yields. Both integrated geophysical techniques are effective for assessing the quality of ornamental rock and thus can serve as useful tools in mine planning to improve yields and costs.

A dorozsmai márvány (Tiszai-főegység) kőzettani újravizsgálata: deformáció és fluidum hatása a mikroszerkezet fejlődésére

A márványok petrográfiai vizsgálata napjainkig alárendelt szerepet kapott a hazai földtani szakirodalomban. A márványt felépítő ásványfázisok, valamint azok szemcsemérete és a szemcsehatár jellegének meghatározása (kőzetszövet), illetve a deformációs bélyegek feltárása és értelmezése révén azonban átfogó képet kaphatunk a kőzet metamorf fejlődéséről és deformációtörténetéről, ami független bizonyítékokkal szolgálhat a befoglaló metamorf kőzettest korrelációjához.
 A Békés–Codrui-egységen belül elhelyezkedő, Dorozsma környéki kristályos aljzatban egy maximum néhányszor tíz méter vastagságú, markáns töréses deformációt szenvedett márványzóna található. Tanulmányunkban az e zónát mintázó Dorozsma‒4, ‒7 és ‒54 fúrások által feltárt márványból készült archív vékonycsiszolatok petrográfiai vizsgálatát végeztük el.
 A mikroszkópos vizsgálatok alapján a dorozsmai márvány döntően karbonát + kvarc + Mg-klorit ± talk összetételű, finomszemcsés, heteroblasztos szövetű márványból épül fel. A szemcsehatárok jellemzően szutúráltak, illetve beöblösödők, a deformációs ikerlemezek közül dominánsan a II. és a IV. típus van jelen. A mintákban általánosan jellemzők a kisméretű, kvarccal és karbonáttal kitöltött oldódásos üregek, amelyeket mikrokristályos karbonátból álló szegély övez. Erősen átalakult, mikrokristályos kőzetváltozat szintén megfigyelhető, valamint nagyméretű, szigmoid-alakú karbonátklasztok és rezorbeált, polikristályos, alszemcsés szerkezetű kvarcklasztok is megjelennek a mikrokristályos alapanyagban. Helyenként a nagyméretű karbonátszemcsék deformációs ikerlemezeit apró, kisméretű, zárványmentes karbonátszemcsék helyettesítik, amelyek a nagyméretű szemcsék között is megtalálhatók Mg-klorittal együtt.
 Az archív vékonycsiszolatok petrográfiai vizsgálata alapján kijelenthető, hogy a vizsgált márványt többfázisú deformáció érte. A D1 esemény a szöveti bélyegek alapján nagyobb, 250 ºC-ot meghaladó hőmérsékleten mehetett végbe, amelyet később felülbélyegzett egy kis hőmérsékletű deformációs esemény (D2), amelyhez fluidumhatás társult. E fluidum gyengítő hatása okozhatta a vékonycsiszolati léptékben felismerhető képlékény alakváltozást, valamint a kis hőmérsékletű dinamikus rekrisztallizációra utaló szöveti bélyegeket.

A refined late-Cryogenian – Ediacaran earth history of South China: Phosphorous-rich marbles of the Dabie and Sulu orogens

The late-Cryogenian – Ediacaran geological framework for South China is constructed principally from sedimentary successions preserved in the central and western regions of the Yangtze Block. New stratigraphic and carbonate-carbon isotope data allow us to extend that framework into the exhumed HP-UHP subduction complexes of the eastern Dabie and Sulu orogens that separate the South and North China cratons. Those data show that marble and phosphorous-rich (P-rich) units in those complexes were originally part of an Ediacaran shallow-marine shelf-carbonate platform. The basal pebbly schist (metadiamictite) and lowermost P-rich marble of the Jinping Formation (Haizhou Group) in the Sulu Orogen matches in both facies character and C-isotope profile that of the Marinoan-equivalent glacial-cap carbonate couplet of the Nantuo and Doushantuo formations. The Daxinwu Formation (Susong Group) in the eastern Dabie Orogen contains a marble unit that has, for several hundreds of metres, a strikingly uniform C-isotope profile of low δ13C positive values and is overlain by a P-rich graphitic schist; these features match those of the late Ediacaran to early Cambrian Dengying Formation. These correlations establish that the HP-UHP metasedimentary rocks, many of which were once considered to be Palaeo- to Mesoproterozoic in age, are a Neoproterozoic-age cover sequence of the continental margin of the Yangtze Block. Further, their widespread development limits their utility as indicators of offset across the Tan-Lu fault zone and, instead, favours tectonic models that interpret that feature as a continental-scale tear fault formed during the Mesozoic collision and suturing of the North and South China cratons.

Geochemical Characteristics of Metamorphic Rock-Hosted Gold Deposit At Onzon-Kanbani Area, Central Myanmar

Gold and associated base metal mineralization of Onzon-Kabani area located in the western border of generally N-S trending Mogoke Metamorphic Belt where well-known Sagaing fault is served as a western boundary of this area. In this research area, many artisanal and small-scale gold mines were noted in last three decades. Gold mineralization is hosted in marble and gneiss unit of research area but most common in marble unit. Variety of igneous intrusions are also observed in research area. Mineralizations are observed as fissure filling veins as well as lesser amount of disseminated nature in marble unit. Mineralogically, gold are associated with other base metal such as pyrite, galena, sphalerite, chalcopyrite, marcasite and arsenopyrite. Hydrothermal alteration halos are developed in peripheral of hydrothermal conduits or mineralization veins from proximal to distal such as 1) silicic, 2) sericite-illite, and 3) propylitic alteration. Most of hydrothermal minerals from each altered zones showed that near neutral condition of pH (e.g. adularia, calcite, illite, sericite and chlorite). Alternatively, hydrothermal alteration zones that show with ore minerals such as native gold, electrum, sphalerite, galena, chalcopyrite, arsenopyrite and marcasite which mostly observed in silicic alteration zone. Typical boiling characters of vein textures and fluid inclusion petrography are observed in hydrothermal system of research area. Boiling, cooling and mixing are possiblily responsible for gold deposition in hydrothermal system. In this paper, authors are documented to clarify the type of mineralization based on hydrothermal alterations, ore and gangue mineral assemblages and fluid inclusion study. All of these data can describe and play an important role for both with respect to understanding deposit genesis and in mineral exploration.

Geochemical, isotopic and geochronological characterization of listvenite from the Upper Unit on Tinos, Cyclades, Greece

We describe a largely unknown listvenite deposit from Tinos, Cyclades, Greece and combine field observations with petrographic, bulk-rock geochemical, isotope (Sr, O, C), and Rb–Sr geochronological data. The volumetrically small listvenite occurrences are associated with metabasic phyllites, talc schists, meta-gabbros, ophicalcites and serpentinites of the Upper Unit. Geochemical characteristics (high Mg#, Cr, Ni), as well as preserved relic Cr-spinel and the typical mesh-texture of serpentinized Mg-silicates, document derivation from ultramafic precursors. Judging from field and textural observations it is very likely that carbonation affected serpentinite and not unaltered meta-peridotite. The direct contact or transition zones to ultramafic rocks are not preserved, but serpentinites that escaped carbonation are closely associated. The listvenites occur near a low-angle normal fault that probably focused fluid infiltration and distribution. The carbonation is associated with the influx of CO2-rich, K-bearing fluids that led to the formation of ferroan magnesite, quartz and Cr-bearing white mica (fuchsite), but otherwise the transformation of serpentinized peridotite into listvenite had been a largely isochemical process. The studied rocks do not contain elevated concentrations of precious metals (Au, Pt, Pd). Field relationships suggest that the listvenite-bearing occurrences most likely represent the same tectonostratigraphic level as Upper Unit rocks that had been thermally overprinted in the contact aureole of Miocene granitoids at ca. 15Ma. Accordingly the intrusion depth provides a minimum pressure constraint for the somewhat older carbonation. Pressure estimates for thermally overprinted rocks and the granitoids suggest an intrusion depth of ca. 7–10km that corresponds to a pressure of ca. 2–3kbar. Chlorite thermometry applied to the Tinos listvenites mostly indicates temperatures of ca. 250°C during carbonation. Internal Rb–Sr mineral isochrons (different grain-size fractions of fuchsite and magnesite) yielded apparent ages of ca. 16Ma and ca. 19Ma, respectively, which are interpreted to date carbonation and associated fuchsite formation. The new ages indicate that listvenite formation is considerably younger than the presumed Late Cretaceous or Jurassic protolith age of the ultramafic precursors and also post-dates tectonic juxtaposition of the Upper Unit onto the Lower Unit at ca. 21Ma. Although not the dominant process, a contribution of contact metamorphic decarbonation cannot completely be ruled out. The Sr isotope characteristics of magnesite and whole rocks correspond very well to the seawater curve for the formation age indicated by Rb–Sr dating. Carbonate carbon and oxygen isotopes measured for the listvenites suggest that magnesite formed following the deep circulation of fluids and their interaction with other carbonate rocks (possibly the marble units present on Tinos) including a possible contribution from magmatic CO2. The similarity in δ13C and δ18O between listvenite and some of the ophicalcite occurrences could indicate a common origin from the same circulating fluids, but remains elusive at present. Combined, P–T constraints and Sr isotope data imply infiltration of seawater-dominated fluids to a depth of several kilometers. This conclusion is supported by oxygen and carbon isotope data.