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Marble
Kinds of Marble Selected AbstractsMINERO-PETROGRAPHIC AND GEOCHEMICAL CHARACTERIZATION OF ,GRECO SCRITTO' MARBLE FROM CAP DE GARDE, NEAR HIPPO REGIUS (ANNABA, ALGERIA)*ARCHAEOMETRY, Issue 3 2009F. ANTONELLI This work presents the results of the first mineralogical, petrographical and geochemical characterization of the marble quarried from the Cap de Garde headland, not far from Annaba (Algeria). This site is traditionally held by archaeologists to be the main source of supply of the so-called ,greco scritto' marble, which was much used by the Romans for architectural and decorative,ornamental purposes, locally from the first century bc, and in Rome and central and southern Italy from the late Flavian period until the fourth century ad. The databank relating to the quarried material, created here for the first time, is used to establish the origin of ,greco scritto' found in six important Roman cities of North Africa: Hippo Regius and Cuicul (Djemila), in Algeria; Volubilis, in Morocco; Cyrene, in Libya; and Carthage and Utica in Tunisia. The results of this archaeometric study support the hypothesis (already put forward by authors) that the ,greco scritto'used in the Roman Mediterranean originated from different sites, and suggest the existence of a number of North African quarries, also in the vicinity of Annaba. [source] THE PROPERTIES AND IDENTIFICATION OF MARBLE FROM PROCONNESOS (MARMARA ISLAND, TURKEY): A NEW DATABASE INCLUDING ISOTOPIC, EPR AND PETROGRAPHIC DATA*ARCHAEOMETRY, Issue 5 2008D. ATTANASIO This paper reports an updated and enlarged archaeometric database of Proconnesos marbles with the aim of attaining more reliable inter- and intra-site identification. Quarry and artefact samples (n = 397) from 23 different quarrying areas were characterized using petrographic, isotopic and EPR results. The most distinct property of Proconnesos marbles is their extremely weak EPR intensity, associated with the low concentration of Mn2+impurities. This feature, supported by the contribution of other important isotopic and petrographic variables, forms the basis for the correct identification of Proconnesos marbles. Within the site the distribution of properties is relatively homogeneous; only limited intra-site discrimination is possible. All the experimental results, as well as the quarry samples are made available to other researchers willing to measure additional experimental properties, thus increasing the rate of within the site discrimination. Extensive survey has proved that, although about 10% of the samples exhibit maximum grain size below 1.0 mm, no locations exist where fine grained marbles could be intentionally quarried. The historical aspects of Proconnesos marble quarrying and usage are also discussed. [source] ON THE WHITE AND COLOURED MARBLES OF THE ROMAN TOWN OF CUICUL (DJEMILA, ALGERIA)ARCHAEOMETRY, Issue 4 2010F. ANTONELLI This paper reports the results of an archaeometric study of the local and imported marbles found in the Roman town of Cuicul (now Djemila, Algeria), a research project funded by the Sixth Framework Programme of the European Union. Of the few imported coloured lithotypes that have been found, four are of Greek origin and one was imported from Asia Minor. In addition, two other classical Roman coloured stones found on the site are probably of local North African origin (most likely one from Numidia and one from Algeria). With regard to the grey and white marbles employed in the statuary and architecture, petrographic study in thin section and the ,13C and ,18O isotopic data emphasize the frequent use of the local fine-grained lithotype from Filfila (Skikda) together with imported Greek lithotypes (i.e., Pentelic marble, the dolomitic variety of Thasian marble, and Parian marble from Lakkoi) as well as different varieties of the so-called ,greco scritto', whose provenance in some cases still remains uncertain. In fact, the petrographic and geochemical features of the marbles do not always match those known for the classical ,greco scritto' from the quarry of Cap de Garde, near Annaba (Algeria). [source] SCIENTIFIC CHARACTERIZATION OF THE POHORJE MARBLES, SLOVENIAARCHAEOMETRY, Issue 2 2010S. JARC As a former part of the great Roman Empire, Slovenia has many archaeological sites featuring buildings and objects entirely or partly constructed from marble whose provenance is doubtful. In Slovenia, the most probable source of such marble is the Pohorje Mountains. For the purpose of supporting further provenance studies, these marbles are fully scientifically characterized. The techniques used are petrographic and geochemical analysis, stable isotope ratio analysis and EPR spectroscopy. The results show that the Pohorje marbles are highly heterogeneous in both their isotopic and geochemical parameters as well as grain sizes. The parameters of the different Pohorje marble outcrops are compared between themselves and with the parameters of known ancient quarries in the Mediterranean and Austria. The use of a multi-technique approach with combined parameters allows the best possible discrimination. [source] PROVENANCE OF MARBLES FROM NAXOS BASED ON MICROSTRUCTURAL AND GEOCHEMICAL CHARACTERIZATIONARCHAEOMETRY, Issue 2 2010A. EBERT A detailed quantitative microstructural study coupled with cathodoluminescence and geochemical analyses on marbles from Naxos demonstrates that the analysis of microstructures is the most sensitive method to define the origin of marbles within, and between, different regions. Microstructure examination can only be used as an accurate provenance tool if a correction for the second-phase content is considered. If second phases are not considered, a large spread of different microstructures occurs within sample sites, making a separation between neighbouring outcrops difficult or impossible. Moreover, this study shows that the origin of a marble is defined more precisely if the microstructural observations are coupled with cathodoluminescence data. [source] A NEW METHOD FOR THE DETERMINATION OF THE PROVENANCE OF WHITE MARBLES BY CHEMICAL ANALYSIS OF INCLUSION FLUIDS: THE MARBLES OF THE MAUSOLEUM OF BELEVI/TURKEY*ARCHAEOMETRY, Issue 1 2010W. PROCHASKA A new method is presented in this paper to pinpoint the origin of white marbles using the chemical analysis of fluids occurring as micro-inclusions in calcitic or dolomitic marbles. Beside the conventional methods usually applied for this purpose, the analyses of significant anions and cations in fluids extracted from white marbles were used to characterize different types of marbles. Using this new approach it is possible to distinguish different groups of marbles which cannot be separated isotopically. A case study was performed on the mausoleum of Belevi, close to Ephesus in Turkey, and the quarries in the area of the mausoleum. The marbles used for the architecture of the mausoleum cannot be distinguished isotopically but were split into two groups when using fluid inclusion analysis. The corresponding quarry for the high-quality marble (cella walls, columns etc.) turned out to be the Kentli Çiftli?i quarry, which also supplied the marbles for the classical Artemision. According to the chemical and fluid data it can be shown, however, that neither the adjacent famous antique quarry of Belevi nor the underground mine of Kusini, some 5 km away from the mausoleum, are the sources for the marbles used for the construction or decoration of the mausoleum. [source] ACCESSORY MINERALS AS TRACERS IN THE PROVENANCING OF ARCHAEOLOGICAL MARBLES, USED IN COMBINATION WITH ISOTOPIC AND PETROGRAPHIC DATA,ARCHAEOMETRY, Issue 4 2004S. CAPEDRI Thirty-eight archaeological marbles (Roman and medieval) from Modena and Reggio Emilia (northern Italy) were provenanced using the accessory minerals as tracers and the results were compared with those inferred for the same artefacts using isotope composition and MGS (maximum grain size of calcite grains). The number of inferred possible sources is generally lower when using the mineralogical method, which therefore seems to be suited to marble provenancing. [source] AN EPR AND ISOTOPIC STUDY OF THE MARBLES OF THE TRAJAN's ARCH AT ANCONA: AN EXAMPLE OF ALLEGED HYMETTIAN PROVENANCE,ARCHAEOMETRY, Issue 4 2003D. Attanasio The provenance of 20 marble samples drawn from the Trajan's arch at Ancona, which is supposed to be made of Greek, Hymettian marble, has been established on the basis of the independent use of EPR and isotopic data. The results of the two methods are in good agreement and unequivocally indicate a Proconnesian provenance. Sixteen samples are assigned to this site, whereas two are classified as untypical Proconnesian samples and the remaining two are assigned an unlikely Parian provenance. No indication exists for a possible Hymettian origin of the marbles. A multi-method approach, which employs all of the experimental variables simultaneously, demonstrates that the 18 samples identified as Proconnesian belong to several different quarrying areas within the site. This result is taken as an indication that the Proconnesian quarries were run following a highly organized, semi-industrial production model. The origin of the Hymettian/Proconnesian misunderstanding and the possible misclassification of other Roman monuments in Italy are briefly commented on. [source] Adhesion of Listeria monocytogenes to materials commonly found in domestic kitchensINTERNATIONAL JOURNAL OF FOOD SCIENCE & TECHNOLOGY, Issue 7 2008Pilar Teixeira Summary The aim of this work was to investigate the adhesion of Listeria monocytogenes ATCC 15313 to glass, granite, marble, polypropylene from a bowl (PPb), polypropylene from a cutting board (PPcb) and stainless steel (SS), which are materials commonly used in kitchens. Marble and granite were chosen because they are applied as kitchen bench covers and pavements in many countries and there are no literature reports on their behaviour in terms of microbial adhesion. The effect of surface hydrophobicity and roughness on the adhesion process was also analysed. The results showed that the highest extent of adhesion of L. monocytogenes occurred to stainless steel, followed by glass and in less extent to the other materials studied. However, it was not possible to establish a correlation between surface hydrophobicity or roughness and the extent of adhesion of L. monocytogenes. The adherence of L. monocytogenes should be dependent on other factors, like the presence of exopolymers and surface charge. [source] Magnetic Liquid Marbles: Manipulation of Liquid Droplets Using Highly Hydrophobic Fe3O4 NanoparticlesADVANCED MATERIALS, Issue 6 2010Yan Zhao Magnetic liquid marbles exhibit a remarkable ability to be opened (see image) and closed reversibly under the action of a magnetic field. Liquid can be either extracted from or added to the opened liquid marble simply with a capillary needle. Two opened liquid marbles can also be coalesced into a larger one. The magnetic liquid marbles can be maneuvered two- and three-dimensionally. [source] Cultural Property, Restitution and ValueJOURNAL OF APPLIED PHILOSOPHY, Issue 3 2003Janna Thompson abstract,Demands for restitution of cultural artefacts and relics raise four main issues: 1) how claims to cultural property can be justified; 2) whether and under what conditions demands for restitution of cultural property are valid , especially when they are made long after the artefacts were taken away; 3) whether there are values, aesthetic, scholarly and educational, which can override restitution claims, even when these claims are legitimate; and 4) how these values bear on the question of whether artefacts should be returned to their place of origin. I argue that a proper conception of cultural property emphasises the role that artefacts play in the practices and traditions of a collectivity. On the basis of this conception, some restitution claims can be defended as legitimate. However, many demands for restitution are not justified (including the Greek claim to the Parthenon Marbles). Moreover, a case for restitution can be more or less strong, and other considerations sometimes prevail over rights of cultural property. [source] Discovery of eclogite facies carbonate rocks from the Lindås Nappe, Caledonides, Western NorwayJOURNAL OF METAMORPHIC GEOLOGY, Issue 7 2002T. M. Boundy Abstract Eclogite facies carbonate rocks have been discovered associated with the granulite,eclogite transitional rocks within Bergen Arc system, Caledonian Orogen of western Norway. The local occurrences of marbles and calc-silicates are found subparallel to the mafic eclogite facies shear zones on Holsnøy Island. Marbles contain the assemblage calcite (Ca0.99Sr0.01CO3), calcian strontianite (Ca0.18,0.44Sr0.53,0.84CO3), clinopyroxene (Jd7,32), epidote/allanite (Ps0,33), titanite, garnet (Alm52,56Grs28,33Pyp11,16), barite (Ba0.90,0.99Sr0.01,0.10SO4), celestine (Sr0.67,0.98Ba0.01,0.23Ca0.01,0.11SO4), and one apparently homogeneous grain of intermediate composition (Ba0.49Ca0.01Sr0.50SO4). Adjacent eclogites have clinopyroxene with similar jadeite contents (Jd14,34) and similar garnet (Alm51,60Grs26,36Pyp8,14) compositions. The marbles have high contents of Sr (9500,11000 p.p.m) and Y (115,130 p.p.m). However, low concentrations of some key trace elements (110,160 p.p.m. Ba and <5 p.p.m. Nb) appear to indicate that the marble is not a metamorphosed carbonatite. The 87Sr/86Sr ratios range from 0.7051 to 0.7059. Field and petrological relationships suggest that metasomatic reactions and fluids played a significant role in producing and/or modifying the marbles. The breakdown of scapolite in the granulite into carbonates and sulphates during eclogite facies metamorphism may have contributed to the metasomatic formation of the marbles along shear zones. Fluids involved during subduction are an important catalyst for metamorphism and are recognized to have played a critical role in the localized transformation from granulite to eclogite in the Holsnøy Island area. Thermobarometry indicates 640,690 °C and 18,20 kbar for adjacent eclogites and temperatures of 580,650 °C for the calc-silicates. The marble assemblages are consistent with fluid that is dominantly comprised of H2O (XCO2 < 0.03) under high-pressure conditions. Phase equilibria of the marbles constrain the fO2 of the fluids and imply oxidizing conditions of the deep crustal fluids. At present the source of the fluids remains unresolved. The results provide additional insights into the variable and evolving nature of fluids related to subduction and high-pressure metamorphism. [source] Detecting active methanogenic populations on rice roots using stable isotope probingENVIRONMENTAL MICROBIOLOGY, Issue 3 2005Yahai Lu Summary Methane is formed on rice roots mainly by CO2 reduction. The present study aimed to identify the active methanogenic populations responsible for this process. Soil-free rice roots were incubated anaerobically under an atmosphere of H2/13CO2 or N2/13CO2 with phosphate or carbonate (marble) as buffer medium. Nucleic acids were extracted and fractionated by caesium trifluoroacetate equilibrium density gradient centrifugation after 16-day incubation. Community analyses were performed for gradient fractions using terminal restriction fragment polymorphism analysis (T-RFLP) and sequencing of the 16S rRNA genes. In addition, rRNA was extracted and analysed at different time points to trace the community change during the 16-day incubation. The Methanosarcinaceae and the yet-uncultured archaeal lineage Rice Cluster-I (RC-I) were predominant in the root incubations when carbonate buffer and N2 headspace were used. The analysis of [13C]DNA showed that the relative 16S rRNA gene abundance of RC-I increased whereas that of the Methanosarcinaceae decreased with increasing DNA buoyant density, indicating that members of RC-I were more active than the Methanosarcinaceae. However, an unexpected finding was that RC-I was suppressed in the presence of high H2 concentrations (80%, v/v), which during the early incubation period caused a lower CH4 production compared with that with N2 in the headspace. Eventually, however, CH4 production increased, probably because of the activity of Methanosarcinaceae, which became prevalent. Phosphate buffer appeared to inhibit the activity of the Methanosarcinaceae, resulting in lower CH4 production as compared with carbonate buffer. Under these conditions, Methanobacteriaceae were the prevalent methanogens. Our study suggests that the active methanogenic populations on rice roots change in correspondence to the presence of H2 (80%, v/v) and the type of buffer used in the system. [source] Magnetic Liquid Marbles: Manipulation of Liquid Droplets Using Highly Hydrophobic Fe3O4 NanoparticlesADVANCED MATERIALS, Issue 6 2010Yan Zhao Magnetic liquid marbles exhibit a remarkable ability to be opened (see image) and closed reversibly under the action of a magnetic field. Liquid can be either extracted from or added to the opened liquid marble simply with a capillary needle. Two opened liquid marbles can also be coalesced into a larger one. The magnetic liquid marbles can be maneuvered two- and three-dimensionally. [source] Inelastic constitutive properties and shear localization in Tennessee marbleINTERNATIONAL JOURNAL FOR NUMERICAL AND ANALYTICAL METHODS IN GEOMECHANICS, Issue 2 2001D. J. Holcomb Abstract The inelastic response of Tennessee marble is modelled by an elastic plastic constitutive relation that includes pressure dependence of yield, strain-softening and inelastic volume strain (dilatancy). Data from 12 axisymmetric compression tests at confining pressures from 0 to 100 MPa are used to determine the dependence of the yield function and plastic potential, which are different, on the first and second stress invariants and the accumulated inelastic shear strain. Because the data requires that the strain at peak stress depends on the mean stress, the locus of peak stresses is neither a yield surface nor a failure envelope, as is often assumed. Based on the constitutive model and Rudnicki and Rice criterion, localization is not predicted to occur in axisymmetric compression although faulting is observed in the tests. The discrepancy is likely due to the overly stiff response of a smooth yield surface model to abrupt changes in the pattern of straining. The constitutive model determined from the axisymmetric compression data describes well the variation of the in-plane stress observed in a plane strain experiment. The out-of-plane stress is not modelled well, apparently because the inelastic normal strain in this direction is overpredicted. In plane strain, localization is predicted to occur close to peak stress, in good agreement with the experiment. Observation of localization on the rising portion of the stress,strain curve in plane strain does not, however, indicate prepeak localization. Because of the rapid increase of mean stress in plane strain, the stress,strain curve can be rising while the shear stress versus shear strain curve at constant mean stress is falling (negative hardening modulus). Copyright © 2001 John Wiley & Sons, Ltd. [source] Adhesion of Listeria monocytogenes to materials commonly found in domestic kitchensINTERNATIONAL JOURNAL OF FOOD SCIENCE & TECHNOLOGY, Issue 7 2008Pilar Teixeira Summary The aim of this work was to investigate the adhesion of Listeria monocytogenes ATCC 15313 to glass, granite, marble, polypropylene from a bowl (PPb), polypropylene from a cutting board (PPcb) and stainless steel (SS), which are materials commonly used in kitchens. Marble and granite were chosen because they are applied as kitchen bench covers and pavements in many countries and there are no literature reports on their behaviour in terms of microbial adhesion. The effect of surface hydrophobicity and roughness on the adhesion process was also analysed. The results showed that the highest extent of adhesion of L. monocytogenes occurred to stainless steel, followed by glass and in less extent to the other materials studied. However, it was not possible to establish a correlation between surface hydrophobicity or roughness and the extent of adhesion of L. monocytogenes. The adherence of L. monocytogenes should be dependent on other factors, like the presence of exopolymers and surface charge. [source] Overview of the geology, petrology and tectonic framework of the high-pressure,ultrahigh-pressure metamorphic belt of the Kokchetav Massif, KazakhstanISLAND ARC, Issue 3 2000S. Maruyama Abstract High- to ultrahigh-pressure metamorphic (HP,UHPM) rocks crop out over 150 km along an east,west axis in the Kokchetav Massif of northern Kazakhstan. They are disposed within the Massif as a 2 km thick, subhorizontal pile of sheet-like nappes, predominantly composed of interlayered pelitic and psammitic schists and gneisses, amphibolite and orthogneiss, with discontinuous boudins and lenses of eclogite, dolomitic marble, whiteschist and garnet pyroxenite. On the basis of predominating lithologies, we subdivided the nappe group into four north-dipping, fault-bounded orogen-parallel units (I,IV, from base to top). Constituent metabasic rocks exhibit a systematic progression of metamorphic grades, from high-pressure amphibolite through quartz,eclogite and coesite,eclogite to diamond,eclogite facies. Coesite, diamond and other mineral inclusions within zircon offer the best means by which to clarify the regional extent of UHPM, as they are effectively sequestered from the effects of fluids during retrogression. Inclusion distribution and conventional geothermobarometric determinations demonstrate that the highest grade metamorphic rocks (Unit II: T = 780,1000°C, P = 37,60 kbar) are restricted to a medial position within the nappe group, and metamorphic grade decreases towards both the top (Unit III: T = 730,750°C, P = 11,14 kbar; Unit IV: T = 530°C, P = 7.5,9 kbar) and bottom (Unit I: T = 570,680°C; P = 7,13.5 kbar). Metamorphic zonal boundaries and internal structural fabrics are subhorizontal, and the latter exhibit opposing senses of shear at the bottom (top-to-the-north) and top (top-to-the-south) of the pile. The orogen-scale architecture of the massif is sandwich-like, with the HP,UHPM nappe group juxtaposed across large-scale subhorizontal faults, against underlying low P,T metapelites (Daulet Suite) at the base, and overlying feebly metamorphosed clastic and carbonate rocks (Unit V). The available structural and petrologic data strongly suggest that the HP,UHPM rocks were extruded as a sequence of thin sheets, from a root zone in the south toward the foreland in the north, and juxtaposed into the adjacent lower-grade units at shallow crustal levels of around 10 km. The nappe pile suffered considerable differential internal displacements, as the 2 km thick sequence contains rocks exhumed from depths of up to 200 km in the core, and around 30,40 km at the margins. Consequently, wedge extrusion, perhaps triggered by slab-breakoff, is the most likely tectonic mechanism to exhume the Kokchetav HP,UHPM rocks. [source] Microfabric characteristics and rheological significance of ultra-high-pressure metamorphosed jadeite-quartzite and eclogite from Shuanghe, Dabie Mountains, ChinaJOURNAL OF METAMORPHIC GEOLOGY, Issue 2 2010L. WANG Abstract Quantitative analysis of the structural evolution of jadeite-quartzite, a rare ultra-high pressure (UHP) rock type from the Dabie Mountains of eastern China, sheds light on the formation and evolution of UHP orogenic belts worldwide. Geological mapping of the Shuanghe area, where jadeite-quartzites crop out, was carried out to determine the spatial relationships between different UHP rocks within this orogen. The deformation mechanisms of jadeite-quartzite, geodynamical parameters (stress, strain, strain rate), and microstructure including lattice preferred orientation (LPO) were determined from six jadeite-quartzite samples from the Shuanghe area. LPOs of clinopyroxene (jadeite and omphacite), garnet, rutile and quartz from these jadeite-quartzite samples are compared with those of three eclogites preserving different degrees of deformation from the Shuanghe area. Microstructural LPOs of jadeite, omphacite, garnet, rutile and quartz were determined using electron backscattered diffraction (EBSD) analysis. Quartz fabrics were largely recrystallized during late, low-grade stages of deformation, whereas garnet shows no strong LPO patterns. Rutile fabrics show a weak LS fabric along [001]. Jadeite and omphacite show the strongest eclogite facies LPO patterns, suggesting that they may provide important information about mantle deformation patterns and control the rheology of deeply subducted continental crust. Microstructural data show that the jadeite LPO patterns are similar to those of omphacite and vary between L- and S-types, which correlate with prolate and oblate grain shape fabrics (SPO); quartz LPOs are monoclinic. Microstructural analysis using TEM shows that the dominant slip systems of jadeite in one sample are (100)[001], (110)[001] and (1 1 0)1/2[110], while in another sample, no dislocations are observed. Abundant dislocations in quartz were accommodated by the dominant slip system (0001)[110], indicating basal glide and represents regional shearing during the exhumation process. This suggests that dislocation creep is the dominant fundamental deformation mechanism in jadeite under UHP conditions. The protoliths of jadeite-quartzite, metasedimentary rocks from the northern passive continental margin of the Yangtze craton, experienced the same deep subduction and were deformed under similar rheological conditions as other UHP eclogite, marble and paragneiss. Experimental UHP deformation of quartzo-feldspathic gneiss with a chemical composition similar to the bulk continental crust has shown that the formation of a jadeite,stishovite rock is associated with a density increase of the host rock similar to the eclogite conversion from basaltic protoliths. The resulting rock can be denser than the surrounding mantle pyrolite up to depths of 660 km (24 GPa). Thus, processes of deep continental subduction may be better-understood through understanding the rheology and mechanical behaviour of jadeite. Jadeite-quartzites such as those from the Shuanghe may be exhumed remnants of deeply-subducted slabs of continental crust, other parts of which subducted past the ,depth of no return', and remain in the deep mantle. [source] Phlogopite and quartz lamellae in diamond-bearing diopside from marbles of the Kokchetav massif, Kazakhstan: exsolution or replacement reaction?JOURNAL OF METAMORPHIC GEOLOGY, Issue 9 2009L. F. DOBRZHINETSKAYA Abstract Exsolution lamellae of pyroxene in garnet (grt), coesite in titanite and omphacite from UHPM terranes are widely accepted as products of decompression. However, interpretation of oriented lamellae of phyllosilicates, framework silicates and oxides as a product of decompression of pyroxene is very often under debate. Results are presented here of FIB-TEM, FEG-EMP and synchrotron-assisted infrared (IR) spectroscopy studies of phlogopite (Phlog) and phlogopite + quartz (Qtz) lamellae in diamond-bearing clinopyroxene (Cpx) from ultra-high pressure (UHP) marble. These techniques allowed collection of three-dimensional information from the grain boundaries of both the single (phlogopite), two-phase lamellae (phlogopite + quartz), and fluid inclusions inside of diamond included in K-rich Cpx and understanding their relationships and mechanisms of formation. The Cpx grains contain in their cores lamellae-I, which are represented by topotactically oriented extremely thin lamellae of phlogopite (that generally are two units cell wide but locally can be seen to be somewhat broader) and microdiamond. The core composition is: (Ca0.94K0.04Na0.02) (Al0.06Fe0.08Mg0.88) (Si1.98Al0.02)O6.00. Fluid inclusions rich in K and Si are recognized in the core of the Cpx, having no visible connections to the lamellae-I. Lamellar-II inclusions consist of micron-size single laths of phlogopite and lens-like quartz or slightly elongated phlogopite + quartz intergrowths; all are situated in the rim zone of the Cpx. The composition of the rim is (Ca0.95Fe0.03Na0.02) (Al0.05Fe0.05Mg0.90)Si2O6, and the rim contains more Ca, Mg then the core, with no K there. Such chemical tests support our microstructural observations and conclusion that the phlogopite lamellae-I are exsolved from the K-rich Cpx-precursor during decompression. It is assumed that Cpx-precursor was also enriched in H2O, because diamond included in the core of this Cpx contains fluid inclusions. The synchrotron IR spectra of such diamond record the presence of OH, stretching and H2O bending motion regions. Lamellar-II inclusions are interpreted as forming partly because of modification of the lamellae-I in the presence of fluid enriched in K, Fe and Si during deformation of the host diopside; the latter is probably related to the shallower stage of exhumation of the UHP marble. This study emphasizes that in each case to understand the mechanism of lamellar inclusion formation more detailed studies are needed combining both compositional, structural and three-dimensional textural features of lamellar inclusions and their host. [source] Late Cretaceous blueschist facies metamorphism in southern Thrace (Turkey) and its geodynamic implicationsJOURNAL OF METAMORPHIC GEOLOGY, Issue 9 2008G. TOPUZ Abstract A blueschist facies tectonic sliver, 9 km long and 1 km wide, crops out within the Miocene clastic rocks bounded by the strands of the North Anatolian Fault zone in southern Thrace, NW Turkey. Two types of blueschist facies rock assemblages occur in the sliver: (i) A serpentinite body with numerous dykes of incipient blueschist facies metadiabase (ii) a well-foliated and thoroughly recrystallized rock assemblage consisting of blueschist, marble and metachert. Both are partially enveloped by an Upper Eocene wildflysch, which includes olistoliths of serpentinite,metadiabase, Upper Cretaceous and Palaeogene pelagic limestone, Upper Eocene reefal limestone, radiolarian chert, quartzite and minor greenschist. Field relations in combination with the bore core data suggest that the tectonic sliver forms a positive flower structure within the Miocene clastic rocks in a transpressional strike,slip setting, and represents an uplifted part of the pre-Eocene basement. The blueschists are represented by lawsonite,glaucophane-bearing assemblages equilibrated at 270,310 °C and ,0.8 GPa. The metadiabase dykes in the serpentinite, on the other hand, are represented by pumpellyite,glaucophane,lawsonite-assemblages that most probably equilibrated below 290 °C and at 0.75 GPa. One metadiabase olistolith in the Upper Eocene flysch sequence contains the mineral assemblage epidote + pumpellyite + glaucophane, recording P,T conditions of 290,350 °C and 0.65,0.78 GPa, indicative of slightly lower depths and different thermal setting. Timing of the blueschist facies metamorphism is constrained to c. 86 Ma (Coniacian/Santonian) by Rb,Sr phengite,whole rock and incremental 40Ar,39Ar phengite dating on blueschists. The activity of the strike,slip fault post-dates the blueschist facies metamorphism and exhumation, and is only responsible for the present outcrop pattern and post-Miocene exhumation (,2 km). The high- P/T metamorphic rocks of southern Thrace and the Biga Peninsula are located to the southeast of the Circum Rhodope Belt and indicate Late Cretaceous subduction and accretion under the northern continent, i.e. the Rhodope Massif, enveloped by the Circum Rhodope Belt. The Late Cretaceous is therefore a time of continued accretionary growth of this continental domain. [source] Contrasting metamorphic histories of lenses of high-pressure rocks and host migmatites with a flat orogenic fabric (Bohemian Massif, Czech Republic): a result of tectonic mixing within horizontal crustal flow?JOURNAL OF METAMORPHIC GEOLOGY, Issue 6 2008TÍPSKÁ Abstract Migmatites with sub-horizontal fabrics at the eastern margin of the Variscan orogenic root in the Bohemian Massif host lenses of eclogite, kyanite-K-feldspar granulite and marble within a matrix of migmatitic paragneiss and amphibolite. Petrological study and pseudosection modelling have been used to establish whether the whole area experienced terrane-wide exhumation of lower orogenic crust, or whether smaller portions of higher-pressure lower crust were combined with a lower-pressure matrix. Kyanite-K-feldspar granulite shows peak conditions of 16.5 kbar and 850 °C with no clear indications of prograde path, whereas in the eclogite the prograde path indicates burial from 10 kbar and 700 °C to a peak of 18 kbar and 800 °C. Two contrasting prograde paths are identified within the host migmatitic paragneiss. The first path is inferred from the presence of staurolite and kyanite inclusions in garnet that contains preserved prograde zoning that indicates burial with simultaneous heating to 11 kbar and 800 °C. The second path is inferred from garnet overgrowths of a flat foliation defined by sillimanite and biotite. Garnet growth in such an assemblage is possible only if the sample is heated at 7,8 kbar to around 700,840 °C. Decompression is associated with strong structural reworking in the flat fabric that involves growth of sillimanite in paragneiss and kyanite-K-feldspar granulite at 7,10 kbar and 750,850 °C. The contrasting prograde metamorphic histories indicate that kilometre-scale portions of high-pressure lower orogenic crust were exhumed to middle crustal levels, dismembered and mixed with a middle crustal migmatite matrix, with the simultaneous development of a flat foliation. The contrasting P,T paths with different pressure peaks show that tectonic models explaining high-pressure boudins in such a fabric cannot be the result of heterogeneous retrogression during ductile rebound of the whole orogenic root. The P,T paths are compatible with a model of heterogeneous vertical extrusion of lower crust into middle crust, followed by sub-horizontal flow. [source] Petrogenesis of lawsonite and epidote eclogite and blueschist, Sivrihisar Massif, TurkeyJOURNAL OF METAMORPHIC GEOLOGY, Issue 9 2006P. B. DAVIS Abstract The Sivrihisar Massif, Turkey, is comprised of blueschist and eclogite facies metasedimentary and metabasaltic rocks. Abundant metre- to centimetre-scale eclogite pods occur in blueschist facies metabasalt, marble and quartz-rich rocks. Sivrihisar eclogite contains omphacite + garnet + phengite + rutile ± glaucophane ± quartz + lawsonite and/or epidote. Blueschists contain sodic amphibole + garnet + phengite + lawsonite and/or epidote ± omphacite ± quartz. Sivrihisar eclogite and blueschist have similar bulk composition, equivalent to NMORB, but record different P,T conditions: ,26 kbar, 500 °C (lawsonite eclogite); 18 kbar, 600 °C (epidote eclogite); 12 kbar, 380 °C (lawsonite blueschist); and 15,16 kbar, 480,500 °C (lawsonite-epidote blueschist). Pressures for the Sivrihisar lawsonite eclogite are among the highest reported for this rock type, which is rarely exposed at the Earth's surface. The distribution and textures of lawsonite ± epidote define P,T conditions and paths. For example, in some lawsonite-bearing rocks, epidote inclusions in garnet and partial replacement of matrix epidote by lawsonite suggest an anticlockwise P,T path. Other rocks contain no epidote as inclusions or as a matrix phase, and were metamorphosed entirely within the lawsonite stability field. Results of the P,T study and mapping of the distribution of blueschists and eclogites in the massif suggest that rocks recording different maximum P,T conditions were tectonically juxtaposed as kilometre-scale slices and associated high- P pods, although all shared the same exhumation path from ,9,11 kbar, 300,400 °C. Within the tectonic slices, alternating millimetre,centimetre-scale layers of eclogite and blueschist formed together at the same P,T conditions but represent different extents of prograde reaction controlled by strain partitioning or local variations in fO2 or other chemical factors. [source] Reaction progress related to indentation structures at glaucophane/glaucophane contacts in an impure marble from Syros, GreeceJOURNAL OF METAMORPHIC GEOLOGY, Issue 8 2006A. OKAMOTO Abstract Microstructures of brittle mineral grains embedded in a ductile matrix provide information on the influence of stress concentration on reaction progress during metamorphism. Under non-hydrostatic conditions, contrasts of mechanical properties between minerals possibly cause stress concentrations at specific grain boundaries, which may result in a localization of subsequent reactions. In an impure marble from Syros, Greece, glaucophane grains occurring in a calcite matrix commonly impinge on other glaucophane grains to form concavo-convex boundary contacts. The geometrical relationship between grain boundary and growth zoning within glaucophane grains indicates that indentation and dissolution occurred preferentially at the glaucophane/glaucophane contacts in response to compression normal to the foliation. In contrast, idioblastic surfaces of glaucophane were preserved at glaucophane/calcite boundaries, indicating that stress concentrated at glaucophane/glaucophane contacts. The retrograde minerals (winchite, albite and biotite) that were formed by consuming glaucophane are observed not only at the extensive site, but also at the ,compressive' site where indentation occurred. The precipitation of retrograde minerals at the extensive sites was accompanied by glaucophane dissolution at the indentation stage. In contrast, the formation of retrograde minerals at the ,compressive' site indicates that retrograde replacement preferentially proceeded at the indented sites even after stress relaxation. Such a localization of the replacement suggests that the formation of damaged zones around glaucophane/glaucophane contacts induced by stress concentration would have provided the preferential sites for glaucophane breakdown at the later stage. [source] SHRIMP U-Pb zircon dating from Sulu-Dabie dolomitic marble, eastern China: constraints on prograde, ultrahigh-pressure and retrograde metamorphic agesJOURNAL OF METAMORPHIC GEOLOGY, Issue 7 2006F. L. LIU Abstract Laser Raman spectroscopy and cathodoluminescence (CL) images show that zircon from Sulu-Dabie dolomitic marbles is characterized by distinctive domains of inherited (detrital), prograde, ultrahigh-pressure (UHP) and retrograde metamorphic growths. The inherited zircon domains are dark-luminescent in CL images and contain mineral inclusions of Qtz + Cal + Ap. The prograde metamorphic domains are white-luminescent in CL images and preserve a quartz eclogite facies assemblage of Qtz + Dol + Grt + Omp + Phe + Ap, formed at 542,693 °C and 1.8,2.1 GPa. In contrast, the UHP metamorphic domains are grey-luminescent in CL images, retain the UHP assemblage of Coe + Grt + Omp + Arg + Mgs + Ap, and record UHP conditions of 739,866 °C and >5.5 GPa. The outermost retrograde rims have dark-luminescent CL images, and contain low- P minerals such as calcite, related to the regional amphibolite facies retrogression. Laser ablation ICP-MS trace-element data show striking difference between the inherited cores of mostly magmatic origin and zircon domains grown in response to prograde, UHP and retrograde metamorphism. SHRIMP U-Pb dating on these zoned zircon identified four discrete 206Pb/238U age groups: 1823,503 Ma is recorded in the inherited (detrital) zircon derived from various Proterozoic protoliths, the prograde domains record the quartz eclogite facies metamorphism at 254,239 Ma, the UHP growth domains occurred at 238,230 Ma, and the late amphibolite facies retrogressive overprint in the outermost rims was restricted to 218,206 Ma. Thus, Proterozoic continental materials of the Yangtze craton were subducted to 55,60 km depth during the Early Triassic and recrystallized at quartz eclogite facies conditions. Then these metamorphic rocks were further subducted to depths of 165,175 km in the Middle Triassic and experienced UHP metamorphism, and finally these UHP metamorphic rocks were exhumed to mid-crustal levels (about 30 km) in the Late Triassic and overprinted by regional amphibolite facies metamorphism. The subduction and exhumation rates deduced from the SHRIMP data and metamorphic P,T conditions are 9,10 km Myr,1 and 6.4 km Myr,1, respectively, and these rapid subduction,exhumation rates may explain the obtained P,T,t path. Such a fast exhumation suggests that Sulu-Dabie UHP rocks that returned towards crustal depths were driven by buoyant forces, caused as a consequence of slab breakoff at mantle depth. [source] Calcite,graphite isotope thermometry in amphibolite facies marble, Bancroft, OntarioJOURNAL OF METAMORPHIC GEOLOGY, Issue 9 2005S. R. DUNN Abstract This study presents calcite,graphite carbon isotope fractionations for 32 samples from marble in the northern Elzevir terrane of the Central Metasedimentary Belt, Grenville Province, southern Ontario, Canada. These results are compared with temperatures calculated by calcite,dolomite thermometry (15 samples), garnet,biotite thermometry (four samples) and garnet,hornblende thermometry (three samples). ,cal-gr values vary regularly across the area from >6.5, in the south to 4.0, in the north, which corresponds to temperatures of 525 °C in the south to 650 °C in the north. Previous empirical calibration of the calcite,graphite thermometer agrees very well with calcite,dolomite, garnet,biotite and garnet,hornblende thermometry, whereas, theoretical calibrations compare less well with the independent thermometry. Isograds in marble based on the reactions rutile + calcite + quartz =titanite and tremolite + calcite + quartz = diopside, span temperatures of 525,600 °C and are consistent with calculated temperature,X(CO2) relations. Results of this study compare favourably with large-scale regional isotherms, however, local variation is greater than that revealed by large-scale sampling strategies. It remains unclear whether the temperature,,cal-gr relationship observed in natural materials below 650 °C represents equilibrium fractionations or not, but the regularity and consistency apparent in this study demonstrate its utility for thermometry in amphibolite facies marble. [source] Two stage growth of microdiamond in UHP dolomite marble from Kokchetav Massif, KazakhstanJOURNAL OF METAMORPHIC GEOLOGY, Issue 6 2003H. Ishida Abstract The abundance and morphology of microdiamond in dolomite marble from Kumdy-kol in the Kokchetav Massif, are unusual; a previous study estimated the maximum content of diamonds in dolomite marble to be about 2700 carat ton,1. Microdiamond is included primarily in garnet, and occasionally in diopside and phlogopite pseudomorphs after garnet. They are classified into three types on the basis of their morphology: (1) S-type: star-shaped diamond consisting of translucent cores and transparent subhedral to euhedral very fine-grained outer parts; (2) R-type: translucent crystals with rugged surfaces; and (3) T-type: transparent, very fine-grained crystals. The S-type is the most abundant. Micro-Laue diffraction using a 1.6-µm X-ray beam-size demonstrated that the cores of the star-shaped microdiamond represent single crystals. In contrast, the most fine-grained outer parts usually have different orientations compared to the core. Laser,Raman studies indicate that the FWHM (Full Width at Half Maximum) of the Raman band of the core of the S-type diamond is slightly larger than that for the outer parts. Differences in morphology, crystal orientations, and in the FWHM of the Raman band between the core and the fine-grained outer-parts of S-type microdiamond suggest that the star-shaped microdiamond was formed discontinuously in two distinct stages. [source] Discovery of eclogite facies carbonate rocks from the Lindås Nappe, Caledonides, Western NorwayJOURNAL OF METAMORPHIC GEOLOGY, Issue 7 2002T. M. Boundy Abstract Eclogite facies carbonate rocks have been discovered associated with the granulite,eclogite transitional rocks within Bergen Arc system, Caledonian Orogen of western Norway. The local occurrences of marbles and calc-silicates are found subparallel to the mafic eclogite facies shear zones on Holsnøy Island. Marbles contain the assemblage calcite (Ca0.99Sr0.01CO3), calcian strontianite (Ca0.18,0.44Sr0.53,0.84CO3), clinopyroxene (Jd7,32), epidote/allanite (Ps0,33), titanite, garnet (Alm52,56Grs28,33Pyp11,16), barite (Ba0.90,0.99Sr0.01,0.10SO4), celestine (Sr0.67,0.98Ba0.01,0.23Ca0.01,0.11SO4), and one apparently homogeneous grain of intermediate composition (Ba0.49Ca0.01Sr0.50SO4). Adjacent eclogites have clinopyroxene with similar jadeite contents (Jd14,34) and similar garnet (Alm51,60Grs26,36Pyp8,14) compositions. The marbles have high contents of Sr (9500,11000 p.p.m) and Y (115,130 p.p.m). However, low concentrations of some key trace elements (110,160 p.p.m. Ba and <5 p.p.m. Nb) appear to indicate that the marble is not a metamorphosed carbonatite. The 87Sr/86Sr ratios range from 0.7051 to 0.7059. Field and petrological relationships suggest that metasomatic reactions and fluids played a significant role in producing and/or modifying the marbles. The breakdown of scapolite in the granulite into carbonates and sulphates during eclogite facies metamorphism may have contributed to the metasomatic formation of the marbles along shear zones. Fluids involved during subduction are an important catalyst for metamorphism and are recognized to have played a critical role in the localized transformation from granulite to eclogite in the Holsnøy Island area. Thermobarometry indicates 640,690 °C and 18,20 kbar for adjacent eclogites and temperatures of 580,650 °C for the calc-silicates. The marble assemblages are consistent with fluid that is dominantly comprised of H2O (XCO2 < 0.03) under high-pressure conditions. Phase equilibria of the marbles constrain the fO2 of the fluids and imply oxidizing conditions of the deep crustal fluids. At present the source of the fluids remains unresolved. The results provide additional insights into the variable and evolving nature of fluids related to subduction and high-pressure metamorphism. [source] Neoproterozoic high-pressure/low-temperature metamorphic rocks in the Avalon terrane, southern New Brunswick, CanadaJOURNAL OF METAMORPHIC GEOLOGY, Issue 5 2001C. E. White Abstract High -P/low -T metamorphic rocks of the Hammondvale metamorphic suite (HMS) are exposed in an area of 10 km2 on the NW margin of the Caledonian (Avalon) terrane in southern New Brunswick, Canada. The HMS is in faulted contact on the SE with c. 560,550 Ma volcanic and sedimentary rocks and co-magmatic plutonic units of the Caledonian terrane. The HMS consists of albite- and garnet-porphyroblastic mica schist, with minor marble, calc-silicate rocks and quartzite. Pressure and temperature estimates from metamorphic assemblages in the mica schist and calc-silicate rocks using TWQ indicate that peak pressure conditions were 12.4 kbar at 430 °C. Peak temperature conditions were 580 °C at 9.0 kbar. 40Ar/39Ar muscovite ages from three samples range up to 618,615 Ma, a minimum age for high -P/low- T metamorphism in this unit. These ages indicate that the HMS is related to the c. 625,600 Ma subduction-generated volcanic and plutonic units exposed to the SE in the Caledonian terrane. The ages are also similar to those obtained from detrital muscovite in a Neoproterozoic-Cambrian sedimentary sequence in the Caledonian terrane, suggesting that the HMS was exposed by latest Neoproterozoic time and supplied detritus to the sedimentary units. The HMS is interpreted to represent a fragment of an accretionary complex, similar to the Sanbagawa Belt in Japan. It confirms the presence of a major cryptic suture between the Avalon terrane sensu stricto and the now-adjacent Brookville terrane. [source] Dashuigou Tellurium Deposit in Sichuan Province, China: S, C, O, and H Isotope Data and Their Implications on Hydrothermal MineralizationRESOURCE GEOLOGY, Issue 1 2002Jingwen MAO Abstract: Dashuigou, a unique tellurium-dominated deposit over the world, is located in the western margin of the Yangtze cra-ton in southwestern China. It is characterized by high-grade tellurium accompanied by bismuth, gold, silver, and sulfur, and occurs in the area of less than one km2. The mineralization is divided into three stages, i.e. (1) tellurium-bearing pyrrhotite,pyrite stage, (2) tetradymite stage, and (3) auriferous quartz veins stage. Tellurium mineralization coexisting with bismuth, silver, selenium, and gold predominantly develops in the stage 2, while the stage 1 is enriched only in sulfur and iron, and the stage 3 is very weakly mineralized with gold. The ,34S values of sulfides in the ore of the deposit vary in a narrow range of ,3.1 - +2.8 per mil with ,3.1 - +2.8 per mil for the stage 1 and ,0.5 - +2.1 for the stage 2, showing the isotopic characteristics of mantle derived sulfur. The ,13C values of vein dolomites vary from ,5.3 to ,7.2 per mil, with ,5.3 - ,6.6 per mil for the stage 1 and ,5.3 - ,7.2 per mil for the stage 2, which are significantly different from those of surrounding Triassic marble with ,13C values of ,0.3 - +2.8 per mil, and show characteristics of mantle derived carbon. The ,18O values of vein dolomites range from +10.2 to +13.1 per mil, which are higher than those of carbonatite, but lower than those of the marble. Their corresponding ,18Owater values are +0.6 - +3.9 per mil, with +2.7 - +3.8 per mil for the stage 1 and +0.6 - +3.9 per mil for the stage 2. The data implies that these vein carbonates were formed by the mixing fluids of magmatic or mantle source with meteoric or formation water. The ,18O values of ore-forming fluids responsible for the formation of vein quartz are estimated to be +3.2 to +6.8, the ,D values of inclusion fluids of the quartz are measured to be ,54 to ,82 per mil. All those stable isotopic data suggest the involvement of the fluids from mantle and/or mantle-derived magmas through fault system in the forming process of the Dashuigou tellurium deposit. [source] ON THE WHITE AND COLOURED MARBLES OF THE ROMAN TOWN OF CUICUL (DJEMILA, ALGERIA)ARCHAEOMETRY, Issue 4 2010F. ANTONELLI This paper reports the results of an archaeometric study of the local and imported marbles found in the Roman town of Cuicul (now Djemila, Algeria), a research project funded by the Sixth Framework Programme of the European Union. Of the few imported coloured lithotypes that have been found, four are of Greek origin and one was imported from Asia Minor. In addition, two other classical Roman coloured stones found on the site are probably of local North African origin (most likely one from Numidia and one from Algeria). With regard to the grey and white marbles employed in the statuary and architecture, petrographic study in thin section and the ,13C and ,18O isotopic data emphasize the frequent use of the local fine-grained lithotype from Filfila (Skikda) together with imported Greek lithotypes (i.e., Pentelic marble, the dolomitic variety of Thasian marble, and Parian marble from Lakkoi) as well as different varieties of the so-called ,greco scritto', whose provenance in some cases still remains uncertain. In fact, the petrographic and geochemical features of the marbles do not always match those known for the classical ,greco scritto' from the quarry of Cap de Garde, near Annaba (Algeria). [source] | |||||||||||||||||||