The role of humic substances in the formation of marble patinas under soil burial conditions

The present work aim to study the effect of burial on the photoluminescnece (PL) spectra of white, crystalline marble surfaces and the physicochemical processes that take place at the marble—soil interface. The PL was studied by an argon ion laser beam, focused through a microscope objective onto the sample, offering a spatial resolution of 3 μm. Long-buried (time scale of 1,000 years) surfaces show a red (at 610 nm) emission due to Mn²⁺, which is also shown on fresh marble spectra and an additional broadband blue-green (380–530 nm) one. Electron paramagnetic resonance (EPR) spectroscopy and laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) indicate that the latter emission originates from humate complexes. The complexes are most probably Ca-humates, the humic substances found in the soil and the divalent calcium cations released by the dissolution of marble calcite. Finally, the examination of recently (time scale of 50 years) buried surfaces shows that the blue-green emission and consequently the presence of humates in marble patinas are not affected by the soil organic matter content. Soil acidity however, is a critical factor, with a total absence of the blue-green emission at pH values lower than 6.     

Soiling of limestone in an urban environment characterized by heavy vehicular exhaust emissions

The inorganic and organic chemical composition of weathering sulphate patinas on the limestone walls of Emmanuel College, Cambridge, UK, have been analysed by FT-IR spectroscopy, pyrolysis gas-chromatography/mass spectrometry and scanning electron microscopy. The College location is characterized by heavy vehicular exhaust emissions including those from diesel powered public transport vehicles due to its proximity to the main Cambridge coach station. A complex mixture of gaseous and particulate air pollutants are found deposited in the weathering patinas including organic compounds (such as PAHs), which represent markers for present-day vehicular pollution. Slight differences in composition between patinas collected at different heights on the building facades with, in particular, more evidence for a biogenic overprint in samples collected at roof level as opposed to ground (street) level are found. Analytical results confirm how building stones in urban areas acted in the past and still do today as passive repositories for any kind of gaseous and particulate air pollutant present in the surrounding atmosphere; accordingly, weathering patinas are slowly changing their composition to accommodate new classes of present-day air pollutants.     

Petrographical and geochemical investigation of the Triassic marbles associated with Menderes massif metamorphics,Kavaklıdere,Muğla,SW Turkey

Vast marble deposits occur in a cover sequence of the Menderes Massif, SW Turkey. Four major marble deposits are recognized in Mu?la province based on the stratigraphic levels. These are Permo-Carboniferous aged black marbles (1), Triassic aged marbles (2), Upper Cretaceous aged marbles (3), and Paleocene aged pelagic marbles (4). This study deals with Triassic aged marbles of the southern part of the Menderes Massif. The Triassic marbles from SW Turkey consist of two big marble horizons in the Çayboyu (ÇM) and Kestanecik (KM) regions. The characteristic samples are collected from different stratigraphic levels in marble deposits in the ÇM and KM horizons. Mineralogical and major, trace, and rare earth element (REE) analyses of marble, limestone, and schist were conducted on these samples to reveal their petrographical and geochemical characteristics. The ÇM horizon is represented by calcitic marble layers. Nickel, cobalt, manganese, and iron elements filled in fractures, fissures, and intergranular spaces of calcite crystals and these elements give the pinky colour to the marble from the ÇM horizon. KM marbles were deformed, metamorphosed, and recrystallized under greenschist facies P–T conditions. As a result of the metasomatic reaction of magnesium and manganese rich fluids with marbles, dolomite, and manganese, minerals such as rhodochrosite and pyrolusite have crystallized along vein walls and layers in the KM horizon. Dolomitization was determined in KM marbles, whereas ÇM marbles show the character of limestone. MgO, MnO, Fe₂O₃, Ni, and Zn contents of marbles from the KM horizon are higher than those of ÇM marbles due to metasomatic reactions. The Sr content in white coloured marbles ranges between 11.20 ppm and 112.20 ppm and this concentration reaches up to 272.70 ppm due to metasomatic reactions and fluid intake. The REE content of Triassic marbles is independent of the abundance of carbonate and the REE enrichment observed due to syn-metamorphic fluid flow. The significant negative Eu anomaly in REE patterns indicates that the protoliths of Triassic marbles are carbonate rocks of sedimentary origin.     

Chemical Zone of Nephrite in Alamas,Xinjiang, China

The Hetian deposit, located south of the Tarim Basin in Xinjiang, China, is one of the world's largest dolomite-related nephrite deposits. In the Alamas orebody of the deposit, nephrite occurs as veins or lenses along faults or fissures of the adjacent dolomitic marble. Chemical analyses using electronic microscope probe analysis and X-ray fluorescence spectroscope were carried out on nephrite and dolomitic marble samples collected from a cross section in Alamas to investigate zonal structure of the orebody. The nephrite in Alamas is predominately composed of tremolite with minor calcite, titanite and phlogopite, and that dolomitic marble is relatively pure with a FeO content less than 0.20 wt. %. Contents of color-inducing elements, such as Fe, Mn, and Cr, increase gradually as color changes from white through white-green and then to green, resulting in the formation of color-distinctive zones. Tremolite grain size increases as color changes from white through white-green to green. The trend may be consistent with temperature changes from dolomitic marble to granodiorite, which, in turn, suggests that both change in color from white to green and variations of grain size with increasing temperature resulting in formation of the nephrite zonal structure. Both nephrite zonal structure and minor minerals, such as calcite, titanite and phlogopite found in the contact, indicate that this dolomite-related nephrite orebody is of a metasomatic origin under assumed pressure of 100–200 MPa and temperature <550°C.     

Analysis of spalling failure in marble rock slope: a case study of Neyriz marble mine,Iran

The expansion of the Neyriz marble mine into deeper levels caused an unexpected failure particularly in the toes of lower benches. This phenomenon can impact the overall stability of the quarry and results in undesirable environmental and technical consequences. To understand the failure mechanism, a comprehensive study including—laboratory testing, in situ field testing and theoretical analyses are carried out. The theory of the brittle failure which was mainly developed based on the experiences gained during excavation in granite rocks is adopted and augmented in this study to explain the governing mechanism of failure. Mechanical properties of the marble are determined using conventional rock mechanics tests, and the in situ stress field was evaluated using a modified under coring test. Analyzing the laboratory and field data with the available empirical criteria for brittle failure shows that the level of stress in the lower bench is high enough to initiate the brittle failure. Finally, constitutive models developed for this failure mode are adopted in conjunction with numerical modeling to investigate the observed failure in the quarry. Two modeling strategies, based on elastic and elastic–plastic analyses, are considered. Comparing the predicted failure surface with the observed failure profile, it can be concluded that the brittle failure criteria can very well capture the failure mechanism in this marble quarry. This shows that the criteria proposed to describe spalling failure around underground excavation in granite can be effectively employed for assessing the brittle failure in deep open cast and quarry mines in good quality rocks such as marble.     

Electrical resistivity imaging over natural (in situ) geological samples using physical model studies

To understand the characteristic responses of natural geological samples, viz., black granite, green marble, and graphite sheet, and to have “an a priori” knowledge of their physical property through electrical resistivity imaging, the physical model laboratory setup has been established to conduct scale model studies over targets of finite dimensions and resistivities. The present experiment involves IRIS make SYSCAL Pro-96 measuring system using 48 electrodes with 2-cm interelectrode separation in the laboratory model tank. In the present communication, we have presented the 2D cross section images using Wenner, Wenner–Schlumberger, and dipole–dipole array configurations over the resistive (granite, marble) and conductive (graphite) sheets. In the case of resistive target (black granite sheet, green marble), the combined usage of dipole–dipole and Wenner–Schlumberger arrays provided more accurate measures on target parameters, i.e., the combined usage of both the arrays is preferable in searching high-resistive targets beneath the low-resistive ones over burden. The shape of the resistive target (green marble sheet) is inappropriate when the thickness of the target is greater than one half of the minimum array separation. As the thickness of the target increases, the signatures of the target become feeble, and hence, the shape of the resistive target is not properly reflected in the corresponding tomogram. The response over graphite sheet indicates that the true parameters of the target are not reflected in the cross section, and the existence of the low-resistive (high-conductive) target in the host medium (water) deviates the resistivity of the medium. The target parameters from the cross section using dipole–dipole array are somewhat correlated with true parameters in the case of thin targets at shallow depths. In the case of the sequence of layers of gravel–marble gravel–sand gravel simulated in a small model tank in the physical model laboratory, the thickness of the high-resistive marble layer beneath the low-resistive gravel layer is enhanced conspicuously because of the significant resistivity contrast between gravel and marble.     

Stable isotopes and archaeological geology: the Carrara marble,northern Italy

The principal marble quarries of Italy for the past 2000 years have been those of Carrara. In Roman times, the marble was exported all over the ancient world. Renaissance quarries were opened up in Seravezza; both the Seravezza and the Carrara quarries have been exploited until today. The correct identification of Carrara marble has always been a problem because it was traded so widely in Roman times and was later used to fabricate broken or lost pieces of classical statuary. Many types of geochemical analysis have been tried in order to find distinctive signatures for the recognition of classical marbles, including trace elements, ESR spectroscopy of Mn, thermoluminescence, and stable isotopic ratios. To date, the most promising has been isotopic ratio analysis of oxygen and carbon.In this study, stable isotopic signatures were investigated as a means for distinguishing: (1) the principal quarry areas of the Carrara Commune: Fossacava, Miseglia, and Torano, and the Seravezza Commune; (2) or merely the largely classical quarries of Carrara from the Renaissance quarries of Seravezza; (3) and, most important, the Carrara quarries from other quarries of Greece, Turkey, Italy, and Tunisia in the classical marble data base.Discriminant analysis (DA) of the isotopic analyses showed that the three quarry areas of a Carrara could not be told apart but that they could be told easily from Seravezza. In addition, a “mineralized” Carrara quarry at Mandria, with buff to yellow rather than white marble, was also distinctive. DA also suggests that Carrara can be told from those quarries with which it is presently confused: Paros, in the Aegean Sea; Marmara, in Turkey; and Pentelikon, near Athens.Sr isotopic analysis showed a range in the Carrara and other marbles of Hettangian (Lower Jurassic) age from 0.70778 to 0.70810 which is very different from values found in Paros and Pentelikon. This suggests that Sr might make a good third discriminator for classical marble.     

Nature and origin of the protolith succession to the Paleoproterozoic Serra do Navio manganese deposit,Amapa Province,Brazil

Until its closure in 1997, the Serra do Navio deposit, located in Amapá Province, Brazil, was one of the most important sources of high-grade manganese ore to the North American market. The high-grade manganese oxide ores were derived by lateritic weathering from metasedimentary manganese protoliths of the Serra do Navio Formation. The local geological context and nature of this protolith succession are not well understood, due to poor surface outcrop conditions, and intense deformation. However, based on similar age, regional tectonic setting and lithology the Paleoproterozoic volcanosedimentary succession that includes the Serra do Navio Formation is widely believed to be similar in origin and laterally equivalent to the Birimian Supergroup in West Africa. For the present investigation several diamond drill cores intersecting the protolith succession were studied. Detailed petrographic and whole rock geochemical studies permit distinction of two fundamental lithological groups comprising of a total of five lithotypes. Biotite schist and graphitic schist lithotypes are interpreted as former metapelites. A greywacke or pyroclastic protolith cannot be excluded for the biotite schist, whereas the graphitic schist certainly originated as a sulfide-rich carbonaceous mudstone. Rhodochrosite marble, Mn-calcite marble and Mn-silicate rock are grouped together as manganiferous carbonate rocks. Manganese lutite constitutes the most probable protolith for rhodochrosite marble, whereas Mn-calcite marble was derived from Mn-rich marl and Mn-silicate rock from variable mixtures of Mn-rich marl and chert.The sedimentary succession at the Serra do Navio deposit is similar to that encountered at many other black shale and chert-hosted Mn carbonate deposits. A metallogenetic model is proposed, predicting deposition of manganese and closely associated chert in intra-arc basins, in environments that were bypassed by distal siliciclastic (carbonaceous mud) and proximal pyroclastic/siliciclastic detritus. Positive Ce anomalies and δ¹³C_VPDB values of − 4.3 to − 9.4 per mill suggest that manganiferous carbonates derived during suboxic diagenesis from sedimentary Mn⁴⁺ oxyhydroxide precipitates. Metamorphic alteration of manganese carbonate–chert assemblages resulted in the formation of Mn-silicates, most importantly rhodonite and tephroite; porphyroblastic spessartine formed where Mn-carbonate reacted with aluminous clay minerals. Microthermometric studies of fluid inclusions in spessartine porphyroblasts suggests that peak metamorphic conditions reached the upper greenschist facies (1–2 kbars and 400–500 °C). Retrograde metamorphism is marked by partial re-carbonation, expressed by the formation of small volumes of rhodochrosite, and Mn-calcite that are closely associated with quartz, chlorite and minor amounts of sulfides related to post-metamorphic veinlets. It is this metamorphosed succession that sourced the high-grade manganese oxide ores during prolonged lateritic weathering.     

The Market Gate of Miletus: damages, material characteristics and the development of a compatible mortar for restoration

The indoor exhibit of the Market Gate of Miletus is unique for an archaeological monument. The reconstruction of the gate was done in such a way that most marble fragments were removed leaving cored marble columns 3–4 cm in thickness. These cored columns were mounted on a steel construction and filled with different mortars or filled with specially shaped blocks of brick combined with mortar. All the missing marble elements were replaced by copies made of a Portland cement based concrete, which is compositionally similar to the original building materials. During the Second World War the monument was heavily damaged by aerial bombardment. For 2 years the Market Gate of Miletus was exposed to weathering, because a brick wall protecting the gate was also destroyed. The deterioration phenomena observed are microcracks, macroscopic fractures, flaking, sugaring, greying, salt efflorescence, calcitic-sinter layers and iron oxide formation etc. The rapid deterioration seems to be due to indoor atmospheric effects, and also by a combination of incompatible materials (e.g. marble, steel, mortar, concrete, bricks etc.). Compatible building materials like mortars or stone replacing materials have to be developed for the planned restoration. The requirements for restoration mortars are chemical-mineralogical and physical-mechanical compatibilities with the existing building materials. In detail this means that the mortar should ensure good bonding properties, adapted strength development and not stain the marble when in direct contact. The favoured mortar was developed with a hydraulic binder based on iron-free white cement and pozzolana based on activated clay. A special limestone and quartz sand mixture was used as an aggregate. The cement was adjusted using chemical additives. Specially designed tests were applied extensively to prove whether the developed mortar is suitable for the restoration of this precious monument.     

Environmental impact on the Roman monuments of Tarragona,Spain

The extant remains of the Roman monuments of Tarragona, Spain are made of different types of Miocenic rocks from the quarries surrounding the city, which vary from calcarenite to bioclastic limestones, showing different degrees of dolomitization, depending on their diagenetic evolution. The decay of these monuments is highly dependent on the mineralogy and the fabric of the stone as well as on the environmental conditions to which the monument subjected. As a consequence, different forms of decay are observed on these monuments, namely, granular disintegration, differential erosion between sparitic and micritic areas of the rock, and development of black crust and orange patinas, some of them attributed to a sulfation process. A number of processes have been established as being responsible for the decay forms observed: sulfation on sheltered areas of the building in the urban environment; differential dilatation because of the NaCl of the marine spray that crystallizes inside the porosity; hydric and thermal expansion of the stone, both related to the amount and crystallinity of the clay minerals forming the rock matrix; and biocolonization on the stone surface. An empirical model is proposed to explain the decay forms studied in relation to these factors (rock and environment).     

西藏昌都热底垄棺墓人骨年代的研究

通过对西藏昌都热底垄石棺墓人骨年代的研究 ,认为热底垄石棺墓的年代应不早于卡若遗址 ,不晚于香贝石棺墓 ,人骨14 C年代应该在距今 4 0 0 0～ 2 4 0 0a之间。并论述了人骨测年的方法以及在野外采样的注意事项。在定年方法上 ,提出对同一样品采用不同的测定技术进行交叉验证 ,以提高数据的可信度研究方法。     

河南新乡宋墓家猫骨骼研究

2012年河南新乡市宋墓考古发掘出土一批动物骨骼,根据种属鉴定和观测比较,该批动物骨骼材料属于家猫.家猫(骨骼)安置于墓主身旁,是墓主入葬时作为饲宠特意放置的.猫骨骼表面没有发现任何人类行为痕迹(切割、砍击等).全部猫骨骼属于同一个家猫个体.保存下来的骨骼材料包括左、右下颌骨;左上颌骨;肱骨、尺骨、桡骨、股骨、胫骨、跖骨等,总计42件家猫骨骼.在家猫动物考古研究中,新乡宋墓家猫是我国同一地点发现家猫骨骼标本数(可鉴定标本数:NISP)最多的地点.特别需要关注的是,在该具家猫骨骼上,首次发现我国家畜考古中"偏侧咀嚼"现象.其特征为:右下颌的P4、m1齿尖,使用磨耗程度远远大于左下颌相同齿位齿尖.磨耗差距最大的部位在m1后尖顶端,右侧比左侧齿尖因磨耗而偏低2.10 mm,右侧m1后尖顶端已磨耗为平面、裸露齿质点,而左侧m1齿尖仍保留有完好锐尖.新乡宋墓家猫在我国动物考古中,还是首次发现以宠物猫进行陪葬的考古学文化现象.我国此前发现的家猫骨骼,主要出土于文化层或灰坑里,可能是被人们丢弃或自然死亡后被埋藏起来的.甚至还有少量猫骨可能是古代人食猫风俗的遗存.而新乡宋墓中的宠物猫,是人们为培养生活伴侣或寄托生活情趣而畜养的,是人们主要为满足精神生活需求而饲养的动物.我国此前动物考古研究有关"宠物"的发现为空白.新乡宋墓出土我国考古中第一只可以确定为宠物的家猫,为今后开展动物考古中有关"宠物"研究开启了良好开端.墓中出土的宠物猫还有严重"偏侧咀嚼"现象,该发现对家畜动物考古材料的演化研究等具有重要意义.     

桐柏蔡家凹岩片内寒武纪高肌虫的发现及其地质意义

本文描述了河南桐柏西北部蔡家凹大理岩岩丰富的高肌虫化石Ｔｏｎｇｂａｉｅｌｌａ ｘｉｎｊｉｅｎｓｉｓ ｇｅｎ．ｅｔ ｓｐ．ｎｏｖ．、Ｘｉａｎｚｈｅｅｌｌａ ｈｅｎａｎｅｎｓｉｓ ｓｐ．ｎｏｖ．和Ｍｏｎｏｎｏｔｅｌｌａ ｃｆ．ｃｈｕａｎｓｈａｎｅｎｓｉｓ Ｈｕｏ ｅｔＳｈｕ及小壳化石Ｃｏｎｏｔｈｅｃａ ｓｐ．共有４属４种。据此确定含化石地层为寒武系,属浅海沉积环境。该生物群的发现为解决桐柏大别造山带与     

Evolution of a calcite marble shear zone complex on Thassos Island, Greece: microstructural and textural fabrics and their kinematic significance

The deformation history of a monophase calcite marble shear zone complex on Thassos Island, Northern Greece, is reconstructed by detailed geometric studies of the textural and microstructural patterns relative to a fixed reference system (shear zone boundary, SZB). Strain localization within the massive marble complex is linked to decreasing P–T conditions during the exhumation process of the metamorphic core complex. Solvus thermometry indicates that temperatures of 300–350°C prevailed during part of the shear zone deformation history. The coarse-grained marble protolith outside the shear zone is characterized by symmetrically oriented twin sets due to early coaxial deformation. A component of heterogeneous non-coaxial deformation is first recorded within the adjacent protomylonite. Enhanced strain weakening by dynamic recrystallization promoted strong localization of plastic deformation in the ultramylonite of the calcite shear zone, where high strain was accommodated by non-coaxial flow. This study demonstrates that both a pure shear and a simple shear strain path can result in similar crystallographic preferred orientations (single c-axis maximum perpendicular to the SZB) by different dominant deformation mechanisms. Separated a-axis pole figures (+a- and −a-axis) show different density distributions with orthorhombic texture symmetry in the protolith marble and monoclinic symmetry in the ultramylonite marble consistently with the observed grain fabric symmetry.     

北京房山大理岩的岩石学微观特征及风化机理讨论

北京地区许多石质古建筑都使用了房山大石窝的大理岩来建造的。本文以汉白玉(白色大理岩)和青白石(青色大理岩)为例,通过薄片镜下观察、X射线衍射(XRD)、X射线荧光(XRF)、扫描电镜(SEM)和电子探针等测试手段,对房山大理岩的岩石学微观特征进行了研究。研究对象为取自房山大石窝的新鲜岩样和取自北京古代石质建筑的风化剥落物。结果证实北京大理岩主要矿物成分是白云石,部分大理岩还含有一定量的石英。基于图像处理软件,对汉白玉和青白石矿物晶体的粒径进行了统计分析。在此基础上,从温度变化、酸雨的溶解、水的溶蚀、微裂隙的盐类充填的角度分析了大理岩的风化机理。相关研究可为北京大理岩石质文物的修复保护提供科学参考。     

Geoenvironmental studies on conservation of archaeological sites at Siwa oasis, Egypt

Siwa oasis is located in the extreme western part of the Egyptian western desert. There are several archaeological sites in the oasis; the most distinct ones are Alexander the Great temple at Aghormi hill and the Gebel El Mota tomb excavations. They have suffered due to deterioration and cracks of different kinds and some parts are getting worse as rock falls occur. From field inspection and lab analysis, it is clear that lithology plays an important role on the extent of damage. Alexander the Great temple was built over the northern edge of Aghormi hill, which consists of two distinct beds—an upper limestone bed and a lower shale one. From field survey and laboratory analysis, the shale is considered as a high expanded bed and weak in its bearing capacity, as its clay content (mainly smectite) experienced swelling due to wetting from the ground water spring underneath. Consequently, the upper limestone bed suffered from map cracking associated with rock falls due to the differential settlement of the swelled lower shale one. The temple was threatened by slope instability and had experienced many cracks. At Gabal El Mota tomb excavations, it was noticed that a comparison of tombs of the same opening size revealed that those that excavated on shale beds had cracked much more than those that excavated on limestone. This may be attributed to the low bearing capacity of excavated shale walls. The remedial measures suggested to overcome the stability problems on these archaeological sites are grouting or construction of retaining walls.     

Instability of an underground ancient tomb due to excavation and its relationship to the temperature and ground water

In order to consider a counterplan to preserve an ancient royal tomb in Kongju, Korea, the deformation of the wall structure, the atmospheric temperature in the tomb, and the groundwater level have been monitored. The long-term measurement of biaxial tilting of the tomb walls revealed that the brick-built subsurface opening had been subjected to severe structural instability. The measured deformation of the tomb was consistent with the displacement of soil around the tomb calculated using a numerical analysis. The instability of the tomb structure is closely related to the rainy season as the deformations measured are several times that in the dry season. A sudden change of temperature inside the tomb exerted an influence on the deformation of the tomb structure as well. It is suggested that the excavation be restored for tourists, the quicklime layer for preventing groundwater infiltration is reinforced, and a constant temperature is kept inside the tomb. This revised version was published online in July 2006 with corrections to the Cover Date.     

Direct observation of microcrack development in marble caused by thermal weathering

One of the properties that makes marble such an excellent construction and ornamental material is its low porosity. It is very difficult for water or decay agents to penetrate the internal structure of materials with no or few pores, so enhancing the durability of these materials. However, environmental temperature fluctuations bring about significant physical changes in marbles that result in an increase in porosity, due to the appearance of new microcracks and the expansion of existing ones. These cracks offer new paths into the marble which make it easier for solutions containing pollutants to penetrate the material. Thermal expansion tests were performed on three different types of marble known as White, Tranco, and Yellow Macael (Almeria, Spain), after which an increase in porosity (from 17 to 73% depending on marble type) was observed, mainly due to crack formation. The structural changes occurring during thermal expansion tests were more significant in the case of White Macael samples, a fact that is not only related to its mineralogical composition but also to the morphology of the grains, grain boundaries and crystal size. Our research suggests that thermally weathered White Macael marble could be more susceptible to decay by other contaminant agents than Tranco or Yellow Macael. The use of hot-stage environmental scanning electron microscopy is proposed as a valid tool for observing, both in situ and at high magnification, changes in the fracture system of building stones induced by thermal stress.     

Introducing a new aspect in marble quarry rehabilitation in Greece

For many years the marble extraction sector of the Greek mining industry has been in conflict with the public, especially in terms of rehabilitation of marble quarry sites. One of the main reasons for that is that the marble extraction sector has been unable to adjust to the existing legislative guidelines for the rehabilitation, such as extensive backfilling and re-vegetation. In the majority of cases these methods fail due to erosion of the backfill soil and adverse climatic conditions. As a result the number of abandoned marble quarry sites is continuously increasing. The present paper suggests a different approach regarding the rehabilitation of marble quarries. More specifically, the paper questions the applicability, the effectiveness, and the social usefulness of the above-mentioned guidelines and suggests the establishment of new land-uses, which are based on an in-depth analysis of the area’s special features, by taking full advantage of its potentials. What is more, the rehabilitation scheme proposes that the new land-uses and the quarrying activity may co-exist and operate simultaneously for a long period of time.     

Limited fluid-rock interaction at marble-gneiss contacts during Cretaceous granulite-facies metamorphism,Seward Peninsula,Alaska

Stable-isotope profiles show that flat-lying marble units acted as impermeable barriers to upward fluid flow in transitional amphibolite-granulite grade rocks of the Kigluaik Mountains, Seward Peninsula, Alaska. The degree of permeability is related to the composition of the marble. The margin of a thick pure dolomite marble chemically reacted with underlying metasyenite (aH₂O=0.2) to form a 2 cm boundary layer of calcite + forsterite by introduction of SiO₂. No fluid penetrated past this reaction front, although the high temperature of metamorphism (800°C) allowed transport of carbon and oxygen isotopes for an additional 2 cm by diffusion through the solid dolomite. A second marble with a higher silica content underwent more decarbonation, which enhanced porosity and lead to a greater extent of isotope transport (2–3 m) in contact with quartzo-feld-spathic gneiss below. An estimate of total fluid flux across the bottom of this marble layer based on the shape of the isotope profile is 1 cm³/cm² directed down, out of the marble. At two other marble-gneiss contacts steep isotopic gradients coincide with lithologic contacts, indicating very little cross-lithology fluid flow. The extent of diffusional transport of isotopes in the marbles is limited and interpreted as indicating the transient presence of a pore fluid, generated by thermally driven devolatilization reactions. No wholesale pervasive advection of C-O-H fluid occurred across the thick, continuous, marble units near the exposed base of the Kigluaik Group section during the entire regional metamorphic cycle. Activities of pore-fluid species were controlled by internal processes. Movement of volatiles and stable-isotopes between contrasting rock-types was dominantly diffusive. Channelized fluid pathways through the marble units developed during uplift and cooling but were not present during peak metamorphism. Heating of the section occurred by conduction, probably from an underlying magma source, and not by advection of a C-O-H fluid.