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1.
Hyblean limestone of Oligo-Miocene age was widely used as a construction material in the architectural heritage of Eastern Sicily (Italy). Among them, the so-called Pietra Bianca di Melilli (Melilli limestone) and Calcare di Siracusa (Syracuse limestone) were prized for their attractive appearance, ease of quarrying, and workability. Syracuse limestone shows general weathering, whereas Melilli limestone is better preserved, and only differential erosion or superficial exfoliation can be detected in monuments. The cause of the different behavior of these two limestones was investigated from the petrographic and petrophysical points of view. The saturation coefficient is higher in Melilli limestone, and ultrasound measurements indicate that it is less compact than Syracuse limestone, so that Melilli limestone could deteriorate more easily than Syracuse limestone. However, pore interconnections and the size of very small pores play the main role in the durability of both materials. The “irregularity” of the Syracuse pore system and its greater number of micropores hinder water flow through the exterior, promote stress in pore structure, and favor the development of scaling, as confirmed by salt crystallization tests. In Melilli limestone, the low concentration of micropores and fast water evaporation allow solutions to reach the surface more easily, resulting in less damaging efflorescence.  相似文献   

2.
Three generations of Quaternary conglomerates formed by cementation of glacial gravels are found in drift of the Appalachian Plateau in south-central New York. Postglacial conglomerates have been locally cemented by carbonate minerals within limestone-bearing (erratic-rich) gravels of Late Wisconsin (Woodfordian) age. Conglomerates cemented during the Mid-Wisconsin interstade occur as numerous fragments in erratic-rich Late Wisconsin drift, and as a single in situ mound near Syracuse. Mid-Wisconsin conglomerate contains fragments of a still older conglomerate believed to be of possible pre-Wisconsin (Sangamon) age. Both postglacial and Mid-Wisconsin conglomerates were cemented in the same manner, as a result of diagenetic processes in the vadose zones of limestone-bearing terraces. Information gleaned from conglomerate fragments indicates that Early Wisconsin drift was similar to Late Wisconsin drift; the Early and Late Wisconsin glaciations and deglaciations of the plateau probably proceeded in much the same fashion.  相似文献   

3.
Man-environment relations in the ancient Greek world, as now, were complex interactions. To understand them, we need to study a range of physical features and man's impact on the setting. The underlying geological reality of this area is karst, which is widely distributed, dominating Greece, the southern half of Turkey, and southern Italy and Sicily, where the Greco-Roman cities that we study were located. Year-round water from karst springs was important because of scarce rainfall, intense evaporation, and infertile soil—none under human control. Examples from the Greek mainland (Corinth), an Aegean island (Rhodes), Turkey (Priene), and Sicily (Syracuse) are selected and described to suggest the way that karst water potential played an important role in site selection and development. A wider look at criteria for urban location and a new classification of urban patterns help to revise conventional understandings of these ancient cities. In conclusion, some modern findings about the interaction between city and setting suggest new research agendas for geologists and engineers, ancient historians and archaeologists, and water policy makers—preferrably working together.  相似文献   

4.
A paucity of literature currently exists pertaining to the high-resolution geographic distribution of metal contaminants across urban areas. Thousands of soil samples were collected across Syracuse, NY to secure empirical evidence about such geographic distributions. Metal measurements were made with XRF technology, with quality assessments based upon replicate samples as well as ICP technology summarized here. Both metal covariations and their spatial structure are described, followed by mapping of selected metal measurements based upon sample points, as well as census block group and census tract aggregates. A simple comparison is presented between certain of these empirical results and a selected non-urban landscape (a river floodplain). Finally, implications drawn from the empirical evidence presented include covariation assessments with selected census data that serve as surrogates for poverty.  相似文献   

5.
Halite brine (saturation ranging from 45 to 80%) lies within glacial sediments that fill the Onondaga Trough, a bedrock valley deepened by Pleistocene glaciation near Syracuse, New York State, USA. The most concentrated brine occupies the northern end of the trough, about 10 km downgradient of the northern limit of halite beds in the Silurian Salina Group, the assumed source of salt. The chemical composition of the brine and its radiocarbon age suggest that the brine originally formed about 16,700  years ago through dissolution of halite by glacial melt water and later mixed with saline bedrock water. Two hypotheses regarding the formation of the brine pool were tested through variable-density flow simulations using SEAWAT. Simulation results supported the first hypothesis that the brine pool was derived from a source in the glacial sediments and then migrated to its current position, where it has persisted for over 16,000  years. A second hypothesis that the brine pool formed through steady accumulation of brine from upward flow of a source in the underlying bedrock was not supported by simulation results, because the simulated age distribution was much younger than the age estimated from geochemical modeling.  相似文献   

6.
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7.
An archaeometric study of the stone materials employed in the Late Baroque historical monuments of the ancient city centre of Catania was carried out. Lithological maps of a selection of monuments, transferred to a digital format, revealed that the stone materials are both magmatic and sedimentary rocks, the colours of which are matched in a peculiar type of bichromy. Particular attention focused on sedimentary rocks, which consist of various types of limestone quarried near the city of Syracuse (Hyblean Plateau, south-eastern Sicily). Carbonate rocks were characterised in terms of mineralogy, petrography and geochemistry, by studying rock samples from both monuments and historical extraction sites. Results showed that, although only one name was historically attributed to the above lithotypes (i.e. “Pietra di Siracusa‘’), they were quarried from many locations and, as they belong to various geological formations, they therefore exhibit great variety. In order to examine the durability of Hyblean limestones employed in works of cultural heritage interest, salt crystallisation tests were carried out according to standard procedure norms (UNI EN 12370 (1999) Determination of resistance to crystallisation of salts, 6p). Results are consistent with the forms of deterioration observed in the monuments, and highlight the close relationship between textural characteristics and damage. Our purpose is to provide a basic tool, which may be useful both for conserving monuments of cultural heritage and for their restoration.  相似文献   

8.
Associations between Pb, Zn, Fe and Mn in soils and indoor dusts in urban Syracuse, NY have been investigated at different levels of spatial aggregation. The concentrations of these elements of interest (EOI) in 3566 soil samples were mapped across the city to investigate variations in concentration potentially associated with specific city locations. Indoor floor dust loadings for the EOI determined at 433 residences were mapped in a similar fashion. Pearson product correlation coefficients at different levels of soil sample aggregation (individual sampling points, block group averages, and census tract (CT) averages), consistently demonstrated a strong correlation between soil Pb and Zn concentrations. Correlations between Pb and both Fe and Mn soil concentrations were also significant. However, the correlation between the Fe and Mn floor dust loadings was much stronger than that for soil, as were the correlations between the Pb and both the Fe and Mn dust loadings. The correlation between the Fe and Zn floor dust loadings was far less significant. Surprisingly, most of the correlations between the paired EOI in the dusts and soils at the individual homes were mostly not statistically significant. The two correlations of any significance, and these were between the Pb in soil and the Pb in the dust, and between Pb in dust and Zn in soil.  相似文献   

9.
Residual strain, a self-equilibrating recoverable strain that remains in rocks even after external forces and moments are removed, is found NNW of the folded Appalachian plateau in the Devonian Onondaga limestone and the Silurian Lockport dolomite and Grimsby sandstone of western New York. This residual strain is manifest upon overcoring by a NNW directed maximum expansion of the limestone and sandstone and a random maximum expansion of the dolomite. Strains, recorded with strain gauge rosettes bonded to outcrops, are as high as 200 με (microstrain). Double overcoring of the sandstone and dolomite relieves smaller strains of the same orientation as the initial overcore. X-ray analysis of the Grimsby sandstone shows that the elastic residual strain locked in quartz grains is characterized by a NE principal extension of 60 με and a 10–30 με NW principal compression oriented 30° counterclockwise from the NNW compression indicated by overcoring. Sonic velocity tests on samples in the lab indicate that Grimsby sandstone is anisotropic with a NNW maximum P-wave velocity of 4.05 km/sec. This anisotropy correlates with the residual strain in Grimsby sandstone. Mechanical twinning of calcite within both the Onondaga limestone and Grimsby sandstone indicates that the rock contains a permanent compressive strain of less than 2% in the NNW direction. The permanent strain becomes progressively smaller in a series of samples from Syracuse to Buffalo, New York. The development of solution cleavage in Onondaga limestone also indicates a NNW compression. No evidence of permanent strain was found in the dolomite. The NNW compression of the limestone and sandstone is normal to the fold axes of the Appalachian foreland fold and thrust belt. This geometric relationship indicates that the residual strain well beyond the outermost Appalachian folds was caused by the same tectonic stresses responsible for folding, the Appalachians during the late Paleozoic. Strain within the Appalachian plateau below the Silurian salt horizon suggests either the presence of a second décollement in, perhaps, Ordovician shales or a general NNW shortening of the crust under the Appalachian plateau.  相似文献   

10.
The up-to-date petrological and microtextural information on the Ligurian Alps indicates that the metamorphic rocks from the oceanic lithosphere and the paleo-European continental margin underwent an alpine-type metamorphic evolution characterized by low dT/dP gradients. In particular, rocks from the Ligurian-Piedmontese oceanic lithosphere underwent an alpine metamorphism typical of alpine-type blueschist rocks. The distribution of the alpine metamorphic facies in paleo-European continental margin is closely related to the structural position of the different tectonic units. The prograde evolution frequently preserves paragenetic and textural relics of the earlier parageneses. If relics of the earlier parageneses are preserved, the rock exhibits continuous prograde reactions confirmed by strong compositional zoning of the metamorphic minerals. Therefore, these reactions lead to chemical and microtextural equilibrium relations, between the minerals, in limited domains of the rocks (microtextural sites). The main compositional aspect of coronitic textures is the mineral zoning, particularly when the minerals of the coronas are the consequence of a wide range of solid solutions. In such cases, the reacting minerals are armored and the kinetics are lowered. The prograde metamorphic evolution, which involved the rocks from the oceanic lithosphere and the paleo-European continental margin, is quite consistent with a subduction-type geodynamic process in different ages during alpine times.Mineral Abbreviations Ab albite - Acm acmite - Alm almandine - Amp amphibole - Ant antigorite - Act actinolite - Bt biotite - Ced celadonite - Chl chlorite - Chlrm chloromelanite - Chltd chloritoide - Cpx clinopyroxene - Di diopside - Ep epidote - Fo forsterite - Gl glaucophane - Gnt garnet - Gro grossular - Hed hedenbergite - Hor hornblende - Jd jadeite - Kfld K-feldspar - Lau laumontite - Lw lawsonite - Ma margarite - Mu muscovite - Omp omphacite - Pa paragonite - Ph phengite - Pl plagioclase - Py pyrope - Pyr pirophyllite - Prh prehnite - Pump pumpellyite - Qz quartz - Rieb riebeckite - Rut rutile - Tchu titanclinohumite - Tc talc - Tr tremolite - Zeo zeolites - Zo zoisite - Wm white mica  相似文献   

11.
The Aiketik Group, distributed at the western end of the South Tianshan Mountains, China, is an important lithostratigraphic unit involved in the South Tianshan orogen. It is separated from the adjacent rocks by faults. Generally, the geologists ascribed it to the Upper Carboniferous according to Pseudostaffella sp., Profusulinella sp. and Fusulinella sp. found from the limestone and sandy limestone of Aiketik. Our radiolarian fossils were obtained from the chert samples collected from the Haladaok section located at the upper Tuoshihan River. The fossils mainly include Albaillella undulata Deflandre, Albaillella paradoxa Deflandre, Albaillella sp. aff. A. paradoxa Deflandre, Albaillella sp. cf. A. deflandrei Gourmelon, Albaillella sp., Albaillella excelsa Ishiga, Kito and Imoto (?), Belowea variabilis (Ormiston et Lane), Callella cf. C. parvispinosa Won, Entactinia cf. E. tortispina Ormiston et Lane, Entactinia aff. E. tortispina Ormiston et Lane, Entactinia variospina Won, Entactinia sp., Eostylodicty  相似文献   

12.
Two anhydrous equilibria can be written among the components of stilpnomelane, chlorite, white mica and quartz, namely 89 daphnite+131 Fe-celadonite+190 quartz=96 stilpnomelane+71 muscovite, and amesite+Mg-celadonite=muscovite+clinochlore. We assume that the free energy change of reaction, ΔG=ΔGo+ΣRT lnaij, is approximated by ΔG=A?BT +C(P?1)+ΣRT lnaij, where ΔGo is the free energy change of the end-member components at temperature T and pressure P, ai is the activity of component i whose coefficient in the equilibrium is j, and A, B and C are constants to be determined. Values of C can be approximated by the change in volume on reaction, namely C=406.517 J/bar for the first reaction and C=0.613 J/bar for the second reaction. Constants A and B were determined by using six occurrences of the assemblage stilpnomelane–chlorite–white mica for which P–T have been otherwise estimated. Using solution models from the literature, linear regression gives for the first equation A=?6118.269 kJ, B=?4584.09 J/K, and for the second equation A=19.397 kJ, B=66.72 J/K. These values predict P–T within 0.5 kbar and 25 K for all occurrences, and appear reasonably robust relative to probable analytical errors. P–T are determined by intersection of the curves generated by given compositions in P–T space. Fine-grained and/or zoned chlorite and white mica make application of the geothermobarometer difficult in some instances, but our work in the Bathurst region of New Brunswick suggests that, with patience and care, useful analyses can be obtained, and the database for the geothermobarometer greatly expanded.  相似文献   

13.
The ammonite and inoceramid bivalve faunas of the Davutlar Formation of the Devrekani–Kastamonu area in central-north Turkey, are described. The formation yields an ammonite assemblage of Pseudophyllites indra (Forbes, 1846), Pachydiscus (Pachydiscus) haldemsis (Schlüter, 1867), Pachydiscus (Pachydiscus) oldhami (Sharpe, 1855), Didymoceras binodosum (Kennedy and Cobban, 1993), Bostrychoceras polyplocum (Roemer, 1841) and Baculites alavensis Santamaria Zabala, 1996. The inoceramid assemblage is Cataceramus subcompressus (Meek and Hayden, 1862), Cataceramus goldfussianus (d'Orbigny, 1846), Platyceramus vanuxemi (Meek and Hayden, 1860), Cataceramus cf. mortoni (Meek, 1876), Cataceramus pteroides (Giers, 1964), Cataceramus aff. barabini (Morton, 1834), Platyceramus pierrensis (Walaszczyk et al., 2001), “Inoceramus” convexus Hall and Meek, 1856, Cordiceramus heberti (Fallot, 1885), “Inoceramus” tenuilineatus Hall and Meek, 1856, “Inoceramus” borilensis Jolkicev, 1962, as well as some forms with no or equivocal specific affiliation. Both ammonite and inoceramid faunas suggest an early Late Campanian age for the formation, most probably Bostrychoceras polyplocum and Didymoceras donezianum ammonite Zones / Cataceramus subcompressus and “Inoceramus” tenuilineatus inoceramid Zones. Both ammonite and inoceramid assemblages are well represented throughout the Euramerican biogeographical region.  相似文献   

14.
The strain associated with the Horn Head Slide, a major tectonic break in the Dalradian rocks of NW Ireland, is recorded by pebbles in an adjacent quartzite horizon. Mean X/Y ratios of the deformed pebble shapes in excess of 8.0 are seen closest to the slide and the field of three-dimensional shapes lies along the K = 1 line. The usual methods of separating initial shape ratio (Ri) and tectonic strain ratio (Rs) from the deformed shape ratio (Rf) of ellipsoidal markers are based on measurements of variation in fluctuation (e.g., the (Rf/φ technique). However, due to the high X/Y strains in this situation and since the pebbles initially lay parallel to bedding and to a principal plane of the finite strain ellipsoid, fluctuation is generally very low. Thus, except for the least deformed X/Y data, the Rf/φ technique is inapplicable and other methods are used. For X/Y data with mean (Rf > 4.0: Rs is calculated as the harmonic mean of Rf; maximum Ri values only are obtained from the range of Rf data. For all Y/Z and X/Z data: Ri is calculated from the logarithmic range (ωlog) of Rf; Rs is simply obtained from the geometric mean of Rf modified by Ri. It is concluded from this that a varying prolate tectonic strain (K - 1.5) reaching X/Y values in excess of 8.00 was coaxially superimposed on an initial oblate shape fabric to produce the present field of deformed pebbles in the quartzite near the slide.  相似文献   

15.
The Wupata‘erkan Group, also called Wupata‘erkan Formation, distributed in the South Tianshan, Xinjiang,China, mainly consists of gray and dark gray fine-grained clastic rocks, interlayered with volcanic rocks, carbonates and cherts. Some ultra-basic rocks (blocks) punctuate the formation. The formation was variously assigned to Silurian-Middle Devonian, Silurian-Lower Devonian, and pre-Devonian, mainly based on Atrypa bodini Mansuy, Hypothyridina parallelepipedia (Brour.) and Prismatophyllum hexagonum Yoh collected from the limestone interlayers, respectively.However, radiolarian fossils obtained from 24 chert specimens of the Wupata‘erkan Group, mainly include Albaillella sp.cf. A. undulata Deflandre, Albaillella sp. cf. A. paradoxa Deflandre, Albaillella cf. A. deflandrei Gourmelon, Albaillella sp. cf. A. indensis Won, Albaillella sp. cf. A. excelsa Ishiga, Kito and Imoto, Albaillella sp. and Latentifistulidae gen. et. sp.indet., are earliest Carboniferous and Late Permian. The earliest Carboniferous assemblage is characterized by Albaillella sp. cf. A. undulata Deflandre, Albaillella sp. cf. A. paradoxa Deflandre, Albaillella cf. A. deflandrei Gourmelon and Albaillella sp. cf. A. indensis Won, and the Late Permian assemblage by Albaillella sp. cf. A. excelsa Ishiga, Kito and Imoto. This new stratigraphic evidence indicates that the Wupata‘erkan Group is possibly composed of rocks with different ages from Silurian to Permian, and therefore, it is probably an ophiolite mrlange. The discovery of Late Permian Albaillella sp. cf. A. excelsa provides more reliable evidence supporting the existence of a Permian relic ancient oceanic basin in the western part of Xinjiang South Tianshan.  相似文献   

16.
In the present study, the modified Sverjensky–Molling equation, derived from a linear-free energy relationship, is used to predict the Gibbs free energies of formation of crystalline phases of α-MOOH (with a goethite structure) and α-M2O3 (with a hematite structure) from the known thermodynamic properties of the corresponding aqueous trivalent cations (M3+). The modified equation is expressed as ΔG0f,MVX=aMVXΔG0n,M3++bMVX+βMVXγM3+, where the coefficients aMVX, bMVX, and βMVX characterize a particular structural family of MvX (M is a trivalent cation [M3+] and X represents the remainder of the composition of solid); γ3+ is the ionic radius of trivalent cations (M3+); ΔG0f,MVX is the standard Gibbs free energy of formation of MvX; and ΔG0n,M3+ is the non-solvation energy of trivalent cations (M3+). By fitting the equation to the known experimental thermodynamic data, the coefficients for the goethite family (α-MOOH) are aMVX=0.8838, bMVX=?424.4431 (kcal/mol), and βMVX=115 (kcal/mol.?), while the coefficients for the hematite family (α-M2O3) are aMVX=1.7468, bMVX=?814.9573 (kcal/mol), and βMVX=278 (kcal/mol.?). The constrained relationship can be used to predict the standard Gibbs free energies of formation of crystalline phases and fictive phases (i.e. phases that are thermodynamically unstable and do not occur at standard conditions) within the isostructural families of goethite (α-MOOH) and hematite (α-M2O3) if the standard Gibbs free energies of formation of the trivalent cations are known.  相似文献   

17.
A new fossil microbiota yielding eukaryotic Tappania is described from the Mesoproterozoic Kamo Group of the Central Angara Basin, Siberian Craton. The assemblage also includes Valeria, Satka, Lophosphaeridium, Pulvinosphaeridium, Miroedichia, Osculosphaera, Tasmanites, Obruchevella, Glomovertella, as well as branching and anastomosing filamentous microfossils of putative fungal affinities and peculiar short trichomes, that together substantially increase the biodiversity of the Tappania Association. Stratigraphic position and geochronological constraints indicate a relatively young Late Mesoproterozoic age of the Tappania-bearing sediments. There appears to be a continuity between the Tappania Association and the Neoproterozoic microbiota, the latter being firmly rooted in the Late Mesoproterozoic.  相似文献   

18.
Assuming a relation of “b” to stress state, the possibility of globe-wide stress variation and transmission was investigated. The NOAA earthquake data file served to determine the temporal change in “b” of log N = a − bM from 1963 to 1975.Periods of six to eight years are observed in the b-values (stress pattern) for most circum-Pacific areas (South America, Tonga, Kermadec, New Hebrides, Kamchatka and Eastern Aleutians).In the Kurils, fore- and aftershock sequences of large earthquakes seem to mask any characteristic global pattern that might exist. These sequences exhibit low b-values (high stress) through the time of foreshocks and early stages of aftershocks, followed by rapid increase in b-values (decrease in stress).Use of a worldwide earthquake data file clearly yields less resolution of the temporal “b” variation than the use of local network studies published by other authors.Incidental to the study, 1124 earthquakes of the NOAA data file yield the Ms − mb relations: Ms = 1.16mb − 0.835 for 4.5 mb 6 and: log10Ms = 0.1432mb − 0.0629 formb > 6 with correlative coefficients of 0.994 and 0.992 respectively.  相似文献   

19.
When load acts on a circular foundation on or in a dense sand, average contact pressure on the lower surface of the foundation is q and settlement of the foundation is s. Diameter and depth of the foundation are B and Df. When the sand, B and Df are given, we can know the relation between q and s/B by, e.g. a loading test, i.e. the relation is determined by B and Df for the sand. Using the results of numerical analyses, we express a relation between q and s/B up to s=0.1B by functions of a single variable which is a linear combination of B and Df. Consequently when two foundations have different B's and different Df's but have the same value of the variable, the relations are the same. Then we examine whether the functions can express the results of eleven tests of model foundations of wide range of B and/or Df. In all the tests, the relations are expressed with sufficient accuracy. Copyright © 2005 John Wiley & Sons, Ltd.  相似文献   

20.
中国西北C-3植物的碳同位素组成与年降雨量关系初探   总被引：2，自引：0，他引：2  
 本文对不同年降雨量环境下生长的藜、独行菜、魁蓟和平车前这4种常见C-3植物的δ13C进行了分析,发现这4种C-3植物的δ13C组成都表现出随年降雨量减少而变重的趋势,其中藜和独行菜的碳同位素组成对降水变化的响应相对要较其它2种植物强烈得多。藜、独行菜和魁蓟的δ13C组成与年降雨量有显著的线性关系,平车前碳同位素组成与年降雨量没有显著的相关性,表明藜、独行菜和魁蓟的δ13C组成可作为年降雨量的替代性指标,平车前的δ13C组成不能作为年降水的替代性指标。  相似文献   

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