multichronometric evidence for an in situ origin of the ultrahigh pressure metamorphic terrane of dabieshan china abstract u pb zircon data on gneisses indicate a late proterozoic protolith at 700 ma at bixiling and a late archean to early proterozoic for the shuanghe sheet within the ultrahigh pressure metamorphic terrane of dabieshan china u pb zircon and sm nd dates on the gneisses of the shuanghe sheet constrain a metamorphic peak at 230 ma rb sr and 40ar 39ar analyses of phengite from five gneisses in the bixiling complex yield ages at 198 212 ma overlapping the 190 220 ma age on eclogites the host gneisses record a similar metamorphic evolution as the coesite bearing eclogites since both the peak and the retrograde evolution were contemporaneous this argues for an in situ tectonic relationship

talc magnesite and ti clinohumite bearing ultrahigh pressure meta mafic and ultramafic complex in the dabie mountains china

water solubility in pyrope to 100 kbar the solubility and incorporation mechanism of water in natural almost pure pyrope from dora maira western alps was investigated the infrared spectrum of the natural untreated sample 58 ppm water shows several exceptionally sharp bands in the oh stretching region including a single band at 3601 9 cm 1 and a band system with main components at 3640 5 3650 8 and 3660 6 cm 1 high temperature and high pressure infrared spectra suggest that the two absorption features arise from almost free oh groups in sites with different compressibility and thermal expansivity with the site causing the 3601 9 cm 1 band being much stiffer pyrope samples were annealed in a piston cylinder or multi anvil apparatus for several days in the presence of excess water excess sio2 and excess al2sio5 to determine the equilibrium solubility of water in pyrope to 100 kbar total solubility increases with pressure however this is exclusively due to the high frequency band system while the intensity of the low frequency band decreases with pressure at 1000 c and the oxygen fugacity of the ni nio buffer the bulk solubility can be described by the equation c oh af h2o 0 5exp p v rt with a 0 679 ppm bar0 5 and v 5 71 cm3 mol this equation implies the incorporation of water in the crystal as isolated oh groups with increasing temperature solubility appears to decrease with h 14 kj mol at fe feo buffer conditions solubility is 30 to 50 lower than with the ni nio buffer suggesting that the incorporation of oh is not coupled to the reduction of fe3 possibly the 3601 9 cm 1 band is associated with the tetrahedral oh b defect and the high frequency system with the dodecahedral oh li defect based on the experimentally established solubility model it is estimated that garnet in a hot subducted slab will transport 170 ppm of water into the mantle beyond the breakdown limit of amphibole in a cold slab 470 ppm of water can be incorporated into garnet at the breakdown limit of phengite these numbers imply that a significant fraction of the total water in the hydrosphere has been recycled into the mantle since the proterozoic

index test for the degradation potential of carbonate sands during hydraulic transportation abstract carbonate sands undergo degradation when transported hydraulically from a dredging vessel to the reclamation site risks involved in the production of fines during hydraulic transport are a deterioration of the mechanical properties of the fill in certain areas of the reclamation area where these fines concentrate in order to assess sand degradation in the concrete and road construction industry the micro deval test for fine aggregates was developed in france and canada during micro deval testing aggregates degrade when tumbled in a rotating steel drum with water and steel balls in the canadian standard the steel charge is lower than in the french standard and balls have the diameter of the smallest balls used in the french test during testing the quantity of fines produced is measured this makes the micro deval test an option for assessing the degradation of sand during hydraulic transportation of slurries in the dredging industry three sands are tested two shelly carbonate sands and one quartzic river sand for comparison the carbonate sands were sampled on reclaimed land and had been subjected to hydraulic transportation in pipeline before artificial deposition due to differences in particle shape the carbonate sands and the quartz sand have a different number of contacts with the steel charge in the drum of the micro deval and are not exposed to the same degradation forces during testing it was found that the quartzic sand suffers relatively much degradation as compared to the carbonate sands despite its greater hardness and resistance to crushability the french test appears to create turbulence that promotes floatation of the curved shells of the carbonate sands instead of shell grinding at the bottom of the drum by contact with the steel balls microscopic observations of sand samples before and after testing showed that the french micro deval test is too destructive the test leads to the fragmentation by impact of the quartz sands and the destruction of certain particle types that had survived hydraulic transportation with respect to the canadian test microscopic examination of sand grains before and after testing shows there is still much fragmentation of quartz grains a lower rotational speed combined with a limited steel charge made of uniform balls of a smaller diameter reduces turbulence shell floatability and last but not the least impact forces it produces the desired result a high micro deval loss for the carbonate sands in comparison to that for the quartz sands and a very limited fragmentation of the quartz grains once the slurry reaches its destination the grain size distribution of the fines fraction will influence the mechanical behaviour of mixed sands a procedure is proposed to measure the particle size distribution of the fines fraction produced during micro deval testing field validation is needed to validate preliminary laboratory results

assessment of mineralogical and petrographic factors affecting petro physical properties strength and cracking processes of volcanic rocks abstract microtextural features influence the petrophysical and mechanical properties of rocks including the elastic properties and cracking processes under axial loads volcanic rocks with varying microtextural characteristics and compositions were evaluated to assess the effect of the main constituents mineralogical petrographic and micro structural features on the petrophysical properties elastic properties and strength furthermore detailed analyses were also used to understand the cracking processes under axial loads the analyses of the cracking processes were completed on thin sections obtained from the mechanically tested specimens the results from the quantitative mineralogical and petrographic studies and observations from thin sections revealed that the mineral mass fractions have an effect on the specific gravity and loss on ignition loi values on the other hand unconfined compressive strength ucs and elastic properties are mostly affected by petrographic variables e g mineral content the ucs values tend to decrease with a relative increase in the groundmass with respect to the phenocryst content and vice versa biotite is the only mineral that influences the ucs individually geometric features e g feret s diameter and perimeter of opaque minerals and biotite are determined to be important constituents influencing the young s modulus under axial loads crack propagation is strongly dependent on the proportional distribution of the phenocryst and groundmass it was observed that increasing groundmass content leads to predominantly axial cracks the cracks tend to bend or propagate as a boundary crack when they reach the boundary of an unaltered phenocryst thus axial and shear cracks co exist with increasing amounts of phenocrysts which hinders crack propagation occasionally cracks can penetrate the altered or opaque phenocrysts depending on the degrees of orientation with respect to applied load of the same minerals furthermore the synthesis of the measurements obtained from ucs tests and thin section observations reveals that an increase in the amount of phenocrysts which promote the formation of more shear cracks in addition to axial cracks causes an increase in the radial strain and poisson s ratio the other factors investigated had minor effects on physical and mechanical properties of studied rocks

relationship between density compressive strength tensile strength and aggregate properties of andesites from hungary aggregate properties and strength parameters of four andesites from two operating hungarian quarries of nogradkovesd one lithotype and gyongyossolymos three lithotypes are presented in this paper air dry water saturated and freeze thaw subjected specimens were tested on core drilled cylindrical specimens and the aggregate properties were also determined from the remaining part of the drilled rock blocks tensile strength values rapidly decreased from air dry to water saturated and finally to freeze thaw subjected specimens linear relationships between air dry and water saturated bulk densities and between ucs and modulus of elasticity were found micro fabric influences strength and aggregate parameters of studied andesites fine porphyritic andesite has the highest ucs and tensile strength and the best micro deval results while coarser porphyritic andesite has lower strength and aggregate parameters test results were compared with previously published rock mechanical data of intermediate and basic igneous rocks a good exponential correlation was found between micro deval and ucs values of this paper and previously published data sets but there was no indication that micro deval values correlate well with los angeles values

evaluation of andesite source as armourstone for a rubble mound breakwater hisaronu turkey black sea coast line is a hazardous region especially in winter due to the dominant wave action therefore rubble mound breakwaters protected with armourstone used as ship shelters are vital structures especially for the fishermen the deterioration of the armourstone with time in the form of abrasion and disintegration may result in the failure of the breakwater in this study the properties of the armourstone taken from an andesite quarry and used in the hisaronu rubble mound breakwater were studied both in field and laboratory in order to assess their qualities and long term durabilities based on the in situ observations and laboratory tests the andesite is found to be generally marginal rock ciria cur rdis rers and wet dry strength ratio classifications are in good agreement with the in situ observations and the results of the laboratory tests however rdid average pore diameter and saturation coefficient classifications cannot correctly predict long term durability of the armourstone field studies reveal that block size of the andesite in the quarry increases with depth due to the increase in spacing of the cooling joints of the rock

static and dynamic mechanical properties of sedimentary rock after freeze thaw or thermal shock weathering abstract rocks in engineering works and as building materials are always suffering freeze thaw f t and thermal shock ts weathering and engineering rocks usually involve responses to impact loads from blasting operation mechanized construction and seismic oscillation sedimentary rock distributes extensively and is important for engineering geological and hydrogeological works for a deeper understanding of the f t and ts effects on the rock behaviors physical tests static compressions and dynamic impacts were carried out on red sandstone free from and after artificial f t or ts cycles in this work laboratory tests show the significant physic mechanical deterioration of red sandstone after f t or ts weathering compared to fresh specimens red sandstone after 10 f t or ts cycles performs poorly in both the static compression and shpb impact tests and f t ts induced decreases of ucs and modulus are more remarkable under dynamic impacts than under static loads dynamic mechanical behaviors of both fresh and f t ts weathered red sandstone have distinguishable strain rate effects and water content significantly affects the strain rate effects on mechanical behaviors water and temperature variation play important roles in the rock weathering process in this work water effects during the rock weathering process were summarized as solvent effect and medium effect while temperature variation damaged red sandstone meanly in two ways non uniform thermal deformation of mineral grains and phase transition of water

critical degree of saturation a control factor of freeze thaw damage of porous limestones at castle of chambord france abstract the paper analyzes the petrophysical and mechanical properties of two porous limestones that were used in the construction and restoration works at the castle of chambord in france a unesco world heritage site the original construction material the tuffeau limestone with a total porosity of 45 0 6 and the replacement stone of later restorations the richemont limestone with a total porosity of 29 0 7 were subjected to freeze thaw tests under laboratory conditions to evaluate the role of critical degree of saturation and pore size distribution in frost damage laboratory tests were coupled with in situ measurements of temperature and relative humidity at stone surface at the castle of chambord in situ data show that the stones in the castle experienced several freezing thawing cycles annually the limestone samples under laboratory conditions were subjected to up to 50 freeze thaw cycles under eight different degrees of saturations the total porosity tensile strength ultrasonic pulse velocity the mercury intrusion porosimetry and scanning electron microscopy techniques were employed to analyze the conditions of samples during the cycles the experimental results show that when the degree of saturation of the two studied limestones exceeds 80 85 the freeze thaw damage occurs even after a few freeze thaw cycles the effect of freezing is very fast if the water saturation is sufficient moreover results indicate that these stones have the same critical degree of saturation of about 85 despite the differences in porosity finally the results indicate that the increase in the number of freezing thawing cycles has no effect on the critical degree of saturation but the frost damage is mostly controlled by pore size distribution rather than by total porosity accordingly critical degree of saturation can be defined as an intrinsic stone property

micro textural effects on crack initiation and crack propagation of andesitic rocks abstract the onset of dilation and uniaxial compressive strength ucs of rocks are known to be affected by mineralogical petrographic and microstructural features therefore micro textural variations are essential for understanding variation in strength and failure behaviour of rocks in this study volcanic rock samples with different micro textural characteristics from different locations in turkey were evaluated the mechanical tests revealed considerable variations in unconfined uniaxial compressive strength and the crack initiation ci threshold the ucs ranges between 108 289 mpa and ci ranges between 46 130 mpa detailed quantitative petrographic and mineralogical analyses were carried out on each tested specimen to understand these strength variations additionally microstructural studies were carried out on thin sections before and after mechanical perturbation to analyze 1 the effect of the main constituents of the rock specimens and mineral heterogeneity on crack initiation and propagation and 2 the orientation and distribution of micro and macro cracks formed during laterally unconfined compression the synthesis of mechanical mineralogical petrographic and microstructural data suggests that both the crack initiation threshold and peak strength are influenced by the ratio of the area of fine grain groundmass grains smaller than 200 m to amphibole and plagioclase phenocrysts in addition ci and ucs decrease with an increasing normalized area of biotite phenocryst

quality and durability assessments of the armourstones for two rubble mound breakwaters mersin turkey due to economic reasons natural stones armourstones of various sizes and qualities are very frequently used for the constructions of the breakwaters to protect coastal engineering structures from wave actions deterioration of the armourstones with time in the form of abrasion and disintegration may end up with the damage of the structures therefore it is necessary to investigate the long term performance and quality of the armourstones which should be sound and durable mersin and kumkuyu harbours were constructed using four different limestones obtained from two quarries the limestones have different characters and site performances in this study the material and mass properties of the limestones taken from the quarries with known site performances as armourstones are investigated the site performances and durability of the limestones are compared with the field measurements and laboratory works thus the information obtained is used to assess long term durability of the armourstones the long term performance of the degirmencayi and tirtar upper level limestones are observed to be good whereas it is rather poor for the tirtar middle and lower level limestones comparison between the predicted and observed durabilities of the armourstones indicated that ciria cur rdid rers and wet to dry strength ratio give better results based on their field performances however the prediction of the durability of the limestones is poor in case rdis average pore diameter and saturation coefficient are used

quality assessment of armourstone for a rubble mound breakwater sinop turkey helaldi is a fishing town in the central black sea region where construction of a rubble mound breakwater is being planned the construction of the breakwater requires good quality durable armourstone several laboratory tests are performed for the quality assessment of the two potential armourstone namely limestone and sandstone the quality evaluation of the stones is done on the basis of ciria cur criteria saturation coefficient wet to dry strength ratio and the rock durability index the quality evaluations are then compared with the field performance of both rocks laboratory test results durability assessments and field performance of the rocks indicate that the limestone is a good quality armourstone and it can be used for the breakwater construction however the sandstone is marginal to poor material with very poor field performance and should not be used for the breakwater construction

evaluating chemical equilibrium in metamorphic rocks using major element and sm nd isotopic age zoning in garnet townshend dam vermont usa abstract a quantitative assessment of metamorphic chemical equilibrium derived from correlation of spessartine content and garnet sm nd ages suggests that major element matrix equilibrium was maintained to a first order throughout a ca 40 cm wide rock sample during garnet growth however cm scale sm nd isotopic heterogeneity limits the sm nd age precision required to evaluate more subtle age differences within individual garnet crystals central wafers from 1 3 cm diameter garnet grains within a 1 21 104 cm3 block of pelitic schist were used to document concentric growth zoning of major elements with decreasing mn and ca and increasing fe and mg from cores to rims garnets also preserve growth zoning patterns for hree and mree and show evidence for resorption and partial recrystallization of the outermost rims similar garnet core compositions and identical garnet rim compositions for large like sized porphyroblasts throughout the sample suggest that garnet growth occurred at near equilibrium p t x conditions for major elements over the sample volume comparison of 28 rock sm nd isotope values from the sample indicates substantial cm scale heterogeneity which precludes meaningful use of local garnet rock isotope pairs for isochron age calculation therefore sm nd isotopic compositions of thirty eight concentric core to rim garnet segments from ten large 1 3 cm garnets and two small 1 4 mm bulk garnets with narrow ranges of mn content are paired with sixteen matrix whole rock sm nd isotopic compositions collected over the rock volume to define a range of isochron ages from 383 1 6 8 ma to 324 5 3 3 ma four of the garnets have anomalously young rims that likely result from post growth alteration chlorite quartz and xenotime haloes around garnet suggest that anomalously young garnet rim ages reflect post growth resorption recrystallization effects excluding these young rims yields a range of ages from 383 1 6 8 oldest core to 374 9 1 8 ma youngest rim sm nd age precisions 1 5 m y and high mswd result primarily from isotopic heterogeneity in the finely layered metasedimentary rock matrix however garnet cores with high mn n 7 mantles with intermediate mn n 14 and rims with low mn n 8 including the 2 smaller bulk garnet analyses define three distinct multi grain isochrons of 380 3 2 0 ma n 23 mswd 14 377 3 1 4 ma n 30 mswd 18 and 376 5 1 0 ma n 24 mswd 18 respectively yielding an average garnet growth duration of 3 8 2 2 m y these three composite mn age zones define a mn vs age relationship that reflects depletion of mn in the rock matrix as it is sequestered by growing garnet correlation of garnet major element compositions throughout the sample suggests that major element matrix equilibrium was generally maintained to a first order throughout the ca 4 m y duration of garnet growth

microcracks in ultrabasic rocks under uniaxial compressive stress the initiation and propagation of microcracks under stress are highly dependent upon the mineralogical and textural characteristics of the various lithotypes detailed observation and quantification of microcracks before and after uniaxial compression test were conducted a fresh olivine rich harzburgite and a serpentinized dunite were analyzed collected from the pindos and vourinos ophiolites northern greece respectively in order to compare their microcrack patterns quantitative analysis indicated that during uniaxial compression the intragranular microcracks which are the dominating crack type are gradually transformed or organized into transgranular cracks some of the newly formed transgranular cracks may also be a result of the growth of existing grain boundary cracks the new intragranular microcracks in the olivine rich harzburgite are oriented predominantly parallel to the compressive stress direction while those in the serpentinized dunite show a scattered orientation presumably due to the mesh texture of this rock type the new transgranular cracks of both peridotites tend to be subparallel to the compressive stress direction however many of them show a random orientation due to the fact that they have been formed as a result of the propagation of grain boundary cracks the occurrence of the soft serpentine along fracture surfaces of olivine when it is in assemblage with orthopyroxene tends to absorb the applied stress hampering the development of microcracks in olivine on the other hand in serpentinized peridotites the microcracks are enhanced in olivine because it is surrounded by large amounts of the much softer and flexible serpentine microcracks are usually formed along the cleavage planes of orthopyroxene porphyroclasts indicating that such crystallographic preferred orientations act as planes of weakness controlling the direction of the crack paths cr spinel grains likely comprise locations of initiation of microcracks due to their very hard nature and different mechanical behaviour relative to the surrounding silicate phases knowledge of the mineralogical and textural characteristics may assist in the prediction of potential development of failure surfaces of an ultrabasic rock in service

correlation of mineralogical and textural characteristics with engineering properties of selected granitic rocks from turkey abstract granitic rocks show a variety of engineering properties that may affect quarrying operations tunneling mining slope stability and the use of rock as a construction material the physical and mechanical properties are a function of the mineralogical and textural characteristics of the rock the purpose of this study is to apply correlation analysis to investigate the relationships between petrographical and engineering properties of granitic rocks a variety of granitic rock samples from different parts of turkey were subjected to petrographic studies the same samples were then tested to determine specific gravity dry and saturated unit weight water absorption effective and total porosity sonic velocity schmidt hardness point load strength index uniaxial compressive strength tensile strength and modulus of elasticity the relationships between these properties and the petrographical characteristics are described by simple regression analyses the study revealed that the influence of the textural characteristics on the engineering properties appears to be more important than the mineralogy it also determined that the types of contacts grain mineral shape and size significantly influence the engineering properties of the granitic rocks

assessment of rock geomechanical quality by quantitative rock fabric coefficients limitations and possible source of misinterpretations abstract rock microfabrics were quantified by image measurement system petrographic image analysis of thin sections along with common measured parameters grain area and size length of major and minor axes and their orientation some quantitative parameters aspect ratio grain boundary smoothness and fabric coefficients micropetrographic quality index k texture coefficient tc indexes of interlocking t and grain size homogeneity g were determined the reliability of these parameters for the evaluation of geomechanical properties was tested on the set of granitic rocks showing pronounced variability in rock mechanical properties none of the tested rock fabric coefficients or parameters proved a close correlation to rock mechanical properties except grain size based on experimental findings the grain size is along with porosity the controlling factor of rock mechanical properties of genetically and mineralogically similar rocks obliteration of the real effects of rock fabric parameters on the mechanical properties of rocks by application of complex fabric coefficients disables their practical use in petrography applied to geomechanics

mineralogical controls on the engineering behavior of hydrothermally altered granites under uniaxial compression effective engineering characterization of granites altered through processes of kaolinization is critical for safe extraction and design of slopes for the china clay industry in south west england by considering this important issue representative samples taken from a range of decomposition grades of altered granite were used to assess the controlling influence of changes in mineralogy on uniaxial compressive strength elastic modulus dry density and ultrasonic velocity dramatic reduction in uniaxial compressive strength occurs between alteration grades ii and iii analysis of acoustic emission data constrained by evaluation of scanning electron microscope sem images and strain gauge deformation readings has been used to identify crack propagation stages during uniaxial compression quantitative evaluation of mineralogy was determined from x ray diffraction xrd analysis of representative samples in order to establish relationships between mineralogy such as kaolinite and uniaxial compressive strength for the different alteration grade material the results of the testing confirm that the degree of alteration or kaolinization and associated changes in mineralogy of the granite is directly related to reduction in uniaxial compressive strength and dry density