factors affecting the durability of selected weak and clay bearing rocks from turkey with particular emphasis on the influence of the number of drying and wetting cycles weathering can induce a rapid change of rock material from initial rock like properties to soil like properties the resistance of a rock to short term weathering is described through a durability parameter called the slake durability index as durability is an important engineering parameter particularly for weak and clay bearing rocks it was assessed by a number of tests the main purpose of this study is to assess the influence of the number of drying and wetting cycles and controls of mineralogical composition and strength on durability for this purpose 141 samples of different types of weak and clay bearing rocks were selected from different parts of turkey and relationships between the above mentioned rock characteristics were statistically investigated the samples were subjected to multiple cycle slake durability testing x ray diffraction xrd analysis and uniaxial compression testing in addition to assess the influence of mineralogical composition on durability the mineral contents of the original material and the material passing from the drum of the slake durability apparatus after each cycle were also determined by xrd the results indicate that the type and amount of clay minerals are the main factors influencing the variations of the slake durability index in all samples the durability of the clay bearing rocks studied correlates best with the amount of expandable clay minerals a strong relationship between the uniaxial compressive strength and the fourth cycle slake durability index is found only for the marls among the rock types studied assessment of gradation results of the spoil pile materials consisting of clay bearing rocks also reveals that the increase in percentage of fines in old piles is indicative of material degradation as is evident by multiple cycle slaking it is emphasized that two cycle conventional slake durability testing did not appear to offer an acceptable indication of the durability of weak and clay bearing rocks when compared with multiple cyclic wetting and drying comments on the performance of the test are made that aim to make the testing process and interpretation of the results more reliable

neogene ignimbrites of the nevsehir plateau central turkey stratigraphy distribution and source constraints abstract in anatolia turkey extensive calc alkaline volcanism has developed along discontinuous provinces from neogene to quaternary times as a consequence of plate convergence and continental collision in the nevsehir plateau which is located in the central anatolian volcanic province volcanism consists of numerous monogenetic centres several large stratovolcanoes and an extensive mainly neogene rhyolitic ignimbrite field vent and caldera locations for the neogene ignimbrites were not well known based on previous studies in the neogene ignimbrite sequence of the nevsehir plateau we have identified an old group of ignimbrites kavak ignimbrites followed by five major ignimbrite units zelve sarimaden tepe cemilkoy gordeles kizilkaya and two smaller less extensive ones tahar sofular other ignimbrite units at the margin of the plateau occur as outliers of larger ignimbrites whose main distributions are beyond the plateau excellent exposure and physical continuity of the units over large areas have allowed establishment of the stratigraphic succession of the ignimbrites as from bottom to top kavak zelve sarimaden tepe cemilkoy tahar gordeles sofular kizilkaya our stratigraphic scheme refines previous ones by the identification of the zelve ignimbrite and the correlation of the previously defined akkoy ignimbrite with the sarimaden tepe ignimbrite correlations of distant ignimbrite remnants have been achieved by using a combination a field criteria 1 sedimentological characterisitics 2 phenocryst assemblage 3 pumice vesiculation texture 4 presence and characteristics of associated plinian fallout deposits and 5 lithic types the correlations significantly enlarge the estimates of the original extent and volume of most ignimbrites volumes range between 80 km 3 and 300 km 3 for the major ignimbrites corresponding to 2500 10 000 km 3 in areal extent the major ignimbrites of the nevsehir plateau have an inferred source area in the derinkuyu tectonic basin which extends mainly between nevsehir and the melendiz dag volcanic complex the kavak ignimbrites and the zelve ignimbrite have inferred sources located between nevsehir and derinkuyu coincident with a negative gravity anomaly the younger ignimbrites sarimaden tepe cemilkoy gordeles kizilkaya have inferred sources clustered to the south between the erdas dag and the melendiz dag volcanic complex we found evidence of collapse structures on the northern and southern flanks of the erdas dag volcanic massif and of a large updoming structure in the sahinkalesi tepe massif the present day derinkuyu tectonic basin is mostly covered with quaternary sediments and volcanics the fault system which bounds the basin to the east provides evidence that the ignimbrite volcanism and inferred caldera formation took place in a locally extensional environment while the basin was already subsiding drilling and geophysical prospecting are necessary to decipher in detail the presently unknown internal structure of the basin and the inferred probably coalesced or nested calderas within it

descriptive nomenclature and classification of pyroclastic deposits and fragments recommendations of the iugs subcommission on the systematics of igneous rocks

structural geological problems in gumusler archeological site and monastery there are many underground settlings opened in historical times in cappadocia region and the gumusler monastery is one of these the monastery is a rock monastery church located in approximately 8 km northeast of nigde the most important characteristics of the monastery dated in 11th century ac are that it is an important settlement and touristic area that contains the most preserved frescoes in cappadocia region for this purpose were determined the geological features of the observed units in the areas where the monastery is located and the surroundings were determined engineering geological problems are mentioned for the negative effects of the discontinuities especially in the monastery part during field studies stones with different color and textural characteristics were taken into account and sampling was carried out from four different levels on representative samples laboratory studies were conducted for determining the mineralogical chemical and petrographic and geomechanical properties underground cavities in the region were opened in the lower part of the kizilkaya ignimbrite which has relatively more rock fragments higher amount of rock fragments in the lower part makes this level easier to cave in low welding rate of the rock is believed to be the cause of having relatively low values of engineering properties of the lower levels of examined ignimbrites ignimbrites in these levels are more sensitive against atmospheric conditions than those in the upper levels this study is the first study to determine engineering geology problems in the gumusler archeological area and provide data to planned conservation measures

metamorphism during alpine crustal thickening and extension in central anatolia turkey the nigde metamorphic core complex the nig de massif a metamorphic core complex in central anatolia high temperature reactions can obliterate assemblages turkey contains petrologic evidence for the transition from alpine formed during earlier lower temperature phases of meta crustal thickening to extension and exhumation of high grade mid morphism this can hinder use of petrologic information crustal rocks sillimanite potassium feldspar gneiss formed and to interpret tectonic processes if reaction textures are partially melted during barrovian metamorphism and records max preserved however rocks may record a range of pres imum conditions of 5 6 kbar 700 c the two mica uckapili sure temperature conditions from their prograde and granite and a related dike suite intruded the migmatitic metapelitic or retrograde paths and a more complete picture of the rocks forming a contact aureole that contains andalusite and tectonic evolution of a terrane can be reconstructed of cordierite these low pressure minerals indicate that crustal thick particular interest are the mechanisms and timing of ening was followed by exhumation of mid crustal rocks to relatively transition from contraction to extension and the ac shallow depths 10 km at lower temperatures before the em companying exhumation of middle to lower crustal placement of granitic magma formation of andalusite was followed rocks the present study describes a medium pressure by a second prograde episode of sillimanite growth during low high temperature terrane the nig de massif fig 1 in pressure high temperature metamorphism in the central part of the central anatolia turkey that developed as a meta massif where magmatism was most extensive a generalized p t morphic core complex in response to alpine crustal path for the highest grade rocks therefore consists of an initial thickening metamorphic rocks in the central high grade clockwise path with a late thermal spike and characterizes burial part of the massif record in their mineral assemblages and subsequent exhumation accompanied by magmatism reaction textures and structures the processes of burial exhumation and accompanying magmatism

natural building stones of mexico tenochtitlan their use weathering and rock properties at the templo mayor palace heras soto and the metropolitan cathedral in the aztec period and in colonial times different natural stones originating in the valley of mexico were used for building construction stone weathering was investigated onsite at various historical buildings within the old quarter of mexico city in this study different aspects of weathering and deterioration at three significant historical buildings will be presented the aztec excavation site templo mayor the metropolitan cathedral and the colonial palace of the dukes of heras soto petrophysical properties of the main building stones of these structures were investigated like density porosity pore radii distribution water uptake rate and coefficient thermal and hygric expansion and the mechanical properties of uniaxial compressive strength a relationship between single critical property values according to anisotropy fabric characteristics and specific weathering forms could be deduced

pravcice rock arch bohemian switzerland national park czech republic deterioration due to natural and anthropogenic weathering the dominant factors affecting the development of weathering forms on the pravcice rock arch pra bohemian switzerland national park czech republic are discussed based on the in situ monitoring of weathering forms as well as on laboratory studies of materials taken from this site the in situ monitoring shows the progressive development of distinct weathering forms delamination of case hardened rock surfaces cyclic efflorescence and granular disintegration of exposed weakly cemented rock mass in specific portions of the pra whose location is controlled by lithology jointing local hydrodynamics and exposure to climatic factors from the analysis of efflorescence the dominance of sulphates is evident particularly of gypsum and alums however the synergistic effects of the several salt species that also include minor nitrates and chlorides upon the mechanical disintegration of sandstone can be expected

engineering geological properties and durability assessment of the cappadocian tuff abstract some of the unique landforms the so called fairy chimneys which were formed within the cappadocian tuff of central turkey were used as dwellings in the past and contain culturally valuable wall paintings however these structures are undergoing chemical and physical deterioration due to atmospheric effects for conservation studies an understanding of the engineering geological properties of the tuff is essential in this study emphasis is placed on both material and mass properties of the tuff these properties are evaluated for the assessment of rock durability this study shows that the cappadocian tuff is almost fresh with local discoloration is moderately weak to very weak and has low unit weight very high porosity and high deformability discontinuity surveys revealed two dominant joint sets which not only controlled the formation but also control the structural stability of the fairy chimneys various methods used for the durability assessment of the cappadocian tuff indicate poor to very poor durability due consideration must be given to strength reduction due to moisture poor to very poor durability and the adverse effects of joints on the structural stability of the fairy chimneys

geotechnical and geoenvironmental characteristics of man made underground structures in cappadocia turkey underground cities and semi underground settlements most of which are 1500 years at least exist in the cappadocia region of turkey these man made rock structures are carved in soft tuffs and the best examples of long term performance of man made structures in the field of rock engineering the tuffs also have good thermal isolation properties to be used as housing and storage of foods in this article the authors are only concerned with physical and short term mechanical characteristics due to the wide spectrum of the theme and the in situ characterization of the cappadocia tuffs and the results of investigations are presented in addition a critical overview on possible engineering geological problems at cappadocia with mechanical aspects of historical and modern rock structures and their implications in rock engineering is made from the experimental results in the field it is evident that the engineering characteristics of these rocks do not show significant changes in vertical and horizontal directions however they are prone to atmospheric conditions in addition temperature and humidity measurements at different floors of the underground cities and various parts of semi underground settlements indicated that variations in climatic conditions of the openings are very small when compared to those outside the ground surface

the timing and extent of the eruption of the siberian traps large igneous province implications for the end permian environmental crisis we present new high precision 40ar 39ar ages on feldspar and biotite separates to establish the age duration and extent of the larger siberian traps volcanic province samples include basalts and gabbros from noril sk the lower tunguska area on the siberian craton the taimyr peninsula the kuznetsk basin vorkuta in the polar urals and from chelyabinsk in the southern urals most of the ages except for those from chelyabinsk are indistinguishable from those found at noril sk cessation of activity at noril sk is constrained by a 40ar 39ar age of 250 3 1 1 ma for the uppermost kumginsky suite the new 40ar 39ar data confirm that the bulk of siberian volcanism occurred at 250 ma during a period of less than 2 ma extending over an area of up to 5 million km2 the resolution of the data allows us to confidently conclude that the main stage of volcanism either immediately predates or is synchronous with the end permian mass extinction further strengthening an association between volcanism and the end permian crisis a sanidine age of 249 25 0 14 ma from bed 28 tuff at the global section and stratotype at meishan china allows us to bracket the p tr boundary to 0 58 0 21 myr and enables a direct comparison between the 40ar 39ar age of the traps and the permo triassic boundary section younger ages 243 ma obtained for basalts from chelyabinsk indicate that volcanism in at least the southern part of the province continued into the triassic

field based experimental determination of the weathering rates of the cappadocian tuffs abstract since the last eruption in the cappadocia region that resulted in the formation of irregular hard thick lava layers on top of the cappadocian tuffs atmospheric processes have preferentially sculptured the tuffs the erosion processes have resulted in some beautiful topographical landscape features the so called fairy chimneys however erosion which is an important factor in the formation of fairy chimneys in the early stages has a negative effect on their future over time the number of visitors to this region has also increased and therefore in addition to natural erosion the effects of localized erosion resulting from tourism at the site have increased in the last few decades the physical mineralogical and mechanical properties of the cappadocian tuffs have been widely investigated in previous studies but their weathering characteristics particularly weathering rate were not determined in these studies determination of the weathering rate of these rocks is mandatory especially for conservation projects which should be urgently applied in order to protect this heritage in this study a comprehensive research program was carried out on the weathering properties of the cappadocian tuffs and the weathering rate was determined in field and laboratory investigations to this purpose a detailed field investigation was performed besides field observations the mineralogical physical and mechanical properties of tuffs were also determined in addition to durability evaluation by the slake durability index test wetting drying and freezing thawing tests were also performed for weathering rate assessment of the cappadocian tuffs in order to account for overburden load on some specific parts of pillars these wetting drying and freezing thawing tests were performed under loads the results obtained from field observations of old man made structures and from laboratory studies show that the weathering rate varies between 0 03 and 0 59 mm year for the esbelli tuff and 0 4 and 2 5 mm year for softer part of the kavak member

tectonic controls on metamorphism partial melting and intrusion timing and duration of regional metamorphism and magmatism in the nigde massif turkey protracted heating and melting of orogenic middle crust followed by emplacement of a syn extensional pluton during decompression and cooling are demonstrated for a metamorphic core complex in central turkey new geochronologic data for the nigde massif of the central anatolian crystalline complex document an interval of melting crystallization and pb loss at elevated ambient temperature 85 92 ma determined by u pb shrimp within a single sample of peraluminous granite crustal melting was syn to post peak metamorphism 725 c dated at 91 0 2 0 ma by shrimp analysis of zircon rims in sillimanite schist that is part of the country rock to the pluton metamorphic monazite in sillimanite schist yields a younger age of 84 7 0 7 ma for matrix grains and inclusions in garnet hornblende 40ar 39ar ages from amphibolites interlayered with the sillimanite schists coincide with the timing of emplacement of magma into metamorphic country rock that had experienced cooling and decompression to 12 km and 550 c the similarity of 40ar 39ar ages for biotite in the pluton 79 ma and hornblende 79 81 ma biotite 74 76 ma and muscovite 78 83 ma in the metamorphic country rock document rapid cooling 100 c my following intrusion the coincidence of the youngest u pb magmatic zircon ages and the oldest 40ar 39ar ages combined with structural evidence for normal sense shearing and tectonic unroofing in the late cretaceous suggests that intrusion was driven by extension we propose that crustal melting occurred in the middle crust during prograde metamorphism and or initial decompression and that ascent and emplacement of magma as a pluton were only triggered once extension occurred and removed upper crustal rocks

moisture expansion associated to secondary porosity an example of the loseros tuff of guanajuato mexico the old mining city of guanajuato in middle mexico preserves one of the most important historical legacies in colonial buildings the unesco declared the city world heritage site in 1988 practically all the colonial constructions were built with natural stones from the neighbourhood of which stands a greenish to reddish vulcanite called loseros tuff although the loseros tuff is widely used in historical buildings in the city it shows significant deterioration and weathering effects principally in the parts where the tuff shows a coarse grain size the petrographic petrophysical mineralogical and geochemical properties of the loseros tuff were analysed in order to determine the causes effects behaviour and response to deterioration of this volcanic rock the results of the investigations suggest that in addition to the parameters like the grain size and the porosity properties the pore radii distribution is decisive for the effectiveness of porosity and the water transport into the rock it is recognized that once the liquid water invades the rock the dissolution of the matrix occurs which is accompanied by a sudden moisture expansion favoured by the newly formed secondary porosity and the high content of expandable clay minerals

core complex development in central anatolia turkey tectonic models for the central anatolian segment of the alpine himalayan orogen have not considered this region as part of the aegean extensional province we have found evidence however for oligocene miocene extension and exhumation of midcrustal rocks in a metamorphic dome nigde massif that is structurally and petrologically similar to miocene core complexes 500 km to the west strong correspondence in the timing and kinematic development of the menderes western turkey and nigde core complexes suggests that extensional tectonics and exhumation of mid to lower crustal rocks affected much of the eastern mediterranean region in the nigde massif supracrustal rocks were buried to depths of 16 20 km at high temperatures 700 c during contraction associated with closure of neo tethyan seaways in late mesozoic early cenozoic time following cooling and decompression to 600 c and 10 km metasedimentary rocks underwent a second heating event at low pressures during miocene magmatism that postdated much of the unroofing of the massif development of the nigde core complex was related to exhumation of thickened and thermally weakened continental crust in the upper plate of a north dipping subduction zone the partial subduction of the tauride carbonate platform in the eocene resulted in choking of the subduction zone followed by isostatic rebound and exhumation of the buoyant platform this in turn caused a rapid emergence of the upper plate resulting in erosion of upper crustal rocks and exhumation of midcrustal rocks along the northern edge of the inner tauride suture zone although northern regions of central anatolia contain the same protoliths as the nigde massif and underwent extensive tertiary magmatism they did not undergo similar extension suggesting that core complex development in south central turkey was controlled by the location of thickened and thermally weakened crust adjacent to a suture zone

deformation and metamorphic history of the western blue ridge eastern blue ridge terrane boundary southern appalachian orogen 1 the western eastern blue ridge boundary involved formation by premetamorphic thrusting of an oceanic fragment accretionary wedge island arc upon laurentian basement and metasedimentary cover detailed outcrop scale mapping structural and petrographic analysis reveal both terranes experienced the same deformation at the same metamorphic grade early f1 and f2 isoclinal folds are overprinted by f3 open to tight folds f3 transposes s2 to an axial planar cleavage s3 the youngest penetrative feature prekinematic to synkinematic relative to s2 barrovian metamorphism attained kyanite grade in the western blue ridge wbr upper amphibolite facies in the eastern blue ridge ebr and anatexis in both terranes postkinematic m2b is characterized by appearance of fibrolite throughout the kyanite zone coarsening to granular sillimanite and identification of a kyanite sillimanite isograd in the wbr d3 strain was accommodated by dynamic recrystallization of quartz neocrystallization folding and basal slip of micas pressure solution of plagioclase folding of kyanite and fracturing of garnet scattered lower greenschist facies m4 static retrograde metamorphism resulted in replacement of kyanite and garnet by sericite and chlorite respectively although the juxtaposition of two lithologically distinct terranes implies a fault relationship polymetamorphism and deformation obliterated any microfabrics mineral assemblages or structures that might have developed during premetamorphic thrusting the boundary cannot be an extension of a continent scale dextral strike slip fault system inferred to have developed along laurentian margin in the devonian

metamorphism of the central anatolian crystalline complex turkey influence of orogen normal collision vs wrench dominated tectonics on p t t paths the central anatolian crystalline complex cacc is a microcontinent in the alpine himalayan belt it has previously been considered as a coherent structural entity but although the entire cacc is comprised of similar rocks primarily metasedimentary rocks and granitoids it consists of at least four tectonic blocks characterized by different p t t paths these blocks are the kirsehir north west akdag north east nigde south and aksaray west massifs the northern massifs experienced thrusting and folding during collision and were slowly exhumed by erosion metamorphic rocks are characterized by clockwise p t paths at moderate p t and local low p high t lp ht overprinting in the highest grade rocks apatite fission track ages are eocene to oligocene 47 32 ma the aksaray block represents the hot shallow mid crust of a late cretaceous early tertiary arc it is dominated by intrusions rare metapelitic rocks record low p 4 kbar regional metamorphism overprinted by lp ht contact metamorphism apatite fission track ages are 50 45 ma the nigde massif is different from the other cacc blocks because it evolved as a core complex in a wrench dominated setting it is characterized by clockwise p t paths at moderate p t followed by widespread lp ht metamorphism apatite fission track ages are miocene 12 9 ma significantly younger than those in the northern massifs nigde rocks resided in the mid crust at a time when the rest of the cacc was at or near the earth s surface variations in p t t and tectonic histories especially timing of exhumation between the northern and southern cacc reflect the difference between head on collision vs mid crustal wrenching

gneiss domes metamorphic core complexes and wrench zones thermal and structural evolution of the nigde massif central anatolia 1 the nigde massif a migmatite cored structural dome in south central turkey was metamorphosed deformed intruded and exhumed in an oblique tectonic regime involving a switch from transpression prograde metamorphism to transtension exhumation an 80 ma history of transpression and transtension is recorded in metamorphic rocks of the massif and the last 50 ma are recorded in both basement and overlying basin deposits nigde metamorphic rocks record a high temperature top to north syntranspression ductile fabric that was overprinted by lower grade top to south syntranstension ductile shear zones the 40ar 39ar data for hornblende muscovite and biotite document rapid late cretaceous cooling with the oldest ar hornblende ages 88 79 ma overlapping u pb ages in monazite and zircon 92 78 ma muscovite ar ages are dominantly 81 79 ma suggesting a short time between crystallization of high temperature metamorphic rocks and their cooling biotite ar ages are 79 74 ma with the exception of disturbed samples from the eastern margin of the massif and from eocene granitic stocks in the dome core the eastern margin adjacent to the sinistral central anatolian fault zone records another cycle of burial and exhumation that overprinted earlier fabrics and disturbed isotopic systems these two cycles of burial exhumation took place repeatedly along the same zone this may be characteristic of highly oblique tectonic regimes in the nigde massif burial and exhumation became more localized and of lower amplitude over time suggesting stabilization of the crust

assessment of rock mass strength for underground excavations abstract when the stability of underground openings is assessed one must concern with local and global failure modes local failures may take place as long as rock blocks are kinematically movable into openings while global failure modes are associated with the stress state and the strength of rock mass surrounding openings this fact is always confused in underground rock engineering first the authors briefly describe several approaches how to assess the strength of rock masses together with some new proposals for underground excavations then the estimations by these methods are compared with each other as well as with experimental data finally the validity of these methods are discussed and some recommendations are made for practical applications

correlation of ignimbrites in the central anatolian volcanic province using zircon and plagioclase ages and zircon compositions abstract episodes of high eruptive fluxes 10 3 km 3 year in continental environments are associated with magmatism related to subduction post orogenic collapse intra plate hot spots or rifting during such episodes voluminous ignimbrite deposits are produced which cover landscapes over 10 4 10 5 km 2 in such sequences brief eruptive recurrence and chemical similarity limit the applicability of geochronological and geochemical correlation methods here we present complementary geochronological data 40 ar 39 ar plagioclase eruption and 206 pb 238 u zircon crystallization ages for ignimbrites from the miocene holocene central anatolian volcanic province cavp in addition we successfully employed zircon geochemistry trace elements oxygen isotopes as an alteration resistant indicator to correlate rhyodacitic to rhyolitic ignimbrites whose eruption age differences are too brief to be resolved by 40 ar 39 ar geochronology by applying this method we dismiss previous correlations between stratigraphic members i e sofular and gordeles sofular and sarimadentepe but demonstrate close relationships for other cavp ignimbrites i e kavak units 1 to 4 cemilkoy ignimbrite and overlying fallout deposits our chronostratigraphy reveals two previously unrecognized eruptive pulses at 9 8 ma and 7 5 ma which are characterized by increasing magmatic temperatures 75 100 c within each cycle despite a long term 10 ma eruptive productivity that is about one order of magnitude smaller than in other magmatically active continental plateaus the cavp achieved high eruptive fluxes during brief 1 2 ma intervals

continental arc volcanism and tectonic setting in central anatolia turkey abstract the neogene and quaternary volcanism of central anatolia represents the central sector of the anatolian volcanic arc related to continental collision between the afro arabian and eurasian plates it is closely associated with a complex system of tectonic depressions related to brittle deformations of transtentional type and which commenced in the late miocene the volcanism here considered can be divided into three main periods of activity separated by important deformative and erosive events the first period is represented by a mostly andesitic effusive activity the second period is characterized by the emplacement of a thick ignimbritic sequence and shows an areal distribution up to 11 000 km 2 seven ignimbrite units have been recognized the three main units were found at a distance of more than 100 km from the presumed source area geological and sedimentological data lead us to recognize the melendiz dag volcanic complex and the ciftlik caldera as the probable ignimbrites source vent during the third period great andesitic basaltic stratovolcanoes and a number of prevalently acid monogenic centres developed the relationship between the volcanic activity is clearly conditioned by the main transcurrent fault systems present in central anatolia the neogene quaternary volcanic activity prevalently developed along the ene wsw karaman sivas lineament most of the great central volcanoes developed at the intersection between the ene wsw trends and the ecemis and tuz golu transcurrent faults the structural interpretation of the quaternary monogenic centres is more difficult probably they are related to the very recent n s fault swarms which cross the anatolides and the taurus range