exfoliation microcracks in building granite implications for anisotropy abstract granite is found in many world heritage monuments and cities it continues to be one of the most widely used stones in today s construction given its abundance uniformity and durability quarrymen traditionally cut this rock along its orthogonal slip planes where splitting is easier ranked by ease of splitting these planes are rift grain and hardway granite is traditionally quarried along the rift plane where coplanar exfoliation microcracks coalesce developing a flat surface this splitting surface minimizes the cost and effort of subsequent hewing rift plane was predominantly used on the fair face of ashlars in heritage buildings worldwide determining the petrographic and petrophysical behaviour of these three orthogonal splitting planes in granite is instrumental to understanding decay in ashlars and sculptures the decay of building granite is different in each splitting plane alpedrete granite was the stone selected for this study based on the orientation and distribution of exfoliation microcracks and the characterisation of their implications for the anisotropy of petrophysical properties such as ultrasonic wave propagation capillarity air permeability micro roughness and surface hardness inter and intracrystalline microcrack length and spacing were also measured and quantified the findings show that the splitting planes in alpedrete granite are determined by the orientation of exfoliation microcracks which as a rule are generally straight and intracrystalline and determine the anisotropy of the petrophysical properties analysed splitting planes are the orientation that should be applied when performing laboratory tests for the petrographic and petrophysical properties of building granite

extension crustal structure and magmatism at the outer voring basin norwegian margin regional analysis of new 2d and 3d multichannel seismic data has improved interpretation of the crustal configuration and structural style along the norwegian margin five domains with different structural styles and evolutions are defined along the outer voring basin 1 the nyk high naglfar dome 2 the north gjallar ridge 3 the gleipne saddle 4 the south gjallar ridge 5 the ran ridge early campanian early paleocene and early to mid cretaceous extensional events are evidenced timing of deformation and structural styles observed along each segment reflect a lateral variation of the rifted system probably affected by magma tectonic processes correlation with the deep structures of the outer voring basin shows that the shallow structure in that basin is directly controlled by a deep seated strong high amplitude reflection the t reflection marking the top of a high velocity body v p 7 km s 1 the relation between the lower crustal architecture and the subsurface basin structures has implications for the margin evolution and for the nature of the high velocity body

effects of quarry mining and of other environmental impacts in the mountainous chicam toctina drainage basin cordoba argentina the environmental conditions prevailing in the chicam toctina drainage system approx 138 km2 in cordoba argentina are considered representative of a number of catchments in argentina s sierras pampeanas range two groups of ions reflect the sources of dissolved species in the catchment a a group cl so2 4 and na which recognizes natural and anthropogenic sources and which exhibits significant correlations with n 3 and no 2 and b another group of components ca2 mg2 and hco 3 which is clearly controlled by carbonate rocks and their waste rock products in the headwaters stockpiled marble quarry mining wastes provide a more open system to co2 gaseous exchange than the outcropping rocks thus promoting the increase of carbonate dissolution up to 4 88 g km 2 s 1 during the rainy season this specific yield was 20 higher than the amount estimated for an area with fewer extended mining activities the dissolved load delivered by the upper reaches is subjected in the lower drainage area to various processes mainly controlled by the presence of the city of alta gracia approx 40 000 inhabitants in the dry season due to nutrient inputs supplied by the city photosynthetic activity plays a major role controlling stream ph hence the high values of calcite saturation indexes and the increase of caco3 concentration in bed sediments can be explained by calcite precipitation such a process could be accompanied by the coprecipitation on calcium carbonate of low solubility heavy metal carbonates

detecting the thermal aureole of a magmatic intrusion in immature to mature sediments a case study in the east greenland basin 73 n the cretaceous and triassic argillaceous rocks from the passive margin of greenland have been investigated in order to detect the thermal aureole of magmatic intrusions ranging from metric dyke to kilometric syenite pluton rock eval data tmax generally 0 3 all indicate a maximum of 5km burial for the argillaceous rocks whatever the distance to an intrusion the k ar dating of the clays 2 m fraction suggests that illites are mostly detrital except near magmatic intrusions where younger ages are recorded to get more information about the extent of the thermal aureole rock magnetism data were determined at distance away from the thermal aureole of the syenite intrusion triassic argillaceous rocks reveal a standard magnetic assemblage compatible with their burial r 0 4 percent it is constituted essentially by neoformed stoichiometric magnetite fe o in contrast within the thermal aureole of the magmatic intrusions the cretaceous argillaceous rocks contain micron sized pyrrhotite fe s firmly identified through the recognition of besnus transition at 35k the thermal demagnetization of natural remanence carried by this pyrrhotite shows a diagnostic square shouldered pattern indicating a narrow grain size distribution of pyrrhotite the extension of this diagnostic pyrrhotite maps a 10 km thick aureole around the syenitic pluton away from this aureole the magnetic assemblage is diagnostic of those found in argillaceous rocks where organic matter is mature

the faroe shetland basin a regional perspective from the paleocene to the present day and its relationship to the opening of the north atlantic ocean the faroe shetland basin is located offshore nw scotland on the se margin of the atlantic ocean and comprises numerous sub basins and intra basin highs that are host to a number of significant hydrocarbon discoveries the principal hydrocarbon discoveries are in palaeocene eocene strata though earlier ones are known and therefore their existence is intimately linked to the opening and evolution of the north atlantic from 54 ma the final rifting and separation of greenland from eurasia is commonly attributed to the arrival of a mantle plume which impacted beneath greenland in the early tertiary moreover the ensuing plate separation is commonly described in terms of instantaneous unzipping of the north atlantic whereas in reality proto plate boundaries were more diffuse during their inception and the linked rift system including connections with the arctic which we see today was not established until late palaeogene early neogene time from a regional analysis of ocean basin development including the stratigraphic record on the adjacent continental margins the significance of the greenland iceland faroe ridge and the age and role of iceland we propose a dual rift model whereby north atlantic breakup was only partial until the oligo miocene with true final breakup only being achieved when the reykjanes and kolbeinsey ridges became linked as final breakup coincides with the appearance of iceland this model negates the need for a plume to develop the north atlantic with rifting reliant on purely plate tectonic mechanisms lithospheric thinning and variable decompressive upper mantle melt along the rifts

mapping and facies analysis of paleocene mid eocene seismic sequences offshore southern west greenland abstract new interpretations are reported of the sedimentology and sequence stratigraphy of the palaeogene sediments encountered by the boreholes hellefisk 1 ikermiut 1 kang miut 1 nukik 1 and nukik 2 offshore southern west greenland these interpretations together with new biostratigraphic and palaeoenvironmental interpretations have been used to correlate the boreholes and to calibrate seismic sequences interpreted on a grid of reflection seismic data the interpreted seismic sequences lie between major regional unconformities of danian and mid eocene age the new interpretations show that the area offshore southern west greenland was subject to major uplift and erosion during the danian when latest cretaceous sediments were removed sedimentation restarted in the late danian coevally with major volcanism in central west greenland and the start of sea floor spreading in the labrador sea late paleocene sediments were deposited in a predominantly extensional tectonic environment the extensional stresses continued in most areas during the early eocene but in the northern and northwestern part of the basins a transtensional system developed along the strike slip faults that transferred sea floor spreading movements between the labrador sea and baffin bay sediment input to the basins was predominantly from the north possibly from a major river system flowing out of central greenland lesser amounts of sediment came from the east from the mainland of greenland and minor amounts from the west the thickness of total sediment decreases substantially from north to south the sediments were deposited in environments that ranged from fresh water marginal marine to upper bathyal proximal environments are probably generally sand prone but distal environments probably contain larger amounts of mud some of which could contain a mature source rock for oil basin floor fans syn tectonic wedges and turbidite channel complexes that could act as hydrocarbon reservoirs sealed by surrounding muds have been identified in many of the seismic sequences

continental flood basalts episodic magmatism above long lived hotspots abstract the eruption of continental flood basalt cfb may reflect episodic magmatism above long lived mantle plumes the iceland and yellowstone hotspots have generated successive cfb provinces large intrusive complexes anomalous uplift basin formation and rifting events and linear volcanic chains dating back 120 and 70 ma respectively amagmatic intervals occurred 1 when ascent of plumes to shallow levels was impeded by impenetrable lithosphere resulting in sub lithospheric ponding of plume mantle and 2 in response to dispersion by subducting oceanic lithosphere in convergent margin settings by comparison with the plume eruptive potential of typical oceanic hotspots it is apparent that preservation of only a small portion of plume mantle ponded during an amagmatic interval is necessary to account for large volume of cfbs thermal erosion lithospheric attenuation translation of ponded hotspot mantle to the base of thinner penetrable lithosphere and passage of plume mantle through slab windows in subducting oceanic lithosphere led to subsequent breakthrough and eruption of cfb since both mantle plume and plate tectonic processes have been operating since the archean it seems likely that the migration of continents over hotspots with attendant magmatic and tectonic consequences is a common occurrence in the geological record

granitic dimensional stones in uruguay evaluation and assessment of potential resources in uruguay commercial granite varieties comprise mafic rocks granitoids and syenitoids there is a long tradition in uruguay as well as worldwide of using dimensional stones in architecture and art specially granitic ones some of the present applications of these dimensional stones are as facade cladding countertops and outdoor and indoor floor slabs the color spectrum of the uruguayan granitic dimensional stones varies from black to light gray covering a wide variety of red and pink and minor greenish gray the decor of these granitic dimensional stones is mainly determined by their fabric fundamentally the grain size and the color distribution between the different minerals that compose the rocks in the present research the most important commercial granites were sampled to analyze their petrography and petrophysical properties a detailed structural analysis has been performed in several deposits as well as the application of the software 3d block expert for modeling the possible raw block size distribution other factors controlling the mining viability of the deposits were also studied e g homogeneity heterogeneity of color and decor and the possible reserves were calculated

exploration for dimensional stone implications and examples from the precambrian of southern finland dimension stone is a natural rock that must fulfil high qualitative standards defined by both geology based factors and non geological factors the stone itself appearance soundness and the market demand are the two most important aspects in the quality assessment the process of geological dimension stone exploration is a systematic and stepwise procedure including individual steps of desk study field mapping detailed examination geo radar survey and core drilling the location of all economically feasible dimension stone deposits is strictly controlled by geological factors knowledge of these factors is fundamental in identifying new sites with potential for dimension stone in this work the geological constraint on the occurrence of dimension stone in three areas in the precambrian of southern finland has been investigated the deposits are localized to part of an area in which different geological features in combination have produced rock of good dimension stone quality the study shows that for example vertical movements in the crust magmatic evolution of an intrusion and metamorphic grade define the location of rocks suitable for dimension stone

influence of fracture system on the exploitation of building stones the case of the mondim de basto granite north portugal the most negative aspects in the exploitation of weathered granites as ornamental stones tend to be heterogenic coloration and fracturing therefore an accurate study is needed for a comprehensive evaluation of the granite resources during an exploration campaign this paper presents the results of the fracturing evaluation of a region located in north of portugal where the mondim de basto granite a stone with a high weathering degree is exploited the regional fracturing was evaluated from lineaments in aerial photos and then compared with local jointing in quarries the jointing in each quarry is characterized according to the strike and dip joint spacing and volumetric joint count two indices were proposed to facilitate the jointing comparison among quarries the joint space length ljs and joint set spacing sjs ljs is based on the sum of all the spacing values obtained perpendicularly to the strike direction sjs is computed based on the overall mean median spacing and on the number of joint sets observed in each quarry the most important joint sets in the subdivision of the rock mass were found not to be in accordance with the regional fracturing patterns highlighting the necessity of studying the fracturing at all scales

a plume model of transient diachronous uplift at the earth s surface convection in the earth s mantle appears to be strongly time dependent on geological time scales however we lack direct observations which would help constrain the temporal variation of convection on timescales of 1 10 ma recently it has been demonstrated that transient uplift events punctuated the otherwise uniform thermal subsidence of sedimentary basins which fringe the icelandic plume in the faroeshetland basin three dimensional seismic reflection surveys calibrated by well logs have been used to reconstruct a 55 million year old transient event the minimum amount of uplift is 490 m which grew and decayed within 2 ma this event has also been mapped 400 km further east in the north sea basin where peak uplift with an amplitude of 300 m occurred 0 3 1 6 ma later neither observation can be explained by glacio eustatic sea level changes or by crustal shortening we describe a simple fluid dynamical model which accounts for these transient and diachronous observations in this model we assume that the icelandic plume was already in existence and that it had an axisymmetric geometry in which hot e g 1400 c asthenospheric material flows away from a central conduit within a horizontal layer a transient temperature anomaly introduced at the plume center flows outward as an expanding annulus its geometry is calculated using radial flow between two parallel plates with a poiseuille cross stream velocity profile the expanding annulus of hot asthenosphere generates transient isostatic uplift at the earth s surface stratigraphic observations from both basins can be accounted for using a plume flux of 1 3 10 8 km 3 ma 1 for a layer thickness of 100 km plume flux is broadly consistent with that required to account for neogene 0 20 ma v shaped ridges south of iceland although our transient temperature anomalies are larger we suspect that the stratigraphic expression of transient convective behaviour is common and that a careful examination of appropriate records could yield important insights

evaluation of weathering resistance classes in clastic rocks on the example of polish sandstones the scope of the paper is an attempt at the identification of the weathering resistance classes within clastic rocks by means of analysis of capillary pressure saturation curves the porosimetric parameters corresponding to the cementing character and the grains mineralogical content are very important features of stone building materials because of the weathering processes the analysed rocks were polish sandstones and muddy sandstones used for building purposes collected from different geological units of poland i e sudety mts carpathian mts and holy cross mts the results indicate the usefulness of sandstone materials for building purposes they could also be used in conservation procedures and for the reconstruction of existing buildings and monuments basing on the parameterisation with the van genuchten function of cumulative capillary pressure saturation curves it was possible to distinguish four groups of the sampled rocks the lithological features and weathering sustainability within the groups are quite uniform what allow identifying the weathering resistance classes taking into account the complicated nature of all the factors influencing weathering processes it is supposed that the presented parameterisation could be a useful tool for weathering resistance classification of clastic rocks the classification could be useful in building industry and in conservation of historical stone monuments

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

basin seismic stratigraphy and aspects of prospectivity in the ne baffin bay northwest greenland abstract subsurface mapping in the northeastern part of baffin bay offshore northwest greenland indicates the presence of large basement structures and sedimentary basins we identify eight seismic stratigraphic units that can be genetically related to the regional geology and tectonic development the seismic interpretation includes the top of paleocene to eocene volcanic rocks which cover most parts of the southern and western study area using this horizon as a time marker the seismic units are divided into pre cenozoic and palaeogene to neogene strata based on comparison to equivalent units exposed onshore west greenland and canada and sampled by exploration wells farther south in the disko west offshore nuuk region our interpretation of the faults and tectonic elements suggest that the main extensional faults and basin formation took place mainly during the cretaceous and into the paleocene subsequent compressional tectonics and inversion were accompanied by strike slip faulting and local transtensional faults and flexures this last phase of deformation corresponds to the well documented eurekan orogeny in ellesmere island and northern greenland that developed as a result of northward motion and possible counterclockwise rotation of greenland relative to the north american plate we surmise that these tectonic phases exerted a strong control on basin infill by activation of hinterland sediment sources during cretaceous and palaeogene times the deep basins may include cretaceous and palaeogene organic rich sediments with hydrocarbon source potential we estimate that maturation could have started during the eocene

decision criteria for the exploration of ornamental stone deposits application to the marbles of the portuguese estremoz anticline abstract ornamental stones are almost ready made raw materials with a high economic value for the building construction industry the discovery of new near surface deposits the very low exploitation efficiency the huge amounts of wastes produced and the land use accessibility conditions are the main challenges that the extractive industry for this mineral resource is facing nowadays research on advanced geological exploration tools and methodologies is needed to reply to those challenges during the process of geological ornamental stone deposits exploration the unique and decisive criteria that should be considered are its dimensions homogeneity and fracturing state lithostructural geological mapping and in situ fracturing surveys are the basic indispensable tools for their field assessment by applying these criteria and tools to a marble rich area in the portuguese estremoz anticline and a step by step numerical evaluation of the qualitative geological parameters the delimitation of the best target areas for exploitation or environmental rehabilitation has been effectively mapped

southeast baffin volcanic margin and the north american greenland plate separation plate breakup over plumes is characterized by the development of margins showing extensive magma production both underplated at moho level and extruded as thick piles of seaward dipping lava formations the disko svartenhuk area in west greenland is one of the few places in the world with exposed seaward dipping basalts forming a prism whose thickness increases seaward we present a quantitative tectonic study of this margin which we tentatively restored in its geodynamic position during the different stages of plate separation between greenland and north america our structural data are constrained with recently published 39ar 40ar and new and coherent 40k 40ar geochronology in dikes of different orientations the first order structure is that of a tectonically driven seaward crustal flexure linked to definitive plate breakup between greenland and baffin island during the eocene coeval with the formation of the upper part of the exposed seaward dipping volcanic prism this flexing is associated with a significant crustal stretching associated with arrays of continentward dipping normal faults this across strike structure is correlated to a fundamental along strike segmentation with the three segments adopting a zigzag strike there is a clear increase of extensional strain at the extremities of the segments eocene extension trended n060 on average in the northern and southern segments but was nw trending in the central ne trending nugssuaq segment we discuss the interpretation of such an extension perpendicular to the different margin segments from a regional point of view the n060 extension is distinct in orientation from the approximately n s trend of plate separation between north america and greenland in the baffin bay during the eocene however the extension recorded in the margin is nearly perpendicular to the obliquely spreading eocene accretion axis in the baffin bay this latter point suggests a mantle or ridge control of the development of the margin over regional far field lithospheric stress models

sedimentation and lithofacies paleogeography in southwestern china before and after the emeishan flood volcanism new insights into surface response to mantle plume activity abstract investigations into permian sedimentation and reconstruction of paleogeography in sw china are aimed at characterizing sedimentary responses to the emeishan mantle plume in addition to erosional features on the sediments underlying the uplifted emeishan basalts unusual depositions of permian age are also present in the emeishan large igneous province lip specifically carbonate gravity flows and submarine incised canyon fillings were developed in the western margin of the postulated uplifted area and rifting trenches were developed along the eastern margin alluvial fan deposits occur at the boundary between the inner and intermediate zones these depositions all rest on the maokou formation and are in turn covered by the emeishan basalts implying synchronism between crustal uplift and depositional events these deposits and the associated extension and normal faulting along the margin of and within the lip represent sedimentary features resulting from dynamic behavior of mantle plume com

sedimentary evidence for a rapid kilometer scale crustal doming prior to the eruption of the emeishan flood basalts biostratigraphic and sedimentologic investigations in 67 sections have been carried out for the middle permian maokou formation that immediately underlies the emeishan flood basalts in southwest china the results suggest a domal crustal thinning before the emplacement of the emeishan large igneous province variably thinned carbonates in the maokou formation are capped by a subaerial unconformity which is generally manifested by karst paleotopography paleoweathering zone or locally by relict gravels and basal conglomerates provenance analysis indicates that these gravels and conglomerates were mainly derived from the uppermost maokou formation therefore the stratigraphic thinning likely resulted from differential erosion due to regional uplift iso thickness contours of the maokou formation delineate a subcircular uplifted area in accordance with the crustal doming caused by a starting mantle plume as predicted by experimental and numerical modeling the duration of this uplift is estimated to be less than 3 myr and the magnitude of uplift is greater than 1000 m the sedimentary records therefore provide independent supporting evidence for the mantle plume initiation model for the generation of the emeishan flood basalts

black dimensional stones geology technical properties and deposit characterization of the dolerites from uruguay dimensional stones with a black color occupy a prominent place on the international market uruguayan dolerite dikes of andesitic and andesitic basaltic compo sition are mined for commercial blocks of black dimen sional stones a total of 16 dikes of both compositions were studied and samples collected for geochemical and petro graphical analysis color measurements were performed on different black dimensional stones in order to compare them with the uruguayan dolerites samples of the two commercial varieties absolute black and moderate black were obtained for petrophysical analysis e g density porosity uniaxial compressive strength tensile strength etc detailed structural analyses were performed in sev eral quarries geochemistry and petrography determines the intensity of the black color the uruguayan dolerite absolute black is the darkest black dimensional stone analyzed in this study the petrophysical properties of uruguayan dolerites make them one of the highest quality black dimensional stones structural analyses show that five joint sets have been recognized two sub vertical joints one horizontal and two diagonal these joint sets are one of the most important factors that control the deposits since they control the block size distribution and the amount of waste material

sediment supply on the west greenland passive margin redirection of a large pre glacial drainage system the mesozoic cenozoic separation of greenland and north america produced the small oceanic basins of the labrador sea and baffin bay connected via a complex transform system through the davis strait during rifting and partial breakup sedimentary basins formed that record the changing regional sediment supply the onshore and offshore stratigraphy of central west greenland outlines the presence of a major fluvial system that existed during the cretaceous and was later redirected in the early cenozoic by the formation of the west greenland igneous province hydrological analysis of greenland9s isostatically balanced basement topography outlines two major drainage systems that likely flowed across greenland prior to the onset of glaciation and emptied into the sisimiut basin within the davis strait offshore west greenland the course of the northern drainage system suggests that it initially flowed nw into the cretaceous palaeocene nuussuaq basin before being redirected sw around the west greenland igneous province in the mid palaeocene moreover characteristics of these two drainage systems suggest they acted as a single larger fluvial system prior to the onset of glaciation that was likely the primary source of sediment across central west greenland throughout the cretaceous and palaeogene this scenario provides a greater understanding of the west greenland margin9s late cenozoic evolution which differs from previous interpretations that hypothesize a period of considerable post rift tectonism and uplift this work highlights the importance of large pre glacial drainage systems across north atlantic passive margins and their relevance when studying post rift stratigraphy in rifted margin settings supplementary material isostatic modelling hydrological analysis and chi mapping is available at https doi org 10 6084 m9 figshare c 5050146

the temporal relationship between joints and faults abstract examples are presented of three temporal relationships between joints and faults joints that pre date faults joints that are precursors to or synchronous with faults and joints that post date faults emphasis is placed on strike slip faults in carbonate beds but other examples are used general rules are given for identifying the three temporal relationships between joints and faults joints that formed before faults can be dilated sheared or affected by pressure solution during faulting depending on their orientation in relation to the applied stress system faulted joints can preserve some original geometry of a joint pattern with pinnate joints or veins commonly developing where faulted joints interact joints formed synchronously with faults reflect the same stress system that caused the faulting and tend to increase in frequency toward faults in contrast joints that pre or post date faults tend not to increase in frequency towards the fault joints that post date a fault may cut across or abut the fault and fault related veins without being displaced by the fault they may also lack dilation near the fault even if the fault has associated veins joints formed either syn or post faulting may curve into the fault indicating stress perturbation around the fault different joint patterns may exist across the fault because of mechanical variations geometric features may therefore be used in the field to identify the temporal relationships between faults and joints especially where early joints affect or control fault development or where the distribution of late joints are influenced by faults

cenozoic uplift and subsidence in the north atlantic region geological evidence revisited abstract the topographic evolution of the passive margins of the north atlantic during the last 65 myr is the subject of extensive debate due to inherent limitations of the geological geomorphological and geophysical methods used for studies of uplift and subsidence we have compiled a database of sign time and amplitude where possible of topographic changes in the north atlantic region during the cenozoic 65 0 ma our compilation is based on published results from reflection seismic studies aft apatite fission track studies vr vitrinite reflectance trends maximum burial sediment supply studies mass balance calculations and extrapolation of seismic profiles to onshore geomorphological features the integration of about 200 published results reveal a clear pattern of topographic changes in the north atlantic region during the cenozoic 1 the first major phase of cenozoic regional uplift occurred in the late palaeocene early eocene ca 60 50 ma probably related to the break up of the north atlantic between europe and greenland as indicated by the northward propagation of uplift it was preceded by middle palaeocene uplift and over deepening of some basins of the north sea and the surrounding areas 2 a regional increase in subsidence in the offshore marginal areas of norway the northern north sea the northern british isles and west greenland took place in the eocene ca 57 35 ma 3 the oligocene and miocene 35 5 ma were characterized by regional tectonic quiescence with only localised uplift probably related to changes in plate dynamics 4 the second major phase of regional uplift that affected all marginal areas of the north atlantic occurred in the plio pleistocene 5 0 ma its amplitude was enhanced by erosion driven glacio isostatic compensation despite inconclusive evidence this phase is likely to be ongoing at present

possible correlation between a mantle plume and the evolution of paleo tethys jinshajiang ocean evidence from a volcanic rifted margin in the xiaru tuoding area yunnan sw china abstract several paleozoic sutures in southwestern china provide a record of the history of the paleo tethys ocean whose birth and final closure are associated with the breakup and assembly of gondwanaland recent studies indicate that there are widespread oib type mafic volcanic rocks within these suture zones and intervening terranes this paper examines the geology and geochemistry of volcanic rocks in the xiaruo tuoding area a remnant passive margin succession of the jinshajiang paleo tethyan ocean the sedimentary and volcanic stratigraphy of this area is interpreted as a seaward dipping margin with a few continentward dipping normal faults the available geochemistry of these volcanic rocks suggest that they are oib like basalts characterised by sio 2 42 78 50 46 wt high tio 2 contents tio 2 2 2 3 55 wt moderate mgo 4 15 6 49 wt mg 0 37 0 50 high ti y ratios mostly 450 large ion lithosphere elements enrichment high strength field elements and rare earth elements with la nb 1 04 1 39 ce yb 18 38 30 sm yb 2 16 3 52 87 sr 86 sr i 0 705350 0 707867 and nd t 1 43 1 90 these geochemical and isotopic signatures are generally similar to those of the emeishan flood basalts which together with stratigraphic constraints demonstrate that these volcanics were formed in a volcanic rifted margin probably associated with a mantle plume a new model is proposed to interpret the evolution of the jinshajiang paleo tethyan ocean and its possible relationship to the emeishan mantle plume in this model we argue that the opening of the jinshajiang paleo tethyan ocean in the carboniferous was caused by a mantle plume the mantle plume was active to the east along the western margin of the yangtze craton between 300 and 260 ma from which the voluminous emeishan flood basalts were erupted at 260 ma the closure of the jinshajiang ocean occurred since the middle permian continuous westward subduction generated the jiangda weixi magmatic arc to the west of the jinshajiang suture this subduction also partly destroyed and or tectonically sliced the volcanic rifted margin some seaward dipping volcanic sedimentary sequences on the east flank of the jinshajiang ocean were preserved but are strongly deformed

granite tectonics revisited insights from comparison of k feldspar shape fabric anisotropy of magnetic susceptibility ams and brittle fractures in the jizera granite bohemian massif in the jizera granite of the krkonose jizera plutonic complex northern bohemian massif contrasting patterns of magmatic k feldspar fabrics and brittle fractures characterize different structural levels of the pluton the uppermost exposed level at 800 1 100 m above sea level is dominated by flat foliation that overprints two steep foliations in contrast k feldspar shape fabric in an underground tunnel 660 m above sea level shows complex variations in orientation and intensity magnetic fabric carried by coaxial contributions of biotite magnetite and maghemite is homogeneous along the examined section of the tunnel and is decoupled from the k feldspar fabric the jizera granite is crosscut by two regional sets of subvertical fractures ne sw and nw se and by near surface exfoliation joints the multiple fabrics are inferred to reflect a complex magmatic strain history at different structural levels of the pluton bearing little or no relationship to the fracture network in contrast to the original concept of hans cloos granite tectonics we conclude that no simple genetic relationship exists between fabrics and fractures in plutons an alternative classification of fractures in plutons thus should avoid relationships to magmatic fabrics and should instead consist of cooling syntectonic uplift and post uplift fractures

limestones under salt decay tests assessment of pore network dependent durability predictors three portuguese limestones two grainstones semi rijo and moca creme commercial types and a travertine were subjected to salt crystallisation test en 12370 1999 grainstones specimens showed higher weight loss than the travertine ones results are discussed using parametric and nonparametric statistics in relation to pore space characteristics that have been considered durability predictors evaluated at the macroscopic water imbibition and microscopic mercury injection porosimetry levels several of the pore space parameters indicate differences between grainstones and travertine but these differences are much lower than the differences in weight loss results of the durability dimensional estimator dde seem to present a discrepancy with higher values in the rock type having lower weight loss travertine additionally weathering patterns of travertine samples show marked irregularities a feature that is not assessed by weight loss these irregularities are attributed to heterogeneous spatial distribution of detritic components a feature that is not assessed by pore space parameters comparing the grainstones moca creme showed higher values of mass loss and several durability predictors suggested noteworthy differences in relation to semi rijo however these differences are much lower than differences in weight loss calculated crystallisation pressures are even higher for semi rijo it is proposed that petrographical aspects of moca creme namely heterogeneity related to the presence of bioclasts and veinlets could contribute to explain the higher weathering susceptibility of this rock type these results highlight the need to include petrographical features in assessments of durability and the usefulness of visual description on the characterization of salt weathering

characterization and quality assessment of granitic building stone deposits a case study of two different portuguese granites abstract several factors determine building stone exploration in order to maximize the extraction processing and application of these natural materials some factors are intrinsic to stones such as their physical mechanical properties while others are related to their exploitability such as quarry reserves or fracturing density during an exploration campaign these factors are not always considered or properly weighed in terms of the negative consequences on quarry activities or rock behaviour under particular conditions in this study two well known portuguese granites are assessed to highlight the main factors these granites have different characteristics weathered and sound and are exploited in quarries with different joint densities the most relevant physical mechanical properties were evaluated and related to the specific petrophysical features of each granite the fracture patterns were identified in the quarries and then modelled in order to compute the quarry yield the weathered granite shows an important microcrack network and a general alteration of the rock forming minerals which has an important impact on its physical mechanical properties and on the resistance to environmental factors moreover the extreme differences in the degree of weathering require careful choices for the possible applications in both quarries the joint sets are similar to the regional faulting but some random joints can be found and consequently diminish the quarry yield the development of horizontal sheet joints during the exploitation process could have a great influence on the quarry productivity if they are not used do delimitate the extracted blocks the modelling of the natural fracture pattern allows us to determine the potential volume of blocks that could be exploited however the quality of the information gathered could lead to an over estimation of the quarry production this example shows the importance of the exhaustive researches during a building stone assessment campaign

regional uplift associated with continental large igneous provinces the roles of mantle plumes and the lithosphere the timing and duration of surface uplift associated with large igneous provinces provide important constraints on mantle convection processes here we review geological indicators of surface uplift associated with five continent based magmatic provinces emeishan traps 260 million years ago ma siberian traps 251 ma deccan traps 65 ma north atlantic phase 1 61 ma and phase 2 55 ma and yellowstone 16 ma to recent all five magmatic provinces were associated with surface uplift surface uplift can be measured directly from sedimentary indicators of sea level in the north atlantic and from geomorpholocial indicators of relative uplift and tilting in yellowstone in the other provinces surface uplift is inferred from the record of erosion in the deccan north atlantic and emeishan provinces transient uplift that results from variations in thermal structure of the lithosphere and underlying mantle can be distinguished from permanent uplift that results from the extraction and emplacement of magma transient surface uplift is more useful in constraining mantle convection since models of melt generation and emplacement are not required for its interpretation observations of the spatial and temporal relationships between surface uplift rifting and magmatism are also important in constraining models of lip formation onset of surface uplift preceded magmatism in all five of the provinces biostratigraphic constraints on timing of uplift and erosion are best for the north atlantic and emeishan provinces where the time interval between significant uplift and first magmatism is less than 1 million years and 2 5 million years respectively rifting post dates the earliest magmatism in the case of the north atlantic phase 1 and possibly in the case of siberia the relative age of onset of offshore rifting is not well constrained for the deccan and the importance of rifting in controlling magmatism is disputed in the emeishan and yellowstone provinces in these examples rifting is not a requirement for onset of lip magmatism but melting rates are significantly increased when rifting occurs models that attempt to explain emplacement of these five lips without hot mantle supplied by mantle plumes often have difficulties in explaining the observations of surface uplift rifting and magmatism for example small scale convection related to craton or rift boundaries edge driven convection cannot easily explain widespread 1000 km scale transient surface uplift emeishan deccan north atlantic and upper mantle convection initiated by differential incubation beneath cratons the hotcell

late carboniferous crustal uplift of the tarim plate and its constraints on the evolution of the early permian tarim large igneous province abstract the early permian tarim large igneous province lip in northwestern china has been related to a mantle plume mostly constrained by petrology and geochemistry however the crustal uplift erosion related to a mantle plume has rarely been addressed in order to improve our understanding of crustal uplift erosion we have studied the stratigraphy and sedimentology of eighty five boreholes outcrops and two seismic profiles the results indicate a regional unconformity and onlap contact between the earliest permian and carboniferous strata with denudation of carboniferous and deposition of earliest permian strata the denudation of carboniferous strata has been divided into three types of erosion deep partial and weak with a deep erosion zone located in northern tarim region east of keping and west of northern tarim which gradually weakens towards the south above the unconformity the early permian pre eruption deposit is thinnest 300 m which is consistent with the spatial distribution of late carboniferous erosion this unconformity represents a spatial distribution of denudation forced by doming uplift erosion at the end of the carboniferous with minimum estimation of its vertical and lateral extent of 887 m and 300 km respectively which are comparable to those of other mantle plume generated lips both the late carboniferous erosion and early permian sedimentary records indicate a crustal uplift event at 300 ma the uplift was short term and approximately dome shaped occurring immediately before the tarim lip 290 ma these results provide new stratigraphic and sedimentological constraints on the role of a mantle plume in the formation early permian tarim lip from a crustal uplift perspective the spatial distribution of denudation suggests that the regions of northern tarim or further north represent the centre of the potential plume head

characterizing block geometry in jointed rockmasses the intersection of discontinuities in a jointed rockmass creates in situ blocks of variable three dimensional 3d geometry the size and shape of rock blocks in a rockmass assembly have a dominant influence on the engineering properties of a rockmass and control for example the failure geometry of a rock face and the optimum associated support and surface restraint strategy the distribution of block volumes within a rockmass can be effectively analyzed and communicated using a cumulative volume distribution curve integrated with this analysis a methodology has been developed to characterize the shape and volumetric shape distribution of rock blocks in 3d models of jointed rockmasses the proposed block shape characterization method takes into account two factors the first describes the shortening of the minor principal axis of the block while describes the elongation of the major axis when merged with the block volume distribution the block shape characterization method can effectively describe and classify both the size and shape distributions of any jointed rockmass and is not limited to orthogonal blocks or hexahedra this methodology can classify any polyhedra and has been developed and calibrated based on synthetic joint data and simulated block assemblies a demonstration is given of its effectiveness in characterizing block geometries in the field using mapped fracture data

granite fracture index to check suitability of granite outcrops for quarrying a correct knowledge of fracture patterns previous to quarrying is important for economical exploitation this work comprises the general characterization of the discontinuities of 10 granite rock masses in ne portugal during the study some discontinuity characteristics such as orientation persistence aperture trace length and spacing were evaluated the differences in the characteristics of the selected granites were described and the most important exploration factors were identified in the granites studied most of the joints are oriented from n10 e to n50 e which is compatible with the regional fracture pattern concerning joint termination the xx type is common while the rr type is rare the persistence index ranges from 3 5 to 25 4 closed joints are predominant in the granites studied n 72 4 and openings of the others are about 1 2 mm as a result of superficial displacement of the granite blocks the percentage of filled joints usually by quartz and pegmatite is different from one granite to another but most are b 20 the average joint length ranges from 11 1 m in post tectonics granites to 4 6 m in syntectonic granites joint spacing varies from 0 98 to 2 8 m with higher values in post tectonic granites joint space distributions of the granites studied are close to log normal and exponential distributions volumetric joint count jv ranges from 0 8 to 2 1 joints m 3 and is used for categorizing the places of each granite the relationships between jv and other joint characteristics such as length spacing and number of joint sets were investigated a granite fracturing index gfi is introduced computed on the basis of volumetric joint count number of joint sets and true joint spacing the gfi classification of studied places allows us evaluate the suitability for profitable exploitation 2007 elsevier b v all rights reserved

role of subaerial volcanic rocks and mantle plumes in creation of south atlantic margins implications for salt tectonics and source rocks abstract seaward dipping reflectors sdrs represent flood basalts rapidly extruded during either rifting or initially subaerial sea floor spreading evaporites can form on this basaltic proto oceanic crust as in the afar triangle today evidence for sdrs in south atlantic deep water regions comes from proximity to the uniquely large parana etendeka volcanic province onshore the tristan and gough hot spots drilled volcanic rocks and seismic profiles showing sdr provinces more than 100 km wide as much as 7 km thick and thousands of kilometers long sdrs are clearest adjoining the aptian salt basins however we speculate that sdrs are also present but seismically obscured below the salt basins we argue that the conjugate aptian salt basins are post breakup not pre breakup they were separated from the start by a mid oceanic ridge distal salt accumulated on proto oceanic crust not rift basins this hypothesis is supported by seismic stratigraphy and structure magnetic anomalies plate reconstructions and hydrothermal potash evaporites an important implication for exploration is that thick basalts rather than rift age source rocks may underlie distal parts of the salt basins

block geometry and rockmass characterization for prediction of dilution potential into sub level cave mine voids when sub level caving is used as an underground mining method for the exploitation of diamondiferous kimberlite pipes a deep steep sided pipe is created that is susceptible to sloughage pipe wall sloughage allows waste rock to mix with and dilute the caved kimberlite ore using the koala kimberlite pipe at ekati diamond mine as a case study a method has been developed using rockmass and rock structure characterization integrated with discrete block dem simulation for comparative assessment of dilution potential and the classification and mapping of dilution source zones around the kimberlite pipe the assessment process involves the development of a geomechanical model to delineate the structural fabric within the host rockmass and characterize the size and shape distributions of discrete rock blocks defined by intersecting discontinuities combining the slope geometry with the structural geology model allows for a zone by zone numerical analysis of pipe wall stability under gravitational loading a final dilution map is developed in order to target problem areas where the highest levels of slope instability are anticipated

optimized extraction of dimension stone blocks the profitable production of dimension stone mainly depends on the extractable block size the regularity and volume of the blocks are of critical importance and are controlled by the three dimensional pattern of the discontinuity system therefore optimization of block size has to be the aim when quarrying for natural stone this is mainly connected to the quantification of joints and fractures i e their spacing and orientation the problem of finding unfractured blocks within arbitrarily oriented and distributed planes can be solved effectively by a numerical algorithm the main effects of joint orientations on block sizes and shapes will be presented in this article quantification of unfractured blocks with the aim of optimization is illustrated by detailed studies on several quarries the algorithm used in this study can be applied as a powerful tool in the planning of a quarry and the future exploitation of dimension stone application of the described approach is demonstrated on practical examples of quarrying natural stones namely sandstone granite rhyolite etc block quarrying can be optimized by using the new 3d blockexpert approach the quantification of unfractured rock masses is also shown to contribute to a more ecological protection and the sustainable use of natural resources

controls on rock weathering rates by reaction induced hierarchical fracturing abstract weathering of rocks takes place through complex processes involving an intimate coupling between mechanical disintegration of the rocks and interactions between the exposed rock surface the hydrosphere and the biosphere it is still poorly understood how this coupling affects weathering rates and patterns produced by weathering here we show that the observed spheroidal weathering patterns in basaltic intrusions dolerites in the karoo basin in south africa are created through volume expanding reactions which set up stresses that not only lead to spalling of spheroidal layers of rock but also drive a large scale hierarchical fracturing process by which the dolerite is continuously undergoing domain division the fracture processes generates new reactive surface area in a self accelerating manner thus providing a first order control on the total weathering rate

u pb zircon and monazite geochronology of post collisional hercynian granitoids from the central iberian zone northern portugal abstract in the central iberian zone ciz of the iberian massif large volumes of granitoids were emplaced during the post collisional stage of the hercynian orogeny syn to post d3 the last ductile deformation phase twelve granitic units and a quartz monzodiorite were selected for a u pb zircon and monazite geochronological study they represent successive stages of the d3 event the ucanha vilar lamego sameiro and refoios do lima plutons are coeval 313 2 ma 319 4 ma 316 2 ma and 314 2 ma respectively and belong to the earliest stage later on the braga massif was emplaced its different units yielding the same age 309 3 ma for the braga granite 309 1 ma for the gonca granite and 311 5 ma for a related quartz monzodiorite the braga massif is subcontemporaneous with the agrela and celeiros plutons 307 3 5 ma and 306 2 ma respectively in agreement with field data the briteiros granite is younger 300 1 ma followed by the emplacement of the peneda geres massif geres paufito illa and carris granites the geres granite emplaced at 296 2 ma seems to represent a first magmatic pulse immediately followed by the intrusion of the paufito granite at 290 2 5 ma for the carris granite a minimum emplacement age of 280 5 ma was obtained based on these results the following chronology is proposed 1 syn d3 biotite granitoids 313 319 ma 2 late d3 biotite dominant granitoids 306 311 ma 3 late to post d3 granitoids ca 300 ma 4 post d3 granitoids 290 296 ma these chronological data indicate that successive granitic intrusions were emplaced in the ciz during a short time span of about 30 ma that corresponds to the latest stages of the hercynian orogeny a rapid and drastic change occurred at about 300 ma between a compressive ductile tectonic regime d3 ca 300 320 ma associated to calc alkaline monzonitic and aluminopotassic plutonism and a fragile phase of deformation d4 which controlled the emplacement of the subalkaline ferro potassic plutonism at 290 296 ma

sedimentology of magmatically and structurally controlled outburst valleys along rifted volcanic margins examples from the nuussuaq basin west greenland after a period of early palaeocene faulting and uplift of the nuussuaq basin west greenland two valley systems were incised into the underlying sediments incision of the older tupaasat valley took place during a single drainage event of large water masses which resulted in catastrophic deposition the valley was cut along early palaeocene nw to se trending normal faults clearly showing that the trend and the relief of the valley were structurally controlled the valley fill is up to 120 m thick and consists of a lower part of sandstones and conglomerates deposited from catastrophic flows characterized by very high concentrations of suspended coarse grained sediment load catastrophic deposition was followed by rapid decrease in flow discharge and the establishment of a lacustrine environment within the valley characterized by the deposition of heterolithic sediments the younger paatuutkloften valley system was mainly cut into the tupaasat valley fill which was completely or nearly completely eroded away in many places the younger valley is 1 2 km wide and up to 190 m deep incision of the paatuutkloften valley probably reflected renewed tectonic activity and uplift of the basin this phase was shortly followed by rapid major subsidence the valley fill deposits comprise a uniform succession of fluvial and estuarine sandstones the valley fill is topped by shoreface sandstones which are succeeded abruptly by offshore mudstones deposited shortly before and during the initial extrusion of a thick hyaloclastite succession the paatuutkloften valley fill is attributed to a very rapid rise in relative sea level contemporary with extensive volcanism it is suggested that this sequence of events coincided with the arrival of the north atlantic mantle plume in several respects the early palaeocene valley fill deposits of the nuussuaq basin are different from idealized facies models for incised valley systems and represent very special cases of incised valleys major differences from published examples include the dominance of catastrophic deposits and indications of large changes in relative sea level of several hundreds of metres taking place rapidly in less than 1 myr these changes were governed by the rise of the north atlantic mantle plume

on apatite fission track dating and the tertiary evolution of west greenland topography abstract combined with geological information apatite fission track aft data can impose valid thermal and temporal constraints however their uncritical interpretation may also lead to unsupported conclusions because fission tracks in apatite undergo measurable shortening even at surface temperatures model artefacts can potentially be mistaken for geological cooling events this problem can be especially acute when older fanning kinetic models are utilized instead of the newest curvilinear ones in any circumstances aft model results must be interpreted with considerable caution and should rarely be considered to supersede conventional geological wisdom the possibility that young cooling events are simply artefacts ought always to be entertained as an example this study considers aft data and model results that have been cited to suggest that today9s high mountains of west greenland are erosional remnants of a landmass uplifted during the neogene however in the best of circumstances the aft data in question are heavily contaminated and in the worst case they carry virtually no geological meaning although geological constraints require the faulted westward facing escarpment of west greenland9s disko region to have been erected after commencement of sea floor spreading in baffin bay the aft model based hypothesis that it was constructed in purely neogene time remains an unproven speculation

geology and tectonic evolution of palaeoproterozoic basins of the eastern capricorn orogen western australia abstract the palaeoproterozoic yerrida bryah padbury and earaheedy basins extend for about 700 km along the northern margin of the yilgarn craton and are part of the capricorn orogen the basins developed between ca 2 2 and 1 8 ga recording periods of sedimentation volcanism rifting accretion and passive margin tectonism the oldest is the 2 17 ga yerrida basin which began as an intracontinental sag within which siliciclastics and evaporites accumulated at about 2 0 ga convergence of the yilgarn craton and the glenburgh terrane closed an oceanic arm resulting in the accretion of oceanic crust and plateaux onto the yilgarn margin and the western side of the yerrida sag basin this accretion produced the narracoota formation which together with the clastic and chemical banded iron formation sedimentation that followed forms the bryah basin continuing collision resulted in the establishment around 1 96 ga of the padbury foreland basin developed on top of the bryah basin rocks the ca 1 83 ga convergence and collision of the pilbara and yilgarn cratons capricorn orogeny resulted in deformation of the bryah padbury basins and orogenic uplift with coarse clastic sedimentation accompanied by the eruption of flood basalts into the yerrida basin to the east of the collision zone and possibly postdating collision a passive margin was present sedimentation along it consisted of clastic and chemical sediments granular iron formation which form the earaheedy basin during the ca 1 79 ga yapungku orogeny due to the convergence of the north australian and western australian cratons the northern margin of the earaheedy basin was deformed stanley fold belt this last deformation event concludes the palaeoproterozoic history of the eastern capricorn orogen basins

the ilugissoq graphite andesite volcano nuussuaq central west greenland abstract the ilugissoq graphite andesite volcano on nuussuaq belongs to the asuk member of the paleocene vaigat formation it is the largest eruption site within the vaigat formation and is recognized as the source of the majority of the graphite andesite tuffs found in marine sediments in central nuussuaq the volcano consists exclusively of pyroclastic rocks containing a diverse lithic assemblage including sediment xenoliths the primary pyroclastic fragments consist of magnesian andesite with several weight percent of graphite which formed when mafic magma established a shallow level magma reservoir beneath the eruption site and within older clastic sediments from the nuussuaq basin magma modified mudstone is completely dominant in the xenolith assemblage and attests that the graphite andesite originated through prolonged high temperature assimilation of mudstone the eruptions took place on a marine shelf consisting of picritic hyaloclastites and subaqueous crater mounds the volcano consists of four overlapping crater cones aligned along a more than 4 km long nnw sse oriented fissure system two cones barely reached sea level whereas the other two reached up to 200 m above the sea the morphology of the pyroclastic rocks demonstrates that the volcano evolved through phreatomagmatic activity which diminished with time the magma never degassed sufficiently to reach a subaerial lava stage a moderate primary gas pressure well in excess of 100 bars in the graphite andesite magma facilitated the phreatomagmatic explosions which created the ilugissoq volcano the rocks of the volcano are rich in graphite and contain little or no native iron in comparison the contemporaneous and chemically similar subaerial lavas and breccias from disko and nuussuaq contain less graphite and more iron the differences are considered to be due to the extremely pressure dependent redox sensitivity of carbon oxygen equilibria in the range 1 bar the lavas to 500 bars the ilugissoq volcano eruptions in the ilugissoq volcano must have been accompanied by intense co and co2 emanations which would have represented a lethal hazard for all animal life in the volcano s surroundings

differential erosion of a mesozoic rift flank establishing the source of topography across karrat central west greenland the landscape of the karrat region central west greenland contrasts between high elevation low relief topography steep sided fjords and deep bathymetric troughs the mechanisms controlling its formation are highly debated with initial work suggesting it to be the result of episodic tectonic uplift throughout the late cenozoic and alternative models implying it is the product of more recent isostatic uplift in response to differential glacial erosion here the results of a comprehensive low temperature thermochronological study apatite fission track and apatite uth he and landscape evolution model are presented that helps establish the source of the modern elevated landscape and the region s complex geomorphology joint modelling of the apatite fission track and apatite uth he data outlines two significant periods of cooling in the mesozoic and cenozoic respectively the first 150 ma 110 ma correlates to the onset of extension between west greenland and eastern canada suggesting uplift of the region during active rifting while the second period 50 ma 0 ma is coeval to the cessation of volcanism in the region and likely represents widespread erosion these results suggest the basement escarpment likely remained at height during extrusive volcanism and was later uncovered following exhumation of the volcanic succession moreover this latter phase of exhumation is outlined in the results of landscape evolution modelling implying it likely encompassed localised differential erosion of the volcanic pile producing a pre glacial landscape that later aided ice stream onset and the advance of the uummannaq ice stream glacial exhumation of the region was likely characterised by differential erosion shaping the modern geomorphology through preferential ice stream development and isostatic rebound these results highlight the complex interaction between rift tectonics and surface processes across the karrat region and adds to a wider understanding of the post rift evolution of passive continental margins

regional uplift gas hydrate dissociation and the origins of the paleocene eocene thermal maximum much of the north atlantic region experienced hundreds of metres of transient uplift during the latest paleocene regional uplift should cause dissociation of gas hydrates stored in marine sedimentary strata and the subsequent release of carbon to the atmosphere should enhance warming through the greenhouse effect we have developed models of the spatial distribution of uplift to match observational constraints from sedimentary basins fringing the north atlantic in order to provide quantitative estimates of the carbon released upon uplift these models are coupled to a simple parameterisation of carbon storage in sub seafloor gas hydrates results of modelling indicate that large quantities of carbon can be released by uplift with some models generating over 2000 gt of carbon release the possibility that latest paleocene regional uplift occurred over the same time interval as onset of the paleocene eocene thermal maximum petm around 30 kyr cannot be ruled out using current stratigraphical observations or mantle convection models in this case the uplift mechanism alone can account for the magnitude and timing of the carbon isotope excursion associated with the petm alternatively if the duration of latest paleocene uplift was closer to the upper bound of around 1 myr or if other paleocene uplift events were equally significant then gas hydrate dissociation upon uplift could have contributed to longer term changes in ocean temperature and carbon isotope composition through the late paleocene these temperature changes in combination with development of the north atlantic land bridge during the latest paleocene culmination of uplift may be able to force rapid changes in ocean circulation and cause phenomena such as the petm

artificial weathering of spanish granites subjected to salt crystallization tests surface roughness quantification for hundreds of years two types of granite zarzalejo and alpedrete from the madrid region spain have been extensively used as building stones fresh specimens of both stone types have been sampled from their respective quarries and subjected to sodium sulphate salt crystallization test sct the resulting physical and chemical weathering patterns have been characterized by polarized light optical and environmental scanning electron microscopy water absorption under vacuum conditions and mercury intrusion porosimetry techniques were used to determine the pre and post sct porosity and pore size distribution the following non destructive techniques were performed to assess stone durability and decay ultrasound velocity us and surface roughness determination sr of intra and inter granular quartz feldspar and biotite minerals at the centre as well as at the corners and edges of specimen surfaces before the sct us values were lower and sr values higher in zarzalejo zar than alpedrete alp granite after sct the us values declined while sr rose in both types of granites with greater average differences in zar than alp for both parameters feldspar and biotite and their inter granular contacts were found to be the weakest and therefore the most decay prone areas of the stone the initial sr parameters were generally higher and rose more steeply after sct at the corners and around the edges of the specimens while behaviour was found to be similar in the two types of granite variations were greater in zar the less durable and more decay prone of the two surface roughness measurement of mineral grains in granite stones is a very useful in situ non destructive technique for quantifying salt crystallization mediated physical and chemical weathering the resulting quantification of decay and of related durability provides insight into the future behaviour of this type of stone commonly used in historic buildings

sedimentary response to mantle plumes implications from paleocene onshore successions west and east greenland the uplift history of the upper cretaceous paleocene sedimentary successions underneath the extensive tertiary flood basalts of west and east greenland supports recently described models for the generation of flood basalt provinces in response to rising hot mantle plumes however the sedimentary development indicates that the period of plume related uplift prior to eruption of volcanic rocks was very short 5 m y substantial regional uplift and faulting took place in west and east greenland in the early paleocene to earliest late paleocene resulting in a basinwide unconformity in west greenland the uplift was associated with fluvial peneplanation valley incision and catastrophic deposition in east greenland it was associated with fluvial peneplanation the cumulative uplift in west greenland is probably on the order of several hundred meters whereas in east greenland the observed uplift cannot be quantified in both west and east greenland this phase was shortly followed by rapid major subsidence associated with extensive volcanism it is suggested that this sequence of events reflects the arrival of the north atlantic mantle plume or plumes

differences in the quality of polishing between sound and weathered granites aesthetic characteristics are important when rocks are used as construction materials among all the surface finishes available the polished finish is the one which best enhances the rock attractiveness colour c roughness r and gloss g are surface properties usually used to assess the rock polishing in this research the crg properties were assessed in polished samples of three ornamental granites with different textures and physical mechanical properties one weathered and two sound c was evaluated in cie l a b and cie l c abhab systems r with ra and rz parameters and g using the 20 60 and 85 geometries the weathered granite presents a noticeable colour variation especially in the b parameter while the sound ones have a more homogeneous colour sound and more textural homogeneous granites have a low surface roughness and high gloss which are uniformly distributed the weathered granite shows a higher surface roughness and lower gloss with scattered distribution the mineral contacts are the main cause of the surface irregularities the results show the interdependence between the crg properties and stress the importance of the polishing process for enhancing the aesthetic characteristics of the granites crg properties could be used for quality control in granite processing plants thus avoiding noticeable differences in the facades of buildings particularly when weathered granites are used

evaluation of dimension stone in gneissic rocks a case history from southern finland abstract a dimension stone prospect in southern central finland was assessed by a detailed mapping geo radar survey and core drilling the prospect is a veined and bedded garnet cordierite gneiss consisting of a dark schistose medium grained palaeosome and a light coarse grained granitic leucosome both components are found mainly as thin units but the leucosome can occur as individual veins several metres thick which leads to disturbing variations in the appearance of the stone the soundness of the stone is defined by the amount of tight but open cracks in the palaeosome and weakness zones in the weathered leucosome as a whole the soundness is diminished down to 10 m below the outcrop surface furthermore a subhorizontal body of younger granite is identified at approx 8 20 m depth consequently the prospect is not feasible for production of dimension stone the core drilling was decisive in the final evaluation of the prospect because the true density of the cracks and the subsurface granite were identified by the method only with the use of core drilling could the proper interpretation of the characteristics of the prospect be made demonstrating the importance of three dimensional investigation of a dimension stone prospect

fracture characteristics in weathered granites abstract the variability of weathered materials is an important factor in the geotechnical characterization of rock for engineering purposes most engineering rock mass classifications include weathering schemes that separate the weathering profile into zones or grades that depend upon the engineering and geological properties of the rock many geotechnical characteristics including weathering are controlled by the density and arrangement of fractures within the rock but the relationships between fracture patterns and weathering grades are typically not addressed fracture characteristics were investigated in 13 exposures in five study areas in weathered granite in eastern asia all weathering grades were present but never in the same exposure two approaches were used to evaluate the field data 1 joint spacings were tabulated and examined within each weathering grade tabulated classification and 2 each exposure was classified according to the dominant weathering grade visual classification mean and median joint spacings and joint spacing frequency distributions were analyzed and compared statistically for each approach the box fractal dimensions for joint spacing were calculated for exposures classified visually in each weathering grade three dimensional models of fresh and weathered granite were also generated and sampled for comparison to the field data mean joint spacing is usually 25 or more closer in weathered granite than it is in fresh granite and the difference between the mean spacings for weathered granite and fresh granite tend to be statistically significant there are no significant differences between any distribution medians the joint spacing distributions for weathered granite and fresh granite are also not statistically significantly different and there are no significant differences among the joint spacing frequency distributions for the different grades of weathered granite fractal analysis of joint spacings however suggests spacing characteristics of fresh and slightly weathered sw granite are very different from those in moderately highly and completely weathered granite and sampling of three dimensional models for weathered and fresh granite supports this in an engineering context this suggests that joint spacing relationships in the various grades of weathered granite can be treated as the same regardless of weathering grade and that joint patterns in fresh granite must be evaluated separately this knowledge could result in significant time and cost savings in the geotechnical characterization of these materials

discontinuity modelling and rock block geometry identification to optimize production in dimension stone quarries abstract evaluating the reserves of commercial blocks in dimension stone quarries requires determining in situ block geometry furthermore to extract blocks the planes need to be cut and the intersection between the fracture network and the cutting patterns forms smaller blocks the optimization of the cutting patterns can increase quarrying efficiency resulting in less environmental damage in this paper a numerical algorithm was selected from various algorithms and was developed for in situ block identification the optimization approach was adopted to increase quarry productivity and to investigate quarrying direction on a large scale however on a small scale this approach was employed for checking the distance between the cutting planes according to the algorithms developed 3d quarryoptimizer was programmed in the matlab environment to determine the geometry of the blocks and to optimize extraction based on the quality classification of the blocks formed the algorithms developed have such advantages as the optimization approach and taking the geometry of the blocks into consideration this methodology was applied in a marble quarry and a granite quarry research conducted in the granite quarry showed that the program is a practical tool to determine the geometry of in situ blocks and their quality classification the marble quarry was studied for the optimization phase the large scale optimization indicated a maximum difference of 17 in the yield among several quarrying directions on a small scale however a 120 increase in quarry yield was achieved with the optimal interval between the cutting planes

relationships between joint separation and faulting an initial numerical appraisal abstract the relationship between secondary jointing and faulting and major faults was investigated using a regression analysis of average separation of joints and secondary faults versus distance from the closest major fault the analysis was carried out on 95 granite outcrop localities in calabria southern italy the main result of the regression analysis is expressed by s 0 013 d 0 457 where s is the average apparent separation and d is the distance from the closest master fault all values are expressed in meters the correlation coefficient was r 0 95 and the probability of the null hypothesis was 0 00 both data sets range over one order of magnitude thus the result of the analysis is reliable

quantifying transient mantle convective uplift an example from the faroe shetland basin the icelandic mantle plume generated maximum uplift in early paleogene times the faroe shetland basin which fringes the north atlantic margin of europe was close to the center of early paleogene icelandic plume activity three dimensional seismic reflection data from the faroe shetland basin reveal sedimentary geometries that allow a phase of transient uplift to be accurately reconstructed and quantified close to the paleocene eocene boundary circa 56 ma rapid uplift resulted in fluvial incision into marine sediments this unconformity was buried by nonmarine sediments recording the decay of transient uplift relief on the unconformity was 550 m constraining the minimum amount of surface uplift some 60 m of this uplift can be attributed to the isostatic response to erosional unloading tectonic uplift of over 490 m peaked and decayed within 3 ma rates of water loaded tectonic subsidence following peak uplift are several times greater than maximum expected postrift subsidence rates the amplitude and duration of this transient effect is best explained by a mantle convective phenomenon we suggest that a region of hot plume material flowed laterally beneath the lithosphere producing transient uplift which decayed when plume material was advected farther away our analysis suggests that under certain circumstances stratigraphic records can yield valuable quantitative information about aspects of mantle convective circulation

plume lithosphere interactions in rifted margin tectonic settings inferences from thermo mechanical modelling we present results from 2d and 3d thermo mechanical studies of plume lithosphere interactions in a rifted margin setting and compare inferences of these models with the northern atlantic volcanic rifted margin province we first present a series of 2d models with three different initial locations of the plume under the oceanic part of the rifted margin system under the area affected by lithospheric thinning by passive rifting and under continental lithosphere which has not been affected by extension prior to plume emplacement the style of final plume distribution appears to be controlled by its initial position with respect to different lithospheric segments and rheology of the mantle in the continent ocean transitional zone rather than by other parameters such as external forcing and rheological structure of the mantle plume the initial size of the mantle plume controls to a large extent the degree of plume head asymmetry for a strong rheology of the overlaying transitional lithosphere the effect of plume emplacement is mainly restricted to deep lithospheric levels in contrast a weak transitional mantle leads to plume induced continental break up when the plume head contributes to the formation of new oceanic lithosphere with asymmetrical propagation of hot plume material towards the continental segment a common feature of most 2d models is that initially a hot plume weakens the overlying lithosphere whereas at a later stage frozen mantle plume material is embedded into the lower part of the lithosphere forming dense and high velocity bodies we extend our 2d numerical modelling study to three dimensions and investigate the first order controls of continental break up and plume emplacement we demonstrate that the observed complex iceland plume geometry with up to 400 km southern propagation can be reproduced numerically in 3d and explained by pre imposed zones of lithospheric thinning along transform faults

the volcanic margins of the northern labrador sea insights to the rifting process 1 a new interpretation of seismic reflection data on the continental margin of northern labrador shows basement structures similar to those observed on other volcanic rifted margins seaward dipping reflections inner flows volcanic plateaus and lava deltas are observed on these data magnetic chron 27n 61 ma is coincident with the volcanic plateaus connecting these features to the paleocene volcanism farther north in davis strait therefore we are able to extend the region of volcanism about 500 km south along the margin similar structures are also observed on the conjugate west greenland margin below the volcanic plateaus gravity and wide angle seismic data show thick igneous crust which is fairly symmetrically distributed across the conjugate margins however the geometry of the thinned continental crust is not symmetrical a narrower zone of thinning is observed off northern labrador the thick igneous crust lies seaward of thinned continental crust which exhibits little or no underplating by the magmatic event this observation is compatible with recent models for the formation of nonvolcanic margins followed by a magmatic event late in the rift evolution in mesozoic time rifting of the cold thick cratonic lithosphere occurred between greenland and north america with minimal volcanic activity then in late cretaceous time the zone of rifting narrowed and localized seaward of the shelf creating a relatively narrow zone of lower lithospheric thinning and mantle upwelling into which the paleocene magmas were eventually channeled this scenario is supported by studies of mesozoic igneous rocks on land in coastal west greenland and labrador

formation uplift and dissection of planation surfaces at passive continental margins a new approach the usefulness of large scale low relief high level landscapes as markers of uplift events has become a subject of disagreement among geomorphologists we argue that the formation of low relief surfaces over areas of large extent and cutting across bedrock of different age and resistance must have been guided by distinct base levels in the absence of other options the most likely base level is sea level we have analysed west greenland landscapes in a recent study by combining the cooling history from apatite fission track analysis afta data with the denudation history from landscape analysis and the stratigraphic record an important difference between our approach and that of classical geomorphology is that we now have the ability to document when thick sections of rocks have been deposited and then removed the present day high level plateau in west greenland is the remnant of a planation surface that was formed by denudation that lasted c 20 million years during which up to 1 km of cover was removed after maximum burial at the eocene oligocene transition here we present additional afta data to show that the planation surface is the end product of cenozoic denudation even in basement areas and argue that phanerozoic sediments most likely of cretaceous palaeogene age must have been present prior to denudation the planation surface was offset by reactivated faults and uplifted to present day altitudes of up to 2 km the uplift occurred in two late neogene phases that caused incision of valleys below the planation surface and their subsequent uplift we therefore find that the elevated and deeply dissected plateau is evidence of episodic post rift uplift that took place millions of years after cessation of sea floor spreading west of greenland we suggest that other margins with similar morphology may also be characterized by episodic post rift uplift unrelated to the processes of rifting and continental separation rather than being permanently uplifted since the time of rifting as is commonly assumed copyright 2009 john wiley sons ltd

latest caledonian to present tectonomorphological development of southern norway abstract the regional resultant stress field of the northeastern north atlantic has shifted significantly throughout the phanerozoic in fennoscandian parts of the caledonian orogen mountain building which was characterized by nw se contraction reference to present north was followed by a collapse with transport both parallel and transverse to the mountain chain the late palaeozoic mesozoic saw several stages of e w to nw se extension varying in time and position local episodes of inversion are traceable in some cases particularly in connection with deep seated and long lived zones of weakness the cenozoic has to a larger degree been affected by compression including folding and basin inversion again some of the more pronounced effects of local inversion are related to pre existing fault systems neogene uplift of the western mountainous area in scandinavia can be unravelled by potential field study aft data and reflection seismic sections assuming that the region is close to isostatic equilibrium the uplifted areas must be supported at depth by substantial volumes of low density material within the crust or the mantle close to the crust mantle interface or close to the lithosphere asthenosphere interfaces a series of nw se oriented cross sections representing successive stages of development from the late caledonian to present were prepared and used to analyse the tectonomorphological development as related to the shifting stress configurations three stages are inferred stage 1 devonian late permian denudation of the caledonian mountain chain during the latest stage of closing of the iapetus ocean in early to mid devonian times the caledonian mountain chain reached its maximum elevation of perhaps as much as 8 9 km including the foreland basins to the east the average topographic gradient of the eastern flank may have been in the order of 1 3 the denudation of the caledonian mountains continued into the permian and by the end of the permian the mountain system was more or less obliterated with a gradient of the eastern flank probably continued to fall to less than 0 1 stage 2 triassic late cretaceous tectono thermal uplift of central south norway uplift of central south norway was rejuvenated in triassic times and continued throughout the jurassic and early cretaceous the gradient of the eastern flank increased to a maximum of approximately 0 15 and master structural elements like the laerdal gjende olestol fault complex again played important roles in the development stage 3 tertiary present renewed tectono thermal activity and post glacial rebound a second phase of post caledonian tectono thermal uplift of south central norway started in oligocene time again increasing the gradient of the eastern flank of south norway around 0 2

cenozoic uplift of europe 1 following the diachronous cretaceous neogene onset of seafloor spreading in the northern atlantic and arctic oceans the european passive margin and continental europe underwent a generalized uplift this long wavelength cenozoic uplift has been attributed either to mantle plumes and or to the far field compression in the alps we suggest an alternative mechanism or concause where the asthenosphere depleted at the mid atlantic ridge was shifted relatively eastward beneath the continent because of the net rotation of the lithosphere the partial melting at the oceanic ridge leaves the asthenosphere lighter when migrating beneath the european continental lithosphere the substitution of the older denser mantle with the depleted lighter asthenosphere should have generated an isostatic rebound and associated uplift of about 300 600 m dynamic topography exerted by the mantle flowing eastward could have enhanced the uplift process

evaluation of the quality of a granite quarry abstract the determination of the quality of a mass of granite with a view to its exploitation for ornamental purposes is carried out by means of the identification of the geological geotechnical and aesthetic factors that characterize the granite in order to draw up an optimal exploitation method for any given granite deposit an assessment of the relationship existing between these factors and the quality of the block is of the utmost importance using as a starting point data based on the observation of these factors at an extraction bank a simple linear index was elaborated using multivariant techniques permitting the classification of each block in terms of quality subsequently using geostatistical techniques the index is applied to areas of the extraction bank for which there are no a priori data with a view to predicting possible areas of maximum quality included is a description of an application whereby the quality of a granite quarry was evaluated on the basis of 569 observations at an extraction bank the methodology developed may be considered an objective quality evaluation method applicable to ornamental rock quarries

characterisation of monzogranitic batholiths as a supply source for heritage construction in the northwest of madrid abstract the church of the assumption of our lady in valdemorillo madrid spain is almost entirely built with granitoids the studies and analyses were focused on the oldest part of the building ghosts corner which will be restored and rehabilitated in the near future homogeneous monzogranite is the predominant granitoid used in the ghosts corner followed by granitic porphyry porphyrytic monzogranite gneiss and leucogranite the original quarries that supplied homogeneous monzogranites for the first construction stages correspond to blocks present in the monument s surroundings quarries that supplied the granitic porphyries correspond to the dykes located to east southeast of valdemorillo which are oriented n s in relation to their intrusion direction the combined use of ultrasonic velocity and schmidt hammer techniques allowed first selection of the most representative blocks and ashlars for sampling this reduced sampling to a minimum but yielded representative results for the whole building second the combined values were used to compare results for the building stones of the church to rocks from the surrounding quarries stones from the building showed lower ultrasonic and schmidt hammer values and higher porosity and water saturation values compared to the original quarry rocks the anisotropy indices are directly related to the decay processes in the stone spalling of homogeneous monzogranite and grain disintegration in granitic porphyries finally the methods applied are inexpensive easy to use and non destructive techniques very advisable properties when working with built heritage

ultrafast mantle plumes and implications for flood basalt volcanism in the northern atlantic region abstract recent geochemical and geochronological data on paleocene flood basalts from west greenland se greenland and the british isles show that volcanic activity at these widely separated locations commenced nearly simultaneously around 61 62 ma ago and that the duration of this initial phase of flood basalt magmatism was of the order of a few million years or less a small fast moving upper mantle plume which rapidly spreads out horizontally on encountering the base of the lithosphere appears to be a viable mechanism to explain these observations however in order to reconcile the idea of an ultrafast plume with the observed plate velocities a physical mechanism is needed for inducing a separation of timescales between the plume speed and the surrounding mantle circulation thermal convection with a non newtonian temperature and depth dependent rheology provides such a mechanism wherein extremely fast plumes ascending at velocities between one to tens of meters per year can be produced in an otherwise slowly convecting mantle moving at cm yr this transport mechanism is capable of bringing up very hot matter from the transition zone to the lithosphere the fast upward velocities lead to the production of high viscous heating rates surrounding the plume upon impinging the lithosphere it is thus possible to explain the near simultaneous onset of magmatism in west greenland se greenland and the british isles in the early tertiary by a fast moving mantle plume spreading out horizontally with a velocity of around 0 5 m yr for resolving numerically the thermal mechanical state of these strongly time dependent mantle flows extremely high spatial resolution on the kilometer scale is required finally we suggest the possibility that the source of the fast upper mantle plume under iceland may be rooted in the lower mantle this is consistent with the recent findings by seismic tomography of a deep mantle plume under iceland

mantle plume uplift in the sedimentary record origin of kilometre deep canyons within late neoproterozoic successions south australia in south australia canyons 200 250 km long are incised to depths of c 1 5 km in late neoproterozoic after c 590 ma marine deposits of the adelaide fold belt and canyons 90 km long and 700 m deep occur in correlative marine strata of the officer basin 1000 km to the nw in the adelaide fold belt the isotopic signature of limestone veneering canyon walls canyon sinuosity and sedimentary structures in canyon fill suggest that the canyons were cut subaerially and filled by shallow water marine deposits during coastal onlap eustacy cannot account for the kilometre scale change in sea level required for subaerial canyon erosion and chemostratigraphy and the lack of evaporites at that stratigraphic level in southern australia argue against a messinian style drawdown in each region uplift and crustal extension preceding or coeval with canyon incision are indicated by a regional unconformity turbidite or mass flow deposition and extensional faults these features and canyon incision may be explained by regional uplift above a rising mantle plume over a distance of 1000 km in southern australia flood basalt volcanism in the officer basin tentatively dated at 563 40 ma may have followed this uplift mantle plume uplift is expressed in the sedimentary record by emergent trends in facies regional thinning regional unconformities turbidites gravity slides normal faults and incised canyons and palaeovalleys

the transition from sedimentation to flood volcanism in the kangerlussuaq basin east greenland basaltic pyroclastic volcanism during initial palaeogene continental break up primary basaltic pyroclastic deposits compose volumetrically c 35 50 of the lower palaeogene vandfaldsdalen mikis and haengefjeldet formations within the lower volcanic series of the east greenland flood basalt province the eruption and emplacement mechanisms of these deposits can be used to evaluate the volcanotectonic evolution of continental break up and initiation of flood basalt volcanism we present a revised stratigraphy for the pre volcanic sedimentary rocks and synvolcanic pyroclastic and epiclastic deposits and lavas from the kangerlussuaq basin east greenland primary basaltic pyroclastic deposits range from airfall tuffs to bomb beds surge deposits and vent sites with cinder cones early volcanism was apparently restricted to localized basins and formed shield volcano structures 30 40 km in diameter that are characterized by a heterogeneous sequence of intercalated hyaloclastites sediments pyroclastic deposits and lavas the lateral variation of deposit morphology reflects distance from source and indicates a migrating locus of volcanism along the axis of rifting towards the ne paired with continued down dropping of inactive volcanic centres the complex stratigraphic architecture of the initial volcanic deposits reflects local tectonic and sedimentary processes interacting with regional flood basalt volcanism and continental rifting

three dimensional fracture distribution in relation to local cooling in a granitic body an example from the toki granitic pluton central japan this paper describes a spatial distribution of fracture frequency fracture number per unit interval in the toki granitic pluton central japan and their evaluation with respect to cooling behavior after solidification of the pluton three dimensional distribution of fracture frequency of all fractures all angle fractures based on borehole television data collected from 19 boreholes shows that 1 the central region of the granite has a high fracture frequency and 2 fracture frequency decreases with decreasing elevation measured from the mean sea level with the exception of the west side of the body the development of sub solidus reaction textures reflects the annealing duration of the pluton after solidification the extent of sub solidus reaction textures was measured at two neighboring positions and the difference was divided by the distance between the two positions the resulting quantity is here defined as a local cooling indicator lci we observed a related pattern between the distribution of fracture frequency and lci the high lci region corresponds to the region with a high frequency of all fractures and vice versa this relation indicates that fracture genesis has been mostly controlled by local cooling after solidification which caused thermal stress thus the three dimensional pattern of lci is a potential diagnostic tool for obtaining the spatial distribution of all fractures

abandoned stone quarries in and around the izmir city centre and their geo environmental impacts turkey there are 70 abandoned quarries in and around izmir city centre of these quarries 56 are in andesites 2 are in dasitic lavas 4 are in flysch and 8 are in limestones the quarries initially located near the izmir city centre are now within the city centre because of the expansion of the urbanization due to the rapid increase of population geo environmental problems identified in the abandoned quarry sites are slope stability problems such as sliding and toppling geotechnical study of the abandoned stone quarries in and around the city centre of izmir which has been carried out involves the recording and determining the properties of discontinuities for stability assessment of already failed and standing slopes in the quarries using stereographic projection techniques and the statistical evaluation of different types of rock mass movements in these quarries the number of mass movements that had already occurred and are likely to occur in 70 quarries lying in and near izmir have been determined as 84 totally stability analyses of rock slopes have shown that rock falls toppling plane and wedge failure type rock mass movements are more common in the south of izmir bay but toppling type slope failures are more frequent in the north

tectonostratigraphic evolution of the labrador margin atlantic canada abstract the labrador continental margin provides a rich source of data with which to study the relationships between stratigraphy tectonics and paleoenvironment we have completed a regional seismic interpretation and integrated this with new biostratigraphic data based on analyses of palynomorphs from wells in the hopedale and saglek basins which occur on this margin our results are summarized in a tectonostratigraphic chart which displays new and consistent age control for the major lithostratigraphic units and provides more precise evaluation of their depositional and paleoenvironmental history we have identified and dated six regional unconformities in the wells and we can recognize several others on the seismic data the older unconformities cretaceous are related to the tectonics of rifting and seafloor spreading and may delineate the onset of different stages of the rift process in the paleocene early eocene unconformity development was influenced by episodic volcanism due to the passage of the proto iceland hotspot to the north and to a major change in spreading direction in the labrador sea many of these unconformities are also identified in offshore southwest greenland and the grand banks suggesting widespread controlling mechanisms during the post seafloor spreading stage the effects of mass wasting and slumping and of paleoenvironmental controls on the stratigraphy were more pronounced we discuss the petroleum potential of the hopedale basin in terms of the structures we see on the seismic data and highlight the bjarni formation which likely contains the most prospective source and reservoir rocks in this basin

timing and mechanisms of north atlantic cenozoic uplift evidence for mantle upwelling postrift domal uplift patterns are a distinct feauture of northern north atlantic margins on the basis of apatite fission track data offshore seismic stratigraphy geomorphology gravity and seismic tomography we argue that southern norway is characterized by predominantly neogene domal uplift currently available data suggest similar processes for other uplifted regions such as spitsbergen northern norway the british isles aad parts of east greenland

development of the continental margins of the labrador sea a review abstract the labrador sea is a small oceanic basin that developed when the north american and greenland plates separated an initial period of stretching in early cretaceous time formed sedimentary basins now preserved under the continental shelves and around the margins of the oceanic crust the basins subsided thermally during late cretaceous time and a second episode of tectonism took place during latest cretaceous and early paleocene time before the onset of sea floor spreading in mid paleocene time around the northern labrador sea davis strait and in southern baffin bay voluminous picrites and basalts were erupted at and shortly after the commencement of sea floor spreading volcanism occurred again in early eocene time at the same time as sea floor spreading commenced in the northern north atlantic farther southeast along the labrador and southern west greenland margins oceanic crust is separated from continental crust by highly stretched but non magmatic transition zones which developed before sea floor spreading a complex transform zone which developed during sea floor spreading in late paleocene and early eocene time separates continental and oceanic crust along the baffin island margin the greenland and labrador ocean continent transitions are asymmetric across the only available conjugate cross sections however a cross section through the labrador margin farther north resembles the greenland cross section in the conjugate pair more than it does the labrador cross section of this pair consideration of the geological history of the area suggests that the non magmatic transition zones may have formed by slow extension of a few millimetres per year through a period of 53 ma during cretaceous and early paleocene time

determination of the regions used as facing and building stone according to the material characteristics in an andesite quarry the purpose of this study is to determine the variations within a certain area in the values of unit volume weight water absorption capacity by mass uniaxial compression strength and bohme surface abrasion resistance which are among the physical and mechanical properties of andesite existing in the andesitic marble quarry in the cubuk district in the city of ankara turkey in line with this purpose the working area was divided into grids at equal intervals and tests were done by taking andesite samples from each grid point the data obtained aims to determine the regions of andesite in the working area that are suitable and unsuitable for being facing and building stone according to the tse standards hence unnecessary production will be avoided by ensuring that production occurs in this andesite quarry only in the areas which are suitable for facing and building stone

the influence of the characteristics of quartz and mineral deterioration on the strength of granitic dimensional stones it is important to have a thorough knowledge of the petrographic characteristics of rocks to evaluate and understand their mechanical behavior this paper deals with the influence of the texture and the mineral characteristics of nine portuguese granites employed as dimensional stones this study evaluates different mineral characteristics such as mineral deterioration grain size quartz fissuration and the contacts between quartz and others mineral groups the main differences in the studied granites were identified clarifying the relationship between the petrographic characteristics the consequences on their respective mechanical behavior were subsequently evaluated the physical and textural characteristics of quartz in the studied granites have proven to be very important for understanding the behavior of granitic rocks under compressive stress uniaxial compressive strength values are not proportional to the quartz feldspar ratio or quartz content and there is a tendency for strength to decrease with the increase in quartz this could be related to the increase in quartz quartz contacts and the decrease in the rock capacity for accommodating the deformation