three dimensional in situ stress evaluation using a new under coring technique the tseng wen reservoir transbasin water tunnel the tseng wen reservoir transbasin water tunnel has broken the historical record of the maximum overburden of a tunnel within taiwan the three dimensional in situ stresses at the tunnel were evaluated using acoustic emission ae and deformation rate analysis dra with an under coring technique this is the first time that the ae and dra have been used in evaluating an in situ stress in taiwan as cores drilled in different directions are required for the three dimensional stress evaluation but the in situ borehole drilling is usually limited to the vertical direction small samples 2 28 cm in diameter and 4 56 cm in length were under cored from the borehole cores in six directions to evaluate the in situ stresses cyclic uniaxial compressive loadings were artificially applied to the changchikeng sandstones under cored from the outcrops the experimental results validate the definitiveness of using under cored samples at different pre stresses with ae and dra then cores taken from the tseng wen reservoir transbasin water tunnel site at a great depth of 416 739 m underground were under cored the experimental results indicate that the major principle in situ stress is from 30 8 to 39 mpa and is in the directions of se nw and sw ne at different depths

geochemistry and nd isotope systematics of archaean granites of the eastern goldfields yilgarn craton australia implications for crustal growth processes abstract the archaean granites and granitic gneisses of the eastern goldfields in the yilgarn craton western australia can be divided into two major groups high ca and low ca and three minor groups high hfse high field strength elements mafic and syenitic the high ca group 68 77 sio 2 with high al 2 o 3 na 2 o and sr and low y shares many features with typical archaean tonalite trondhjemite suites but has higher k 2 o rb and th contents the low ca group 70 76 sio 2 differs from the high ca group in having lower al 2 o 3 cao and na 2 o but higher k 2 o rb th zr y la and ce contents granites of the high hfse mafic and syenitic groups form a minor component 10 20 of the eastern goldfields granites the siliceous 74 77 sio 2 high hfse granites are restricted to a narrow nnw trending zone and are characterised by high tio 2 total feo mgo y zr and ce but only moderate rb th and pb contents the a type syenites 50 68 sio 2 are distinguished by their high total alkalies and mainly occur along tectonic lineaments the mafic group 55 70 sio 2 is lithologically diverse and exhibits a wide range of k 2 o rb th la and ce contents granite emplacement occurred between 2 69 and 2 60 ga contemporaneous with or post dating greenstone formation nd values for the high ca mafic and syenitic groups are similar mostly 0 0 to 2 5 whereas those for the low ca group show a pronounced polarity from 4 5 in the west to 2 0 in the east nd depleted mantle model ages for the low ca granites range from 3 2 ga in the west to 2 75 ga in the east model ages for the high ca group 2 75 2 9 ga overlap with ages for inherited zircons from these granites the high ca granites appear to have been derived at high pressures by partial melting of a mafic to intermediate source subducted oceanic crust crustal underplate or thickened crust or remelting of an older tonalitic source derived by such a process if the high ca granites were largely crust derived then their extensive source rocks must have formed less than 250 ma prior to granite formation the low ca granites appear to be the products of crustal reworking probably from a tonalitic to granodioritic protolith that was progressively younger towards the east perhaps in the order of several hundred million years younger or involved an additional younger component the localisation of the crustally derived high hfse granites suggests either geochemical zonation of the crust or specific tectonic processes such as rifting the mafic granites and possibly the syenites imply a significant mantle contribution and new crustal growth although the extent is equivocal the crust of the eastern goldfields appears to have been generated by both lateral and vertical accretion over a significant period from or before 3 0 ga until the time of granite emplacement

syenite associated disseminated gold deposits in the abitibi greenstone belt canada a distinct group of gold deposits in the abitibi greenstone belt is spatially associated with quartz monzonite to syenite stocks and dikes the deposits occur mainly along major fault zones in association with preserved slivers of alluvial fluvial timiskaming type sedimentary rocks the deposits consist of disseminated sulfide replacement zones with variably developed stockworks of quartz carbonate k feldspar veinlets within zones of carbonate albite k feldspar and sericite alteration the syenitic intrusions are broadly contemporaneous with deposition of timiskaming sedimentary rocks and together with disseminated gold mineralization they have been overprinted by subsequent regional folding and related penetrative cleavage disseminated gold orebodies occur within composite syenitic stocks or along their margins along satellite dikes and sills and along faults and lithologic contacts away from intrusions orebodies in these different positions are interpreted to represent proximal to distal components of large magmatic hydrothermal systems centered on and possibly genetically related to composite syenitic stocks

back analysis of an excavated slope failure in highly fractured rock mass the case study of kargar slope failure iran this paper examines the failure of kargar cut slope located at the south part of esfahan subway using analytical and numerical back analysis methods the excavated trench has 27 m depth with near vertical walls due to the space limitation around it the geology of the area comprises weathered and heavily jointed shale and sandstone overlaid by alluvium deposits despite the slope being supported by shotcrete and fully grouted rock bolts a catastrophic failure occurred at the east wall due to the uncertainty about the causes of failure initiation back analyses have been performed via both the limit equilibrium and numerical method for considering various probable mechanisms in the back analysis with limit equilibrium method the rock mass is assumed as an equivalent continuum and hoek brown failure criterion and geological strength index gsi are applied to calculate the shear strength parameters the results show that gsi value was 33 in the failed mass in the numerical back analysis the distinct element method is applied to study the contribution of rock joints to the failure and progressive rock mass strength degradation until failure the results show that threshold values of joint cohesion and friction were 0 2 mpa and 30 respectively also the modeled slip surface being step shaped agrees with the observed one

cassini imaging of titan s high latitude lakes clouds and south polar surface changes 1 cassini s imaging science subsystem iss has been observing titan since april 2004 compiling a nearly global surface map and monitoring the surface and atmosphere for activity early images of the south polar region revealed numerous dark surface features and contemporaneous convective cloud systems suggesting the presence of hydrocarbon lakes similar to those later detected at titan s north pole intriguingly repeated south polar imaging by iss revealed differences consistent with ponding of hydrocarbon liquids on the surface due to precipitation from a large storm more recent iss images of high northern latitudes illustrate the full extents 500 000 km2 of hydrocarbon seas sections of which have been observed by cassini s radar these observations demonstrate dynamic processes at work on titan and that the poles harbor liquid hydrocarbon reservoirs the extents of which differ from pole to pole and which may be coupled to seasonally varying circulation

kita uebaru natural rock slope failure and its back analysis a large landslide occurred in kita uebaru or asato area of nakagusuku village in okinawa island japan on 10 june 2006 after a rainy period of about 9 days the total rainfall was 126 mm from june 8 till the time of the landslide this period this landslide destroyed several buildings and roads and the total travel distance of the landslide was about 110 m in this article the authors were concerned with the initiation conditions of kita uebaru landslide and post failure motions of the landslide body the observations made in the landslide area structural geology analyses and outcomes of geotechnical investigations are described first then possible causes of the landslide are investigated through back analyses using as inputs the geological structure and the strength properties of planes of discontinuities involved in the sliding processes the final part of the article is concerned with the simulation of post failure motions of the landslide body the results of the investigations and back analyses indicate that the failure plane was bi planar and the heavy torrential rainy period for about 3 days was the main cause of initiation of the landslide the mechanical model presented in this article was capable of capturing the overall features of the landslide body following the initiation of the failure

cryovolcanic features on titan s surface as revealed by the cassini titan radar mapper abstract the cassini titan radar mapper obtained synthetic aperture radar images of titan s surface during four fly bys during the mission s first year these images show that titan s surface is very complex geologically showing evidence of major planetary geologic processes including cryovolcanism this paper discusses the variety of cryovolcanic features identified from sar images their possible origin and their geologic context the features which we identify as cryovolcanic in origin include a large 180 km diameter volcanic construct dome or shield several extensive flows and three calderas which appear to be the source of flows the composition of the cryomagma on titan is still unknown but constraints on rheological properties can be estimated using flow thickness rheological properties of one flow were estimated and appear inconsistent with ammonia water slurries and possibly more consistent with ammonia water methanol slurries the extent of cryovolcanism on titan is still not known as only a small fraction of the surface has been imaged at sufficient resolution energetic considerations suggest that cryovolcanism may have been a dominant process in the resurfacing of titan

great jurassic thrust sheets in beishan north mountains gobi areas of china and southern mongolia abstract jurassic thrust sheets with minimum displacements of 120 180 km have been discovered within the hercynian indosinian orogenic belt of the beishan of china and south gobi area the thrusts strike e w extend over 1200 km in length and carried meso proterozoic massive dolomitic limestones over strata ranging from neoproterozoic cryogenian and terminal proterozoic to lower middle jurassic slip linear plots based on kinematic indicators such as slickenlines and groove lineations fiber lineations and drag folds adjacent to the fault surface vergence of folds and imbricated thrusts in the upper plate indicate northward movement in the beishan area to the west and southward movement in the south gobi area to the east the two major thrust faults the beishan thrust and south gobi thrust are presumably separated by a major tear fault the ruo shui fault the major thrust faults were later deformed into a series of e w antiforms and synforms and the sheets are separated due to erosion into a number of klippen mainly located on synforms of the major faults the yagan metamorphic core complex which is a result of an extensional event that postdates the thrust event yields an 40 ar 39 ar plateau age of 155 1 10 ma and rb sr isochron age of 153 6 2 ma the thrust sheets formed during the late middle jurassic long after the closure of any oceans in the study area previously reported for this region and are ascribed to a phase of intracontinental deformation the closing of the jurassic tethys or retroarc deformation behind an active continental margin at the southern edge of asia prior to the tethyan collision or and the closing of mongolo okhotsk oceans might be responsible for this event

formation of systematic joints in metamorphic rocks due to release of residual elastic strain energy otago schist new zealand abstract we present the first regional study of joints in the jurassic cretaceous otago schist new zealand the purpose of this study was to explore the origin and mechanism of joint formation in metamorphic rocks especially any possible association between brittle and previous ductile deformation the otago schist is cut by numerous systematic joints up to tens of metres long at any one exposure we measured the orientation of joints schist foliation planes and quartz rods mineral lineations at 46 sites across the otago schist and calculated the spherical angles between their means in relatively high metamorphic grade schists greenschist facies typically one systematic joint set has developed sub perpendicular to penetrative foliation and lineation irrespective of foliation and lineation orientations this relationship also holds in lower grade schists pumpellyite actinolite facies but more than one joint set is occasionally present the flanking unfoliated schist protoliths prehnite pumpellyite facies contain no systematic joint sets a late cretaceous age for schist joint formation is indicated on the basis of lack of joint continuation into late cretaceous conglomerates that unconformably overlie jointed schists cooling history consistent orthogonality of joints with foliation and lineation and lack of relationship of systematic joints to late cenozoic plate boundary features we propose a model for joint formation during late cretaceous exhumation of the schist and suggest that the systematic joints formed due to release of residual elastic strain energy preserved in the schists from early cretaceous ductile deformation

a rough surface scattering function for titan radar studies 1 numerous studies show a relationship between radar backscattering and surface roughness while estimating the statistical properties of small scale topography is of particular interest for geologic analysis of cassini radar data there is no analytic description of radar scattering over a wide range of incidence angles and roughness this paper presents an empirical function that links the rms slope at the horizontal scale of the wavelength and hh or vv polarization radar echoes the model is based on comparison of 24 cm wavelength airsar data for lava flows in hawai i at incidence angles of 25 to 55 with topographic profiles at 25 cm posting comparison of model predictions to the range of observed titan echoes suggests that the radar return is often dominated by a component arising from subsurface scattering

titan radar mapper observations from cassini s t3 fly by cassini s titan radar mapper imaged the surface of saturn s moon titan on its february 2005 fly by denoted t3 collecting high resolution synthetic aperture radar and larger scale radiometry and scatterometry data these data provide the first definitive identification of impact craters on the surface of titan networks of fluvial channels and surficial dark streaks that may be longitudinal dunes here we describe this great diversity of landforms we conclude that much of the surface thus far imaged by radar of the haze shrouded titan is very young with persistent geologic activity

radar evidence for liquid surfaces on titan arecibo radar observations of titan at 13 centimeter wavelength indicate that most of the echo power is in a diffusely scattered component but that a small specular component is present for about 75 of the subearth locations observed these specular echoes have properties consistent with those expected for areas of liquid hydrocarbons knowledge of the areal extent and depth of any deposits of liquid hydrocarbons could strongly constrain the history of titan s atmosphere and surface

radar investigation of mars mercury and titan radar astronomy is the study of the surfaces and near surfaces of solar system objects using active transmission of modulated radio waves and the detection of the reflected energy the scientific goals of such experiments are surprisingly broad and include the study of surface slopes fault lines craters mountain ranges and other morphological structures electrical reflectivities contain information about surface densities and to some extent the chemical composition of the surface layers radar probes the subsurface layers to depths of the order of 10 wavelengths providing geological mapping and determinations of the object s spin state radar also allows one to study an object s atmosphere and ionic layers as well as those of the interplanetary medium precise measurements of the time delay to surface elements provide topographic maps and powerful information on planetary motions and tests of gravitational theories such as general relativity in this paper we limit our discussion to surface and near surface probing of mercury mars and titan and review the work of the past decade which includes fundamentally new techniques for earth based imaging the most primitive experiments involve just the measurement of the total echo power from the object the most sophisticated experiments would produce spatially resolved maps of the reflected power in all four stokes parameters historically the first experiments produced echoes from the moon during the period shortly after world war ii see e g evans 1962 but the subject did not really develop until the early 1960s when the radio equipment was sufficiently sensitive to detect echoes from venus and obtain the first doppler strip maps of that planet the first successful planetary radar systems were the continuous wave cw radar at the goldstone facility of the caltech s jet propulsion laboratory and the pulse radar at the mit lincoln laboratory all of the terrestrial planets were successfully studied during the following decade yielding the spin states of venus and mercury a precise value of the astronomical unit and a host of totally new discoveries concerning the surfaces of the terrestrial planets and the moon this work opened up at least a similar number of new questions although the early work was done at resolution scales on the order of the planetary radii very rapid increases in system sensitivities improved the resolution to the order of 100 km but always with map ambiguities recently unambiguous resolution of 100 m over nearly the entire surface of venus has been achieved from the magellan spacecraft using a side looking synthetic aperture radar reviews of the work up to the magellan era can be found in evans 1962 muhleman et al 1965 evans hagfors 1968 see chapters written by g pettengill t hagfors and j evans and ostro 1993 the radar study of venus from the magellan spacecraft was a tour de force and is well described in special issues of science volume 252 april 12 1991 and in the journal of geophysical research volume 97 august 25 and october 25 1992 venus will not be considered in this paper even though important polarization work on that planet continues at arecibo goldstone and the very large array vla in this paper we review the most recent work in earth based radar astronomy using new techniques of earth rotation super synthesis at the vla in new mexico operated by the national radio astronomy observatory and the recently developed long code techniques at the arecibo observatory in puerto rico operated by cornell university note it was recently brought to our attention that the vla software doubles the flux density of their primary calibrators consequently it is necessary to half the radar power and reflectivity numerical values in all of our published radar results from the vla goldstone radar the symbiotic relationship in these new developments for recent advances in our understanding of mercury and mars is remarkable vla imaging provides for the first time unambiguous images of an entire hemisphere of a planet and the long code technique makes it possible to map mars and mercury using the traditional range gated doppler strip mapping procedure which was apparently developed theoretically at the lincoln laboratory by paul green based on a citation in evans 1962 richard goldstein was the first to obtain range gated planetary maps of venus as reported in carpenter goldstein 1963 such a system was developed earlier for the moon as reported by pettengill 1960 and pettengill henry 1962 we first discuss the synthesis mapping technique

titan s surface from reconciled cassini microwave reflectivity and emissivity observations abstract the surface of titan saturn s largest moon appears to consist of solid hydrocarbons or co2 with considerable small scale structure according to a new electromagnetic scattering model that uses both cassini radar reflectivity and emissivity measurements our model resolves a well known ambiguity in active and passive observations of surfaces namely that the dielectric constant retrieved from radiometric data is usually less than that obtained from radar backscatter analysis we present here parameters of titan derived from radar and radiometric responses using a single set of surface physical descriptors the observed dielectric constant ranges from 1 75 2 5 consistent with the solids above but also with unconsolidated water or water ammonia ice inferred rms slopes of the surface range from 10 16 at cassini s 2 2 cm with radar albedos of about 30 emissivities of the surface are quite high on the order of 90 we find that the majority of the backscattered radar energy results from volume rather than surface scattering processes thus large scale variations in radar brightness are mainly diagnostic of composition and structure within titan s near subsurface the high level of volume scatter about 15 of incident energy and consequent high radar albedo suggest significant wavelength scale structure and multiple scatter within the medium this is most consistent with a surface composed either of ubiquitous mm size bubbles within the ice analogous to a vesicular cryolava or structures similar to ice pipes and lenses found in terrestrial ice sheets the cryovolcanic hypothesis suggests planet wide resurfacing by active volcanism to explain the large scale uniformity of observed backscatter if the lens pipe mechanism pertains it can imply percolation of precipitating liquid or surface melt through the titan firn

hydrothermal alteration and mineralization of the galore creek alkalic cu au porphyry deposit northwestern british columbia canada the late triassic galore creek porphyry district is the largest accumulation of cu au prospects in british columbia canada in terms of contained metal the principal economic resource is the central zone deposit it comprises three high grade centers the au rich north and south gold lenses and the cu dominated central replacement zone alteration footprints ore shells and porphyry intrusions in these centers dip 45 to 60 to the west in the north gold lens and southwest in the south gold lens and central replacement zone indicative of significant postmineral tilting this inclination created an oblique vertical expression of the central zone at surface and at depth providing a 700 m depth profile through the deposit galore creek is considered to be the end member of the silica undersaturated class of alkalic porphyry cu au deposits it displays a unique hydrothermal alteration footprint generally devoid of quartz veining despite the lack of crosscutting veins a paragenetic sequence of several discrete potassic and calcic alteration events has been established during main stage alteration two mineralization events occurred that formed the economic resource in the central zone highly oxidizing fluids derived from porphyritic syenite to monzonite intrusions produced initial potassic alteration and sulfide mineralization in the north gold lens and south gold lens cu au ore shells are characterized by a gold rich core dominated by bornite associated with hematite dusted orthoclase specular hematite and anhydrite the second period of hydrothermal activity caused brecciation and calcic alteration in the central replacement zone the calcic fluids formed hydrothermal cement grading from ti rich andraditic to grossularitic garnet in the core of the breccia to a diopside and magnetite dominated assemblage at the margins calcic alteration also formed in the surrounding host rock this alteration event was followed by potassic alteration and mineralization characterized by biotite anhydrite and chalcopyrite in the cu rich ore shell of the central replacement zone most of the au is hosted in bornite that is spatially associated with oxidized reddened rock units dominated by an alteration assemblage of orthoclase hematite specular hematite garnet anhydrite high grade cu in the central zone is related to abundant chalcopyrite that has commonly replaced an assemblage of biotite magnetite diopside this distinct spatial separation strongly suggests that the local redox environment within the wall rocks governed sulfide and gold distributions the switch from early au rich mineralization to late stage cu dominated mineralization appears to have been controlled by varying redox conditions within the magma the change from more oxidized alteration assemblages fe3 fe2 to more reduced assemblages fe3 fe2 is indicative of a change in oxidation potential that may have propelled sulfide saturation in the magma and thus the subsequent depletion of most of the au

investigation of key techniques on floor roadway support under the impacts of superimposed mining theoretical analysis and field study various sizes of coal pillars will be formed after the mining of close distance coal seams the concentrated stress formed on the coal pillars can cause serious deformation and failure to the roadway below floor roadway wantian coal mine in guizhou was taken as an example to study the stress propagation and distribution of roadway by kirsch equations based on the stope condition a numerical model was established to analyze the changes of stress displacement and plastic zones around roadways and the cause for roadway deformation during the mining of the upper coal seams the new support scheme was designed and applied at the study site the results show that the vertical stress the maximum shear stress and the plastic zones of the rock surrounding the roadway increase with the mining of the upper working faces roadway deformation and failure mainly occurs at floor sides and corners the key of roadway support was to control floor heave and then to recover the integrity and strength of the surrounding rock of two sides the developed omnidirectional rotatable drilling equipment can guarantee the success rate of floor drilling the broken surrounding rock of floor was enhanced through grouting the high prestress cable was used to support the roof and two sides and the birdcage cable was for the floor by the new support system the roadway deformation was controlled which could meet the support requirements

trace element and sulfur isotopic evidence for redox changes during formation of the wallaby gold deposit western australia abstract wallaby is a major gold deposit of the st ives gold field of western australia with an estimated resource of 8 million ounces of gold it has a well established paragenesis across five vein sets that displays macroscopic evidence of changing redox through time from hematite to magnetite micro analysis of pyrite from each vein generation shows a progressive and gradual change in redox conditions the sulfur isotope composition has a 34 s range of 7 7 to 9 8 using 3 m spots on the sensitive high resolution iron micro probe stable isotope shrimp si negative values indicative of an oxidized sulfur signature are found in the earliest generation of pyrite which coexists with hematite that also contains high concentrations of as ni zn ag sb cu and pb conversely positive values representative of reduced sulfur are found in later generations of pyrite with lower concentrations of as ni sb cu zn and pb these later pyrite crystals display higher as ni as sb and as bi and lower cu te these geochemical trends are the result of redox controlled transport and partitioning into pyrite of minor and trace elements now within the pyrite structure previous studies suggested a single orogenic event formed the wallaby deposit this is not supported by the present study trace element ratios such as as ni clearly delineate the high au generations and could be used as an exploration tool it is suggested that pyrite from the wallaby gold deposit formed via desulfidation and a gradual change in redox conditions within an evolving fluid and did not result from mixing of two separate fluids as previously advocated utilizing pyrite to link the entire fluid history of wallaby demonstrates the general use of pyrite as a valuable mineral tracer in gold bearing fluid systems

structural setting hydrothermal alteration and gold mineralisation at the archaean syenite hosted jupiter deposit yilgarn craton western australia the jupiter gold deposit in the northeastern eastern goldfields province of the yilgarn craton of western australia is hosted in greenschist facies metamorphosed tholeiitic basalt quartz alkali feldspar syenite and quartz feldspar porphyry syenite intrudes basalt as irregularly shaped dykes which radiate from a larger stock whereas at least three e w and ne sw striking quartz feldspar porphyries intrude both syenite and basalt brittle ductile shear zones are shallow dipping nw to ne striking or are steep dipping to the south and west quartz carbonate veins that host gold at jupiter occur in all lithologies and are divided into 1 veins that are restricted to the shear zones 2 discrete veins that are subparallel to shear zone hosted veins and 3 stockwork veins that form a network of randomly oriented microfractures in syenite wallrock proximal to shallow dipping shear zones the gold bearing veins comprise mainly quartz calcite ankerite and albite with minor sericite pyrite chalcopyrite galena sphalerite molybdenite telluride minerals and gold proximal hydrothermal alteration zones to the mineralised veins comprise quartz calcite ankerite albite and sericite high gold grades 2 g t au occur mainly in syenite and in the hanging walls to shallow dipping shear zones in syenite where there is a greater density of mineralised stockwork veins the jupiter deposit has structural and hydrothermal alteration styles that are similar to both granitoid hosted but post magmatic archaean lode gold deposits in the yilgarn craton and intrusion related syn magmatic syenite hosted gold deposits in the superior province of canada based on field observations and petrologic data the jupiter deposit is considered to be a post magmatic archaean lode gold deposit rather than a syn intrusion deposit

mining induced strata stress changes fractures and gas flow dynamics in multi seam longwall mining abstract this paper presents key findings from a recent comprehensive study of longwall mining induced strata movement stress changes fractures and gas flow dynamics in a deep underground coal mine in anhui china the study includes field monitoring of overburden displacement stress and water pressure changes at the longwall panel 1115 1 of the guqiao mine in addition 3d modelling of strata behaviour at the longwall panel using a 3d finite element code and goaf gas flow simulations with a cfd code are carried out this research has resulted in many new insights into the complex dynamic interaction between mining induced strata stress changes fractures and gas flow patterns based on the findings from the field monitoring and numerical modelling a three dimensional annular shaped overlying zone along the perimeter of the longwall panel is identified for optimal methane drainage during mining a practical method that helps define the geometry and boundary of this zone is proposed this study provides a new methodology and a set of engineering principles for the design of optimal co extraction of coal and methane

late archaean felsic alkaline igneous rocks in the eastern goldfields yilgarn craton western australia a result of lower crustal delamination numerous felsic alkaline intrusions were emplaced in the granite greenstone terrain of the eastern goldfields yilgarn craton between c 2650 and 2630 ma intrusion coincided with the waning stages of voluminous regional granitic magmatism the alkaline rocks are localized along and adjacent to major crustal structures that separate lithostratigraphic greenstone terranes and are divided into four geographically and compositionally distinct suites viz the mount monger emu claypan and ninnis suites the rocks have features in common with a type granites including high total alkalis an anhydrous primary mineralogy an apparent anorogenic setting and enrichment in some hfse although they also have low concentrations of nb and y they show a range of features that together point to a crustal source e g the alkaline rocks are not associated with voluminous mafic magmatism they have high lile concentrations they carry zircon xenocrysts of similar age to whole rock sm nd model ages they show evidence for regional source heterogeneity suites have constant and distinct la y and nb y ratios and the rocks show many compositional similarities to the slightly older voluminous crust derived granites extreme enrichments in sr and ba in the mount monger suite however suggests that their source may have been metasomatized before or during melting intrusion of the alkaline rocks heralds a poorly recognized third tectonothermal event in the evolution of the eastern part of the yilgarn craton and was broadly synchronous with the intrusion of voluminous felsic fractionated granites crustal extension and widespread au mineralization the late archaean geology of the eastern goldfields shows many features in common with phanerozoic collisional belts thought to be profoundly influenced by processes of lithospheric delamination or convective thinning this newly recognized third tectonothermal event in the eastern goldfields may relate to the delamination or convective thinning of a dense garnet rich lower crust that resulted from extraction of earlier voluminous granite magma and it is possible that such processes have had a greater influence on late archaean crustal evolution than previously recognized

near infrared spectral mapping of titan s mountains and channels 1 we investigate the spectral reflectance properties of channels and mountain ranges on titan using data from cassini s visual and infrared mapping spectrometer vims obtained during the t9 encounter 26 december 2005 we identify the location of channels and mountains using synthetic aperture radar maps obtained from cassini s radar instrument during the t13 30 april 2006 flyby channels are evident even in vims imaging with spatial resolution coarser than the channel size the channels share spectral characteristics with titan s dark blue terrain e g the huygens landing site that is consistent with an enhancement in water ice content relative to the rest of titan we use this fact to measure widths of 1 km for the largest channels comparison of the data sets shows that in our study area within the equatorial bright spectral unit east of xanadu mountains are darker and bluer than surrounding smooth terrain these results are consistent with the equatorial bright terrain possessing a veneer of material that is thinner in the regions where there are mountains and streambeds that have likely undergone more recent and extensive erosion we suggest a model for the geographic relationship of the dark blue dark brown and equatorial bright spectral units based on our findings

porphyry gold copper mineralisation in the cadia district eastern lachlan fold belt new south wales and its relationship to shoshonitic magmatism the cadia porphyry gold copper district is the largest hydrothermal intrusion related gold deposit in eastern australia discovered in 1992 by newcrest mining limited pre mine resources in the district were in excess of 585 t au and 2 35 mt cu the cadia district lies within shoshonitic subaqueous volcanic rocks of the late ordovician molong volcanic belt in the eastern lachlan fold belt lfb of new south wales an island arc tectonic setting is envisaged for the formation of these volcanic rocks but the nature of the arc basement and geometry of the subduction zone s is debated mineralisation occurs in four principal porphyry deposits cadia hill cadia ridgeway cadia east cadia far east and cadia quarry as sheeted and stockwork quartz sulfide veins and locally as broadly stratabound disseminated mineralisation cadia east and skarn big cadia and little cadia all of the porphyry deposits show a close spatial association with shoshonitic monzodiorite to quartz monzonite dykes and stocks of the cadia intrusive complex cic gold copper mineralisation is hosted by these intrusions and also by the enclosing forest reefs volcanics frv wall rocks hydrothermal alteration associated with mineralisation is potassic which is overprinted by selectively pervasive propylitic and silica albite assemblages petrological studies and major and trace element analysis of rocks of the cic and frv as well as of other intrusions in the cadia district that appear unrelated to mineralisation have been conducted unaltered samples from the cic are characterised by high k2o contents up to 6 5 wt and molecular k na ratios consistently 1 confirming the alkalic and shoshonitic nature of the complex the cic samples also fall just within the shoshonite field on ce yb ta yb and th yb ta yb plots although immediately adjacent to the calc alkaline field the frv are geochemically similar to the cic although lower in p2o5 and ce lree dacitic and hornblende porphyry intrusions from within the district but spatially unrelated to mineralisation have a distinctive geochemical signature and are not shoshonitic in composition the close spatial association between gold copper mineralisation and the shoshonitic monzonitic cic argues strongly for a genetic link between the two a similar association occurs at the economic goonumbla porphyry gold copper deposits in the eastern lfb while sub economic gold copper mineralisation at cargo and copper hill is associated with calc alkaline quartz diorite and dacitic intrusions the cadia district is considered to be an excellent example of the association of alkaline potassic magmas and gold copper porphyry style mineralisation

genesis and exploration implications of epithermal gold mineralization and porphyry style alteration at the endeavour 41 prospect cowal district new south wales australia endeavour 41 is a deep level structurally controlled epithermal gold deposit hosted by early ordovician subaqueous volcanosedimentary rocks calc alkalic to shoshonitic mafic to intermediate sills dikes and stocks intruded the volcanosedimentary units in the middle ordovician the most felsic intrusions together with pyroxene bearing dikes are temporally related to gold mineralization postmineralization intrusions are exclusively of mafic character endeavour 41 evolved from early high temperature porphyry style veins and alteration to lower temperature epithermal style gold mineralization early magnetite and garnet bearing veins stage 1 and 2 respectively associated with actinolite magnetite and biotite bearing alteration assemblages have been cut by gold bearing veins and associated alteration assemblages there were two main epithermal style gold mineralizing events 1 quartz pyrite calcite adularia chlorite veins stage 3 and 2 carbonate base metal sulfide veins calcite ankerite quartz pyrite sphalerite galena chalcopyrite ag tellurides arsenopyrite apatite hematite illite muscovite and chlorite stage 4 gold occurs principally as a refractory phase in pyrite it also occurs as grains of au ag tellurides and as inclusions of free gold in pyrite sphalerite and chalcopyrite hydrothermal alteration associated with gold mineralized veins produced early epidote and k feldspar epidote bearing alteration halos and later stage illite muscovite k feldspar and calcite rich alteration halos the highest gold grades are associated with muscovite and illite alteration stable isotope analyses and fluid inclusion data provide evidence of a magmatic hydrothermal component to the mineralizing fluids fluid inclusion data suggest that gold precipitated from boiling saline waters 9 0 wt nacl at temperatures of about 310 c stage 3 veins are estimated to have formed approximately 1 km below the paleosurface at hydrostatic pressure 90 bars stage 4 illite formed at temperatures below 280 c stage 3 calcite has 13 c calcite and 18 o calcite values that range from 5 2 to 4 6 and from 11 6 to 12 1 respectively calculated fluids for these mineral values at 300 c 13 c fluid 3 18 o fluid 6 are consistent with a magmatic hydrothermal source of carbon and oxygen during stage 3 a component of meteoric waters is inferred for stage 4 because 13 c carbonate and 18 o carbonate values range from 6 9 to 0 5 and from 10 9 to 30 1 respectively corresponding to 13 c fluid and 18 o fluid values of 5 and 2 at 200 to 250 c the 34 s sulfide values for early vein stages range between 4 9 and 0 5 stage 3 has 34 s sulfide values ranging from 5 2 to 0 8 with the most 34 s enriched values deposited away from the mineralized center stage 4 sulfides have isotopic compositions from 7 5 to 2 5 the negative isotopic values are consistent with oxidized sulfate predominant magmatic hydrothermal fluids sulfur isotopic zonation patterns show that the most negative 34 s values correlate with gold enriched domains and also with areas that contain high temperature porphyry style alteration facies the negative sulfur isotope values define zones of upflow for the mineralizing magmatic hydrothermal fluids the paragenetic history of endeavour 41 records a transition from deep level to shallow level magmatic hydrothermal activity this transition implies erosion and unroofing of the system synchronous with mineralization high temperature assemblages e g actinolite magnetite biotite and k feldspar epidote indicate that epithermal mineralization occurred proximal to a magmatic hydrothermal center and that there is potential for the discovery of porphyry copper gold mineralization below the current level of diamond drilling

archean high mg monzodiorite syenite epidote skarn and biotite sericite gold lodes in the granny smith wallaby district australia u pb and re os chronometry of two intrusion related hydrothermal systems the granny smith 37 t au production and wallaby deposits 38 t out of a 180 t au resource are located northeast of kalgoorlie in 2 7 ga greenstones of the eastern goldfields province the youngest orogenic belt of the yilgarn craton western australia at granny smith a zoned monzodiorite granodiorite stock dated by a concordant titanite zircon u pb age of 2 665 3 ma cuts across east dipping thrust faults the stock is fractured but not displaced and sets a minimum age for large scale 1 km thrust faulting d2 regional folding d1 and dynamothermal metamorphism in the mining district the local gold pyrite mineralization controlled by fractured fault zones is younger than 2 665 3 ma in augite hornblende monzodiorite alteration progressed from a hematite stained alkali feldspar quartz calcite assemblage and quartz molybdenite pyrite veins to a late reduced sericite dolomite albite assemblage gold related monazite and xenotime define a u pb age of 2 660 5 ma and molybdenite from veins a re os isochron age of 2 661 6 ma indicating that mineralization took place shortly after the emplacement of the main stock perhaps coincident with the intrusion of late alkali granite dikes at wallaby a ne trending swarm of porphyry dikes comprising augite monzonite monzodiorite and minor kersantite intrudes folded and thrust faulted molasse the conglomerate and the dikes are overprinted by barren 1 600 m long replacement pipe which is intruded by a younger ring dike of syenite porphyry pervasively altered to muscovite calcite pyrite skarn and syenite are cut by pink biotite calcite veins containing magnetite pyrite and subeconomic gold silver mineralization au ag 0 2 the veins are associated with red biotite sericite calcite albite alteration in adjacent monzonite dikes structural relations and the concordant titanite u pb age of the skarn constrain intrusion related mineralization to 2 662 3 ma the main stage gold pyrite ore au ag 10 forms hematite stained sericite dolomite albite lodes in stacked d2 reverse faults which offset skarn syenite and the biotite calcite veins by up to 25 m the molybdenite re os age 2 661 10 ma of the ore suggests a genetic link to intrusive activity but is in apparent conflict with a monazite xenotime u pb age 2 651 6 ma which differs from that of the skarn at the 95 confidence level the time relationships at both gold deposits are inconsistent with orogenic models invoking a principal role for metamorphic fluids released during the main phase of compression in the fold belt instead mineralization is related in space and time to late orogenic magnetite series high mg monzodiorite syenite intrusions of mantle origin characterized by mg mg fetotal 0 31 0 57 high cr 34 96 ppm ni 22 63 ppm ba 1 056 2 321 ppm sr 1 268 2 457 ppm th 15 36 ppm and rare earth elements total ree 343 523 ppm at wallaby shared ca k co2 metasomatism and th ree enrichment in allanite link au ag mineralization in biotite calcite veins to the formation of the giant epidote skarn implicating a th ree rich syenite pluton at depth as the source of the oxidized hydrothermal fluid at granny smith lead isotope data and the rb th u signature of early hematite bearing wall rock alteration point to fluid released by the source pluton of the differentiated alkali granite dikes

smoothness of titan s ontario lacus constraints from cassini radar specular reflection data 1 cassini radar altimetry data collected on the 49th flyby of titan 2008 december 21 over ontario lacus in titan s south polar region provides strong evidence for an extremely smooth surface with less than 3 mm rms surface height variation over the 100m wide fresnel zone histograms of the raw radar echoes imply a mirror like specular reflection of the transmitted signal such an echo is possible only if the surface is extremely flat relative to our 2 2 cm wavelength the 3 mm upper bound follows from analyzing the strength of the specular return which declines exponentially with increasing surface height variance in this experiment the strength of the echo was larger than expected severely saturating the receiver we developed a method to partially correct the echoes for the distortion incurred while the implied mm scale smoothness is not proof that the surface is liquid it is unlikely that a solid surface is so smooth

geology and district scale setting of tilted alkalic porphyry cu au mineralization at the lorraine deposit british columbia lorraine is a copper gold porphyry deposit 6 4 mt indicated resource at 0 61 copper and 0 23 g t gold and 28 8 mt inferred resource at 0 45 copper and 0 19 g t gold in north central british columbia one of the youngest known alkalic porphyry deposits within the triassic jurassic quesnel arc the deposit is hosted by the early jurassic duckling creek syenite complex an alkalic multiphase intrusive dike complex of pyroxenite syenite and monzonite composition the southern part of the complex hosts numerous copper gold porphyry prospects in addition to lorraine together they constitute the duckling creek district main stage cu au porphyry mineralization at lorraine is hosted by phase 1 of the duckling creek syenite complex an sw dipping early intrusive suite of silica undersaturated pyroxenites and syenites mineralized zones are up to 2 5 km long by 500 m wide in the form of northwesterly elongate sw dipping panels that generally parallel the phase 1 intrusive contacts mineralization is attributed to blind porphyries within the phase 1 sequence which was tilted after main stage mineralization copper sulfides define deposit scale zonation patterns of bornite chalcocite cores rimmed by chalcopyrite rich and outer weakly developed pyrite dominated domains alteration patterns and intensity are consistent across mineralized zones strong pervasive k feldspar biotite potassic core zones are rimmed by albite diopside magnetite calc potassic alteration that is pervasive near the center of the zones but varies laterally outward to vein style alteration pervasive albite alteration sodic is locally present and is interpreted to be an early alteration event mineralization at lorraine has been cut by later phases of the duckling creek syenite complex a second cycle of pyroxenite syenite monzonite intrusion phase 2 is mineralogically similar to phase 1 but is unmineralized and has vertical intrusive contacts that strike northwest a change to late silica saturated intrusions is marked by subvertical phase 3 silica saturated leucosyenite and pegmatite dikes u pb zircon and ar ar geochronology constrain the timing of main stage mineralization at lorraine to an approximately 1 5 m y interval between 180 ma and 178 5 ma phase 1 intrusions are as old as 181 68 0 95 ma based on an ar ar age on biotite from pyroxenite but may range to as young as 180 2 0 28 ma based on a u pb zircon age from a mineralized phase 1 syenite the upper age limit for mineralization is 178 75 0 21 ma based on u pb data for a postmineral phase 2 syenite an alternate interpretation considers the presence of zircon antecrysts in an analyzed phase 1 rock which leads to a more narrow time window of 0 31 m y that includes phase 1 intrusion main stage porphyry mineralization and structural tilting which was followed by phase 2 intrusion magmatic and hydrothermal activity in the lorraine area persisted until at least 176 ma based on the u pb zircon age of 176 77 0 36 ma from a phase 3 leucosyenite dike and a late biotite albite apatite vein with an ar ar biotite age of 175 21 0 91 ma several intrusive hosted porphyry prospects within the duckling creek district share mineralogical and alteration characteristics as well as relative igneous paragenesis with lorraine the model for magmatic and hydrothermal development at lorraine may broadly be applied to the district as a whole providing a geologic framework upon which to base future exploration in the district

fluid inclusion and stable isotope o h c constraints on the genesis of the pedra branca gold deposit troia massif borborema province ne brazil an example of hypozonal orogenic gold mineralization abstract at the archean paleoproterozoic troia massif ne brazil two major paleoproterozoic greenstone belts are documented algodoes and serra das pipocas they share similar lithostratigraphic characteristics with other 2 2 2 1 ga greenstone belts of the surrounding cratonic domains e g guiana shield and west africa craton gold mineralization in the serra das pipocas greenstone belt is associated with a regional ne trending shear zone in the mineralized area the pedra branca gold deposit the main gold mineralization is found in association with quartz veins calc silicate alteration e g diopside k feldspar amphibole titanite biotite pyrite albite magnetite carbonates and albitization pyrrhotite is commonly found as inclusions in pyrite and late magnetite replaces pyrite suggesting progressive oxidation of the ore forming fluid free milling gold commonly precipitates at the late stages of alteration in close association with magnetite and tellurides the main tellurides found are hessite altaite sylvanite calaverite and tellurobismuthite two fluid inclusion assemblages were identified from mineralized quartz veins assemblage 1 is characterized by pseudo secondary trails that show the coexistence of co2 rich and low salinity 0 8 wt nacl equiv co2 h2o nacl and h2o nacl inclusions suggesting formation during phase separation fluid immiscibility assemblage 2 is represented by late secondary low temperature th

europa ganymede and callisto new radar results from arecibo and goldstone observations of the icy galilean satellites conducted during 1987 1991 with the arecibo 13 cm system and the goldstone 3 5 cm system yield significant improvements in our knowledge of the satellites radar properties hardly any wavelength dependence is seen for either the total power radar albedo or the circular polarization ratio c for europa ganymede and callisto our 13 cm estimates of mean values and rms dispersions are 1 39 0 14 and 0 69 0 06 and c 1 53 0 03 1 43 0 06 and 1 17 0 04 radar albedo features are seen on each satellite evidence for c features is lacking except for indications of a weak hemispheric asymmetry for callisto that intersatellite and intrasatellite fractional variations in albedo greatly exceed variations in c is consistent with predictions of coherent backscatter theory and implies that albedo might be a crude indicator of relative silicate abundance the satellites albedo distributions overlap the most prominent radar features are tentatively identified with galileo regio and the valhalla basin estimates of echo doppler frequencies show callisto to be lagging its ephemeris by 200 50 km

an experimental and numerical investigation on the deformation of overlying coal seams above double seam extraction for controlling coal mine methane emissions abstract this study investigates the deformation and the resultant pressure relief of highly gassy coal seams where a double seam mining operation takes place at lower depths at the wulan coal mine china in order to predict the depressurization effect in the overlying coal seams we simulate the extraction process by constructing a scaled model in the laboratory using similar rock materials analyses of experimental results concluded that due to the mining induced stress redistribution the pressure within target coal seams which were 109 m above the mined seams could be fully relieved to attain the statutory approval for gas drainage in addition to scaled model studies computational modeling studies were conducted using udec universal distinct element code which showed that the features of deformation resulting from the double seam extraction were different from that of in the case of single seam extraction the results of the numerical studies revealed that in addition to the panel margin on the air return side areas near the intake entry could also be considered as borehole drilling positions besides it was found that the gob of the extracted seams below the gassy one provided a buffering effect for the would mined protective coal seam and that the depressurization effect was largely weakened the laboratorial findings are instructive to the field practice of methane drainage during the mining operation a displacement comparison method was adopted to measure the dilated amount of protected coal seams and as expected the maximum dilation percentage was much more than 0 2 the critical value upon which the target coal seam is appropriately depressurized to allow gas drainage to be safely and effectively implemented

the lakes of titan the surface of saturn s haze shrouded moon titan has long been proposed to have oceans or lakes on the basis of the stability of liquid methane at the surface1 2 initial visible3 and radar4 5 imaging failed to find any evidence of an ocean although abundant evidence was found that flowing liquids have existed on the surface5 6 here we provide definitive evidence for the presence of lakes on the surface of titan obtained during the cassini radar flyby of titan on 22 july 2006 t16 the radar imaging polewards of 70 north shows more than 75 circular to irregular radar dark patches in a region where liquid methane and ethane are expected to be abundant and stable on the surface2 7 the radar dark patches are interpreted as lakes on the basis of their very low radar reflectivity and morphological similarities to lakes including associated channels and location in topographic depressions some of the lakes do not completely fill the depressions in which they lie and apparently dry depressions are present we interpret this to indicate that lakes are present in a number of states including partly dry and liquid filled these northern hemisphere lakes constitute the strongest evidence yet that a condensable liquid hydrological cycle is active in titan s surface and atmosphere in which the lakes are filled through rainfall and or intersection with the subsurface liquid methane table

global scale surface spectral variations on titan seen from cassini vims we present global scale maps of titan from the visual and infrared mapping spectrometer vims instrument on cassini we map at 64 near infrared wavelengths simultaneously covering the atmospheric windows at 0 94 1 08 1 28 1 6 2 0 2 8 and 5 m with a typical resolution of 50 km pixel or a typical total integration time of 1 s our maps have five to ten times the resolution of ground based maps better spectral resolution across most windows coverage in multiple atmospheric windows and represent the first spatially resolved maps of titan at 5 m the vims maps provide context and surface spectral information in support of other cassini instruments we note a strong latitudinal dependence in the spectral character of titan s surface and partition the surface into 9 spectral units that we describe in terms of spectral and spatial characteristics

spatially resolved images of titan by means of adaptive optics abstract images of titan were acquired with the adonis adaptive optics system installed at the eso 3 6 m telescope in la silla chile the near infrared range from 1 2 5 m was covered in 1994 and 1995 in the methane atmospheric windows at 1 3 1 6 and 2 0 m with narrow band filters and cvf diffraction limited images were obtained 0 14 arcsec at 2 m thus allowing us to resolve the titan disk we have corrected the images for systematic effects removed center to limb variation and applied deconvolution processes to our data the contrast on the images is on the order of 30 both the leading and trailing hemispheres were observed the 2 m images presented in this paper show a broad bright feature on the surface of titan s leading hemisphere near 114 lcm which is in agreement with the hst images and with spectroscopy performed at these longitudes from the ground that show a higher geometric albedo on titan s leading side high quality flat fielding of our data has highlighted the presence of at least two main bright spots within the equatorial region the trailing hemisphere of titan s surface is not completely dark but shows brightness near the poles with some north to south asymmetry the northern latitudes are uniformly brighter than the lower equatorial and southern latitudes factor of about 2 our results bring new constraints on the models of the satellite s surface

titan and other icy satellites dielectric properties of constituent materials and implications for radar sounding abstract a number of scientific problems concerning titan and the other icy satellites of the outer solar system could be addressed by the technique of radar sounding we consider the materials present on and within these bodies model their dielectric properties and evaluate the extent to which radar signals can penetrate through them the primary materials of interest are h2o ice h2 nh3 solution simple and polymeric organic solids and ch4 c2h6 n2 liquid plus its minor organic and inorganic solutes penetration through h2o ice is limited by multiple scattering and by the long wavelength wing of the submillimeter band deep penetration is possible at long wavelengths and strong reflections could result from pockets or layers of subsurface h2o nh3 solution the dielectric constant of a putative ch4 c2h6 n2 ocean on titan is 1 65 1 81 depending on ch4 content and optical depth 40 to 200 cm 2 for depths of 0 75 to 7 km we estimate that dissolved species especially ch3cn hcn and h2o can increase the absorption by at least a factor of 2 but the effects of these polar solutes are very difficult to predict without direct experimental investigation and could be much greater sediment is composed of simple solids 2 0 2 4 and organic hetero polymers 4 5 5 5 with negligible radar attenuation to investigate a specific case of interest we consider radar observations of titan using the sounding mode of the cassini radar experiment we use our models to calculate radar signal noise ratios for reflections from titan the surface of titan is modeled as consisting of h2o ice covered by a 100 m thick layer of organic sediments overlain in turn by an ocean of liquid ch4 c2h6 n2 only reflections from the surface of the ocean in this model would be observed at a radar wavelength of 2 2 cm but at 13 6 cm we compute signal noise exceeding 10 db from the ocean sediment and sediment ice interfaces hence such a sounding mode may offer prospects for investigating the geology of titan even if the surface of the satellite is covered locally or globally by a deep ocean

geotechnical assessments of the stability of slopes at the cakmakkaya and damar open pit mines turkey a case study the on site observations monitoring data and results of back analyses of failures showed that large scale failures occurred along both the interconnected sliding surfaces consisting of a discontinuities in the dacites and the contact zone and b the circular surfaces through the weathered soil like dacites at the cakmakkaya and damar open pit mines surface water infiltration through the weathered soil like material after a short duration of rainfall contributed to the circular shaped failures after a heavy rainy period an increase in the groundwater table above the contact zone played a major role in the initiation of bi planar wedge failures in addition the stability of the slopes is likely to have been controlled by the orientation of this zone the results of back analyses indicated that the shear strengths of the soil like materials in the weathered dacites and the contact zone had reduced to their residual values at the time of initial sliding the flattening of the slope angles with an effective surface drainage and long term monitoring of the groundwater level is proposed as the most suitable remedial measure

cassini radar views the surface of titan the cassini titan radar mapper imaged about 1 of titan s surface at a resolution of 0 5 kilometer and larger areas of the globe in lower resolution modes the images reveal a complex surface with areas of low relief and a variety of geologic features suggestive of dome like volcanic constructs flows and sinuous channels the surface appears to be young with few impact craters scattering and dielectric properties are consistent with porous ice or organics dark patches in the radar images show high brightness temperatures and high emissivity and are consistent with frozen hydrocarbons

space time patterns of magmatism along the tethysides a preliminary study five maps showing spatio temporal evolution of magmatism along the tethysides for the following time intervals late carboniferous and permian 320 248 ma triassic and early jurassic 247 188 ma

the world class wallaby gold deposit laverton western australia an orogenic style overprint on a magmatic hydrothermal magnetite calcite alteration pipe gold mineralisation at the wallaby gold deposit is hosted by a 1 200 m thick mafic conglomerate the conglomerate is intruded by an apparently comagmatic alkaline dyke suite displaying increasing fractionation through mafic monzonite monzonite syenite syenite porphyry to late stage carbonatite in the mine area a pipe shaped zone of actinolite magnetite epidote calcite amec alteration overprints the conglomerate gold mineralisation associated with dolomite albite quartz pyrite alteration is hosted in a series of sub horizontal structurally controlled zones that are largely confined within the magnetite rich pipe the deposit has a current ore reserve of 2 0 moz au and a total resource of 7 1 moz au

some metallogenic features of gold and copper deposits related to alkaline rocks and consequences for exploration porphyry copper gold skarn copper gold sediment hosted carlin style gold breccia pipe low sulphidation epithermal gold pluton related mesothermal or orogenic gold vein and volcanogenic massive sulphide deposits associated with alkaline rocks are commonly broadly similar to those hosted by their calc alkaline counterparts in contrast porphyry molybdenum gold deposits are confined to alkaline igneous centres alkaline suites are notably deficient in high sulphidation epithermal gold deposits and even in the advanced argillic lithocaps which host them this is surprising given that the required oxidised sulphur species are seemingly more abundant than in calc alkaline igneous centres highly efficient buffering of acidic fluid by metasomatised alkaline rocks may offer a viable explanation all types of intrusion related zinc deposits also appear to be poorly developed in alkaline provinces the characteristics of several gold and copper deposits associated with alkaline rocks including the giant porgera cripple creek ladolam olympic dam and phalaborwa examples are judged to diverge appreciably from their most closely related deposit types rendering them arguably unique most of these aberrant mineralisation styles may be due to variations in magmatic fluid compositional and liberation characteristics consequent upon the extreme diversity of ore related alkaline magmas most types of gold and copper deposits developed in calc alkaline provinces also constitute exploration targets in and around alkaline igneous centres although porphyry copper gold and low sulphidation epithermal gold deposits are considered to possess the greatest potential perhaps of even greater interest however is the possibility of encountering unconventional giant gold and copper deposits which lack closely analogous examples if already defined aberrant deposits are truly unique then exploration designed specifically to detect additional examples is pointless furthermore exploration for new unique deposits is difficult because their defining geological parameters are unknown alkaline rocks within or behind calc alkaline arcs at convergent plate boundaries probably offer the greatest exploration potential although anorogenic intracontinental extensional settings should not be ignored

physical modelling of subsidence from sequential extraction of partially overlapping longwall panels and study of substrata movement characteristics field examples of subsidence from sequential extraction of overlapping coal longwall panels have shown that complex and unexpected subsidence effects can occur physical models comprising sand and plaster obeying relevant similarity rules were used to investigate the subsidence mechanisms displacements within the models were measured using a combination of optical transducers photogrammetry and laser scanning the observed results were compared with finite element models the models demonstrate that the incremental subsidence and substrata movement profiles after lower seam extraction can be separated into three different zones these zones undergo different horizontal and vertical movement characteristics the zone of overlap of the two longwall panels undergoes greater total subsidence compared to a single seam of equivalent thickness the limit angle of the subsidence also differs at the two ends of the lower extraction as a result of the effects of the previously mined out area above

archean gold mineralization in an intrusion related geochemically zoned district scale alteration system in the carosue basin western australia the carosue basin in the eastern goldfields of the archean yilgarn craton western australia is a late stage syntectonic sequence of feldspathic volcaniclastic sedimentary rocks that unconformably overlies deformed greenstones it was intruded by a suite of monzonitic syenitic and lamprophyric magmas that form numerous plugs and dikes within the carosue basin the intrusions are most voluminous at carosue dam where the basin and underlying greenstones are cut by a swarm of north south trending faults a large hydrothermal alteration system several kilometers wide and at least 10 km long is centered on this area zones of sodic albite and potassic biotite alteration are enveloped sequentially by phyllic muscovite and propylitic chlorite alteration a central zone of anomalous bi w mo cu pb ag enrichment is enveloped by a zone of relative zn and as enrichment more or less coincident with the muscovite alteration zone the district scale potassic alteration is attributed to magmatic fluids derived from the intermediate to felsic intrusions the origin of the sodic alteration is uncertain but could be attributed to a magmatic fluid or a mesothermal orogenic fluid two styles of gold mineralization are present within the carosue dam area both types are associated with north south faults the most common type karari type mineralization is best developed in the sodic and potassic alteration zones and is further associated with subvolcanic intrusions disseminated hematite in sodic alteration zones and disseminated pyrite there is a poor correlation between gold grades and quartz carbonate veins the second style of mineralization represented by the twin peaks deposit occurs in a sequence of more mature siliciclastic metasedimentary rocks that lie just outside the carosue basin within the district scale muscovite alteration zone intrusions and hematite are volumetrically minor or absent at twin peaks gold occurs in quartz carbonate veins and is associated with intense carbonate alteration and arsenopyrite the carosue dam district represents an important example of a large archean intrusion related hydrothermal system with contrasting styles of associated gold mineralization the origin of karari and other deposits of this class is equivocal and could be related to magmatic fluids or reaction of a mesothermal orogenic fluid with feldspar rich host rocks twin peaks is an example of an orogenic gold deposit that has been superimposed on the distal parts of the intrusion related alteration system

field measurement and failure forecast during the remediation of a failed cut slope a large number of deep cuts are formed during the construction of expressways in mountainous areas inadequate interpretation of ground conditions is a major contributing factor to the failure of cut slopes this study focuses on the hongyan landslide along the s26 expressway due to lack of an adequate pre construction investigation a landslide was triggered by small scale excavation at the toe part of the slope the potential slip surface was incorrectly located consequently two rows of stabilizing piles were not long enough to reach stable rocks to overcome the mistake two additional rows of piles were installed during construction both slope deformation and the stress of reinforced bars in piles were monitored for safety considerations a verhulst model based failure forecast was also utilized to insure the stability of the slope during remedial works reviewing this landslide reveals a number of lessons first sufficient geological investigation and careful interpretation of ground conditions are mandatory prior to the design of a cut slope second systematic field monitoring is strongly recommended especially when the geology of the slope is complex and it is difficult to determine failure patterns third the failure forecast can serve as a supplementary measure to insure the safety of workers and slopes last it always takes some time for stabilizing piles to mobilize

gold deposits of the northern margin of the north china craton multiple late paleozoic mesozoic mineralizing events the northern margin of the north china craton is well endowed with lode gold deposits hosting a resource of approximately 900 tonnes t of gold the 1 500 km long region is characterized by east trending blocks of metamorphosed archean and proterozoic strata that were episodically uplifted during variscan indosinian and yanshanian deformational and magmatic events at least 12 gold deposits from the daqinshan yan liao includes the zhangjiakou yanshan and chifeng gold districts and changbaishan gold provinces contain resources of 20 100 t au each most deposits are hosted in uplifted blocks of precambrian metamorphic rocks although felsic paleozoic and mesozoic plutons are typically proximal and host 30 of the deposits the lodes are characterized by sulfide poor quartz veins in brittle structures with low base metal values and high au ag ratios although phyllic alteration is most common intensive alkali feldspar metasomatism characterizes the wulashan dongping and zhongshangou deposits but is apparently coeval with variscan alkalic magmatism only at wulashan stepwise 40ar 39ar geochronology on 16 samples from gangue and alteration phases combined with unpublished shrimp u pb dates on associated granitoids suggest that gold mineralizing events occurred during variscan indosinian and yanshanian orogenies at circa 350 250 200 180 150 and 129 ma however widespread permo triassic 250 ma and early jurassic 180 ma thermal events caused variable resetting of most of the white mica and k feldspar argon spectra as well as previously reported k ar determinations compiled and new stable isotope and fluid inclusion data show that most 18o values for ore stage veins range from 8 to 14 indicating a fluid in equilibrium with the precambrian metamorphic basement rocks d values from fluid inclusions range widely from 64 to 154 which is indicative of a local meteoric component in some veins and highly variable 34s data 7 to 17 even within individual deposits indicate various local country rock sources for sulfur fluid inclusions from all districts show variable homogenization temperatures between 240 and 400 c and are consistently characterized by low salinity h2o co2 ch4 n2 solutions although the data are largely consistent with that from orogenic gold veins intrusion related veins and epithermal veins are also recognized the multiple episodes of mineralization are coincident with episodic tectonic reactivations and associated magmatism along the northern margin of the north china craton electronic supplementary material to this paper can be obtained by using the springer link server located at http dx doi org 10 1007 s00126 001 0239 2

cassini radar observations of enceladus tethys dione rhea iapetus hyperion and phoebe cassini 2 2 cm radar and radiometric observations of seven of saturn s icy satellites yield properties that apparently are dominated by subsurface volume scattering and are similar to those of the icy galilean satellites average radar albedos decrease in the order enceladus tethys hyperion rhea dione iapetus and phoebe this sequence most likely corresponds to increasing contamination of near surface water ice which is intrinsically very transparent at radio wavelengths plausible candidates for contaminants include ammonia silicates metallic oxides and polar organics ranging from nitriles like hcn to complex tholins there is correlation of our targets radar and optical albedos probably due to variations in the concentration of optically dark contaminants in near surface water ice and the resulting variable attenuation of the high order multiple scattering responsible for high radar albedos our highest radar albedos for enceladus and tethys probably require that at least the uppermost one to several decimeters of the surface be extremely clean water ice regolith that is structurally complex i e mature enough for there to be high order multiple scattering within it at the other extreme phoebe has an asteroidal radar reflectivity that may be due to a combination of single and volume scattering iapetus 2 2 cm radar albedo is dramatically higher on the optically bright trailing side than the optically dark leading side whereas 13 cm results reported by black et al black g j campbell d b carter l m ostro s j 2004 science 304 553 show hardly any hemispheric asymmetry and give a mean radar reflectivity several times lower than the reflectivity measured at 2 2 cm these iapetus results are understandable if ammonia is much less abundant on both sides within the upper one to several decimeters than at greater depths and if the leading side s optically dark contaminant is present to depths of at least one to several decimeters as argued by lanzerotti et al lanzerotti l j brown w l marcantonio k j johnson r e 1984 nature 312 139 140 a combination of ion erosion and micrometeoroid gardening may have depleted ammonia from the surfaces of saturn s icy satellites given the hypersensitivity of water ice s absorption length to ammonia concentration an increase in ammonia with depth could allow efficient 2 2 cm scattering from within the top one to several decimeters while attenuating 13 cm echoes which would require a six fold thicker scattering layer if so we would expect each of the icy satellites average radar albedos to be higher at 2 2 cm than at 13 cm as is the case so far with rhea black g campbell d 2004 bull am astron soc 36 1123 as well as iapetus

mechanism of strata deformation under protective seam and its application for relieved methane control abstract in this paper an equation correlated with normal stress and permeability was developed and flac3d software was used to investigate the rock mass stress evolution and distribution to understand the methane flow characteristics research results show that the rock mass under the protective coal seam can be divided into three belts zones in the vertical direction including total de stressed belt vertical de stressed belt and original stress belt methane in the total de stressed belt can flow into the working face of protective coal seam by its own pressure gradient methane in the vertical de stressed belt can only be extracted by boreholes in the horizontal direction the rock mass was also divided into five zones including original zone compression zone expansion zone recovering zone and re compacted zone which have been proved correct by the field experiments the rock mass permeability in the de stressed belts doesn t increase until stepping into the expansion zone and from then on higher concentration of methane can be extracted the methane in original regions is difficult to extract because rock stresses stay the same the division of three belts and five zones reveals the rock mass stress and permeability distribution and evolution and supplies theoretical guidance for relieved methane control

ground based radar observations of titan 2000 2008 abstract we have observed titan with the arecibo observatory s 12 6 cm wavelength radar system during the last eight oppositions of the saturn system with sufficient sensitivity to characterize its scattering properties as a function of sub earth longitude in a few sessions the green bank telescope was used as the receiving instrument in a bistatic configuration to boost sub radar track length and integration time radar echo spectra have been obtained for a total of 92 viewing geometries with sub earth locations scattered through all longitudes and at latitudes between 7 6 s and 26 3 s close to the maximum southern excursion of the sub earth track we find titan to have globally average radar albedos at this wavelength of 0 161 in the opposite circular polarization sense as that transmitted oc and 0 074 in the same sense sc giving a polarization ratio sc oc of 0 46 these values are intermediate between lower reflectivity rocky surfaces and higher reflectivity clean icy surfaces the variations with longitude in general mirror the surface brightness variations seen through the infrared atmospheric windows xanadu regio s radar reflectivity and polarization ratio are higher than the global averages and suggest that its composition is relatively cleaner water ice or possibly some other material with low propagation loss at radio wavelengths for all echo spectra most of the power is in a broad diffuse component but with a specular component whose strength and narrowness is highly variable as a function of surface location for all data we fit a sum of the standard hagfors scattering law describing the specular component and an empirical diffuse radar scattering model to extract bulk parameters of the surface many areas exhibit very narrow specular reflections implying terrain that are quite flat on centimeter to meter scales over spans of tens to perhaps hundreds of kilometers the proportion of spectra showing these narrow specular echoes has fallen significantly over the observational time span indicating either a latitudinal effect related to terrain differences or changing surface conditions over the past several years a few radar tracks especially those from the 2008 session overlap some high resolution cassini radar imagery swaths to allow a direct comparison with terrain

the tectonic setting and evolution of the 2 7 ga kalgoorlie kurnalpi rift a world class archean gold province the yilgarn craton results from three major mantle input events at ca 3 0 2 9 2 8 and 2 7 ga that have interacted with 3 0 ga continental crust zircon geochronology and sm nd isotopic data subdivide the craton into an older yilgarn proto craton and the younger more primitive eastern goldfields superterrane egst formation of the kalgoorlie kurnalpi rift kkr within the egst was associated with the 2 7 ga event which exploited weakened crust at the eastern margin of the yilgarn proto craton where thick sequences of komatiite and basalt were erupted between ca 2710 and 2690 ma in the kalgoorlie terrane calc alkaline volcanism in the kurnalpi terrane began at ca 2730 ma and continued to ca 2690 ma overlapping rifting and plume related volcanism in the kalgoorlie terrane deposition of siliciclastic sedimentary rocks within basins at ca 2660 resulted from an intra orogenic extensional event and coincided with the transition from high ca to low ca granite magmatism and peak emplacement of intrusions with a metasomatised mantle source component most aspects of the kkr are satisfied by broadly coincident plume related magmatism in the kalgoorlie terrane and westward subduction to the east of the burtville terrane geochemical characteristics of 2730 2700 ma calc alkaline volcanism and 2685 2630 ma low sio2 and alkali rich intrusions support models for a continental margin subduction zone setting world class gold deposits formed in reactivated margins of the kkr which became flux zones for mantle derived magmas hydrothermal fluids and heat during 2675 2620 ma orogenesis the orogenic gold mineralisation can be subdivided into proximal intrusion related and distal source deposits

dunes on titan observed by cassini radar thousands of longitudinal dunes have recently been discovered by the titan radar mapper on the surface of titan these are found mainly within 30 of the equator in optically near infrared and radar dark regions indicating a strong proportion of organics and cover well over 5 of titan s surface their longitudinal duneform interactions with topography and correlation with other aeolian forms indicate a single dominant wind direction aligned with the dune axis plus lesser off axis or seasonally alternating winds global compilations of dune orientations reveal the mean wind direction is dominantly eastwards with regional and local variations where winds are diverted around topographically high features such as mountain blocks or broad landforms global winds may carry sediments from high latitude regions to equatorial regions where relatively drier conditions prevail and the particles are reworked into dunes perhaps on timescales of thousands to tens of thousands of years on titan adequate sediment supply sufficient wind and the absence of sediment carriage and trapping by fluids are the dominant factors in the presence of dunes

syenitic group intrusions of the archean kurnalpi terrane yilgarn craton hosts to ancient alkali porphyry gold deposits abstract archean alkali rich syenitic group intrusions in the eastern goldfields superterrane yilgarn craton are chemically similar to intrusions associated with phanerozoic alkali porphyry systems high temperature potassic and ferruginous alteration associated with the yilgarn intrusions are also similar to those in phanerozoic counterparts but these are generally not well mineralized disseminated and fracture controlled gold mineralization associated with syenitic group intrusions is commonly hosted by mesothermal albite carbonate pyrite assemblages the origin of which is ambiguous this communication aims to stimulate discussion on the origin of gold in and around syenitic group intrusions and the apparent absence of significant gold or copper mineralization in associated high temperature alteration gold associated with syenitic group intrusions in the yilgarn craton has many similar characteristics to disseminated gold deposits associated with syenitic intrusions in the abitibi greenstone belt canada and may be present in other archean greenstone belts

aspects of sand behaviour by modified constant shear drained tests constant shear drained tests csd are probably the most suitable to simulate the strength and deformation behaviour of soils in slopes under water infiltration conditions or lateral stress relief this is significant because soil behaviour following a csd stress path could differ from that of traditional compression triaxial tests in this paper csd tests on sand following an alternative procedure are presented and discussed the modified csd tests were conducted by increasing the pore water pressure at a constant rate from one end of the specimen with water free to drain from the opposite end among the results from specimens consolidated at variable initial void ratios and principal stress ratios it was revealed that specimens showed a tendency to dilate even for loose sands failure was reached at low axial strains and a pre failure type of instability could be identified the modified procedure has the potential to provide new insights into the failure mechanisms of slopes under a water infiltration condition

geodynamics of the eastern yilgarn craton abstract over the last decade there have been significant advances in our understanding of the stratigraphy magmatism deformation metamorphism and timing of mineralisation in the eastern yilgarn craton eyc of western australia the integration of these disciplines has enabled a holistic review of the tectonic history of the eyc which favours a paraautochthonous tectonic model a significant advance has been the recognition of a 2810 ma rifting event off the eastern margin of the youanmi terrane which set up the north northwest trending architecture of the eyc rifting was followed by a 100 myr long phase of tectonic activity initiated by the establishment of a convergent margin at 2715 ma characterised by a west dipping subduction zone to the east of the eyc subduction was associated with the deposition of 2715 2670 ma volcanic stratigraphy and the emplacement of voluminous tonalite trondhjemite granodiorite magmatism which resulted in magmatic thickening of the crust volcanism was terminated by a 5 myr pulse of east northeast contraction followed by mid orogenic extension possibly linked to lithospheric and lower crustal delamination the lack of ultra high pressure metamorphism and the presence of high geothermal gradients preclude this contractional event from recording continent continent collision mid orogenic extension at 2665 ma resulted in the introduction of metasomatised mantle melts mafic granites and syenites deposition of siliciclastic basins which record metamorphic anticlockwise ptt paths and the start of significant economic gold mineralisation in the eyc high stretching factors and or delamination associated with this extension event resulted in significant heat input into the base of the crust which eventually led to the emplacement of low ca crustal melt granites and cratonisation of the eyc major gold mineralisation postdates mid orogenic extension and was associated with renewed compression transpression 2650 ma and the development of steep predominantly north northwest striking sinistral and later north to north northeast striking dextral strike slip faults during low ca granite emplacement

stress damage flow coupling model and its application to pressure relief coal bed methane in deep coal seam abstract long distance pressure relief gas drainage technology has recently been applied in mining areas with multiple coal seams of low permeability in china this study briefly described a coupled stress damage flow model which combined the evolution of stress damage and gas permeability with the deformation of coal and rock the coupled model was then used to investigate the deformation and fracture characteristics of overburden strata the evolution of gas permeability and gas flow in target coal seams the effectiveness of long distance pressure relief gas drainage was evaluated on the basis of the calculated results from a dynamic modelling of extraction of protective coal seam at great depths the numerical results revealed that the stress was remarkably relieved in the target coal seam above 67 m away from the coal seam being mined moreover the range of stress relief extended above 70 m and the gas permeability increased by more than 2000 times the modelled results reasonably well agreed with the field results observed in the panyi coal mine it was concluded that the long distance pressure relief gas drainage technology could effectively improve the safety and productivity in underground coal mines especially in mining areas with multiple coal seams of low permeability

global pattern of titan s dunes radar survey from the cassini prime mission 1 we present a map of the orientation and extent of titan s sand dunes derived from the complete radar imaging dataset from the cassini prime mission the 16 000 dune segments we have mapped cover 8 of the titan s surface suggesting a total coverage of 20 are confined within 30 of the equator and show local and regional deviations of dune orientation of up to about 40 from due eastwards there is no obvious global longitudinal pattern although some divergence with latitude is apparent the most striking pattern is one of collimation by and divergence around bright and or high terrain obstacles 100 300 m high obstruct dunes when the local slope is 1 50 or steeper while slopes 1 200 or shallower cause dunes to thin out as they climb or to deviate around the obstacles

application of the geomechanical facies approach and comparison of exploration and evaluation methods used at soultz sous forets france and spa urach germany geothermal sites earth reservoirs are increasingly exploited today with the extraction of resources such as heat and hydrocarbons and the large scale emplacement of waste such as co2 sequestration the characterization site investigation predictive modeling and long term monitoring are dependent on the processes being investigated and modeled in most cases complex coupled processes have to be addressed in a geologically complex rock mass system in this paper we present a conceptual holistic framework known as geomechanical facies linking all the scales of investigation characterization and reservoir development methods we demonstrate this concept on the work undertaken during the design and development of the enhanced geothermal systems egs systems at the forefront of european hot dry rock hdr technology soultz sous forets france and spa urach germany soultz sous forets is situated within granitic rocks and an active tectonic graben system in the central part of the rhine graben it presents conditions of lithology temperature stress hydraulics and geochemistry that are very different from those at spa urach located in a very dense gneiss formation in the south german crystalline complex spa urach exhibits more elastic behavior and is set tectonically within an almost inactive strike slip stress field described in more detail in sects drill core analysis and hydraulic stimulation at spa urach this paper compares the exploration and field development methods used at these two sites against the back drop of the geomechanical facies concept issues addressed include the key parameters for flow and heat transport properties coupled hydro mechanical process identification the success of the hdr reservoir as a heat exchanger and exploration techniques applicable to the different facies identification of the key geomechanical facies gives an indication as to which technologies will prove more efficient in the application of hdr technology the results of this study will hopefully help in developing heat recovery schemes for the long term economical operation of future hdr plants and egs as well as assist in the understanding of engineered geosystems

comparison of metasomatic reactions between a common co 2 rich vein fluid and diverse wall rocks intensive variables mass transfers and au mineralization at alleghany california the gold deposits at alleghany california are typical of many epigenetic gold bearing hydrothermal vein systems in metamorphic terranes worldwide detailed analyses of alteration halos in serpentinite mafic amphibolite and granite wall rocks at alleghany indicate that widely contrasting deposit types ranging from fuchsite carbonate schists to pyrite albitites resulted when different wall rocks interacted with the same externally derived co 2 rich hydrothermal vein fluid patterns of element redistribution within halos and among lithologic units suggest a complex process involving fluid flow along vein fractures and diffusion or infiltration normal to the veins wall rocks locally controlled both the directions and magnitudes of chemical fluxes across vein walls vein fluids at constant temperature and pressure with relatively constant ratios of mobile species na super k super h super and co 2 h 2 s h 2 caused contrasting divergent reactions in proximal alteration zones because the wall rocks controlled the ratios of relatively immobile species al cr fe mg and fe mg and the component activities of hydrothermal mineral solid solutions thus pyrite and albite were stable with respect to the relatively pure siderite and k mica that occur sparingly in proximal granite zones but they were not stable with respect to the relatively impure siderite and k mica that characterize proximal serpentinite zones partly as a result of divergent reactions altered rocks exhibit contrasting mobile element concentration gradients e g ca ba sr rb na k c s and imply local sources and sinks and possibly short residence times for some of these components along discordant fluid flow paths calculated reaction coefficients for h super h 2 and h 2 s indicate that different wall rocks at different stages of alteration may have inhibited or promoted gold precipitation the distribution of gold and its calculated solubility are consistent with its having been precipitated from au hs 2 super complexes in response to pyritization of granite fluid desulfidation and reduction and possibly in part in response to dolomitization and sericitization of serpentinite fluid acidification strata bound disseminated orebodies may be expected in a variety of other host rocks with higher than average fe mg ratios where pyrite was stable with respect to intermediate magnesite siderite as in the granite it is proposed that the co 2 rich vein fluids approached partial equilibrium with alteration assemblages in the average or dominant rocks along their flow paths simpler but radically different proximal assemblages were then produced where the fluids encountered chemically extreme rock types fluid rock interaction equilibria can account for much of the diversity in the mineralogy and chemistry of gold deposits in heterogeneous metamorphic terranes while maintaining a simple genetic classification based on the distinctive chemistry of the hydrothermal fluids comparative studies of multicomponent phase equilibria and mass exchanges can provide both rationalizations and predictions of local wall rock effects on geochemical anomalies and the locations of ore deposits in lithologically heterogeneous terranes simultaneous consideration of contrasting high variance phase deficient assemblages along discordant veins is suggested as a general method for quantifying fluid intensive variables in metasomatic systems

titan s surface revealed by hst imaging we present for the first time relative albedo maps of titan s surface the maps were made from images taken by the hubble space telescope s planetary camera 295 km per pixel through atmospheric windows at 940 and 1080 nm coverage at all longitudes and between 45 s and 60 n was obtained with 14 orbits from 4 18 october 1994 each image is characterized by haze with both limb effects brightening and a large north south contrast subtracting an averaged image from each frame removes haze effects and reveals surface features of 10 maximum contrast many features are clearly visible in multiple images and in both filters but the surface map is dominated by a large bright roughly rectangular feature centered at 110 w 10 s and elongated in an east west direction 4000 2500 km2 this feature and others indicate the diversity of titan s surface we consider the origin of the bright feature in an otherwise dark landscape and suggest that highland washing by methane rainfall is a likely mechanism

tectonics and distribution of gold deposits in china an overview gold exploration in china has expanded rapidly during the last two decades since a modern approach to economic development has become a national priority china currently produces 180 tonnes t of gold annually which is still significantly less than south africa usa and australia however china is now recognized as possessing significant gold resources in a wide range of mineral deposit types present estimates of gold resources in china exceed 4 500 t which comprise 60 in gold only deposits more than 25 in base metal rich skarn porphyry and vein deposits and more than 10 in placer accumulations the major gold provinces in china formed during the main episodes of phanerozoic tectonism such tectonism involved interaction of china s three major precambrian cratons north china tarim and yangtze or south china when combined with cathaysia block with the angara or siberian kazakhstan kyrgyzstan and indian cratons resulting collisions included deformation of accreted oceanic sequences between the cratonic blocks the most important ore forming orogenies were 1 the late paleozoic variscan 405 270 ma which led to amalgamation of the angara north china and yangtze cratons 2 the indosinian 270 208 ma which led to the collision of north china and south china cratons 3 the yanshanian 208 90 ma which was largely influenced by the subduction of the izanagi pacific plates beneath eastern china and 4 the himalayan 90 ma indentation of the indian continent into eurasia no important precambrian gold systems are recognized in china mainly because of reworking of exposed precambrian rocks by these younger orogenies but there are a few caledonian 600 405 ma gold bearing systems in northern xinjiang most of china s orogenic epithermal and carlin like gold deposits are in the reworked margins of major cratonic blocks and in metasedimentary rock dominated fold belts adjacent to these margins accordingly the major gold provinces are present along the northern southeastern and southern margins of the north china craton along the southwestern and northwestern margins of the yangtze craton in the tianshan and altayshan orogenic belts in northern xinjiang and throughout the southeastern china fold belt gold placer deposits derived from these primary deposits are concentrated in the northernmost part of northeastern china and along the northwestern margin of the yangtze craton the major provinces with significant gold in porphyry related copper systems and base metal skarns are present in the yangtze river area along the northeastern and southeastern margin of the yangtze craton in the fold belt in southwestern china and scattered through northern china three quarters of the chinese gold only deposits occur within the north china craton margins half are located in the uplifted precambrian metamorphic rocks and most of the remainder are hosted in the phanerozoic granitoids that intruded the reworked precambrian terranes the abundance of granite hosted gold contrasts the north china craton with other precambrian cratons such as those in western australia central canada and zimbabwe where gold is mainly hosted in the archean greenstone belts this difference may be explained by the multiple episodes of phanerozoic tectonism along the north china craton margins resulting from the collision of the angara north china and south china cratons and from subduction of the izanagi pacific oceanic plates underneath the eastern china continent

the sand seas of titan cassini radar observations of longitudinal dunes the most recent cassini radar images of titan show widespread regions up to 1500 kilometers by 200 kilometers of near parallel radar dark linear features that appear to be seas of longitudinal dunes similar to those seen in the namib desert on earth the ku band 2 17 centimeter wavelength images show 100 meter ridges consistent with duneforms and reveal flow interactions with underlying hills the distribution and orientation of the dunes support a model of fluctuating surface winds of 0 5 meter per second resulting from the combination of an eastward flow with a variable tidal wind the existence of dunes also requires geological processes that create sand sized 100 to 300 micrometer particulates and a lack of persistent equatorial surface liquids to act as sand traps

influence of continuous rainfall on surrounding rock initial support system of shallow decomposed rock tunnel a case study is presented to identify the influence of continuous rainfall on surrounding rock initial support system of shallow decomposed rock tunnel from march 21 to april 29 2006 rainfall with intensities ranging from 25 mm day fell several hours every day resulting in the collapse of the tunnel crown after the initial support of the surrounding rock in a part of shallow tunneling bench sections of xiang an subsea tunnel located in xiamen fujian china the applied calculation method of 3d elastic plastic numerical back analysis based upon flac3d is presented through site investigation test and in situ monitoring the surrounding rock physical mechanics parameters and support parameters were obtained by the calculation of elastic plastic back analysis method presented here furthermore the influence of continuous rainfall on the stability of shallow decomposed rock tunnel was investigated using the proposed method the results show that 1 rainwater infiltration makes the surrounding rock of the shallow decomposed rock tunnel continuously softened due to the continuous rain resulting in decreasing surrounding rock stiffness and coefficient of confinement pressure 2 the negative influence of groundwater must be considered on the initial setting and initial strength of shotcreting of shallow decomposed rock tunnel under the action of continuous rainfall to ensure the stabilization of surrounding rock initial support system and 3 tunnel stability analysis by the back analysis method proposed in this study is reasonable and reliable which could be used as a reference for the estimation of stability of the same type of tunnels and their design

vertical and lateral variation of mineralogy and chemistry in the early jurassic mt milligan alkalic porphyry au cu deposit british columbia canada the moderately tilted and faulted early jurassic mt milligan au cu deposit provides a cross section view of the hydrothermal alteration sulfide mineralogy and geochemical zonation of a silica saturated alkalic porphyry system over a vertical distance approaching 700 m magnetite bearing potassic alteration and associated au cu form a core to the system in the central monzonitic stock and adjacent basaltic trachyandesite host rock lateral to the high temperature core are sodic calcic and inner and outer propylitic alteration assemblages chalcopyrite dominates the high temperature potassic core whereas pyrite is the predominant sulfide within and outboard from the sodic calcic assemblage a funnel shaped remnant of carbonate rich phyllic alteration of the host supracrustal rocks in the fault bounded 66 zone represents the upper auriferous alteration in the alkalic porphyry au cu system alteration mineral assemblage s isotope ranging from 34s 5 relative to canon diablo troilite in the core to 34s 0 5 in the periphery and limited fluid inclusion data suggest mineralization at the au cu alkalic porphyry system was derived from an oxidized co2 bearing magmatic fluid that rose upward along the margins and through the magnetite breccia stock laterally from the au cu mineralized potassic core magmatic fluid evolved through water rock interaction mixing with an external fluid as shown by a shift in calculated 87sr 86sr for alteration minerals to values higher than magmatic values declining temperature or some combination of all variations in trace element concentrations of epidote v mn sb zr as and bi and pyrite mn as zr pb and bi across the deposit show a local high degree of variability but general increases or decreases in overall trends in their median values are inferred to reflect the hydrothermal evolution of the system pistachite ratios of epidote show an outward decrease in ferric iron as recorded in the pistachite ratio changing from ps36 to ps25 suggesting less oxidizing conditions on the system periphery additionally light rare earth elements in epidote fractionate toward the core of the deposit and the height of positive eu anomalies also appears to have a similar spatial trend in pyrite there is a general increase in trace element concentration toward the epidote pyrite rich outer propylitic assemblage forming the system periphery alteration mineralogy and trace element signatures indicate the southeastern portion of the deposit the 66 zone is a down dropped segment from higher in the paleohydrothermal system s isotope signatures of sulfides within and surrounding the stratiform upper trachyte unit in the 66 zone indicate structural channeling of oxidizing fluids that likely were the distal and cooler expression of more oxidizing magmatic derived hydrothermal fluids responsible for potassic alteration and au cu in the subjacent magnetite breccia zone the main orebody

fluvial network analysis on titan evidence for subsurface structures and west to east wind flow southwestern xanadu 1 data of titan s surface from the cassini huygens mission show inferred fluvial networks interpreted as products of liquid alkane flow using synthetic aperture radar sar data we delineated drainage networks measured network parameters and used these measurements in a simplified algorithm for classifying terrestrial drainage patterns the results show a variety of patterns indicating that a variety of factors control fluvial drainage on titan drainage network patterns in southwestern xanadu are classified as rectangular suggesting control by a subsurface tectonic structural fabric link orientations also suggest that thissubsurfacetectonicfabricisorientedpredominantlyeastwest spatial variations in drainage networks are consistent with a west to east precipitation pattern supporting inferences from aeolian dune morphology these results illustrate how fluvial landform analysis can yield new information on both atmospheric and subsurface processes citation burr d m r e jacobsen d l roth c b phillips k l mitchell and d viola 2009 fluvial network analysis on titan evidence for subsurface structures and west to east wind flow southwestern xanadu geophys res lett 36 l22203

high sr y arc magmas and porphyry cu mo au deposits just add water porphyry cu mo au deposits are commonly associated with intermediate composition arc related igneous rocks with high sr y and la yb ratios and such rocks are equated by some researchers with melts derived from subducted oceanic crust undergoing eclogite facies metamorphism adakites however similar geochemical characteristics are readily developed in normal asthenospheric mantle wedge derived magmas by fractionation of amphibole and or garnet and or by interaction with crustal materials during ascent through the upper plate lithosphere while there is widespread evidence for such fractionation and contamination processes in porphyry magmas there is little direct evidence for an origin by slab melting the enhanced fertility of arc magmas relates primarily to their high water content which is required for the formation of magmatic hydrothermal systems upon shallow crustal emplacement magmatic water contents 4 wt percent h 2 o cause abundant amphibole garnet fractionation but suppression of plagioclase crystallization at deep crustal levels resulting in increasing sr y and la yb ratios with differentiation commonly into adakitic ranges but not reflecting slab melting additional factors that affect arc magma fertility are relatively high oxidation states and sulfur content but these are secondary to the requirement for sufficient water thus arc magmatic suites with high sr y ratios and evidence for the presence of hydrous phenocryst phases hornblende and or biotite are indeed prospective for porphyry cu mo au deposits but only because these parameters indicate high magmatic water content

microwave dielectric constant of liquid hydrocarbons application to the depth estimation of titan s lakes 1 cassini radar reveals the surface of titan since flyby ta acquired on october 2004 the radar instrument discovered volcanic structures craters dunes channels lakes and seas in particular flyby t16 realized in july 2006 imaged tens of radar dark features close to titan s north pole they are interpreted as lakes filled with liquid hydrocarbons mainly methane a key material in the geologic and climatic history of titan in order to perform quantitative analysis and modeling of the radar response of titan s lakes the dielectric constant of liquid hydrocarbons is a crucial parameter in particular to estimate the radar wave attenuation we present here first measurements of the dielectric constant of lng liquefied natural gas mainly composed of methane at ku band 10 13 ghz we obtained a value 1 75 0 002j this value is used to model the radar backscattering of lakes observed during t16 flyby using a two layer scattering model we derive a relationship that is used to estimate a minimum depth for titan s lakes the proposed relationship is also coherent with the observation that the larger and then the deeper lakes are also the darker in radar images

dual polarization radar observations of mars tharsis and environs abstract observations of the tharsis region of mars with the 12 6 cm radar at arecibo observatory have yielded radar echoes which are highly depolarizes and which are in terms of total echo power dominated by diffuse rather than quasi specular backscattering the observations were made on february 7 8 and 9 1980 and the subradar track extended from 77 to 126 w longitude at 22 n latitude dual polarized reception was employed i e the echo was received in the same sense of circular polarization as transmitted depolarized sense as well as in the opposite polarized sense the disk integrated ratio of depolarized power to polarized power averages 0 37 and the ratio of diffuse power to quasi specular power averages 3 2 the depolarized spectra are dominated by a broad enhancement identified primarily with echoes from the tharsis ridge implying that extensive areas of tharsis are rough on decimeter scales the major tharsis shield volcanoes are candidates for sources of strong depolarization although they alone cannot account for the entire depolarization enhancement

evolution and effect of the stress concentration and rock failure in the deep multi seam coal mining supports crushing accident occasionally occurs in the protected seam exploitation of deep multi seam coal mining structure and results in adverse effect to the production to prevent its recurrence in a newly developed working field a 3d numerical extraction model was built based on the geologic and mining conditions of jining coal mine to evolve the changes state and characteristics of the reconstructed vertical and lateral stress in rock interlayer after protective seam exploitation stress release and increase zones of this mining structure were separated mining induced localized stress concentration and the interlayer rock failure behavior were explored the action of concentrated stress on the hydraulic supports in protected seam was discussed upon the major stress redistribution using the infinitesimal strain method a mechanical model was created to further explore from the vertical and lateral directions the cause and mechanism of localized stress concentration and rock failure behavior in rock interlayer the field investigation was finally performed to verify the numerical and mechanical results and the essential control measures were proposed to prevent this accident key findings of this study bring some new insights into the deep multi seam coal extraction and help to promote a more reliable underground mining

application of 3d laser scanner optical transducers and digital image processing techniques in physical modelling of mining related strata movement a physical testing protocol for modelling mining related problems has been presented a new method for monitoring fracture propagation pattern has been introduced laser based and optical devices have been used for physical modelling of subsidence multiple seam subsidence has been measured by photogrammetry dic analysis optoncdt and 3d tls

introduction to the special issue devoted to alkalic porphyry cu au and epithermal au deposits this special issue is devoted to alkalic porphyry cu au and epithermal au deposits and focuses on two regions british columbia canada fig 1 and the southwest pacific region australia and papua new guinea fig 2 the special issue commences with a review of triassic to jurassic metallogeny of british columbia logan and mihalynuk 2014 then documents ore zones from several alkalic deposits central zone galore creek micko et al 2014 southwest zone galore creek byrne and tosdal 2014 northeast zone mt polley pass et al 2014 lower main zone lorraine bath et al 2014 mt milligan jago et al 2014 and provides a comprehensive overview of mineralization in the lorraine district devine et al 2014 four contributions document alkalic porphyry and epithermal deposits in new south wales northparkes harris and holcombe 2014 endeavour 41 zukowski et al 2014 endeavour 42 henry et al 2014 cadia harris et al 2014 the final contribution uses the results of mapping and core logging in order to resolve the physical volcanology and hydrothermal evolution of the giant ladolam alkalic epithermal gold deposit papua new guinea blackwell et al 2014 eight of these papers are the outcome of a collaborative project between the mineral deposit research unit mdru at the university of british columbia the australian research council s centre for excellence in ore deposits codes at the university of tasmania and industry partners the remaining are based on work by the british columbia geological survey logan and mihalynuk 2014 teck resources ltd devine et al 2014 a research collaboration between codes and newcrest mining ltd harris et al 2014 and the university of queensland harris and holcombe 2014 fig 1 terrane map and location of selected alkalic porphyry cu au deposits of british columbia deposits that are the subject of

titan s diverse landscapes as evidenced by cassini radar s third and fourth looks at titan abstract cassini s third and fourth radar flybys t7 and t8 covered diverse terrains in the high southern and equatorial latitudes respectively the t7 synthetic aperture radar sar swath is somewhat more straightforward to understand in terms of a progressive poleward descent from a high dissected and partly hilly terrain down to a low flat plain with embayments and deposits suggestive of the past or even current presence of hydrocarbon liquids the t8 swath is dominated by dunes likely made of organic solids but also contain somewhat enigmatic probably tectonic features that may be partly buried or degraded by erosion or relaxation in a thin crust the dark areas in t7 show no dune morphology unlike the dark areas in t8 but are radiometrically warm like the dunes the huygens landing site lies on the edge of the t8 swath correlation of the radar and huygens disr images allows accurate determination of its coordinates and indicates that to the north of the landing site sit two large longitudinal dunes indeed had the huygens probe trajectory been just 10 km north of where it actually was images of large sand dunes would have been returned in place of the fluvially dissected terrain actually seen illustrating the strong diversity of titan s landscapes even at local scales

the tide in the seas of titan the surface temperature of titan1 is about 95 k between the melting point 90 6 k and the boiling point 118 k of methane at the total surface pressure of 1 6 bar voyager 1 ir observations1 2 suggest a methane abundance in the lower atmosphere 0 19 of saturation comparison with the mean h2o abundance in the earth s atmosphere suggests1 a ch4 saturation level 0 5 thus the volume mixing ratio of methane is probably about 6 and methane begins to condense out some 40 km above the surface it is therefore a natural speculation that methane exists in the liquid state on the surface of titan the atmospheric ch4 corresponds to a liquid layer 10 m deep but it is unlikely that the buffer for atmospheric methane would have a capacity equal only to that of the atmosphere itself on earth the quantity of water in the oceans is on average several times 104 the quantity of water vapour in the atmosphere thus if titan has oceans of liquid ch4 they are probably 100 m deep we argue here that if this ocean exists the present high eccentricity of titan requires its depth to be 400 m and that such an ocean can be detected by radar techniques

cassini radar images at hotei arcus and western xanadu titan evidence for geologically recent cryovolcanic activity 1 images obtained by the cassini titan radar mapper radar reveal lobate flowlike features in the hotei arcus region that embay and cover surrounding terrains and channels we conclude that they are cryovolcanic lava flows younger than surrounding terrain although we cannot reject the sedimentary alternative their appearance is grossly similar to another region in western xanadu and unlike most of the other volcanic regions on titan both regions correspond to those identified by cassini s visual and infrared mapping spectrometer vims as having variable infrared brightness strengthening the case that these are recent cryovolcanoes citation wall s d et al 2009 cassini radar images at hotei arcus and western xanadu titan evidence for geologically recent cryovolcanic activity geophys res lett 36 l04203 doi 10 1029 2008gl036415

magmatic oxidation in the syenitic murdock creek intrusion kirkland lake ontario evidence from the ferromagnesian silicates the syenitic murdock creek intrusion of late archean age lies within one of the major lode gold camps of the world at kirkland lake ontario there is a strong spatial association between syenitic intrusions gold mineralization and carbonatization hydrothermal fluids that carried the gold had an unusually high oxygen fugacity f o 2 notwithstanding a wide range in rock compositions within the intrusion from clino pyroxenite to alkali feldspar syenite clinopyroxene and biotite have consistently low fe fe mg and high fe 3 fe 2 fe 3 ratios these compositional features indicate a deficiency of fe 2 in the magma during crystallization together with the presence of abundant early formed magnetite and titanite this is interpreted to result from an intrinsically high magmatic f o 2 that remained constant during pluton evolution f o 2 approx 10 12 bars mineral compositions proportions of crystallizing mineral phases and textural features i

granitoid associated orogenic intrusion related and porphyry style metal deposits in the archean yilgarn craton western australia abstract the yilgarn craton hosts three types of archean granitoid associated metallogenic systems orogenic gold intrusion related and porphyry systems these systems may occur in the same terrane and share many broad characteristics including spatial coincidence with granitoids gangue silicate mineralogy metal associations and local structural controls features of archean orogenic gold systems spatially associated with granitoids include i a broad range of granitoid host compositions ii gold mineralization is mostly late with respect to yilgarn wide granitoid emplacement peak metamorphism and deformation iii orebodies are structurally controlled and iv gold deposition occurs over a large range of temperatures pressures and crustal depths 2 to 15 km from a co 2 rich low to moderate salinity reduced ore fluid that was derived from a metamorphic and or distal magmatic fluid source these systems do not display deposit scale vertical or lateral zonation of metals away from granitoid contacts host granitoid age composition or oxidation state are not important in controlling gold mineralization processes whereas structural setting and fluid flux are paramount archean intrusion related au mo w and mo au systems in the yilgarn craton are commonly small 2 bearing moderate to high salinity fluid during ore deposition archean porphyry cu mo au cu mo and cu au systems are spatially and temporally associated with volumetrically small pervasively altered felsic plutons and dikes surrounded by altered and mineralized supracrustal countryrock lateral zonation of metals away from porphyry centers commonly includes a decrease in cu au and ag au ratios with distance from the source pluton microthermometry studies on fluid inclusions in gold bearing veins suggest that early ore fluids were high temperature and high salinity and that mineralization occurred at 2 o 3 feo are demonstrated in phanerozoic terranes but are presently ill defined in the yilgarn craton crustal depth estimation is important in defining areas likely to have preserve shallow forming archean porphyry systems

geology mineralogy and geochemistry of magnetite associated au mineralization of the ultramafic basalt greenstone hosted crusader complex agnew gold camp eastern yilgarn craton western australia a late archean intrusion related au deposit abstract the crusader complex part of the agnew gold camp of the lawlers anticline of the yilgarn craton western australia is located close to or along the contact between the lawlers basalt and agnew ultramafics units au mineralization within the four orebodies that form the crusader complex is dominated by very pure au containing less than 1 wt ag with au variably associated with scheelite bi tellurides and minor chalcopyrite within a magnetite and titanite gangue assemblage hydrothermal alteration associated with this style of mineralization is characterized by increasing concentrations of mo be li sn and fe and depletions in na cu ba pb mn zn si and k relative to protolith concentrations these enrichments are more typical in orebodies associated with felsic intrusive related mineralizing systems rather than the more well known orogenic au deposits found elsewhere within the lawlers anticline e g at waroonga and within the greater yilgarn craton we propose that flexures of the contact between the lawlers basalt and agnew ultramafic units acted as conduits for au bearing felsic intrusive derived fluids and generated structural traps that enhanced fluid flow the mineralizing fluids that formed the crusader deposits were derived from the lawlers granitoid pluton that intruded into the study area enhanced fluid flow promoted interaction between hydrothermal fluids and the reactive mafic ultramafic rock sequence augmenting the amount of au that was precipitated during formation of the orebodies at crusader the magnetite dominated quartz and sulfide poor intrusion related mineralization at crusader contrasts sharply with other late archean intrusion related deposits of the yilgarn craton that are usually sulfide and or quartz rich this may in turn suggest that the crusader deposit represents a new class of under explored intrusion derived deposits possibly opening new mineral exploration opportunities for the agnew region and potentially the wider eastern goldfields superterrane enrichments in mo and sn and significant depletions in cu suggest that other parts of the lawlers batholith may also be prospective for base metal mineralization integration of stratigraphic interpretation with the identification of key structural fluid pathways and the presence of felsic intrusive bodies as presented in this study enables the delineation of the key elements that underlie mineralization at the crusader complex we propose that these key elements provide vital information for future gold exploration models that can be used within other archean terranes and within the eastern yilgarn craton in particular