long runout rockslide on glacier at tsar mountain canadian rocky mountains potential triggers seismic and glaciological implications a rhomboidal shaped rockslide with a length of 2 2 km and an area of 1 35 km2 covers 30 of a small clemenceau icefield group cirque glacier by means of remote sensing airborne photography climate and seismic data analysis the extent timing possible trigger mechanisms and rockslide effects on the glacier are discussed an ml 2 0 seismic event on 14 september 2000 represents the rockslide and has a spindle shaped waveform and high energy in the low frequencies based on a strong signal duration of 56 108 seconds the rockslide had an average runout velocity of 22 45 m s 1 stress fatigue and a combination of rain and snow followed by rapid melt and night time freezing could have co triggered the slide additional seismic events with epicentres 40 km from the cirque were recorded 26 times since 1985 and range between ml 0 9 3 3 but none were caused by or triggered large mass movement with a rock source volume of 1 6 106 m3 and a deposited volume of 2 4 106 m3 the sum of bulking and entrainment is between 25 and 150 five melt seasons post event levees 20 30 m wide tower 30 m over the surrounding glacier rockslide characteristics and its fahrboschung of 15 height length h l 0 28 indicate that this rockslide is quite typical for long runout rockslides on glaciers however the basal friction coefficient was higher than found on other glaciers and could relate to the presence of medial moraines transverse to the flowline and to pre slide debris cover the difference between the coefficient of friction in the main flowline 0 11 0 14 and that in a lobe confined between two medial moraines 0 065 suggests that confinement increases mobility by 70 115 apart from reduced ablation under the rock debris effects of the rockslide on the glacier were minimal copyright 2010 john wiley sons ltd

change in longitudinal profile on three north cascades glaciers during the last 100 years centreline surface elevation longitudinal profiles have been completed for three different points in time from historic photographs 1900 us geological survey maps 1964 and 1985 and field measurements annually between 1984 and the present for three north cascade glaciers comparison of thinning and terminus behaviour over this time period indicates substantial overall volume loss during this century for each glacier mean thickness changes along the longitudinal profile of easton glacier are losses of 46 m 0 68 m year 1 of ice thickness between 1916 and 1984 and 13 m 0 72 m year 1 between 1984 and 2002 its terminus has retreated a net distance of 2123 m lower curtis glacier lost an average of 45 m 0 60 m year 1 thickness from 1908 to 1984 and 6 m 0 33 m year 1 from 1984 to 2002 with a net terminus retreat of 522 m on columbia glacier ice thickness loss was 57 m 0 78 m year 1 from 1911 to 1984 and 8 m 0 44 m year 1 from 1984 to 2002 the net terminus retreat for columbia was 640 m thickness changes are approximately equal in the accumulation zone of the columbia and lower curtis glacier during the 20th century and from 1984 to 2002 this suggests that there is no position to which the glacier can retreat and achieve equilibrium the changes on each glacier which today average less than 75 m in thickness represent the loss of 35 50 in their volume since the turn of the century and 10 15 of this volume since 1984 their ongoing thinning indicates that these three glaciers will continue to retreat in the foreseeable future the columbia glacier likely disappearing long term monitoring of these glaciers should continue in order to assess the impact on downstream flow which is utilized for hydropower on easton and lower curtis glaciers and a salmon hatchery on columbia glacier

influence of temperature on seismic velocities and complex conductivity of heavy oil bearing sands abstractthe joint inversion of seismic and electromagnetic data can be of great use to monitor the steam assisted production of heavy oils in field conditions seismic velocity and complex conductivity laboratory measurements were performed on three heavy oil bearing sands at confining and pore pressures similar to field conditions one of the samples 8h was initially oil wet and the two other samples 5p 3a and p 1a were initially water wet low frequency stress strain measurements and complex conductivity measurements were performed during two heating cycles at constant temperature 10 c steps in the range 20 c 70 c the temperature was first increased from 20 c 70 c simulating initial stage in a thermal recovery process during this temperature increase sample 8h changed to water wet with a clear irreversible signature on the seismic and electrical data then the temperature was decreased and cycled a second time in the temperature range 20 c 70 c the seismic and complex conductivity responses w

effect of secondary minerals on electrokinetic phenomena during water rock interaction 1 the main geophysical application of spontaneous potentials sp anomalies i e electrical signal generated by hydroelectric coupling is the mapping of hydrothermal zones laboratory studies of hydroelectric coupling as a function of temperature are scarce because of experimental difficulties up today experiments carried out by ishido and mizutani 1981 with quartz al k no3 system for temperatures ranging from 20 c to 80 c are not well understood in this work we show that ishido and mizutani 1981 s solutions are oversaturated with aluminium and that the precipitation of al oh 3s is expected triple layer model tlm calculations for a gibbsite kno3 system can account for ishido and mizutani 1981 s measurements these results highlight that 1 the precipitation of a secondary mineral can hide the electrical properties of the primary rock 2 the geochemical fluid surveys should be taken into account to grasp the interfacial processes precipitation dissolution and to interpret the sp measurements in the field

importance of structural history in the summit area of stromboli during the 2002 2003 eruptive crisis inferred from temperature soil co2 self potential and electrical resistivity tomography the 2002 2003 eruptive crisis of stromboli volcano in the aeolian islands raised the question of how to assess the stability of the flanks of this volcanic edifice during such a crisis to provide a response to this question we analyzed a detailed fluid flow mapping plus the reiteration of a profile located in the vicinity of the active vents using the self potential method temperature data soil gas co2 measurements and electric resistivity tomography coupling the interpretation of these methods that are sensitive to the flow of gas and water in the ground indicates the position of areas of mechanical weakness in addition they can be used to monitor the change in the discharge of fluids associated with these features before and during the 2002 2003 eruptive crisis our results emphasize the importance of old structural boundaries such as the large fossa crater in the development of the new set of fractures observed during the 2002 2003 eruptive crisis between october 2002 and january 2003 the use of co2 soil gas technique evidenced an increase in the discharge of co2 outside the large fossa crater boundaries along the failure boundary of the southern sciara del fuoco area self potential and temperature measurements made before the 2002 2003 eruptive crisis reveal significant changes along the main structural boundaries of the fossa area the development of these anomalies is interpreted as an increase of the permeability of the structure from may 2000 to may 2002 between january 2003 and march 2003 the reiteration of self potential temperature and co2 measurements shows an increase of fluid discharge along weakness planes located inside the large fossa crater boundary they evidence no change outside this structural boundary the importance of the large fossa crater boundary in controlling the deformation and fluid flow from january to march 2003 has been attested by the development of the fractures inside the large fossa crater boundary and also with a network of electrooptical distance measurement stations located inside and outside this ancient crater this multidisciplinary approach to fluid flow assessment before and during an eruptive crisis is complementary to geodetic measurements of the deformation of the edifice it demonstrates for the first time the powerful potential of combining electrical resistivity tomography self potential temperature and soil co2 measurements in assessing the position of the planes of mechanical weakness in a volcanic edifice

pore scale modeling of electrical and fluid transport in berea sandstone the purpose of this paper is to test how well numerical calculations can predict transport properties of porous permeable rock given its 3d digital microtomography ct image for this study a berea 500 sandstone sample is used whose ct images have been obtained with resolution of 2 8 m porosity electrical conductivity permeability and surface area are calculated from the ct image and compared with laboratory measured values for transport properties electrical conductivity permeability a finite difference scheme is adopted the calculated and measured properties compare quite well electrical transport in berea 500 sandstone is complicated by the presence of surface conduction in the electric double layer at the grain electrolyte boundary a three phase conductivity model is proposed to compute surface conduction on the rock ct image effects of image resolution and computation sample size on the accuracy of numerical predictions are also investigated reducing resolution i e increasi

self potential monitoring of a salt plume nonintrusively monitoring the spread of contaminants in real time with a geophysical method is an important task in hydrogeophysics we have developed a sandbox experiment showing that the self potential method can locate both the source of leakage and the front of a contaminant plume we monitored the leakage of a plume of salty water from a hole at the bottom of a small tank located at the top of a main sandbox initially the sand was saturated by tap water at a given time a hole was opened at the bottom of the tank allowing the salty water to migrate by diffusion and buoyancy driven flow in the main sandbox the bottom of the sandbox contained a network of 32 nonpolarizing silver silver chloride electrodes with amplifiers connected to a multichannel voltmeter the self potential response associated withthe migration of the salt plume in the sandbox was recorded over time a self potential anomaly was observed with amplitude varying from a few millivolts at the start of the leak to a few tens of mi

rb sr sm nd and pb isotope systematics of pyrite implications for the age and genesis of lode gold deposits lode gold deposits commonly consist of pyrite and lesser amounts of lead and zinc sulfides accompanied by quartz and calcite their exact origin remains controversial mainly because of the scarcity of reliable geochronological data here we present direct rb sr dating of pyrite from a lode gold deposit and propose the method as a useful geochronological technique for gold mineralization for which age data are poor a positive correlation between present day 87 sr 86 sr and 87 rb 86 sr ratios of pyrite fes 2 subsamples from the linglong gold mine of china corresponds to an age of 122 123 ma which dates the age of gold mineralization the sr nd and pb isotopic compositions of pyrites and the associated rocks suggest that the hydrothermal fluids responsible for the pyrite and gold mineralization were probably derived from a mixed source i e degassing of mafic magmas and meteoric water that had leached the country rocks

pattern and forcing of northern hemisphere glacier variations during the last millennium time series depicting mountain glacier fluctuations in the alps display generally similar patterns over the last two centuries as do chronologies of glacier variations for the same interval from elsewhere in the northern hemisphere episodes of glacier advance consistently are associated with intervals of high average volcanic aerosol production as inferred from acidity variations in a greenland ice core advances occur whenever acidity levels rise sharply from background values to reach concentrations 1 2 equiv h kg above background a phase lag of about 10 15 yr equivalent to reported response lags of alpine glacier termini separates the beginning of acidity increases from the beginning of subsequent ice advances a similar relationship but based on limited and less reliable historical data and on lichenometric ages is found for the preceding 2 centuries calibrated radiocarbon dates related to advances of non calving and non surging glaciers during the earlier part of the little ice age display a comparable consistent pattern an interval of reduced acidity values between about 1090 and 1230 a d correlates with a time of inferred glacier contraction during the medieval optimum the observed close relation between noothern hemisphere glacier fluctuations and variations in greenland ice core acidity suggests that sulfur rich aerosols generated by volcanic eruptions are a primary forcing mechanism of glacier fluctuations and therefore of climate on a decadal scale the amount of surface cooling attributable to individual large eruptions or to episodes of eruptions is simlar to the probable average temperature reduction during culminations of little ice age alacier advances ca 0 5 1 2 c as inferred from depression of equilibrium line altitudes

fluid circulation in a complex volcano tectonic setting inferred from self potential and soil co2 flux surveys the santa maria cerro quemado zunil volcanoes and xela caldera northwestern guatemala the region encompassing santa maria cerro quemado and zunil volcanoes close to quetzaltenango the second largest city of guatemala is volcanically and tectonically complex in addition the huge xela caldera about 20 km in diameter crosses this area and links up to the important zunil fault zone located between the three volcanoes two highly active geothermal sites named zunil i and zunil ii are also located between these three volcanic edifices at the southeastern boundary of xela caldera in order to determine the permeability variations and the main structural discontinuities within this complex volcano tectonic setting self potential and soil co2 flux measurements have been coupled with a step of 20 m along a 16 880 km long profile crossing the entire area two shallow hydrothermal systems with maximum lateral extensions of 1 5 km in diameter are indicated by positive self potential elevation gradients below santa maria and cerro quemado volcanoes such small hydrothermal systems cannot explain the intense geothermal manifestations at zunil i and zunil ii another minor hydrothermal system is indicated by self potential measurements on the flank of santa maria along the edge of the xela caldera co2 flux measurements display slight variations inside the caldera and decreasing values crossing outside the caldera boundary we hypothesize the presence of a magmatic body inside the southeastern border of xela caldera to explain the deeper and more intense hydrothermal system manifested by the zunil i and the zunil ii geothermal fields this magmatic system may be independent from santa maria and cerro quemado volcanoes alternatively the hypothesized xela magmatic system could have a common magmatic origin with the cerro quemado dome complex consistent with previous findings on regional gas emissions sectors bordering the cerro quemado dome complex also have high amplitude minima short wavelength anomalies in self potential interpreted as preferential rain water infiltration along faults of major permeability probably related with the most recent stages of cerro quemado dome growth

identification of water bearing fractures in hard rock terrain by electrical conductivity logs india for the delineation of water bearing fractures in hard rock areas a new hydro chemical technique has been developed which is based on electrical conductivity ec logs the ec logs were carried out in experimental shallow bore wells 50 m in three different parts of india a sharp variation in ec was observed near water bearing fractures in hard rock areas to access applications of this technique different locations in india were selected and experimental bore wells 50 m were drilled these were 1 maheswaram 30 km south of hyderabad nine shallow bore wells in a watershed of 60 km2 in granitic aquifers 2 wailpally 60 km east of hyderabad four shallow bore wells in a watershed of 50 km2 in granitic terrain 3 sadras 60 km ssw of chennai four shallow bore wells in a watershed 12 km2 in a charnokite aquifers observations on ec logs were made at short intervals of 1 0 m from the water table narrow spacing wherever required until reaching the bottom of the wells ec showed remarkable changes in value which was attributed to the presence of water bearing fractures in the hard rock areas the results of this study are in good agreement with geophysical and geological findings in addition to identifying the water bearing fractures the ec logs also provide various other hydrological and hydrochemical information i e water table total depth of the bore well total dissolved solids tds behavior of water rock interaction water quality information about the chemistry of aquifers etc

high temperature geochronology constraints on the tectonic history and architecture of the ultrahigh pressure dabie sulu orogen 1 new u pb zircon and th pb monazite ages are presented from the giant sulu ultrahigh pressure uhp terrane combined with sm nd ages rb sr ages inclusion relationships and geologic relationships they help define the timing of peak recrystallization the timing of subsequent amphibolite facies metamorphism and the architecture of the dabie sulu suture zone between the collided sino korean and yangtze cratons the data indicate a 15 myr record of uhp recrystallization the first clearly documented for a giant uhp terrane this requires that continental subduction in the dabie sulu orogen involved multiple uhp tectonic or recrystallization events a 244 236 ma precursor uhp event seen only in the dabie shan was followed by a second 230 220 ma main uhp event which was itself terminated by a 220 205 ma amphibolite facies overprint older eclogite facies events seen in the qinling segment of this orogenic belt raise the possibility that these rocks have undergone u hp metamorphism three or four times but at present there is no geochronological evidence in the dabie sulu area to support this the subduction of the lower yangtze plate did not proceed in a simple fashion the ages of inherited zircon cores demonstrate that a ribbon continent of yangtze affinity escaped subduction and became wedged against the sino korean plate hanging wall

pattern of shallow ground water flow at mount princeton hot springs colorado using geoelectrical methods abstract in geothermal fields open faults and fractures often act as high permeability pathways bringing hydrothermal fluids to the surface from deep reservoirs the mount princeton area in south central colorado is an area that has an active geothermal system related to faulting and is therefore a suitable natural laboratory to test geophysical methods the sawatch range front normal fault bordering the half graben of the upper arkansas valley is characterized by a right lateral offset at mount princeton hot springs this offset is associated with the chalk cliffs of hydrothermally altered quartz monzonite because fault identification in this area is complicated by quaternary deposits including glacial and fluvial deposits we use dc electrical resistivity tomography and self potential mapping to identify preferential fluid flow pathways the geophysical data over 5600 resistivity and 2700 self potential measurements provide evidence of the existence of a dextral strike slip fault zone fault b responsible for the offset of the sawatch fault a segment of this dextral strike slip fault termed u1 is acting as the dominant vertical flow path bringing thermal waters to a shallow unconfined aquifer upwelling of the thermal waters is also observed at two zones u2 and u3 of an open fracture called fault a this fault is located at the tip of the sawatch fault and is likely associated with an extensional strain regime in this area self potential measurements are used to estimate the flux of upwelling thermal water the upflow estimate 4 1 10 3 m 3 day for the open segment of the fault b and 2 1 10 3 m 3 day for fault a from the geophysical data is remarkably consistent with the downstream mt princeton hot water production 4 3 4 9 10 3 m 3 day at approximately 60 86 c a temperature map indicates that a third upwelling zone termed u4 may exist at the southern tip of the sawatch fault

self potential signals associated with variations of the hydraulic head during an infiltration experiment 1 a field experiment was performed to monitor the variations of the hydraulic head in the vicinity of a ditch during a water infiltration experiment and using the self potential method the coupling between electric and hydraulic flows is electrokinetic in nature the electrical signals are measured at the ground surface with a set of ten non polarisable petiau pb pbcl2 electrodes over a section perpendicular to the ditch the electrical potential is linearly related to the depth of the water table which is here quite shallow between 1 to 2 m a rough estimate of the electrokinetic coupling coefficient obtained in the field is 10 mv per meter of hydraulic head 1000 mv mpa 1 of pore fluid pressure the order of magnitude of this estimate agrees with a laboratory experiment performed with a soil sample from the test site the good correlation found between electrical potential and hydraulic head variations opens the door to direct tomography of hydraulic head fluctuations with many innovative applications in hydrogeology especially because the potential depth to which this method could be applicable is high several hundred meters

delineation of shallow resistivity structure around malvan konkan region maharashtra by neural network inversion using vertical electrical sounding measurements modeling resistivity profiles especially from hard rock areas is of specific relevance for groundwater exploration a method based on bayesian neural network bnn theory using a hybrid monte carlo hmc simulation scheme is applied to model and interpret direct current vertical electrical sounding measurements from 28 locations around the malvan region in the sindhudurg district southwest india the modeling procedure revolves around optimizing the objective function using the hmc based sampling technique which is followed by updating each trajectory by integrating the hamiltonian differential equations via a second order leapfrog discretization scheme the inversion results suggest a high resistivity structure in the north western part of the area which correlates well with the presence of laterites in the south western part a very high conductive zone is observed near the coast indicating an extensive influence of saltwater intrusion our results also show that the effect of intrusion of saline water diminishes from the south western part to the north eastern part of the region two dimensional modeling of four resistivity profiles shows that the groundwater flow is partly controlled by existing lineaments fractures and major joints groundwater occurs at a weathered semi weathered layer of laterite clayey sand and the interface of overburden and crystalline basement the presence of conduits is identified at a depth between 10 and 15 m along the dhamapur kudal and parule oros profiles which seems to be potential zone for groundwater exploration the nw se trending major lineaments and its criss cross sections are indentified from the apparent and true resistivity surface map the pseudo section at different depths in the western part of the area near parule shows extensive influence of saltwater intrusion and its impact reaching up to a depth of 50 m from the surface along the coastal area further the deduced true electrical resistivity section against depth correlates well with available borehole lithology in the area present analyses suggest that hmc based bnn method is robust for modeling resistivity data especially in hard rock terrains these results are useful for interpreting fractures major joints and lineaments and crystalline basement rock and also for constraining the higher dimensional models

hydrodynamic parameters estimation from self potential data in a controlled full scale site abstract a multi physical approach developed for the hydrodynamic characterization of porous media using hydrogeophysical information is presented several pumping tests were performed in the hydrogeosite laboratory a controlled full scale site designed and constructed at the cnr imaa consiglio nazionale delle ricerche istituto di metodologia per l analisi ambientale in marsico nuovo basilicata region southern italy in order to obtain an intermediate stage between laboratory experiments and field survey the facility consists of a pool used to study water infiltration processes to simulate the space and time dynamics of subsurface contamination phenomena to improve and to find new relationship between geophysical and hydrogeological parameters to test and to calibrate new geophysical techniques and instruments therefore the hydrogeosite laboratory has the advantage of carrying out controlled experiments like in a flow cell or sandbox but at field comparable scale the data collected during the experiments have been used to estimate the saturated hydraulic conductivity k s ms 1 using a coupled inversion model working in transient conditions made up of the modified richards equation describing the water flow in a variably saturated porous medium and the poisson equation providing the self potential v which naturally occurs at points of the soil surface owing to the presence of an electric field produced by the motion of underground electrolytic fluids through porous systems the result obtained by this multi physical numerical approach which removes all the approximations adopted in previous works makes a useful instrument for real heterogeneous aquifer characterization and for predictive analysis of its behavior

40ar 39ar age gradients in micas from a high temperature low pressure metamorphic terrain evidence for very slow cooling and implications for the interpretation of age spectra estimates of the time temperature history of geologic samples are often based on 40 ar 39 ar ages obtained through incremental heating experiments on minerals with different ar retentivities laser incre mental heating of single crystals of muscovite and biotite from an 1700 ma monzogranite from a low pressure high temperature metamorphic terrain in central arizona suggested an essentially uniform distribution of radiogenic 40 ar in each crystal and yielded ages of 1412 5 ma for the muscovite and 1410 10 ma for the biotite the similarity in these ages implies rapid 25 k m y cooling of the monzogranite after a reheating episode slightly before 1412 ma in contrast detailed age mapping of single crystals from the same samples with the laser microprobe revealed large radiogenic 40 ar gradients indicative of very slow 400 m y evidence for such low cooling rates has important implications for the longevity of high thermal gradients in the early middle proterozoic lithosphere in addition inconsistency between the laser mapping and incremental heating results for these micas suggests caution when interpreting incremental heating data for slowly cooled samples

the volcano electric effect 1 the formation of a magmatic intrusion at depth is responsible for the formation of various thermohydromechanical thm disturbances including the upsurge of shock waves and diffusion of pressure fronts in the volcanic system we couple electromagnetic theory maxwell equations and thermoporoelasticity biot equations to look at the ground surface electrical signature of these thm disturbances the nature of this coupling is electrokinetic i e associated with water flow relative to the mineral framework and the drag of the excess of charge located in the vicinity of the pore water mineral interface the groundwater flow disturbance being related here to the thm disturbances in drained conditions a new set of laboratory data shows that the electrokinetic coupling is very substantial in fractured basaltic and volcaniclastic materials and in scoria with several hundreds of millivolts of electrical potential gradient produced per megapascal of pore fluid pressure variations our theoretical analysis predicts the diffusion of electromagnetic disturbances and quasi static electrical signals these signals can be used as precursors of a volcanic eruption indeed electromagnetic phenomena recorded at the ground surface of a volcanic system once properly filtered to remove external contributions provide a direct and quasi instantaneous insight into the thm disturbances occurring in the heart of the volcanic structure prior and during a volcanic event tomography of the quasi static electrical field is discussed and applied to self potential profiles performed at the piton de la fournaise volcano during the preparation phase of the march 1998 eruption

identifying hydrologic flowpaths on arctic hillslopes using electrical resistivity and self potential shallow subsurface flow is a dominant process controlling hillslope runoff generation soil development and solute reaction and transport despite their importance the location and geometry of these flow paths are difficult to determine in arctic environments shallow subsurface flow paths are limited to a thin zone of seasonal thaw above permafrost which is traditionally assumed to mimic the surface topography we have used a combined approach of electrical resistivity tomography ert and self potential sp measurements to map shallow subsurface flow paths in and around water tracks drainage features common to arctic hillslopes ert measurements delineate thawed zones in the subsurface that control flow paths whereas sp is sensitive to groundwater flow we have found that areas of low electrical resistivity in the water tracks were deeper than manual thaw depth estimates and varied from the surface topography this finding suggests that traditional techniques might underestimate active layer thaw and the extent of the flow path network on arctic hillslopes sp measurements identify complex 3d flow paths in the thawed zone our results lay the groundwork for investigations into the seasonal dynamics hydrologic connectivity and climate sensitivity of spatially distributed flow path networks on arctic hillslopes

origin and evolution of ore fluid and gold deposition processes at the giant taishang gold deposit jiaodong peninsula eastern china abstract the early cretaceous taishang gold deposit is the largest deposit in the linglong goldfield jiaodong peninsula with a pre mining endowment of 326 t of gold it is hosted in the 165 150 ma linglong biotite granite and controlled by the nee to ne trending potouqing fault near the northern end of the regional zhaoping fault system hydrothermal alteration is well developed in the footwall of the potouqing fault and is characterized by a narrow zone of sericitization followed by a wider zone of silicification and an even wider zone of potassic alteration the main orebodies no i orebody comprise disseminated and stockwork veinlet systems although about 5 of the resources are in larger quartz veins no ii orebody four stages have been identified for both styles of mineralization on the basis of cross cutting relationships and mineralogical and textural characteristics pyrite quartz sericite stage 1 quartz pyrite stage 2 quartz pyrite base metal sulfide stage 3 and quartz carbonate stage 4 gold was mainly deposited in stages 2 and 3 with minor amounts in stage 1 petrographical microthermometric and laser raman spectroscopic studies on fluid inclusion assemblages in quartz and calcite from the four stages reveal three types of primary fluid inclusions type 1 h 2 o rich aqueous carbonic type 2 co 2 rich aqueous carbonic and rare type 3 carbonic inclusions stage 1 quartz primary inclusions are only type 1 inclusions with an estimated composition of 88 h 2 o 10 co 2 4 5 wt nacl equiv and 0 5 ch 4 with trapping at 336 c and 1 7 kbars the gold rich stages 2 and 3 from both orebodies typically contain primary fluid inclusion assemblages with both type 1 and 2 inclusions which show similar phase transition temperatures and were trapped between 246 and 294 c the stage 4 quartz and calcite contain only primary type 1 inclusions which are estimated to have a composition of 93 h 2 o 6 0 co 2 3 6 wt nacl equiv and trace amount of ch 4 and were trapped at temperatures of 236 c the 34 s values of hydrothermal pyrite from the four stages have a narrow range from 4 5 to 8 0 and are within the ranges for whole rock sulfides from the archean jiaodong group and magmatic pyrite from mesozoic granitoid and intermediate basic dikes the 18 o values of hydrothermal quartz range mainly from 10 9 to 12 5 and remain constant for all four stages calculated fluid 18 o values are 1 3 10 0 the d water values calculated from hydrothermal sericite range from 60 to 45 considering the fluid inclusion compositions 18 o and d compositions of ore forming fluids and regional geological events the most likely ultimate potential fluid and metal reservoirs would be the paleo pacific oceanic slab and its overlying sediments which were thrust below the high grade metamorphic rocks of the jiaodong peninsula the initial ore forming fluids were medium high temperature co 2 rich and low salinity h 2 o co 2 nacl ch 4 homogeneous fluids over the duration of the hydrothermal system the fluid remained fairly consistent in p t x although becoming slightly more water rich during final post ore activity fluid immiscibility occurred during stages 2 and 3 ore deposition at pressures that fluctuated strongly from 1700 to 580 bars during hydrofracturing the hs 2 ion was the most probable gold transporting complex at taishang wall rock sulfidation and episodic pressure drops with associated fluid unmixing and other chemical changes were the two main mechanisms of ore deposition

methods for assessing and forecasting the survival of north cascade washington glaciers abstract north cascade glacier annual balance measured on 10 glaciers from 1984 to 2009 yielded mean annual balance ba of 0 51 m y and 13 26 m cumulatively this is a significant loss for glaciers that average 30 60 m in thickness 20 40 of their entire volume this rapid volume loss has led to the complete loss of two glaciers spider and lewis glacier this indicates the need for a method of forecasting glacier survival in the region temperate alpine glacier survival is dependent on the consistent presence of an accumulation zone if a glacier does not have a persistent accumulation zone all areas of the glacier will experience thinning including the former accumulation zone examination of the accumulation zone can identify thinning from substantial marginal recession emergence of new rock outcrops and surface elevation declines in the accumulation zone nine of the 12 north cascade glaciers examined exhibit these characteristics each glacier that exhibited accumulation zone thinning features also had frequent low annual accumulation area ratio values below 0 30 this indicates the lack of a persistent accumulation zone

anomalies of noble gases and self potential associated with fractures and fluid dynamics in a horizontal borehole mont terri underground rock laboratory abstract before the excavation of the new gallery ga08 in the mont terri underground rock laboratory switzerland which joined the existing gallery ga04 in 2008 the end face of gallery ga04 was instrumented in 2007 to characterize the evolution of the rock mass with geochemical and geophysical methods the noble gas content of a 12 m long horizontal borehole evidenced that desaturation processes occurred in the first 2 m where pre existing fractures accommodated the stress change during excavation of gallery ga04 four years before these first 2 m are associated with the so called excavation damaged zone edz as an inflow of pore water was observed in this borehole few weeks after its drilling continuous self potential sp measurements were performed to characterize its dynamics after the drilling of new sub horizontal boreholes in the end face strong localized variations of sp occurred the comparison with the geological features of the rock mass suggests that these dynamic anomalies have to be associated with fluid circulation in pre existing tectonic fractures that were primarily reactivated by the excavation of the gallery ga04 and subsequently by the drilling operations

estimating aquifer hydraulic properties from the inversion of surface streaming potential sp anomalies 1 electrokinetic effects of water flow during pumping tests have been shown to generate surface streaming potential sp anomalies of several tens of mv that are well correlated with the geometry of the water table it follows that sp measurements can be used to estimate aquifer hydraulic properties we have developed an inversion scheme for surface sp data generated by flow pumping and found that we are able to estimate the hydraulic conductivity and the depth and the thickness of the aquifer we applied our inversion scheme to the data from bogoslovsky and ogilvy 1973 and found a hydraulic conductivity of 10 5 m s 1 an aquifer thickness of roughly 28 m and an electrokinetic coupling coefficient of 1 mv m 1 these values are in the range of what is expected for this kind of environment

the current disequilibrium of north cascade glaciers three lines of evidence indicate that north cascade washington usa glaciers are currently in a state of disequilibrium first annual balance measured on nine glaciers yields a mean cumulative balance for the 1984 2004 period of 8 58 m water equivalent w e a net loss of ice thickness exceeding 9 5 m this is a significant loss for glaciers that average 30 50 m in thickness representing 18 32 of their entire volume second longitudinal profiles completed in 1984 and 2002 on 12 north cascade glaciers confirm this volume change indicating a loss of 5 7 to 6 3 m in thickness 5 0 5 6 m w e between 1984 and 2002 agreeing well with the measured cumulative balance of 5 52 m w e for the same period the change in thickness on several glaciers has been equally substantial in the accumulation zone and the ablation zone indicating that there is no point to which the glacier can retreat to achieve equilibrium substantial thinning along the entire length of a glacier is the key indicator that a glacier is in disequilibrium third north cascade glacier retreat is rapid and ubiquitous all 47 glaciers monitored are currently undergoing significant retreat or in the case of four have disappeared two of the glaciers where mass balance observations were begun spider glacier and lewis glacier have disappeared the retreat since 1984 of eight mount baker glaciers that were all advancing in 1975 has averaged 297 m these observations indicate broad regional continuity in glacial response to climate copyright 2006 john wiley sons ltd

stochastic bayesian inversion of borehole self potential measurements summary we propose a mechanistic model to compute and to invert self potential log data in sedimentary basins and for near surface geophysical applications the framework of our analysis is founded in a unified electrical conductivity and self potential petrophysical model this model is based on an explicit dependence of these properties on porosity water saturation temperature brine salinity cementation and saturation archie exponents and the volumetric charge density per unit pore volume associated with the clay fraction this model is consistent with empirical laws widely used to interpret self potential logs according to the two limiting cases corresponding to a clean sand and a pure shale we present a finite element calculation of the self potential signal produced by sand reservoirs interstratified with shale layers for layered strata normal to the well we demonstrate that the 3 d poisson equation governing the occurrence of self potentials in a borehole can be simplified to a 2 d axisymmetric partial differential equation solved at each depth providing a common self potential reference can be defined between these different depths this simplification is very accurate as long as the vertical salinity gradients are not too strong over distances corresponding to the borehole diameter the inversion of borehole data self potential resistivity and density well logs incorporating information derived from neutron porosity and gamma ray log data is performed with the adaptive metropolis algorithm ama we start by formulating an approximate analytical solution for the six model parameters water saturation porosity the two archie s exponents the pore water conductivity and the volumetric charge density of the diffuse layer this solution is used for the ama algorithm to converge in less than 60 iterations at each depth for the real case study the posterior probability distributions are computed using 50 60 additional realizations our approach is applied to a case study concerning a small sedimentary sequence in the piceance basin colorado in a series of tight gas reservoirs

hydroelectric coupling in a clayey material the hydroelectric coupling generating self potential anomalies recorded on the earth s surface has received a considerable attention in the last four years geophysical applications include the use of this phenomenon for mapping subsurface fluid flow the study of hydrothermal activity and the use of self potential anomalies to monitor volcanic activity and the possibility still debated of seismic activity forecasting through the use of electromagnetic precursors of electrokinetic nature we model here two key parameters relevant of the hydroelectric coupling in clayey porous rocks these two parameters are the potential and the specific surface conductivity which depend on the electrochemistry of the pore water mineral interface they are modeled in the case of a kaolinite saturated by a nacl brine using a triple layer model tlm in which the parameters are optimized using the simplex algorithm

principles of electrography applied to self potential electrokinetic sources and hydrogeological applications 1 the electrical potential field passively recorded at the ground surface of the earth and termed self potential can be analyzed to determine the shape and the depth of the piezometric surface the coupling between hydraulic flow and electrical current density is electrokinetic in nature the electrokinetic coupling coefficient entering into the integral equation relating the depth of the water table to self potential signals is analyzed for various types of porous materials it is simply related to the electrical conductivity of the pore water in steady state conditions each element of the water table can be seen as an elementary dipole with an inclination locally perpendicular to the water table and strength proportional to the water table elevation then we propose three methods to obtain the shape and range of possible depths of the water table from the study of the self potential distribution recorded at the ground surface the nonuniqueness of the solution is removed if one knows either the electrokinetic coupling coefficient or the water table at one location and under the assumption of the spatial homogeneity of the electrokinetic coupling coefficient two field cases are discussed to show the success of the proposed methods for estimating the shape and depth of the water table at two different scales of investigations they concern the study of self potential signals associated with the shape of the water table in the vicinity of a pumping well and in the flank of the kilauea volcano

origin of the jiaodong type xinli gold deposit jiaodong peninsula china constraints from fluid inclusion and c d o s sr isotope compositions abstract the xinli gold deposit within the sanshandao cangshang gold belt in the jiaodong gold province is a typical jiaojia type ore deposit with high grade quartz sulfide vein veinlet stockworks that cut mesozoic granodiorite four ore stages are distinguished in the following sequences i quartz k feldspar sericite pyrite ii quartz pyrite iii quartz polymetallic sulfide and iv quartz calcite pyrite fluid inclusions in quartz and calcite in the ores contain c o h fluids dominantly of six types with varied liquid vapor ratio ore fluid in the main ore stage is characterized by medium low temperature low salinity reducing condition and nacl h 2 o co 2 ch 4 in composition the 18 o water smow of quartz in ore stages ii and iii range from 2 82 to 5 34 and the d smow are between 69 6 and 88 3 both suggest that the ore fluid was dominantly magmatic water the 13 c pdb of the calcite are from 6 4 to 2 4 indicating mantle contribution to the ore fluid the pyrite 34 s cdt from four ore stages are basically similar varying from 9 42 to 11 62 which implies significant involvement of crustal materials the initial 87 sr 86 sr ratios in the calcite ranging from 0 710657 to 0 711542 also denote a crustal contribution the fluid composition and systematic h o c s sr isotopic data are explained by a model of slab subduction induced gold mineralization in the model the ore fluid and metals were considered to associate with the dehydration and desulfidation of the subducting paleo pacific slab and the subsequent devolatilization of enriched mantle wedge the h 2 o in the fluid might have been released from the devolatilization of enriched mantle wedge the co 2 could be from mantle wedge or subcontinental lithospheric mantle and the sulfur and strontium would be initially released from the subducted seafloor sediments this process was further supported by the geochemical features of intermediate basic dykes contemporaneous to the gold ore deposits the deposit features and ore forming process of the xinli gold deposit hardly concur those of the orogenic gold deposit and the pluton related gold deposit the study supports the argument of that the gold deposits in the jiaodong belong to a unique gold type related to a complex slab subduction related process the geodynamic engine of the jiaodong type gold deposit is specific i e the slab subduction coupling with the consequent lithospheric thinning and structure adjustment

geology and timing of mineralization at the cangshang gold deposit north western jiaodong peninsula china the cangshang gold deposit of the north western jiaodong peninsula contains reserves of greater than 50 tonnes t and is developed by the largest open pit gold mine in china this deposit is a jiaojia style i e disseminated and veinlet deposit it is controlled by the san cang fault zone which trends 040 and dips 40 75 se at the mine site the main no 1 orebody lies between a hanging wall of precambrian metamorphic rocks mainly amphibolite of the fenzishan group and a footwall composed of the mesozoic linglong granitoid the ore zone is mainly composed of pyritized sericitized and silicified granitoid which has undergone variable degrees of cataclasis shrimp u pb dating of zircon indicates that the protolith of the hanging wall amphibolite was formed at 2530 17 ma and underwent metamorphism at 1852 37 ma the footwall granodiorite has been dated at 166 4 ma whereas zircons from the ore zone yield a younger age of 154 5 ma cathodoluminescence images of zircons from the granodiorite and ore zone show oscillatory zonation indicative of an igneous origin for both and the ages of these zircons therefore are all interpreted to be representative of magmatic crystallization dating of sericite by 40ar 39ar has been used to directly determine the timing of formation of the cangshang deposit providing the first time absolute age on formation of the jiaojia style gold deposits the well defined age of 121 3 0 2 ma provides the precise timing of gold mineralization at the cangshang deposit this age is consistent with those of linglong style vein type gold mineralization also from the north western jiaodong peninsula at between 126 and 120 ma therefore our work indicates that both styles of gold deposits in the jiaodong peninsula were formed during the same mineralization event

adventive hydrothermal circulation on stromboli volcano aeolian islands italy revealed by geophysical and geochemical approaches implications for general fluid flow models on volcanoes on march 15th 2007 a paroxysmal explosion occurred at the stromboli volcano this event generated a large amount of products mostly lithic blocks some of which impacted the ground as far as down to 200 m a s l about 1 5 km far away from the active vents two days after the explosion a new vapour emission was discovered on the north eastern flank of the volcanic edifice at 560 m a s l just above the area called nel cannestra this new vapour emission was due to a block impact in order to investigate the block impact area to understand the appearance of the vapour emission we conducted on may 2008 a multidisciplinary study involving electrical resistivity tomography ert ground penetrating radar gpr self potential sp co2 soil diffuse degassing and soil temperature surveys this complementary data set revealed the presence of an anomalous conductive body probably related to a shallow hydrothermal level at about 10 15 m depth more or less parallel to the topography it is the first time that such a hydrothermal fluid flow with a temperature close to the water boiling point 76 c has been evidenced at stromboli at this low elevation on the flank of the edifice the ert results suggest a possible link between 1 the main central hydrothermal system of stromboli located just above the plumbing system feeding the active vents with a maximum of subsurface soil temperature close to 90 c and limited by the neostromboli summit crater boundary and 2 the investigated area of nel cannestra at 500 m a s l a buried eruptive fissure active 9 ka ago in parallel sp and co2 soil diffuse degassing measurements suggest in this sector at slightly lower elevation from the block impact crater a magmatic and hydrothermal fluid rising system along the n41 regional fault a complementary ert profile on may 2009 carried out from the neostromboli crater boundary down to the block impact crater displayed a flank fluid flow apparently connected to a deeper system the concept of shallow hydrothermal level have been compared to similar ert results recently obtained on mount etna and la fossa cone of vulcano this information needs to be taken into account in general fluid flow models on volcanoes in particular peripheral thermal waters as those bordering the north eastern coast of stromboli could be contaminated by hydrothermal and magmatic fluids coming from regional faults but also from the summit

constitutive equations for ionic transport in porous shales 1 the constitutive coupled equations describing ionic transport in a porous shale are obtained at the scale of a representative elementary volume by volume averaging the local nernst planck and stokes equations the final relationships check the onsager reciprocity to the first order of perturbation of the state variables with respect to the thermostatic state this state is characterized by a modified version of the donnan equilibrium model which accounts for the partition of the counterions between the stern and diffuse gouy chapman layers after upscaling the local equations the material properties entering the macroscopic constitutive equations are explicitly related to the porosity of the shale its cation exchange capacity and some textural properties such as the electrical cementation exponent entering archie s law this new model is then applied to predict the salt filtering and electrodiffusion efficiencies of a shale layer

estimation of hydraulic conductivity and water table map in a large scale laboratory model by means of the self potential method 1 the goal of this paper is to estimate the position of the water table and hydraulic conductivity of a homogeneous porous medium by means of the self potential method the hydrogeophysical experiments were carried out at the hydrogeosite laboratory of the istituto di metodologie per l analisi ambientale consiglio nazionale delle ricerche marsico nuovo italy the laboratory is a large scale model sized 10 7 3 m3 that is filled with a homogeneous medium made up of quartz rich sand with a medium high hydraulic conductivity in the order of 10 5 m s 1 self potential signals generated by the groundwater flow during a pumping test were measured on the ground surface on both the pumping and the recovery phases a novel methodology to estimate the hydraulic conductivity from self potential measurements is proposed hydraulic conductivity very close to that calculated from hydraulic data by means of neuman type curves has been obtained by solving the electrical flow equation through a linear least squares method moreover a kriging with external drift geostatistical methodology has been proposed to estimate the hydraulic head distribution the advantages given by this geostatistical method are that 1 hydraulic head distribution can be estimated without any previous electrokinetic coupling coefficient calculation and 2 the method is valid for either linear or nonlinear relationships between self potential and hydraulic head gradients an original finding of this work is that the relationship between self potential signals and drawdown around a pumping well is not always linear linearity applies only when the groundwater velocity is low but high nonlinearity occurs when hydraulic head gradient rises up kriging with the external drift method could be used for the inversion of the hydraulic conductivity distribution in a real heterogeneous aquifer by means of an appropriate conditioning technique

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

2d self potential tomographies for studying groundwater flows in the varco d izzo landslide basilicata southern italy abstract a geoelectrical monitoring activity has been carried out to improve the geological and hydrogeological knowledge about the varco d izzo landslide potenza basilicata southern apennine italy an active rotational translational slide evolved in earth flow in this work we have focused on the self potential sp method by applying three different sp measuring techniques and combining modern technologies for data acquisition and new methods for tomographic inversion a sp map and three static sp tomographies have been carried out to better analyse the groundwater circulation system and to better reconstruct the geometry of the landslide body in the accumulation zone which is the area more exposed to the geomorphological activity a new sp measuring strategy has been applied this strategy based on time continuous 2d sp tomographies helps identify water flow changes in subsurface by studying the time series of sp tomographic images the analysis of time dependent changes of water infiltration in near surface is the key to better understand the hydrogeological processes underlying the ground instability phenomena the time lapse analysis of tomographic images has allowed us not only to investigate the correlation between the temporal changes of sp signals and rainfall events but also to quantify the range of these changes the modification of the distribution of the sp source accumulation zones is associated with the dynamics of the groundwater flows these preliminary results allow us to consider the sp tomographic method as a tool for geophysical monitoring of landslide areas and encourage to develop new measuring systems for near real time applications

decratonic gold mineralization evidence from the shangzhuang gold deposit eastern north china craton abstract the jiaodong peninsula in the eastern north china craton ncc hosts some of the world class gold deposits among these the shangzhuang gold deposit represents a typical fault zone hosted disseminated and stockwork style gold mineralization the mineralization is characterized by intense hydrothermal alteration halos in the wallrocks with the mineralized veins intruding into altered wallrocks zircon u pb isotope dating constrains the timing of emplacement of the guojialing granodiorite as 130 1 ma five molybdenite samples from the main mineralization stage veins yielded a well fitted isochron age of 126 2 ma mswd 1 3 marking the timing of gold mineralization four types of fluid inclusions are identified at shangzhuang and their petrographic and microthermometric features suggest fluid immiscibility followed by fluid mixing this inference is also supported by oxygen and hydrogen isotopic data of quartz veins from stage iii the measured 18 o values of quartz are 12 3 to 13 7 for stage ii and 11 7 to 12 0 for stage iii with calculated 18 o fluid values for stage ii ranging from 5 9 to 7 3 and for stage iii from 3 4 to 3 7 d values for stage ii and iii quartz range from 65 3 to 75 2 and 70 6 to 74 7 respectively the data suggest that the ore forming fluids were initially derived from magmatic sources followed by mixing with meteoric water sims in situ sulfur isotope analyses of two types of pyrite py i and py ii from different mineralization stages show different sulfur isotope features the 34 s values for py i 10 2 to 11 3 mean 10 8 n 25 are higher than those of the later mostly gold related py ii 4 1 to 6 8 mean 5 4 n 27 the higher 34 s values of py i are correlated to degassing of mantle wedge metasomatized by the slab fluids the relatively lower 34 s values of py ii might suggest increasing of f o2 through fluid mixing between ore forming fluids and meteoric water the temporal spatial and tectonic relations between the giant gold mineralization and destruction of the ncc suggest a genetic linkage the gold mineralization between 126 and 117 ma at jiaodong was probably initiated at the peak of decratonization ca 125 ma of the eastern ncc phanerozoic craton margin orogeny also played a critical role in the generation of the early cretaceous giant gold deposits in the eastern ncc integrated geological characteristics mineralization features metallogenic age sources of ore forming fluids and sulfur and tectonic settings favor a decratonic gold mineralization model for the shangzhuang gold deposit the geodynamic scenario proposed for the early cretaceous giant gold mineralization event in the eastern ncc includes the paleo west pacific plate subduction asthenospheric upwelling multiple subduction collision processes along the margins

ann based inversion of dc resistivity data for groundwater exploration in hard rock terrain of western maharashtra india summary inversion of vertical electrical sounding ves data especially from the crystalline hard rock area assumes a special significance for groundwater exploration here we used a newly developed algorithm based on the bayesian neural network bnn theory combined with hybrid monte carlo hmc markov chain monte carlo mcmc simulation scheme to invert the direct current dc ves measurements obtained from 30 locations around tenduli vengurla sindhudurg district maharashtra india the inversion results suggest that the top layer is mostly comprised of laterites followed by mixture of clay clayey sand and garnulites granite as basement rocks the source of groundwater appears to be accessible in weathered semi weathered layer of laterite clayey sand that exists within the depth of 10 15 m from the surface the nw se trending major lineaments and its criss crosses are also identified from the apparent and true resistivity surface map the pseudo section at different depths in the western part of the area near nivti shows extensive influence of saltwater intrusion and its impact reaching up to the depth of 30 m from the surface along the coastal area our results also show that intrusion of saline water decreases from the western part to the eastern part of the region two dimensional modeling of four resistivity profiles from the study region identified two potential groundwater reservoirs one lying between path tenduli and another in between mat and zaraph the deduced true electrical resistivity section against depth correlates well with available borehole lithology in the area the results presented here would be useful for interpreting the geological signatures like fractures major joints and lineaments which in turn will be helpful for identifying groundwater reservoirs and drainage pattern in the crystalline hard rock area the newly developed hmc based bnn method is robust and would provide insights for constraining the geophysical models and criteria for modeling resistivity data

mineralization age and geodynamic background for the shangjiazhuang mo deposit in the jiaodong gold province china abstract the shangjiazhuang mo deposit is located on the jiaodong peninsula in eastern china which is famous for the ca 120 ma jiaodong type au deposits with total au endowment of over 3000 t in this paper we discuss the deposit geology mineralization age and geochemical features of the host granodiorite of the shangjiazhuang mo orebody using this information we aim to clarify the time and geodynamic mechanism for the mo deposit which is another constraint to understand the genesis of au deposits the mo mineralization generally occurs as quartz sulfide veins within the medium grained yashan granodiorite the alteration consists of potassic alteration silicification sericitization chloritization and carbonatization with a weak unclear zonation the ore minerals mainly include molybdenite chalcopyrite and pyrite we measured re os isotopes of molybdenite grains which yielded a weighted mean model age of 116 9 0 81 mswd 1 03 and a well constrained 187 re 187 os isochron age of 117 1 1 4 ma mswd 1 6 these ages are slightly younger than the age of au mineralization on the jiaodong peninsula rhenium contents of 5 84 29 99 ppm with an average of 16 4 ppm in molybdenites indicate a crustal source whole rock geochemical compositions show that the granodiorite is high k calc alkaline and metaluminous to peraluminous the samples show low y contents from 8 2 to 10 5 ppm and sr y ratios from 48 2 to 58 8 displaying an adakitic affinity the yashan granodiorite has high initial 87 sr 86 sr ratios of 0 7101 to 0 7104 low e nd t values of 17 6 to 16 7 and zircon e hf t values from 24 8 to 17 1 with corresponding hf model ages of 2 7 to 2 2 ga these isotopic data together with the adakitic affinity of the granodiorite indicate that the parental magma was derived from ancient crust mafic microgranular enclaves mme that are contemporaneous with the host granodiorite show sio 2 contents of 57 98 58 41 wt and depletion in nb ta the mmes show enriched initial 87 sr 86 sr ratios of 0 7102 to 0 7106 and low e nd t values of 17 3 to 16 3 the mmes are the products of mixing between the metasomatized lithospheric mantle derived mafic magma and the ancient crust derived felsic magma the early cretaceous mo mineralization 120 110 ma is slightly younger than the peak time of au mineralization 126 120 ma on the jiaodong peninsula but have a different spatial distribution which suggests different sources of au and mo the jiaodong type au deposits were probably related to the upwelling of metasomatized lithospheric mantle while the mo mineralization on the jiaodong peninsula may delineate a 120 110 ma mo metallogenic belt along the southern margin of the north china craton with the east qinling which is related to the melting of ancient crustal sources the subduction of the paleo pacific slab and accompanying asthenospheric upwelling triggered upwelling of metasomatized lithospheric mantle forming jiaodong type au deposits subsequently the ponding of mantle derived magmas resulted in partial melting of ancient crust and associated mo deposits

the buried caldera of misti volcano peru revealed by combining a self potential survey with elliptic fourier function analysis of topography abstract this survey proposes a new approach to identify buried caldera boundaries of a volcanic cone combining 1 a systematic elliptic fourier functions eff analysis on the contour lines based on the external shape of the edifice with 2 self potential sp measurements on volcano flanks the methodology of this approach is to investigate the relationships between 1 vertical morphological changes inferred from eff analysis and 2 lateral lithological transition inside the edifice inferred from sp elevation gradients the application of these methods on misti volcano in southern peru displays a very good correlation the three main boundaries evidenced by hierarchical cluster analysis on the contour lines coincide with the two main boundaries characterised by sp signal and with a secondary sp signature related with a summit caldera in order to explain these results showing a very good correlation between morphologic and lithologic changes as function of elevation caldera boundaries have been suggested the latter would be located at an average elevation of 1 4350 4400 m 2 4950 5000 m and 3 5500 5550 m for the lowest boundary in elevation the coincidence with the lateral extension of the hydrothermal system inferred from sp measurements suggests that caldera walls act as a barrier for lateral extension of hydrothermal systems in the summit area the highest boundary has been related with the summit caldera inferred by a secondary sp minimum and geological evidence

evidence for intracontinental thrust related exhumation of the ultra high pressure rocks in china coesite and diamond bearing ultra high pressure metamorphic rocks produced during the triassic continental collision between the sino korean and yangtze plates are offset by about 530 km along the sinistral tanlu fault in eastern china the tanlu fault terminates abruptly south of the ultra high pressure metamorphic terrain in dabie shan and does not extend into the foreland fold belt along the yangtze river this suggests that in this region the mesozoic major sinistral displacement along the tanlu fault was transferred to southward directed thrusting which led to the exhumation of the ultra high pressure metamorphic rocks formed earlier postcollisional himalayan type intracontinental thrusting and concomitant erosion appear to be the main agents in the exhumation of the very high pressure metamorphic rocks in china

40 ar 39 ar and u pb age constraints on the timing of gold mineralization in the kalgoorlie gold field western australia the 40 ar 39 ar ages of three hydrothermal muscovite samples associated with auriferous gold stockwork systems at the mount charlotte deposit in the kalgoorlie gold field have a weighted mean of 2602 or 8 ma 40 ar 39 ar age errors are 2sigma at the nearby golden mile deposit 40 ar 39 ar ages from two muscovite samples associated with shear hosted lode gold mineralization have a weighted mean of 2629 or 9 ma on the balance of available evidence these ages are interpreted to represent the timing of gold mineralization in the two deposits these data indicate that formation of auriferous gold stockwork systems at mount charlotte occurred at least 10 million years after formation of the gigantic golden mile lode system this is consistent with geologic relations between the two different styles of mineralization and suggests that separate hydrothermal episodes were responsible for stockwork and shear hosted gold mineralization a weighted mean 207 pb 206 pb zircon age for a postregional metamorphism biotite porphyry intrusion of 2674 or 6 ma 95 confidence limits provides a minimum estimate for the timing of regional metamorphism of the surrounding greenstone sequence and associated compressive deformation hypotheses for the formation of archcan gold deposits which invoke fluids that are derived from regional metamorphic devolatilization of upper middle crustal greenstone sequences or from intrusion of spatially related porphyries cannot account for the gold mineralization in the kalgoorlie gold field these data indicate that the events occurred 30 to 40 and 60 to 70 million years prior to mineralization at the golden mile and mount charlotte respectively formation of the golden mile appears to have been part of a widespread gold mineralizing event at ca 2630 to 2640 ma supporting models in which crustal scale hydrothermal circulation at this time is used to explain archcan gold mineralization within the yilgarn block however such models must now contain the caveat that discrete younger episodes of mineralization such as that responsible for mount charlotte may also produce significant gold deposits with features similar to typical archcan gold deposits

a comparison of jiaojia and linglong type gold deposit ore forming fluids do they differ abstract the jiaodong peninsula contains the most important concentration of gold deposits in china which can be divided into jiaojia type and linglong type deposits based on mineralization style the former is characterized by disseminated and stockwork style mineralization hosted in first order regional faults with relatively larger tonnages and lower gold grades the latter is characterized by massive auriferous quartz veins commonly hosted in subsidiary second or third order faults with smaller tonnage but higher grade orebodies despite these differences both groups of deposits have the same alteration assemblages mineral paragenesis element concentrations and ore forming ages the mainly jiaojia type luoshan gold deposit and the mainly linglong type fushan gold deposit are characterized by h o s pb isotope data that indicate the ore forming fluids have a dominantly metamorphic source the fluids were derived during the yanshanian orogenic event and were most likely associated with dehydration and decarbonization processes near the top of the subducting paleo pacific plate the linglong type ores have relatively lighter calculated 18 o compositions 3 9 to 2 3 than the jiaojia type ores 0 3 8 0 possibly because of a greater degree of mixing with meteoric water petrographic cathodoluminescence microthermometric and laser raman spectroscopic analyses of fluid inclusion assemblages in quartz from the two types of ores indicate fluids were similar in both cases characterized by medium high homogenization temperatures 211 393 c significant co 2 15 mol minor ch 4 18 in the carbonic phase and low salinity 11 2 wt nacl eq the linglong type ores however have a wider range of co 2 and ch 4 concentration and salinity than the jiaojia type ores fluid immiscibility occurred in main ore stage of both ore types with the trapping conditions of 77 185 mpa and 284 328 c although the unmixing is more intense and widespread in the linglong type ores both fluid wallrock interaction and fluid immiscibility are important gold deposition processes in the two types but immiscibility is more important in the linglong type ores and that has led to the typical higher gold grade in general there is little geochemical differences between the ore forming fluids for jiaojia and linglong type gold deposits both jiaojia and linglong type ores can exist in a single deposit and form in the same metallogenic event the linglong type ores developed as more massive veins because of their location in zones of more extensive extension and they lack significant post ore cataclastic deformation

three dimensional inversion of self potential data used to constrain the pattern of groundwater flow in geothermal fields 1 we propose an algorithm to invert self potential signals measured at the ground surface of the earth to localize hydromechanical disturbances or to the pattern of groundwater flow in geothermal systems the self potential signals result from the divergence of the streaming current density groundwater flow can be either driven by topography of the water table free convection or deformation of the medium the algorithm includes the electrical resistivity distribution of the medium obtained independently by dc resistance tomography or electromagnetic methods or by coding the assumed geology in terms of distribution of the electrical resistivity accounting for the effect of the temperature and salinity distributions and possibly constraints from borehole measurements inversion of the distribution of the source current density from ground surface and borehole self potential measurements is achieved by solving the inverse problem using tikhonov regularization solutions that are compatible with the physics of the primary flow problem by introducing assumptions regarding the smoothness or the compactness of the source and the three dimensional distribution of the electrical resistivity of the system the inverse problem can be solved in obtaining the three dimensional distribution of the current source density in the ground however an annihilator can be added to the inverted source geometry without affecting the measured self potential field annihilators can be obtained from boundary conditions synthetic models and a sandbox experiment are discussed to demonstrate the validity of the algorithm an application is presented to the geothermal field of cerro prieto baja california mexico using literature data inversion of the self potential and resistivity data allows observing a plume of hot groundwater rising to the ground surface in the central part of the investigated area and discharging to the ground surface in the southwest part the temperature anomaly associated with the existence of this plume is independently observed by interpolating borehole temperature measurements we found a good agreement between the distribution of the temperature and the inverted source current density the proposed method appears therefore as a noninvasive method for remote detection and three dimensional mapping of subsurface groundwater flow

terminus behavior and response time of north cascade glaciers washington u s a observation of the terminus behavior of 38 north cascade glaciers washington u s a since 1890 shows three different types of glacier response 1 continuous retreat from the little ice age lia advanced positions from 1890 to approximately 1950 followed by a period of advance from 1950 to 1976 and then retreat since 1976 2 rapid retreat from 1890 to approximately 1950 slow retreat or equilibrium from 1950 to 1976 and moderate to rapid retreat since 1976 3 continuous retreat from 1890 to the present type 1 glaciers are notable for steeper slopes extensive crevassing and higher terminus region velocities type 2 glaciers have intermediate velocities moderate crevassing and intermediate slopes type 3 glaciers have low slopes modest crevassing and low terminus region velocities this indicates that the observed differences in the response time and terminus behavior of north cascade glaciers in reaction to climate change are related to variations in specific characteristics of the glaciers the response time is approximately 20 30 years on type 1 glaciers 40 60 years on type 2 glaciers and a minimum of 60 100 years on type 3 glaciers the high correlation in annual balance between north cascade glaciers indicates that microclimates are not the key to differences in behavior instead it is the physical characteristics slope terminus velocity thickness and accumulation rate of the glacier that determine recent terminus behavior and response time the delay between the onset of a mass balance change and initiation of a noticeable change in terminus behavior has been observed on 21 glaciers to be 4 16 years this initial response time applies to both positive and negative changes in mass balance

time scale for adjustment of glaciers to changes in mass balance the length of time tm over which a glacier responds to a prior change in climate is investigated with reference to the linearized theory of kinematic waves and to results from numerical models we show the following tm may in general be estimated by a volume time scale describing the time required for a step change in mass balance to supply the volume difference between the initial and final steady states the factor f in the classical estimate of m l u where i is glacier length and u is terminus velocity has a simple geometrical interpretation ft is the ratio of thickness change averaged over the full length i to the change at the terminus although both u and f relate to dynamic processes local to the terminus zone the ratio f u and therefore tm are insensitive to details of the terminus dynamics in contrast to conclusions derived from some simplified kinematic wave models a more robust estimate of tm independent of terminus dynamics is given by tm h b where h is a thickness scale for the glacier and b is the mass balance rate negative at the terminus we suggest that tm for mountain glaciers can be substantially less than the 1o2 103 years commonly considered to be theoretically expected

electrical conductivity and streaming potential coefficient in a moderately alkaline lava series abstract coupled hydraulic and electrical problems are being investigated with renewed interest in geophysical applications in this study electrical conductivity and streaming potential coefficient spc have been measured in the laboratory for crushed oceanite hawaite and trachyte samples from an almost complete moderately alkaline lava series from the mururoa atoll french polynesia for ph varying from 7 to 9 5 and ionic strength varying from 0 1 to 100 mmol l despite the closely related mineralogy of the rocks contrasted results are obtained for the surface conductivity as defined by revil and glover 0 10 0 07 ms m 8 3 0 2 ms m and 1 05 0 16 ms m for oceanite hawaite and trachyte respectively and for the inferred potential 6 6 0 3 mv 26 3 0 5 mv and 14 6 0 3 mv respectively the higher values obtained with hawaite suggest that electrical properties are controlled by secondary and accessory minerals such as clay minerals and zeolites resulting from low temperature seawater alteration rather than by the magmatic differentiation furthermore a synthesis of results obtained with 20 rock samples indicates that signatures of the alteration process may emerge from the study of the potential as a function of surface conductivity the results with the lava series can be used to derive estimates of the scaling of basalt resistivity and associated spc as a function of permeability for permeability values smaller than 10 15 m 2 the value of the spc can be dramatically affected by the value of the surface conductivity at least in the brittle crust a better knowledge of the contributions of clay minerals and zeolites to surface conduction is therefore needed both for the interpretation of electrical conductivity profiles and for the estimation of electrical variations associated with groundwater flow as could be produced for example during volcanic or tectonic cycles

tectonics granitoids and mesozoic gold deposits in east shandong china abstract mesozoic granitoids in east shandong 1 contain some 30 moz gold making east shandong the largest granitoid hosted gold province in the world the gold province is located along the northern boundary of the suture zone between the north china and south china cratons according to their mineralogical geochemical and geochronological characteristics two groups of mesozoic granitoids are recognised in east shandong namely the middle yanshanian my ca 160 150 130 ma and the late yanshanian ly ca 117 85 ma granitoids the first group of granitoids only occur to the north of the suture zone whereas the second group of granitoids occur on both sides of the suture zone these characteristics suggest that the two groups of granitoids were associated with different tectonic events a tectonic analysis suggests that the my granitoids are the result of collision and suturing of the north and south china cratons during the triassic to jurassic whereas formation of the ly granitoids is attributed to the distal inland influence of subduction of the pacific izanagi plate underneath the eurasian continent during the cretaceous the major gold deposits are spatially associated with the my granitoids in east shandong most of the gold occurs either as quartz veins in the granitoids or disseminated in altered shear zones along the boundary of the granitoids and archaean metamorphic rocks the major gold mineralization and alteration generally display the characteristics of gold only provinces namely co 2 rich low salinity and reduced fluids and proximal mica and sulfide alteration these characteristics are different from those of phanerozoic granitoid related skarn porphyry systems accordingly the gold mineralization may be more tectonically and structurally controlled rather than have a direct genetic relationship with the granitoid itself according to the relationships between tectonics granitoids distribution of gold deposits and fluid geochemistry the major gold in east shandong may have been formed during the subsequent exhumation stage after the collision of the north and south china cratons