magma storage and ascent at lipari island aeolian archipelago southern italy at 223 81 ka the role of crustal processes and tectonic influence fluid inclusion studies together with volcanological and petrochemical data allow reconstruction of the magma feeding system of basaltic andesitic to andesitic activity during the oldest and intermediate stages of development of lipari island 223 81 ka a major magma storage zone is active during the overall investigated time span at depths of 22 km close to the crust mantle moho transition at which mantle derived mafic magmas tend to accumulate due to neutral buoyancy conditions beneath central type volcanoes m mazzacaruso m s angelo m chirica costa d agosto a shallower magma reservoir is located within the upper crust at 5 5 3 5 km associated with a major lithological discontinuity for fissural type volcanoes timpone ospedale monterosa m chirica tectonic structures are suggested to influence further magma ascent and storage at mid crustal depths 14 km with no ponding at shallower levels partial crustal melting processes at the roofs of the deep magma reservoirs 17 km are invoked to explain the origin of cordierite bearing lavas beneath m s angelo and m chirica costa d agosto volcanoes which were active during the intermediate stages of development of lipari 105 81 ka the generation of felsic anatectic melts in the lower crust could have created density and rheologic barriers to impede the passage of mafic melts and promote their ponding with influence on the subsequent evolution of lipari volcano

strike slip faulting and nested block rotations structural evidence from the cordillera de domeyko northern chile abstract based on a structural analysis tectonic rotations around vertical axes have been found affecting the sedimentary sequence of the purilactis group from the cordillera de domeyko of northern chile the affected rocks form the northern part of a pre existing syncline that was offset by two sets of strike slip faults during the upper eocene incaic orogeny uplift and shortening in the hangingwall of two main bounding thrusts initiated the strike slip faults which divided the purilactis group into several fault blocks further contraction of the enclosed block faulted area led to domino style anticlockwise rotation of the central main blocks and the bounding block faults with rotations up to 40 additionally eastward displacement of these blocks was accompanied by local indentation of the adjacent smaller blocks to the east giving rise to opposite rotation directions the block rotations may have been accommodated by a decollement located in the mudstone and evaporite of the basal part of the sequence tonel formation based on a reconstruction of the initial rock distribution different fault models are discussed and a model resembling pure shear deformation is proposed to explain the initiation of strike slip faults the occurrence of block rotations and the distortion of the block faulted domain

low density co2 rich fluid inclusions from charnockites of southwestern madurai granulite block southern india implications on graphite mineralization abstract characterization of fluid inclusions in graphite bearing charnockites from the southwestern part of the madurai granulite block in southern india reveals a probable relation with the formation and break down of graphite during the high grade metamorphism the first generation monophase pure co 2 inclusions the composition of which is confirmed by laser raman spectroscopy recorded moderate density 0 77 0 87 g cc corresponding to low tapping pressure around 2 kb than that of the peak granulite facies metamorphism the precipitation of graphite as inferred from graphite inclusions and 13 c values of the graphite from the outcrops is interpreted as the cause of this lowering of fluid density an intermediate generation of pseudosecondary inclusions resulted from the re equilibration or modification of the first generation fluids and the co 2 formed is interpreted to be the oxidation product from graphite the youngest generation of fluids which caused widespread retrogression of the granulites is a low temperature 350 c high saline 32 4 52 0 wt nacl equivalent brine carbon isotope data on the graphite from the charnockites show 13 c values ranging from 11 3 to 19 9 suggesting a possibility of mixing of carbon sources relating to earlier biogenic and later co 2 fluid influx combining the information gathered from petrologic fluid inclusion and carbon stable isotope data we model the fluid evolution in the massive charnockites of the southwestern madurai granulite block

the nature of mineralizing fluids of the kipushi zn cu deposit katanga democratic repubic of congo quantitative fluid inclusion analysis using laser ablation icp ms and bulk crush leach methods fluid inclusions from the epigenetic zn cu deposit of kipushi central african copper belt katanga democratic republic of congo have been subjected to an integrated microthermometric bulk crush leach and laser ablation inductively coupled plasma mass spectrometric la icp ms study to elucidate the physicochemical conditions of ore formation and the origin of the mineralizing fluids the kipushi deposit is hosted in carbonates and partly in siliciclastic rocks that have undergone regional low grade greenschist facies metamorphism and which were strongly deformed during the lufilian orogeny main deformation phase 550 ma investigation of host rock gangue and ore samples enabled reconstruction of the paragenesis of ore deposition the main zn cu ge pb sulfide mineralization was accompanied by three generations of hydrothermal dolomite and a generation of coarse grained quartz primary and pseudosecondary fluid inclusions in these minerals contain predominantly halite saturated aqueous brines 30 43 wt nacl equiv with locally unidentified trapped solids these inclusions mostly decrepitate upon heating before total homogenization which could suggest that they also trapped excess carbonic vapor they show petrographic and microthermometric evidence for postentrapment reequilibration prohibiting their use as accurate geothermometers and geobarometers previous studies on chlorite and sphalerite geothermometry framed the formation temperature of the kipushi cu zn deposit between 290 to 380 c younger fluids are present as secondary inclusions in the gangue minerals and as primary fluid inclusions in sphalerite from a minor secondary mineralization phase these two phase aqueous inclusions have a slightly lower salinity 23 31 wt nacl equiv and have homogenization temperatures ranging from 170 to 80 c in successive fluid inclusion assemblages sporadically some mixed aqueous carbonic and gaseous co2 ch4 inclusions are present but their genetic position is un clear and they are insignificant with regard to the mineralization process as a whole crush leach bulk analysis of the fluid inclusions show that the mineralizing fluids had a molar cl br ratio close to or somewhat higher than the seawater value which rules out a major contribution from bittern brines and suggests that the fluids gained their salinity primarily by the dissolution of evaporites younger fluids that circulated through the deposit after the main phase of ore formation have cl br and na br signatures indicative of a greater involvement of halite dissolution brines values much higher than that of seawater la icp ms analyses of the mineralizing fluids reveal that they have molar li na ca na mg na mn na and sr na in the range of natural high salinity fluids in metamorphic environments worldwide however they have relatively high molar fe na zn na pb na and especially very high ba na ratios their molar k na is also somewhat higher than for other low grade metamorphic fluids but is nevertheless in agreement with the values predicted by the k na geothermometer at the conditions of ore formation this suggests that the major element composition of the fluids was buffered by fluid mineral equilibria their relatively high metal contents ba zn fe and pb suggest that they interacted with and leached these elements from felsic basement rocks at higher temperatures whatever the origin of the fluids their salinity and the metals their uniformly high ba and ore metal content together with the absence of barite and the occurrence of ba silicates at kipushi indicates that sulfide mineralization occurred when the metal bearing fluids encountered a reducing h2s rich reservoir the ubiquitous presence of preexisting metamorphosed carbonic material shungite in the sulfides and host rock and a sulfur isotope signature of the ores in agreement with thermogenic sulfate reduction suggests that this condition was likely created due to the high initial reduced carbon content of the host rocks at kipushi which seems to be exceptional in the copper belt therefore we postulate that a critical factor in the formation of major vein type zn cu mineralization was the presence of a hydrocarbon rich facies of the lower nguba carbonates at kipushi

surface rupture during the 2010 mw 7 1 darfield canterbury earthquake implications for fault rupture dynamics and seismic hazard analysis the september 2010 m w 7 1 darfield canterbury earthquake in new zealand is one of the best recorded earthquakes of this magnitude the earthquake occurred on a previously unidentified fault system and generated a 29 5 0 5 km long surface rupture across a low relief agricultural landscape high accuracy measurements of coseismic displacements were obtained at over 100 localities along the greendale fault maximum net displacement d max 5 3 0 5 m and average net displacement d avg 2 5 0 1 m are anomalously large for an earthquake of this m w d max surface rupture length srl and d avg srl ratios are among the largest ever recorded for a continental strike slip earthquake geologically derived estimates of moment magnitude m w g are less than the seismologically derived m w derived using widely employed srl m w scaling regressions m w g is greater than m w using d max and d avg m w regressions the geologically derived static stress drop of 13 9 3 7 mpa provides a context with which to compare this earthquake rupture to interplate and intraplate ruptures of similar m w this data set provides fundamental information on fault rupture processes relevant to seismic hazard modeling in this region and analogous settings globally

physicochemical evolution of a porphyry breccia system a laser ablation icp ms study of fluid inclusions in the mount leyshon au deposit queensland australia the evolution of magmatism brecciation alteration and mineralization is described for the mount leyshon intrusive complex queensland australia using p t v x analysis and major to trace element analysis of single fluid inclusions using laser ablation icp ms the 290 ma mount leyshon intrusive complex is a subvolcanic porphyry breccia system mined for 97 metric tons t au 70 mt at 1 4 g t au between 1986 and 2000 the mount leyshon intrusive complex is characterized by several generations of genetically related breccias and magmatic intrusions both alteration and mineralization can be traced to specific intrusive events the earliest phase of brecciation was followed by widespread biotite magnetite alteration stage 1 fluid inclusions associated with stage 1 were trapped at 350 c and 145 bars and were anomalously k and fe rich this stage was followed by the emplacement of rhyolite to dacite stocks and coeval breccia pipes stage 2 fluids exsolved from these magmas simultaneously exsolved na k fe mn rich brine 60 wt nacl equiv and dilute vapor at 500 bars 2 km paleodepth and 600 c pressures likely oscillated between lithostatic and sublithostatic conditions in response to the transient rupture and sealing of intrusions and wall rocks hydrothermal fluids infiltrating breccia pore space produced base metal mineralization stage 3 stage 3 fluid inclusions contain 2 to 10 wt percent nacl equiv and were trapped at 300 to 400 c below 500 bars stage 3 fluids were depleted in k fe and mn and enriched in ca sr and ba relative to stage 2 brines this trend is consistent with the transition from potassic alteration in stage 2 to feldspar destructive phyllic alteration in stage 3 cu zn and pb were conservative elements above 350 c and precipitated nonselectively as sulfides below 350 c in a bulk ratio very similar to that measured in fluid inclusions subsequent emplacement of andesite to rhyodacite dikes stage 4 was marked by au and additional base metal sulfide mineralization in veins and breccia cavities stage 4 fluids are chemically similar to stage 3 but contain several mol percent co2 perhaps suggesting a more mafic co2 charged magma source relative to earlier intrusive pulses in addition to fluid cooling the destabilization of au bisulfide complexes attending phase separation of h2o co2 nacl fluids below 400 c and 400 bars was the likely cause for au precipitation mount leyshon appears to indicate that co2 can play a crucial role in the transport of gold bearing solutions from a magmatic source at depth into much shallower hydrothermal environments

silver base metal epithermal vein and listwanite hosted deposit crnac rogozna mts kosovo part ii a link between magmatic rocks and epithermal mineralization abstract crnac is an intermediate sulfidation pb zn ag epithermal deposit located within the vardar suture zone of the central balkan peninsula the epithermal pb zn ag mineralization consists of i a series of steeply dipping veins hosted within the jurassic amphibolites and ii overlying hydrothermal explosive breccia with angular level iv or rounded fragments of listwanite surface cemented by epithermal mineralization the mineralization is related to the oligocene quartz latite dykes that crosscut the crnac antiform quartz latite rocks predominantly display a shoshonitic character the obtained 40ar 39ar age of fresh quartz latite is 28 9 0 3 ma fine grained sericite from altered quartz latite is dated at 28 6 0 5 ma early alteration related fluid inclusions within quartz latite show coexistence of high density brine and a low density vapor saturated phase that homogenized at 280 405 c phase separation occurs at a paleodepth of 0 6 to 0 9 km epithermal mineralization developed in three stages i early pyrite arsenopyrite pyrrhotite quartz kaolinite ii main sphalerite galena tetrahedrite chalcopyrite and iii late carbonate pyrite arsenopyrite assemblage the onset of mineral deposition within epithermal veins was initiated by boiling of na cl k ca mg fluid at a paleodepth of 0 6 to 0 9 km coexisting vapor and liquid rich inclusions display salinities and trapping temperatures of 4 wt nacl equiv 280 370 c and 2 27 wt nacl equiv 230 375 c respectively boiling continued throughout the deposition of the sphalerite galena tetrahedrite chalcopyrite assemblage late stage carbonate was deposited from diluted non boiling low temperature na ca mg cl co2 fluid 0 2 to 4 8 wt nacl equiv 115 280 c about 100 150 m higher in the system precipitation of listwanite breccia cement began as a result of boiling na cl ca mg k fluid of medium salinities 2 6 to 12 1 wt nacl equiv at temperatures of 245 370 c boiling and dilution of fluids continue throughout the precipitation of the main sphalerite galena tetrahedrite and late mainly carbonate assemblage surface listwanite breccia contain quartz phenocrysts deposited from a homogeneous fluid with a medium salinity 8 10 wt nacl equiv and high temperatures th 295 315 c whereas the early and main stage of a surface listwanite breccia cement precipitated from a boiling fluid of decreasing salinity and temperature aqueous co2 high salinity 16 to 18 wt nacl equiv low temperature 120 c homogeneously trapped fluid that precipitated late stage carbonates is most likely a remnant of boiled off fluid the epithermal assemblage of the surface listwanites precipitated at a paleodepth of 0 4 to 0 6 km the 13c values of the late stage ankerite range from 4 2 to 4 1 whereas 18o range from 9 6 to 17 5 the calculated 18o of fluid that precipitated carbonates within epithermal veins and listwanite breccia cement range from 6 3 to 11 3 indicating a contribution of magmatic water deposition of all mineralization types was initiated by neutralization of primary acidic magmatic fluid by water rock reactions that caused widespread propylitization and sericitization extensive and long lasting boiling combined with dilution by meteoric water increased the ph towards the final stage of hydrothermal activity

response of the benthic nepheloid layer to near inertial internal waves in southern lake michigan 1 time series measurements of water transparency water temperature and current velocity were made at a station located in 58 m of water in southern lake michigan during the summer of 1995 currents generated by near inertial internal waves are correlated with variations in the thickness and in the vertical distribution of suspended sediment in the benthic nepheloid layer although a direct causal link between internal wave action and changes in the nepheloid layer could not be established the data suggest that local resuspension by shoaling internal waves maintains the layer during the stratified period the origin and maintenance of the benthic nepheloid layer is most likely the result of local resuspension due to a combination of internal wave action and longer term processes

package fluids 1 computer programs for analysis of fluid inclusion data and for modelling bulk fluid properties the computer package fluids contains five sets of computer programs written in c for the calculation of fluid properties both model fluids and data from fluid inclusions can be analysed in the programs bulk density molar volume and composition of fluid inclusions are calculated with the program bulk which uses microthermometric data micro raman spectroscopic data cation ratios and volume fraction estimations as input the program offers a broad variety of equations of state which are selected according to the fluid system or the temperature and pressure conditions of interest the isochores that correspond to the output or test v x properties of fluid inclusions are calculated by the program isoc in calculating the isochores this program takes account of the compressibility and expansion of selected host minerals the program test allows different equations of state to be compared directly with experimental data thereby facilitating selection of the most adequate model in the programs bulk and isoc loner is a group of programs that handle individual equations of state eos for all fluid systems presented in the programs bulk and isoc aqso is a group of programs that allows purely empirical modelling of electrolyte bearing aqueous solutions henry s law for dilute gas bearing aqueous solutions and osmotic coefficients for dilute electrolyte bearing aqueous solutions the programs are available on the university of leoben web site at http www unileoben ac at buero62 minpet ronald

three dimensional modeling of pull apart basins implications for the tectonics of the dead sea basin we model the three dimensional 3 d crustal deformation in a deep pull apart basin as a result of relative plate motion along a transform system and compare the results to the tectonics of the dead sea basin the brittle upper crust is modeled by a boundary element technique as an elastic block broken by two en echelon semi infinite vertical faults the deformation is caused by a horizontal displacement that is imposed everywhere at the bottom of the block except in a stress free shear zone in the vicinity of the fault zone the bottom displacement represents the regional relative plate motion results show that the basin deformation depends critically on the width of the shear zone and on the amount of overlap between basin bounding faults as the width of the shear zone increases the depth of the basin decreases the rotation around a vertical axis near the fault tips decreases and the basin shape the distribution of subsidence normalized by the maximum subsidence becomes broader in contrast two dimensional plane stress modeling predicts a basin shape that is independent of the width of the shear zone our models also predict full graben profiles within the overlapped region between bounding faults and half graben shapes elsewhere increasing overlap also decreases uplift near the fault tips and rotation of blocks within the basin we suggest that the observed structure of the dead sea basin can be described by a 3 d model having a large overlap more than 30 km that probably increased as the basin evolved as a result of a stable shear motion that was distributed laterally over 20 to 40 km

a comparison of observed and modeled surface waves in southern lake michigan and the implications for models of sediment resuspension 1 subsurface pressure sensors were used to make measurements of surface waves during 18 deployments in southern lake michigan between 1998 and 2000 most of the observations were made during the unstratified period november may in water depths between 10 and 55 m the observations as well as those obtained from the national data buoy center ndbc buoy 45007 which is located in the middle of the southern basin of the lake were compared to the results obtained from the great lakes environmental research laboratory glerl donelan wave model implemented on a 2 km grid the results show that the wave model does a good job of calculating the wave heights but consistently underestimates the wave periods in over 80 of the cases the bottom stresses calculated from both the observations and the wave model results agree as to whether or not resuspension occurs but over 70 of this agreement is for cases when resuspension does not occur both stresses predict resuspension about 6 of the time since the bottom stresses calculated from the model results are usually lower than those calculated from the observations resuspension estimates based on the wave model parameters are also lower than those calculated from the observed waves

geochemical and geochronological constraints on the formation of shear zone hosted cu au bi te mineralization in the stanos area chalkidiki northern greece abstract copper gold bismuth tellurium mineralization in the stanos area chalkidiki peninsula greece occurs in the proterozoic to silurian aged serbomacedonian massif which tectonically borders the mesozoic circum rhodope metamorphic belt to the west and crystalline rocks of the rhodope massif to the east this area contains the paliomylos chalkoma and karambogia prospects which are spatially related to regional nw se trending shear zones and hosted by marble amphibolite gneiss metagabbro and various muscovite biotite chlorite actinolite feldspar quartz schists of the silurian vertiskos unit metallic minerals occur as disseminated to massive aggregates along foliation planes and in boudinaged quartz veins iron bearing sulfides pyrite arsenopyrite and pyrrhotite formed prior to a copper bearing stage that contains chalcopyrite along with galena sphalerite molybdenite and various minerals in the system bi cu pb au ag te fluid inclusion homogenization temperatures of primary aqueous liquid vapor inclusions in stage i quartz veins range from 170 1 c to 349 6 c peak at 230 c with salinities of 4 5 to 13 1 wt nacl equiv calculated isochores intersect p t conditions associated with the upper greenschist facies caused by local overpressures during late stage tectonic movement along the shear zone in the eocene which produced stretching and unroofing of rocks in the region values of 34 s for sulfides in the stanos shear zone range from 2 42 to 10 19 and suggest a magmatic sulfur source with a partially reduced seawater contribution for fluids in equilibrium with quartz 18 o at 480 c varies from 5 76 to 9 21 but does not allow for a distinction between a metamorphic and a magmatic fluid a 187 re 187 os isochron of 19 2 2 1 ma for pyrite in the paliomylos prospect overlaps ages obtained previously from intrusive rocks spatially related to the skouries porphyry cu au the asimotrypes au and the intrusion related palea kavala bi te pb sb au deposits in northern greece as well as alteration minerals in the carbonate replacement madem lakkos pb zn deposit ore forming components of deposits in the stanos area were likely derived from magmatic rocks at shallow depth that intruded an extensional shear environment at 19 ma

block rotation by basement strike slip faulting in the sanchu graben central japan abstract in the kanto mountains central japan cretaceous fore arc basin sediments are sandwiched by basement rocks in a narrow zone traditionally called the sanchu graben in the axial part of the graben they are divided into numerous blocks by a series of subparallel sinistral strike slip oblique faults block faults these blocks have rotated clockwise together with block faults resulting clockwise deviation of strike of the strata from the general trend increases gradually from the margins toward the axial part of the graben where it attains 30 block faults are traced in part of the graben where the strata show this clockwise deviation of strike the structural evidence and the high length width ratio of the rotated domain suggest that a major dextral strike slip fault lies beneath the cretaceous cover of the axial part the unconformable boundary between the cretaceous cover and the underlying basement may have played the role of a detachment plane and prevented the fault from extending into the cover the rotation of the overlying cretaceous system is thus a superficial manifestation of underlying dextral strike slip faulting

sediment resuspension and transport in lake michigan during the unstratified period instrumented moorings were deployed during the winter of 1994 95 at three depths 28 58 and 101 m in southern lake michigan storms during the observation period were not unusually severe so the processes observed are typical of those that occur during an average winter time series observations of water temperature beam attenuation coefficient a measure of water transparency and current velocity show that local resuspension of bottom sediment occurred frequently after the breakdown of the thermocline resuspension was most frequent close to the shore but was also observed at the 58 m station local resuspension did not occur at the 101 m station but advection to the site of material resuspended at shallower sites was observed these observations do not support the hypothesis proposed by previous investigators that local resuspension at depths of 100 m or greater occurs during the unstratified period it is more likely that fine grained material resuspended by storm action in intermediate water depths 30 60 m is transported into the deeper parts of the lake by the general lake circulation

sedimentary processes in the great lakes sediments in the great lakes are subject to four general categories of processes input transport deposition and postdepositional alteration sedimentary input is from coastal erosion 64 riverine input 26 atmospheric transport 3 and several lesser sources 7 once in the lake sediments are transported to their place of deposition along the bottom and or in suspension depending upon grain size and density the rate of deposition in the great lakes is variable and ranges from zero in some areas to over 6000 g m sup 2 yr sup 1 in the eastern basin of lake erie after deposition sediments undergo bioturbation dissolution of carbonate and opal remobilization of many metals followed by reprecipitation within the surficial oxidized layer and degradation of organic compounds

the role of magmatic and hydrothermal processes in the evolution of be bearing pegmatites evidence from beryl and its breakdown products beryl and euclase crystals from the mina do santino and the jacu pegmatites in the borborema pegmatite province in northeastern brazil contain several generations of melt and fluid inclusions which allow interpretation of p t x conditions responsible for beryl crystallization and for alteration of a primary pegmatitic mineral assemblage to a mixture of hydrothermal minerals euclase bertrandite kaolinite and quartz primary melt and fluid inclusions hosted by beryl were trapped simultaneously however their homogenization temperatures are significantly higher 870 900 c than the values previously reported for pegmatitic systems 712 c and should be treated with caution an isobaric drop of temperature resulted in the exsolution of a fluid a low salinity co2 enriched phase and a saline water rich phase were trapped in pseudosecondary inclusions in beryl at a pressure of 2 1 2 7 kbar and temperature of 390 480 c cooling of the country rocks below 400 c caused a ductile to brittle transition and allowed infiltration of cold groundwater which further decreased the temperature in the system to 190 240 c at the same time the pressure dropped from a lithostatic 2 1 2 7 kbar to a hydrostatic value 0 57 0 73 kbar consequently minerals deposited under magmatic conditions feldspars and beryl became unstable and a newly formed hydrothermal mineral paragenesis euclase bertrandite kaolinite and quartz overprinted the earlier one the hydrothermal fluids responsible for the alteration differ from the earlier exsolved fluids in having a lower salinity lower homogenization temperature the absence of co2 and the presence of ch4

kinematic analysis of rotated fractures and blocks in simple shear deformation in part of the surface rupture of the imperial valley california earthquake of 15 october 1979 provides a geometric and mechanical analog for the model of tectonic evolution of southern california in miocene time as proposed by luyendyk et al 1980 the n35w striking fault broke as an irregular series of left stepping en echelon r shears across a field that prior to the earthquake had been scored by n s oriented furrows between overlapping segments of the r shears elongate blocks of soil separated along the furrows and rotated up to 70 clockwise the furrows functioned as planar discontinuities which guided and accommodated shear strain in those parts of the mole track between the r shears the relatively rigid blocks detached on an irregular horizontal decollement from the less rigid subsoil triangular gaps opened between blocks where rotation was variable blocks buckled or were thrust out of the shear zone where they were constrained by the walls of the shear zone the geometry and kinematics of structures in the mole track virtually duplicate the larger scale structures and requisite movements in the regional tectonic model and show that the regional model is plausible

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

seismic evidence for conjugate slip and block rotation within the san andreas fault system southern california the pattern of seismicity in southern california indicates that much of the activity is presently occurring on secondary structures several of which are oriented nearly orthogonal to the strikes of the major through going faults slip along these secondary transverse features is predominantly left lateral and is consistent with the reactivation of conjugate faults by the current regional stress field near the intersection of the san jacinto and san andreas faults however these active left lateral faults appear to define a set of small crustal blocks which in conjunction with both normal and reverse faulting earthquakes suggests contemporary clockwise rotation as a result of regional right lateral shear other left lateral faults representing additional rotating block systems are identified in adjacent areas from geologic and seismologic data many of these structures predate the modern san andreas system and may control the pattern of strain accumulation in southern california geodetic and paleomagnetic evidence confirm that block rotation by strike slip faulting is nearly ubiquitous particularly in areas where shear is distributed and that it accommodates both short term elastic and long term nonelastic strain a rotating block model accounts for a number of structural styles characteristic of strike slip deformation in california including variable slip rates and alternating transtensional and transpressional features observed along strike of major wrench faults domains of evenly spaced antithetic faults that terminate against major fault boundaries continued development of bends in faults with large lateral displacements anomalous focal mechanisms and differential uplift in areas otherwise expected to experience extension and subsidence since block rotation requires a detachment surface at depth to permit rotational movement low angle structures like detachments of either local or regional extent may be involved in the contemporary strike slip deformation of southern california a block nature of the crust also implies that not only will strains be inhomogeneous and likely concentrated along edge bounding faults but that local stress orientations will largely be responding to local kinematic constraints of block rotation and fault interaction this behavior coupled with the presence of possible regional detachments accounts for some of the precursory changes observed at considerable distances prior to large earthquakes and the triggering of seismicity or slip on nearby faults or around adjacent block edges although fault displacements along secondary structures associated with block rotations remain small they may still influence the nucleation and the characteristic rupture length of large earthquakes a more complete description of what these structures are and how they interact may prove critical to any fundamental understanding of the earthquake process and any realistic assessment of the regional seismic hazard

formation of a giant zn pb deposit from hot brines injecting into a shallow oil gas reservoir in sandstones jinding southwestern china the association between mineralization and hydrocarbons in sedimentary basins is widely recognized but the nature and significance of their relationships are not fully understood this paper provides an example of metalliferous brines injecting into a palaeo oil gas reservoir to form a world class zn pb deposit jinding china petrographic and microthermometric studies of oil inclusions and pvt simulations suggest that oil and gas were charged in a shallow 1300 m environment before mineralization this environment favoured bacterial sulfate reduction bsr which produced large amounts of h2s that accumulated in the gas cap forceful injection of hot brines penetrated the oil zone to reach the h2s rich gas cap and precipitated sulfide ores individual fluid injection events were short lived and the reservoir was only partly and briefly heated to beyond the bacterial survival temperature episodic injection of metalliferous brines and sustained supply of h2s through bsr resulted in the formation of a large zn pb deposit this article is protected by copyright all rights reserved

overprinted strike slip deformation in the southern valley and ridge in pennsylvania abstract two major faults over 32 km long and 6 4 km apart truncate or overprint most previous folds and faults as they trend more northerly than the previous n25 e to n40 e fold trends the faults were imposed as the last event in a region undergoing sequential counter clockwise generation of tectonic structures the western big cove anticline has an early nw verging thrust fault that emplaces resistant rocks on its nw limb a 16 km overprint by the cove fault is manifested as 30 small northeast striking right lateral strike slip faults this suggests major left lateral strike slip separation on the cove fault but steep dip slip separation also occurs from south to north the cove fault passes from se dipping beds within the big cove anticline to the vertical beds of the nw limb then it crosses four extended separated tuscarora blocks along the ridge brings cambro ordovician carbonates against devonian beds and initiates the zone of overprinted right lateral faults finally it deflects the lat 40 n fault zone as it crosses to the next major anticline to the northwest to the east the major path valley fault rotates and overprints the earlier carrick valley thrust the path valley fault and cove fault may be mesozoic in age based upon fault fabrics and overprinting on the east west lat 40 n faults

vertical and horizontal particle transport in the coastal waters of a large lake an assessment by sediment trap and thorium 234 measurements 1 the horizontal and vertical flux of particulate material in the nearshore of southern lake michigan 0 40 m was estimated with the naturally occurring radionuclide 234th horizontal fluxes of 234th supplemented apparent vertical fluxes of 234th in the water column based on local 234th 238u disequilibria by a factor of 7 14 reinforcing the importance of lateral transport in coastal environments calculated onshore transport of particulate material across the 40 m isobath was as high as 1 1 106 kg km 1 d 1 and exceeds estimates of terrigenous riverine and bluff erosion loading estimates of onshore flux of organic carbon exceeded areal primary productivity by as much as 300 and should be considered in nearshore carbon budgets bottom tethered sediment traps placed 5 m above the bottom measured sedimentation rates that were 1 order of magnitude lower than 234th derived mass fluxes from the water column and 2 orders of magnitude lower than 234th derived mass fluxes to the lakebed we ascribe this difference to under collecting by the sediment trap either because of trap hydrodynamics or flux occurring below the trap capture plane cross shore fluxes showed a periodicity of 4 days and correlated strongly with a topographic vorticity wave that is present throughout the year in southern lake michigan the impact of this wave as a driver of bidirectional cross shore flux on biogeochemical cycling and both nearshore and offshore food webs has not yet been explicitly considered

geology mineralization and fluid inclusion characteristics of the lermontovskoe reduced type tungsten cu au bi skarn deposit sikhote alin russia abstract the lermontovskoe deposit 48 kt wo 3 average 2 6 wo 3 0 24 cu 0 23 g t au is situated in a w sn au metallogenic belt that formed in a collisional tectonic environment this tungsten skarn deposit has a w au as bi te sb signature that suggests an affinity with reduced intrusion related au deposits the deposit is associated with an intrusion that is part of the ilmenite series high k peraluminous granitoid granodiorite to granite suite these rocks formed via mantle magma induced melting of crustal sources the deposit comprises reduced type pyroxene dominated prograde and retrograde skarns followed by hydrosilicate amphibole chlorite pyrrhotite scheelite quartz and phyllic muscovite sericite carbonate albite quartz scheelite sulfide with abundant apatite alteration assemblages fluid inclusions from the skarn assemblages indicate high temperature 500 c high pressure 1400 1500 bars and high salinity 53 60 wt nacl equiv magmatic hydrothermal fluids they were post dated by high carbonic methane dominate low salinity fluid at the hydrosilicate alteration stage these fluids boiled at 360 380 c and 1300 1400 bars the subsequent phyllic alteration started again with a high temperature 450 c high pressure 1000 1100 bars and high salinity 42 47 wt nacl equiv fluid with further incursion of high carbonic methane dominated low salinity fluid that boiled at 390 420 c and 1150 1200 bars the latest phyllic alteration included the lower temperature 340 360 c lower pressure 370 400 bars high carbonic methane dominated but with higher co 2 fraction low salinity fluid and then the low temperature 250 300 c h 2 o co 2 ch 4 nacl fluid with both fluids boiled at the deposit level the high salinity aqueous fluids are interpreted to have come from crystallizing granitoid magma whereas the reduced high carbonic fluids probably came from a deeper mafic magma source both of these fluids potentially contributed to the w au as bi te sb metal budget decreasing temperatures coupled with high aca 2 and fluid boiling promoted scheelite deposition at all post skarn hydrothermal stages the deposit is characterized by limited downdip extent of mineralized zones and abundant coarse grained muscovite quartz apatite scheelite aggregates that formed at the phyllic alteration stage together with presence of high temperature high pressure and high salinity fluids directly exsolving from crystallizing magma this suggests a root level of the mineralized magmatic hydrothermal system of reduced w skarn deposits

tracing fluid saturation during pegmatite differentiation by studying the fluid inclusion evolution and multiphase cassiterite mineralisation of the gatumba pegmatite dyke system nw rwanda abstract aqueous fluid saturation during the internal evolution of phosphorus and boron rich pegmatites in nw rwanda has been investigated using petrography fluid inclusion microthermometry and microanalysis of minerals and fluid inclusions raman microspectroscopy and la icp ms the gatumba dyke system gds in rwanda has been selected for this study because it hosts a multiphase cassiterite mineralisation in wall core and internal replacement zones suggesting an advancing influence of magmatic hydrothermal conditions during dyke solidification as such multiphase cassiterite precipitation is applied as a tracer for magmatic to hydrothermal crystallisation processes in granitic pegmatites the gds consists of a group of six major lct lithium caesium tantalum family dykes which all belong to the most differentiated rare element pegmatites in the gatumba gitarama field petrography identified a well developed internal anatomy consisting of a border wall intermediate and a quartz core zone in addition replacement zones developed as cleavelandite after perthitic microcline units in the intermediate zone and as muscovite quartz pockets in the intermediate and wall zones the latter replacement zone display muscovitisation reactions with the formation of greisens texturally the greisen pockets replace the secondary cleavelandite units during internal differentiation multiphase cassiterite mineralisation formed in 1 large microcline crystals of the wall zone cst1 2 assemblage with quartz f poor montebrasite and carbonate and boron enriched mn fluorapatite in the core zone cst2 and 3 the greisen replacement units in the wall and intermediate zones cst3 fluid inclusion micro analyses demonstrate that a saline aqueous h2o nacl kcl co2 n2 l1 type fluid 20 wt nacl and 3 wt kcl was saturated during onset of crystallisation of the wall and intermediate zones and precipitation of the disseminated magmatic hydrothermal cst1 mineralisation in and around large perthitic k feldspars isochore reconstructions of this l1 fluid indicate crystallisation conditions of 535 560 c and 5 1 5 6 kbar for the gds extensive microcline fractionation and subsequent replacement reactions of cleavelandite after microcline in the intermediate zone were induced by a li enriched and more na depleted h2o nacl licl co2 n2 l2 type fluid which was present during solidification of the core zone and present during precipitation of cst2 phase mineralisation 6 12 wt nacl 1 10 wt licl late stage hydrothermal cst3 mineralisation in the greisen pockets precipitated from a cs enriched h2o nacl kcl co2 n2 l3 type fluid 15 wt nacl distinctly after the formation of the cleavelandite replacement units subsolidus cst3 precipitation is dominantly driven by metasomatic hydrolytic fluid rock reactions combining textural microthermometric and fluid compositional data with reported sn melt fluid partitioning and solubility data demonstrate that primary cassiterite i e cst1 and cst2 in the wall and core zone of the gds precipitated from the exsolved saline aqueous l1 and l2 fluid present at the interface of the highly fractionated melt phase fast disequilibrium growth of near anhydrous mineral assemblages likely caused the formation of flux rich and at least locally water saturated melt compositions at the crystallisation front of the large crystals this study emphasises the importance of local magmatic hydrothermal conditions and the presence of an immiscible aqueous fluid phase during the internal crystallisation and cassiterite mineralisation of rare element pegmatites

neotectonic intersection of the aegean and cyprus tectonic arcs extensional and strike slip faulting in the isparta angle sw turkey abstract the isparta angle and adjacent antalya bay areas constitute an important segment of the eastern mediterranean region located at the intersection of the southward convex aegean and cyprus arcs some recent tectonic maps show the isparta angle as a nw se compressional lineament extending eastwards into the kyrenia range of northern cyprus however fault data from the onshore isparta angle together with offshore shallow seismic reflection data show that the present morpho tectonic setting is dominated by extension the last phase of compression to affect the area studied in the late miocene was accompanied by regional nappe emplacement lycian nappes onshore fault planes measured from fault zones bounding both the limbs and the core of the isparta angle are oriented predominantly ne sw nw se and n s superimposed slickenfibres show that reverse faults were succeeded in turn by right lateral faults then by normal faults the fault phases are dated by stratigraphical and geomorphological evidence reverse faults date from the late miocene or earlier compressional deformation whereas the right lateral faults mainly developed during latest miocene early pliocene normal faulting dominated from the late pliocene recent an interpretation of shallow seismic reflection data shows that antalya bay is characterised by a nw se trending asymmetrical graben system that has continued to be active during the late miocene early pliocene right lateral strike slip resulted from shear along the eastern termination of a zone of extension and rotation that characterises the western aegean this shear was focused in a n s direction by inherited zones of structural weakness in the basement antalya complex the switch to ne sw extension in the late pliocene quaternary relates to a regional change in stress direction throughout the aegean region and was accompanied by strong uplift of the bey da lari region of the taurus mountains bordering the isparta angle in the west the isparta angle is the link between a the extensional province of western turkey bounded to the south by the actively subducting hellenic arc and b the uplifted anatolian plateau bounded to the south by the cyprus subduction zone understanding the miocene to recent tectonic development helps elucidate the kinematics of the region the new structural data presented lend no support for recent suggestions that the isparta angle and antalya bay represent parts of a regional compressional zone related to plate collision

cretaceous sinistral strike slip along nacimiento fault in coastal california the san andreas and nacimiento faults of coastal california both separate granitic and metamorphic basement rocks of the salinian block from partly coeval but contrasting mesozoic terranes underlain by the franciscan subduction complex by analogy with neogene dextral strike slip along the san andreas fault cretaceous sinistral strike slip can be inferred along the nacimiento fault in preference to hypotheses for tectonic erosion during subduction or for dextral strike slip of unspecified amount following restoration of known san andreas and inferred proto san andreas dextral displacements reversal of about 560 km 350 mi of postulated sinistral slip on the nacimiento fault brings four major mesozoic lithotectonic belts of california and baja california into simple al gnment as subparallel terranes related to mesozoic subduction along the continental margin neogene deformation within the san andreas transform system involved a elongation of the salinian block by dextral slip along subsidiary faults that branch from the san andreas fault and b dextral rotation of crustal panels within the transverse ranges latest cretaceous and or earliest paleogene dextral slip along a proto san andreas fault followed the san andreas course in central california but diverged westward in southern california nacimiento sinistral displacements occurred in mid cretaceous to early or medial late cretaceous time after cretaceous emplacement of plutons now within the salinian block but prior to deposition of uppermost cretaceous sedimentary sequences in central california available data on mesozoic relative and absolute plate motions in the mesoameric n region support the likelihood of cretaceous sinistral strike slip subparallel to the california continental margin paleotectonic reconstruction of crustal blocks in california and baja california to their inferred mid cretaceous relative positions shows the salinian block inserted on a bias between the flanking mojave and peninsular ranges blocks salinian granitic rocks thus formed an interior part of the mesozoic batholith belt and their initial strontium isotopic ratios are compatible with the gradients displayed by values from the adjoining blocks the similar mesozoic terranes that now lie east and west of the salinian block were then adjacent to one another west of the sierra nevada block available paleomagnetic data neither support nor preclude the reconstruction but additional work together with future detailed lithotectonic comparisons potentially can confirm or refute the hypothesis i represents a correct interpretation of the nacimiento fault is important for understanding the overall tectonic framework of petroliferous basins both onshore and offshore in coastal california

an in situ erosion rate for a fine grained marine sediment near bottom current and particulate concentration data and a theoretical model of sediment resuspension together have led to inferences about the erosional response of a fine grained sediment to bottom stress tidal boundary layer observations made 5 m from the bottom in the main basin of puget sound washington show that currents with speeds exceeding 40 cm s cause an increase in concentration as much as sixfold from a background level of 1 mg 1 when the erosion rate e is given a power law dependence on bottom stress in accord with laboratory fine sediment entrainment measurements the field data and theoretical model together suggest that 4 0 and 1 7 10 6 g cm2 s uncertainty in these values stemming from a variety of factors is discussed the analysis also points to sediment resuspension of material with relatively large settling velocity ws 0 1 cm s taking place against a background of much finer particles and a depth of sediment reworking of approximately 0 3 mm under typical strong flow conditions comparison of this in situ erosion rate with previous laboratory rate estimates shows it to be comparable to rates measured for some freshwater sediments

atypical gold mineralization in an orogenic setting the bohaun deposit western irish caledonides the bohaun gold deposit in county galway western ireland is located in the caledonian orogenic belt proximal to a major accretionary boundary the mineralization is hosted in a normal extensional fault representing a zone of repeated extension and vein infilling of open cavities within clastic sedimentary rocks that have only reached the late diagenetic zone of low grade metamorphism the mineralization consists of undeformed veins stockworks and breccias quartz dominates all the veins and commonly shows multiple growth stages and a variety of classic epithermal textures including comb plumose and banded indicative of low confining pressures the veins have a simple mineralogy made up of quartz sericite chlorite with minor sulfides hematite rare visible gold with a high silver content up to 41 wt and late barite and dolomite vein quartz is associated with two fluids compositions type i with moderate to high salinity 8 0 23 6 wt nacl equiv and type ii with low to moderate salinity 0 0 7 8 wt nacl equiv co2 contents in both fluid types are 3 5 wt percent the majority of fluid inclusion homogenization temperatures range from 126 to 257 c and geologically constrained depth estimates 5 km indicate maximum fluid inclusion trapping temperatures between 175 and 245 c the geodynamic setting of bohaun which is located in a deformed continental margin of an allochthonous terrane is typical of orogenic gold deposits however an orogenic association for the bohaun mineralization is discounted on the basis of fluid inclusion evidence atypical vein textures gold grain composition and undeformed veins while vein textures locally resemble those found in epithermal quartz adularia mineralization there is no obvious magmatic association and alteration is restricted to the veins and immediate host rocks the origin of the gold at bohaun remains enigmatic however we favor an association with widespread carboniferous or later mineralizing fluids and a model which involves transport and deposition of gold from a basinal brine type fluid in a similar fashion to red bed au pd mineralization bohaun provides further evidence that low temperature brines may be capable of generating economic grade gold mineralization independent of other fluids

the vilalba gold district a new discovery in the variscan terranes of the nw of spain a geologic fluid inclusion and stable isotope study abstract this work defines the vilalba gold district a new gold region in the nw of spain comprising three mineralized areas castro de rei valina azumara and arcos and two different types of mineralization 1 w au skarn in castro de rei and 2 au as ag pb zn cu sb vein disseminated mineralization in valina azumara and arcos mineralization is mainly hosted by impure limestone and black slates lower cambrian and spatially related to variscan and late variscan structures rhyolite dikes occur in arcos 299 6 ma and castro de rei both consisting of peraluminous high potassium and calc alkaline rocks these dikes represent the fractionated expression of unexposed post tectonic granitoids located at depth the castro de rei area exhibits a contact aureole with biotite cordierite and calc silicate hornfels prograde skarn consists of garnet pyroxene quartz wollastonite and scheelite the retrograde alteration took place in two stages and mainly consists of amphibole epidote zoisite quartz calcite chlorite and sulfides gold mineralization in the skarn occurs as invisible gold in sulfoarsenides and as electrum related to bi te s minerals the mineralization of valina azumara and arcos comprises two stages the first consists of as rich pyrite and arsenopyrite with invisible gold the second stage mainly consists of base metal sulfides and ag pb zn cu sb sulfosalts hydrothermal fluids involved in the skarn formation are low salinity up to 6 6 wt nacl eq aqueous carbonic fluids h2o co2 ch4 n2 evolving into aqueous fluids during the last stage of gold mineralization stable isotope geochemistry indicates the importance of a magmatic fluid in the early stages 18osmow from 7 5 to 11 34scdt from 2 7 to 5 9 that evolved through interaction with host rocks and mixing with metamorphic and or meteoric fluids the 34scdt values 7 8 10 9 of second retrograde stage sulfides suggest the incorporation of 34s enriched from host rocks in valina azumara and arcos the fluid inclusion and isotope studies indicate similar hydrothermal fluids to those associated with the second retrograde skarn stage taking into account the fluid inclusion study and mineral geothermometry an attempt was made to determine the p t conditions of ore formation the prograde skarn of castro de rei formed at temperatures and pressures ranging from 520 to 560 c and from 1 7 to 2 5 kb the mineralization of valina azumara formed at minimum p t conditions of 1 7 kb and 355 c the estimated temperatures for the arcos mineralization are similar to those of valina azumara up to 383 c but at lower pressures we propose the model of intrusion related gold systems irgss to explain the mineralizations of the vilalba gold district in this model the castro de rei skarn and the valina azumara mineralization represent a proximal and a distal deposit respectively relative to an unexposed granitoid situated at depth we also consider arcos as a distal deposit in relation to another unexposed granitoid located further south in the district

post younger dryas seasonality in the north american midcontinent region as recorded in lake huron varved sediments a sediment core from northwestern lake huron contains a sequence of red and gray layered sediments that are postglacial and early holocene glaciolacustrine varves two hundred and sixty four couple

internal differentiation of the archean continental crust fluid controlled partial melting of granulites and ttg amphibolite associations in central finland fault bound blocks of granulite and enderbite occur within upper amphibolite facies migmatitic tonalitic trondhjemitic granodioritic ttg gneisses of the iisalmi block of central finland these units record reworking and partial melting of different levels of the archean crust during a major tectonothermal event at 2 6 2 7 ga anhydrous mineral assemblages and tonalitic melts in the granulites formed as a result of hydrous phase breakdown melting reactions involving amphibole at peak metamorphic conditions of 8 11 kbar and 750 900 c a nominally fluid absent melting regime in the granulites is supported by the presence of carbonic fluid inclusions the geochemical signature of light rare earth element lree depleted mafic granulites can be modelled by 10 30 wt partial melting of an amphibolite source rock leaving a garnet bearing residue the degree of melting in intermediate granulites is inferred to be less than 10 wt and was restricted by the availability of quartz pressure temperature estimates for the ttg gneisses are significantly lower than for the granulites at 660 770 c and 5 6 kbar based on the p t conditions melting of the ttg gneisses is inferred to have occurred at the wet solidus in the presence of an h 2 o rich fluid a hydrous mineralogy abundant aqueous fluid inclusions and the absence of carbonic inclusions in the gneisses are in accordance with a water fluxed melting regime low ree contents and strong positive eu anomalies in most leucosomes irrespective of the host rock composition suggest that the leucosomes are not melt compositions but represent plagioclase quartz assemblages that crystallized early from felsic melts furthermore similar plagioclase compositions in leucosomes and adjacent mesosomes are not a migmatite paradox as both record equilibration with the same melt phase percolating along grain boundaries

fluids at crustal pressures and temperatures the pressure volume temperature data of several gases h2 o2 co ch4 n2 and co2 have been used to obtain the following corresponding states equation p 1 kbar t 400 k z 0 0878 a bp r cp r 2 21 where z is the compressibility factor p r reduced pressure p critical p t r reduced temperature t critical t and the coefficients are given by a 1 0 5917 t r 2 b 0 09122 t r 1 c 1 4164 10 4t r 2 2 8349 10 6 ln t r p 1 kbar t 400 k at pressures below 1 kbar z is given by z 0 0761 1 bp r cp r 2 23 where b 0 09827 t r 1 0 2709 t r 3 c 0 01472 t r 4 0 00103 t r 1 5 for water p 1 kbar t 400 k z 0 0209 a bp cp2 22 where a 0 7025 1 16 10 3t 99 6799 t 1b 0 2143 t 1 3 1423 10 14t3c 2 249 10 6t 1 0 1459 t 3 2 1690 10 15t2 at pressure below 1 kbar the equation is p 100 bar t 673 k z 0 0601 1 b v c v2 24 where b 2 20960 t0 5 3 35460 10 8 t3c 3 4569 10 5t2 5 64 9764 ln t fugacities of the gases may be obtained by integrating the z equations separately and combining the results as follows int limits 1 p vdp rt text left int limits 1 1000 z 23 pdp int limits 1000 1 z 21 pdp right 26 the subscript in z denotes the equation which is to be used for calculating z

fluid evolution of indus basin ladakh north west himalaya india constraint from fluid inclusion and oxygen isotope thermometry fluid inclusions and oxygen isotope thermometry were carried out on quartz calcite veins of the indus basin in indus suture zone isz of northwest ladakh himalaya to constrain fluid evolution history of the basin three types of veins are identified as fault fill network and sigmoidal in the study area the fault fill veins microstructures of calcite and quartz suggest the deformation temperature of veins between 250 and 400 c and oxygen isotope thermometry provide the range between 192 and 359 c the network type veins microstructures of calcite revel deformation temperature in the range of 170 250 c and oxygen isotope thermometry indicate vein temperature range between 144 and 276 c stable isotopic values of sigmoidal and network type veins suggest the magmatic source of fluid the fault fill veins display magmatic to the marine fluid signature microstructures and isotope data set advocate the formation of veins from the wall rocks by leaching processes fluid inclusion microthermometric dataset indicates that veins were formed at a maximum depth of 20 km at 700 c the co2 fluids were trapped below 6 2 kbar at 700 c ch4 fluid was trapped at a shallower depth between 4 2 kbar 650 c and 2 3 kbar 381 c the primary aqueous fluids were trapped below 3 0 kbar up to 2 3 kbar at 594 to 382 c and secondary aqueous fluids were trapped between 2 9 and 1 5 kbar at 359 to 197 c the p t path for the entrapment defines an initial isothermal decompression itd itd is also supported by decrepitated and stretched inclusions texture as well as c shaped or hook like fluid inclusions morphology which collectively points towards fast basin uplift

the relative importance of wind and ship waves in the littoral zone of a large lake surface waves and their interactions with sediments and benthic organisms are the main hydrodynamic process affecting littoral ecosystems here we present a long term data set on surface wave parameters which was obtained from the analysis of measurements with a pressure sensor the data set covers a time period of a year and allows for resolving waves with heights down to less than a centimeter and frequencies up to 0 8 hz wind waves and three different types of ship waves were distinguished by their spectral properties in lake constance ship generated waves are as important as wind generated waves and contribute about 41 of the annual mean wave energy flux to shore in summer during the most productive time period ship waves dominate the wave field in terms of the energy flux to shore and also in their frequency of occurrence ship waves cause a diurnal and a seasonal pattern in the frequency of occurrence and in the heights of surface waves whereas in the case of wind waves these parameters do not vary significantly with season or between nighttime and daytime in contrast to wind waves that occur only sporadically ship waves propagate into the littoral zone very frequently at regular time intervals the different pattern of occurrence of ship and wind waves results in a different pattern of disturbance in the littoral ecosystem

bottom stress generation and sediment transport over the shelf and slope off of lake superior s keweenaw peninsula 1 data from near bottom instruments reveal that the mechanisms responsible for generating bottom stresses and resuspending sediment over the shelf and slope off of lake superior s keweenaw peninsula exhibit distinct seasonal variations notably near bottom flows over the slope are persistently weak 10 cm s 1 during summer but frequently attain high speeds in excess of 20 cm s 1 in autumn and winter during the intense storms of autumn and winter the generation of bottom stress is enhanced by the action of near bottom orbital velocities due to surface waves even at 90 m depth orbital velocities can increase bottom stress by a factor of up to 20 during storms where the seasonal thermocline intersects the lake floor bottom stress is also considerably enhanced often by more than a factor of 2 by high frequency motions in the internal wave band over the keweenaw slope sediment resuspension is largely confined to autumn and winter episodes of high bottom stress our analysis indicates that this resuspended material tends to be carried offshore a phenomenon that is partly due to the coincidence of the direction of the buoyancy driven component of the keweenaw current with downwelling favorable alongshore winds as a result of this coincidence currents and bottom stresses tend to be greater during periods of downwelling as opposed to upwelling circulation a potential challenge to modeling storm driven resuspension in the study region is indicated by observations that the minimum stress required for resuspension may vary significantly with time over the autumn and winter index terms 4558 oceanography physical sediment transport 4211 oceanography general benthic boundary layers 4239 oceanography general limnology keywords sediment transport sediment dynamics bottom boundary layer dynamics

the gounkoto au deposit west africa constraints on ore genesis and volatile sources from petrological fluid inclusion and stable isotope data the loulo gounkoto complex in the kedougou kenieba inlier hosts three multi million ounce orogenic gold deposits situated along the senegal mali shear zone this west malian gold belt represents the largest west african orogenic gold district outside ghana the gounkoto deposit is hosted to the south of the gara and yalea gold mines in the kofi series metasedimentary rocks the ore body is structurally controlled and is characterised by sodic and phyllic alteration as and fe rich ore assemblages with abundant magnetite and overall enrichment in fe as cu au ag w ni co ree minor te pb se cd fluid inclusion analysis indicates that the deposit formed at p t conditions of approximately 1 4 kbar and 340 c and that two end member fluids were involved in mineralisation 1 a moderate temperature 315 340 c low salinity 10 wt nacl equiv low density 1 g cm 3 h2o co2 nacl h2s n2 ch4 fluid 2 a high temperature up to 445 c hypersaline 40 wt nacl equiv high density 1 3 g cm 3 h2o co2 nacl fecl2 fluid partial mixing of these fluids within the jog zone at gounkoto enhanced phase separation in the aqueo carbonic fluid and acted as a precipitation mechanism for au these findings demonstrate the widespread if heterogeneously distributed nature of fluid mixing as an ore forming process in the loulo gounkoto complex operating over at least a 30 km strike length of the shear zone stable isotope analyses of ore components at gounkoto indicate a dominant metamorphic source for h2o h2s and co2 and by extension au it thus can be reasoned that both the aqueo carbonic and the hypersaline fluid at gounkoto are of metamorphic origin and that the high levels of salinity in the brine are likely derived from evaporite dissolution

western caribbean intraplate deformation defining a continuous and active microplate boundary along the san andres rift and hess escarpment fault zone colombian caribbean sea the san andres rift sar located on the lower nicaraguan rise is a previously poorly studied active 015 trending bathymetric and structural rift basin that is 11 27 km 7 17 mi wide and extends for 346 km 215 mi across the western flank of the caribbean plate in this study we integrate bathymetric maps potential field data and high resolution two dimensional 2 d seismic lines to understand the crustal structure tectonic history and tectonic origin of the sar which is one of the active areas within the otherwise stable caribbean plate we compiled regional gravity and magnetic data that revealed a negative gravity anomaly and positive magnetic anomaly that we interpret as a result of crustal thinning and an elevated moho along the main rift axis of the sar forward models of gravity data show four possible interpretations for the origin of the crust underlying and surrounding the sar interpretations of 2 d seismic reflection data show structural features within the upper crust and sedimentary sections typical of other active rift systems including a sar parallel north south alignment of earthquakes with the larger events showing normal and strike slip focal mechanisms sequential kinematic restorations based on 2 d seismic profiles reveal three major phases of sar opening 1 the initial early eocene rifting stage 2 middle eocene extension and 3 a rapid middle miocene to early pliocene extension accompanied by emergence of the san andres island as a rift shoulder we propose slab rollback and intraplate extension as main tectonic mechanisms to explain all rift phases and neogene volcanism found in the western caribbean region

the response of suspended particulate material to upwelling and downwelling events in southern lake michigan abstract time series measurements of water temperature beam attenuation and current velocity were made at three stations located in 28 58 and 100 m of water off the east coast of lake michigan from late august until mid october 1995 when combined with water intake records and wave measurements our observations show that local resuspension is not responsible for maintaining the benthic nepheloid layer bnl during the stratified period resuspension of bottom material by surface wind waves occurs in shallow water 13 m but this material is not transported offshore into the bnl during downwelling events during upwellings material may be transported onshore from the bnl into shallow water but additional material is required to produce the concentrations observed at the inner stations resuspension by internal waves may be the source of this additional material changes in the vertical structure of the benthic nepheloid layer appear to account for most of the changes in suspended particulate material at the two offshore stations these changes are probably due to a combination of internal wave action and regional changes in current patterns

does local resuspension maintain the benthic nepheloid layer in southeastern lake michigan time series observations of water temperature water transparency and current velocity at four stations in southeastern lake michigan show that the benthic nepheloid layer is probably not maintained by the local resuspension of bottom sediment local resuspension may occasionally occur in the deep parts of the lake but it seems likely that vertical mixing and offshore advection of sediment laden water maintain the benthic nepheloid layer during most of the year although sediment trap data have been interpreted as indicating that local resuspension does occur it is more likely that the increased sediment fluxes observed near the bottom are due to vertical redistribution of material already in suspension

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

quaternary flake tectonics of the california transverse ranges p residual studies suggest that the pacific american plate boundary in the upper mantle lies in the central mojave desert northeast of its crustal position at the san andreas fault focal mechanisms of some relatively deep microearthquakes suggest a flattening with depth of north dipping thrust faults resulting in a mid crustal detachment in which the central transverse ranges move south relative to the mantle this makes sense geologically if the central transverse ranges and western mojave desert are considered as tectonic flakes of brittle crystalline rocks underlain by ductile pelona schist or catalina schist which makes up the zone of decollement such ductile schists would occur today at depths comparable to those at which they were metamorphosed the detachment breaks through to the surface at the point dume malibu coast fault zone and the red mountain san cayetano santa susana sierra madre cucamonga fault zone the latter coinciding with the southern edge of the palmdale bulge the transverse ranges flake now moves west northwest relative to the western mojave flake south southwest relative to the pacific plate and northwest relative to the great valley sierra nevada the mantle boundary may rejoin the san andreas fault north of a southwest trending zone of high seismicity in the tehachapi mountains which may be produced by convergence the age of the present tectonic system may be the same as the age of the break through thrust faults these are probably no older than 2 m y and may be even younger

imaging thermal stratigraphy in freshwater lakes using georadar 1 thermal stratification exerts significant control over biogeochemical processing in freshwater lakes thus the temporal and spatial distribution of the thermal structure is an important component in understanding lake ecosystems we present the first reported observations of lake thermal stratification from surface based georadar measurements acquired over two small freshwater lakes this method is very useful because it can provide rapid acquisition of 2d or 3d lotic stratification

diffusion and fluid interaction in itrongay pegmatite madagascar evidence from in situ 40ar 39ar dating of gem quality alkali feldspar and u pb dating of protogenetic apatite inclusions alkali feldspar 40ar 39ar and apatite upb geochronological studies have typically invoked two mechanisms to account for apparent loss of radiogenic 40ar and 206 208pb some studies have suggested that the radiogenic isotopes were lost by volume diffusion and used these dates to constrain temporal variations of rock temperatures others have argued that the radiogenic isotopes were lost due to interaction with fluids and related these dates to chemical alteration these two end member interpretations have fundamentally different implications for tectonic models derived from geochronological data and therefore it is important to reliably identify the principal mechanism for loss of radiogenic isotopes here we revisit the mechanisms of 40ar loss in the famous gem quality alkali feldspar from the itrongay pegmatite in madagascar previous studies have suggested that volume diffusion is the dominant mechanism of 40ar loss providing key evidence to support the use of 40ar 39ar dating of alkali feldspar for thermochronology we attempted to verify these results by obtaining time temperature paths from petrologically characterised cogenetic feldspar and apatite from the itrongay pegmatite and comparing them with each other however our results suggest that only a minor component in the variability of 40ar 39ar dates of itrongay feldspar is related to the diffusive loss of 40ar and that this loss was not compatible with the majority of previously proposed models which hinders quantitative interpretations the crystal studied here grew in five episodes related to the influx initially of co existing dense sio2 rich solution and co2 dominated fluid the first and supposedly the following two episodes and subsequently of h2o rich fluid supposedly the final two episodes much greater component in the variability of the acquired 40ar 39ar dates is interpreted to reflect the differences in the ages of these growth episodes which we estimate to span from 477 ma to 176 ma the first four episodes apatite inclusions in this crystal are interpreted to be xenocrysts derived from the country rocks of the itrongay pegmatite these yield older upb dates than the estimated age of their host feldspar and have apparently experienced diffusive loss of 206 207pb prior to entrapment our 40ar 39ar results indicate that there is a lack of unambiguous evidence for diffusive loss of 40ar from alkali feldspar that can be readily interpreted for thermochronological purposes however in situ 40ar 39ar dating of alkali feldspar appears to be a promising tool for tracking fluid flow events in the earth s crust whose applicability is not restricted to sedimentary rocks our upb results corroborate previous suggestions that upb dating of apatite can be used for thermochronology

structure and earthquake offsets on the san andreas fault at the wrightwood california paleoseismic site thirty eight trenches and natural exposures across the san andreas fault zone four km northwest of wrightwood california reveal the structure and stratigraphy of this paleoseismic site a 25 m thick stratigraphic section of late holocene peat debris flows and fluvial sediments have accumulated syntectonically and are deformed in a complicated flower or flake structure within the fault zone whereas slip is everywhere parallel to the trend of the san andreas fault layering within the fan shaped section guides the surface faulting and transtensive portions of the structure are connected to transpressive portions by bedding parallel detachment faults the structure has grown through time widely distributing the evidence for individual earthquakes the broad zone of deformation and rapid sedimentation permit the characterization of an unusually large number of prehistoric earthquakes the presence of at least four geomorphically similar sites within 10 km along the fault zone suggests that this kind of site is common and other sites should be exploited to date the upper 12 m of section deposited during the past 1600 yr has been completely characterized and dated to show evidence of 14 prehistoric earthquakes the a d 1857 earthquake produced only 1 2 m of slip here commensurate with the site9s proximity to the southern end of the rupture six to 10 m of slip accumulated during the past three earthquakes and 30 60 m of cumulative slip occurred during the past 14 events suggesting a mean displacement of 2 4 m per event at the site coupled with the mean recurrence interval of slightly more than 100 yr this implies a slip rate of 2 4 cm yr for the san andreas fault north of its junction with the san jacinto fault

study of hydrocarbon generation and 1d 2d modeling of hydrocarbon migration at the karanj and parsi oilfields southern dezful embayment sw iran abstract this study is a 2d basin modeling to determine the petroleum system i e cretaceous neogene play of the karanj and parsi oilfields in the southern dezful embayment sw iran this system is characterized by occurrence of source rocks of middle cretaceous late cretaceous and paleocene to eocene kazhdumi pabdeh and gurpi formation reservoirs of upper cretaceous and late oligocene early miocene ilam sarvak and asmari formations and seals of paleocene and miocene pabdeh and gachsaran formation considering temperature transformation ratio and vitrinite reflectance the maturity of source rocks kazhdumi pabdeh and gurpi formation was investigated a maturity history analysis showed that the maturity of kazhdumi pabdeh and gurpi formation started during 70 60 and 4 ma respectively generation and expulsion of hydrocarbons started 16 ma in the kazhdumi formation and 3 ma in the pabdeh formation that continued up to the present the analysis of the transformation ratio indicates transformation of significant amounts of kazhdumi source rocks for generating hydrocarbons migration of hydrocarbons from the kazhdumi formation is mainly vertically upward from pabdeh formation migration is both vertically upward to the asmari reservoir and downwards to the ilam sarvak reservoir however some local traps have formed due to the hydrocarbon accumulation above the faults our results reveal that petroleum generation migration and entrapment occurred at proper timing which facilitated the migration of hydrocarbons and their accumulation in the reservoirs