flowgo a kinematic thermo rheological model for lava flowing in a channel we present a kinematic self adaptive numerical model to describe the down flow thermal and rheological evolution of channel contained lava as our control volume of lava advances down a channel it cools and crystallizes an increasingly thick and extensive surface crust grows and its heat budget and rheology evolve by estimating down flow heat and velocity loss our model calculates the point at which the control volume becomes stationary giving the maximum distance lava flowing in the channel can extend modeled effusion rates velocities widths surface crust parameters heat budget cooling temperature crystallinity viscosity and yield strength all compare well with field data collected during eruptions at mauna loa k lauea and etna modeled lengths of 25 27 2 5 5 7 and 0 59 0 83 km compare with measured lengths of 25 27 4 and 0 75 km for the three flows respectively over proximal flow portions we calculate cooling crystallization viscosity and yield strength of 1 10 c km 1 0 001 0 01 volume fraction km 1 103 104 pa s and 10 3 102 pa respectively at the flow front cooling crystallization viscosity and yield strength increase to 100 c km 1 0 1 volume fraction km 1 106 107 pa s and 103 104 pa respectively all of which combine to cause the lava to stop flowing our model presents a means of a analyzing lava flow thermo rheological relationships b identifying important factors in determining how far a channel fed flow can extend c assessing lava flow hazard and d reconstructing flow regimes at prehistoric unobserved or remote flows

field temperature measurements at erta ale lava lake ethiopia the shield volcano erta ale situated in the danakil depression ethiopia is known for its active lava lake in february 2001 our team visited this lake located inside an 80 m deep pit to perform field temperature measurements the distribution and variation of temperature inside the lake were obtained on the basis of infrared radiation measurements performed from the rim of the pit and from the lake shores the crust temperature was also determined from the lake shores with a thermocouple to calibrate the pyrometer we estimated an emissivity of the basalt of 0 74 from this experiment through the application of the stefan boltzmann law we then obtained an estimate of the total radiative heat flux constrained by pyrometer measurements of the pit and visual observations of the lake activity taking into account the atmospheric convective heat flux the convected magma mass flux needed to balance the energy budget was subsequently derived and found to represent between 510 and 580 kg s 1 the surface circulation of this mass flux was also analyzed through motion processing techniques applied to video images of the lake electronic supplementary material to this paper can be obtained by using the springer link server located at http dx doi org 10 1007 s00445 002 0224 3

shallow magma transport for the 2002 3 mt etna eruption inferred from thermal infrared surveys abstract the 26 october 2002 28 january 2003 eruption of mt etna volcano was characterised by lava effusion and by an uncommon explosivity along a 1 km long eruptive fissure on the southern upper flank of the volcano the intense activity promoted rapid growth of cinder cones and several effusive vents analysis of thermal images recorded throughout the eruption allowed investigation of the distribution of vents along the eruptive fissure and of the nature of explosive activity the spatial and temporal distribution of active vents revealed phases of dike intrusion expansion geometric stabilization and drainage these phases were characterised by different styles of explosive activity with a gradual transition from fire fountaining through transitional phases to mild strombolian activity and ending with non explosive lava effusion here we interpret the mechanisms of the dike emplacement and the eruptive dynamics according to changes in the eruptive style vent morphology and apparent temperature variations at vents detected through thermal imaging this is the first time that dike emplacement and eruptive activity have been tracked using a handheld thermal camera and we believe that its use was crucial to gain a detailed understanding of the eruptive event

distribution of active glaciers and rock glaciers compared to the distribution of permafrost landforms based on freezing and thawing indices climatic stations near glacial termini and equilibrium lines show a distribution of freezing and thawing indices that does not conform to the boundaries derived from data for stations in areas of continuous and discontinuous permafrost active tongue shaped rock glaciers have similar limits of freezing and thawing indices to the equilibrium lines of glaciers while active lobate rock glaciers have limits paralleling the limit for stations in the zone of continuous permafrost this difference between the distributions of lobate and tongue shaped rock glaciers explains why the active tongue shaped rock glaciers can be used for indicating the limits of the permafrost areas in the alps a maritime regime but cannot be used in that way in continental climates e g alberta interior yukon and the northwest territories

birth growth and morphologic evolution of the laghetto cinder cone during the 2001 etna eruption we have undertaken detailed observations of the formation of the laghetto cinder cone a new cone that formed during a 2 week period of intense activity in piano del lago on the upper slopes of mount etna in summer 2001 we describe the events leading to the formation of a small graben the formation of pit craters on the base of the graben the onset of phreatomagmatic activity a transition to intense strombolian activity and a return to phreatomagmatic activity as the eruption came to an end we discuss the reasons for these transitions and describe the morphological development of the cone during these events arcuate cracks on the southern part of the cone were related to withdrawal of magma at the end of the eruption other slope instabilities that developed during the eruption include the formation of small radial grain flows on the outer flanks of the cone and the collapse into the crater of part of the crater rim some of the failure planes we observed were first identified using a flir tm 695 thermal infrared camera this is the first time that infrared thermography has been used to detect instability of volcanic structures results obtained during this test case demonstrate that thermal cameras are a very useful tool for studies of volcanic instability

geochemistry and textures of gold bearing arsenian pyrite twin creeks nevada implications for deposition of gold in carlin type deposits this study relates morphology size texture and chemistry of arsenian pyrite in the twin creeks carlin type gold deposits to the chemical position and amount of gold that it contains arsenian pyrite is confirmed as the most important gold hosting mineral and four types of gold bearing arsenian pyrite are recognized among these four types the lowest amount of gold and arsenic 1 wt as 17 60 ppm au is contained in arsenian pyrite with relatively large grain sizes 10 30 mu m it formed at relatively high temperatures 250 degrees c and k super h super ratios adularia stable probably relatively slowly the largest amount of gold and arsenic 1 05 2 43 wt as 595 1 465 ppm au is contained in arsenian pyrite with small grain sizes up to 2 mu m that formed at low temperatures 120 degrees 200 degrees c and moderate k super h super ratios illite stable probably by relatively rapid deposition xanes exafs and sims analyses show that gold in arsenian pyrite is both structurally bound au i and in submicroscopic inclusions of free gold au highest amounts of structurally bound gold were observed in the relatively coarse grained arsenian pyrite noted above whereas most inclusions of free gold were observed in fine grained arsenian pyrite in general there is a good correlation between gold and arsenic in arsenian pyrite although au as ratios vary from one pyrite to another it is suggested that gold in arsenian pyrite was deposited by direct deposition of native gold and by adsorption of au i from hydrothermal solutions adsorption of gold by arsenian pyrite can take place from solutions that are not saturated with respect to native gold relative volumes of gold bearing pyrite from different paragenetic stages at twin creeks suggest that as much as 50 percent of the total gold in the deposit could have formed from solutions that were not saturated with respect to native gold because both au and au i are found together in arsenian pyrite it is likely that they were deposited by the same process consideration of possible depositional reactions suggests that a decrease in the activity of reduced sulfur is most likely to cause gold deposition

oblique photogrammetry with visible and thermal images of active lava flows digital images from hand held cameras are increasingly being acquired for scientific purposes particularly where non contact measurement is required however they frequently consist of oblique views with significant camera to object depth variations and occlusions that complicate quantitative analyses here we report the use of oblique photogrammetric techniques to determine ground based thermal camera orientations position and pointing direction and to generate scene information for lava flows at mount etna sicily multiple images from a consumer grade digital slr camera are used to construct a topographic model and reference associated ground based thermal imagery we present data collected during the 2004 2005 eruption and use the derived surface model to apply viewing distance corrections to account for atmospheric attenuation to the thermal images on a pixel by pixel basis for viewing distances of 100 to 400 m the corrections result in systematic changes in emissive power of up to 3 with respect to values calculated assuming a uniform average viewing distance across an image

surface cooling advection and the development of different surface textures on active lavas on kilauea hawai i the validity of lava flow cooling models were investigated using data from a high resolution high frame rate thermal imaging camera on kilauea hawai i during august 2004 once the surface temperature data for small lava flow and lobes were corrected for emissivity viewing distance humidity and viewing angle it was clear that their upper surfaces were thermally stratified on eruption the interior of a stationary lava lobe was exposed by removing the crust and its cooling rate was measured at 30 hz for this flow the measured cooling trend was successfully modelled using a finite difference cooling model however modelled and measured cooling rates of a pahoehoe lobe and a small channelised lava flow were only in agreement until the crust began to deform the departure from the modelled trend at this point is attributed to two factors one is the complex cooling regime of a highly deformed ropy crust in which exposed lava at the crests of the ropes radiates in all directions compared with lava in the troughs where radiative cooling is less effective the second and more important reason for the difference is the reduced flow rate of the crust once it begins to be compressed the underlying visco elastic zone beneath the crust flows more rapidly than the crust and consequently advective heat flow significantly reduces cooling rates variations in heat loss from different flow textures and the incorporation of different advective heat components is clearly important in future flow models one of the critical parameters in such models is the temperature at which different surface textures develop temperature profiles along lobes and flows also revealed that rope textures developed on pahoehoe lavas when temperatures were in the range of 700 800 c brittle deformation of pahoehoe crust occurred when temperature dropped below 700 c and small pahoehoe lobes stopped advancing at temperatures of 600 650 c it is important to recognise that the flow front temperatures at which these flows stop advancing will be significantly greater than for larger flows on similar gradients the higher internal and basal shear stresses of large lava flows will allow the flow to advance until the visco elastic layer at the front of a front is significantly cooler than the temperatures recorded on these small flows on kilauea

reactivation of stromboli s summit craters at the end of the 2007 effusive eruption detected by thermal surveys and seismicity this paper was partially supported by a grant to s c project ingv dpc paroxysm v2 03 2008 2010 funded by the istituto nazionale di geofisica e vulcanologia and by the italian civil protection

geological fluid inclusion h o s pb isotope and ar ar geochronology constraints on the genesis of the nancha gold deposit southern jilin province northeast china abstract the nancha gold deposit located in the central part of southern jilin province in the northeastern portion of the north china craton contains orebodies hosted in a proterozoic metamorphosed volcanic sedimentary sequence the distribution of the orebodies is controlled by nne trending brittle ductile shear zones and faults the gold orebodies consist of auriferous quartz veins and auriferous altered rocks mineralization can be divided into three stages 1 quartz pyrite 2 quartz gold polymetallic sulfide and 3 quartz carbonate with gold being introduced mainly in the second stage three types of fluid inclusions were identified in the vein mineral assemblages based on petrography and laser raman spectroscopy nacl h 2 o w type co 2 h 2 o c type and pure co 2 pc type crystals in the early quartz pyrite stage veins mainly contain c type primary fluid inclusions and rare pc type inclusions the fluid inclusions in these veins completely homogenize at temperatures of 273 432 c and show low salinities of 0 63 7 78 wt nacl equiv in the middle quartz gold polymetallic sulfide stage all three types of fluid inclusions were observed these fluid inclusions homogenize at temperatures of 132 to 255 c and show salinities of 0 83 11 72 wt nacl equiv in contrast crystals in the late quartz carbonate stage contain only w type fluid inclusions that show homogenization temperatures of 132 255 c and salinities of 0 35 7 86 wt nacl equiv these data indicate that the metallogenic system evolved from a co 2 rich metamorphogenic fluid to a co 2 poor fluid due to inputs of meteoric waters fluid boiling and mixing caused the rapid precipitation of sulfides and gold trapping pressures estimated from boiling c type fluid inclusions were 152 367 mpa in the ore forming stage this suggests an alternating lithostatic hydrostatic fluid system controlled by a fault valve activity at a depth of 13 8 15 2 km one hydrothermal sericite sample from an auriferous quartz vein yielded an 40 ar 39 ar isotopic plateau age of 170 1 1 9 ma indicating that mineralization occurred in the middle jurassic and was unrelated to the volcanics and intrusions in the mineralized area the characteristics of h o s pb isotopes and fluid inclusions suggest that the ore forming fluids were of metamorphic origin with the s originating from proterozoic crustal components and the pb originating from a mixture of ore forming metamorphogenic fluids and host rocks the results combined with existing data on the regional geology ore geology fluid inclusions h o s pb isotope geochemistry age of mineralization and tectonic setting indicate that the nancha gold deposit was an orogenic type system that formed in a middle jurassic accretionary orogenic regime following subduction of the paleo pacific plate beneath the eurasian continent

genesis and age of the toudaoliuhe breccia type gold deposit in the jiapigou mining district of jilin province china constraints from fluid inclusions h o s pb isotopes and sulfide rb sr dating abstract the jiapigou mining district jmd in the northeastern part of the north china block mainly contains quartz vein and altered rock type gold deposits that have been prospected and mined for over 200 years recently a breccia type gold deposit known as toudaoliuhe was discovered in the jmd that has attracted attention for prospecting and exploration in this paper we report the ore geology gold bearing sulfide i e pyrite galena and sphalerite rb sr age fluid inclusions fis and h o s pb sr isotope data of the toudaoliuhe gold deposit to determine its genesis and ore forming mechanisms gold orebodies mainly occur in the breccia cements as well as in several quartz veins controlled by nw trending brittle faults there were three hydrothermal stages the early quartz pyrite main quartz polymetallic sulfide and late quartz carbonate stages gold mineralization occurred in the main hydrothermal stage three types of fis were identified co2 h2o nacl c type h2o nacl w type and pure co2 pc type the fis in quartz from the early hydrothermal stage are predominantly of the c and w types with traces of pc type and have homogenization temperatures of 299 8 340 0 c and salinities of 6 5 14 8 wt nacl equivalent e the fis in the quartz and sphalerite forming the main hydrothermal stage are also predominantly of the c and w types with trace pc type and have homogenization temperatures of 169 1 298 7 c and salinities of 5 7 16 5 wt e the fis in the quartz and calcite from the late hydrothermal stage were solely of the w type and have homogenization temperatures of 126 0 210 2 c and salinities of 2 1 11 4 wt e the ore forming fluids are characterized by moderate temperature and low salinity suggesting a co2 h2o nacl system the h o s pb sr isotopic results suggest that the ore forming fluids were dominated by magmatic water and that the ore forming materials were mainly extracted from the middle jurassic magmatic reservoir 177 163 ma sourced mainly from the lower crust with trace mantle components fluid boiling was the dominant mechanism for gold and associated sulfide precipitation the rb sr isochron age of the gold bearing sulfides at 177 7 1 7 ma indicates that gold mineralization occurred in the early middle jurassic we therefore proposed that the toudaoliuhe is a mesothermal gold deposit that formed in an extensional setting related to the subduction of the paleo pacific plate beneath the eurasian continent

pulsed lava effusion at mount etna during 2001 effusion rate and degassing data collected at mt etna volcano italy in 2001 show variations occurring on time scales of hours to months we use both long and short term data sets spanning january to august to identify this variation the long data sets comprise a satellite and ground based time series of effusion rates and the latter include field based effusion rate and degassing data collected may 29 31 the satellite derived effusion rates for january through august reveal four volumetric pulses that are characterized by increasing mean effusion rate values and lead up to the 2001 flank eruption peak effusion rates during these 23 57 day pulses were 1 2 m 3 s 1 in pulse 1 1 jan 4 mar 1 1 m 3 s 1 in pulse 2 5 mar 21 apr 4 2 m 3 s 1 in pulse 3 24 apr 18 jun 8 8 m 3 s 1 in pulse 4 23 jun 16 jul and 22 2 m 3 s 1 during the flank eruption 17 jul 9 aug rank order analysis of the satellite data shows that effusion rate values during the 2001 flank eruption define a statistically different trend than etna s persistent activity from jan 1 to jul 17 data prior to the flank eruption obey a power law relationship that may define an effusion rate threshold of f3 5 m 3 s 1 for etna s typical persistent activity our short term data coincide with the satellite derived peak effusion period of pulse 3 degassing at vent puff frequency shows a general increase from may 29 to 31 with hour long variations in both puff frequency and lava flow velocity effusion rate we identify five 3 14 h degassing periods that contain 26 shorter 19 126 min long oscillations this variation shows some positive correlation with effusion rate measurements during the same time period if a relationship between puff frequency and effusion rate is valid we propose that their short term variation is the result of changes in the supply rate of magma to the near vent conduit system therefore these short term data provide some evidence that the clear weeks to months long variation in etna s effusive activity january august 2001 was overprinted by a minutes to hour scale oscillation in shallow supply d 2004 elsevier b v all rights reserved

temperature of an active lava channel from spectral measurements kilauea volcano hawaii a narrow band spectroradiometer was used to determine the characteristic temperatures of a very active channeled lava flow for the phase 50 eruption of pu u o o on the east rift zone of kilauea volcano hawaii during the twilight of 19 february 1992 14 spectra of this activity were acquired over a 51 minute interval 18 29 to 19 20 hawaiian standard time hst from which the thermal distribution of energy of two 18 m2 areas one near the center and one near the margin of the flow may be investigated a twocomponent thermal mixing model applied to the data taken of the center of the channel gave in the most powerful instance 1 8x105 w m2 a crust temperature of 940 c a hot component temperature of 1120 c and a hot radiating area of 60 of the total area a simultaneous spectrum acquired near the channeled flow margin yielded a crust temperature of 586 c and a hot area of only 1 2 of the total area radiating at 1130 c average radiant flux densities recorded for the center of the lava channel 1 3x105 w m2 average are much greater than previous measurements of lava lakes 4 9x103 w m2 or recently emplaced lava flows maximum of 7 2x104 w m2 the energetic nature of this eruption is shown by satellite measurements made at 02 33 hst on 22 february 1992 by the advanced very high resolution radiometer in band 2 0 72 1 10 m these show the utility of using existing satellites with moderate resolution 1 km x 1 km pixels and high temporal coverage eight overpasses each day for hawaii as potential thermal alarms for rapidly assessing the hazard potential of large volcanic eruptions

timing and evolution of jurassic cretaceous granitoid magmatisms in the mongol okhotsk belt and adjacent areas ne asia implications for transition from contractional crustal thickening to extensional thinning and geodynamic settings abstract the mongol okhotsk belt and adjacent areas are key areas to study the relationship between the okhotsk and paleo pacific tectonic regimes and their superposition on the older paleo asian regimes during late mesozoic times this paper summarizes the spatial temporal evolution of late mesozoic jurassic cretaceous granitoids and related intrusions in these areas and interprets the magmatic evolution in terms of a transition from contractional crustal thickening to extensional thinning according to 407 published zircon ages these granitoids were mainly emplaced during the intervals 200 180 ma 180 165 ma 165 145 ma 145 135 ma and 135 100 ma jurassic granitoids 200 145 ma predominately occur in the baikal ne mongolia bnem and great xing an range early cretaceous 145 100 ma granitoids are mainly occur in the great xing an range and display a southward younging migration significantly early cretaceous granitoids also extend into the trans baikal area across the mongol okhotsk suture far away from the paleo pacific plate margin in ne china thus they were more plausibly related to post orogenic collapse of the mongol okhotsk orogen from the late jurassic to early cretaceous the granitoids evolved compositionally from calc alkaline and high k calc alkaline i type with some adakite like features to high k calc alkaline and shoshonitic highly fractionated i transitional i a or a type characterized by a significant decrease in their sr y ratios this evolution coincided with a tectonic transition from contractional crustal thickening to extensional thinning combined with regional geology we speculate that the jurassic granitoids were likely derived from melting of the deep seated thickened lower continental crustal lcc sources whereas the cretaceous granitoids produced through crustal melting from an extensional thinning setting our results provide a case study demonstrating that the petrogenesis of granitic magmatism was closely associated with crustal tectonics early jurassic granitoids along the okhotsk belt formed in a subduction collision setting related to closure of the mongol okhotsk ocean whereas late jurassic granitoids in the great xing an range and in the northern north china craton may have formed in a syn or post collisional setting superposed by far field affects of subduction of the paleo pacific plate early cretaceous granitoids in these areas formed in response to post orogenic extensional collapse of the mongol okhotsk belt coupled with back arc extension related to paleo pacific plate subduction

metamorphic origin of ore forming fluids for orogenic gold bearingquartz vein systems in the north american cordillera constraints froma reconnaissance study of δ15n δd and δ18o the western north american cordillera hosts a large number of gold bearing quartz vein systems from the mother lode of southern california through counterparts in british columbia and southeastern alaska to the klondike district in central yukon these vein systems are structurally controlled by major fault zones which are often reactivated terrane bounding sutures that formed in orogens built during accretion and subduction of terranes along the continental margin of north america mineralization ages span mid jurassic to early tertiary and encompass much of the evolution of the cordilleran orogen nitrogen contents and 15n values of hydrothermal micas from veins are between 130 and 3 500 ppm and 1 7 to 5 5 per mil respectively these values are consistent with fluids derived from metamorphic dehydration reactions within the phanerozoic accretion subduction complexes which have 15n values of 1 to 6 per mil the 18o values of gold bearing vein quartz from different locations in the cordillera are between 14 6 and 22 2 per mil but are uniform for individual vein systems the d values of hydrothermal micas are between 110 and 60 per mil ore fluids have calculated 18o values of 8 to 16 per mil and d values of 65 to 10 per mil at an estimated temperature of 300 c d values of ore fluids do not show any latitudinal control these results indicate a deep crustal source for the ore forming fluids most likely of metamorphic origin low dh2o values of 120 to 130 per mil for a hydrous muscovite from the sheba vein in the klondike district reflect secondary exchange between recrystallizing mica and meteoric waters collectively the n h and o isotope compositions of ore related hydrothermal minerals indicate that the formation of these gold bearing veins involved dilute aqueous carbonic and nitrogen bearing fluids that were generated from metamorphic dehydration reactions at deep crustal levels these data are not consistent with either mantle derived fluids or granitoid related magmatic fluids nor do they support a model involving deeply circulated meteoric water

hydrothermal characterization of the west gore sb au deposit meguma terrane nova scotia canada the west gore sb au deposit is anomalous in the megurea terrane of nova scotia because of its enrichment in sb a metal that is essentially absent from other megurea gold deposits the deposit is hosted by graphitic and sulfide bearing slates of the lower paleozoic halifax formation that were deformed into a northeast trending upright closed syncline and metamorphosed to the greenschist facies during the regional acadian orogeny ca 400 ma mineralized veins at the deposit define a single structure trending 110 degrees that probably formed the dextral component of a conjugate shear system as part of regional northwest directed compression the veins crosscut a penetrative regional schistosity s 1 in the host slates and vein formation is constrained by 1 the presence of cleaved wall rock slates in the veins 2 vein related sulfides overgrowing the s 1 fabric in wall rock fragments and 3 a 370 ma 40 ar 39 ar plateau age for hydrothermal muscovite mineralization occurs as stibnite native antimony aurostibnite au sb alloys and au sb o phases in vein quartz with associated fe as pb zn cu sulfides and chlorite carbonate gangue wall rock alteration is variably developed as narrmv zones peripheral to veins enriched in sericite calcite sulfides tourmaline and chlorite early stages of mineralization are constrained to maximum temperatures of 495 degrees c from arsenopyrite geothermometry but lower temperatures are recorded by chlorite geothermometry 350 degrees 390 degrees c textures of vein quartz include comb and plumose varieties with a bimodal grain size and also a coarser anhedral quartz fluid inclusion studies indicate that the fluid was a mixed h 2 o nacl cacl 2 co 2 ch 4 type and that fluid unmixing occurred albeit in minor amounts thermometric measurements reveal maximum t h of 375 degrees c and a range of salinities 0 4 28 1 wt nacl equiv the volumetric properties of fluid inclusions reflect cycling of fluid pressures with supralithostatic pressures to 4 5 kbars p fluid recorded by the presence of h 2 o co 2 inclusions to 20 mole co 2 which are interpreted to have resulted from fluid rock interaction subsequent reduction in fluid pressures to ca 2 kbars resulted in decreasing amounts of co 2 1 2 mole and fluid unmixing that generated higher and lower salinity trends observed in t h salinity plots vein forming fluids are characterized by delta 13 c sub sigma c 19 5 to 22 6 per mil delta 18 o sub h 2 o 9 to 15 per mil delta d 42 to 64 per mil and delta 34 s sub h 2 s 9 7 to 10 3 per mil based on analysis of calcite quartz fluid inclusion extracts in quartz and stibnite vein tourmaline associated with stibnite has 87 sr 86 sr measured of 0 71707 to 0 72284 these data are consistent with a metamorphic origin for the fluid with local inheritance of c and s isotope signatures from interaction of the ore fluid with graphite and sulfide wall rock slates of the halifax formation the west gore deposit originated from infiltration of metamorphic derived fluids generated during the waning stages of the acadian orogeny contemporaneous with generation and emplacement of felsic and mafic magmas the mineralizing fluids were focused to higher crustal levels p fluid ca 2 kbars where brittle ductile conditions prevailed and veins were localized to the dextral component of a conjugate shear system related to movement along a major dextral strike slip fault or shear zone cobequid chedabucto fault system deposition of vein constituents resulted from a decrease in temperature and changes in fluid chemistry decrease in f sub s 2 and f sub o 2 induced by fluid unmixing and interaction with the wall rock lithogeochemistry of the local stratigraphy does not indicate any regional enrichment in sb au or other metals the occurrence of the stibnite may therefore reflect either telescoping of metals in a au w sb province or enrichment of sb in the source area or fluid conduit relative to other meguma gold deposits

calculation of lava effusion rates from landsat tm data we present a thermal model to calculate the total thermal flux for lava flowing in tubes on the surface or under shallow water once defined we use the total thermal flux to estimate effusion rates for active flows at kilauea hawaii on two dates input parameters were derived from landsat thematic mapper tm field and laboratory measurements using these parameters we obtain effusion rates of 1 76 0 57 and 0 78 0 27 m3 s 1 on 23 july and 11 october 1991 respectively these rates are corroborated by field measurements of 1 36 0 14 and 0 89 0 09 m3 s 1 for the same dates kauahikaua et al 1996 using weather satellite avhrr data of lower spatial resolution we obtain similar effusion rates for an additional 26 dates between the two tm derived measurements we assume that although total effusion rates at the source declined over the period the shut down of the ocean entry meant that effusion rates for the surface flows alone remained stable such synergetic use of remotely sensed data provides measurements that can a contribute to monitoring flow field evolution and b provide reliable numerical data for input into rheological and thermal models we look forward to being able to produce estimates for effusion rates using data from high spatial resolution sensors in the earth observing system eos era such as landsat 7 the hyperspectral imager the advanced spaceborne thermal emission spectrometer and the advanced land imager

surface textures and dynamics of the 2005 lava dome at shiveluch volcano kamchatka shiveluch is one of the largest and most active andesitic volcanoes of the kuril kamchatka arc it commonly alternates between vulcanian explosive eruptions and periods of dome growth and subsequent dome collapse driven block and ash flows the volcano was in an extended period of heightened activity for most of the period 2004 2010 we examined this activity in detail using thermal infrared tir remote sensing as part of the urgent request protocol urp program of the advanced spaceborne thermal emission and reflection radiometer aster instrument and confirmed the results with ground based photography and airborne tir camera data high spatial resolution tir images were collected during both daytime and nighttime satellite overpasses prior to and following the large explosive event eruption of 27 february 2005 and the dome growth that followed during a field campaign in august 2005 a helicopter overflight designed to acquire visible and tir data of the active dome was performed this was a nadir looking low altitude overflight and the first ever of shiveluch volcano involving non russian scientists the image data revealed an active crease structure in the center of the dome with a distinctly different crescent shaped high temperature 380 c zone roughly perpendicular to the crease in order to provide a time context and estimate extrusion rates the airborne data were compared to the spaceborne aster data and long distance ground based photography of the dome acquired by our russian colleagues the presence of a crease structure and the complex thermal pattern on the surface were both unexpected discoveries that reveal the way in which exogenous dome growth was occurring at the time this highly active period at shiveluch provides a unique example to better understand silicic lava dome growth using tir data the results also demonstrate a straightforward approach for fusing ground air and spaceborne image data which could be applied to other active domes around the world

flash vaporization during earthquakes evidenced by gold deposits fluids flowing through cavities in earth s crust can deposit gold thermo mechanical modelling of a fluid filled cavity that expands suddenly during an earthquake shows that the drop in pressure would cause the fluid to vaporize and deposit the gold almost instantaneously

geochronological and he ar s isotopic constraints on the origin of the sandaowanzi gold telluride deposit northeastern china abstract northeastern china is characterized by widespread mesozoic volcanic rocks and au cu mo mineral deposits with a total gold reserve of 2000 t amongst those gold deposits the newly discovered sandaowanzi has a total reserve of 25 t of au and an average grade of 15 g t this deposit is important because it is the first reported case of a dominantly au ag telluride deposit containing economically valuable bonanza au and ag telluride ores in the region the sandaowanzi quartz vein system and associated au ag telluride mineralization are mainly hosted by trachyandesites and andesitic breccias native gold is closely associated with abundant tellurides including petzite sylvanite calaverite hessite and altaite twelve pyrite samples from the alteration zone yield a well defined rb sr isochron age of 119 1 3 9 ma which is in agreement with a robust rb sr isochron age of 121 3 2 6 ma derived from 10 auriferous quartz samples the obtained isochron age of 120 ma represents the formation of the sandaowanzi gold telluride epithermal system which is much younger than the host trachyandesite with a zircon u pb age of 312 5 0 5 ma and the spatially associated monzogranite with a zircon u pb age of 182 2 1 1 ma dating results indicate a close relationship between the local au ag te mineralization and a magmatism episode in the early cretaceous noble gas he and ar isotopes obtained from telluride sulfide and quartz and sulfur isotopes determined from sulfides including chalcopyrite sphalerite and pyrite demonstrate clear mixing trends between crustal and mantle derived components confirming a significant contribution of fluid produced from mantle derived magmas into the epithermal system like many mesozoic porphyry cu mo au deposits the coeval epithermal au ag te deposits in the region are genetically related to magmatism triggered by the subduction of the pacific oceanic plate beneath the eurasian continent at the time

improved identification of volcanic features using landsat 7 etm volcanic eruptions can present unpredictable hazards to populations living within regions containing potentially active volcanoes and for people traveling in jet aircraft that intersect with ash laden eruption clouds methods of monitoring volcanic activity include searching for variations in the thermal signal from active fumaroles lava domes lava lakes flows and other features over many active volcanoes in the western hemisphere low spatial resolution 4 km pixel weather satellite data acquired every 15 min are used to identify changes in eruptive activity but are of insufficient spatial resolution to map active volcanic features the enhanced thematic mapper plus etm on landsat 7 can be used to monitor active volcanoes at a higher spatial resolution 15 to 60 m pixels etm also offers improvements over its predecessor the thematic mapper of landsats 4 and 5 by way of a 15 m panchromatic band and higher spatial resolution 60 m pixel thermal infrared ir band with higher spatial resolution panchromatic data we are able to map lava flow fields trace very high temperature lava channels and at lascar volcano identify an arcuate feature associated with a collapsed crater floor a phenomenon that may precede explosive activity with improved spatial resolution in the thermal ir we are able to map the bifurcation and braiding of underground lava tubes at kilauea identifying tube locations and tracking their extension are important because for a given volumetric lava production effusion rate tube fed flows can extend a much greater distance than surface flows at both kilauea and etna we are able to use the thermal data to estimate effusion rates an important parameter for assessing how far a flow is likely to extend and therefore the hazard it poses an improved etm data collection and distribution system includes a well formulated and executed long term acquisition plan and less expensive data that is available much faster than previously possible

geology hydrothermal fluids h o s pb isotopes and rb sr geochronology of the daxintun orogenic gold deposit in heilongjiang province ne china abstract the newly discovered daxintun sb au deposit heilongjiang province ne china is located at the north eastern margin of the central asian orogenic belt and it is hosted by neoproterozoic to early cambrian two mica schist and marble the antimony bearing minerals include stibnite famatinite tetrahedrite boulangerite freibergite and minor andorite gold occurs largely as native gold microparticles 0 1 20 m with high fineness 974 983 accompanied by quartz stibnite calcite and pyrite fluid inclusions in ore bearing quartz and calcite phases mainly comprise liquid vapor and minor co2 bearing three phase types and the gas phases contain co2 ch4 and h2s the daxintun fluid inclusions homogenize at 111 8 353 4 c and are of low salinity 0 53 12 51 wt nacl equiv the 18osmow of the daxintun quartz falls into a wide range 4 2 16 9 yet the dsmow falls into a narrow range 108 0 to 87 3 suggesting that the ore forming fluids formed from metamorphic fluids that mixed with meteoric water the stibnite 34s ranges between 0 9 and 5 1 mean 2 8 the stibnite has 206pb 204pb of 18 234 18 306 207pb 204pb of 15 537 15 561 and 208pb 204pb of 38 103 38 227 implying a metamorphic fluid source the conditions of gold and antimony precipitation are comprised of neutral ph and fluid mixing with decreasing fs2 and fo2 zircon u pb dating of the fine grained daxintun granite yields a late jurassic age 154 0 2 0 ma and the daxintun diorite dike yields a weighted mean age of 122 1 1 3 ma stibnite rb sr dating suggests that the sb au mineralization has an age of approximately 152 8 2 4 ma the observed ore deposit geology as well as new data on the ore forming fluids h o s pb isotopes and rb sr geochronology suggest that the daxintun sb au deposit is best described as an orogenic type gold deposit that formed during subduction of the palaeo pacific and the mongolia okhotsk oceans during the late jurassic

analysis of active lava flows on kilauea volcano hawaii using sir c radar correlation measurements precise eruption rates of active pahoehoe lava flows on kilauea volcano hawaii have been determined using spaceborne radar data acquired by the space shuttle imaging radar c sir c a coastal site downslope from the pu9u o9o vent was imaged once per day on each of the four days of october 7 10 1994 day to day decorrelation due to resurfacing was determined by interferometric combination of the data at 15 m resolution over a wide area on successive days new lava resurfaced 335700 m 2 368775 m 2 and 356625 m 2 assuming an average pahoehoe flow thickness of 50 cm a mean effusion rate for this period is approximately 2 m 3 s the radar observations show persistent surface activity at each site rather than downslope migration of coherent lava flows

high resolution satellite and airborne thermal infrared imaging of precursory unrest and 2009 eruption at redoubt volcano alaska abstract a combination of satellite and airborne high resolution visible and thermal infrared tir image data detected and measured changes at redoubt volcano during the 2008 2009 unrest and eruption the tir sensors detected persistent elevated temperatures at summit ice melt holes as seismicity and gas emissions increased in late 2008 to march 2009 a phreatic explosion on 15 march was followed by more than 19 magmatic explosive events from 23 march to 4 april that produced high altitude ash clouds and large lahars two or three lava domes extruded and were destroyed between 23 march and 4 april after 4 april the eruption extruded a large lava dome that continued to grow until at least early july 2009

fumarole monitoring with a handheld infrared camera volcan de colima mexico 2006 2007 abstract this paper describes a methodology for the monitoring of fumarole temperatures at medium ranges 6 km using a handheld infrared camera wavelength range 8 13 5 m as a relationship between fumarole temperatures gas flux and volcanic activity has been demonstrated by a number of studies fumarole temperature data has a potential use as a monitoring tool volcan de colima is an andesitic stratovolcano with a 300 m diameter summit crater formed by the destruction of the 2004 lava dome by a series of explosions in 2005 between january 2006 and august 2007 sequences of thermal images were recorded from a viewpoint 6 km to the north during regular 24 48 hour monitoring excursions the temperatures of fumaroles on the crater rim and the ground surface on the volcano s flanks were measured a methodology was developed to remove data affected by clouds or volcanic water vapour based on rates of temperature change and scatter within the data for the remaining data it is demonstrated mathematically that at this range typical variations in atmospheric transmissivity will affect the apparent temperatures by 2 c while a 25 change in fumarole heat flux would change it by 5 10 c the mean night time apparent temperature of the fumaroles was calculated for each excursion and showed an irregular decline over the 19 month period subtracting the radiant heat flux of flank rocks from those of the fumaroles removes seasonal variations and gives the clearest view of trends in the fumarole heat flux a sharp drop in fumarole temperature during february 2007 coincided with the emergence of a lava dome in the crater the declining fumarole temperature is interpreted to reflect decreasing gas flux from the crater in line with a change in eruptive regime from frequent small ash rich explosions to slow effusion of lava

p t x conditions of hydrothermal fluids and precipitation mechanism of stibnite gold mineralization at the wiluna lode gold deposits western australia conventional and infrared microthermometric constraints the wiluna lode gold deposits are located in the archean wiluna greenstone belt in the northern sector of the norseman wiluna belt in the yilgarn craton of western australia they are hosted in subgreenschist facies meta basalts and controlled by the wiluna strike slip fault system and associated shear veins and breccias the 13 individual lode gold deposits have produced around 115 t au from 1901 to 1946 and 1986 to today historically they also produced 38 3 t as and 3 5 t sb gold formed in two stages stage 1 gold pyrite arsenopyrite is finely disseminated in the wallrock and breccia fragments whereas stage 2 gold stibnite is located in massive shear veins and breccia matrix as fracture fill and in banded colloform textured veins stibnite gold orebodies only occur in some of the deposits e g moonlight and northern part of the west lode and also display a restricted vertical extent being preserved only in the uppermost 200 m of stibnite bearing lodes petrographic conventional and infrared microthermometric and laser raman analysis on stibnite bearing quartz veins and breccias reveal that the antimony and gold rich hydrothermal fluid was of mixed h2o nacl co2 ch4 type microthermometric measurements reveal maximum homogenization temperatures of 340 c average 290 25 c and a wide range of salinities between 0 2 and 23 eq wt nacl aqueous carbonic fluid inclusions contain variable xco2 ch4 0 03 to 0 82 with the carbonic phase containing a maximum xch4 of 0 21 combined petrographic and microthermometric evidence suggests that the fluid inclusion properties reflect fluid immiscibility of a low salinity medium xco2 ch4 homogeneous parent fluid at about 290 c and pressures between 700 and 1 700 bar fluid immiscibility was triggered by cyclic pressure release during fault zone movement the decompression adiabatic cooling of the hydrothermal fluids shifted the ore fluid to lower temperatures significantly reduced the degree of stibnite undersaturation and caused stibnite to precipitate the deposition of stibnite reduced the ore fluid h2s concentration thereby destabilized gold bisulfide complexes in solution and caused gold precipitation locally this mechanism explains the intimate spatial association of stibnite and gold in quartz veins and breccias in the stibnite gold orebodies at wiluna

evolution of the mongol okhotsk ocean as constrained by new palaeomagnetic data from the mongol okhotsk suture zone siberia summary this paper presents new data from palaeomagnetic investigations on the upper palaeozoic and mesozoic geological units from the siberian platform and the mongol okhotsk suture zone within the southern portion of the mongol okhotsk suture we collected palaeomagnetic samples from the late permian belektuy formation borzya region 50 7un 116 9ue and the middle late jurassic shadaron formation unda daya 51 5un 117 5ue we sampled the late permian alentuy formation khilok region 50 8un 107 2ue the early to middle jurassic irkutsk sedimentary basin isb 52 0un 104 0ue the late jurassic badin formation mogzon region 51 8un 112 0ue and the early cretaceous gusinoozesk formation gusinoe lake region 51 2un 106 5ue additionally in the northern region of the mongol okhotsk suture apart from the results of the isb and gusinoozersk formations which show very large ellipses of confidence and might be the present day geomagnetic field overprint our results allow us to constrain the evolution of the mongol okhotsk ocean palaeomagnetically from the late permian to the middle late jurassic they confirm that this large permian ocean closed during the jurassic ending up in the late jurassic or the beginning of the cretaceous in the eastern end of the suture zone as suspected on geological grounds however although geological data suggest a middle jurassic closure of the mongol okhotsk ocean in the west trans baikal region our data show evidence of a still large palaeolatitude difference between the amuria and siberia blocks this is interpreted as a result of the quite fast closure of the ocean after the middle jurassic finally our new palaeomagnetic results exhibit very large tectonic rotations around local vertical axes which we interpret as probably arising both from collision processes and from a left lateral shear movement along the suture zone due to the eastward extrusion of mongolia under the effect of the collision of india into asia

the evolution of an active silicic lava flow field an etm perspective an active dacitic lava flow began advancing down the south flank of the caliente dome unit santiaguito volcano guatemala during july 1999 by january 2002 continued activity had built a 1 km2 66 106 m3 flow field using a time series of landsat 7 etm images and field observations the evolution and characteristics of this flow field are described throughout the period of emplacement flow front advance rates have been extremely slow 2 13 m day 1 consistent with a viscosity of 109 1010 pa s however extremely efficient thermal insulation has allowed flow fronts to extend up to 3 75 km from the vent in spite of extrusion rates of just 0 5 1 6 m3 s 1 surface temperatures along most of the flow are less than 75 c and typically 40 c such surface temperatures result in extremely low rates of heat loss and thus core cooling of just 0 03 0 09 c h 1 or 0 01 0 12 c m 1 the flow field itself clearly displays the same systematic spatial variations in structure and morphology as described by lipman and banks prof pap geol surv u s 1350 1987 1527 for a basaltic a a flow where a stable and then transitional channel zone feeds a distal area of dispersed flow the stable channel dominates the proximal and medial sections of the flow field and comprises a 90 375 m wide channel flanked by levees that are up to 117 m high a marked increase in the flow area and thickness occurred between january 2001 and january 2002 and was coincident with an increase in the extrusion rate from 0 5 0 7 to 1 2 1 6 m3 s 1 however this increase in extrusion rate did not bring an increase in flow lengths indicating that the flow may have reached its cooling limited length around january 2001

surface temperature measurements of active lava flows on kilauea volcano hawai i systematic hand held radiometer measurements of lava surface temperatures in active flows and tubes on kilauea volcano hawai i reveal complexities that cannot be resolved in remotely sensed data from aircraft or satellites using portable infrared minolta land cyclops radiometers we measured surface temperatures of flows at various distances from their sources and investigated cooling rates and the development of crust our measurements suggest that the upper surface of these lava flows can be split into a minimum of four thermal components core 1050 c visco elastic skin 750 900 c rigid solid crust 750 c and flow margins 175 c for the a a flows investigated a cool rigid crust characteristically developed in the central part of channels within 30 m of the source vent and incandescent lava was exposed in the marginal shear zones of channels this affects the heat loss and morphology of lava in active channels our investigations of temperature distributions on pahoehoe flow fields reveal temperature anomalies of up to 150 c above active tubes and tumuli

the changing morphology of an open lava channel on mt etna an open channel lava flow on mt etna sicily was observed during may 30 31 2001 data collected using a forward looking infrared flir thermal camera and a minolta land cyclops 300 thermal infrared thermometer showed that the bulk volume flux of lava flowing in the channel varied greatly over time cyclic changes in the channel s volumetric flow rate occurred over several hours with cycle durations of 113 190 min and discharges peaking at 0 7 m3 s 1 and waning to 0 1 m3 s 1 each cycle was characterized by a relatively short high volume flux phase during which a pulse of lava with a well defined flow front would propagate down channel followed by a period of waning flow during which volume flux lowered pulses involved lava moving at relatively high velocities up to 0 29 m s 1 and were related to some change in the flow conditions occurring up channel possibly at the vent they implied either a change in the dense rock effusion rate at the source vent and or cyclic variation in the vesicle content of the lava changing its bulk volume flux pulses would generally overspill the channel to emplace p hoehoe overflows during periods of waning flow velocities fell to 0 05 m s 1 blockages forming during such phases caused lava to back up occasionally backup resulted in overflows of slow moving a that would advance a few tens of meters down the levee flank compound levees were thus a symptom of unsteady flow where overflow levees were emplaced as relatively fast moving p hoehoe sheets during pulses and as slow moving a units during backup small localized fluctuations in channel volume flux also occurred on timescales of minutes volumes of lava backed up behind blockages that formed at constrictions in the channel blockage collapse and or enhanced flow under around the blockage would then feed short lived wave like down channel surges real fluctuations in channel volume flux due to pulses and surges can lead to significant errors in effusion rate calculations

on the retrieval of lava flow surface temperatures from infrared satellite data the dual band method has been widely used as the basis for determining lava surface temperatures from infrared satellite data the method is based on the assumption that such surfaces can be described in terms of two end member thermal components hot cracks within a thermally homogeneous crust the recent launch of the first orbiting hyperspectral imaging system hyperion on board the national aeronautics and space administration earth observing 1 eo 1 satellite heralds a new era of space based hy perspectral data collection that will allow more detailed models of lava flow surface temperatures to be developed and parameterized to this end we have analyzed thermal images of active pahoehoe lava flows collected on kilauea volcano hawaii by using a forward looking infrared flir 595 pm thermacam in order to assess the number of thermal components required to characterize the surface temperatures of active lava flow surfaces the flir images show that an active lava flow surface comprises a contin uum of temperatures that define distinctive temperature distribu tions numerical model results reveal that the two component dual band method fails to resolve any of the major properties of the temperature distributions contained in these data i e mode skew range or dispersion however modeling five to seven thermal components allows all significant properties of the subpixel tem perature distributions contained within the flir images to be de termined thus although the hyperspectral data provided by the eo 1 hyperion yield as many as 66 wavebands in the 0 5 2 5 mm atmospheric window useable data in 9 13 of these should be suf ficient to perform accurate temperature characterization of active lava flow surfaces from space

a carbonaceous sedimentary source rock model for carlin type and orogenic gold deposits this paper presents evidence and arguments that carbonaceous sedimentary rocks were a source for au and as in sediment hosted orogenic and carlin type gold deposits and develops a corresponding genetic model in this two stage basin scale model gold and arsenic are introduced early into black shale and turbidite basins during sedimentation and diagenesis stage 1 and concentrated to ore grades by later hydrothermal structural or magmatic processes stage 2 in reduced continental margin basin settings organic matter sedimented under anoxic to euxinic conditions immobilizes and concentrates gold arsenic and a range of trace elements particularly v ni se ag zn mo cu u present in marine bottom waters into fine grained black mudstone and siltstone of slope and basin facies during early diagenesis gold and certain other trace elements ni se te ag mo cu pge are preferentially partitioned into arsenian pyrite that grows in the muds these processes produce regionally extensive black shale and turbidite sequences enriched in syngenetic gold and arsenic commonly from 5 to 100 ppb au and 10 to 200 ppm as rare organic and sulfide rich metalliferous black shales may contain up to 1 to 2 ppm au and over 1 000 ppm as present as refractory gold in arsenian pyrite and nanoparticles of free gold during late diagenesis and early metamorphism stage 2 the diagenetic arsenian pyrite is recrystallized to form coarser grained pyrite generations and the organic matter is cooked to bitumen under higher grade metamorphism lower greenschist facies and above arsenian pyrite in carbonaceous shales is converted to pyrrhotite these processes release gold arsenic sulfur and other elements sb te cu zn mo bi tl and pb from the source rocks to become concentrated by hydrothermal processes locally to produce gold ores in structural sites such as fold hinge zones shear or breccia zones within or above the black shale sequence la icp ms analyses of diagenetic pyrite in carbonaceous sediments both associated and not associated with gold deposits suggests that invisible gold contents of greater than 250 ppb in diagenetic pyrite are indicative of carbonaceous shale source rocks with the potential to produce economic gold deposits application of this sedimentary source rock model enables a systematic exploration approach for sediment hosted gold deposits based on the distribution composition and structure of carbonaceous shale sequences and their contained diagenetic pyrite

p t fluid deformation regime of the ediacaran serra do cavalo magro orogenic gold deposit ribeira belt brazil abstract the serra do cavalo magro orogenic gold deposit is located in the southern ribeira belt brazil gold quartz veins are hosted in calymmian 1500 1450 ma metasedimentary and metabasic rocks and ediacaran 610 600 ma granitic rocks geochronological data available in previous literature and structural petrological relationships with host rocks and shear zones indicate that the gold mineralization was formed within 580 540 ma during the late stage evolution of the brasiliano pan african orogeny related with gondwana supercontinent assembly petrological modeling indicates peak metamorphic conditions from 560 c and 7 kbar chlorite biotite phyllite to 625 c and 6 8 kbar garnet biotite phyllite recorded in immediate host rocks gold mineralization occurs in quartz shear and extensional veins structurally controlled by ne trending second and third order sinistral transcurrent shear zones the nnw trending subvertical and subhorizontal extensional veins are oriented 55 85 in relation to the fault planes indicating the shear zones were severely misoriented to frictional reactivation deformation within the shear zones was accommodated by bulging recrystallization of quartz aggregates while feldspar aggregates from the granitic protolith underwent cataclastic flow or were replaced by sericite epidote producing phyllonites gold precipitated during stages of vein deformation within microfractures in shear and extensional veins with quartz previously subjected to bulging recrystallization metamorphic ore bearing fluids are recorded in distinct assemblages of low to moderate salinities 1 18 wt nacleq h2o nacl cacl2 and h2o co2 n2 nacl cacl2 fluid inclusions and co2 n2 inclusions microthermometric data indicate entrapment conditions of 250 350 c and 0 3 2 3 kbar recording hydrostatic to supralithostatic fluid pressures in post peak metamorphic stages sharp fluid pressure fluctuations 0 4 1 6 kbar resulted from earthquake rupture events and the fault valve behavior induced circulation of fluids from distinct sources with limited partial fluid mixing favoring the gold transportation and precipitation

the influence of wind on the estimation of lava effusion rate from thermal remote sensing effusion rate is a key parameter to model lava flow advance and associated risks estimation of effusion rate from thermal remote sensing using satellite data has matured to the point where it can be an operational monitoring tool notably for volcanoes without a ground observatory however robust physical models as required for quantitative interpretations have not yet been adequately developed the current and widely used method relates the satellite measured radiated power to the flow effusion rate through the lava area with an empirical fit that assumes a low surface cooling efficiency here we use novel fluid dynamic laboratory experiments and viscous flow theory to show that assuming low convective cooling at the surface of the flow leads to a systematic underestimation of the effusion rate this result obtained for the case of a hot isoviscous gravity current which cools as it flows relies only on the respective efficiency of convection and radiation at the flow surface and is independent of the details of the internal flow model applying this model to lava flows cooling under classical wind conditions we find that the model compares well to data acquired on basaltic eruptions within the error bars corresponding to the uncertainties on natural wind conditions hence the thermal proxy deduced from the isoviscous model does not seem to require an additional fitting parameter accounting for internal flow processes such as crystallization the predictions of the model are not correct however for thick lava flows such as highly viscous domes because a thermal steady state is probably not reached for these flows furthermore in the case of very large basaltic flows extra cooling is expected due to self induced convection currents the increased efficiency of surface cooling for these large eruptions must be taken into account to avoid a gross and dangerously misleading underestimate of the effusion rate

infrared monitoring of volcanoes by satellite sensors on future satellite platforms will be used routinely for volcano monitoring with infrared channels offering the potential to detect and measure temperatures of features such as lava bodies and fumarole fields this is possible even though the surface temperature distributions associated with such phenomena are typically inhomogeneous at the pixel scale so long as simplifying assumptions can be made to test the applicability of the technique we have carried out field studies of a range of volcanic thermal manifestations using portable infrared thermometers rock surface temperatures around fumarolic vents exhibit greater stability with time than those associated with actively degassing lava bodies but in both cases volcanogenic fumes can significantly attenuate the emitted infrared radiation the scale of the temporal variability at a given wavelength dictates the quantitative value of isolated satellite 9snapshots9 if more spectral channels in the infrared were available on remote sensing platforms then more components of the surface temperature distribution could be extracted from the data imaging spectrometry offers the greatest flexibility although data processing including correction for atmospheric effects would present difficulties

factors affecting the accuracy of thermal imaging cameras in volcanology volcano observatories and researchers are recognizing the potential usefulness of thermal imaging cameras both before and during volcanic eruptions obvious applications include measurements of the surface temperatures of active lava domes and lava flows to determine the location of the most active parts of these potentially hazardous features if appropriate precautions are taken the new generation of thermal imaging cameras can be used to extract quantitative as well as qualitative information on volcanic activity for example they can be used to measure the temperature of lava on eruption and to reveal how the crust cools during flow emplacement this is important for the validation of lava flow models to ensure that meaningful temperatures are collected thermal imaging data must be corrected for instrumental errors emissivity of the surface being imaged atmospheric attenuation viewing angle and surface roughness controlled laboratory experiments have been undertaken to determine the emissivity of smooth and rough samples and the effects of viewing angle and to quantify the errors measured emissivities range from 0 973 0 002 for smooth samples of basalt and 0 984 0 004 for rough samples errors in emissivity corrected temperatures are within 15 c for lava at 1100 c variations from individual sensor receptors which provide individual pixel temperature data were found to be 0 6 and instrumental errors of the cameras used were 0 1 apparent temperatures were found to vary by less than the instrumental error for viewing angles up to 30 degrees from normal to lava and thereafter increased by 1 c per degree by increasing the apparent viewing distance of a small vent on mount etna from 1 5 to 30 m the maximum temperature is shown to decrease by 53 c due to integrated averaging of radiance over increased pixel areas at a viewing distance of 250 m the maximum temperature decreased by 200 c with a further 75 c decrease due to atmospheric attenuation for a relative humidity of 50 however errors in relative humidity measurements can lead to atmospheric attenuation correction inaccuracies up to 200 c at viewing distances of 1 km we show how temperatures measured using thermal imaging cameras can be corrected to give improved estimates of temperature distributions on the surface of active lava flows

the sources of ore forming material in the low sulfidation epithermal wulaga gold deposit ne china constraints from s pb isotopes and ree pattern abstract the wulaga gold deposit located in heilongjiang province ne china is a subvolcanic rock hosted low sulfidation epithermal gold deposit and has an au reserve of about 84 tons the gold mineralization occurs in a crypto explosive breccia and is spatially and temporally associated with an early cretaceous granodioritic porphyry three individual stages of mineralization have been identified in the wulaga gold deposit an early white quartz euhedral vein stage a fine grained pyrite marcasite stibnite chalcedony stage and a late calcite pyrite stage the sulfur isotopic values of sulfide minerals vary in a wide range from 4 to 4 9 but are concentrated in the range of 3 to 0 implying that sulfur in the hydrothermal fluids was derived from magmatic volatiles lead isotopic results of the granodioritic porphyry 206pb 204pb 18 341 18 395 207pb 204pb 15 507 15 523 208pb 204pb 38 174 38 251 and sulfide minerals 206pb 204pb 18 172 18 378 207pb 204pb 15 536 15 600 208pb 204pb 38 172 38 339 are comparatively consistent and clustered together between the orogenic and upper mantle lines indicating the lead in the ores is closely related to the parent magma of the granodioritic porphyry the ree patterns of fluid inclusions trapped in sulfides are similar to those of the granodioritic porphyry which confirms the magmatic origin of the ree in the hydrothermal fluids the characteristics of s and pb isotopes and ree suggest that the ore forming materials of the wulaga gold deposit are partly magmatic in origin and related to a high level hydrous granodioritic magma

modelling of thermo mechanical effects in a rock quarry wall induced by near surface temperature fluctuations abstract mechanical response of rock masses to the periodical fluctuation of surface temperatures is a relevant topic to be focused on for the comprehension of short to long term stability of rock slopes continuously stressed by slight yet periodical actions to better understand how preparatory factors can lead rock masses toward failure thermal and strain monitoring activities are ongoing in a selected quarry wall where an experimental test site was implemented on a jointed rock block the role of pervasive joints in perturbing the heating cooling process of the rock mass and their related effects was already output by direct and remote monitoring for these purposes fdm numerical modelling was focused on the comprehension and simulation of induced mechanical effects due to cyclical thermal forcings over a simplified 2d half space therefore the role of rock mass joints on both heat propagation and resulting thermo mechanical effects was analysed basing on monitoring data field experiments and numerical modelling numerical results output the role of periodic daily annual and compound thermal input in inducing irreversible deformation along joints under different rock mass jointing configuration as a function of the intrinsic period of thermal input and joint attitude temperature distribution across joints was also analysed as a possible constraining effect for time and space distribution of yielding a sensitivity analysis of heat propagation conditions was performed in order to infer the role of joint sets on induced thermo mechanical strains at the rock block scale a non negligible influence on surficial as well as deeper portions of the rock mass was observed highlighting how near surface temperature fluctuations can drive the long term evolution of rock block conditions towards failure

geology of the sandaowanzi telluride gold deposit of the northern great xing an range ne china geochronology and tectonic controls abstract the sandaowanzi gold telluride deposit is a new discovery with dominance in gold tellurides in northeastern china the deposit is hosted in quartz veins intruding sub alkaline volcanic rocks there are two types of gold telluride ores in the sandaowanzi ore deposit i e the vein ores and the disseminated ores calaverite krennerite sylvanite petzite empressite hessite and stuetzite are the dominant au ag bearing minerals either in vein ores or in disseminated ores minor amount of other tellurides e g coloradoite altaite and sulfides e g pyrite sphalerite galena chalcopyrite and chalcocite mostly occur in the disseminated ores the gold bearing quartz veins crosscut volcanic host rocks which are dated at 135 3 124 7 ma by la icp ms u pb zircon method the latter unconformably overly a monzogranite dated as 181 6 ma diabase dikes dated at 116 6 ma intrude the gold bearing quartz veins the age data thereby bracket the timing of gold mineralization between 125 3 and 116 6 ma these geochronologic data are consistent with field relations regional comparison reveals that the widespread volcanism in the great xing an range is a product of the subduction of the izanagi plate beneath the eurasian plate gold telluride mineralization was contemporaneous with regional extension and magmatism as the subducting izanagi plate rolled back

late jurassic early cretaceous closure of the mongol okhotsk ocean demonstrated by new mesozoic palaeomagnetic results from the trans baikal area se siberia summary we present new palaeomagnetic results from the transba ikal area se siberia from the mongol okhotsk suture zone the boundary between the amuria and siberia blocks in order to better constrain the time of closure of the mongol okhotsk ocean in the mesozoic we col lected 532 rock samples at 68 sites in six localities of basalts trachy basalts and andesites from both sides of the mongol okhotsk suture at unda river j 3 51 7 n 117 4 e kremljevka peak k1 51 8 n 117 5 e and torey lakes k 1 50 1 n 115 9 e on the southern side of the suture and at monostoy river j 1 51 1 n 106 8 e ingoda river k 1 51 2 n 112 2 e and bichura town k 1 50 6 n 107 6 e on the northern side progressive thermal demagnetization enabled us to resolve low ltc and high htc temperature components of magnetization at most sites jurassic palaeopoles computed from the htcs show a large discrepancy with respect to the apparent polar wander path of eurasia which we interpret in terms of 1700 2700 km of post late jurassic northward movement of amuria with respect to siberia although ge ological data suggest a middle jurassic closure of the mongol okhotsk ocean in the west trans baikal region our data give evidence of a large remaining palaeolatitude difference between the amuria and siberia blocks in contrast early cretaceous sites cluster remarkably well along a small circle which is centred on the average site location this implies the absence of post early cretaceous northward motion of amuria relative to siberia and demonstrates the pre early cretaceous closure of the mongol okhotsk ocean finally we interpret the very large tectonic rotations about local vertical axes evidenced by the small circle distribution of poles as arising both from collision processes and from left lateral shear movement along the suture zone due to the eastward extrusion of amuria under the effect of the collision of india into asia

volumetric characteristics of lava flows from interferometric radar and multispectral satellite data the 1995 fernandina and 1998 cerro azul eruptions in the western galapagos we have used a suite of remotely sensed data numerical lava flow modeling and field observations to determine quantitative characteristics of the 1995 fernandina and 1998 cerro azul eruptions in the western galapagos islands flank lava flow areas volumes instantaneous effusion rates and average effusion rates were all determined for these two eruptions for which only limited syn eruptive field observations are available using data from spot topsar ers 1 and ers 2 we determined that the 1995 fernandina flow covers a subaerial area of 6 5 106 m2 and has a subaerial dense rock equivalent dre volume of 42 106 m3 field observations atsr satellite data and the flowgo numerical model allow us to determine that the effusion rate declined exponentially from a high of 60 200 m3 s 1 during the first few hours to 5 m3 s 1 prior to ceasing after 73 days with a mean effusion rate of 4 16 m3 s 1 integrating the atsr derived exponentially declining effusion rate over the eruption duration produces a total subaerial submarine dre volume of between 27 and 100 106 m3 the range in values being due to differing assumptions about heat loss characteristics only values in the higher part of this range are consistent with the independently derived subaerial volume using spot topsar ers 1 and ers 2 data we determine that the 1998 cerro azul flow is 16 km long covers 16 km2 and has a dre volume of 54 106 m3 flowgo produces at vent velocity and effusion rate values of 11 m s 1 and 600 m3 s 1 respectively the velocity value agrees well with the 12 m s 1 estimated in the field the mean effusion rate total dre volume duration was 7 47 m3 s 1 dike dimensions fissure lengths and pressure gradients along the conduit based on magma chamber depth estimates of 3 5 km produce mean effusion rates for the two eruptions that range over nearly four orders of magnitude the range being due to uncertainty in the magma viscosity dike dimensions and pressure gradient between magma chamber and vent although somewhat consistent with mean effusion rates from other techniques their wide range makes them less useful the exponentially declining effusion rates during both eruptions are consistent with release of elastic strain being the driving mechanism of the eruptions our results provide independent input parameters for previously published theoretical relationships between magma chamber pressurization and eruption rates that constrain chamber volumes and increases in volume prior to eruption as well as time constants of exponential decay during the eruption the results and theoretical relationships combine to indicate that at both volcanoes probably 25 30 of the volumetric increase in the magma chamber erupted as lava onto the surface in both eruptions the lava flow volumes are less than 1 of the magma chamber volume

volcano monitoring using short wavelength infrared data from satellites data from remote sensing satellites operating in the short wavelength infrared can be used to measure temperatures of about 150 c and above the gain settings of the landsat thematic mapper tm sensors are such that to record pixel integrated temperatures from 150 c to over 1000 c requires the use of several spectral bands if the radiant source occupies less than a whole pixel as is the case for fumaroles or a crusted lava surface with incandescent cracks then the pixel integrated temperature is less than the actual surface temperature of the hot areas and appears to be different at each wavelength by determining pixel integrated temperature in two spectral bands we can estimate both the temperature and size of hot areas which occupy less than a complete pixel in some cases our observations provide the only available data on the state of activity of a particular volcano in others they support and refine field observations our landsat tm data reveal otherwise unobserved precursor and subsequent activity related to the september 1986 eruption of lascar volcano chile and supplement other data on the march 1986 eruption of augustine volcano alaska they also indicate the continued presence of lava lakes at erta ale ethiopia in the absence of any ground based observations and document minor eruptive activity at mount erebus antarctica landsat multispectral scanner data have been used to measure the variation in temperature along a lava flow on sierra negra galapagos islands which occurred in 1979

a review of the genesis geochronology and geological significance of hydrothermal copper and associated metals deposits in the great xing an range ne china abstract the great xing an range located in the eastern mongolia hinggan orogenic belt ne china hosts numerous endogenous base and precious metal mineral deposits the hydrothermal copper and associated metals deposits in this area can be divided into three genetic types based on their geology and geochronology porphyry cu mo high sulfidation cu ag and cu sn epithermal and cu fe skarn all of these mineral deposits barring the cu sm epithermal deposits are closely related to high k calc alkaline i type granitic magmatism the eastern part of the area hosts porphyry copper deposits that generally formed around 180 170 ma with a few deposits formed at 485 ma whereas high sulfidation epithermal copper silver deposits in the central great xing an range formed at 245 ma the west of the study area hosts high sulfidation epithermal cu sn deposits that formed at 150 135 ma and are related to a type granites skarn deposits are associated with the epithermal and porphyry deposits described above and formed at 180 160 and 150 135 ma the geodynamic setting of the region during these mineralizing events is consistent with early paleozoic collision between the xing an massif and the songnen terrane late permian collision between the north china craton ncc and the heilongjiang plate middle jurassic collision between the siberian plate and the ncc epicontinental aggradational belt and crustal extension and thinning during an early cretaceous collisional orogenic event this indicates that the mineral deposits formed in an intracontinental transitional orogenic or post orogenic extensional tectonic setting

monitoring eruptive activity at mount st helens with tir image data 1 thermal infrared tir data from the master airborne imaging spectrometer were acquired over mount st helens in sept and oct 2004 before and after the onset of recent eruptive activity pre eruption data showed no measurable increase in surface temperatures before the first phreatic eruption on oct 1 master data acquired during the initial eruptive episode on oct 14 showed maximum temperatures of 330 c and tir data acquired concurrently from a forward looking infrared flir camera showed maximum temperatures 675 c in narrow 1 m fractures of molten rock on a new resurgent dome master and flir thermal flux calculations indicated a radiative cooling rate of 714 j m2 s over the new dome corresponding to a radiant power of 24 mw master data indicated the new dome was dacitic in composition and digital elevation data derived from lidar acquired concurrently with master showed that the dome growth correlated with the areas of elevated temperatures low so2 concentrations in the plume combined with sub optimal viewing conditions prohibited quantitative measurement of plume so2 the results demonstrate that airborne tir data can provide information on the temperature of both the surface and plume and the composition of new lava during eruptive episodes given sufficient resources the airborne instrumentation could be deployed rapidly to a newly awakening volcano and provide a means for remote volcano monitoring

thermal imaging and analysis of short lived vulcanian explosions at volcan de colima mexico abstract vulcanian explosions present a major hazard at many active volcanoes but they also provide useful insights into the underlying behaviour of the volcanic system and therefore require close monitoring thermal infrared cameras are an effective tool for imaging vulcanian explosion plumes since they capture detailed temperature information and can reveal the internal dynamics of the plume forming explosions high spatial resolution thermal images of 200 small to moderate sized vulcanian explosions from the summit crater of volcan de colima mexico recorded between 2006 and 2011 were analysed to distinguish different event types and develop an explosion classification scheme explosions display a broad spectrum of sizes and characteristics ranging between two typical end members large impulsive events producing rapidly ascending explosion plumes up to heights of 600 1600 m above the crater rim and small diffusive events with plumes restricted to heights 1 to 29 m s 1 a time series of thermal imagery throughout the period 2006 2011 reveals a weak relationship between apparent plume temperatures and lava dome extrusion with the highest explosion temperatures coinciding with the onset of dome growth in early 2007 temporal variations in the source locations of explosions across the summit crater are also identified and appear to show a close relationship to the patterns of lava dome growth and thermal evolution with explosion source locations associated with the highest temperature thermal features

tectonic implications of new zircon u pb ages for the xinghuadukou complex erguna massif northern great xing an range ne china abstract the nature and the timing of formation of the xinghuadukou complex of ne china are important to further our understanding of the precambrian geological evolution of the erguna massif and the eastern segment of the central asian orogenic belt caob here we present the results of zircon u pb dating of a metavolcanic rock and 11 granitoid basement samples collected from the complex we use these data to determine the age and tectonic origin of the complex and to examine the linkages between this complex and the surrounding tectonic domains and older cratonic areas igneous zircons from the metavolcanic rock yield a magmatic age of 850 ma indicating that the supracrustal rocks that represent the original xinghuadukou group formed during the neoproterozoic petrological data and new zircon u pb ages for these samples enabled the identification of multiple stages of granitoid magmatism within different sections of the xinghuadukou group indicating that this group which was originally thought to have formed contemporaneously actually records the emplacement of granitoids at 957 786 479 418 265 and 209 192 ma this result indicates that the xinghuadukou complex records multiple stages of magmatism and contains various neoproterozoic supracrustal components combining the new age data with regional geological data we propose that the erguna massif should be considered part of the mongol domain as it has a close affinity to other blocks that formed part of this domain during the neoproterozoic these data suggest that all of the complexes and terranes within the mongol domain belong to the caob and were finally accreted to the southern margin of the siberian craton in the early paleozoic

the initial cooling of pahoehoe flow lobes in this paper we describe a new thermal model for the initial cooling of pahoehoe lava flows the accurate modeling of this initial cooling is important for understanding the formation of the distinctive surface textures on pahoehoe lava flows as well as being the first step in modeling such key pahoehoe emplacement processes as lava flow inflation and lava tube formation this model is constructed from the physical phenomena observed to control the initial cooling of pahoehoe flows and is not an empirical fit to field data we find that the only significant processes are a heat loss by thermal radiation b heat loss by atmospheric convection c heat transport within the flow by conduction with temperature and porosity dependent thermal properties and d the release of latent heat during crystallization the numerical model is better able to reproduce field measurements made in hawai i between 1989 and 1993 than other published thermal models by adjusting one parameter at a time the effect of each of the input parameters on the cooling rate was determined we show that a the surfaces of porous flows cool more quickly than the surfaces of dense flows b the surface cooling is very sensitive to the efficiency of atmospheric convective cooling and c changes in the glass forming tendency of the lava may have observable petrographic and thermal signatures these model results provide a quantitative explanation for the recently observed relationship between the surface cooling rate of pahoehoe lobes and the porosity of those lobes jones 1992 1993 the predicted sensitivity of cooling to atmospheric convection suggests a simple field experiment for verification and the model provides a tool to begin studies of the dynamic crystallization of real lavas future versions of the model can also be made applicable to extraterrestrial submarine silicic and pyroclastic flows

the gaosongshan epithermal gold deposit in the lesser hinggan range of the heilongjiang province ne china implications for early cretaceous mineralization abstract the newly discovered and large ca 99 ma gaosongshan gold deposit is located in the lesser hinggan or xinggan range to the west of the jiamusi massif the deposit is located at the border of the great hinggan range mongolian orogen with the circum pacific tectonic belt and has a resource of 22 t 6 3 g t au gaosongshan is classified as an adularia sericite epithermal deposit associated with the large tensional shaqihe fault and has a low sulfide content with a high concentration of gold hosted by pure chalcedonic quartz which makes the deposit both unique and economically important in the area early cretaceous volcanic rocks host the deposit as well as other gold deposits in the region the mineralization at gaosongshan includes au ag mo sb as pb and hg stable isotope studies of fluid inclusions associated with the mineralization suggest that the mineralizing fluid had a meteoric origin d v smow 129 to 111 18 o fluid 7 9 to 13 8 fluid inclusion thermography indicates that the mineralized fluid was between 150 and 310 c and had a low salinity 0 7 3 71 wt nacl low density 0 48 0 94 g cm 3 shallow metallogenic depth 430 1270 m and a large amount of reducing gaseous components ch 4 c 2 h 6 co n 2 and co 2 the presence of large quantities of flaky quartz adularia gas rich fluid inclusions low sulfide minerals and pure gold bearing chalcedonic quartz suggests that fluid boiling was the principal mechanism for the gold precipitation sulfur isotopic data 34 s 2 4 to 2 9 indicate a deep magmatic origin for the mineralization and the pb isotopes 206 pb 204 pb 18 14 18 46 207 pb 204 pb 15 51 15 57 208 pb 204 pb 38 01 38 40 also indicate that the metallogenic source of the deposit contained a significant mantle component the mineralizing fluid interacted with a late paleozoic ca 260 253 ma substrate and ca 141 91 ma volcanic host rocks the geological and geochemical characteristics of the deposit and the tuanjiegou dongan sandaowanzi and other large gold deposits represent an early cretaceous 114 80 ma epithermal mineralizing events in the lesser hinggan range the belt is controlled by the volcanic sunwu jiayin basin formed in a back arc extensional setting along an active continental margin in east china and the gold deposits in the belt have the same genesis as porphyritic au cu deposits along the continental margin in eastern jilin and heilongjiang provinces it is here proposed that the mineralization in both regions is related to the subduction of the paleo pacific plate

geodynamics of the western part of the mongolia okhotsk collisional belt trans baikal region russia and mongolia abstract after the western edge of the mongolian microcontinent joined the siberian continent in the region of central mongolia in the earliest permian these two continental blocks remained turned at an angle of about 120 with respect to each other and separated on greater extent of their present day boundary by an enormous gulf of the paleopacific called the mongolia okhotsk ocean closure of this ocean at the early middle jurassic boundary led to the complete collision of siberia and mongolia which by then had already become part of the mongolia north china continent this main collisional episode which lasted through the middle and late jurassic involved thrusting folding and magmatism and produced the mongolia okhotsk belt the onon island arc which was located in the mongolia okhotsk ocean was squeezed between the two major continents inasmuch as the third element the island arc was involved in the collision it is reasonable to distinguish two branches of the mongolia okhotsk suture these branches control the spatial distribution of gold mineralization in the trans baikal region on the southeastern periphery of siberia the crust thickened considerably after the collision and a plateau like uplift formed in the early cretaceous when compression ceased the collisional uplift collapsed and the thrusts were transformed into low angle normal faults the motions on which were responsible for the formation of rift basins and exhumation of metamorphic core complexes

isotope systematics and fluid inclusion studies of the qiyugou breccia pipe hosted gold deposit qinling orogen henan province china implications for ore genesis abstract the qiyugou gold deposits henan province are hosted in breccia pipes within the xiong er terrane qinling orogen on the southern margin of the north china craton in these deposits three paragenetic assemblages have been recognized an early k feldspar epidote quartz pyrite a middle quartz polymetallic sulfide and a late quartz carbonate adularia in this paper we review and interpret fluid inclusion and stable and radiogenic isotopic data of host rocks and ores fluid inclusions in quartz and calcite include water rich co 2 rich and daughter crystal bearing the co 2 rich and daughter mineral bearing fluid inclusions are common in the early stage quartz and absent in the late stage quartz and calcite which only contain water rich fluid inclusions accordingly the early stage ore fluids are magmatic in origin and characterized by high temperature 350 c high salinity 30 wt nacl equiv and are co 2 rich fluid boiling in the middle ore stage resulted in co 2 release decreasing oxygen fugacity and rapid precipitation of ore materials the late stage fluids have low temperature low salinity are co 2 poor and lack daughter minerals these fluids are probably sourced from meteoric water h o c isotope systematics confirm that the ore fluid system evolved from magmatic to meteoric the carbon and lead isotope ratios indicate that the meso neoproterozoic sequence south of the xiong er terrane was the likely source of the ore forming materials the qiyugou breccia pipes and their associated gold ores were emplaced during an extensional regime following a transition from collision to rifting tectonics linked to collision and subduction of the yangtze plate beneath the north china craton geochronological studies show that mesozoic magmatism in the region occurred between the triassic and cretaceous the triassic to jurassic magmas were mostly derived from partial melting of ancient crust whereas the cretaceous magmas show juvenile signatures indicating mantle derived components processes of fragmentation of lithospheric roots crustal and lithospheric thinning extension and rifting were probably associated with the subducting pacific izanagi plate these crust mantle geodynamic processes were responsible for the development of anorogenic granitic melts that interacted with the meso neoproterozoic volatile rich sedimentary successions producing a flow of gas rich hydrothermal fluids that resulted in the emplacement of the qiyugou auriferous breccia pipes we conclude that the qiyugou gold deposits are intrusion related explosive breccia pipe type that evolved from hypothermal through mesothermal to epithermal

thermal precursors in satellite images of the 1999 eruption of shishaldin volcano shishaldin volcano unimak island alaska began showing signs of thermal unrest in satellite images on 9 february 1999 a thermal anomaly and small steam plume were detected at the summit of the volcano in short wave thermal infrared avhrr advanced very high resolution radiometer satellite data this was followed by over 2 months of changes in the observed thermal character of the volcano initially the thermal anomaly was only visible when the satellite passed nearly directly over the volcano suggesting a hot source deep in the central crater obscured from more oblique satellite passes the zenith angle needed to see the anomaly increased with time presumably as the thermal source rose within the conduit based on this change an ascent rate of ca 14 m per day for the thermal source was estimated until it reached the summit on around 21 march it is thought that strombolian activity began around this time the precursory activity culminated in a sub plinian eruption on 19 april ejecting ash to over 45 000 ft 13 700 m the thermal energy output through the precursory period was calculated based on geometric constraints unique to shishaldin these calculations show fluctuations that can be tied to changes in the eruptive character inferred from seismic records and later geologic studies the remote location of this volcano made satellite images a necessary observation tool for this eruption to date this is the longest thermal precursory activity preceding a sub plinian eruption recorded by satellite images in the region this type of thermal monitoring of remote volcanoes is central in the efforts of the alaska volcano observatory to provide timely warnings of volcanic eruption and mitigate their associated hazards to air traffic and local residents

40ar 39ar and k ar dating on the volcanic rocks in the songliao basin ne china constraints on stratigraphy and basin dynamics precise 40ar 39ar and k ar ages were determined on sanidine and whole rock separates of volcanic rocks in the songliao basin sb the volcanism is characterized by a series of continual and episodic eruptions in the late jurassic 147 157 ma and early cretaceous 113 136 ma a fairly accurate chronostratigraphic column was first established based on those data the volcanic activities happened synchronously with closure of the mongolia okhotsk ocean north to the sb structures of the volcanogenic successions are s dipping or se dipping fault blocks coupled with n dipping or nw dipping major detachment systems distribution of the volcanics revealed by high resolution seismic reflections is neither restricted within nor in agreement with the framework of the overlying sedimentary sequence striking nne this new evidence fits the overlap model proposed in the present paper that formation of the volcanic successions in the sb is related to the subduction of the mongolia okhotsk plate under the mongolia north china block during the jurassic and early cretaceous whereas the overlying sedimentary sequence unconformably on the volcanics is tectonically controlled by the oblique subduction of the pacific plate under the eurasian plate since late aptian in addition the coal bearing epiclastic sediments intercalating the volcanics were deposited at the subduction quiescence episodes when extensional collapse occurred

scale dependent location of hydrothermal vents stress field models and infrared field observations on the fossa cone vulcano island italy article i nfo hydrothermal venting occurs on numerous volcanoes of various age setting topographic and structural expression vent locations are commonly found not within volcanic craters only but predominantly at the crater margins and topographic highs a case example is vulcano island italy where the control on such vent locations along crater margins remained poorly understood however this paper describes numerical models combined with field observations and infrared imaging to explore the mechanisms that control the ascent paths of fluids in the fossa cone on vulcano using finite element modelling we calculate the gravitational stress in the volcanic edifice imposed by the topography results predict hydrofractures to be arranged in radial patterns at depth and in concentric patterns close to the surface furthermore low compressive stress values are found at the rims of the nested craters we compare the stress models to fumarole field data using a forward looking infrared camera we recorded images of the entire cone images were assembled to a mosaic and geocoded providing the first map of a remotely sensed temperature field in high resolution at la fossa the degassing and high temperature anomalies are found to be located mainly at the crests of the craters predominately in the northern and southern sector of the main crater therefore the stress distribution favours and indeed corresponds to the occurrence of fumaroles at la fossa the stress models also yield compression at the bottom of the crater where temperatures are cool thus we consider that the overall distribution of the fumaroles at the fossa cone is controlled by topography additional mechanisms contribute to the exact position of the degassing sites the influence of the lithological control seems to be strong in the southwestern part of the crater where the fumaroles are located 10 20 m below the inner crater rim in bedded strata in the northern part of the crater the exhalation sites can mainly be found at surface fractures and cracks emphasizing the structural control on the location of the fumaroles at this sector of the fossa cone using combined theoretical modelling and field observations this study helps to shed light into the processes directing fluids in volcanic edifices elsewhere and might contribute to the evaluation of upcoming hazard scenarios

heat flux measurement from thermal infrared imagery in low flux fumarolic zones example of the ty fault la soufriere de guadeloupe monitoring the geothermal flux of a dormant volcano is necessary both for hazard assessment and for studying hydrothermal systems heat from a magma body located at depth is transported by steam to the surface where it is expelled in fumaroles if the heat flow exceeds 500 w m2 if the heat flow is lower than 500 w m2 steam mainly condensates in the soil close to surface and produces a thermal anomaly detectable at the surface in this study we propose a method to quantify low heat fluxes from temperature anomalies measured at the surface by a thermal infrared camera once corrected from the atmospheric and surface effects thermal infrared images are used to compute 1 the excess of radiative flux 2 the excess of sensible flux and 3 the steam flux from the soil to the atmosphere these calculations require measurements of atmospheric parameters temperature wind velocity and humidity and estimations of surface parameters roughness and emissivity this method has been tested on a low flux fumarolic zone of the soufriere volcano guadeloupe island lesser antilles and compared to a flux estimation realized from the thermal gradient measurements into the soil the two methods show a good agreement and a similar precision 267 46 w m2 for the thermal infrared method and 275 50 w m2 for the vertical temperature gradient method if surface roughness is well calibrated

geochronology geochemistry and deformation history of late jurassic early cretaceous intrusive rocks in the erguna massif ne china constraints on the late mesozoic tectonic evolution of the mongol okhotsk orogenic belt abstract this paper presents new zircon and sphene u pb ages biotite and hornblende 40 ar 39 ar ages hf isotopic data and geochemical data for five mesozoic plutons in the erguna massif of ne china these data are used to constrain the late mesozoic tectonic evolution of the mongol okhotsk orogenic belt this new dating when combined with previously published ages indicates that the late jurassic early cretaceous j 3 k 1 intrusive rocks can be subdivided into three stages that represent periods of magmatism during the late jurassic 155 ma early early cretaceous 137 ma and late early cretaceous 123 ma in addition the rocks have undergone later deformation recorded by peak ages of 137 and 123 ma the late jurassic and early early cretaceous intrusive rocks in the study area are dominantly syenogranites and are either a type granites or are classified as alkaline series suggesting that they formed in an extensional environment the late early cretaceous intrusive rocks in this area are generally monzogranitic and were emplaced as dikes in an extensional environment along with coeval bimodal volcanics these data combined with the presence of regional unconformities in the northern part of hebei province and western part of liaoning province and the spatial distribution of coeval volcanic rocks in ne china suggest the late jurassic and early early cretaceous magmatisms and the early early cretaceous deformation in this area occurred in an extensional environment related to the delamination of a thickened part of the crust after closure of the mongol okhotsk ocean in comparison the late early cretaceous deformation and magmatism occurred in an extensional environment related to either delamination of the previously thickened crust related to the mongol okhotsk tectonic regime or the subduction of the paleo pacific plate or the combined influence of these two tectonic regimes

permian geodynamic setting of northeast china and adjacent regions closure of the paleo asian ocean and subduction of the paleo pacific plate abstract northeast china and adjacent regions are located in the central east asian continent and consist tectonically of both the paleo asian and paleo pacific orogens between the siberian platform and sino korean north china block this paper discusses some hotly debated issues concerning the permian geodynamic setting of these regions based on a comprehensive analysis of available geological geochemical paleobiogeographical and paleomagnetic data spatial and temporal distribution of ophiolites and associated continental marginal sequences permian sedimentary sequences spatial distribution and geochemistry of permian magmatic rocks and the evolution of paleobiogeographical realms imply 1 that the permian marine basins in northeast china and adjacent regions include remnants of the paleo asian ocean in southeastern inner mongolia and central jilin province and active continental margins of the paleo pacific ocean 2 that the suture between the siberian and sino korean paleoplates was finally emplaced in the permian and is located in areas from suolunshan solonker eastwards through regions north to the xar moron river in southeastern inner mongolia and then central jilin province to the yanji area and 3 that the permian crustal evolution of northeast china and adjacent regions as well as parts of the siberian paleoplate was influenced by subduction of the paleo pacific oceanic plate finally the permian tectonic framework and paleogeography of northeast china and adjacent regions in central east asia are discussed briefly and early and late permian palinspastic reconstruction maps are provided

volcanic eruptions prediction hazard assessment remote sensing and societal implications in volcanology the period 1991 1994 was very busy with many active volcanoes keeping pace with the higher than average frequency of eruptions about 60 70 per year recorded during the late 1970 s to the late 1980 s simkin 1993 some large and violent eruptions occurred in well populated areas but these passed without the higher death tolls caused by eruptions in the previous decade a reflection perhaps of increased volcanic hazard awareness improved prediction and monitoring and better communication between volcanologists and public officials peterson and tilling 1993 the loss of human life was limited to a little over 1000 with perhaps 750 of these attributable to the mount pinatubo eruption on luzon in the philippines many were killed by post eruption phenomena such as mudflows and by disease in the displaced populations this large eruption which had a world wide atmospheric impact dominates the picture of volcanism in the early 1990 s however significant eruptions also occurred at hudson unzen spurr redoubt hekla mayon galeras rabaul kliuchevskoi etna the most voluminous lava outpourings this century and many other volcanoes here we assess the current state of volcano monitoring and hazard awareness against a backdrop of the eruptions of the past four years and take a look at future developments stressing new techniques in the field of remote sensing

invisible gold in ore and mineral concentrates from the hillgrove gold antimony deposits nsw australia vein hosted mesothermal stibnite gold mineralisation at the hillgrove au sb mine in northeastern new south wales has a halo of veinlet and disseminated auriferous arsenopyrite and arsenian pyrite in metasedimentary and granitic host rocks about 50 55 of the gold produced at hillgrove occurs invisibly in arsenopyrite and pyrite gold losses of 20 into tailings are due to this mineral chemical factor from pixe probe analyses it has been found that arsenopyrite contains 255 1500 ppm au and pyrite 24 223 ppm au with au contents of each mineral correlating moderately with as content arsenopyrite and pyrite also contain anomalous values of cu ag and sb whereas paragenetically later stibnite contains little invisible gold but minor fe as ag cu and pb the precipitation of invisible gold in arsenopyrite and pyrite by a possible fe au 3 as s 3 substitution mechanism may have been facilitated by rapid non equilibrium conditions involving pressure decreases and wall rock reaction sulphidation carbonatisation as a prelude to the main stage of stibnite and gold deposition

geological characteristics and genesis of gold deposits in upper heilongjiang basin upper heilongjiang basin is an important gold metallogenic province found recently gold deposits such as shabaosi laogou shabaosilinchang and ergenhe are strictly controlled by nearly ew trending luoguhe ergenhe brittle ductile shear zone and the ore bodies normally occur in sn ne and nw trending subsidiary tensio shear fractures which were derived from the ductile shear zone in order to probe into the genetic types of shabaosi laogou and other gold deposits as well as the ore prospecting potential in this area the authors carried out a detailed field investigation and studied geological characteristics of typical deposits meanwhile based on the homogenization temperature whole components laser raman microprobe analyses of fluid inclusions in quartz and h o s and pb isotopes the authors systematically discussed the metallogenesis of the gold deposits the results show that these gold deposits are characterized by poor sulfides with 3 sulfide minerals mainly pyrite fluid inclusions in the gold deposits can be divided into aqueous two phase type co 2 bearing three phase type and pure co 2 type the sulfur lead hydrogen and oxygen isotopic components of typical ores and ore forming fluids indicate that 34s values of sulfides pyrite pyrrhotite and stibnite range from 1 6 to 9 6 18o values of ore forming fluids from 1 3 to 6 6 while d from 89 to 135 lead isotopes of ores have characteristics of the orogenic belt the cations of the ore forming fluids are mainly na and k while the anions are chiefly cl and so 2 4 the vapor phase components of the ore forming fluids are composed mainly of h 2o co 2 and n 2 with minor amounts of h 2 o 2 co ch 4 c 2h 4 c 2h 6 c 3h 8 c 6h 6 and h 2 whereas the content of ch 4 evidently increased at the late ore forming stage the ore forming fluids belong to h 2o nacl co 2 ch 4 system characterized by low salinity averagely 5 0 the homogenization temperature of fluid inclusions ranges from 266 5 to 295 2 belonging to the mesothermal type the ore type is of au sb association studies show that the gold deposits are similar to the orogenic gold deposits in geological and geochemical characteristics and can hence be assigned to the epizonal orogenic subtype the formation of the ore deposits was closely related to mongolia okhotsk orogeny

a total volatile inventory for masaya volcano nicaragua nerc project magma dynamics at persistently degassing basaltic volcanoes a novel approach to linking volcanic gases and magmatic volatiles within a physical model ne f004222 1 and ne f005342 1

late kinematic timing of orogenic gold deposits and significance for computer based exploration techniques with emphasis on the yilgarn block western australia abstract orogenic gold deposits are a widespread coherent group of epigenetic ore deposits that are sited in accretionary or collisional orogens they formed over a large crustal depth range from deep seated low salinity h2o co2 ch4 n2 ore fluids and with au transported as thio complexes regional structures provide the main control on deposit distribution in many terranes first order faults or shear zones appear to have controlled regional fluid flow with greatest ore fluid fluxes in and adjacent to lower order faults shear zones and or large folds highly competent and or chemically reactive rocks are the most common hosts to the larger deposits focusing of supralithostatic ore fluids into dilatant zones appears to occur late during the evolutionary history of the host terranes normally within d3 or d4 in a d1 d4 deformation sequence reactivation of suitably oriented pre existing structures during a change in far field stress orientation is a factor common to many deposits and repeated reactivation may account for multiple mineralization episodes in some larger deposits absolute robust ages of mineralization support their late kinematic timing and in general suggest that deposits formed diachronously towards the end of the 100 to 200 m y long evolutionary history of hosting orogens for example in the yilgarn block a region specifically emphasised in this study orogenic gold deposits formed in the time interval between 40 and 90 m y with most about 60 to 70 m y after the youngest widespread basic ultrabasic volcanism and towards the end of felsic magmatism the late timing of orogenic gold deposits is pivotal to geologically based exploration methodologies this is because the present structural geometries of i the deposits ii the hosting goldfields and iii the enclosing terranes are all essentially similar to those during gold mineralization at least in their relative position to each other thus interpretation of geological maps and cross sections and three dimensional models can be used to accurately simulate the physical conditions that existed at the time of ore deposition it is particularly significant that the deposits are commonly related to repetitive and predictable geometries such as structural heterogeneities within or adjacent to first order structures around rigid granitoid bodies or in specific locked up fold thrust structures importantly the two giant greenstone hosted goldfields kalgoorlie and timmins show a remarkably similar geometry at the regional scale computer based stress mapping and gis based prospectivity mapping are two computer based quantitative methodologies that can utilize and take advantage of the late timing aspect of this deposit type to provide important geological aids in exploration both in broad regions and more localized goldfields both require an accurate and consistent solid geology map stress mapping requires knowledge of the far field stresses during mineralization and the empirical prospectivity mapping requires data from a significant number of known deposits in the terrane the kalgoorlie terrane in the yilgarn block meets these criteria and illustrates the potential of these methodologies in the exploration for orogenic gold deposits low minimum stress anomalies interpreted to represent dilational zones during gold related deformation coincide well with the positions of known goldfields rather than individual gold deposits in the terrane and there are additional as yet unexplained anomalies the prospectivity analysis confirms that predictable and repetitive factors controlling the siting of deposits are i proximity to and orientation and curvature of granitoid greenstone contacts ii proximity to segments of crustal faults which strike in a preferred direction iii proximity to specific lithological contacts which have similar preferred strike iv proximity to anticlinal structures and v the presence of preferred reactive host rocks e g dolerite the prospectivity map defines a series of anomalous areas which broadly conform to those of the stress map 78 correspondence the most prospective category on this map covers less than 0 3 of the greenstone belts and yet hosts 16 of the known deposits which have produced 80 of known gold thus it discriminates in favour of the larger economically more attractive deposits in the terrane the successful application of stress mapping and prospectivity mapping to geology based exploration for orogenic gold deposits indicates that more quantitative analysis of geological map data is a profitable line of research the computer based nature of these methodologies is ideal for the production of an ultimate integrated deposit target map which can be compared to other more conventional targeting parameters such as geophysical and geochemical anomalies such an integrated strategy appears the way forward in the increasingly difficult task of cost effective global exploration for orogenic gold deposits in poorly exposed terranes

geodynamic setting of mesozoic magmatism in ne china and surrounding regions perspectives from spatio temporal distribution patterns of ore deposits abstract north eastern china and surrounding regions host some of the best examples of phanerozoic juvenile crust on the globe however the mesozoic tectonic setting and geodynamic processes in this region remain debated here we attempt a systematic analysis of the spatio temporal distribution patterns of ore deposits in ne china and surrounding regions to constrain the geodynamic milieu from an evaluation of the available geochronological data we identify five distinct stages of ore formation 240 205 ma 190 165 ma 155 145 ma 140 120 ma and 115 100 ma the triassic 240 205 ma magmatism and associated mineralisation occurred during in a post collisional tectonic setting involving the closure of the paleo asian ocean the early mid jurassic 190 165 ma events are related to the subduction of the paleo pacific ocean in the eastern asian continental margin whereas in the erguna block these are associated with the subduction of the mongol okhotsk ocean from 155 to 120 ma large scale continental extension occurred in ne china and surrounding regions however the late jurassic magmatism and mineralisation events in these areas evolved in a post orogenic extensional environment of the mongol okhotsk ocean subduction system the early stage of the early cretaceous events occurred under the combined effects of the closure of the mongol okhotsk ocean and the subduction of the paleo pacific ocean the widespread extension ceased during the late phase of early cretaceous 115 100 ma following the rapid tectonic changes resulting from the paleo pacific oceanic plate reconfiguration

analysis of active volcanoes from the earth observing system abstract a study of volcanic activity and its effects on the atmosphere is one of 28 interdisciplinary investigations for the earth observing system eos due to be launched in 1997 and 1999 the volcanology investigation will include long and short term monitoring of selected volcanoes the detection of precursory activity associated with unanticipated eruptions and the detailed study of on going eruptions the data collected will allow us to address two aspects of volcanism volcanic padforms and the atmospheric effects of eruptions a variety of instruments on the two nasa eos platforms together with supplemental data from the japanese and european platforms will enable the study of local to regional scale thermal and deformational features of volcanoes and the chemical and structural features of volcanic eruption plumes and aerosols this investigation fits well within the overall goal of the eos project which is to study the regional and global interrelationships between components of the earth system because it specifically investigates the links between volcanism atmospheric chemistry and short term 1 3 year climate change