rare earth element signatures of economic and sub economic porphyry copper systems in urumieh dokhtar magmatic arc udma iran abstract a wide variety of porphyry copper deposits have been reported along the cenozoic urumieh dokhtar magmatic arc in iran the formation of these deposits is attributed to closure of neo tethys and the subsequent collisional tectonic regime during the tertiary this study presents whole rock rare earth element ree data for the giant to small sarcheshmeh meiduk sungun darreh zerreshk dalli iju parkam and ali abad with sub economic daraloo and reagan porphyry copper systems the data indicate a temporal and geochemical evolution from sub economic porphyry systems to economic deposits all the economic and sub economic porphyry copper systems exhibit lree enrichment relative to hree whereas the economic deposits exhibit a relatively steep downward lree to hree profile reflecting higher lree abundance the eu anomalies vary from distinct negative in sub economic deposits eu eu 0 28 0 70 to either markedly less negative or positive anomalies eu eu 0 45 1 67 in economic deposit the economic porphyry deposits are characterized by relatively high la sm and sm yb values representing high crustal assimilation in a relatively thickened crust and provide insight into fractionation of hornblende with minor garnet in deep crustal parts mash zone compared with sub economic deposits the steep downward lree to mree and flatter to slightly upward mree to hree in economic deposits indicate hornblende involvement magma evolution toward more volatile content it seems that in an ongoing process of closure of neo tethys during compression and crustal shortening the early eocene oligocene sub economic intrusions are followed by adakite like hydrous miocene and younger economic cu bearing intrusions

purple haze combined geochemical and pb sr isotope constraints on colourants in celtic glass abstract the composition of 2977 late prehistoric glass objects was investigated to derive information on the nature of the colourants used 2673 late iron age celtic la tene bracelet fragments from the netherlands and austria and 51 early iron age beads from the netherlands were analysed hand held xrf analyses demonstrated that all glass objects were of the soda silica lime type which has a presumed origin in the eastern mediterranean copper was used as colourant in the form of copper filings in most of the early iron age glass beads to give recycled glass a blue green colour the vast majority 98 of the translucent iron age glass was coloured using cobalt blue manganese purple colourless antimony colourless and iron green manganese however was added to all glass contributing additional amounts of elements like copper cobalt and iron opaque decorations were produced using antimony or a combination of tin and lead ree analyses on a selection of representative objects indicate that the manganese ores in translucent glass are of hydrogenetic diagenetic early iron age or hydrothermally influenced diagenetic late iron age types strontium isotope ratios show mixing between a calcite related seawater source 0 709 and manganese ores with isotope ratios of 0 70766 lead isotope ratios are dominated by colourant derived pb the isotope ratios of the manganese used to produce translucent glass and lead used for opaque glass decorations fall in the same range the most likely general provenance of both lies on lavrion or the western cycladic islands although an origin in the central taurus or the sinai mountains cannot be excluded the conclusion is that manganese ore used for colourants contributes significantly to the ree concentration in the glass including nd as well as to sr and pb this needs to be taken into account when using concentrations or isotope ratios of these elements for provenancing other raw materials like sand and calcium carbonate this appears to be the case for all antique soda lime silica glass

a new hypothesis on parameters controlling the formation and size of porphyry copper deposits implications on thermal gradient of subducted oceanic slab depth of dehydration and partial melting along the kerman copper belt in iran abstract porphyry copper deposits in the tethyan metallogenic belt broadly occur in early mesozoic late mesozoic paleogene and neogene within a wide range of tectonic setting these deposits in iran often occur within the cenozoic urumieh dokhtar magmatic arc udma mostly in the kerman porphyry copper belt kpcb located in the southeast of this arc these deposits along the udma are mainly associated with the granitoids of miocene age 18 82 9 20 ma in this research geochemical characteristics pb and sr isotopes tectonic environment oxidizing conditions and source of magmas for the most important porphyry copper deposits of the udma have been compared and discussed on the basis of trace element discrimination diagrams the kerman belt granitoids formed in a volcanic arc type setting whereas the jebal barez granitoids seem to have formed in a different tectonic setting the eu eu of granitoids from the kerman belt are greater than 1 2 representing the oxidizing conditions for the crystallization of the granitoid magma whereas jebal barez granitoids were formed under reducing conditions the sr y ratio for kerman granitoids is greater than 60 indicating adakitic affinities and la yb n for these granitoid rocks is between 17 and 35 suggesting that their parental magma was generated from a deep garnet bearing source based on 87sr 86sr i values for kerman belt granitoids of 0 704 0 705 it is suggested that parental magmas originated from a subducted oceanic slab in the sarcheshmeh porphyry copper deposit the thermal gradient of the oceanic slab at depth was less than 9 c km warm cold slab the oceanic slab was highly hydrated and more than 80 of the water within the oceanic slab was released in the deep zone of the sub arc region at a depth of 110 130 km under saturated conditions the oceanic slab partially melted 20 25 a large volume of magma and magmatic water formed sarcheshmeh as a giant porphyry copper deposit in the iju deposit a small porphyry copper deposit the oceanic slab was slightly hydrated and minor water was released at the depth of 110 130 km a small volume of magma was formed due to water undersaturated melting conditions finally a new hypothesis is introduced regarding the roles of down dip thermal gradient of the oceanic slab water content depth of dehydration and degree of partial melting of oceanic slab which are important controls on the formation and size of the porphyry copper deposits within continental volcanic arcs

the sarcheshmeh porphyry copper deposit kerman iran a mineralogical analysis of the igneous rocks and alteration zones including halogen element systematics related to cu mineralization processes abstract the giant sarcheshmeh porphyry copper deposit is located 65 km southwest of kerman city southeastern iran numerous miocene porphyry stocks and dykes intruded thick sequences of upper cretaceous sedimentary and eocene volcanic rocks hypogene and supergene porphyry cu mineralization occurs within the granodioritic porphyry and host rock sequence which was extensively altered to a dominantly potassic phyllic and argillic assemblage with interstitial to distal propylitic types biotite bearing assemblages occur as both primary phenocrysts and secondary replacements showing variable size colour and shape fluorine contents 0 22 to 1 33 wt and x mg 0 54 to 0 71 in biotites from the potassic and phyllic zones are higher than those of non mineralized granitoids f 0 09 to 0 56 wt x mg 0 43 to 0 54 whereas their cl contents cl 0 05 to 0 24 wt are lower than those of the non mineralized granitoids cl 0 11 to 0 45 the biotites from the phyllic zone have higher log f h 2 o f hf and log f h 2 o f hcl values than those of the potassic zone as well as the granitoid and andesitic dykes the log f hf f hcl values determined for the granitoid potassic and phyllic zones are similar though more negative than those of the andesitic dykes the log f hf f hcl values have a similar range for biotite from the granitoid and potassic and phyllic zones the halogen fugacity ratios established for fluids associated with the sarcheshmeh deposit from their f and cl contents in biotite show that the granitoid potassic zone and phyllic zone are increasingly affected by meteoric waters the fluids that circulated in the phyllic zone are predominantly of meteoric origin possibly overprinting original phyllic zone halogen contents the cl intercept values of biotite in the granitoid and phyllic and potassic are similar to other ore forming systems and tend to be more cl rich than cl intercept values of biotites in common igneous rocks calculated f cl intercept values for biotite in the granitoid and potassic zone are also consistent with many other porphyry copper forming systems

petrogenesis of post collisional a type granitoids from the urumieh dokhtar magmatic assemblage southwestern kerman iran constraints on the arabian eurasian continental collision abstract three plutons deh siahan bande bagh and baghe khoshk sharghi collectively referred to as the dbb hereafter in southwestern kerman in the southeastern part of the urumieh dokhtar magmatic assemblage udma of the zagros orogenic belt differ from the typical calc alkaline metaluminous i type intrusions of the region the dbb intrusions have a distinct lithological assemblage varying from diorite through monzogranite and monzonite to alkali feldspar syenite and alkali granite the dbb granitoids are metaluminous to slightly peraluminous alkaline to shoshonitic in composition and have high total alkali contents with k2o na2o high feot mgo values and low cao and mgo contents they are enriched in some liles such as rb and th and hfses such as zr y and rees except eu and depleted in sr and ba relative to primordial mantle and have low concentrations of transitional metals these features along with various geochemical discriminant diagrams suggest that the dbb granitoids are post collisional a type granitoids which had not been recognized previously in the udma the chondrite normalized ree patterns of the dbb granitoids show slightly enriched light rees la sm n 2 26 4 13 negative eu anomalies eu eu n 0 19 0 74 and flat heavy ree patterns gd yb n 0 80 1 87 the negative eu anomaly indicates an important role for plagioclase and or k feldspar during fractional crystallization whole rock rb sr isotope analysis yields an isochron age of 33 1 ma with an initial 87sr 86sr value of 0 7049 0 0001 whole rock sm nd isotope analysis gives endt values from 2 56 to 3 62 at 33 ma the positive endt and low isr values of the dbb granitoids together with their tdm of 0 6 0 7 ga suggest their formation from partial melting of a lithospheric mantle source modified by fluids or melts from earlier subduction processes melting of lithospheric mantle occurred via a dehydration melting process at pressures below the garnet stability field as a consequence of lithospheric mantle delamination or break off of a subducted slab and melting of the lithospheric mantle by upwelling of hot asthenosphere on the basis of rb sr age dating and the post collisional geochemical signatures of the dbb granitoids along with extensive pre collisional volcanic eruptions in middle eocene we suggest late eocene for the time of collision between the arabian and central iranian plates this also implies that the calc alkaline i type intrusions in the southwestern kerman and in other parts of the udma may have formed in a post collisional context

rise and fall of late pleistocene pluvial lakes in response to reduced evaporation and precipitation evidence from lake surprise california widespread late pleistocene lake systems of the basin and range province indicate substantially greater moisture availability during glacial periods relative to modern times but the climatic factors that drive changes in lake levels are poorly constrained to better constrain these climatic forcing factors we present a new lacustrine paleoclimate record and precipitation estimates for lake surprise a closed basin lake in northeastern california we combine a detailed analysis of lake hydrography and constitutive relationships describing the water balance to determine the influence of precipitation evaporation temperature and seasonal insolation on past lake levels at its maximum extent during the last deglaciation lake surprise covered 1366 km 2 36 of the terminally draining surprise valley watershed using paired radiocarbon and 230 th u analyses we dated shoreline tufa deposits from wave cut lake terraces in surprise valley california to determine the hydrography of the most recent lake cycle this new lake hydrograph places the highest lake level 176 m above the present day playa at 15 19 0 18 calibrated ka 14 c age this significantly postdates the last glacial maximum lgm when lake surprise stood at only moderate levels 65 99 m above modern playa similar to nearby lake lahontan to evaluate the climatic factors associated with lake level changes we use an oxygen isotope mass balance model combined with an analysis of predictions from the paleoclimate model intercomparison project 3 pmip3 climate model ensemble our isotope mass balance model predicts minimal precipitation increases of only 2 18 during the lgm relative to modern compared to an 75 increase in precipitation during the 15 19 ka highstand lgm pmip3 climate model simulations corroborate these findings simulating an average precipitation increase of only 6 5 relative to modern accompanied by a 28 decrease in total evaporation driven by a 7 c decrease in mean annual temperature lgm pmip3 climate model simulations also suggest a seasonal decoupling of runoff and precipitation with peak runoff shifting to the late spring early summer from the late winter early spring our coupled analyses suggest that moderate lake levels during the lgm were a result of reduced evaporation driven by reduced summer insolation and temperatures not by increased precipitation reduced evaporation primed basin and range lake systems particularly smaller isolated basins such as surprise valley to respond rapidly to increased precipitation during late heinrich stadial 1 hs1 post lgm highstands were potentially driven by increased rainfall during hs1 brought by latitudinally extensive and strengthened midlatitude westerly storm tracks the effects of which are recorded in the region9s lacustrine and glacial records these results suggest that seasonal insolation and reduced temperatures have been underinvestigated as long term drivers of moisture availability in the western united states

initial transient response of the winter polar stratospheric vortex to idealized equatorial pacific sea surface temperature anomalies in the ncar waccm abstractperpetual winter simulations using the ncar whole atmosphere community climate model waccm are conducted to document the differences of the initial transient response of the boreal winter northern hemisphere stratospheric polar vortex to central cpw and eastern pacific warming epw events idealized patches of positive sea surface temperature sst anomalies are superimposed onto a climatological sst field to mimic canonical cpw and epw forcings a 20 member ensemble was created by varying initial atmospheric conditions for both cpw and epw cases in the ensemble average the vortex weakens under both cpw and epw forcing indicated by a negative zonal mean zonal wind tendency this tendency is mainly tied to changes in the eddy driven mean meridional circulation mmc a negative anomaly in the eddy momentum flux convergence also plays a secondary role in the weakening the vortex response however differs dramatically among individual ensemble members a few ensemble members exhibit initial

lead isotopic signatures of porphyry copper deposits in oceanic and continental settings colombian andes abstract three discrete sub belts of porphyry copper type mineralization are recognized in the colombian andes a western eocene sub belt an eastern jurassic to early cretaceous sub belt and between them a central miocene sub belt the western sub belt is part of an oceanic domain constituted by oceanic crust and overlying immature island arc rocks the eastern sub belt is within a continental domain underlain by the leading edge of the guayana shield and the central sub belt spans the faulted boundary between them the thicker continental crust includes important granulitic rocks which crop out locally as in the vicinity of the mocoa porphyry copper deposit pb isotopic ratios were determined for pyrite samples collected from 6 porphyry copper centers 3 in the western sub belt 2 in the eastern sub belt and one in the central sub belt ratios fall into 3 discrete populations the most radiogenic values represent the western sub belt the least radiogenic represent the eastern sub belt and an intermediate value corresponds to the central sub belt ratios therefore become progressively less radiogenic from the western oceanic domain to the eastern cratonic domain comparison of the pb isotopic ratios with those given in the literature for possible source materials for colombian porphyry copper leads enables the subcontinental mantle wedge subducted oceanic crust and subducted metalliferous sediments to be discounted as principal sources the relatively radiogenic signatures of 5 of the porphyry copper centers appear to be broadly compatible with either a subducted pelagic sediment source or an upper continental crust source whereas the sixth center mocoa is characterized by a distinctly less radiogenic 206 pb 204 pb ratio an admixture of a relatively small percentage of non radiogenic pb from granulitic material in the upper crust with the more radiogenic pb typical of the western sub belt centers could account for the mocoa data because much of the upper crustal section in the region of mocoa is thought to be dominated by granulitic material the radiogenic pb component could be best derived from subducted pelagic sediments if this is the case then a subducted pelagic sediment source could dominate the pb isotopic signatures of all colombian porphyry copper mineralization with some of the pb isotopic differences being produced by selective contamination with upper crustal leads of variable character if this conclusion is correct then the fundamental metal budgets of colombian porphyry copper systems are probably largely independent of upper crustal influences

supergene copper mineralization at the lakeshore mine pinal county arizona there are six copper bearing supergene mineral assemblages at the lakeshore porphyry copper deposit these assemblages form zones which have been mapped throughout the deposit the zones are named for their principal copper bearing minerals the chalcocite zone the cuprite native copper zone the brochantite zone the chrysocolla zone the copper wad zone and the goethite zone two distinct episodes of oxidation have affected the lakeshore deposit the first resulted in the creation of a chalcocite enrichment blanket and a large volume of chrysocolla mineralization the chalcocite enrichment blanket was largely destroyed during the second episode and the brochantite zone cu 4 so 4 oh 6 was formed the lakeshore porphyry copper deposit is a sulfur poor system without a phyllic pyrite rich alteration halo there is no leached capping in the classic sense at the lakeshore deposit the goethite zone which contains an average of 0 3 percent copper occupies the relative position of a leached capping protore mineralization and alteration patterns governed the formation of the chrysocolla brochantite and chalcocite zones the chalcocite and brochantite zones formed in rocks which previously contained abundant hypogene pyrite and chalcopyrite mineralization the antecedents of the chrysocolla zone contained much less pyrite and chalcopyrite and more acid consuming silicates such as biotite and plagioclase than the antecedents of the chalcocite and brochantite zones the geochemical changes associated with the formation of the chrysocolla zone are consistent with the destruction of biotite and plagioclase and the precipitation of gypsum and chrysocolla the geochemical changes associated with the formation of the chalcocite and brochantite zones are consistent with the recrystallization of biotite to smectite and vermiculite the neutralization of copper bearing weathering solutions by plagioclase and biotite resulted in widespread dissemination of copper into altered phenocryst sites a complex assemblage of copper bearing clay or chrysocolla or both is present in the altered phenocrysts there is a continuous range of compositions from chrysocolla to copper bearing clay in altered plagioclase phenocrysts there is no continuous solid solution between chrysocolla and copper bearing clay in altered biotite phenocrysts or in supergene veinlets

mine drainage water from coal mines of kerman region iran two types of mine drainage water were recognized in kerman coalfield namely neutral to alkaline and acid amd both types contain a high level of trace metal concentrations with a higher level in amd trace metals from the coal mine waters of kerman coalfield are mainly present as adsorption on fe and mn oxide and hydroxide particles and to a lesser extent as sulfate simple metal ions and as metal sorption on clay particles and hydrous aluminum oxides

porphyry cu mo au deposits related to melting of thickened mafic lower crust examples from the eastern tethyan metallogenic domain abstract most porphyry cu deposits in the world occur in magmatic arc settings and are formed in association with calc alkaline arc magmas related to subduction of oceanic lithosphere this contribution reviews a number of significant porphyry cu deposits in the eastern tethyan metallogenic domain they widely occur in a variety of non arc settings varying from post late collisional transpressional and extensional environments to intracontinental extensional environments related to orogenic and anorogenic processes their spatial temporal localization is controlled by strike slip faults orogen transverse normal faults lineaments and their intersections in these non arc settings these deposits are dominated by porphyry cu mo deposits with minor porphyry cu au and epithermal au deposits and exhibit a broad similarity with those in magmatic arcs the associated magmas are generally hydrous relatively high fo2 high k calc alkaline and shoshonitic and show geochemical affinity with adakites they are distinguished from arc magmas and or oceanic slab derived adakites by their occurrence as isolated complexes high k2o contents 1 2 8 5 and much wider range of end t values 10 to 3 and positive ehf t values 4 6 to 6 9 these potassic magmas are most likely formed by partial melting of thickened juvenile mafic lower crust or delaminated lower crust but also involving various amounts of asthenospheric mantle components key factors that generate hydrous fertile magmas are most likely crust mantle interaction processes at the base of thickened lower crust in non arc settings rather than oceanic slab dehydration as in arc settings breakdown of amphibole in thickened lower crust e g amphibole eclogite and garnet amphibolite during melting is considered to release fluids into the fertile magmas leading to an elevated oxidation state and higher h2o content necessary for development of porphyry cu mo au systems copper and au in hydrous magmas are likely derived from mantle derived components and or melts which either previously underplated and infiltrated at the base of the thickened lower crust or were input into the primitive magmas by melt mantle interaction in contrast mo and part of the s in the fertile magmas are probably supplied by old crust during melting and subsequent ascent

mo isotope fractionation during hydrothermal evolution of porphyry cu systems we present mo isotope compositions of molybdenite types from three successive stages of ore deposition in several porphyry copper deposits of the kerman region iran the data provide new insights into controlling processes on mo isotope fractionation during the hydrothermal evolution of porphyry systems the mo isotope compositions of 27 molybdenite samples show wide variations in 97mo ranging from 0 37 to 0 92 the data reveal that molybdenites in the early and transitional stages of mineralization preferentially 2h polytypes 97mo mean 0 35 have higher 97mo values than late stage mainly 3r polytypes 97mo mean 0 02 molybdenites this trend suggests that fractionation of mo isotopes occurred in high temperature stages of mineralization and that hydrothermal systems generally evolve towards precipitation of molybdenite with lower 97mo values taking into account the genetic models proposed for porphyry cu deposits along with the temperature dependent fractionation of mo isotope ratios it is proposed that large variations of mo isotopes in the early and the transitional stages of ore deposition could be controlled by the separation of the immiscible ore forming fluid phases with different density ph and o2 properties i e brine and vapor the fractionation of mo isotopes during fluid boiling and rayleigh distillation processes likely dominates the mo isotope budget of the remaining ore forming fluids for the late stage of mineralization the lower 97mo values in the late stage of mineralization can be explained by depletion of the late ore forming hydrothermal solutions in 97mo as these fluids have moved to considerable distance from the source finally the relationship observed between mos2 polytypes 2h and 3r and their mo isotopic compositions can be explained by the molecular vibration theory in which heavier isotopes are preferentially partitioned into denser primary 2h mos2 crystals

modulations in the planetary wave field induced by upward propagating rossby wave packets prior to stratospheric sudden warming events a case study a diagnostic framework is introduced in which anomalous zonally averaged rossby wave activity injection into the stratosphere is decomposed into a contribution solely from zonally confined upward propagating rossby wave packets and another from interaction of the wave packets with the climatological planetary waves to pinpoint the tropospheric sources of the wave packets a particular form of wave activity flux is evaluated for the associated circulation anomalies the framework is applied to reanalysis data for the period prior to a stratospheric sudden warming ssw event in january 2006 which was associated with two successive events of above normal wave activity injection from the troposphere in the earlier event a pair of wave packets that emanated from tropospheric anomalies over the north pacific and over europe enhanced the upward wave activity injection which was augmented further by their interaction with the climatological planetary wave in contrast in the later period a wave packet that emanated from an anticyclonic anomaly over the north atlantic is found to be the primary contributor to the enhanced planetary wave activity injection while its interaction with the climatological planetary wave contributed negatively the predominant importance of the sole contribution from a single wave packet is also found in a major ssw event observed over antarctica in september 2002 these results indicate that the diagnostic framework presented in this study is a useful tool for understanding the interaction between anomalies associated with zonally confined wave packets and climatological mean planetary waves in the study of stratosphere troposphere dynamical coupling copyright 2009 royal meteorological society

identification of blind geothermal resources in surprise valley ca using publicly available groundwater well water quality data abstract geothermal resource exploration is generally limited to areas with surface expressions of thermal activity fumaroles and hot springs or relies on expensive geophysical exploration techniques in this study the hidden subsurface distribution of geothermal fluids has been identified using a free and publicly available water quality dataset from agricultural and domestic water wells in surprise valley northeastern california thermally evolved waters in surprise valley have element ratios that vary in response to ca carbonate and mg silicate mineral precipitation and have elevated total dissolved solids tds the arid climate in surprise valley leads to surface water evaporation in a closed basin producing high tds na cl co3 so4 brines in three ephemeral alkali lakes and in shallow groundwater under elevated soil co2 conditions evaporated fluids in surprise valley follow a chemical divide that leads to ca carbonate and mg silicate mineral precipitation plots of dissolved element ratios can be used to distinguish groundwater affected by evaporation from water affected by thermal water rock interaction however it is challenging to select components for plotting that best illustrate different fluid evolution mechanisms here we use a principal component analysis of centered log ratio transformed data coupled with geochemical models of fluid evaporation and thermal mixing pathways to identify components to plot that distinguish between groundwater samples influenced by evaporation from those influenced by thermal processes we find that groundwater samples with a thermal signature come from wells that define a coherent linear geographical distribution that closely matches the location of known and inferred faults modification of the general approach employed here provides promise for identifying blind geothermal resources in other locations by applying low cost geochemical modeling and statistical techniques to areas where large groundwater quality geochemical datasets are available

geographical dependence observed in blocking high influence on the stratospheric variability through enhancement and suppression of upward planetary wave propagation abstractprevious studies have suggested the importance of blocking high bh development for the occurrence of stratospheric sudden warming ssw while there is a recent study that failed to identify their statistical linkage through composite analysis applied to high amplitude anticyclonic anomaly events observed around every grid point over the extratropical northern hemisphere the present study reveals a distinct geographical dependence of bh influence on the upward propagation of planetary waves pws into the stratosphere tropospheric bhs that develop over the euro atlantic sector tend to enhance upward pw propagation leading to the warming in the polar stratosphere and in some cases to major ssw events in contrast the upward pw propagation tends to be suppressed by bhs developing over the western pacific and the far east resulting in the polar stratospheric cooling this dependence is found to arise mainly from the sensitivity of the interference between the climatological pws and upward p

a review of the cu ni sulphide deposits in the chinese tianshan and altay orogens xinjiang autonomous region nw china principal characteristics and ore forming processes abstract several cu ni sulphide deposits and occurrences have recently been discovered along parallel deep faults in the chinese tianshan and altay orogenic belts xinjiang province nw china the kalatongke and several other cu ni mineralized intrusions are located along the irtysh fault which separates the altay orogenic belt from the junggar basin the huangshan huangshandong xiangshan tudun erhongwa tula ergen and hongling deposits occur along the kanggurtag suture which separates the jueluotage orogenic belt from the turpan hami tuha basin the baishiquan tianyu and tianxiang deposits are located along the arqikekuduke fault which separates the jueluotage orogenic belt from the central tianshan precambrian terrane the poyi poshi and luodong deposits are located along the baidiwa fault which separates the central tianshan precambrian terrane from the beishan paleozoic rift re os dating of cu ni sulphide ores reveals that these cu ni ore belts formed in a narrow age range of 298 282 ma this age range is about the same as those of associated intrusions and dykes dated by the shrimp zircon u pb method tectonic and geochronological constraints suggest that the amalgamation of continental blocks mainly occurred during the late carboniferous in the central asian orogenic belt large scale hydrothermal and magmatic metallogenesis in the region occurred during post collisional stages of latest carboniferous to early permian age the cu ni sulphide deposits are part of this metallogenic event the cu ni orthomagmatic sulphide deposits in northern xinjiang are represented by 1 net textured type deposits by segregation of a cu ni metal sulphide melt and 2 magma conduit type some mafic ultramafic suites exhibit lithological zoning caused by strong differentiation stratiform orebodies are hosted by ultramafic rocks at the base of the magma chamber good examples are the kalatongke huangshandong and poshi deposits others such as the xiangshan baishiquan tianyu and tula ergen deposits are hosted by magma conduits consisting of peridotite troctolite and pyroxenite these ultramafic rocks either occur within faults or are surrounded by gabbroic and dioritic intrusions these two types of orthomagmatic cu ni sulphide deposits are also distributed along the same ore belts for instance the differentiated sill related huangshandong deposit co exists with the magma conduit type tula ergen deposit in the jueluotage orogenic belt orthomagmatic cu ni sulphide deposits in northern xinjiang formed during post collisional extension and are possibly related to a late carboniferous early permian mantle plume event the mafic ultramafic suites and associated cu ni deposits are commonly accompanied by dyke swarms and are characterized by elongated outcrops occurring along parallel e w trending regional faults these mafic ultramafic suites and accompanying dyke swarms are generally fractionated implying that they were feeders of presently eroded flood basalts

hydrochemistry mineralogy and chemical fractionation of mine and processing wastes associated with porphyry copper mines a case study from the sarcheshmeh mine se iran abstract the sarcheshmeh is one of the largest oligo miocene porphyry cu deposits in the world comparative hydrochemical mineralogical and chemical fractionation associated with mining efflorescence salts and processing wastes of this mine are discussed hydrochemical results showed that rock waste dumps reject wastes and old impoundments of tailings are the main sources of acid mine drainage waters amd that contain potentially toxic metals such as cd co cu mn ni and zn as well as al episodic fluxes of highly contaminated acidic waters were produced in a tailings dam over a short period of time secondary soluble minerals provide important controls on the quality of amd produced especially in old dry tailings impoundments secondary sulfate minerals such as gypsum magnesiocopiapite hydronium jarosite kornelite and coquimbite were found in rock waste drainages and in old weathered reject wastes highly soluble secondary minerals such as gypsum eriochalcite and bonattite are also observed in an evaporative layer on old tailings impoundments chemical fractionation patterns of potentially toxic elements showed that the geochemical behavior of metals is primarily controlled by the mineralogical composition of waste samples elements such as co cr cu mn ni and zn are readily released into the water soluble fraction from efflorescence salts associated with rock waste drainages as well as from the evaporative layer of old tailings potentially toxic elements such as as mo and pb are principally adsorbed or co precipitated with amorphous and crystalline fe oxides but they may also be associated with oxidizing primary sulfides and residual fractions following the development of the dammed tailings pond the secondary minerals were dissolved producing acidic waters contaminated by al 154 mg l 1 cu 150 mg l 1 cd 0 31 m gl 1 co 2 13 mg l 1 mn 73 7 mg l 1 ni 1 74 mg l 1 zn 20 3 mg l 1 and cl 1690 mg l 1 therefore the potential use of recycled water from the sarcheshmenh dammed tailings pond is diminished by the presence of corrosive ions like cl in highly acidic fluids that promote corrosion of pipes and pumps in the water recycling system

application of aster data for exploration of porphyry copper deposits a case study of daraloo sarmeshk area southern part of the kerman copper belt iran abstract the cenozoic urumieh dokhtar magmatic belt udmb of iran is a major host to porphyry cu mo au deposits pcds most known pcds in the udmb occur in the southern section of the belt also known as the kerman copper belt kcb three major clusters of pcds are distinguished in the kcb and include the miduk sarcheshmeh and daraloo clusters the daraloo and sarmeshk deposits occur in a northwest southeast trending fault zone that is characterized by the presence of a narrow zone of alteration mineralization that contains a series of oligocene granitoids and miocene porphyritic tonalite granodiorite plutons that cut eocene andesitic lava flows and pyroclastic rocks here we use various techniques including different ratio images minimum noise fraction pixel purity index and matched filter processing to process aster data 14 bands and generate maps that portray the distribution of hydrothermal minerals e g sericite kaolinite chlorite epidote and carbonate related to pcd alteration zones in order to validate the aster data follow up ground proofing and related mineralogical work was done which in all cases proved to be positive the results of this work have identified the regional distribution of hypogene alteration zones i e phyllic argillic propylitic and silicic in addition to areas of secondary fe oxide formation which are coincident with known sites of pcds the regional distribution and extent of the alteration zones identified also highlighted the role of regional structures in focusing the mineralizing altering fluids these results demonstrate very convincingly that aster imagery that uses the appropriate techniques is reliable and robust in mapping out the extent of hydrothermal alteration and lithological units and can be used for targeting hydrothermal ore deposits particularly porphyry copper deposits where the alteration footprint is sizeable

petrology and geochemistry of the granitoid complex of boroujerd sanandaj sirjan zone western iran abstract the middle jurassic boroujerd granitoid complex of the sanandaj sirjan zone with a u pb zircon age of 169 172 ma was emplaced in an active continental margin setting this complex consists of three main units an elongate nw se extending granodioritic unit sio2 58 71 wt which is widespread throughout the area a quartz dioritic unit sio2 52 63 wt exposed as small stocks within the granodioritic body and a monzogranitic unit sio2 70 75 wt widely scattered as separate small outcrops through the southern part of the area a series of nw trending aplites and pegmatites are present in the granodioritic unit and its aureole geochemically this complex is metaluminous to slightly peraluminous typical of i type granites it belongs to high k calc alkaline series and displays the geochemical characteristics typical of volcanic arc granites related to an active continental margin e g significant nb ti p and sr depletion isotopic data sri 0 7062 0 7074 and endt 3 02 to 3 62 are consistent with a crustal protolith in addition fractional crystallization may have played an important role in the formation of the whole spectrum of the granitoid types that occur in the boroujerd area

geo genic arsenic contamination in the kerman cenozoic magmatic arc kerman iran implications for the source identification and regional analysis kerman cenozoic magmatic arc kcma is located in the southeastern part of the central iranian volcano plutonic copper belt arsenic contamination from geo genic source is one of the most important environmental concerns in this area the main objective of this study was to determine the role of geothermal related activities in the arsenic contamination for this purpose the old and active geological indicators of the geothermal activities were investigated through the quaternary travertine deposits and the present hydrothermal warm springs respectively results showed that arsenic is highly concentrated ranged mainly from 12 400 to 90 500 mg kg in the reddish brown deposits of the travertine rocks arsenic showed geochemical association with co cu mo sb tl se fe and mn in these samples yukonite ca7fe3 12 aso4 10 oh 2015h2o a rare ca ferric arsenate hydrous mineral was the only as bearing mineral identified in the reddish brown deposits of the travertine rocks arsenic concentration in the hydrothermal warm springs 38 c ranged from 15 900 to 30 500 g l the dominant form was as h3aso30 hydrothermal contaminated waters also were characterized by na cl type and high values of ec 11 400 s cm tds 8300 mg l b 42 700 g l li 3000 g l fe 900 g l sb 82 8 g l and si 47 000 g l and natural anomalies of cs mn mo rb se and tl the obtained hydro geochemical results are similar to those reported in the literature for worldwide hydrothermal waters although natural attenuation processes such as adsorption co precipitation or mixing dilution reduce most of the arsenic contamination from hydrothermal source but some urban and rural communities are still depending on the arsenic contaminated waters with arsenic concentrations higher than recommended values for drinking or irrigation a subject that increases the risk of arsenic related diseases in some areas of the kerman province

contrasting eastern pacific and central pacific types of enso abstract surface observations and subsurface ocean assimilation datasets are examined to contrast two distinct types of el nino southern oscillation enso in the tropical pacific an eastern pacific ep type and a central pacific cp type an analysis method combining empirical orthogonal function eof analysis and linear regression is used to separate these two types correlation and composite analyses based on the principal components of the eof were performed to examine the structure evolution and teleconnection of these two enso types the ep type of enso is found to have its sst anomaly center located in the eastern equatorial pacific attached to the coast of south america this type of enso is associated with basinwide thermocline and surface wind variations and shows a strong teleconnection with the tropical indian ocean in contrast the cp type of enso has most of its surface wind sst and subsurface anomalies confined in the central pacific and tends to onset develop and decay in situ

tropospheric precursors of anomalous northern hemisphere stratospheric polar vortices regional extratropical tropospheric variability in the north pacific and eastern europe is well correlated with variability in the northern hemisphere wintertime stratospheric polar vortex in both the ecmwf reanalysis record and in the whole atmosphere community climate model to explain this correlation the link between stratospheric vertical eliassen palm flux variability and tropospheric variability is analyzed simple reasoning shows that variability in the north pacific and eastern europe can deepen or flatten the wintertime tropospheric stationary waves and in particular its wavenumber 1 and 2 components thus providing a physical explanation for the correlation between these regions and vortex weakening these two pathways begin to weaken the upper stratospheric vortex nearly immediately with a peak influence apparent after a lag of some 20 days the influence then appears to propagate downward in time as expected from wave mean flow interaction theory these patterns are influenced by enso and october eurasian snow cover perturbations in the vortex induced by the two regions add linearly these two patterns and the quasi biennial oscillation qbo are linearly related to 40 of polar vortex variability during winter in the reanalysis record

global atmospheric sensitivity to tropical sst anomalies throughout the indo pacific basin abstract the sensitivity of the global atmospheric response to sea surface temperature sst anomalies throughout the tropical indian and pacific ocean basins is investigated using the ncep mrf9 general circulation model gcm model responses in january are first determined for a uniform array of 42 localized sst anomaly patches over the domain results from the individual forcing experiments are then linearly combined using a statistically based smoothing procedure to produce sensitivity maps for many target quantities of interest including the geopotential height response over the pacific north american pna region and regional precipitation responses over north america south america africa australia and indonesia perhaps the most striking result from this analysis is that many important targets for seasonal forecasting including the pna response are most sensitive to sst anomalies in the nino 4 region 5 n 5 s 150 w 160 e of the central tropical pacific with lesser and sometimes opposite s

the salience of nonlinearities in the boreal winter response to enso north pacific and north america the prominence of nonlinearities in the response to el nino as compared to la nina to moderate el nino events as compared to extreme el ninno events and to different flavors of el nino events are analyzed using the nasa goddard earth observing system chemistry climate model in the central north pacific region where the sea level pressure response to el nino southern oscillation enso peaks nonlinearities are relatively muted in contrast changes to the east of this region i e the far northeastern pacific and to the north of this region over alaska in response to different enso phases are more clearly nonlinear and become statistically robust after more than 15 events are considered the relative prominence of these nonlinearities is related to the zonal wavenumber of the tropical precipitation response associated with these nonlinearities over the far northeastern pacific are nonlinearities in precipitation over western united states and surface temperature over northwest north america and midwestern united states in all regions at least 15 events of each type are necessary before nonlinearities can be identified as statistically significant at the 95 confidence level due to the presence of internal atmospheric variability as there have only been a similar number of enso events to the total needed for significance since 1920 it is not surprising that it has been difficult to establish statistically significant nonlinearities using observational data

application of multivariate statistical methods to indicate the origin and geochemical behavior of potentially hazardous elements in sediment around the sarcheshmeh copper mine se iran multivariate statistical techniques i e correlation coefficient analysis principal components analysis pca and hierarchical cluster analysis ca were applied to the total and water soluble concentrations of potentially hazardous metals in sediments associated with the sarcheshmeh mine one of the largest oligo miocene porphyry copper deposits in the world the samples were analyzed for hazardous metal concentration levels by inductively coupled plasma mass spectrometry method results indicate that the contaminant metals as cd cu mo s sb sn se pb and zn were positively correlated with the total concentrations these hazardous metals also have strong association in the pca and ca results different anthropic versus natural sources of contaminant metals were distinguished by using ca method water soluble fraction of hazardous metals showed that the hydro geochemical behavior of these metals in sediments is different considerably elements such as cd co cr cu fe mn ni s and zn are readily water soluble from contaminated samples especially from evaporative mineral phases while the release of as mo sb and pb into the water is limited by adsorption processes results obtained from the application of multivariate techniques on the water soluble fraction data set show that the hazardous metals are categorized into three groups including 1 ni s co cu cr and fe 2 se mn cd and zn and 3 sb as mo and sn this classification describes the hydro geochemical behavior of hazardous metals in water sediment environments of the sarcheshmeh porphyry copper mine and can be used as a basis in remedial and treatment strategies

propagation of the arctic oscillation from the stratosphere to the troposphere geopotential anomalies ranging from the earth s surface to the middle stratosphere in the northern hemisphere are dominated by a mode of variability known as the arctic oscillation ao the ao is represented herein by the leading mode the first empirical orthogonal function of low frequency variability of wintertime geopotential between 1000 and 10 hpa in the middle stratosphere the signature of the ao is a nearly zonally symmetric pattern representing a strong or weak polar vortex at 1000 hpa the ao is similar to the north atlantic oscillation but with more zonal symmetry especially at high latitudes in zonal mean zonal wind the ao is seen as a north south dipole centered on 40 45 n in zonal mean temperature it is seen as a deep warm or cold polar anomaly from the upper troposphere to 10 hpa the association of the ao pattern in the troposphere with modulation of the strength of the stratospheric polar vortex provides perhaps the best measure of coupling between the stratosphere and the troposphere by examining separately time series of ao signatures at tropospheric and stratospheric levels it is shown that ao anomalies typically appear first in the stratosphere and propagate downward the midwinter correlation between the 90 day low pass filtered 10 hpa anomaly and the 1000 hpa anomaly exceeds 0 65 when the surface anomaly time series is lagged by about three weeks the tropospheric signature of the ao anomaly is characterized by substantial changes to the storm tracks and strength of the midtropospheric flow especially over the north atlantic and europe the implications of large stratospheric anomalies as precursors to changes in tropospheric weather patterns are discussed

structural controls on geothermal circulation in surprise valley california a re evaluation of the lake city fault zone faults and fractures play an important role in the circulation of geothermal fluids in the crust and the nature of that role varies according to structural setting and state of stress as a result detailed geologic and geophysical mapping that relates thermal springs to known structural features is essential to modeling geothermal systems published maps of surprise valley in northeastern california suggest that the lake city fault or lake city fault zone is a significant structural feature cutting obliquely across the basin and connecting thermal springs across the valley newly acquired geophysical data audio magnetotelluric gravity and magnetic combined with existing geochemical and geological data suggest otherwise we examine potential field profiles and resistivity models that cross the mapped lake city fault zone while there are numerous geophysical anomalies that suggest subsurface structures they mostly do not coincide with the mapped traces of the lake city fault zone nor do they show a consistent signature in gravity magnetics or resistivities that would suggest a through going fault that would promote connectivity through lateral fluid flow instead of a single continuous fault we propose the presence of a deformation zone associated with the growth of the range front surprise valley fault the implication for geothermal circulation is that this is a zone of enhanced porosity but lacks length wise connectivity that could conduct fluids across the valley thermal fluid circulation is most likely controlled primarily by interactions between n s trending normal faults

the northwestern margin of the basin and range province part 1 reflection profiling of the moderate angle 30 surprise valley fault abstract seismic reflection profiling demonstrates that the active significant offset surprise valley fault that marks the western boundary of the basin and range province in northernmost california dips at a moderate angle only 30 to 2 km depth a nearby seismic refraction wide angle reflection profile albeit of lower resolution shows the fault plane remains approximately planar to at least 7 km depth variably tilted volcanic strata of known ages within the surprise valley basin demonstrate that 7 km of normal slip occurred along the surprise valley fault within the past 8 4 myr at a time averaged slip rate of 1 2 mm yr and that the fault rotated from an initial dip of as much as 60 to its present dip of 30 the rotation of this isolated fault was not accomplished by domino style rotation as seen elsewhere in the basin and range province but rather by flexural rift shoulder uplift aided by mid crustal flow

island arc affinity of the central iranian volcanic belt abstract three types of tectonic settings are proposed for the central iranian volcanic belt civb namely rift continental margin and post collision settings however geochemical tectonic stratigraphic and metallogenic evidence favor an ensialic island arc setting the discrimination diagrams that have been used in this study are useful for making a distinction between ensialic island arcs and continental margin arcs from which the ensialic island arcs were derived

tectonic evolution of the orogenic belt in the region located between kerman and neyriz abstract tectonic evolution of the orogenic belt in the region located between kerman and neyriz is explored within the context of two ne dipping neotethyan subduction zones the northern subduction zone was responsible for formation of the mesozoic sanandaj sirjan magmatic arc and the late cretaceous shahr babak baft ensimatic back arc extensional basin the southern subduction zone was responsible for formation of the reverse primitive neyriz island arc the central iranian volcanic belt and its line of porphyry copper deposits as well as the rafsanjan back arc extensional basin proto rafsanjan depression due to the collision of the neyriz island arc with the sanandaj sirjan active continental margin the shahr babak baft back arc basin was tectonically inverted into the shahr babak baft ophiolite belt finally the continental collision between the arabian and the central iranian plates took place during the neogene this led to the tectonic inversion of the rafsanjan ensialic basin into the rafsanjan retro arc basin the present rafsanjan depression and emplacement of the syncollision to late or post orogenic granitoid rocks felsic mass in the rafsanjan region

hydrogen isotope study of large scale meteoric water transport in northern california and nevada abstract the depletion of deuterium in surface and shallow groundwaters along a traverse through northern california and nevada is used to model the local hydrologic balance as controlled by the eastward flux of meteoric water in a way not possible by conventional methods when plotted against distance from the pacific ocean our data indicate three hydrologic provinces which differ in their relative degree of openness isotopic variations of groundwater in the first province are governed by rayleigh distillation from the eastward moving storm clouds some 40 of the storm water vapor precipitates out before reaching the california coast and another 16 in the first 55 km across the continent the isotopic depletion in the second hydrologic province is linear with distance and this suggests extensive recycling of terrestrial water the third province constitutes the great basin characterized by the lack of significant hydrogen isotope variation of groundwater is thought to be an isotopically closed system the quantity of water crossing the coast calculated from a model that incorporates the rayleigh distillation equation is approximately equal to the quantity of precipitation along the northern california part of the transect studied this illustrates the importance of evapotranspiration in the terrestrial water budget as well as the dependency of inland areas on the eastward flux of recycled terrestrial water

revisiting the enso ssw relationship abstractstratospheric sudden warming ssw events exhibit pronounced interannual variability based on zonal wind reversals at 60 n and 10 hpa it has been suggested that ssw events occur more preferentially during el nino southern oscillation enso winters both el nino and la nina winters than during enso neutral winters this relationship is reevaluated here by considering seven different ssw definitions for all definitions ssw events are detected more frequently during el nino winters than during enso neutral winters in agreement with a strengthened planetary scale wave activity however such a systematic relationship is not found during la nina winters while three ssw definitions including the wind reversal definition show a higher ssw frequency during la nina winters than during enso neutral winters other definitions show no difference or even lower ssw frequency during la nina winters this result which is qualitatively insensitive to the choice of reanalysis datasets enso indices and

lead isotope data from the sar cheshmeh porphyry copper deposit iran lead isotope compositions of nine sulfide concentrates from ore samples from the sar cheshmeh deposit are reported they range from virtually unaltered granodiorite through varying degrees of potassic alteration to ores showing strong phyllic alteration sericite veins the samples without strong phyllic alteration have fairly uniform lead isotope compositions around 206pb 204pb 18 6 207pb 204pb 15 6 and 208pb 204pb 38 7 two samples with sericite veins have markedly more radiogenic lead it is concluded that the fluid responsible for the potassic alteration and the associated mineralization was essentially magmatic whereas convecting meteoric water from the country rock acted as a mineralizing solution during phyllic alteration in the context of the plumbotectonics model the deposit has a typical orogen signature intermediate between primitive and mature island arc settings

the northwestern margin of the basin and range province part 2 structural setting of a developing basin from seismic and potential field data abstract surprise valley in northeastern california offers an ideal opportunity to examine the structural setting of a developing extensional basin due to its late miocene to recent activity in isolation from other major normal fault bound basins seismic velocity and potential field modeling help determine the nature of basin fill and identify intra basin faults based on a detailed gravity and magnetic profile we identify shallow subsurface basalt flows and several faults within the valley that may accommodate hundreds of meters of vertical offset possibly cutting and offsetting the 30 east dipping surprise valley fault that rotated during footwall tilting of the adjacent warner mountains some of these intra basin faults correspond with mapped quaternary fault scarps but others have no surface expression these faults may represent the currently active fault system within the basin if so they would indicate that basin development is transitioning away from the main range front normal fault to a new set of steep intra basin faults that are more favorable for accommodating regional transtensional strain

decadal changes of enso persistence barrier in sst and ocean heat content indices 1958 2001 decadal changes of el nino southern oscillation enso persistence barriers in various indices of sea surface temperature sst and ocean heat content ohc are examined in this study using observations and ocean data assimilation products for the period 1958 2001 it is found that the sst indices in the eastern and central equatorial pacific exhibit very different decadal barrier variability the variability is large for the eastern pacific sst indices nino1 2 and nino3 whose persistence barriers shifted abruptly in 1976 1977 and 1989 1990 in contrast the central pacific sst indices nino3 4 and nino4 experienced little decadal barrier variability and have had their persistence barriers fixed in spring in the past four decades the zonal mean ohc index averaged over the equatorial pacific shows decadal barrier changes similar to those in the eastern pacific sst indices and always leads the nino3 sst barrier by about one season it is noticed that the sst persistence barrier appeared first in the eastern pacific before 1976 1977 first in the central pacific between 1976 1977 and 1989 1990 and almost simultaneous in both the eastern and central pacific after 1989 1990 these timings coincide with the westward propagating eastward propagating and standing pattern of enso sst anomalies observed in these three periods these results suggest that enso sst anomalies in the equatorial pacific can be considered to consist of two different processes a central pacific process whose phase transition such as onset and barrier always happen in spring and an eastern pacific process whose phase transition and barrier change from decade to decade and are influenced by changes in the mean thermocline depth along the equatorial pacific

a conceptual geochemical model of the geothermal system at surprise valley ca abstract characterizing the geothermal system at surprise valley sv northeastern california is important for determining the sustainability of the energy resource and mitigating hazards associated with hydrothermal eruptions that last occurred in 1951 previous geochemical studies of the area attempted to reconcile different hot spring compositions on the western and eastern sides of the valley using scenarios of dilution equilibration at low temperatures surface evaporation and differences in rock type along flow paths these models were primarily supported using classical geothermometry methods and generally assumed that fluids in the lake city mud volcano area on the western side of the valley best reflect the composition of a deep geothermal fluid in this contribution we address controls on hot spring compositions using a different suite of geochemical tools including optimized multicomponent geochemistry geot models hot spring fluid major and trace element measurements mineralogical observations and stable isotope measurements of hot spring fluids and precipitated carbonates we synthesize the results into a conceptual geochemical model of the surprise valley geothermal system and show that high temperature quartz na k na k ca classical geothermometers fail to predict maximum subsurface temperatures because fluids re equilibrated at progressively lower temperatures during outflow including in the lake city area we propose a model where hot spring fluids originate as a mixture between a deep thermal brine and modern meteoric fluids with a seasonally variable mixing ratio the deep brine has deuterium values at least 3 to 4 lighter than any known groundwater or high elevation snow previously measured in and adjacent to sv suggesting it was recharged during the pleistocene when meteoric fluids had lower deuterium values the deuterium values and compositional characteristics of the deep brine have only been identified in thermal springs and groundwater samples collected in proximity to structures that transmit thermal fluids suggesting the brine may be thermal in nature on the western side of the valley at the lake city mud volcano the deep brine meteoric water mixture subsequently boils in the shallow subsurface precipitates calcite and re equilibrates at about 130 c on the eastern side of the valley meteoric fluid mixes to a greater extent with the deep brine cools conductively without boiling and the composition is modified as dissolved elements are sequestered by secondary minerals that form along the cooling and outflow path at temperatures

an interdecadal change in the influence of the central pacific enso on the subsequent north tropical atlantic spring sst variability around the mid 1980s north tropical atlantic nta spring sea surface temperature sst tends to be warmer cooler than normal in central pacific cp el nino decaying years during 1960s to mid 1980s however the relationship between the nta spring sst and cp el nino southern oscillation enso is weakened after mid 1980s this study presents this interdecadal change and investigates possible causes before the mid 1980s above normal nta sst peaks in post el nino spring the cp el nino can affect nta spring sst by inducing a negative phase of north atlantic oscillation nao anomaly over north atlantic from winter to spring this negative nao circulation weakens the azores high and causes weaker than normal trade wind as a result less heat loses from the nta ocean and above normal sst anomalies generated in contrast after the middle 1980s the connection between cp enso and nao like anomaly has been disrupted this leads to a weakening of cp enso influences on the nta spring sst the observed change in the relationship between nta spring sst and cp enso is likely related to the state of the polar vortex before the middle 1980s the polar vortex is weak this favors the propagation of enso related wave flux the rossby wave trains spread to the stratosphere during el nino conditions and cause weaker than normal polar vortex resulting in a negative nao in the low levels and the subtropical jet is enhanced and elongated which provides a potential waveguide for wave activity propagating to the atlantic through a tropospheric way however the polar vortex is strong after mid 1980s preventing the propagation of the enso related wave trains through the stratosphere or the troposphere

geochronology structure and basin range tectonism of the warner range northeastern california the warner range of northeastern california is a north trending horst at the northwest margin of the great basin the 3 000 m thick bedrock section exposed in the southern part of the range is tertiary in age and it dips homoclinally 20 to 25 west southwest much of the section consists of volcanic rocks whose k ar ages range from about 32 m y near the base of the section to about 14 m y at the top rocks older than about 26 m y are principally andesitic lahars those between 26 and 17 m y are andesitic lava flows and rhyolitic welded ash flow tuffs and those younger than about 17 m y are principally basaltic and andesitic lava flows the homoclinal character of the warner section indicates that block faulting responsible for uplift and tilting of the range began after emplacement of the youngest exposed rocks drilling in the deeply alluviated graben adjacent to the eastern face of the range indicates that aggregate vertical offset across the range front fault is at least 3 600 m the difference in elevation between alluvium in the bottom of the deepest bore hole and the crest of the nearby part of the range thus vertical displacement has occurred at a minimum average rate of 26 cm 1 000 yr during the past 14 m y offset of alluvium along the eastern base of the range records the continuation of block faulting into holocene time the onset of block faulting somewhat less than 14 m y ago and the change in character of volcanic rocks from principally andesitic to principally basaltic in mid miocene time are similar to volcano tectonic events of a much broader region proposed by previous workers the warner range is remarkable for the nearly complete record of regional late cenozoic volcanic and tectonic events found within a single horst

alkaline character of eocene volcanism in the middle part of central iran and its geodynamic situation alkaline volcanic rocks sometimes feldspathoid bearing appear in variable stratigraphic positions within the eocene of the middle part of central iran no magmatic zonation and no k2o enrichment in both time and space can be found in this volcanic sequence these facts together with other geochemical and geological features of the iranian eocene provinces do not agree with a volcanism related to a subduction zone model

some secondary ore formation features of the sar cheshmeh porphyry copper molybdenum deposit kerman iran new secondary mineral features and the control of secondary molybdenum enrichment have now been recognized at the sar cheshmeh copper deposit in part of the deposit copper is locally concentrated within a subvolcanic unit the so called late fine porphyry in amounts that seem too great to have come from the primary phase of the same unit clay minerals are believed to have influenced the deposition of copper by through flowing oxidized zone solutions within this otherwise subeconomic unit these solutions have caused argillic alteration and copper concentration within the plagioclase phenocrysts fractures are filled with chrysocolla but little chrysocolla was observed within the altered plagioclase phenocrysts the scattered layers of sedimentary unroofing breccia horizontal layers of quaternary age accumulated within the depressions at the top of the deposit contain minor amounts of native copper the breccia consists of angular to subangular clasts of local derivation cemented by a matrix of hematite limonite geothite and small rock fragments native copper the only copper mineral associated with the breccia mainly adhers to the cavity walls in the cementing materials the amount of molybdenum within the leached capping of the sar cheshmeh deposit is generally controlled by the amount of pyrite abundant pyrite has caused the retention of molybdenum within the leached capping of the pyritic halo as a result of the more acidic solution during weathering in contrast to the leached zone of the pyrite poor stock where molybdenum is partially mobile

multiphase magma intrusion ore enhancement and hydrothermal carbonatisation in the siah kamar porphyry mo deposit urumieh dokhtar magmatic zone nw iran abstract the siah kamar mo deposit skmd is located at the northwestern termination of the urumieh dokhtar magmatic zone and it is the only porphyry mo ore reserve in iran the exploration program documented 39 2 mt proved reserves 539 ppm mo and 66 4 mt probable reserves 266 ppm mo in this study field and petrographic investigations integrated with geochemical fluid inclusion and quartz chemistry and geochronological u pb zircon re os molybdenite and rb sr multimineral isochron studies are used to propose a metallogenic model for the mo mineralisation in the skmd the geology of the skmd is characterized by the emplacement of a multiphase oligocene basic intermediate at ca 33 30 ma to acidic 29 28 ma magmatic suite which intruded the eocene volcanic country rocks the alteration zone about 4 3 km in size and with a general nw se trend is centered within the main basic porphyry stock grading from an inner potassic sodic zone to peripheral phyllic propylitic halos the late acidic magmatic products stocks and dykes intruded and post dated the main alteration zone two stage mo mineralisation is recognised including i stage 1 disseminated molybdenite coeval with the formation of potassic sodic alteration and minor microscale fsp bt qz po veinlets and ii stage 2 high grade molybdenite carbonate sericite structurally controlled stockwork veining fluid inclusion systematics combined with titaniq thermometry documents a mineralising fluid system compatible with a transition from high temperature up to ca 600 c magmatic to epithermal 250 c conditions during progressive cooling exhumation and mixing with meteoric sources at shallow crustal conditions ca 7 3 km the re os molybdenite dating constrains the high grade mo ore formation at ca 29 28 ma attesting for the intimate linkage between the main mo mineralisation and the acidic magmatic phase in the area the rb sr geochronology of the potassic sodic alteration zones confirms the two stage magmatic mineralisation scenarios overlapping within errors with the results obtained from the u pb zircon geochronology and constraining the formation of the potassic sodic and phyllic alteration at ca 33 and 28 ma respectively our results document an uncommon scenario of two stage porphyry mo mineralisation associated with intensive late stage carbonate precipitation and achieved during a long lasting and multiphase magmatic pulses of oligocene age we highlight the dominant role of acidic fluid neutralisation for further ore enrichment during polyphase magma intrusion as the dominant factor controlling the mo mineralisation in the skmd comparison at a regional scale indicates that parameters such as longevity of magma supply progressive magma crystallization differentiation and the presence of a possible pre enriched crustal material should be considered responsible for the mo endowment in the udmz

effect of el nino southern oscillation on the dynamical thermal and chemical structure of the middle atmosphere 1 a simulation of the middle atmosphere is presented using a general circulation model gcm forced with observed sea surface temperature for the period 1950 2000 the gcm extends to the lower thermosphere and reproduces realistic dynamical and temperature distributions the period contains several el nino and la nina events which are identified using the nino3 index composite anomalies of relevant meteorological fields are obtained by stratifying the northern winter season according to the nino3 index these anomalies have the structure of vertically propagating planetary waves extending from the troposphere to the mesosphere circulation anomalies in the middle atmosphere are accompanied by large temperature anomalies that are of opposite sign in the stratosphere and mesosphere the former being warmer and the latter colder during el nino events near the summer mesopause changes in momentum deposition by parameterized gravity waves results in warming during el nino detailed statistical analysis is used to determine the significance of these anomalies a chemical transport simulation is carried out using output from the gcm it shows that when the lower stratosphere is colder as during la nina events some ozone depletion takes place conversely when the lower stratosphere is warmer and more disturbed as is the case during el nino events heterogeneous chemical processes are inhibited

environmental geochemistry of rare earth elements in cu porphyry mine tailings in the semiarid climate conditions of sarcheshmeh mine in southeastern iran abstract sarcheshmeh mine is one of the largest oligo miocene porphyry cu deposits in the world it is located in the kerman cenozoic magmatic arc in southeastern iran this paper discusses the geo environmental behavior of rare earth elements rees in the sarcheshmeh dammed tailing pond situated in semiarid climate for this purpose solid and water samples were collected to consider 1 weathering oxidation reactions and upward migration of soluble elements 2 super saturation and formation dissolution of the secondary evaporative phases 3 hydro geochemical changes of the surface and groundwater resources 4 flotation of the cu sulfide ore and tailing management strategies the mean values of the rees for fresh and weathered tailings and the evaporative phases were 113 0 103 7 and 74 6 mg kg respectively when compared with the fresh and weathered tailings the evaporative phases showed significant enrichment of hrees and a well depleted pattern of lrees except for that of eu this geochemical pattern suggests a higher solubility and mobility potential of hrees and eu compared with lrees resulting in good fractionation and enrichment of these elements in the surface evaporative layer formed on top of the weathered tailings the water samples showed a range of hydro geochemical features under acidic ph of 2 5 to 4 7 near neutral ph of 6 4 to 7 9 alkaline ph of 8 to 10 and highly alkaline ph 10 conditions the maximum concentration of rees was observed in the acidic waters produced by the weathered tailings after rainfall rees of 489 to 1903 g l although rees decreased as the ph value increased the general trend was compatible with the highest concentration of hrees rather than lrees the speciation calculations indicate that lnso4 ln so4 2 and ln3 are the primary forms of dissolved rees at acidic and near neutral ph and the dominant species was lnso4 lnco3 40 78 ln co3 2 31 68 and lnso4 31 07 were the dominant species under alkaline conditions at high alkaline ph the speciation pattern changed to lnoh2 53 15 ln co3 2 44 88 and lnco3 2 61 where ln denotes lanthanide based on the results and considering previous works it appears that ionic potential plays an important role in the geo environmental behavior of rees of adsorption tendency mobility potential and ionic substitution

el nino modoki and its possible teleconnection 1 using observed data sets mainly for the period 1979 2005 we find that anomalous warming events different from conventional el nino events occur in the central equatorial pacific this unique warming in the central equatorial pacific associated with a horseshoe pattern is flanked by a colder sea surface temperature anomaly ssta on both sides along the equator empirical orthogonal function eof analysis of monthly tropical pacific ssta shows that these events are represented by the second mode that explains 12 of the variance since a majority of such events are not part of el nino evolution the phenomenon is named as el nino modoki pseudo el nino modoki is a classical japanese word which means a similar but different thing the el nino modoki involves ocean atmosphere coupled processes which include a unique tripolar sea level pressure pattern during the evolution analogous to the southern oscillation in the case of el nino hence the total entity is named as el nino southern oscillation enso modoki the enso modoki events significantly influence the temperature and precipitation over many parts of the globe depending on the season the impacts over regions such as the far east including japan new zealand western coast of united states etc are opposite to those of the conventional enso the difference maps between the two periods of 1979 2004 and 1958 1978 for various oceanic atmospheric variables suggest that the recent weakening of equatorial easterlies related to weakened zonal sea surface temperature gradient led to more flattening of the thermocline this appears to be a cause of more frequent and persistent occurrence of the enso modoki event during recent decades

metal content and p t evolution of co2 bearing ore forming fluids of the haftcheshmeh cu mo porphyry deposit nw iran abstract the haftcheshmeh cu mo porphyry deposit is located in the nw part of the arasbaran metallogenic magmatic zone nw iran ore mineralisation is generally hosted within the gabbro diorite and granodiorite porphyry stocks presenting various types of hydrothermal quartz veins and veinlets associated with potassic to sericitic alteration stage i corresponds to barren quartz k feldspar biotite anhydrite veins a veins with minor metal sulphides pyrite chalcopyrite surrounded by k feldspar and biotite halos related to potassic alteration stage ii is described with quartz molybdenite chalcopyrite pyrite bornite magnetite hematite biotite veins predominantly occurring in the potassic alteration halos b veins stage iii shows pyrite quartz chalcopyrite molybdenite galena sphalerite associated with sericitic alteration halos d veins the coexistence of halite saturated aqueous rich and low salinity vapour rich fluid inclusions in the h2o nacl co2 system is evidence of fluid boiling in each alteration mineralising stage this process was subsequently followed by meteoric water input diluting the co2 bearing ore forming fluid la icpms data of fluid inclusions associated with the successive stages reveal elevated na k fe mn cu and mo content the metal content of fluid inclusions of stages ii and iii is in large part due to accidentally trapped minerals molybdenite and chalcopyrite started precipitating between stages i and ii from a metal poor fluid the long duration 1 ma of the magmatic hydrothermal activity and associated co2 fluxes and repeated fluid boiling events lead to ore deposition at temperatures of 450 to 250 c and at depths between 3 0 and 1 0 km from near lithostatic to near hydrostatic conditions

signal of central pacific el nino in the southern hemispheric stratosphere during austral spring using era interim and modern era retrospective analysis for research and applications reanalysis data sets we investigated the effects of the central pacific cp el nino on the southern hemispheric sh stratosphere particularly during the austral spring sh stratosphere warming is at a maximum in september rather than in november and december as suggested by previous studies sh stratospheric temperature anomalies become significant beginning in july and reach a peak of approximately 4 k in september reflecting a weakened sh vortex and a strengthened sh stratospheric brewer dobson circulation the anomalous eliassen palm flux and its divergence in the sh midlatitudes are most significantly enhanced in august leading to the sh maximum stratospheric temperature anomalies approximately 1 month later in the middle latitudes of the sh the poleward and upward propagation of enhanced planetary waves pws during the austral winter july september causes anomalous sh polar warming and tropical cooling in the stratosphere the wave number 1 wn1 pattern is responsible for pw anomalies in august whereas the wn2 pattern is responsible for those in september eddy heat flux during cp el nino is also anomalously enhanced in extratropical sh stratosphere in both august and september and subsequently weaken during the following months

pb isotopic compositions of some zn pb deposits and occurrences from urumieh dokhtar and sanandaj sirjan zones in iran abstract this study reports pb isotope ratios of galena pbs sampled from some zn pb deposits and occurrences n 18 within two major structural provinces of iran the sanandaj sirjan zone ssz and urumieh dokhtar zone udz regardless of the nature of the host rock and ore type the pb isotopic data plot in distinct isotopic fields according to their geographic situation which suggest that the structural terranes had an important control on the lead isotope compositions the zn pb deposits in the udz record distinctly higher 206pb 204pb and 208pb 204pb ratios compared to those within the ssz both zones however have radiogenic 207pb 204pb ratios 15 55 suggesting a dominant input of pb from crustal sources in thorogenic 208pb 204pb vs 206pb 204pb and uranogenic 207pb 204pb vs 206pb 204pb plots the pb isotope data define two linear arrays which may be attributed to mixing between mantle like end members and at least two distinct crustal sources characterized by high u pb and th u ratios in plumbotectonic discrimination diagrams the samples plot proximal to the orogenic curve which again supports interaction between crustal and mantle reservoirs however both neo tethys subduction and in particular mesozoic and tertiary orogenic activities seem to have played important roles in remobilizing pb and forming zn pb deposits in ssz and udz respectively the similarity of pb isotopic compositions between udz deposits and those for previously reported eocene volcanics demonstrates that long lived and widespread hydrothermal activity promoted remobilization of lead from the crust the latter occurred subsequent to neo tethys lithosphere subduction in the tertiary and continued subsequent the collision of the iranian and arabian plates in the miocene

recycling of orogenic arc crust triggers porphyry cu mineralization in kerman cenozoic arc rocks southeastern iran pre collisional eocene oligocene arc diorites quartzdiorites granodiorites and volcanic equivalents in the kerman arc segment in central iran lack porphyry cu mineralization and ore deposits whereas collisional middle late miocene adakite like porphyritic granodiorites without volcanic equivalents host some of the world s largest cu ore deposits petrological and structural constraints suggest a direct link between orogenic arc crust evolution and the presence of a fertile metallogenic environment ore hosting kuh panj porphyry intrusions exhibit high sr 400 ppm low y 20 no negative eu anomalies eu eu 1 and relatively non radiogenic sr isotope signatures 87sr 86sr 0 7042 0 7047 relative to eocene oligocene granitoids mainly sr 12 la yb 15 eu eu 1 87sr 86sr 0 7053 0 7068 trace element modeling indicates peridotite melting for the barren eocene oligocene intrusions and a hydrous garnet bearing amphibolite source for middle late miocene ore hosting intrusions the presence of garnet implies collisional arc crustal thickening by shortening and basaltic underplating from about 30 35 to 40 45 km or 12 kbar the changes in residual mineralogy in the source of eocene to miocene rocks in the kerman arc segment reflect probing of a thickening arc crust by recycling melting of the arc crustal keel underplating of cu and sulfur rich melts from fertile peridotite generated a fertile metallogenic reservoir at or near the crust mantle boundary and dehydration melting under oxidizing conditions produced syn and post collisional ore hosting intrusions while the lack of post collisional volcanism prevented the venting of volatiles to the atmosphere from sulfur rich and oxidized adakitic magmas

the role of linear interference in the annular mode response to extratropical surface forcing abstract the classical problem of predicting the atmospheric circulation response to extratropical surface forcing is revisited in the context of the observed connection between autumnal snow cover anomalies over siberia and wintertime anomalies of the northern annular mode nam previous work has shown that in general circulation model gcm simulations in which autumnal siberian snow forcing is prescribed a vertically propagating rossby wave train is generated that propagates into the stratosphere drives dynamical stratospheric warming and induces a negative nam response that couples to the troposphere important questions remain regarding the dynamics of the response to this surface cooling it is shown that previously unexplained aspects of the evolution of the response in a comprehensive gcm can be explained by examining the time evolution of the phasing and hence the linear interference between the rossby wave response and the background climatological stationary wave when the wave response a