rare earth element geochemistry of fluorite carbonate deposits in western montana u s a abstract the fluorite carbonate quartz deposits of mineral missoula and ravalli counties in western montana u s a at one time described as carbonatitic have recently been shown to be hydrothermal in origin based on chemical o and sr isotope and field studies we report the results for rare earth elements ree in the fluorite and carbonate minerals and discuss the implications for their origin fluorite from lime gulch white cloud swallow spar wilson gulch and snowbird deposits exhibits ree chondrite patterns with a pronounced enrichment in the middle ree mree highly depleted light ree lree and slightly depleted lu often accompanied by a similar small depletion in yb la is depleted relative to sm by an order of magnitude calcite is also mree enriched although la is not as depleted relative to sm as in the associated fluorite dolomite does not show la depletion relative to sm calcite and dolomite have negative eu anomalies whereas some of the fluorite does not ree patterns for the fluorite and carbonates are typical of those from other hydrothermal deposits reported in literature chemical zonation caused by complexation of mree and hree with carbonate and fluoride ions and a high degree of ree fractionation apparently produced the ree distribution patterns observed for these deposits

regional variations in fluid formation and metal sources in mvt mineralization in the pennine orefield uk implications from rare earth element and yttrium distribution sr nd isotopes and fluid inclusion compositions of hydrothermal vein fluorites abstract the pennine orefield is one of the most important ore fields for pb zn ba f mineralization in great britain it is subdivided into the northern pennine orefield npo consisting of the alston and askrigg blocks and the southern pennine orefield spo the alston block is underlain by the early devonian weardale granite and the askrigg block by the coeval wensleydale granite the potential relationship between the batholiths and the mineralization is a matter of debate we here studied the rare earth elements and y rey geochemistry sr nd isotopes and fluid inclusion fi compositions of fluorites from the two structural blocks in the npo and found that the fluorite mineralization in these blocks differ substantially the rey in askrigg fluorites show features that are characteristic for leaching of adjacent lower carboniferous limestones in contrast alston fluorites have significantly higher rey concentrations lack reysn limestone signatures and show a decoupling of redox sensitive eu from its trivalent rey neighbours neodymium isotopes indicate a similar crustal source of rey in both blocks but higher rey concentrations and lower y ho ratios suggest lower carboniferous shales as potential rey source in the alston block the fluids that precipitated the alston fluorites experienced temperatures 250 c prior to mineral formation as evidenced by eu geothermometry fluorite formation however occurred at much lower temperatures as suggested by homogenization temperatures in fi that fall within ranges of 105 159 c in alston and 99 160 c in askrigg fluorites mineralization of the mississippi valley type usually lack association with igneous activity we show that some of the fluids responsible for the npo mineralization were influenced by magmatic sources the rey systematics in alston fluorites may be linked to an interaction of the permian age whin sill dolerite with the basement granite which heated fluids and focussed fluid flow into the overlying sedimentary rocks in the askrigg block where such a dolerite intrusion was not described fluorites lack any positive eusn anomalies indicating that these fluids had never been subjected to temperatures exceeding 200 250 c

rare earth and minor element distribution and petrographic features of fluorites and associated mesozoic limestones of northwestern sicily abstract the casual discovery of a fluorite mineralization in mesozoic limestones of northwestern sicily has suggested a geochemico petrographic investigation of its possible origin the fluorite has been found associated with calcite barite quartz and iron oxides and is present in varieties of five different colours the petrographic study after outlining the features of the host rock shows the textural relationships between the mineral and its associated phases the geochemical behaviour of mg mn fe and sr is more clearly identified among the minor elements determined in the fluorites and in the limestones associated with fluorite and even in the non mineralized limestones ree distribution patterns strongly emphasize the hydrothermal origin of the fluorite mineralization most of the fluorite samples indicate that the solution from which it crystallized interacted with the limestone fluorite and calcite did not crystallize from the same solution

thermal and chemical evolution of fluids during fluorite deposition in the zaghouan province north eastern tunisia several f pb zn and ba deposits are located in the province of zaghouan in north eastern tunisia they are hosted in lower liassic or upper jurassic reef limestones and the overlying condensed carixian phosphatic limestones and campanian marls respectively the mineralization occurs in three types of orebodies stratiform replacement heaps and lenses jebel stah and hammam zriba breccia fillings and dissolution void fillings sidi taya and lodes jebel oust more than one generation of fluorite is observed in the stratiform deposits microthermometric analyses of the inclusion fluids observed in fluorite and quartz show that the economic concentrations of fluorite have deposited from moderate to highly saline 12 22 5 wt nacl equivalents hydrothermal 110 160 c mineralizing fluids at the center jebel stah sidi taya and to the east of the province hammam zriba late remobilizations observed in the stratiform deposits are related to the circulation of a warmer up to 185 c but less saline 10 wt nacl equivalents fluid jebel stah and more saline 12 22 wt nacl equivalents fluid hammam zriba the highest temperature up to 250 c and salinity 32 34 wt nacl equivalents are observed to the west of the province of zaghouan jebel oust less saline 3 6 wt nacl equivalents and moderately hot to hot fluids up to 220 20 c and rich in gaseous co2 invade most of the ore deposits in later stages and give rise to the massive quartz within fractures at jebel stah chemical analyses of the fluids extracted from the inclusions occuring in fluorite show compositions dominated by the presence of na ca2 and cl ionic species and allow the mean temperature of the fluids in the source reservoir to be estimated as 275 25 c the circulation of the ore forming fluids is triggered by a regional tectonic extensional phase which occurs within the post jurassic to ante miocene time interval the deposition of the economic concentrations of fluorite resulted from the decrease in pressure and temperature of the hydrothermal brines jebel oust along with the increase in the dissolved calcium activity jebel stah and sidi taya or a decrease in salinity due to the mixing with a hot less saline and na poor ca rich fluid hammam zriba the mineralogical associations caf2 pbs zns baso4 hosted within carbonate rocks the temperatures and the salinities of the fluids that gave rise to the more important ore deposits 110 160 c and 12 22 5 wt nacl equivalents their composition na ca cl and the molar ratios between the major ionic species as well as the presence of liquid hydrocarbons in the mineralizing fluids show that the ore deposits of the province of zaghouan belong to the carbonate hosted f pb zn ba mississippi valley type deposits

the mean summertime circulation along australia s southern shelves a numerical study abstract for the first time a high resolution regional model is developed for the slope and shelf circulation within the great australian bight and for the gulfs region of south australia the results indicate the extent nature and dynamical interaction of a variety of circulation features that are most likely to be important for the region in particular the positive wind stress curl south of australia leads to an equatorward sverdrup transport in the deep ocean westward flinders current along the slope and upwelling of the 600 m deep permanent thermocline the wind stress curl also leads to a seaward topographic sverdrup transport within the wide sloping shelf of the bight and results in an anticyclonic gyre that is intensified off the eyre peninsula and reduced in magnitude by the joint effect of baroclinicity and topographic relief in the western half of the bight the seaward surface ekman and topographic transports are shown to converge with the onshore component of the flinders current lea

rare earth element systematics in scheelite from hydrothermal gold deposits in the kalgoorlie norseman region western australia scheelite cawo 4 is a widespread accessory mineral associated with hydrothermal veins in the archean gold deposits of the kalgoorlie norseman region of western australia rare earth element ree and other trace element abundances in scheelite have been determined in situ by excimer laser ablation inductively coupled plasma mass spectrometry ela icp ms in order to constrain the composition and sources of the mineralizing fluids the scheelites can be grouped according to the two distinct types of chondrite normalized ree ree n patterns which they exhibit hump shaped type i and flat type ii type i scheelites have higher total and na concentrations than type ii samples and can be further subdivided into type ia which has maximum ree n concentrations between sm and gd and type ib which has maximum ree n concentrations displaced toward dy type i scheelites are dominant at coolgardie kalgoorlie and kambalda whereas type ii samples are most abundant at norseman a few scheelite grains exhibit both type i and type ii characteristics the two types of ree n patterns with different na abundances suggest that the trivalent ree substituted into the ca site of scheelite by two different mechanisms 2ca super 2 ree super 3 na super for the type i scheelites and 3ca super 2 2ree super 3 ca where ca is a ca site vacancy for the type ii samples the parabolic shape of ree n patterns in the type i scheelites can be used to calculate the ionic radius of the ree super 3 that preferentially substitutes into the scheelite structure when type i ree patterns are normalized to account for variations in light ree abundance the average value obtained is 1 060 aa for type ia and 1 055 aa for type ib scheelites these values are smaller than the value of 1 12 aa for the ca site but are in excellent agreement with the value of 1 06 aa predicted by the coupled na super ree super 3 substitution mechanism assuming size as well as charge compensation this result implies that na super and ree super 3 substitute into adjacent sites in the crystal structure of type i scheelites in contrast the incorporation of ree into type ii scheelites appears to be independent of size it is suggested that in this type of scheelite involvement of a ca site vacancy relaxes the size constraint on the substitution of the ree super 3 the influence of ree speciation in the hydrothermal fluid on the systematic difference between scheelite fluid partition coefficients for type i and ii scheelites is of secondary importance compared with crystal chemistry effects the distinctive ree n patterns and high na contents of type i scheelites imply that they crystallized from hydrothermal fluids with higher na activities than those that formed type ii samples type i scheelites exhibit no changes in the size of the eu anomaly with ree concentration implying a predominance of eu super 3 and crystallization under relatively oxidized conditions type ii scheelites have variable eu anomalies and trivalent ree concentrations and thus appear to contain mostly eu super 2 and to have formed under reduced conditions type ia and ii scheelites have ce lu n 1 and are interpreted to have crystallized from light ree enriched fluids whereas type ib scheelites with ce ln n 1 formed from light ree depleted fluids the fluid characteristics inferred from the ree and trace element systematics in the scheelites can be attributed to the rock types and estimated physical conditions in the kalgoorlie norseman region at the time of hydrothermal activity high na activities are consistent with buffering of fluids by greenschist facies mafic rocks whereas low fluid na activities are a product of fluid rock reactions at higher metamorphic grades oxidized fluids are consistent with near surface derivation whereas reduced fluids are indicative of generation at elevated temperatures and pressures the range and distribution of fluid ce ln n ratios are similar to those of the major rock types in the region

pb zn deposits and salt bearing diapirs in southern europe and north africa many diapirs with triassic evaporite successions in southern europe and north africa are accompanied by strata bound pb zn mineral deposits these are of two types 1 epigenetic mineralization filling cavities exhibiting analogies with mississippi valley type deposits and 2 syndiagenetic mineralization in sediments rich in organic materials this second type is very similar to the so called volcanic exhalative type in most of these ore deposits diapirism seems to be a determining factor in the development of base metal concentrations diapir growth can be divided into four distinct stages initiation ascent piercement and subsequent deformation study of north african and southern european deposits has led to a genetic model of diapir emplacement and associated pb zn mineralization the source of these metals is unknown the transport of the metals is provided or facilitated by the brine from adjacent triassic evaporites deposition of sulfides occurs where the deep fluids meet the upper beds these deposits can be remobilized with each new phase of diapir growth

a northern boundary current along australia s southern shelves the flinders current 1 south of australia the monthly mean wind stress curl is positive during both summer and winter and leads to ekman pumping and downwelling throughout the region sverdrup dynamics indicates that this downwelling should lead to a northward transport of around 5 10 sv 1 sv 10 m3 s 1 classical arguments for western boundary currents are adapted to show that this transport should be deflected into an upwelling favorable boundary current that flows from east to west along australia s southern shelves the flinders current support for this proposition is obtained from results of the ocean circulation and climate advanced modelling project occam sverdrup transports and limited observations for the region in addition the occam results show that the northward transport leads to upwelling at depths below 400 m and that the flinders current 1 intensifies from victoria to western australia transport 8 sv with speeds up to 15 cm s 1 2 can extend from the surface to depths of 800 m and 3 is found during both summer and winter during winter the winds are downwelling favorable and lead to a coastal current that flows from west to east and opposes the flinders current further support for the origin and nature of the flinders current is obtained from simple numerical experiments made using a rectangular domain and idealized representations of the summer and winter wind stress

the ribeira fluorite district southern brazil geological and geochemical ree sm nd isotopes characteristics the origin and evolution of different ore deposits grouped in the same district are often complex and may involve inheritance from crustal or mantle geochemical anomalies remobilization of former ore deposits and a polyphase hydrothermal history localized in a proterozoic basement in the parana state the ribeira fluorite district is such an example composed of three deposit types with distinct geological and geochemical characters emplaced at different periods from the late proterozoic to the cretaceous they are roughly aligned along a belt nearly 10 km in width and 50 km in length the southern boundary of which is a transcurrent fault two main ore facies are present 1 microcrystalline ore 0 1 mm grains and 2 macrocrystalline ore with a grain size of several millimetres the former results from the replacement of metalimestones or internal karstic sediments and the latter from microcrystalline ore dissolution and pore precipitation or recrystallization at least two different groups of source rocks can be proposed for the trapped ree in caf2 1 fluorite samples associated with the mato preto carbonatitic rocks display a slightly negative nd compatible with a mantle source and a ree pattern with the higher ree and la yb ratio in the district 2 other fluorites have a strongly negative nd 14 to 20 which indicates a crustal source that fluorine and ree have the same source is possible in strata bound and fracture filling deposits but is doubtful at mato preto the only economic fluorite deposit associated with carbonatite rocks in brazil this occurrence within a precambrian fluorite belt suggests that remobilization of a former strata bound deposit was a more significant metallogenic process than magmatic differentiation

gangue mineral 87 sr 86 sr ratios and the origin of mississippi valley type mineralization the 87 sr 86 sr ratio measurements in mississippi valley type gangue minerals and host marine carbonates ranging in age from upper cambrian to mississippian show that in northwestern ohio where the mineralization is sparse the minerals precipitated from fluids in local isotopic equilibrium with the host carbonates in which the minerals were emplaced in contrast most gangue minerals from districts of major mineralization in illinois kentucky virginia and tennessee contain strontium with higher 87 sr 86 sr ratios than the carbonate hosts and appear to have crystallized from fluids containing strontium from silicate minerals in the sedimentary succession no evidence has been found for a magmatie component in the ore fluid strontium data from elmwood tennessee show that the early ore fluids like those of northwestern ohio were in isotopic equilibrium with the host carbonates but that they were mixed with and displaced by introduced fluids containing more radiogenic strontium these findings are consistent with the two fluid mixing model for the mississippi valley mineralization where a fluid indigenous to the host carbonates and containing reduced sulfur was mixed with introduced fluids analogous to metal bearing and low sulfide oil field brines with an extensive history of chemical exchange with clays and other silicate minerals in the sedimentary succession

do east australian current anticyclonic eddies leave the tasman sea using satellite altimetry and high resolution model output we analyze the pathway of large long lived anticyclonic eddies that originate near the east australian current eac separation point we show that 25 30 of these eddies propagate southward around tasmania leave the tasman sea and decay in the great australian bight this pathway has not been previously documented owing to poor satellite sampling off eastern tasmania as eddies propagate southward they often stall for several months at near constant latitude along the pathway eddies become increasingly barotropic eddy intensity is primarily influenced by merging with other eddies and a gradual decay otherwise surface temperature anomaly associated with anticyclonic eddies changes as they propagate while surface salinity anomaly tends to remain relatively unchanged as they propagate

mineral deposits of turkey in relation to tethyan metallogeny implications for future mineral exploration the tethyan metallogeny of turkey shaped by the interplay between subduction collision postcollision and rifting processes is mainly associated with late cretaceous to cenozoic volcanoplutonic and ophiolitic rocks a wide spectrum of ore deposits is represented from those occurring in island arcs to those associated with continental settings though turkey has been one of the leading producers of chromite the country is an emerging producer of precious and base metals this assessment of the metallogeny of turkey is based on a comprehensive gis database compilation that contains known mineral deposits and prospects with relevant descriptive data the data set contains information on major deposit types of economic importance such as porphyry skarn epithermal including both high and low sulfidation polymetallic volcanic associated massive sulfide vms deposits including both kuroko and cyprus types podiform chromite lateritic nickel carbonate hosted lead zinc with nonsulfide zinc including sedimentary exhalative sedex and mississippi valley type mvt karstic and lateritic bauxite orogenic gold including both mesothermal and listwanite hosted types and placer deposits well known deposit types that are less well represented in the database include sediment hosted cu carlin type gold iron oxide copper gold iocg and detachment fault related gold systems exploration programs in the last two decades have started to reveal the true mineral potential of the country turkey is an underexplored country by today s standards with a large prospective area with a wide spectrum of mineral deposits reflecting the diverse geological environments that are present turkey is the least well explored portion of the tethyan belt which hosts au and cu endowments comparable with the andes and the southwest pacific metallogenic belts

the origin of the calcites from pb zn veins in the harz mountains federal republic of germany abstract studies of the ree distribution in calcites from hydrothermal banded pb zn mineralizations as well as in calcites from pelitic and psammitic unmetamorphosed rocks and magmatites of the harz mountains revealed that the calcite of the banded ores crystallized from hybrid magmatic metamorphic solutions these were rather rich in ree3 fe3 and probably zn2 and pb2 ion concentrations the absence of any negative eu anomalies points to oxidizing conditions the sulphides have crystallized from a different solution it is suggested that the necessary hs rich solutions stem from near surface hydrothermal convection cells set up by nearby granitic intrusions the alternating deposition of calcite and sulphide banded ores may be explained by assuming that farther away from the intrusions the hs rich solutions were intermittedly admixed with the hybrid fluids this caused a decrease in temperature an interruption of calcite deposition and sulphide mineralization near the intrusion continuous mixing of these two fluids became more common and consequently banded ores are rather rare

eddy variability and energetics from direct current measurements in the antarctic circumpolar current south of australia two year time series measurements of current velocity and temperature in the subantarctic front saf south of australia from 1993 to 1995 provide estimates of eddy fluxes of heat and momentum across the antarctic circumpolar current acc and further insight into the variability of the acc the saf was found to be an energetic meandering jet with vertically coherent fluctuations varying on a timescale of 20 days with typical amplitude 30 cm s21 at 1150 dbar a daily varying coordinate frame that follows the direction of flow allowed mesoscale variability of the saf to be isolated from variability due to meandering of the front and proved very successful for examining eddy fluxes vertically averaged cross stream eddy heat flux was 11 3 kw m 22 poleward and significantly different from zero at 95 for fluctuations in the 2 90 day band zonally integrated this eddy heat flux 50 9 pw is more than large enough to balance heat lost south of the polar front and is as large as cross saf fluxes found in drake passage cross stream eddy momentum fluxes were small not significantly different from zero and of indeterminate sign but tending to decelerate the mean flow a relationship between vertical motion and meander phase identified in the gulf stream was found to hold for the acc eddy kinetic energy levels were similar to those in drake passage and southeast of new zealand eddy potential energy was up to an order of magnitude larger than at other acc sites most likely because meandering of the front is more common here baroclinic conversion was found to be the dominant mechanism by which eddies grow south of australia typical eddy growth time is estimated to be 30 days approximately twice as fast as in drake passage consistent with eddy energy growing rapidly downstream

tracing element sources of hydrothermal mineral deposits ree and y distribution and sr nd pb isotopes in fluorite from mvt deposits in the pennine orefield england fluorite from mississippi valley type mvt deposits in the south pennine orefield england displays significantly different distributions of rare earths and yttrium rey compared to fluorite from similar mvt deposits in the north pennine orefield samples from the south pennine orefield display negative ce and positive gd and y anomalies but lack any eu anomaly indicating that the rey were mobilized from relatively pure marine sedimentary carbonates in marked contrast fluorite from the north pennine orefield lacks any ce and gd anomalies but shows a pronounced positive eu anomaly suggesting that the rey were provided by different source rock s that the mineralizing hydrothermal fluid had experienced higher temperatures prior to fluorite precipitation and that it was derived from deeper crustal levels in the north compared to the south the isotopic composition of sr in blue john fluorite from the south pennine orefield suggests that sr was mobilized from lower carboniferous tournaisian limestones whereas pb isotopes suggest that in contrast to rey and sr pb was derived from aluminosilicate rocks neither nd nor sr or pb isotopes can be used to radiometrically date the formation of blue john fluorite all isotope systems studied indicate that the limestone host rock of this fluorite mineralization did not contribute to the trace element budget of the hydrothermal fluid our results show that different solutes in a natural water hydrothermal fluid groundwater etc may be derived from different sources and that the study of a small set of elements or isotope ratios may not provide full insight into the genesis or history of a mineralization or a hydrothermal fluid our data provide evidence for the uncoupling of sr nd and pb during fluid rock interaction and fluid migration and show that the use of plots such as 87sr 86sr vs end to learn about mixing relationships as is commonly done in igneous geochemistry is unreliable when applied to natural waters and their precipitates

fluorite 87sr 86sr and ree constraints on fluid melt relations crystallization time span and bulk dsr of evolved high silica granites tabuleiro granites santa catarina brazil abstract the evolved high silica tabuleiro granites within the early paleozoic santa catarina composite massif pelotas batholith southern brazil are characterized by the presence of euhedral to subeuhedral accessory fluorite and geochemical features typical of topaz rhyolites and related a type granites sr isotopes and ree data of the tabuleiro granites and their accessory fluorite are used to constrain fluid melt relations crystallization time span and bulk crystal melt sr partition coefficient d sr correlations involving ree eu eu rb sr sr and 87 sr 86 sr in fluorite and fluorite host granites show that fluorite records the differentiation trend of the host tabuleiro granites ree normalized patterns and eu eu relations in fluorite bearing granites indicate that fluorite forms after the crystallization of the quartzo feldspathic framework in residual melts the tabuleiro accessory fluorites yield high and variable 87 sr 86 sr ratios between 0 72334 and 0 8192 these ratios are neither the result of fluorite precipitation from a fluid nor sr isotopic resetting they result from 87 rb decay in fluorine rich high rb sr melts evolved by fractional crystallization in a magmatic system with a long crystallization time span melt residence times of 300 to 700 ka and d sr of 4 7 to 6 0 are necessary to yield the high fluorite 87 sr 86 sr ratios these results are compatible with those deduced elsewhere from high silica rhyolitic volcanic equivalents

the role of evaporites in the genesis of base metal sulphide mineralisation in the northern platform of the pan african damara belt namibia geochemical and fluid inclusion evidence from carbonate wall rock alteration the otavi mountain land is a base metal sulphide ore province in northern namibia where deposits are hosted by platform carbonates of the otavi group in a foreland fold and thrust belt on the northern edge of the pan african damara belt deposits have been classified as the berg aukas or tsumeb types based on differences in ore association stratigraphic position and geochemistry of ores and gangue carbonates mineralisation at these deposits is accompanied by carbonate alteration in the form of dolomite and calcite veins carbonate recrystallisation calcitisation and carbonate silicification based on cathodoluminescence imaging trace and rare earth element ree o and c isotope and fluid inclusion data a series of carbonate generations constituting wall rock alteration around the tsumeb and kombat tsumeb type and berg aukas berg aukas type deposits was established similar data obtained on the recently discovered khusib springs deposit indicate a strong affinity to tsumeb type deposits tsumeb type deposits are distinguished from berg aukas type deposits by having trace element and ree concentrations that are significantly higher in the alteration products compared to the carbonate host rocks only around tsumeb type deposits a relative enrichment in light ree is noted for the hydrothermal carbonate generations that are cogenetic with the main stage of mineralisation microthermometric results from fluid inclusions in carbonate alteration phases and associated quartz indicate relatively high salinity 17 23 wt nacl equivalent for the main mineralising and subsequent sulphide remobilisation stages at the deposits investigated estimated mineralisation temperatures are significantly higher for tsumeb type deposits 370 405 c with early sulphide remobilisation in tsumeb at 275 c whereas they are lower at berg aukas up to 255 c fluid inclusion leachate analysis suggests that most of the observed salinity can be ascribed to dissolved predominantly ca and mg carbonates and chlorides with subordinate nacl na cl br leachate systematics indicate a derivation of the fluid salinity from the interaction with evaporitic rocks en route tsumeb type mineralisation is interpreted to be derived from fluids expelled during pan african orogeny in the more intensely deformed internal zones of the damara belt further south when the high salinity fluids reached the carbonate platform after having scavenged high concentrations of base metals base metal sulphide precipitation occurred in zones of high porosity provided by karst features in the carbonate sequence results obtained for the berg aukas type deposits emphasise their derivation from basinal brines similar to mississippi valley type deposits and confirm that mineralisation of the berg aukas and tsumeb types are both spatially and temporally distinct

discovered and undiscovered gold endowment of turkey a quantitative mineral resource assessment using gis and rank statistical analysis an assessment of the discovered and undiscovered gold endowment of turkey a prolific sector in the tethyan metallogenic belt is developed from a comprehensive geographic information system database containing 402 gold deposits and prospects the majority of the gold deposits and prospects are epithermal porphyry volcanic associated massive sulfides orogenic gold and skarn systems these five major deposit types form more than 90 of the known gold deposits and prospects just 87 corresponding to 21 6 of the deposits and prospects in the data set have current calculated gold reserve and or resources containing a total of 54 885 moz au current gold reserves of the country are 21 447 moz constituting 39 1 of the total gold resources of which 17 1 moz gold are contained in four deposits out of these 87 deposits and prospects only 27 contain significant gold reserve and or resources defined as equal to or more than 0 32 moz or 10 tons au and contain 91 8 of the total gold endowment of the country the cumulative frequency distribution model of the gold endowment of turkey abides by log normal distribution observed and estimated 10th 50th median and 90th percentiles of the data are 0 0046 moz 0 0045 moz estimated 0 1030 moz 0 0875 moz and 1 4969 moz 1 6938 moz respectively the 99th percentile of the data is 7 6444 moz 18 9636 moz the arithmetic mean of the known gold endowment is 0 657 moz and the swanson mean size is 0 492 moz the arithmetic mean of the 27 significant gold deposit or prospects is 1 94 moz zipf s law estimates of the undiscovered residual gold resources of turkey are based on the current size of the largest rank 1 gold deposit of turkey which is the kisladag porphyry deposit that has 17 481 moz gold endowment including past production zipf s law estimates a total of 88 261 moz natural or total gold endowment 57 133 moz or 65 of which has already been found this predicts at least 31 128 moz residual or undiscovered gold resources to be found in turkey though the lack of full delineation of the rank 1 deposit kisladag means that this figure is very conservative

the 5500 km long boundary flow off western and southern australia 1 the path of the shelf edge flow off southwestern australia is documented using results from satellite altimetry and sea surface temperature sst and a climatogical in situ analysis during austral winter a continuous current is shown to extend from its origin at north west cape to the southern tip of tasmania a distance of 5500 km satellite sst observations and surface buoy tracks confirm the location and continuity of the current trajectory while the leeuwin current is forced by the strong alongshore pressure gradient associated with the meridional portion of the western australian coastal boundary our results suggest that the essentially zonal shelf edge flow along the southern australian coast arises from the setup of coastal sea level by onshore ekman flow driven by the winter westerly wind and possibly a further alongshore pressure gradient the timing of these two different forcing mechanisms means that the west coast pressure gradient delivers the leeuwin current to the south coast just as the winds reverse and are thus able to maintain the eastward passage of the current the shelf edge flow consists of two main water masses a low salinity warm water type of tropical origin associated with the leeuwin current and a high salinity warm water inflow formed on the western end of the great australian bight continental shelf a naming convention is proposed the leeuwin current representing flow from north west cape to the great australian bight gab the south australian current between the eastern gab and western bass strait and the zeehan current off western tasmania

the genesis of fluorspar hydrothermal deposits at montroc and le burc the tarn as deduced from fluid inclusion analysis the genetic conditions of two fluorspar hydrothermal deposits are determined by the study of fluid inclusions observations through a cooling and heating stage microscope yield information on the salinity and deposition temperature chemical analysis by crushing and leaching allows determination using chemical geothermometers of the fluid s chemical composition and initial temperature using thermodynamic modeling we describe the evolution of the solution and the process of fluorite deposition from a rock source in a hot reservoir at a temperature close to 300 degrees c to deposition ending close to 180 degrees c

latitudinal and frequency characteristics of the westward propagation of large scale oceanic variability abstract in the open ocean away from the equator westward propagation is a ubiquitous characteristic of oceanic variability the objectives of the study are to investigate the latitudinal dependence of the frequency of westward propagating variability two dimensional fourier analysis in frequency and zonal wavenumber is applied to time longitude records of sea surface height data obtained from the ocean topography experiment topex poseidon mission the focus of the study is placed on spatial scales larger than the mesoscale the frequency of westward propagation is generally lower than the critical frequency of the first mode baroclinic rossby waves as expected from the conventional theory of rossby waves in a midlatitude ocean however westward propagation with frequency of up to 2 times the critical frequency is also observed at most latitudes this supercritical propagation can be explained by the effects of the vertical shear of the mean flow at midlatitudes and by the effects of the equatorial

a review of the shelf slope circulation along australia s southern shelves cape leeuwin to portland abstract a review is presented of the ocean circulation along australia s southern shelves and slope uniquely the long zonal shelf is subject to an equatorward sverdrup transport that gives rise to the flinders current a small sister to the world s major western boundary currents the flinders current is strongest near the 600 m isobath where the current speeds can reach 20 cm s and the bottom boundary layer is upwelling favourable it is larger in the west but likely intermittent in both space and time due to possibly opposing winds thermohaline circulation and mesoscale eddies the flinders current may be important to deep upwelling within the ubiquitous canyons of the region during winter the leeuwin current and local winds act to drive eastward currents that average up to 20 30 cm s the currents associated with the intense coastal trapped wave field 6 12 day band are of order 25 30 cm s and can peak at 80 90 cm s wintertime winds and cooling also lead to downwelling to depths of 200 m or more and the formation of dense coastal water within the great australian bight and the south australian sea within the great australian bight the thermohaline circulation associated with this dense water is unknown but may enhance the eastward shelf edge south australian current the dense salty water formed within spencer gulf is known to cascade as a gravity current to depths of 200 m off kangaroo island this dense water outflow and meanders in the shelf circulation also fix the locations of a sequence of quasi permanent mesoscale eddies between the eyre peninsula and portland during summer the average coastal winds reverse and surface heating leads to the formation of warm water in the western great australian bight and the south australian sea no significant exchange of shelf water and gulf water appears to occur due to the presence of a dense nutrient rich sub surface pool that is upwelled off kangaroo island the winds lead to weak average coastal currents increasing evidence suggests that el nino events 4 7 year period can have a major impact on the winter and summer circulation these events propagate from the pacific ocean and around the shelf slope wave guide of west australia and into the great australian bight during winter el nino events the average shelf currents may be largely shut down during summer the thermocline may be raised by up to 150 m the nature and role of tides and surface waves is also discussed along with uncertainties in the general circulation and future research

ocean circulation in the great australian bight in an eddy resolving ocean reanalysis the eddy field seasonal and interannual variability abstract the ocean circulation in the great australian bight gab is dominated by the surface intensified leeuwin current lc over the outer continental shelf and the flinders current farther offshore in the gab the lc flows eastwards and varies seasonally with strongest currents of up to 0 8 m s at 130 5 e bringing warm and salty waters as far east as western tasmania the flinders current flows westwards as an undercurrent at depths of around 500 m over the continental slope and at the surface offshore of the lc off the shelf the gab is rich in mesoscale eddies with surface intensified currents of up to 0 4 m s that are coherent over the full water depth getting weaker with depth within deep water eddies isotherms are displaced vertically by up to 200 m eddies in the eastern gab are most energetic in austral winter and spring coincident with the seasonal weakening of the lc the eastern most penetration of gab eddies occurs in austral winter when the lc starts to weaken we hypothesise that the horizontal shear associated with the lc generates eddies in the eastern gab the volume transport of the lc at the head of the gab is typically between 1 and 7 sv with a clear seasonal cycle and the interannual variability of lc transport is up to 2 sv

gold in turkey a missing link in tethyan metallogeny ore geology reviews 28 147 179 reply in his discussion of yigit 2006 kuscu comments mainly on the petrology of the magmatic rocks in turkey with some lesser emphasis on porphyry iocg and skarn deposits although kuscu does not present much supplementary data to improve understanding of the gold metallogeny of turkey i accept the comments in a constructive spirit and welcome this opportunity to reply first of all the original manuscript of yigit 2006 was written in 2003 and submitted for publication in early 2004 therefore many of the references cited in the discussion postdate the original paper furthermore many of the papers cited are abstracts symposia paper proceedings short papers and even websites these unfortunately rarely contain sufficient hard data to support the ideas presented most of the conclusions in these papers are drawn from published literature on the subject rather than prospector regional scale original studies with hard original data kuscu also mentions unpublished turkish geological survey mta reports most if not all of these reports on gold deposits are classified and therefore are not publicly accessible as claimed kuscu highlights the debatable and complicated nature of the tethyan evolution of turkey however yigit 2006 does not make any attempt to solve this contentious issue since the purpose of the paper was rather to present current understanding of gold metallogeny of turkey in the tethyan realm kuscu states that there is no missing link in tethyan metallogeny while studies

ree systematics in hydrothermal fluorite abstract ree patterns of fluorite from 63 post variscan hydrothermal veins of the schwarzwald area germany can be divided into two major groups type a fluorite shows roof shaped paas normalized patterns with enriched mree the turning point of the curvature is at ho or er position all patterns of type a show a distinct positive eu anomaly type b fluorite shows roof shaped patterns with enriched mree and strongly depleted hree and a characteristic steep slope between nd and sm the turning point of the curvature is at gd to dy all patterns of type b show negative or no eu anomalies laser ablation icp ms traverses through single grains combined with cathodoluminescence imagery revealed either i identical ree patterns and total ree concentrations from core to rim ii identical ree patterns but concentration gradients or iii variable ree patterns and concentration gradients from core to rim these features are explained by different degrees of supersaturation or different fluid fluorite ratios during crystallization and by complexly controlled precipitation processes under closed system conditions petrographically late fluorites from several deposits show the characteristics of new fluid batches rather than the expected remobilization features lree enrichment close to the crystal faces in some grains may result from the copreciptiation of a submicrometer sized lree enriched phase or from lree clustering in late cool fluids by comparison with literature data on natural waters from gneissic and granitic aquifers and of leachates of granites and gneisses we show that the hydrothermal vein fluorite preserves the characteristic source related ree feature of the hydrothermal fluid that migrated through either gneissic type a or granitic type b host rocks the immediate host rocks of the veins however are not the source rocks of the ree which indicates large scale fluid convection in the basement gneiss related type a fluorite shows tb ca tb la trends of primary hydrothermal crystallization whereas granite related type b fluorite indicates remobilization of possibly pegmatitic or variscan fluorite

assimilation of surface velocity data into a primitive equation coastal ocean model summer of 1998 are 0 42 and 0 78 respectively demonstrating the effectiveness of the das our estimates of the error covariances are shown to be appropriate through a series of objective statistical tests analysis of the term balances of the model equations show that the dominant modeled dynamical balances are preserved by the das and that uncertainties in the spatial variability of the wind forcing are likely to be one source of model error by varying the relative magnitudes of the estimated forecast and observation error covariances the das is shown to be most effective when approximately 80 of the analysis is made up of the model solution index terms 4263 oceanography general ocean prediction 4219 oceanography general continental shelf processes 4255 oceanography general numerical modeling 3337 meteorology and atmospheric dynamics numerical modeling and data assimilation 4516 oceanography physical eastern boundary currents 4594 oceanography physical instruments and techniques keywords practical data assimilation numerical modeling upwelling highfrequency radar data

the mississippi valley type fluorite ore at jebel stah zaghouan district north eastern tunisia contribution of ree and sr isotope geochemistries to the genetic model abstract the fluorite district of zaghouan north eastern tunisia is characterized by f ba pb zn ore deposits mineralization occurs within stratabound to stratiform bodies either within jurassic back reef limestone uplifted blocks or along unconformity surfaces that separate them from the overlying sequence fluorite mineralization also occurs within fractures crosscutting the uplifted limestone blocks and their overburden despite the similarity of the liassic series throughout the major part of the district stratabound fluorite deposits formed subsequent to a strong epigenetic dolomitization souissi et al 1998 and occurring along the lower middle liassic unconformity are known only at jebel stah and at the adjacent jebel kohol four petrographic types of fluorite are recognized the finely laminated karst deposits fl1a the macrogranular fluorite fl1b resulting from the recrystallization of fl1a and the megacrystalline fluorite fl2 associated to calcite in lodes and fluorite in geodes fl3 this study gives new arguments in terms of the genetic model of the fluorite ore of jebel stah and by using trace metal elements mte rare earth elements ree and sr isotope geochemistry the mte geochemistry shows that the epigenetic dolomites and the fluorite fl1a bear higher concentrations in mn and zn with respect to the fluorites fl1b fl2 and fl3 while the latter are depleted in all mte but enriched in co the similarity of their ree patterns indicates that the latter are coeval and that fl1a fluorite may be considered as the early ore generation the same argument confirms that this geochemical imprint has been inherited from a hydrothermal fluid that had remained in equilibrium with shales at depth fluorite deposition appears related to an oxidized fluid derived from a sedimentary basin fluid circulation may have been triggered in response to hydraulic fracturing within a high geothermal gradient setting especially along the major structural trends fl1b fl2 and fl3 fluorites have been generated from the residual fraction of the ore fluid at later stages of mineralization and in a closed system both mineralization and the epigenetic dolomites are characterized by sr isotope ratios that are higher than the barren lower middle liassic rocks indicating that the sr cannot be derived from the wallrocks however these ratios are higher than the triassic seawater yet consistent with those of the paleozoic period thus the fluorite ore of jebel stah is believed to be remobilized from primary ore deposits which are suspected to be hosted in the late series within this period

water mass analysis and alongshore variation in upwelling intensity in the eastern great australian bight 1 a study of climatological and conductivity temperature depth ctd data for 2004 is made to provide a conceptual model of upwelling for the eastern region of the great australian bight in particular the data and other studies provide strong evidence that shelf break upwelling is confined to the southwest kangaroo island region and does not occur farther to the west off the eyre peninsula rather the upwelled water is likely to remain in a kangaroo island pool until subsequent upwelling events draw the water to the shallower and surface coastal regions of the eastern bight in this manner the surface upwelling apparent off the bonney coast kangaroo island and the eastern great australian bight gab can appear to be simultaneous moreover it appears likely that the water within the kangaroo island pool remains nutrient rich support for this model comes from ctd sections collected in 2004 that show that the upwelled signal cool 26 kg m 3 diminishes in width and intensity with increasing distance from kangaroo island the pattern of fluorescence is similar to that for temperature in the upwelled plume and indicates that the kangaroo island pool remains nutrient rich relatively low oxygen concentrations may indicate a previous bloom the warmest water is found near the shelf break along with very low values of fluorescence and relatively higher levels of oxygen suggesting nutrient limited growth of phytoplankton these data also support the notion that the upwelled nutrient rich water is supplied from the kangaroo island pool and not by shelf break upwelling in the eastern gab anomalously salty and fresh water is identified as resulting from evaporation in coastal bays and groundwater aquifer discharge

estimates of m2 tidal energy dissipation from topex poseidon altimeter data most of the tidal energy dissipation in the ocean occurs in shallow seas as has long been recognized however recent work has suggested that a significant fraction of the dissipation perhaps 1 tw or more occurs in the deep ocean this paper builds further evidence for that conclusion more than 6 years of data from the topex poseidon satellite altimeter are used to map the tidal dissipation rate throughout the world ocean the dissipation rate is estimated as a balance between the rate of working by tidal forces and the energy flux divergence computed using currents derived by least squares fitting of the altimeter data and the shallow water equations such calculations require dynamical assumptions in particular about the nature of dissipation to assess sensitivity of dissipation estimates to input assumptions a large suite of tidal inversions based on a wide range of drag parameterizations and employing both real and synthetic altimeter data are compared these experiments and monte carlo error fields from a generalized inverse model are used to establish error uncertainties for the dissipation estimates owing to the tight constraints on tidal elevation fields provided by the altimeter area integrals of the energy balance are remarkably insensitive to required dynamical assumptions tidal energy dissipation is estimated for all major shallow seas excluding individual polar seas and compared with previous model and data based estimates dissipation in the open ocean is significantly enhanced around major bathymetric features in a manner consistent with simple theories for the generation of baroclinic tides

decay and expansion of the early aftershock activity following the 2011 mw9 0 tohoku earthquake the 2011 m w9 0 tohoku earthquake was followed by an abundant amount of seismicity providing a unique opportunity to analyze the triggering mechanism of great earthquakes although the tohoku earthquake occurred close to a dense seismic network many aftershocks that occurred in the first few hours after the mainshock are not recorded in the earthquake catalogs here we use a template waveform approach to recover as many as possible missing events in the first 12 hours following the tohoku mainshock our analysis is able to detect about 1 4 times more events than those listed in the high sensitivity seismograph hi net earthquake catalog combining our new dataset with earthquakes that occurred at latter times we are able to observe a continuous decay of the aftershock rate and along strike expansion of aftershock area we relate the latter observation to the occurrence of post seismic slip over the deep interface

the geothermal gradient map of central tunisia comparison with structural gravimetric and petroleum data abstract five hundred and fifty temperature values initially measured as either bottom hole temperatures bht or drill stem tests dst from 98 selected petroleum exploration wells form the basis of a geothermal gradient map of central tunisia a global statistical method was employed to correct the bht measurements using the dst as references the geothermal gradient ranges from 23 to 49 c km comparison of the geothermal gradient with structural gravimetric and petroleum data indicates that 1 1 the general trend of the geothermal gradient curves reflects the main structural directions of the region 2 2 zones of low and high geothermal gradient are correlated with zones of negative and positive bouguer anomalies and 3 3 the five most important oil fields of central tunisia are located near the geothermal gradient curve of 40 c km such associations could have practical importance in petroleum exploration but their significance must first be established through further investigation and additional data

fluid inclusion and carbon oxygen and strontium isotope study of the polaris mississippi valley type zn pb deposit canadian arctic archipelago implications for ore genesis the polaris deposit is one of the largest mississippi valley type deposits in the world with 22 million tonnes of ore at 14 zn and 4 pb contained in a single compact orebody surrounded by dolomitized host rocks using detailed sampling of carbonates in the orebody and the dolostone halo this paper aims to characterize the temporal and spatial evolution of the mineralizing system and to understand the mechanisms that controlled the accumulation of this large compact zn pb deposit five types of dolomite have been distinguished including three replacement rd and two pore filling dolomites pd the paragenetic order is rd1 rd2 rd3 pd1 and pd2 pore filling calcite pc postdates all other minerals in most cases sulfides and dolomite did not co precipitate but sphalerite and galena largely overlap with rd3 and pd1 various dolomites are dissolved or replaced by sulfide precipitating fluids sulfides in turn can be overgrown by dolomites colloform texture in sphalerite is widespread fluid inclusions were studied in rd3 pd1 pd2 sphalerite and pc the overall ranges of homogenization temperatures t h and last ice melting temperatures t m ice for fluid inclusions in dolomites and sphalerite are from 67 to 141 c and from 46 7 to 27 0 c respectively consistent with warm basinal brines with high salinities and ca na ratios gas chromatographic analysis of these fluid inclusions indicates low concentrations of hydrocarbons 0 06 mol c o and sr isotopes were analyzed for all dolomites and pc as well as for the fine grained host limestone and early diagenetic calcite sc rc the isotopic values of rd2 rd3 pd1 and pd2 cluster tightly and form largely overlapping domains with respect to the host limestone they are depleted in 18o similar in 13c and slightly enriched in 87sr there are no regular spatial variations for fluid inclusion and isotope data indicating an overall geochemical homogeneity in the hydrothermal system however certain samples close to the fracture zones in the orebody with slightly elevated t h and 87sr 86sr values and depleted 18o values suggest that the fracture zone was the conduit for the hot brines based on the geological and geochemical characteristics of the deposit we propose that sulfide precipitation at polaris was caused by mixing of a reduced metal rich sulfur poor fluid with a reduced metal poor sulfur rich fluid at the site of mineralization the metal carrying fluid ascended along fractures from below the deposit and was hotter than the host rocks whereas the reduced sulfur carrying fluid was delivered to the site of mineralization laterally and was in thermal equilibrium with the host rocks this model can readily explain the dissolution of dolomite during sulfide precipitation and the abundance of colloform sphalerite as well as the low concentrations of hydrocarbons in fluid inclusions

on the leeuwin current system and its linkage to zonal flows in the south indian ocean as inferred from a gridded hydrography abstractthe leeuwin current system lcs along the coast of western australia consists of the poleward flowing leeuwin current lc the equatorward flowing leeuwin undercurrent luc and neighboring flows in the south indian ocean sio using geostrophic currents obtained from a highly resolved hydrographic climatology csiro atlas of regional seas cars this study describes the spatial structure and annual variability of the lc luc and sio zonal currents estimates their transports and identifies linkages among them in cars the lc is supplied partly by water from the tropics an annual mean of 0 3 sv 1 sv 106 m3 s 1 but mostly by shallow 200 m eastward flows in the sio 4 7 sv and it loses water by downwelling across the bottom of this layer 3 4 sv the downwelling is so strong that despite the large sio inflow the horizontal transport of the lc does not much increase to the south from 0 3 sv at 22 s to 1 5 sv at 34 s this lc transport is significantly smaller than previous

evolution movement and decay of warm core leeuwin current eddies abstract characteristics of eddies originating in the leeuwin current lc have been investigated using 10 day sea level anomaly maps of combined topex poseidon and ers altimeter data for the period 1995 2000 during these 6 years 37 long lived anticyclonic eddies were tracked from the west coast of australian to 90 e between three and nine eddies were spawned each year and their trajectories are described in detail most long lived eddies are generated in may june when the lc is most intense and at three preferred locations 20 21 5 s 24 25 s and 28 31 s the temporal evolution and latitudinal variations of the sea level anomalies and their radius and drift speed are discussed topography plays an important role in the evolution and structure of the eddies interactions with topography can induce splitting or merging of eddies which further affects the eddy decay

gold in turkey a missing link in tethyan metallogeny abstract the gold metallogeny of turkey constitutes a sector of the tethyan eurasian metallogenic belt temb within the alpine himalayan orogenic system that formed from jurassic cretaceous to the present this orogenic system produced many different types of deposits related to subduction collision post collision and rifting processes gold deposits as well as other mineral deposits of turkey are mainly concentrated in late mesozoic and tertiary rocks evaluation of the gold metallogeny of turkey is based on a gis database compilation of known gold deposits and prospects currently available data show that turkey has a gold endowment including reserves and resources of approximately 31 5 m oz 979 tonnes in 51 deposits 21 of which contain more than 0 2 m oz gold the other 30 deposits contain a total of approximately 1 m oz 31 tonnes gold resources two recent discoveries kisladag and copler currently contain total resources of 17 6 m oz au 549 tonnes more than 50 of the total turkish gold endowment turkey possesses a wide spectrum of gold deposits related to mesozoic and cenozoic volcanoplutonic arcs however porphyry gold copper epithermal gold including both high and low sulfidation styles and gold rich volcanic associated massive sulfide including both kuroko and cyprus types are the most economically important to date orogenic gold including listwanite hosted placer gold and skarn hosted gold are relatively less important or abundant deposit types other potential gold systems for exploration include carlin type gold detachment fault related gold iron oxide copper gold and gold in carbonate replacement and manganese deposits

a prospective sector in the tethyan metallogenic belt geology and geochronology of mineral deposits in the biga peninsula nw turkey abstract the tethyan metallogenic belt tmb extending from europe through anatolia to iran is one of the world s major metal producing belts and consists of many sectors mineral deposits of the biga peninsula in northwestern turkey exhibit in many ways the characteristics of mineral deposits found throughout the belt biga peninsula tectonically forms the westernmost part of the sakarya zone and easternmost part of the rhodope zone at the intersection of gondwana and laurasia the biga peninsula metallogeny research and exploration project created a gis inventory of mineral deposits and prospects and classified them genetically to evaluate the mineral deposit potential using genetic models based on descriptive data the gis database consisting of 128 deposits or prospects helped to generate new prospects and potential prospects this field based study indicated that the biga peninsula forms a prime target for gold copper exploration not only in turkey but in the world the current economically significant mineral deposits of the biga peninsula were shaped by cenozoic calc alkaline magmatism ranging between 52 and 18 ma and related to mainly collisional and post collisional tectonic regime epithermal au ag deposits including high hs low ls and intermediate sulfidation is styles porphyry au cu mo and base metal skarn systems are economically the most important though there are no currently economic examples of some of them in the biga peninsula other deposit types include carlin like distal disseminated au ag orogenic au especially listwanite hosted volcanogenic mn and u lateritic ferricrete fe deposits carbonate replacement cr and placers several active metal mines such as balya arapucandere and koru are operating in the biga peninsula kucukdere au ag deposit in balikesir is the only gold mine in the biga peninsula except for by product gold produced from base metal deposits results of the study show current total gold endowment of the biga peninsula including reserves and or resources is 9 18 moz gold 284 2 t contained in twelve different deposits of these only 6 contain significant gold 0 3 moz or 10 t halilaga porphyry and agi dagi and kirazli hs epithermal systems have an ongoing resource estimate and halilaga is a candidate to be one of the largest cu au deposits not only in the biga peninsula but in turkey currently newly discovered tepeoba is the largest porphyry cu mo au deposit with known resources in the biga peninsula here the first 40 ar 39 ar step heating age data conducted on some of the major hs epithermal gold deposits and causative intrusives in the biga peninsula are reported geochronological results from this project evaluated with previous studies indicate at least 3 phases of porphyry and 2 phases of high sulfidation epithermal gold mineralization in the biga peninsula the most important mineralizing phases and related host rocks for gold mineralization range from 38 to 22 ma the oligocene is especially important for economic epithermal and porphyry systems in the biga peninsula which is comparable to deposits in the oligo miocene serbomacedonian rhodope metallogenic belt of the balkan peninsula in se europe

the solubility of fluorite in h2o and h2o nacl at high pressure and temperature abstract the solubility of fluorite in h2o and h2o nacl has been measured at 600 1000 c 0 5 2 0 gpa in a piston cylinder apparatus fluorite dissolves congruently at all conditions investigated the data indicate that the concentration of fluorite dissolved in h2o is low at 600 c and 0 5 gpa 0 0014 mol kg h2o but increases strongly with temperature t and pressure p to 0 247 mol kg h2o at 1000 c 2 gpa the data were fit with the equation log mcaf2 6 587 2 774p1 2 2 266 10 3 4 699 10 4p t where mcaf2 is molality of caf2 t is in kelvin and p is in gpa fluorite solubility was also measured in h2o nacl fluids at 800 c and 1 0 gpa results indicate a strong increase in dissolved fluorite concentration with increasing nacl content from 0 028 mol kg h2o at xnacl 0 to 1 673 mol kg h2o at xnacl 0 486 where xnacl is the mole fraction of nacl in the fluid the data were fit to mcaf2 0 01035 1 141xnacl 4 694xnacl2 the results indicate that f mobility will be further enhanced by saline brines in high p t igneous and metamorphic environments high f solubility in h2o and h2o nacl in the deep crust and upper mantle can promote mobilization of high field strength elements rare earth elements u and th through transport as f bearing complexes

observational evidence for a southern hemisphere oceanic supergyre 1 a high resolution hydrographic atlas resolves the narrow boundary flow of the western pacific gyre and its pathway around tasmania southern australia and into the indian ocean basin this confirms recent model descriptions of a southern hemisphere supergyre a nested system of subtropical gyres the observations show that the gyre flow is squeezed into a narrow band between tasmania and the antarctic circumpolar current the residue of east australian current transport turns westward around tasmania and leaks into the indian ocean while there is also a limited form of gyre connection between the indian and atlantic systems south of africa with a mean outflow of agulhas current water into the atlantic basin these gyre circulations remain far more discrete the gyre coupling and the east australian current in particular provide the mechanism by which sub antarctic mode water and antarctic intermediate water are distributed between the ocean basins

global observations of large oceanic eddies 1 ten years of sea surface height ssh fields constructed from the merged topex poseidon t p and ers 1 2 altimeter datasets are analyzed to investigate mesoscale variability in the global ocean the higher resolution of the merged dataset reveals that more than 50 of the variability over much of the world ocean is accounted for by eddies with amplitudes of 5 25 cm and diameters of 100 200 km these eddies propagate nearly due west at approximately the phase speed of nondispersive baroclinic rossby waves with preferences for slight poleward and equatorward deflection of cyclonic and anticyclonic eddies respectively the vast majority of the eddies are found to be nonlinear

europium redox equilibria in aqueous solution thermochemical data and recent advances in theoretical aqueous solution chemistry enable prediction of the relative stabilities of aqueous eu2 and eu3 over a wide range of temperatures and pressures at low temperatures near earth surface conditions the aqueous geochemistry of europium should be dominated by the trivalent state except possibly in the most reducing alkaline pore waters of anoxic marine sediments however at temperatures greater than about 250 c and elevated pressures divalent europium should predominate even with significant amounts of complexing trivalent europium is not stable at elevated temperatures and pressures consequently under most hydrothermal and metamorphic conditions europium in aqueous solution should be divalent at intermediate temperatures around 100 c significant activities of both eu2 and eu3 and related complexes can occur in aqueous solutions depending on the oxidation state and the ph of the solutions and the activities of potential ligands such as sulfate carbonate and chloride the predicted stability of divalent europium in aqueous solution at elevated temperatures is consistent with the large positive europium anomalies in rare earth element patterns of high temperature barites of hydrothermal and metamorphic origin reported by guichard et al 5 and with the observed depletion of europium as a result of high temperature sericitization of feldspar bearing assemblages discovered by alderton et al 1 it is suggested that significant fractionation of europium relative to the other rare earth elements may take place during high temperature hydrothermal alteration processes such as in the mid oceanic ridge systems because of the expected stability of divalent europium during these processes

evidence for cross formational hot brine flow from integrated 87sr 86sr ree and fluid inclusions of the ordovician veins in central tarim china abstract rare earth elements 34s 87sr 86sr and 18o were determined and fluid inclusions were analyzed of fracture filling barite anhydrite fluorite calcite and quartz from upper ordovician carbonates in central tarim china the aim was to assess the origin evolution and flow of fluid in the fractures there was mixing of relatively hot ba rich and 87sr rich fluid with in situ basinal water and fresh water which was relatively cool and more radiogenic the hotter fluid is hydrothermal as indicated by homogenization temperatures hts about 20 c higher than the formation and was most likely derived from precambrian to lower cambrian clastic rocks or and from the basement through faults this is because almost all of 87sr 86sr ratios of late stage fracture fillings mainly 0 70889 0 71036 and present brines are higher than that of upper ordovician limestones the hydrothermal fluid was enriched in f eu2 ba2 sr2 and zn2 during migration as indicated by the positive relationships of eu to sr ba and zn when the hydrothermal fluid mixed with local basinal water it precipitated isotopically normal s anhydrite fluorite and calcite with positive eu anomalies the precipitation of these ca minerals was followed by thermochemical so4 reduction tsr of dissolved sulphates by hydrocarbons it was likely that only part of the so 4 2 was reduced and the generated h2s leaked out thus barite deposited from residual so 4 2 has abnormally high 34s values from 42 to 47 and the generated h2s is isotopically light from 15 to 18 subsequently hydrothermal fluid was likely to have mixed with relatively cool and more 87sr rich freshwater resulting in precipitation of quartz and fluorite with salinities as low as 0 5 wt nacl equiv and 87sr 86sr ratios up to 0 71036

genesis of the st lawrence fluorspar deposits as indicated by fluid inclusion rare earth element and isotopic data more than 40 separate fluorspar veins are associated with the lower carboniferous st lawrence granite of southeastern newfoundland with more than 3 4 million short tons mined since 1933 and a further 9 million short tons of reserves contained in the three main veins it is estimated from these tonnages that fluorine concentrations in the magma of only 19 ppm would have been adequate to form the veins much less than the average of 1 567 ppm f found in the granite fluid inclusions show that salinities remain within the range of 5 to 15 equivalent weight percent nacl although homogenization temperatures fluctuate between 100 degrees and 500 degrees c evidence for boiling between 450 degrees and 223 degrees c indicates that the homogenization temperatures are trapping temperatures at low pressures between 65 and 650 bars some 18 o depletion in the aqueous fluids owing to unmixing and loss of co 2 in the fluorite veins delta 18 o quartz is approximately 14 per mil and calculated fluid delta values are 10 per mil 450 degrees c to 6 per mil 120 degrees c waters released from low temperature magmatic fluids which underwent transient mixing with a cool low 18 o meteoric reservoir modified journal abstract

pattern and velocity of propagation of the global ocean eddy variability 1 satellite altimeter data are used to study the characteristics of the horizontal propagation of eddy variability of the global oceans decade long time series of sea surface height is analyzed for finding the maximum cross correlation with neighboring time series within a window of space and time lags the space and time lags corresponding to the maximum correlation allow an estimate of the propagation velocity of the eddy variability that dominates the variance of sea surface height anomalies the method cannot distinguish the various forms of eddy variability isolated eddies and fronts the meandering of ocean currents or planetary waves however the results provide at a given location of the global oceans a uniquely determined propagation velocity that represents a time averaged description of the tendency of the movement of the local eddy variability the propagation velocity is highly inhomogeneous in space outside the equatorial zone the zonal propagation is intrinsically westward modified by ocean currents which could reverse the zonal propagation to eastward in regions like the gulf stream and the antarctic circumpolar current at midlatitudes and high latitudes the propagation pattern is highly affected by the path of ocean currents and the shape of bottom topography at tropical latitudes the meridional propagation is convergent toward the equator in the western basins and divergent away from the equator in the eastern basins comparison with the simulations of an eddy permitting ocean general circulation model shows overall agreement especially in the latitudinal variation of the zonal propagation velocity the result suggests that the model has captured the essence of the dynamics governing the propagation of ocean eddy variability

modeling studies of the leeuwin current off western and southern australia the leeuwin current strengthens considerably from february to may each year following the slackening of southerly coastal winds strong eddies develop a high resolution multilevel primitive equation ocean model is used to examine this eddy development in an idealized way by considering the development of flow from rest when temperatures are initially given the observed longshore gradients the system is allowed to geostrophically adjust in the absence of longshore winds and of any surface heat flux two types of experiments are conducted the first type uses the indian ocean climatological temperature gradient forcing case 1 and 2 while the second type repeats the first experiment with the added contribution of the north west shelf nws temperature profile cases 3 and 4 to investigate the additional effects of coastline irregularities cases 1 and 3 use an ideal coastline while cases 2 and 4 use an irregular realistic coastline in all cases maximum surface velocities occur at cape leeuwin where the leeuwin current changes direction and off southern australia maximum undercurrent velocities occur off western australia in case 1 cape leeuwin and the western australian coast are the preferred locations for the development of warm anticyclonic eddies which are generated due to a mixed instability mechanism in case 2 the warm anticyclonic eddies occur in the vicinity of coastal promontories and at cape leeuwin while advection of warm water is present along the entire coast in case 1 the irregular coastline geometry limits the extent of warm water in case 2 the added contribution from the nws water in cases 3 and 4 augments the onshore geostrophic inflow to produce a model leeuwin current and undercurrent that are more vigorous and unstable than in the previous cases in case 3 the nws water adds strong horizontal shear to the coastal equatorial region of the domain and vertical shear to the inshore current it also advects warmer water along the entire coast in case 4 the addition of both the nws water and the irregular coastline results in the establishment of a stronger surface current and undercurrent than in the previous cases however the irregular coastline limits the extent of the advection of the nws warmer water along the australian coast in all cases warm anticyclonic eddies develop at the coast cold cyclonic eddies form from the limbs of the established warm anticyclonic eddies with the result that two counterrotating cells are developed once the eddy pairs begin their westward propagation the leeuwin current intensifies as nonlinear effects result in a jet between the eddies and the coast these effects translate downstream to augment the current velocities at the coast which due to a mixed instability mechanism result in the development of new anticyclonic eddies at the coast the results from case 4 which has the most realistic features highlights the major characteristics of the leeuwin current and agrees well with available observations these results show that the model successfully captures the qualitative nature of the nonlinear eddying response of the leeuwin current

the influence of mixing on primary productivity a unique application of classical critical depth theory mixing and primary productivity was examined in upwelling influenced nearshore waters off south western eyre peninsula swep in the eastern great australian bight egab the economically and ecologically important shelf region off southern australia that forms part of the southern and indian oceans mixing stratification in the region was highly temporally variable with a unique upwelling circulation in summer autumn november april and downwelling through winter spring may september highest productivity was associated with upwelled stratified water up to 2958 mg c m

evidence of a large seasonal coastal upwelling system along the southern shelf of australia 1 we report observational existence of a large seasonal coastal upwelling system that establishes in austral summer december april along australian southern shelves wind driven upwelling events occur simultaneously in three upwelling centres spanning a distance of 800 km during each summer period there are 2 3 major upwelling events each lasting 1 week the simultaneous rapid response of sst to wind forcing in the upwelling centres which display vastly different shelf widths points to the existence of a larger scale process that carries cold water onto the shelf prior to the upwelling season exploration of a major upwelling event in march 1998 shows the evolution of peak surface chlorophyll a concentrations of 4 g l lagging the onset of upwelling by 1 week the associated exponential growth rate can be estimated at 0 4 d 1 another week later we found a distinct sub surface chlorophyll a maximum at a depth of 50 m centred along the upwelling front reasons for the formation of this maximum are not fully understood

tasman leakage in a fine resolution ocean model tasman leakage the westward flow of thermocline waters south of australia from the pacific to the indian ocean is one of the lesser studied of the inter ocean exchanges here some of the properties of the tasman leakage are inferred from lagrangian particles integrated using the three dimensional velocity fields of the 1 10 degree resolution ofes model the mean tasman leakage in this model is 4 2 sv with a standard deviation of 4 3 sv the heat flux associated with this leakage lies in the range 0 08 0 18 pw there is large variability in the tasman leakage on both sub weekly and inter annual scales but no trend over the 1983 1997 period despite the large weekly variability with peaks of more than 20 sv it appears that less than half of the tasman leakage is carried within eddies

oxidation state of europium in scheelite tracking fluid rock interaction in gold deposits abstract we used xanes spectroscopy to measure the oxidation state of europium in situ at near m resolution in hydrothermal scheelite from the giant archean gold deposits of kalgoorlie western australia by combining these measurements with xrf imaging it is possible to distinguish inhomogeneities in eu2 eu3 ratios that developed during mineral precipitation from the effects of subsequent hydrothermal alteration and weathering thermodynamic analysis reveals that under the conditions typical of the formation of many au deposits the eu2 eu3 ratio in the hydrothermal fluid is highly sensitive to ph the range in ph calculated from the eu2 eu3 ratios in the analyzed scheelite corresponds to a maximum in au solubility under the ore forming conditions and suggests buffering of ph by the co2 aq rich fluid the primary heterogeneity of the karlgoorlie scheelite most likely results from ph oscillating between fluid and rock buffered conditions and reflects the dynamics of the hydrothermal system

aspects of the mean wintertime circulation along australia s southern shelves numerical studies abstract a high resolution numerical model is used to study the mean wintertime shelf slope circulation between the gulfs of south australia and the west coast of tasmania the mean downwelling favorable winds for the region result in a continuous eastward coastal current cc extending from cape leeuwin to the eastern coast of tasmania the magnitude of the cc is generally largest over the shelf break has speeds of more than 40 cm s 1 transport 2 4 sv sv 106 m3 s 1 and is generally in good agreement with observations the relative importance of the leeuwin current zonal winds and density gradients to the shelf circulation is established within bass strait the eastward circulation is in good agreement with observations and simple models show that about 30 of the transport arises from local winds and the remainder from the cc the total transport through the strait 0 95 sv is shown to be controlled by sea level on the east coast of tasmania a current of up to 10 cm s 1 is also found to flow

eddy formation through the interaction between the leeuwin current leeuwin undercurrent and topography abstract the surface and subsurface circulation off south west australia was simulated using the regional ocean modelling system roms a primitive equation ocean model with terrain following s coordinates the major currents in this region the leeuwin current and leeuwin undercurrent were reproduced by specifying only temperature and salinity distributions from climatology the application of wind stress subsequent to the model reaching a quasi steady state resulted in the generation of the seasonal capes current a northward flowing current on the continental shelf associated with coastal upwelling the simulated currents compared well with the observed current patterns including the location and maximum current speeds shelf topography variations and bottom shear which generated vorticity influenced eddy formation eddies separated from the leeuwin current and the leeuwin undercurrent migrated westward and exited the model domain through merging dissipating or through an open boundary in the model simulations the undercurrent produced mostly cyclonic eddies due to strong negative vorticity where the current flowed against the continental slope the leeuwin current produced anticyclonic warm core eddies initiated from the formation of meanders which were strongest at the surface the eddy field was dominated by anticyclonic eddies at the surface and cyclonic eddies at 500 m the interaction between the leeuwin current and leeuwin undercurrent led to the formation of eddy pairs