refraction and shoaling of nonlinear internal waves at the malin shelf break abstract this paper applies a numerical model to explain the refraction and shoaling of nonlinear internal waves observed at the malin slope for a sequence of tidal cycles in the summer of 1995 the model is first order in dispersion and second order in nonlinearity and is based on the extended korteweg de vries ekdv equation the ekdv model is applied along a set of rays and includes the effect of variable depth the model predicts that an initial long wavelength wave which lies in water of depths between 500 and 900 m develops into a set of internal solitary waves as it passes across the shelf break and onto the continental shelf in agreement with observations the extent of refraction is small because the internal waves are high frequency and in this case the refraction is not strongly dependent on the nonlinear adjustment to phase speed in the observations the internal wave amplitude measured in terms of near surface currents or thermocline displacement initially grows as the wave crosses th

spatial and temporal isotopic domains of contrasting igneous suites in western and northern sulawesi indonesia abstract palaeocene to pliocene magmatism in nw sulawesi shows a progression from an older series with calc alkaline tholeiitic signatures 51 17 ma to a younger series of mafic intermediate high k magmas 14 5 ma and felsic k rich calc alkaline cak magmas 9 2 ma the isotopic and geochemical compositions of the older series samples indicate that the more westerly samples have been generated in a continental arc setting and the more easterly samples in an oceanic arc this distinction defines the boundary between the western and northern sulawesi tectonic terranes the younger series high k magmas have unusual isotopic compositions with variable but low 143nd 144nd high 87sr 86sr values and high 208pb 204pb for their 206pb 204pb ratios compared to subduction related magmas the diversity of the isotopic compositions points towards a source with a long and heterogeneous geochemical evolution most likely located within the australian subcontinental lithospheric mantle the younger series felsic cak magmatism has a more homogeneous isotopic and geochemical signature and reflects melting of continental crust of australian origin this geochemical progression in time is very similar to that seen in central sulawesi chem geol 156 1999a 67 and is best explained by normal subduction of an oceanic plate followed by melting of an underthrust sliver of australian continent the size of this microcontinent can be estimated from the areal extent of low nd isotope magmas in western sulawesi ranging from approximately 4 s to 1 n underthrusting must have happened prior to 14 ma indicating that this event cannot be equated to the collision between sulawesi and the sula platform which occurred at 5 ma while subduction beneath western sulawesi ceased prior to the onset of potassic magmatism in this region it continued beneath northern sulawesi producing predominantly calc alkaline suites

geology and molybdenite re os age of the dahutang granite related veinlets disseminated tungsten ore field in the jiangxin province china this is a brief research report about the recently discovered and currently being explored dahutang tungsten deposit or ore field in northwestern jiangxi south central china the deposit is located south of the middle lower yangtze river valley cu au mo fe porphyry skarn belt yrb the mineralization is genetically associated with cretaceous porphyritic biotite granite and fine grained biotite granite and is mainly hosted within a neoproterozoic biotite granodiorite batholith the dahutang ore field comprises veinlets disseminated 95 of the total reserve breccia 4 and wolframite scheelite quartz vein 1 ore styles the mineralization and alteration are close to the pegmatite shell between the cretaceous porphyritic biotite granite and neoproterozoic biotite granodiorite and the three styles of ore bodies mentioned above are related to zoned hydrothermal alteration that includes greisenization k feldspar alteration silicification carbonatization chloritization and fluoritization arranged in time early to late and space bottom to top five samples of molybdenite from the three types of ores have been collected for re os dating the results show re os model ages ranging from 138 4 ma to 143 8 ma with an isochron age of 139 18 0 97 ma mswd 2 9 the quite low re content in molybdenite falls between 0 5 ppm and 7 8 ppm that is indicative of the upper crustal source this is quite different from molybdenites in the yrb cu au mo fe porphyry skarn deposits that contain between 53 ppm and 1169 ppm re indicating a mantle source the dahutang tungsten system is sub parallel with the yrb porphyry skarn cu au mo fe system both are situated in the north margin of the yangtze craton and have a close spatial temporal relationship this possibly indicates a comparable tectonic setting but different metal sources both systems are related to subduction of the paleo pacific plate beneath the eurasian continent in early cretaceous the cu au mo fe porphyry skarn ores are believed genetically related to granitoids derived from the subducting slab whereas the porphyry w deposits are associated with s type granitoids produced by remelting of the upper crust by heat from upwelling asthenoshere

sm nd and sr isotope systematics of scheelite from the giant au w deposit muruntau uzbekistan implications for the age and sources of au mineralization the application of the sm nd isotope system of scheelite to dating of low sulfide quartz vein hosted au mineralization is still under discussion in the present work new sm nd and rb sr data for scheelite from the giant muruntau myutenbai au deposit kyzylkum western uzbekistan are discussed based on the geological relationship mineralogical properties and trace element characteristics two types of scheelite can be distinguished within the deposit the first one is represented by early bluish luminescent and weakly coloured scheelite generation 1 found within strongly deformed flat quartz veins the apparent isochron defined by this scheelite 351 22 ma is interpreted as a mixing line typically brownish to orange and yellowish luminescent scheelite from steeply dipping veins generation 2 defines a sm nd isochron age of 279 18 ma end 9 5 0 3 mswd 1 5 no evidence for mixing or disturbance by late alteration were found for these scheelites this sm nd isochron age agrees with the rb sr and k ar age range for wall rock alteration in this deposit reported previously the age of 280 ma is interpreted to date the high grade ore formation in the muruntau deposit there are currently no reliable age data available on the magmatic events in the muruntau region probably there is some overlap in time of the hercynian gold deposition with the intrusion of lamprophyric dykes the nd and sr isotopic signatures of scheelite define the wall rocks mainly metasiltstones and metasandstones as the most probable sources for these elements in scheelite

age and genesis of the w bi cu f au nui phao deposit northeast vietnam constrains from u pb and ar ar geochronology fluid inclusions study s o isotope systematic and scheelite geochemistry abstract northeast vietnam comprises several tectonic units which host number of metallic deposits of different types from orogenic gold to intrusion hosted pge deposits the lo gam domain being part of the ne vietnam hosts the lang vai gold district a several pb zn deposits and the recently discovered super large w bi cu f au nui phao deposit the nui phao deposit is 87 9 mt at 0 19 wo3 7 95 caf2 0 18 cu 0 19 g t au and 0 09 bi while the measured resource is 25 1 mt at 0 25 wo3 8 4 caf2 0 23 cu 0 26 g t au and 0 108 bi the nui phao deposit is a very interesting object for research due to location of the orebodies between of two granite massifs of the cretaceous da lien and triassic nui phao age consequently the temporal and genetic relationships of mineralization with a certain magmatic events are unclear here we present mineralogical compositional and geochronological data of the nui phao deposit in conjunction with physical chemical researches to understand the ore genesis and its genetic link to a certain magmatic events according to our observations at least three different mineral associations are distinguished at the nui phao deposit which include greisens skarns and quartz sulfide ore skarn and sulfide ore mineral assemblages generally contain abundant scheelite associated with pyrrhotite chalcopyrite and native bismuth the greisens consist of fluorite muscovite and rare molybdenite the results of fluid inclusions study indicate that at the nui phao deposit the initial ore forming fluid was represented by the reduced co2 ch4 h2o nacl cacl2 system characterized by high temperatures and moderate salinities the fluid boiling is the dominant mechanism for ore deposition at the nui phao deposit relatively homogeneous isotopic compositions of oxygen 18oh2o 6 73 to 9 24 and sulfur 34s 1 6 to 3 5 that closely correspond to magmatic source suggest that the ore forming fluid was generated from cooling granite pluton without contribution meteoric water the systematic studies of scheelite composition show that ree contents decrease from early to late scheelite generations which suggest gradual ree depletion of the ore forming fluid without significant fractionation between lree mree and hree the rees of scheelite are mainly controlled by the substitution mechanisms ca2 w6 ree3 nb5 and 3ca2 2ree3 ca by combining ree features y ho ratios and other characteristics of the nui phao deposit we propose a single magmatic source for hydrothermal ore firming fluids without fluid mixing a significantly contribution of material during fluid rock interaction is also unlikely the combination of mineralogical and geochemical features as well as complex studies of the formation conditions allowed us to conclude that gold at the nui phao deposit occur as impurities in the native bismuth the ages of the da lien and nui phao granite massifs and the nui phao deposit have been estimated to be ca 84 ma ar ar 244 ma u pb and ca 85 ma ar ar respectively indicating a genetic relationship between the mineralization and the cretaceous magmatic event

middle palaeolithic raw material gathering territories and human mobility in the southern massif central france first results from a petro archaeological study on flint during the middle palaeolithic in the south eastern massif central and the bordering rhone valley humans collected almost all their raw materials from various secondary outcrop which can be distinguished by the inherent characteristics of the materials similar lithic facies are unlikely to be encountered on two or more different natural outcrops and every artefact shows a surface that is well enough preserved to be studied according to a morphoscopic analysis at various magnifications for all sites some more remote sources were also exploited however most of the supposed exogenous materials such as some cretaceous flints identified in the velay assemblages of sainte anne i and baume vallee for example come from the heart of the massif where they occur in secondary alluvial deposits nevertheless the extent of the foraging territories as revealed by raw materials sourcing covers a large band of various relief between the western and southern causses the rhone corridor and the northern limagne and forez plains and animal species hunted by these groups express an environmental mosaic which fits with the image of landscape given by the raw materials

the use of sem eds pixe and edxrf for obsidian provenance studies in the near east a case study from neolithic catalhoyuk central anatolia in this paper we evaluate the relative analytical capabilities of sem eds pixe and edxrf for characterizing archaeologically significant anatolian obsidians on the basis of their elemental compositions the study involves 54 geological samples from various sources together with an archaeological case study involving 100 artifacts from neolithic catalhoyuk central anatolia with each technique the artifacts formed two compositional groups that correlated with the east gollu dag and nenezi dag sources the non destructive capabilities of these methods are emphasized albeit with certain analytical limitations in the case of sem eds suggesting important new techniques for near eastern obsidian provenance studies

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

quantitative edxrf studies of obsidian sources in northern hokkaido quantitative trace element data from six obsidian sources on the japanese island of hokkaido is presented previous work by japanese scholars has utilized neutron activation analysis naa focusing on the rare earth elements or qualitative energy dispersive x ray fluorescence edxrf in this study non destructive edxrf is used to generate trace element data for 9 elements bivariate plots of the incompatible trace elements ba rb sr y and zr can be used to separate the obsidian sources in this study source separation was confirmed by using linear discriminant analysis stepwise discriminant analysis indicates that ba sr rb ti y and zr are the most discriminating elements

late pleistocene early holocene maritime interaction in southeastern indonesia timor leste abstract this study analysed over 1000 obsidian stone artefacts excavated from two adjoining shelters at tron bon lei on alor island indonesia using portable xrf the study showed an unambiguous separation of three different source locations groups 1 2 and 3 two sources group 2 and 3a b c dominate the assemblage numerically group 1 and 2 indicate use of a single volcanic formation with a strong match between group 1 artefacts and artefacts from sites in timor leste obsidian occurs in the earliest occupation layer in the alor sites but does not include group 1 artefacts which occur only after approx 12 000 cal bp currently the geographical location of the group 1 outcrop is unknown however based on the late appearance of the group 1 artefacts in the alor sequence it is likely that the location is not on alor but rather on another island of the sunda chain the dating of group 1 artefacts in widely spaced sites on the never geographically connected islands of timor and alor indicates that maritime interaction between islands began by at least the terminal pleistocene the distribution of the obsidian in tron bon lei shelter pit b shows that there were periods of more intense interaction punctuated by periods when interaction declined or ceased

contrasting zircon hf and o isotopes in the two episodes of neoproterozoic granitoids in south china implications for growth and reworking of continental crust abstract the genetic links among rift magmatism crustal growth and water rock interaction are an important issue about mass and heat transfer between mantle and crust during supercontinent breakup a combined study of hf and o isotopes in zircons from neoproterozoic granitoids in south china provides evidence for growth and reworking of juvenile and ancient crusts with different styles of water rock interactions along rift tectonic zones two generations of the granitoids show contrasting features in both zircon hf and o isotope compositions indicating their distinct petrogenesis the 825 ma granitoids exhibit negative ehf t values of 3 4 0 8 to 1 6 0 8 with old model hf ages of 1 81 0 07 to 1 92 0 10 ga and high 18o values of 8 7 to 10 4 these indicate that the source material of granitoid magmas was derived from melting of paleoproterozoic basement that has the hf isotope signature similar to the enriched mantle but experienced chemical weathering process before anatexis reworking of ancient crust is demonstrated to occur at 825 ma in the orogenic collapse zone with overprinting of subsolidus hydrothermal alteration during magma emplacement in contrast the 760 750 ma bimodal intrusives are characterized by positive ehf t values of 3 5 0 8 to 9 9 0 8 with young model hf ages of 0 94 0 06 to 1 18 0 06 ga and both low and high 18o values of 4 2 to 6 2 relative to 5 3 0 3 for the normal mantle zircon prompt reworking of juvenile crust is suggested to occur at 750 ma in the rifted tectonic zone with occurrence of supersolidus hydrothermal alteration and local low 18o magmatism during supercontinent breakup contributions of the depleted mantle to their magma sources are contrasting in the two episodes of magmatism in association with breakup of the supercontinent rodinia while the change in melt source from the crust to the mantle keeps pace with the advance from continental rifting to supercontinent breakup significant transport of both heat and material from the depleted mantle to the continental crust only occurred along the active rifting zone in either case the growth and reworking of continental crust are episodically associated with rift magmatism

direct evolution of w rich brines from crystallizing melt within the mariktikan granite pluton west transbaikalia uneconomic tungsten mineralization associated with the mariktikan granite pluton of the transbaikalian igneous province eastern siberia is confined to a marginal part of the pluton referred to as the andreyevsky body this is composed of rocks similar to those of the main pluton but is likely to be an autonomous although kindred body on the basis of cross cutting relationships between rock varieties and their textural features the crystallization history is subdivided into three stages of unequal duration melt and fluid inclusions related to each of them have been studied using microthermometric and micro analytical procedures including a technique for atomic emission spectroscopy of individual fluid inclusions opened by a laser microprobe during the main crystallization stage 1045 1012 c more than 70 of the parental magma is believed to have crystallized at the level studied resulting in the formation of a crystalline framework rigid enough for the appearance of fractures within which some portion of the intercrystalline melt accumulated giving rise to thin aplite veins almost complete crystallization of intercrystalline and fracture hosted melt occurred during the late stage 1012 990 c whereas during the final stage only small bunches of schlieric sometimes miarolitic pegmatite were formed from a few pockets of residual melt 990 917 c in spite of the low water content of the melt about 1 wt fluid separation took place from the onset of crystallization during the main crystallization stage the exsolved fluid divided into two immiscible phases co2 rich gas and salt rich liquid brine however it was homogeneous thereafter major ore components of the brine mn fe w displayed different behaviour as crystallization progressed w concentration was below 0 1 wt at the main stage attained 1 wt during the late stage and increased to 1 8 wt at the final stage comparison of these data with calculations carried out using estimated parameters for the parental magma enables us to infer that obtained concentration values are reasonable for the special case studied here however they are unlikely to be attainable if the magma is h2o enriched and lacks an anomalously high w content in the andreyevsky body of the mariktikan pluton the following features of the parental magma made possible the generation of w rich solutions 1 high liquidus temperature 1045 c and elevated cl content c 0 15 wt that resulted in enlargement of the fluid melt distribution coefficient c 10 2 low water content c 1 and elevated w content c 0 001 wt that provided a relatively high w h2o ratio within the system at the same time because of the low water content of the magma the total mass of w bearing solutions has proved to be insufficient for the production of large scale mineralization a reduced w content of the great bulk of the exsolved brine may have had an unfavourable effect as well

forensic ar ar dating a provenance study of middle stone age obsidian artifacts from ethiopia abstract obsidian sourcing based on geochemistry is widely applied to reconstruct commerce patterns and dissemination of early hominid groups due to problems concerning potential intra source variability or homogeneity of a geological source over large areas parameters additional to this classical approach are desirable here we present the first 40 ar 39 ar investigation of middle stone age msa obsidian artifacts i e debitage pieces for this purpose as well as of potential geological obsidian sources from ethiopia with the present pilot study we demonstrate that 40 ar 39 ar geochronology represents a reliable and powerful tool for archaeological provenance studies complementary to the geochemical approach and more recently applied techniques like fission track counting or mossbauer spectroscopy two independent sets of debitage and potential source rock samples were dated by the 40 ar 39 ar method debitage pieces from the kulkuletti excavation site and obsidian samples from the nearby obsidian outcrop worja central ethiopia exhibit basically identical age ranges as well as similar ca k and cl k ratios supporting the debitage source rock relationship previously inferred on geochemical grounds a second small set of geochemically characterized debitage samples from the porc epic cave and potential source rocks from an obsidian outcrop at kone eastern ethiopia however have different 40 ar 39 ar ages and ca k and cl k ratios these results contradict the previous conclusion about a debitage source rock relationship of the porc epic and kone samples made on the basis of geochemistry a negash m s shackley archaeometry 48 2006 1 additional sampling at the kone outcrop as well as of other obsidian occurrences in the greater area is needed to unambiguously pinpoint the origin of these obsidian tools

origins of nd sr pb isotopic variations in single scheelite grains from archaean gold deposits western australia accessory gangue scheelite cawo4 from the archaean mt charlotte lode au deposit can be divided into two types with different rare earth element ree signatures in some scheelite grains specific ree signatures are reflected by different cathodoluminescence colours which can be used to map their often complex oscillatory intergrowths domains with specific ree contents from two grains were sampled for sm nd rb sr and pb isotopic analyses using a micro drilling technique type i scheelite is strongly enriched in middle ree mree and eu anomalies are either absent or slightly positive four fragments collected from type i regions of two crystals have initial 87sr 86sr and end values ranging from 0 70141 to 0 70163 and 2 5 to 3 5 respectively and pb isotope ratios reflecting the composition of greenstone sequence this may indicate that nd and pb have their source either locally or regionally in the greenstones basic greenstone lithologies have 87sr 86sr 0 7015 and the radiogenic sr signatures indicate that part of the sr originated from felsic lithologies located either within or beneath the host greenstone pile alternatively the sr signature may have evolved from preferential leaching of a rb rich mineral during hydrothermal alteration of the greenstone the ree patterns of type ii scheelite are either flat or mree depleted and have strong positive eu anomalies three fragments collected from type ii regions of the same two crystals have initial 87sr 86sr ratios and end values between 0 70130 and 0 70146 and 1 1 to 2 6 respectively and pb isotope signatures that are once again similar to that of the greenstone this implies that 87sr 86sr ratios in type ii fluids were closer to those of the host dolerite 0 7008 0 7013 due to more extensive fluid interaction with the dolerite a positive correlation between na and ree suggests that ree3 are accommodated by the coupled substitution ree3 na 2 ca2 into both type i and type ii scheelite this is consistent with a fractional crystallisation model to explain the change in ree patterns from type i to type ii but not with a model involving different coupled substitutions and fluids from different origins we propose that the complex ree and isotopic signatures of scheelite at mt charlotte are related to small m to medium km scale processes involving mixing between fresh batches of hydrothermal fluid with fluids that had already been involved in extensive wall rock alteration the very high end values measured in some scheelites have been previously used to link gold mineralisation with komatiites containing unusually high sm nd ratios however tiny 20 m grains of secondary hydroxyl bastnasite were found within micro fractures of one scheelite grain containing an extremely high end signature the hydroxyl bastnasite probably formed during recent ree redistribution within the scheelite as a result of meteoric fluid circulation the scale of this cryptic low temperature alteration is sufficient to explain the anomalously high endi values observed in scheelite from western australia

formation of extremely f rich hydrous melt fractions and hydrothermal fluids during differentiation of highly evolved tin granite magmas a melt fluid inclusion study quartz crystals from topaz zinnwaldite albite granites from zinnwald erzgebirge germany contain in addition to primary and secondary fluid inclusions fis abundant crystalline silicate melt inclusions mis with diameters up to 200 m these mis represent various stages of evolution of a highly evolved melt system that finally gave rise to granite related sn w mineralization the combination of special experimental techniques with confocal laser raman microprobe spectroscopy and empa permits precise measurement of elevated contents of h2o f and b in re homogenized mis the contents of h2o and f were observed to increase from 3 to 30 and 1 9 to 6 4 wt respectively during magma differentiation however there is a second mi group very rich in h2o with values up to 55 wt h2o and an f concentration of approximately 3 wt ongoing enrichment of volatiles h2o f b and cl and of cs and rb can be explained in terms of magma differentiation triggered by fractional crystallization and thus is suggested to reflect elemental abundances in natural magmas and not boundary layer melts partitioning between melt and cogenetic fluids has further modified the magmatic concentrations of some elements particularly sn the coexistence of two types of mis with primary fis indicates fluid saturation early in the history of magma crystallization connected with a continuous sequestration of sn f and b the results of this study provide additional evidence for the extraordinary importance of the interplay of h2o f and b in the enrichment of sn during magma differentiation by decreasing the viscosity of and increasing the diffusivity in the melts as well as by the formation of various stable fluoride complexes in the melt and coexisting fluid

the geochemistry of zoning in skarn minerals at the king island dolphin mine trends of chemical zoning in crystals of garnet pyroxene scheelite and amphibole in 34 samples collected from the pluton9s contact updip to 500 m from the contact in the main ore horizon at the king islnd scheelite dolphin mine show systematic variations garnet cores up to 400 m from the contact are the most andradite rich reaching values of 98 mole percent nearest the contact andradite values decrease systematically both for a particular part of the garnet crystals away from the contact and across individual grains to the outer edges the mole percent andradite in core and outer core zones decreases to the 500 m mark while in the midsection and edge zones the values decrease to 400 m and then increase a similar relationship occurs in pyroxenes which nearest the contact contain hedenbergite values of 98 mole percent scheelite occurring as inclusions in garnet reach values of scheelite 65 powellites 34 for core zones nearest the pluton while scheelite interstitial to garnet have maximum values of scheelite 72 powellite 27 powellite contents decrease both toward the edges of individual grains and along the traverse to the 400 m mark where a reversal of trend occurs continuing to 500 m from the contact amphibole compositions show a linear decrease of the ratio fe super 2 fe super 2 mg mn from 98 nearest the contact to 88 at 390 and then decreasing abruptly to 65 at 500 m fluid inclusion filling temperatures vary systematically in time and distance from the pluton with a maximum near 800 degrees c for garnet midsections nearest the pluton to temperatures as low as 180 degrees c for interstitial calcite and quartz the salinities decrease from near 65 weight percent total dissolved salts in the early formed minerals i e garnet nearest the pluton to less than 3 weight percent for later formed minerals farthest from the contact i e calcite these decreases occur out from the contact and progressively toward the end of the paragenetic sequence scheelite initially crystallized at higher temperatures but interstitial scheelite precipitation occurred from a concentrated na k ca cl solution approximately 10 molal total dissolved salts at temperatures of approximately 500 degrees c at the pluton9s contact to 300 degrees c at a distance of 500 m from the contact chemical variations of fluid compositions for all but garnet core zones beyond 400 m from the contact occurred due to mixing of solutions derived from the northern boundary fault the interface between solutions which have permeated through and reacted with the developing skarn unit and those derived from the fault marks the maximum outward edge from the pluton of boiling of the solutions the highest concentrations of w ore reversals or inflection points in mineral composition profiles and changes in the elemental ratios of constituents in the brine solutions hot saline solutions initially cooled to approximately 380 degrees c on entering the colder marble horizon flow along this horizon caused the loss of heat dilution and chemical change of the solution this latter in response to both reactions with the marble and hornfelsic units as well as the precipitation of the skarn permeability was produced by the dissolution of caco 3 to produce cacl sub 2 aq and faulting with time thermal equilibrium was reached between the evolving fluid and the contact rocks until boiling of the solution occurred with the loss of a co sub 2 rich vapor during this event the northern boundary fault was tectonically active so that primary fluid now entered the forming skarn both from the fault and the contact of the pluton mo rich scheelite began to precipitate at the time of boiling subsequent to garnet pyroxene crystallization after the boiling event and contemporaneous with the crystallization of amphibole some quartz mo rich scheelite not armored in garnet was dissolved redistributed and redeposited as mo poor scheelite and molybdenite this type of scheelite forms most of the ore being mined

genesis of a magmatic metamorphic hydrothermal system the sn w polymetallic deposits at pilok thailand cassiterite wolframite and base metal mineralization in the pilok area are hosted by veins and stockworks in the apical portion of leucocratic granite stocks close to their contacts with pelitic metasedimentary rocks a minimum pressure of emplacement of approximately 1 500 bars is indicated by the presence of two coexisting feldspars in the granites and a moderate depth is supported by a lack of coeval volcanism and absence of porphyritic textures that characterize hypabyssal intrusions a contact metamorphic metasomatic aureole in the surrounding pelitic metasediments consists of tourmaline biotite and muscovite zones that are superimposed on muscovite chlorite zone regional metamorphism whole rock carbon analyses demonstrate a volatilization of graphite in the metasediments as a function of distance from the intrusion and the presence of andalusite in the aureole constrains the maximum pressure to approximately 3 800 bars the earliest mineralization is late magmatic to early postmagmatic wolframite cassiterite intergrown with li and f rich muscovite in pegmatite pods the bulk of the wolframite mineralization was subsequently deposited in veins with potassic alteration which could have originated either by orthomagmatic or remobilization processes finally cassiterite and sulfides chalcopyrite sphalerite were deposited in association with greisen alteration and formed as a result of the remobilization of tin from the host granite fluid inclusion and stable isotope data indicate the involvement of at least four fluid types a moderately saline fluid of presumed magmatic origin aqueous carbonic metamorphic fluids low temperature and low salinity meteoric fluids and high salinity formational or metamorphic fluids the isotopic compositions of waters calculated from delta o 18 analyses of quartz muscovite and cassiterite and delta d analyses of muscovite range from 1 4 to 9 4 and 63 to 118 per mil respectively these are consistent with the mixing of magmatic and organic rich metamorphic fluids oxygen isotope thermometry indicates temperatures of 350 degrees to 500 degrees c for cassiterite mineralization the oldest preserved fluid inclusions are primary aqueous carbonic inclusions from wolframite and cassiterite mineralization both the homogenization of the carbonic phase and the bulk

sm nd systematics of hydrothermal scheelite from the mount charlotte mine kalgoorlie western australia an isotopic link between gold mineralization and komatiites

ree fractionation between scheelite and apatite in hydrothermal conditions the geochemical analysis of hydrothermal apatite and scheelite pairs from various types of w ore deposits skarns disseminated scheelite and quartz veins provides an insight into ree partitioning between the two minerals among the 18 analyzed pairs only five appear to have grown in equilibrium conditions ten other pairs show more or less important departures from equilibrium the remaining apatite and scheelite pairs have quite different ree patterns indicating crystallization from different fluids both minerals concentrate ree the relative behavior of hree and lree is quite similar in the two minerals scheelite is only slightly more enriched in hree relative to lree than apatite with k ap sch la yb 0 86 0 22 beside these regularities some dispersion in the lanthanide content ratios of apatite and scheelite ranging from 0 6 to 5 may be related to fluid composition the behavior of eu can be related to redox conditions which appear to be more oxidizing in vein associations than in skarn environments determination of ree in coexisting scheelite and apatite seems an efficient tool for identification of successive ore bearing fluids

a nonlinear model of the shoaling and refraction of interfacial solitary waves in the ocean part i development of the model and investigations of the shoaling effect abstract oceanic internal waves are frequently observed to be of large amplitude and to exhibit significant wave front curvature as seen in synthetic aperture radar images the aim of this paper is to present a refraction model in two horizontal dimensions including moderate amplitude effects to model these common properties of internal waves the model incorporates second order nonlinearity and uses a ray method to allow arbitrary refraction for these preliminary investigations with the model a two layer ocean is assumed with an upper layer thickness of 50 m and a density difference across the layers of 0 5 kg m 3 an important aspect affecting the refraction of nonlinear waves is shoaling as the phase speed of a nonlinear wave depends on its amplitude in part i of this paper the development of the model is described and the shoaling phenomenon is investigated in detail the shoaling of interfacial internal solitary waves over both slowly varying and rapidly varying bathymetry is studied a wedg

structural development of the lower paleozoic belt of south china genesis of an intracontinental orogen abstract an extensive structural study of wuyishan and surrounding areas south china brings data on the structures formed prior to the devonian unconformity building the lower paleozoic belt an ordovician tectonic event was responsible for i south directed structures in the wuyishan proper and its southern border related to both thin and thick skinned tectonics accompanied by metamorphism and crustal thickening ii north directed structures to the west of ganjiang fault and north of jiangshan shaoxing fault where only thin skinned tectonics is visible the southward deformation accommodating the shortening includes emplacement of thrust sheets involving deep crustal material and some mantle peridotite and likely repetition of continental material both responsible for crustal thickening the orogeny was due to the underthrusting of the southern part of the south china block beneath the northern part of this block closing the pre existing nanhua rift created at around 850 800 ma and involving the rift sedimentary fill in the southward thrusting the syn metamorphic tectonic piling was followed by anatexis and granite emplacement at around 440 390 ma our new u th pb epma monazite dating gives ages of 433 9 ma and 437 5 ma early silurian for the main anatectic event and a younger age of 412 5 ma late silurian early devonian for a late re heating process the lower paleozoic belt is an intracontinental orogen without oceanic suture record it shows some similarities with the cenozoic european pyrenees chain with a strong asymmetry

onland signatures of the palawan microcontinental block and philippine mobile belt collision and crustal growth process a review abstract the collision of the palawan microcontinental block with the philippine mobile belt had significantly influenced the geological evolution of the philippines multiple collisions involving several fragments through space and time resulted into the collage of terranes of varying origin exposed in this part of central philippines cusping of the overriding plate volcanic arc gap ophiolite emplacement incipient back arc rifting island rotation and tilting raised coastal terraces metamorphism intrusion of igneous rocks and steepened subducted slab as seen in focal mechanism solutions are some of the manifestations of this collision a late early miocene to early middle miocene age 20 16 ma is proposed for the major collision between the palawan indenter and the philippine mobile belt the collision boundary is located from the northern part of mindoro through the central mountain range swinging east of sibuyan island in the romblon island group and finally threading along the buruanga peninsula and eastern side of the antique ophiolite complex before exiting and connecting with the negros trench the collision through accretion and crustal thickening has contributed to the crustal growth of the philippine archipelago

nb ta fractionation in peraluminous granites a marker of the magmatic hydrothermal transition in their late stages of evolution peraluminous granitic melts exsolve large amounts of fluidswhich can modify the chemical composition of granitic whole rock samples the niobium tantalum nb ta ratio is expected to decrease during the magmatic differentiation of graniticmelts but the behavior of both elements at the magmatic hydrothermal transition remainsunclear using a compilation of whole rock geochemical data available in the literature wedemonstrate that fractional crystallization alone is not sufficient to explain the distribution ofnb ta in most peraluminous granites however we notice that most of the granitic samplesdisplaying evidence of interactions with fluids have nb ta 5 we propose that the decreaseof the nb ta ratio in evolved melts is the consequence of both fractional crystallization andsub solidus hydrothermal alteration we suggest that the nb ta value of 5 fingerprints themagmatic hydrothermal transition in peraluminous granites furthermore a nb ta ratio of 5appears to be a good marker to discriminate mineralized from barren peraluminous granites

strontium isotope systematics of hydrothermal minerals from epigenetic archean gold deposits in the yilgarn block western australia strontium isotope compositions are presented for samples of hydrothermal scheelite and tourmaline from one granitoid hosted and 14 greenstone hosted archean gold deposits in the yilgarn block western australia the direct measurement of the 87 sr 86 sr ratios of rb poor minerals such as scheelite and tourmaline which show an intimate paragenetic relationship to gold allows an accurate estimate of the local strontium isotope composition of the archean gold bearing hydrothermal fluids the population of greenstone hosted gold deposits is sub divided according to gangue mineralogy into gold skarns with garnet pyroxene biotite and amphibole biotite calcite wall rock alteration which formed in the lower parts of the green stone belts at depths of 10 to 15 km and medium temperature gold deposits with biotite or sericite ankerite albite wall rock alteration which formed in the upper parts of the belts at depths of 3 to 7 km the 87 sr 86 sr ratios of the fluids vary from 0 7020 to 0 7035 in skarns with garnet pyroxene biotite alteration from 0 7020 to 0 7043 in skarn quartz orebodies with amphibole biotite calcite alteration and from 0 7014 to 0 7028 in the medium temperature gold deposits the variations in the strontium isotope composition of scheelite from the same mining district are interpreted to reflect mixing between radiogenic strontium introduced by the hydrothermal fluid and nonradiogenic strontium released from the wall rocks during interaction with this fluid the greenstone host rocks of all deposits mainly metamorphosed ultramafic or mafic volcanic rocks and their intrusive equivalents are characterized by the low initial 87 sr 86 sr ratio 0 7007 0 7012 and low rb sr ratio of the archean mantle on the other hand the initial 87 sr 86 sr ratios of granodiorite and granite plutons in the batholiths which underlie and border the greenstone belts vary from 0 7023 to 0 7044 the strontium isotope data indicate that the deep seated gold skarns formed predominantly from fluids which evolved from or interacted with anatectic magmas in the granitoid batholiths the data do not as clearly constrain the origin of the fluids in the higher level medium temperature hydrothermal systems they are however inconsistent with models involving predominantly metamorphic fluids generated by the devolatilization of the lower parts of the greenstone belts

origin and evolution of ore forming fluids of the larong w mo deposit eastern tibet constraints from fluid inclusions h o isotopes and scheelite geochemistry abstract the larong porphyry w mo deposit formed in the main collisional orogenic stage of lhasa and qiangtang terranes is the first discovered giant w mo deposit in the leiwuqi zogang metallogenic belt sanjiang region the w mo mineralization occurs as veins and stock works mainly hosted in the granodiorite porphyry monzogranite porphyry biotite granite porphyry and surrounding schist four types of fluid inclusions fis including pc type pure vapor co2 c type co2 h2o w type aqueous two phase and l type pure liquid h2o fis have been identified from stage i quartz scheelite alkaline feldspar veins stage ii including three sub stages quartz molybdenite pyrite chalcopyrite veins and stage iii quartz calcite pyrite veins the total homogenization temperatures of fis vary widely 187 437 c with multiple peaks indicating multistage fluid activities the ore forming fluids of the main mineralization stages are characterized by co2 enrichment high medium temperature 270 440 c and medium low salinity 2 4 14 4 wt nacl equiv the homogenization temperature of w type inclusions is obviously higher than that of c type inclusions and the salinity is relatively lower implying multiple immiscibility of fluids with continuous escape of co2 h o isotopic compositions suggest that the primary ore forming fluids dominantly originated from magma water mo concentrations and eu values in scheelite indicate a decreasing trend of redox state of ore fluids from stage i to stage ii to stage iii the relatively higher temperature co2 rich and oxidized fluids gradually evolved into relatively lower temperature co2 poor and reduced fluids here we propose that the decrease of temperature and oxygen fugacity and increase of s2 activity and ph values of the ore fluids caused by continuous fluid rock interaction and loss of co2 could account for the successive mineralization of w and mo at the larong deposit

chemical differentiation of obsidian within the glass buttes complex oregon two hundred twenty five source samples from the multi component obsidian source at glass buttes oregon were characterized by neutron activation analysis to determine the number of chemical groups present seven geochemical groups were found within the glass buttes complex an abbreviated neutron activation analysis procedure previously used to differentiate between obsidian sources in mesoamerica was also successful in separating obsidian from different outcrops at glass buttes thirty one artifacts from the robins spring site on glass buttes were also analysed the abbreviated naa procedure was also successful at assigning the artifacts to the different subsources at glass buttes

reasserting the utility of obsidian hydration dating a temperature dependent empirical approach to practical temporal resolution with archaeological obsidians in a recent paper in this journal anovitz et al 1999 identify potentially serious flaws in the measurement and modelling of obsidian hydration for dating archaeological obsidians this critique follows other recent papers highlighting potential problems with the method e g ridings 1996 stevenson mazer scheetz 1998 contrary to this latest critique the current paper offers evidence for the apparent efficacy of a quadratic model for obsidian hydration dating of archaeological obsidians using empirical results from archaeological projects throughout the western united states it is posited that this model is sufficient in part due to limits of commonly used methods of hydration analysis which also provide a cost effective means for large scale sampling given apparent support for quadratic modelling and hence the diffusion theory underlying it an empirical approach to obsidian hydration rate formulation that incorporates field temperature data is explored although evaluation of the resulting rate formula for casa diablo obsidian is somewhat equivocal the results are relatively robust when compared to other posited rates as such the approach appears to hold promise within the limits of temporal resolution necessary for many regional research strategies while also serving as a potential check of laboratory based strategies

the logtung large tonnage low grade w scheelite mo porphyry deposit south central yukon territory mineralization is related to multiple felsic intrusions since mineralization is contained in fractures 95 rather than being disseminated logtung is not a skarn deposit the principal reason is that the reaction skarn host rocks which were derived from calcareous shales interbedded with graphitic quartzites are carbonate poor and competent hence permeable mineralization formed in permeability created by hydraulic fracturing and not by replacement logtung shows a scheme of several phases 4 of mineralization related to multiple intrusions which is similar to that which is so important in for example the evolution of the climax and urad henderson mo systems the logtung deposit shows many similarities to porphyry mo deposits in the western cordillera and may be classed as a porphyry w scheelite mo deposit with a w mo ratio of 3 3 1 0 the principal reasons are that mineralization is spatially associated with porphyritic intrusive phases and that much of the mineralization occurs as typical porphyry style crackle breccias modified journal abstract

scheelite elemental and isotopic signatures implications for the genesis of skarn type w mo deposits in the chizhou area anhui province eastern china scheelite is well developed in hydrothermal deposits providing a window into genetic processes and facilitating comparative studies however few studies have focused on characterizing scheelite in skarn type w mo deposits the primary ore mineral in the jitoushan and baizhangyan skarn type w mo deposits anhui province eastern china scheelite was analyzed for major trace and rare earth element ree abundance and for sr nd isotopes the analysis revealed two unique geochemical characteristics that distinguish the scheelite from skarn type w mo deposits to that from vein type au w and porphyry type w mo deposits higher mo content with a negative correlation between moo 3 and wo 3 and a strong hree depletion skarn type scheelite mainly inherited ree signatures from ore forming fluids and the early precipitation of skarn minerals e g garnet diopside and amphibole has most likely resulted in the observed strong hree depletion in scheelite and the decoupling of lrees and hrees of the numerous substitution mechanisms suggested by previous workers 3ca 2 2ree 3 ca where ca is a ca site vacancy is preferred for the substitution of ree 3 for ca 2 and in this study particularly given the low salinity of ore fluids as the scheelite eu anomalies were inherited from ore forming fluids with variable redox conditions and ph the complex deu mo correlation indicates that mo increasingly entered the scheelite under oxidizing conditions and reached a maxim at deu values of 0 8 to 1 in contrast under reducing conditions mo contents in scheelite decrease gradually and mo is precipitated as molybdenite as a result of the change in dominant valence state unlike the sr nd isotope compositions of scheelite from vein type au w and w sb au deposits the scheelite from skarn type w mo deposits has low 143 nd 144 nd t most 87 sr 86 sr t values most between 0 708 and 0 715 the end t values of the scheelite varied from 16 to 12 3 in the baizhangyan deposit and from 9 5 to 9 1 in the jitoushan deposit indicating that the ore forming materials in the two w mo deposits were mainly derived from crustal sources

nd and sr isotope study of hydrothermal scheelite and host rocks at omai guiana shield implications for ore fluid source and flow path during the formation of orogenic gold deposits omai is a high tonnage low grade world class gold deposit located in the paleoproterozoic guiana shield it is the second most important gold deposit in the guiana shield after las cristinas venezuela and one of the largest in south america 4 0 million oz sm nd and sr isotope data are presented for host rocks and for scheelite from auriferous quartz carbonate scheelite sulfide telluride veins from the omai deposit gold bearing veins are hosted by the paleoproterozoic barama mazaruni supergroup a greenstone belt sequence consisting of mafic volcanic rocks interbedded with sedimentary rocks that are intruded by quartz feldspar porphyry and rhyolite dikes this lithologic sequence was folded and metamorphosed to lower greenschist facies during the paleoproterozoic trans amazonian orogeny the volcano sedimentary unit was intruded by a post tectonic quartz monzodiorite diorite hornblendite stock initial nd isotope ratios for the omai volcanic rocks range from nd 2 1 to 4 2 these values suggest that this part of the guiana shield was a site of new crust formation during the paleoproterozoic and was not contaminated by older archean reworked continental crust initial nd isotope ratios for the omai stock range between 0 5 and 2 3 which suggest limited contamination with previously formed continental crust although the nd isotopic ratios of gold related scheelites overlap with those of the host rocks particularly the tholeiitic basalts at the interpreted time of vein emplacement the lack of both isotopic mixing and significant nd movement during the hydrothermal process suggest that the nd isotope composition can be used to determine the isotopic characteristics of the ore fluid source area at omai the ore fluid is largely derived from a radiogenic nd source represented by mantle or lower crustal reservoirs strontium isotope ratios for the scheelites cluster tightly between 0 7019 and 0 7021 the sr isotope data suggest that unlike nd sr was significantly mobile during the hydrothermal process the fluids responsible for the omai deposit may have picked up sr along the flow path the constant low sr isotope values of scheelites probably reflect the key role that the local tholeiitic basalts played as the main source of sr in the fluids whereas nd isotopes identify the fluid source area the sr isotopes map the fluid flow paths

pxrf characterisation of obsidian from central anatolia the aegean and central europe the obsidian sources of central anatolia the aegean and central europe have been studied in detail over the past 50 years various analytical techniques have been employed to discriminate artefacts from each of these and to reconstruct their zones of distribution this paper presents a pxrf method that allows mass sampling of artefacts focusing on three neighbouring regions particularly where these zones overlap successful discrimination of the obsidian source for products could be achieved using three dimensional scatter plots of trace elements rb sr zr pxrf can thus be appreciated as a powerful tool in the region enabling non destructive on site analyses in contexts where the export of artefacts is often difficult if not impossible the ability to rapidly process large assemblages also has major implications for generating data sets of sufficient resolution to transform archaeological interpretation

a nonlinear model of the shoaling and refraction of interfacial solitary waves in the ocean part ii oblique refraction across a continental slope and propagation over a seamount abstract the refraction of internal solitary waves can be due to variations in water depth nonlinearity stratification or shear this paper addresses the effects of the first two of these effects part i of this paper investigated how the amplitude and phase speed of an interfacial solitary wave varied as the wave propagated across a one dimensional slope important differences between the predictions of korteweg de vries kdv and extended kdv ekdv theory were found in particular the ekdv limited the amplitude growth seen in kdv as the wave passed into shallow water leading to an associated strong retardation in speed in this second part of the paper these results are applied to two dimensional bathymetry the propagation of an oblique planar wave across a wedge shaped slope is first studied whereas the linear internal wave theory predicts small refraction of the wave front the nonlinear ekdv model shows that the refraction of large amplitude internal waves is significantly greater this is exp

multiple stage tungsten mineralization in the silurian jiepai w skarn deposit south china insights from cathodoluminescence images trace elements and fluid inclusions of scheelite abstract the jiepai deposit located in the northeastern part of the miao ershan yuechengling batholith south china is characterized by predominant skarn mineralization that formed near the contact between the silurian biotite granites and the upper cambrian carbonate rocks jiepai scheelites are recognized as two main generations based on their occurrences cathodoluminescence cl signatures and ree systematics prograde skarn hosted scheelite i has uniformly dark cl characteristics and lree enriched patterns retrograde skarn hosted scheelite iia is homogeneously dark under cl and has a slightly mree enriched pattern whereas quartz vein hosted scheelite iib is delineated by fine oscillatory cl zones and a relatively flat ree pattern additionally the cl images reveal that both scheelite i and ii were modified by later stage hydrothermal overprints which occur as ubiquitous overgrowth rims and cutting veins with bright cl signatures low ree but similar ree patterns to their precursors the compositional variations and fluid inclusions in jiepai scheelites identify episodic pulses of hydrothermal fluids with different properties the ore forming fluids with high nb ta but low nb ta and rey in the early retrograde stage are featured by moderate to high temperature and low to moderate salinity under relatively oxidizing conditions they interacted with the host rock and underwent boiling to precipitate scheelite i by contrast the fluids with higher nb ta and rey but lower nb ta in the late retrograde stage have slightly lower temperature and higher salinity we therefore speculate that scheelite ii may deposit from later magmatic fluids that have experienced continued boiling in more reducing environment

distortion and broadening of internal solitary wavefront in the northeastern south china sea deep basin internal solitary waves isws with peculiar fronts are frequently observed in the world ocean by satellite images though with quite few explanations in this study a distorted and broadening isw front across the northeastern south china sea deep basin is presented by using synthetic aperture radar sar image to illustrate this peculiar front a nonlinear refraction model is developed to simulate and evaluate the effects of realistic bottom topography current and stratification on its transformation simulated results in realistic oceanic environments show good agreements with this sar observed front based on separate and comparative results in different background environments we demonstrate that the distortion is actually caused by the strong mesoscale currents at periphery of an anticyclonic eddy moreover the broadening is due to the difference in change of wave half width at different rays which is associated with the different transformation of isws across variable bottom topography in the deep basin

analysis of nonlinear internal waves in the new york bight this paper presents the results on internal wave analysis of the current meter mooring data in the new york bight from the sar internal wave signature experiment sarsex selective sets of current and temperature measurements are analyzed for a parametric study of internal wave characteristics and shear effects on wave parameters are studied based on the limited data from moorings the solitary wave theory has been extended for the wave evolution on a continental shelf by including dissipation and shoaling effects a series of numerical simulations are performed to demonstrate the relative importance of dissipation and shoaling effects from an observed initial wave packet at the upstream mooring the numerical evolution simulation compares reasonably well with the measurements at the distant mooring for the leading two large solitons

internal solitons on the pycnocline generation propagation and shoaling and breaking over a slope in part 1 a study is made of the internal solitary wave on the pycnocline of a continuously stratified fluid a korteweg de vries kdv equation for the interfacial displacement is developed following benney s method for long nonlinear waves experiments were conducted in a long wave tank with the pycnocline at several different depths below the free surface while keeping the total depth approximately constant a step like pool of light water trapped behind a sliding gate served as the initial disturbance condition the number of solitons generated was verified to satisfy the prediction of inverse scattering theory the fully developed soliton was found to satisfy the kdv theory for all ratios of upper layer thickness to total depth in part 2 of this study we investigate experimentally the evolution and breaking of an internal solitary wave as it shoals on a sloping bottom connecting the deeper region where the waves were generated to a shallower shelf region it is found through quantitative measurements that the onset of wave breaking was governed by shear instability which was initiated when the local gradient richardson number became less than the internal solitary wave of depression was found to steepen at the back of the wave before breaking in contrast with waves of elevation two slopes were used with ratios 1 16 and 1 9 and the fluid was a boussinesq fluid with weak stratification using brine solutions

obsidian sources and distribution systems in island southeast asia new results and implications from geochemical research using la icpms this paper discusses new evidence of long distance interaction networks in island southeast asia obtained from geochemical analyses using sem edxa and la icpms of 101 obsidian samples from 25 locations including seven obsidian sources and 19 archaeological sites given that there are obsidian sources distributed throughout much of island southeast asia the potential for obsidian studies to provide greater understanding of patterns of mobility and exchange in the pre neolithic and neolithic periods would seem to be considerable this potential however remains largely unrealised as obsidian sourcing has hitherto only been carried out intermittently in island southeast asia using pixe pigme xrf and other methods

ore genesis and fluid evolution of the qiaomaishan cu w deposit in the middle lower yangtze river metallogenic belt evidence from in situ analyses of apatite and scheelite abstract the newly exploited qiaomaishan skarn type cu w deposit located in the xuancheng ore cluster district in the middle lower yangtze river metallogenic belt mlyrb is one of the few tungsten polymetallic deposits in this region this study conducted a series of in situ analyses of elements and isotopes for apatite scheelites and sulfides aiming to provide new insights into the source hydrothermal ore forming processes fluid evolution history and genesis of this deposit and important knowledge to investigate regional tungsten mineralization events in the mlyrb apatite geochemistry shows that the early magma source of the ore related rocks in qiaomaishan obviously displayed adakitic affinity with high oxygen fugacity and featured fluorine rich fluids originating from a w rich mixed source the tungsten mineralization is dominated by scheelite in the qiaomaishan deposit based on microscopic observations and in situ analysis two types of scheelite with different geochemical characteristics were recognized two types of scheelite in the qiaomaishan have controlled by different mechanism of ree substitutions scheelite i occurs in the sulfide stage and displays high na and ree concentrations downwards sloping ree fractionation trends with negative eu anomalies and 87sr 86sr ratios 0 70945 0 71033 similar to those of ore related granodiorite porphyry however scheelite ii shows relatively low ree concentrations high na contents mree rich patterns with positive eu anomalies and high 87sr 86sr ratios 0 71477 0 72352 distinct eu anomalies and sr concentrations of the two types of scheelite and s isotopes of sulfides indicate that the early stage fluids were inherited from the primary granodioritic magmatic hydrothermal fluids however the late stage fluids were modified by intense fluid rock interactions and inputs from the host gypsum bearing carbonates collectively the f and w rich sources intense fluid rock interactions and changes in oxidation reduction conditions favoured tungsten mineralization which resulted in the formation of the qiaomaishan tungsten deposit

possible obsidian sources for artifacts from timor narrowing the options using chemical data measurements made at the australian national university using laser ablation icpms show that none of the 88 analyzed obsidian artifacts from east timor match either the known papua new guinea or the five island se asian source samples in our anu collections there is a coastal journey of more than 3000 km between the occurrence of obsidians from the bismarck archipelago volcanic province of papua new guinea and the sunda banda arc volcanic chain yet obsidian artifacts from the two important png sources of talasea and lou island are found at coastal bukit tengkorak in eastern sabah at a similar distance along with material that has no known source timor lies south of the eastern section of the active volcanic banda arc island chain but it is within range of possible rhyolite sources from there although there is a continuous chain of around 60 active volcanoes stretching from west sumatra to the moluccas most are basaltic to andesitic with few areas likely to produce high silica dacite rhyolite deposits this does not exclude the possibility that the volcanic landscapes may contain obsidian but without detailed survey and chemical analysis of sources from the sunda banda arc the attribution of the timor obsidian artifacts remains to be demonstrated timor may seem to be an unlikely source for the presence of obsidians as it lacks reports of the silica rich rhyolite volcanic centers necessary to produce this material despite the absence of detailed survey and analysis of indonesian obsidian sources especially from the volcanically active banda arc this paper presents evidence that one of two obsidian sources is clearly from timor while the other with less certainty is also from an unknown local source

intrasource chemical variability of artefact quality obsidians from the casa diablo area california abstract obsidian from the casa diablo area of mono county california was an important source for artefacts and raw material in prehistoric california although little work has been devoted to investigating the potential geochemical variability within the many quarry areas it contains in this study 200 obsidian source samples from 20 collection locations in the casa diablo area were analysed by energy dispersive x ray fluorescence spectrometry laboratory analyses of solid flake and powdered obsidian samples are presented in quantitative measurement units parts per million and or weight percent composition calibrated to international rock standards the results of this research indicate that two possibly three geochemically distinct varieties of artefact calibre obsidian exist within the source area once believed by archaeologists to be a single geochemical entity these new findings carry implications for obsidian trade exchange systems studies in california and the great basin and for obsidian sourcing research in other areas of the world

effects of topography and earth s rotation on the oblique interaction of internal solitary like waves in the andaman sea high resolution three dimensional mitgcm simulations and an extended miles theory are used to investigate the oblique interaction of internal solitary like waves isws in the andaman sea oblique solitary wave interaction is well studied in various fields of physics however this process in the ocean has seldom been investigated despite the observations of its surface signature by remote sensing and potential 4 fold increase of isw amplitude by the development of a mach stem this study confirms the development of stem like isws under realistic oceanic conditions the modeled interaction is found to be approximately consistent with the miles theory extended to unequal incident wave amplitudes and small but finite incident angles although topography does not appear to affect the process in the deep part of the andaman sea substantial topographic amplitude variation along the wave trough needs to be adjusted before comparisons with the theory earth s rotation has a small effect on isw propagation due to the low latitude 9 n but it does slow down the growth of stem like isws potential observation of the process by the next generation wide swath satellite altimeter is discussed

formation of anhydrous and hydrous skarn in cu au ore deposits by magmatic fluids most skarn ore deposits are characterized by two distinctly different alteration styles an early prograde stage with anhydrous minerals such as garnet and pyroxene forms from relatively high temperature hypersaline liquid a later retrograde stage with hydrous minerals such as epidote amphibole and chlorite plus sulfide ore minerals forms from lower temperature lower salinity fluids these two alteration stages commonly have been thought to reflect a dominance of magmatic and meteoric water respectively with relevance to the source of ore metals we report data from two different skarn systems one being part of the world s largest cu au resource stable isotope compositions of anhydrous and hydrous alteration minerals from both deposits indicate a magmatic source for both the prograde and retrograde stages 18o averages 5 0 per mil for garnet range 3 4 7 2 6 5 per mil for pyroxene 4 3 8 2 and 7 1 per mil for amphibole 4 3 8 7 the d values of late amphibole are more complex with magmatic values 77 to 78 for one deposit and both magmatic and lighter values for another deposit that could be explained either by magmatic degassing or by limited mixing with meteoric water we conclude that the differences in fluid composition prograde versus retrograde stages resulted from a magmatic fluid that intersected its solvus during the early stage creating vapor and hypersaline liquid whereas in the later stage this magmatic fluid did not intersect its solvus because it followed a different cooling path this late low salinity liquid only boiled once its vapor pressure curve was reached causing sulfide ore to precipitate during the retrograde stage

rare earth element geochemistry and fluid characteristics of scheelite in the hutti gold deposit hutti maski schist belt raichur district karnataka india abstract scheelite occurs as thin smears isolated grains and veinlets in auriferous quartz reefs and sulfidized and auriferous biotite chlorite schist in the hutti deposit major host rocks at hutti are mafic and sill like felsic volcanic rocks and quartz reefs located at the shear contact of these rocks laser raman and fluid inclusion studies on scheelite show that h2o ch4 co2 nacl fluids similar to gold mineralizing fluid are responsible for scheelite mineralization at hutti rare earth element ree geochemistry of scheelite shows two types of chondrite normalized ree patterns which are classified as type i hump shaped pattern characteristic of ree incorporation by coupled substitution involving na or k and type ii flat pattern involving ree substitution with creation of a vacancy the type i pattern is seen in scheelite within biotite schists whereas type ii pattern is associated with scheelite in felsic volcanic rocks and quartz mylonites the type ii pattern is subdivided into type iia and type iib pattern based on eu eu values with type iia showing larger eu eu values than type iib the lower ratio in type iib scheelite which occurs in altered felsic volcanic rocks is attributed to the overall enhancement of mree due to some degree of coupled substitution involving na relative to type iia the slope of the ree distribution pattern of scheelite is distinctly different from that of felsic volcanic rocks but similar to that of mafic volcanic rocks it is inferred that ree fractionation between mineralizing fluids and greenschist facies metamorphosed mafic rocks of the schist belt is not significant

dating scheelite stages a strontium neodymium lead approach from the felhertal tungsten deposit central alps austria abstract new sm nd rb sr and pb pb isotope data of scheelites and their host rocks from the felbertal scheelite deposit central tauern window eastern alps austria are presented the oldest stage 1 scheelites are rarely preserved they plot together with recrystallized stage 2 scheelite porphyroblasts on a sm nd isochron of 581 105 ma this sm nd age is regarded as the time of the primary tungsten mineralization our interpretation is enhanced by a within error limits similar age of 517 114 ma derived from a 207pb 206pb scheelite isochron and a date of 517 130 ma obtained from two co genetic relics a clinopyroxene and a tschermakitic amphibole within a metapyroxenite the stage 2 scheelite blastesis was possibly triggered by an still unassured ordovician caledonian metamorphism and further promoted by a carboniferous granitoid intrusion and a variscan metamorphism without an isotopic reset both yellowish fluorescent mo bearing stage 1 and stage 2 scheelites were formed under oxidizing alkaline conditions which obviously did not promote ree fractionation and did not disturb the original sm nd isotopic system this evidently was not the case during younger remobilizations in late variscan and alpine metamorphic times when stage 3 319 34 ma and stage 4 29 17 ma scheelites formed both stages consist of bluish fluorescent mopoor to mo free scheelites that reveal significant ree depletion and fractionation probably due to repeated corrosion and re precipitation under more reducing neutral to slightly acidic conditions the source and mechanism of deposition of the primary tungsten mineralization are deduced from five facts 1 the radiogenic strontium isotopic data of stage 1 scheelites 87 sr 86 sr 0 726 0 730 occurring together with normal crustal neodymium isotopic compositions echurt 1 3 8 to 7 3 2 unusually high u concentrations up to 74 ppm in stage 1 scheelites 3 a sudden 87sr increase between the formation of magmatic clinopyroxene 87sr 86srt 0 707 considered to have precipitated within a magma chamber and of ubiquitous tschermakitic hornblende 87 sr 86 sr t 0 736 interpreted as subsolidus mineralization during infiltration of a hydrous fluid 4 an extraordinary enrichment of cesium a lesser but still significant enrichment of rubidium and lithium and normal arc like contents of potassium in the mafites 5 the lead isotopic compositions of the scheelites and their host rocks the latter indicate a mantle signature overprinted by a crustal component at an active continental margin we suggest that a midlevel crustal position in an active continental margin setting is the most probable site for the primary tungsten source tungsten bearing ascending fluids from dehydrated granulites with mica breakdown reactions established a convective fluid system supported by gabbroic and co eval granitoid intrusions we assume that a rock mass of some 103 km3 may have undergone granulite facies reactions with fluid formation to provide the total tungsten content of 200 000 tons in the felbertal deposit this would imply that the tungsten content in the released fluid has been some 100 ppm

observations of highly nonlinear internal solitons over the continental shelf surface disturbances caused by strong near surface internal waves are widely seen in coastal regions as bands of slick and rough water propagating shoreward these surface slicks are typically manifestations of optical and radar backscatter properties above internal solitons and have strong surface current pulses associated with them during a recent experiment studying coastal internal waves extremely strong solitary internal wave packets were observed over a three week period on a very shallow and strongly stratified pycnocline off northern oregon during periods of strongest tidal forcing solitons were consistently observed on the leading edge of a semidiurnal internal tide bore with pycnocline displacements up to 25m downward from a 7m initial depth in the first few solitons the extreme nonlinearity of these internal waves is believed to be unique in ocean observations this note characterizes these highly nonlinear solitary internal waves siw and presents a second order kdv model which reproduces the form of the displacements and the small change in soliton width with amplitude predicted by this model

how reliable are our published archaeometric analyses effects of analytical techniques through time on the elemental analysis of obsidians to assess the analytical accuracies and precisions of archaeometric elemental analyses by different techniques a relatively homogeneous material such as obsidian must be studied an assessment of published elemental concentration data from two anatolian obsidian sources shows that while in most cases analytical accuracy is as high as is commonly expected in some cases it is not it also shows that the dispersions of elemental concentration data indicators of analytical precisions coming from modern analytical procedures are akin to the estimated homogeneity of the obsidian based on this latter observation if one has element dispersion data from a single analytical technique with a single source of obsidian as a control data sets that contain multiple but similar sources of obsidian may be differentiated

late archean and early proterozoic gold tungsten mineralization in the zimbabwe archean craton rb sr and sm nd isotope constraints the sm nd technique has been successfully used to date scheelites from lode gold and tungsten deposits in the archean midlands greenstone belt zimbabwe two phases of mineralization have been established which correlate with late archean and early proterozoic magmatic events in the region the gold deposits are mainly structurally controlled and are spatially associated with high strain zones and internal synvolcanic to late tectonic tonalite plutons most gold bearing structures can be categorized into one of two preferred orientations parallel to acutely oblique with the main s1 fabric or crosscutting s1 at a high angle and striking parallel to locally developed d2 structures or fabrics sm nd dating of scheelite demonstrates that these two structural populations are characterized by discrete phases of gold mineralization the main s1 parallel gold deposition dated at 2 66 0 05 ga correlates with the late archean trondhjemite tonalite granodiorite event in zimbabwe the s1 discordant phase has yielded an age of 2 41 0 07 ga broadly corresponding to the timing of emplacement of the great dyke and reactivation of the late archean high strain zones sr isotope data provide important constraints on the evolution of the hydrothermal fluids

garnet and scheelite as indicators of multi stage tungsten mineralization in the huangshaping deposit southern hunan province china abstract the huangshaping w mo pb zn deposit in southern hunan province south china contains multiple generations of garnet and scheelite in skarn and sulfide carbonate altered rocks optical characteristics and chondrite normalized rare earth element reen patterns obtained by in situ laser ablation inductively coupled plasma mass spectrometry analysis were used to distinguish different generations of garnet and scheelite these data show a clear correspondence of garnet reen patterns to major element zonation with hrees e g gd lu being depleted overall coarse grained garnets in the huangshaping deposit have extreme hree depletions and significant lree e g la eu enrichment particularly for ce pr and nd this indicates that rees in these garnets are the result of coupled substitutions ca2 viii 1 ree3 viii 1 and fe2 iv 1 al3 iv 1 medium grained garnets have reen patterns showing significant lree enrichment and depleted hrees with high sn contents this suggests that substitution of rees in these garnets occurs as ca2 viii 1 ree3 viii 1 sn4 iv 1 al3 iv 1 the fact that medium grained garnets have high sn contents indicates mineralizing fluids were oxidizing which is consistent with significant positive eu anomalies however hump shaped reen patterns for garnet rims suggest substitution by ca2 viii 2 na viii 1 ree3 viii 1 where nd tb are preferentially incorporated into the garnet lattice over other rees group 1a scheelite has black cores in cathodoluminescence images and reen patterns showing extreme lree enrichment and hree depletion group 1b scheelite has cores with fine oscillatory zoning and enriched lrees with depleted hrees similar to the reen patterns of group 2a scheelite that occur as rims with bright cl surrounding both group 1a and 1b scheelite the substitution mechanism for rees in these three types of scheelite is ca2 viii 3 viii 1 ree3 viii 2 with being a ca site vacancy the influence of ree speciation in the hydrothermal fluid dominates the reen patterns of these types of scheelite however for group 2b bright rims of scheelite rees are incorporated as ca2 viii 2 na viii 1 ree3 viii 1 similar to the garnet rims finally scheelite mo contents and eu values that decrease from group 1a to 2b support a temporal decrease in oxygen fugacity of the mineralizing fluids ratios of y ho and mo contents that decrease from group 1a and 1b to group 2a and 2b scheelites are similar to those in porphyry related skarn w mo and quartz vein au w deposits respectively our studies also suggest that all these scheelites in this deposit formed from magmatic fluids at the huangshaping deposit medium grained garnets associated with group 1a scheelite precipitated from evolved magmatic fluids during prograde metamorphism as indicated by their complementary y ho ratios paragentically younger scheelite particularly group 2b may have formed from dilute magmatic fluids that underwent large scale hydrothermal circulation the characteristics of group 1b and 2a scheelite likely reflect a transitional environment and fluid mixing during tungsten mineralization in the polymetallic huangshaping deposit

simulation of the transformation of internal solitary waves on oceanic shelves abstract internal solitary waves transform as they propagate shoreward over the continental shelf into the coastal zone from a combination of the horizontal variability of the oceanic hydrology density and current stratification and the variable depth if this background environment varies sufficiently slowly in comparison with an individual solitary wave then that wave possesses a soliton like form with varying amplitude and phase this stage is studied in detail in the framework of the variable coefficient extended korteweg de vries equation where the variation of the solitary wave parameters can be described analytically through an asymptotic description as a slowly varying solitary wave direct numerical simulation of the variable coefficient extended korteweg de vries equation is performed for several oceanic shelves north west shelf of australia malin shelf edge and arctic shelf to demonstrate the applicability of the asymptotic theory it is shown that the solitary wave may maintain its sol

re os sm nd u pb and stepwise lead leaching isotope systematics in shear zone hosted gold mineralization genetic tracing and age constraints of crustal hydrothermal activity abstract a combined re os sm nd u pb and stepwise pb leaching pbsl isotope study of hydrothermal mo w bearing minerals and base metal sulfides from two adjacent shear zone hosted gold deposits ran kimberley in the harare shamva greenstone belt zimbabwe constrain the timing of the mineralizing events to two periods during an initial late archean event 2 60 ga a first molybdenite scheelite bearing paragenesis was deposited in both shear zone systems followed by a local reactivation of the shear systems during an early proterozoic 1 96 ga tectono thermal overprint during which base metal sulfides and most of the gold was re deposited while pbsl has revealed an open system behavior of the u pb systematics in molybdenite and wolframite from the ran mine initial archean re os ages are still preserved implying that this system in these minerals was more resistant to the overprint a similar retentivity could be shown for the sm nd system in scheelite and powellite associated with the above ore minerals re os isotopic data from the proterozoic mineralization in the kimberley mine point to a recent gain of re most pronouncedly affecting fe rich sulfides such as pyrrhotite a significant re loss in powellitic scheelite an alteration phase of molybdenite bearing scheelite coupled with a marked loss of u in w mo ore minerals complements the observation of a major re uptake in fe sulfides during oxidizing conditions in a weathering environment pyrrhotite under these conditions behaves as an efficient re sink lead isotope signatures from pbsl residues of molybdenite powellite and quartz indicate a continental crustal source and or contamination for the mineralizing fluid by interaction of the fluids with older sedimentary material as represented by the direct host country rocks our investigation reveals the potential of the re os isotopic system applied to crustal hydrothermal ore minerals for genetic tracing and dating purposes the simplified chemical separation of re and os from geological material used in this study together with improvements of chemical yields will enable high precision data to be collected rapidly on crustal material with low os concentrations in the future

microfracturing and fluid mixing in granites w sn ore deposition at vaulry nw french massif central abstract the vaulry w sn mineralisation located at the eastern boundary of the blond rare metal leucogranite is contained in a set of subvertical quartz veins locally with muscovite and minor quartz selvages the sequence of deposition was 1 milky quartz predominantly as fracture filling generally affected by subsequent ductile deformation 2 hyaline quartz wolframite cassiterite 3 minor sulphides other sets of quartz veinlets although generally barren are observed in the blond massif fluid migration at the microscopic scale within the granite and in the vicinity of quartz fractures was constrained by studying the geometry of fluid inclusion planes and fluid inclusion chemistry in and outside the mineralised area three major sets of subvertical fluid inclusion planes are recognised a n050 060 e set mostly developed in the veins and in the immediate vicinity a n110 130 e set regionally developed in the granite and a n140 160 e set of local extent as a whole the density of fip decreases from the mineralised zones toward the barren part of the pluton except for the n140 160 e set these are locally abundant around quartz veinlets with similar orientations that form a broad n s band near the blond locality mineralising fluids observed as primary inclusions in cassiterite and in undeformed hyaline quartz are mostly aqueous with moderate salinity and a minor volatile component at variance with many other w sn deposits in the variscan belt ore deposition occurred around 315 c at an estimated depth of 5 5 km under hydrostatic to slightly suprahydrostatic pressures it resulted from fluid mixing in the central part of a large hydrothermal system between two end members i a hot 425 430 c moderately saline fluid that contained a diluted volatile component and although na dominated minor amounts of li and ca the estimated 18o indicates that this fluid was completely equilibrated with the tectono magmatic pile pseudo metamorphic fluid ii a cold 230 c low salinity fluid evolved meteoric water that mixed with and eventually overprinted the early moderately saline fluid responsible for granite muscovitization at 425 430 c later a second hydrothermal system was initiated by the percolation of heated meteoric water with very low salinity the system was by then at least 3 5 km deep and the fluid was heated to 300 c these characteristics are reminiscent of the ca 305 ma episyenitic hydrothermal system known elsewhere in the n limousin

observations of small scale processes associated with the internal tide encountering an island current meter temperature and microstructure observations of the large amplitude internal tide shoaling on the continental shelf of the east coast of northern new zealand show the complexity of the internal kinematics and mixing the propagation speed of the main internal wave was around 0 3 m s 1 and nonstationary time series analysis was used to locate the trailing short wavelength internal waves in frequency periods of around 40 min and tidal phase space the average energy dissipation rate 5 10 8 m 2 s 3 was an order of magnitude smaller than that observed on the open shelf in other studies but peaks in dissipation rate were measured to be much greater the vertical diffusivity of heat was around 10 4 m 2 s 1 comparable to or greater than other studies examples of the scale and sporadic nature of larger mixing events were observed the behavior was complicated by the nearby steeply shoaling coast of the poor knight islands consistent reflected wave energy was not apparent

dating the giant zhuxi w cu deposit taqian fuchun ore belt in south china using molybdenite re os and muscovite ar ar system abstract the recently discovered zhuxi w cu ore deposit is located within the taqian fuchun ore belt in the southeastern edge of the yangtze block south china its inferred tungsten resources based on new exploration data are more than 280 mt by 2016 at least three paragenetic stages of skarn formation and ore deposition have been recognized prograde skarn stage retrograde stage and hydrothermal sulfide stage secondly greisenization marmorization and hornfels formation are also observed scheelite and chalcopyrite are the dominant metal minerals in the zhuxi deposit and their formation was associated with the emplacement of granite stocks and porphyry dykes intruded into the surrounding carboniferous carbonate sediments huanglong and chuanshan formations and the neoproterozoic slate and phyllites the scheelite was mostly precipitated during the retrograde stage whereas the chalcopyrite was widely precipitated during the hydrothermal sulfide stage a muscovite 40ar 39ar plateau age of about 150 ma is interpreted as the time of tungsten mineralization and molybdenite re os model ages ranging from 145 9 2 0 ma to 148 7 2 2 ma for the subsequent hydrothermal sulfide stage of activity as the time of the copper mineralization our new molybdenite re os and muscovite 40ar 39ar dating results along with previous zircon u pb age data indicate that the hydrothermal activity from the retrograde stage to the last hydrothermal sulfide stage lasted up to 5 myr from 150 6 1 5 to 145 9 1 ma and is approximately coeval or slightly later than the emplacement of the associated granite porphyry and biotite granite the new ages reported here confirm that the zhuxi tungsten deposit represents one of the mesozoic magmatic hydrothermal mineralization events that took place in south china in a setting of lithospheric extension during the late jurassic 160 150 ma it is suggested that mantle material played a role in producing the zhuxi w cu mineralization and associated magmatism

mobility of early islanders in the philippines during the terminal pleistocene early holocene boundary pxrf analysis of obsidian artefacts abstract the philippine archipelago spans over two distinct biogeographic zones sundaland and wallacea we report in this paper on finds from ilin island just off the coast of sw mindoro and el nido in northern palawan while the island of palawan is linked to sundaland mindoro and ilin island belong to wallacea east of huxley s line ongoing archaeological investigations at bubog 1 rockshelter on ilin island and ille cave rockshelter in northern palawan delivered obsidian artefacts found in terminal pleistocene and early holocene layers pxrf analysis of the obsidian samples from mindoro and palawan shows that they were coming from the same yet unknown source they clearly indicate that the two distinct paleogeographical regions were linked to each other suggesting human interaction and maritime networks as early as ca 12ka bp the results of this study contribute substantially to our understanding of the mobility of early islanders during the terminal pleistocene and the processes of human island adaptation and enhance our current knowledge of subsistence strategies across the region

geochronology and geochemistry of granitoids related to the giant dahutang tungsten deposit middle yangtze river region china implications for petrogenesis geodynamic setting and mineralization abstract porphyry and skarn deposits in the middle yangtze valley within the northern yangtze craton have a combined tungsten resource of 3 million tonnes mt and represent one of the most important tungsten regions in the world the dahutang porphyry tungsten deposit with reserves of 1 mt is one of the largest deposits uranium pb analyses for the ore related granitoids yield ages of 147 4 0 58 ma 148 3 1 9 ma for porphyritic biotite granite 144 7 0 47 ma 146 1 0 64 ma for fine grained granite and 143 0 0 76 ma 143 1 1 2 ma for granite porphyry a progressive youngling of ages that is consistent with field observations geochemical data show that the three types of granite are characterized by enrichments in rb pb and u and depletion in ba nb p and ti with asi molar al 2 o 3 cao na 2 o k 2 o 1 1 that is characteristic of a peraluminous melt the p 2 o 5 contents of the granites are 0 13 0 37 and have a positive correlation with sio 2 and they are thus s type intrusions they exhibit initial 87 sr 86 sr of 0 721 to 0 731 and e nd t of 5 06 to 7 99 for porphyritic biotite granite 0 7196 to 0 7289 and 6 29 to 6 74 for fine grained granite and 0 7153 to 0 7365 and 5 09 to 7 64 for granite porphyry chondrite normalized rare earth element ree patterns for the granites are characterized by enrichment in the light ree and a strong negative eu anomaly indicating that they were derived from the proterozoic pelitic and psammitic basement strata and experienced strong fractional crystallization of plagioclase our ca 150 140 ma age for the dahutang s type magmatism and w mineralization is identical to that of the i type magmatism related to cu au mo fe bearing porphyry and skarn deposits along the middle to lower yangtze river valley we propose that the latest jurassic to earliest cretaceous granitoids and ores formed during a tearing of the subducting izanagi slab which caused the upwelling of asthenosphere and resulting mantle crust interaction the s type granitoids and related w ore systems resulted from the re melting of the proterozoic crust whereas the i type granitic rocks and related ores are attributed to the partial melting of the subducted slab

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

trace elements and sr nd isotopes of scheelite implications for the w cu mo polymetallic mineralization of the shimensi deposit south china the shimensi deposit south china is a newly discovered w cu mo polymetallic deposit with a reserve of 0 76 million tones wo 3 one of the largest tungsten deposits in the world we report elemental and sr nd isotopic data for scheelites from the giant deposit to determine the source region and genesis of the deposit scheelite is the most important ore mineral in the shimensi deposit trace elements including rees and nd sr isotopic compositions of scheelites were used to constrain the origin of the mineralizing fluids and metals our data reveal that the rees of scheelite are mainly controlled by the substitution mechanism 3ca 2 2ree 3 ca where ca is a ca site vacancy scheelites from the shimensi deposit show negative eu anomalies in some samples but positive eu anomalies in others in the chondrite normalized ree patterns the variation of eu anomalies recorded the ore forming processes considering the close spatial and temporal relationship between the mineralization and porphyritic granite we think the negative eu anomalies were inherited from the porphyritic granite and the positive ones from destruction of plagioclase of country rock during fluid rock interaction the variation of cathodeluminescence cl color of a single scheelite from red to blue and to yellow was likely associated with the increase of ree contents the scheelites hosted in the mesozoic porphyritic granite with negative eu anomalies formed in a primitive ore forming fluid whereas the scheelites hosted in neoproterozoic granite with positive eu anomalies precipitated in an evolved ore forming fluid the high nb ta lree contents and lree enriched ree patterns of scheelites from the shimensi deposit reveal a close relationship with magmatic hydrothermal fluids the scheelites from the shimensi deposit are characterized by low e nd t values 6 1 8 1 and unusually high and varied initial 87 sr 86 sr ratios 0 7230 0 7657 the e nd t values of scheelites are consistent with those of the mesozoic porphyritic granite but the sr isotopic ratios are significantly higher than those of the granites and importantly beyond the sr isotopic range of normal granites this suggests that the ore forming fluids and metals cannot be attributed to the mesozoic porphyritic granites alone the local neoproterozoic shuangqiaoshan group schists gneisses with high rb sr ratios and thus radiogenic sr isotopic compositions should have contributed to the ore forming fluids and metals particularly in a later stage of ore forming process by intense fluid rock interaction this is different from a commonly accepted model that the ore forming fluids and metals were exsolved exclusively from the granite plutons

on the sources and uses of obsidian during the paleolithic and mesolithic in poland abstract eighty six obsidian artifacts from twenty paleolithic and mesolithic archaeological sites in poland were analyzed using non destructive energy dispersive x ray fluorescence edxrf analysis and assigned to parent geological obsidian source chemical type results of the study the first country wide survey of its kind support the conclusion that the geological source of obsidian remained largely unchanged for thousands of years that obsidian use appears to have been minimal throughout the paleolithic and mesolithic regardless of distance to source that obsidian artifacts were used to perform the same functions as their non obsidian flint and radiolarite counterparts and that the distinct visual properties of volcanic glass may have contributed to its recognition as unique and exotic in different social contexts

in situ trace elements and sr isotopes in scheelite and s pb isotopes in sulfides from the shiweidong w cu deposit giant dahutang ore field implications to the fluid evolution and ore genesis abstract the shiweidong w cu polymetallic deposit with resources of 300 000 t wo3 and 200 000 t cu is one of the major tungsten polymetallic deposits in the giant dahutang ore field this study conducted a series of in situ analyses on scheelite and sulfides aiming to provide some new insights into the sources hydrothermal ore forming processes fluid evolution history and genesis of this deposit which is of importance to understand the formation of the super large dahutang ore field quartz vein and veinlet disseminated type tungsten ore bodies are mainly hosted in neoproterozoic granodiorite and or the yanshanian porphyritic two mica granites four stages of mineralization from early to late are identified in this deposit 1 pegmatite stage 2 silicate oxide stage 3 oxide sulfide stage and 4 sulfide stage the 34sv cdt values of stage 3 chalcopyrite and pyrite are from 1 73 to 1 46 and from 1 66 to 0 31 respectively indicating a magma related hydrothermal origin the 206pb 204pb 2067pb 204pb and 208pb 204pb ratios of pyrite range from 18 169 to 18 295 15 650 to 15 679 and 38 496 to 38 525 respectively revealing a crust origin for the pb trace element compositions of scheelite show that the both stage 2 scheelite scheelite ii and stage 3 scheelite scheelite iii have high contents of nb and rees the scheelite ii has a narrow range of the y ho ratios 16 2 31 0 obviously negative eu anomalies eu eu 0 04 0 46 and relatively low 87sr 86sr ratios of 0 72640 0 73336 whereas scheelite iii shows variable y ho ratios of 20 6 96 9 positive eu anomalies eu eu 1 31 7 11 and relatively high 87sr 86sr ratios of 0 73496 0 76098 these data indicated that the eu anomalies and sr isotopic compositions of scheelite ii were inherited from magmatic hydrothermal fluids whereas those of scheelite iii were sourced from modified fluids due to intense fluid rock interaction and input of meteoric fluids our data also reveal that the rees of scheelite ii and scheelite iii are mainly controlled by the substitution mechanism of 3ca2 ca 2ree3 the w rich reduced fluids and intense fluid rock interactions which could provide enough w and ca are likely the key factors for the formation of scheelite in the shiweidong tungsten deposit

sm nd and rb sr isotope systematics of scheelites possible implications for the age and genesis of vein hosted gold deposits a positive correlation between present day sup 143 nd sup 144 nd and sup 147 sm sup 144 nd ratios from scheelite samples from the hollinger mcintyre coniaurum gold deposit of ontario canada corresponds to an age of 2403 plus minus 47 ma and may date the age of gold mineralization initial isotope ratios of scheelites suggest that the fluid responsible for the scheelite and gold mineralization was probably of mantle origin and that it subsequently interacted with continental crust

are obsidian subsources meaningful units of analysis temporal and spatial patterning of subsources in the coso volcanic field southeastern california archaeologists frequently assign artifacts to chemically discrete subsignatures of major obsidian sources while the technical ability to do so has been demonstrated it remains to be shown that such information is behaviorally meaningful indeed some analysts choose not to make such determinations under the presumption that the data are not anthropologically relevant using a case study from the coso volcanic field which has at least four distinct subsignatures we examine this problem and conclude that subsource identification can be useful and quite interesting this is particularly so when large datasets encompassing spatially expansive areas can be assembled and statistically analyzed

multiple origins of bondi cave and ortvale klde nw georgia obsidians and human mobility in transcaucasia during the middle and upper palaeolithic abstract using pixe four types of elemental compositions were found among obsidian artefacts from the bondi cave and ortvale klde middle to upper palaeolithic sites in nw georgia one of those types corresponds to obsidians from the chikiani source whose compositions were determined with a very good agreement by pixe and icp aes ms the composition of chikiani obsidians is remarkably constant despite k ar and 39ar 40ar extrusion ages from ca 2 4 and 2 8 ma the compositions of two other groups of obsidian artefacts are similar to source materials from eastern anatolia and armenia in particular ikisdere sarikamis gutansar and hatis obsidian is only a minority component in the lithic assemblages at the bondi cave and ortvale klde both neanderthal and modern human populations used obsidian in particular from chikiani considering that the shortest walking distance to this nearest source is at minimum of about 180 km and to other potential sources of more than 350 km it is suggested that this material reached these two sites mostly if not exclusively by a series of down the line exchanges

sm nd and ree characteristics of tourmaline and scheelite from the bjorkdal gold deposit northern sweden evidence of an intrusion related gold deposit the bjorkdal quartz vein hosted gold deposit is located 25 km northwest of skellefte in northern sweden within a paleoproterozoic volcanosedimentary sequence at the margin of a quartz monzodiorite granitoid northeast trending 030 050 quartz veins from the eastern open pit within the bjorkdal deposit contain quartz scheelite tourmaline calcite and sulfides with visible gold vein quartz shows undulatory extinction and sutured margins or is polycrystalline in form features which suggest postcrystallization deformation coarse scheelite crystals 5 mm within the quartz veins are crosscut by thin veins of quartz calcite sulfides and gold the calcite in these crosscutting fractures is variably replaced by biotite or actinolite tourmaline from the quartz veins has low total ree contents 1 chondrite and lree enriched patterns la sm n 2 8 4 5 la yb n 1 8 5 1 with strong positive eu anomalies eu eu 3 9 17 4 in contrast the scheelite has a bell shaped ree pattern enriched in mree but also with positive eu anomalies eu eu 1 4 2 4 the ree pattern of scheelite results from a strong crystallographic effect largely due to the size of the ca site and charge balance sm nd dating of scheelite from the bjorkdal ore yields an age of 1893 34 ma which coincides with a previously suggested age of the host intrusion the end values of the scheelite 1 8 and 87sr 86sr initial ratios of the tourmaline 0 7013 0 7014 are also consistent with derivation of ree and sr in these minerals from the jorn granitoids overall the petrographic geochemical and isotopic data strongly suggest that bjorkdal is an intrusion related gold deposit and that there is no requirement for involvement of external post magmatic hydrothermal fluids

simulations of internal solitary wave interactions with mesoscale eddies in the northeastern south china sea abstractwith the combined analysis of synthetic aperture radar image and satellite altimeter data collected in the northeastern south china sea scs this study found one type of distorted phenomenon of internal solitary wave isw with the long front caused by the oceanic mesoscale eddy motivated by these satellite observations the authors carried out numerical experiments using the fully nonhydrostatic and nonlinear mitgcm to investigate the perturbation of isws by an isolated cyclonic or anticyclonic eddy the results show that the isw front is distorted by these oceanic eddies due to the retardation and acceleration effects at their two sides the isw energy along the front is focused onto scattered from the wave fragment where a concave convex pattern is formed and the previously accumulated energy in the focusing region is gradually released after the isw propagates away from the eddies the isw amplitude is modulated greatly by the eddies due to the energy redistribution along the front se

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

ore genesis of the zhuxi supergiant w cu skarn polymetallic deposit south china evidence from scheelite geochemistry abstract scheelite is the main ore mineral in skarn type tungsten deposits which can be used to track the ore forming processes and sources the zhuxi w cu deposit 3 44 mt wo3 at 0 54 and 0 10 mt cu at 0 57 located in the northern part of the jiangnan orogen is one of the largest tungsten deposits in the world skarn and orebodies occur mainly within the contact zone between the mesozoic highly fractionated intrusions and carboniferous carbonate sediments huanglong and chuanshan formations our data reveal that the rees of scheelite are mainly controlled by the substitution mechanism 3ca2 2ree3 ca scheelites from the zhuxi deposit show negative eu anomalies in the prograde skarn stage but positive eu anomalies in the retrograde skarn stage in the chondrite normalized ree patterns variation of eu anomalies recorded the ore forming processes the negative eu anomalies were inherited from the mesozoic granites and the positive ones formed under more reduced redox conditions the decrease of mo concentrations along with increase of eu and ce of scheelite from prograde to retrograde skarn stage support a temporal decrease in oxygen fugacity of the mineralization fluids the scheelites from the zhuxi deposit are characterized by low end t values 10 1 to 7 0 and high initial 87sr 86sr ratios 0 71231 0 72371 which are different from the scheelites hosted in vein type au w deposits contributed mainly by mantle the nd sr isotopes of scheelites are consistent with the results of the three mesozoic granites indicating their genetic relationship however the scheelites show variable nb ta compositions which straddle between the values of mesozoic granites and the country rock of shuangqiaoshan group meta sedimentary rocks indicating the shuangqiaoshan group also has contributed to mineralization this is different from a commonly accepted model that the ore forming fluids and metals were exsolved exclusively from the granite plutons

the sulu sea internal soliton experiment abstract we present the results of a comprehensive study of large amplitude internal solitons generated in the sulu sea in the philippines by intense tidal flow over a sharp bathymetric feature surface signatures of these waves have been observed in images from the dmsp landsat and nimbus 7 satellites and the space shuttle sir a synthetic aperture radar a two week experiment was conducted in the sulu sea in may 1980 from r v oceanograher during which a three mooring phased array of current meters and thermistors was implanted near the wave source and at 82 km and 200 km from the source seventeen soliton packets were observed whose properties underwent significant change as they propagated across the sea vertical profiles of density temperature and acoustic backscatter as well as radar and photographic surface signatures were obtained from the ship data from satellites moorings and the ship give unprecedented information on the spatial and temporal characteristics of solitary waves which ha