ree composition of an aqueous magmatic fluid a fluid inclusion study from the capitan pluton new mexico u s a abstract the ree content of aqueous magmatic derived fluids trapped in fluid inclusions has been determined by icp ms after crush leach extraction of the fluids in 4 samples the total ree concentration varies between 200 and 1300 ppm and is dominated by the lree especially la ce and nd fluids were released at different times from a melt which changed composition as it underwent fractional crystallisation and this is reflected in the concentration of ree in solution early formed quartz fluorite veins hosted by granophyre contain the highest concentration of ree and appear to be in equilibrium with aplite melt from which the fluid was inferred to have been derived since calculated fluid melt distribution coefficients are in broad agreement with experimentally derived values variation in the ree content of the fluids is independent of salinity which remains constant at 80 wt total salts later veins hosted by aplite contain fluid derived from a porphyritic melt and have lower ree concentrations reflecting the greater incorporation of ree into mineral phases crystallising from the melt titanite and allanite occur in these later veins ree mineral fluid distribution coefficients have been calculated for these minerals and show there is a strong preference for ree to partition into the minerals

chronological discord between the last interglacial paleosol s1 and its parent material in the chinese loess plateau abstract an and porter geology 25 1997 603 reported six high dust influx events of millennial timescales recovered from the last interglacial paleosol s1 and correlated them to six cool events of millennial timescale in the north atlantic however the complexity of soil forming processes may have made the chronological correlation with the north atlantic records inadequate to examine the complexity of the s1 formation the s1 paleosol was traced laterally and identified based on the preserved characteristics observed in the field and analyzed in the laboratory our data show that from the northwest to the southeast the s1 paleosol gradually converges from three distinctive soil profiles into a single welded profile because the net rate of loess accumulation was attenuated to the southeast and pedogenic development intensified southeastward during the last interglacial three soil forming events within the s1 paleosol s1s1 s1s2 and s1s3 separated by two loess units s1l1 and s1l2 in the northwestern part of the loess plateau are stratigraphically coeval with a single soil profile in the southeastern margin of the loess plateau in the southeast the s1 paleosol developed into underlying older loess l2 e g at the lantian section the three paleosols s1s1 s1s2 and s1s3 are partially welded in the central part of the chinese loess plateau e g at the tianshui section where the lower portion of s1 paleosol developed in the underlying older loess unit l2 in the northwestern margin of the chinese loess plateau e g at the lanzhou section the preservation of the repeating soil loess sequence s1s1 s1l1 s1s2 s1l2 and s1s3 continuously documented the climatic events of the last interglacial our data also show that the magnetic signatures and particle size information are more or less acceptable climatic proxies only for the northwestern sections where the degree of pedogenesis was lower and the rate of eolian influx was greater during the last interglacial it appears that in all cases investigated the median grain size and the coarse fraction 63 m content define the upper and lower boundaries of the s1 paleosol reasonably well and can be used to estimate the time transgressive nature of the s1 paleosol relative to its parent material soil welding bioturbation and material translocation within the s1 soil profiles make it impossible to preserve the detailed and high resolution information of climate changes in those s1 profiles in the southeastern part including the popularly called central part of the chinese loess plateau

stratigraphic evidence for multiple holocene advances of lillooet glacier southern coast mountains british columbia holocene lateral moraines in the coast mountains of british columbia are commonly composed of multiple drift units related to several glacier advances in this paper we document lateral moraine stratigraphy at lillooet glacier in the southern coast mountains five tills separated by laterally extensive paleosols and layers of large woody debris were found in three cross sectional exposures through the northeast lateral moraine and two shallow gullies incised into its steep proximal face eighteen new radiocarbon ages constrain the timing of five separate advances of lillooet glacier 1 prior to 3000 14 c years bp 2 3000 14 c years bp 3 2500 14 c years bp 4 1700 to 1400 14 c years bp and 5 during the little ice age lia after 470 14 c years bp the lillooet glacier chronology is broadly synchronous with other glacier records from the coast mountains these records collectively demonstrate climate variability at higher frequencies during the late holocene than is apparent from many paleoecological reconstructions reconstructions of glacier fluctuations are often hampered by poor preservation of landforms that predate the extensive lia advances of the latest holocene our results highlight the potential of lateral moraine stratigraphy for reconstructing these earlier events

geochemistry of a silicified felsic volcaniclastic suite from the early archaean panorama formation pilbara block western australia an evaluation of depositional and post depositional processes with special emphasis on the rare earth elements abstract many elements in a suite of pervasively silicified dacitic volcaniclastic and volcanic rocks from the early archaean panorama formation warrawoona group western australia were strongly depleted or enriched relative to those in equivalent unaltered units during widespread post depositional metasomatism the present compositions of the altered rocks are dominated by al 2 o 3 k 2 o and sio 2 and lie on or close to a quartz sericite mixing line the al contents were probably inherited from the original dacitic rocks while si some k and possibly rb may have been introduced during metasomatism the elements mg ca na and to a lesser extent fe mn and sr have been depleted relative to al during alteration whereas silica has been greatly enriched the high and variable ba concentrations suggest that ba like si was introduced during silicification the ree and th were relatively immobile during alteration and were diluted during silicification in the same proportion as al most of the rocks represent detrital sand and silt sized felsic tephra debris eroded from felsic volcanic rocks or ash fall deposits that underwent a short interval of transport and deposition dominated by physical rather than chemical processes a few siltstones contain clay minerals that probably formed by the chemical weathering of warrawoona group basalts the siltstones have lower th and la concentrations lower la lu ratios and higher sc and cr concentrations than felsic rocks in the suite regional alteration pervasively silicified the original sediments shortly after deposition the replacement mineral assemblage indicates a maximum temperature for hydrothermal alteration of about 350 c because of the lack of chemical weathering and the low temperature of post depositional alteration ree abundances in volcaniclastic rocks of the panorama formation reflect their felsic volcanic provenance and are interpreted to have preserved a relict magmatic signature the lack of a negative eu anomaly and high la lu ratio chondrite normalized ratio is 7 to 39 suggest that magmas of the panorama formation formed by direct melting of an eclogite residue without subsequent crystallization of feldspar during the commencement of cratonization of the pilbara block this origin differs from the origin of some other silicic volcanic rocks of the duffer formation representing earlier felsic volcanic activity of the warrawoona group that were produced by fractional crystallization from basaltic parents this suggests a polygenetic origin for felsic magmas of the warrawoona group

geological and geochemical characteristics in the paleo weathering crust sedimentary type ree deposits western guizhou china abstract a supergene ree deposit closely interrelated with the weathering of the emeishan basalt formation was produced in the xuanwei formation the overlying stratum of the late permian emeishan basalt formation in west guizhou china the host strata consist primarily of offwhite kaolinite clay rock and or grayish black carbonaceous shale mineralogical analyses reveal that kaolinites are the major minerals in ree ores with small amounts of smectite illite boehmite hornblende pyrophyllite calcite dolomite and or iron bearing minerals with a certain proportion of feldspar quartz crystal debris and noncrystal debris geochemical analyses reveal high enrichment of trace elements like cu nb ta zr and hf the host strata feature considerable lithological variability close interrelation of the ree grade with the lithology and uneven spatial distribution of the ree ores which are mostly found in lufang maojiaping and zhangsigou profiles of weining county and can be as thick as 20 m of the five stratigraphic profiles 48 have their whole rock ree higher than 1000 ppm the ree in this framework consists primarily of ion adsorbed phases and ree rich residual independent mineral phases comprehensive analyses suggest that the source may not only include the emeishan basalt but the intermediate acid volcanic rocks evolved from the emeishan basalt in the later periods the hydrothermal alteration subsequently imposed on the host strata might have boosted the mineralization of the rare earth the preliminary genetic model should have been the denudation product from the weathering of the parent rock was migrated to the sea continental margin at the continent side carrying huge quantities of ree with it and was preserved by the quick marine transgression the host strata consist primarily of kaolinite clay rock and or carbonaceous shale which are so far believed to be a sedimentary type ree deposit closely interrelated with weathering effect

rare earth element geochemistry of clastic and chemical metasedimentary rocks associated with hydrothermal sulphide mineralisation in the olary block south australia abstract analysis of a variety of rock types from the south australian portion of the lower to middle proterozoic willyama inliers by icp ms demonstrate that primary rare earth element ree distributions remained essentially unchanged despite multiphase deformation and amphibolite grade metamorphism variable trends of preferential ree mobilisation are observed only where large amounts of fluid caused the rock to undergo strong retrogression and or hydrothermal alteration except for these conditions ree can be considered immobile and their distribution is generally independent of mineralogy thus providing a powerful tool for the characterisation of provenance of protoliths in a high grade metamorphic terrain ree signatures and other geochemical constraints of some volcanogenic sediments for example point to an andesitic parentage suggesting bimodal and gradually changing volcanism occurring in a developing intracontinental rift zone ree distributions in metasediments associated with sulphide mineralisation reflect both physico chemical characteristics of the ore bearing fluids and rock compositions comparison of their ree profiles allows discrimination between a strata bound redox controlled deposits b exhalative mineralisation and c epigenetic vein type mineralisation ree distributions in the analysed rocks are in agreement with other lines of textural and geochemical evidence for that limited syn tectonic remobilisation low fluid rock ratios unchanged primary ree signatures but widespread late stage mobilisation of sulphides high fluid rock ratios selective mobilisation of ree occurred in the olary block ree signatures of exhalative precipitates associated with sulphide mineralisation do not show a systematic stratigraphic variation but are indicative of fluctuating f o 2 conditions over short distances and display only moderately positive eu anomalies this contrasts with findings for the adjacent broken hill block and highlights the dissimilarities of ore formation processes that were active in the olary and the broken hill block as well as the depositional differences between the two blocks

rare earth element and heavy metal behaviour associated with the epithermal gold deposit on lihir island papua new guinea a thick sequence of alkaline intrusions and volcanic rocks underlies a quaternary caldera on lihir island the sequence is host to a still active subaerial hydrothermal system and associated epithermal gold mineralization chondrite normalized la lu cn and la sm cn ratios progressively increase up the alteration sequence from the potassic alteration zone to the argillic zone to the advanced argillic zone tb lu cn ratios only significantly increase in argillic and advanced argillic assemblages surface oxide alteration lithologies and acid sulphate water precipitates possess distinctly lower la lu cn and tb lu cn ratios than the underlying subsurface alteration units the changes in the ree lree and hree fractionation trends from subsurface to surface alteration zones reflect the transition from a magmatic hydrothermal neutral chloride fluid regime at depth to acid sulphate meteoric waters in the upper portion of the alteration profile boiling of the lree eu enriched magmatic fluids occurred at a depth of at least 750 m it is proposed that pronounced differential flow rates of the vapour and liquid phases and solution chemistry changes approximately above 300 350 m caused the incorporation of lree and eu into anhydrite calcite veins and the deposition of lree and hree into wallrocks of upper parts of the potassic alteration unit condensation of the vapour phases into meteoric waters gave rise to low temperature acid fluids that deposited large amounts of lree within argillic and advanced argillic alteration units this was also accompanied by hree mobility due to large fluid volumes acid fluid conditions and abundant sulphate complexes within the solutions the hree were either lost from the hydrothermal system or deposited in oxide assemblages and acid sulphate water precipitates

behaviour of rare earth elements during hydrothermal alteration at the buena esperanza copper silver deposit northern chile abstract a study of the ree behaviour in alteration zones of the buena esperanza subvolcanic cu ag deposit located in the coastal range of northern chile reveals that the elements are mobile in the rocks during alteration the ore forming process developed in three different stages of alteration mineralization the hydrothermal alteration of the early and middle stages affected basaltic fragments of a breccia pipe la and ce were leached from the rock fragments located at the bottom and at the middle part of the breccia pipe and partly redeposited at the top during alteration sm eu and tb were released selectively and the heavy ree behaved as relatively immobile elements sericite is the most important alteration mineral for fixing the ree during this stage the incoming fluids had low ree contents the late stage of hydrothermal alteration happened simultaneously with the intrusion of a gabbroic volcanic neck affecting mainly these subvolcanic rocks ree patterns of samples from the top and bottom of the alteration zone exhibit roughly parallel trends but are systematically enriched in ree in comparison to unaltered samples this enrichment seems to be more intensive at the top of the altered area coinciding with the enrichment of rb k and cu in these rocks epidote plays the most important role for fixing this hydrothermal input of ree during the latest stage of alteration

clay mineral regions in peoria loess mississippi river basin four distinct clay mineral provinces are identified in peoria loess in the mississippi river basin upper ohio wabash illinois upper mississippi missouri and lower mississippi the kaolinite illite expandable mineral compositions and the vermiculite montmorillonite compositions differ distinctly in these depositional provinces the upper mississippi missouri province 60 of the area of the mississippi river basin is the dominant source region for clay minerals in the peoria loess along the lower mississippi valley

upstream control of river anastomosis by sediment overloading upper columbia river british columbia canada anastomosing rivers systems of multiple interconnected channels that enclose floodbasins constitute a major category of rivers for which various sedimentary facies models have been developed while the sedimentary products of anastomosing rivers are relatively well known their genesis is still debated a rapidly growing number of ancient alluvial successions being interpreted as of anastomosing river origin including important hydrocarbon reservoirs urge the development of robust models for the genesis of anastomosis to facilitate better interpretation of ancient depositional settings and controls the upper columbia river british columbia canada is the most studied anastomosing river and has played a key role in the development of an anastomosing river facies model two hypotheses for the origin of upper columbia river anastomosis include the following i downstream control by aggrading cross valley alluvial fans and ii upstream control by excessive bedload input from tributaries both upstream and downstream control may force aggradation and avulsions in the upper columbia river in order to test both hypotheses long term millennia scale floodplain sedimentation rates and avulsion frequencies are calculated using 14c dated deeply buried organic floodplain material from cross valley borehole transects the results indicate a downstream decrease in floodplain sedimentation rate and avulsion frequency along the anastomosed reach which is consistent with dominant upstream control by sediment overloading the data here link recent avulsion activity to increased sediment supply during the little ice age ca 1100 to 1950 ad this link is supported by data showing that sediment supply to the upper columbia study reach fluctuated in response to holocene glacial advances and retreats in the hinterland upstream control of anastomosis has considerable implications for the reconstruction of the setting of interpreted ancient anastomosing systems the present research underscores that anastomosing systems typically occur in relatively proximal settings with abundant sediment supplied to low gradient floodplains a situation commonly found in intermontane and foreland basins

mineralogy and geochemical behavior of trace elements of hydrothermal alteration types in the volcanogenic massive sulfide deposits ne turkey abstract volcanogenic massive sulfide vms deposits of the eastern pontides turkey are hosted by the maastrichtian eocene dacite and rhyodacite series accompanied by lesser andesite and basalts as well as their pyroclastic equivalents with tholeiitic to calc alkaline affinity the ore mineral assemblages are chalcopyrite sphalerite galena chalcocite covellite bornite and tetrahedrite potassic phyllitic sericitic argillic kaolinitic and smectitic silicic propylitic and hematitic alteration is commonly associated with these deposits hfse lile trte and ree contents show strong variability in different alteration types resulting from interaction with acid or alkaline fluids sample groups showed chondrite normalized enrichment of lree relative to hree and sub parallel trends except for the hematitic and phyllitic alteration types mree are strongly depleted in the zones of most intense silicification and kaolinization most sample groups have strongly to slightly negative eu anomalies ranging from 0 35 to 0 88 mean hematitic 1 45 and propylitic altered rocks 1 11 have slightly to moderately positive anomalies the negative eu anomalies indicate the low temperatures of fluids 200 c no ce anomaly was observed except for phyllitic alteration where a slight positive anomaly was noted the chondrite normalized trace and ree patterns of the altered rocks are similar to each other suggesting that they were derived from a common felsic source the alteration groups formed from acid intermediate and alkaline hydrothermal solutions some transition base and precious metals and volatile elements were clearly enriched especially in the hematitic silicic kaolinitic and phyllitic altered samples the other elements exhibit different behaviors in different sample groups ree behavior is relatively immobile in the silicic hematitic kaolinitic and partially in moderately and propylitic altered rocks based on mass balance calculations lile and hfse appear mobile in the altered sample groups except in the propylitic altered rocks trte behave as relatively immobile in most of samples except in some of the silicic and phyllitic altered rocks and especially in the hematitic altered samples hfse most of the transition w mo cu and sb and some other trace elements pb as hg bi se and tl are enriched in the hematitic altered samples and in the some silicic altered samples the highest as bi mo se and hg concentrations in the hematite altered samples can be used to distinguish other alteration types and may be a useful indicator in a prospect scale base metal exploration

behavior of the rare earth elements and other trace elements during interactions between acidic hydrothermal solutions and silicic volcanic rocks southwestern japan abstract rare earth elements and other trace elements in some roseki deposits mostly pyrophyllite and sericite silicastones alunites and related rocks were determined in order to examine behavior of the trace elements in the acidic hydrothermal alteration of silicic volcanic rocks the analyzed concentrations were normalized to the probable unaltered original rock values inferred from the averaged data of some silicic volcanic rocks the trace element characteristics for those materials are as follows 1 most of the elements such as na fe ba and light ree were leached from the silicastones while heavy ree th hf and zr were retained in them 2 alunite samples have light ree enriched and heavy ree depleted features 3 the typical roseki deposits are characterized by middle ree depletions and have v shaped ree patterns on the normalized concentrations vs atomic number diagram such characteristic patterns of the roseki deposits can be explained by superimposition of the light ree enriched and heavy ree enriched materials such as alunite and silica it is important that trace element behaviors are highly selective and some elements e g yb lu hf and zr were strongly retained in the rocks even under strongly acidic hydrothermal processes

relative elemental mobility during hydrothermal alteration of a basic sill isle of skye n w scotland in sconser quarry isle of skye a thin tertiary basic sill is cut by vertical veins which formed fluid conduits in a major meteoric hydrothermal system in order to study the relative mobility of different elements during hydrothermal metamorphism sill material adjacent to a large 6 mm wide vein was cut into slices and subjected to geochemical and isotopic analysis

low sulfidation type au ag mineralization at bergama izmir turkey abstract bergama the center of bergama county is located in western turkey and includes the villages of ovacik narlica and saganci the ovacik epithermal gold silver deposit is located in the western anatolian volcanic and extensional province adjacent to the ene trending bergama graben some 100 km north of the city of izmir gold of economic grades at the ovacik deposit reserves 4 19 mt at 7 6 g t occurs in epithermal quartz veins which display low temperature epithermal textures including crustiform banding quartz pseudomorphs after bladed calcite and multiphase hydrothermal breccias alteration minerals at both ovacik and narlica are dominated by smectite mixed layer illite smectite chalcedonic quartz and adularia whereas major kaolinite and minor mixed layer smectite illite 13 4 a occur at saganci the total sulfide content at ovacik is low geochemical variations in altered wall rocks at ovacik and narlica are generally characterized by two fold enrichments in k rb cs and 25 to 93 depletions in sr ca mg na and even higher depletions 96 to 99 decrease in the quartz adularia vein zone lanthanum ce pr hf zr sm eu gd tb and ho also exhibit up to 50 depletions in the wall rock and even more so up to 90 depletion for la and nd in the vein structure wall rock enrichment in au ag as hg and sc is by factors of 60 150 88 8 and 3 respectively the ranges of ree in both the altered volcanic rocks and quartz adularia veins are wide and may reflect either significant mobilization of ree during alteration and mineralization or their dilution by the metasomatic processes from fresh volcanic rocks through montmorillonite illite adularia altered wallrock to quartz adularia veins high rb sr ratios in adularia illite altered areas are closely related to the presence of k rich alteration minerals low rb sr ratios and corresponding low k values at saganci are due to acid leaching of volcanic rocks positive correlation coefficients between au and ag pb zn cd cu and sb in epithermal quartz veins all of which are 0 51 are significant silver and sb are remarkably enriched at higher levels of the deposit no correlation occurs between au and as or ag and as the ovacik quartz in au ag bearing veins has 18o values ranging from 9 5 to 15 7 whereas d values of fluid inclusions in quartz range from 89 to 125 however the narlica quartz in au ag bearing veins returned 18o values ranging from 5 9 to 8 3 whereas the d values of fluid inclusion in quartz range from 82 to 99 18o results indicate that ore forming hydrothermal fluids at ovacik and narlica had 18oh2o values ranging from 2 9 to 3 5 average 0 24 and from 2 96 to 0 6 average 1 6 respectively they are thus 18o enriched in comparison with present day meteoric and hydrothermal meteoric waters 5 4 18o 18oh2o and d values suggest that mineralizing solutions were a mixture of meteoric and magmatic waters the 34s sulfide data at ovacik and narlica range from 2 1 to 5 3 average 1 7 and from 4 6 to 2 7 average 0 36 respectively these 34s sulfide values are consistent with a magmatic source for s

rare earth element distribution in exhalites associated with broken hill type mineralisation at the pinnacles deposit new south wales australia abstract rare earth element ree concentrations in exhalites and pelites associated with strata bound base metal broken hill type mineralisation have been measured for the early proterozoic pinnacles deposit in western new south wales garnetites garnet rich rocks and sulphide rich garnet gahnite bearing rocks exhibit a wide variety of ree concentrations particularly lree and eu which cannot be related entirely to changes in mineralogy but show some correlation with stratigraphic position relative to the main orebody exhalites lying in the footwall to the mineralised rocks have negative eu anomalies and steep lree enriched patterns whereas exhalites in the hanging wall to the ores and silicate rich rocks from within the ore lenses have zero or positive eu anomalies and less lree enriched patterns hree have more consistent values throughout the deposit but in places are strongly depleted non mineralised pelites are slightly enriched in the ree relative to shale composite values and have negative eu anomalies it is argued in this paper that because the variations in data can be related to the stratigraphic location of samples relative to the orebodies that the observed ree distributions are due to fluctuations in ree concentrations in the primary exhalative fluids rather than differential mobilisation of ree during a second post depositional episode of hydrothermal alteration or mobilisation of the ree during prograde granulite facies metamorphism or retrograde amphibolite facies metamorphism which has affected the area the lack of association between metamorphic mineral assemblages and ree distribution and the absence of any homogenisation of the ree concentrations suggest that the data reflect the primary exhalative fluid composition and that the variations in ree data reflect changes in palaeoenvironmental conditions such as f o 2 and temperature a corollary to this conclusion is that there was minimal mobilisation of the ree during subsequent metamorphism

late quaternary climate change loess sedimentation and soil profile development in the central great plains a pedosedimentary model research on soil genesis often assumes a top down model in which the soil profi le develops downward from a stable land surface this model is inapplicable to upland landscapes affected by frequent dust deposition where soils grow upward as they develop on the central great plains late quaternary loess sections proximal to immediate source areas contain the brady soil a prominent marker separating late pleistocene peoria loess from holocene bignell loess farther from immediate dust source areas the brady soil and bignell loess are not recognizable in the fi eld on loess tablelands in these distal regions surface soils typically contain a prominent clay rich b horizon below a thick silty a horizon assuming top down pedogenesis this could be interpreted as a postglacial soil profi le formed in peoria loess with the b horizon produced by weathering and clay illuviation we propose a strikingly different interpretation in which the upper b horizon at distal sites is the brady soil a horizon that has been transformed by burial organic matter loss and modern subsoil structure formation processes the overlying modern a horizon represents bignell loess properties of the brady soil at proximal sites a distinctive burrowed zone high clay content and tio 2 zro 2 and low volcanic glass content can be traced to the b horizon in distal soils a decrease in smectite abundance above the brady soil at proximal sites is identifi able at the top of the clay rich b horizon in distal soils the spatial variation of clay content in loess and soil horizons is best explained by eolian sedimentation patterns the higher clay content in the brady soil and distal b horizons defi nes a fi ne grained zone that represents a late phase of peoria loess accumulation evidence of chemical weathering is minimal and illuvial clay is rare to absent in the clay rich b horizons illuvial clay does often occur deep in the solum and is related to the depth below the top of the brady soil the depth of occurrence of illuvial clay is not related to modern climate parameters although depth to secondary carbonate appears to be in equilibrium with modern climate upland soils in the central great plains are composite soils their properties are the result of a pedosedimentary history linked to regional climate change that has infl uenced sedimentation and pedogenesis since the late pleistocene

the behaviour of trace and rare earth elements ree during hydrothermal alteration in the rangan area central iran the rhyolitic dome in the rangan area has been subjected to hydrothermal alterations by two different systems 1 a fossil magmatic hydrothermal system with a powerful thermal engine of a deep monzodioritic magma 2 an active hydrothermal system dominated by meteoric water based on mineralogical and geochemical studies three different alteration facies have been identified phyllic advanced argillic and silicic with notable differences in ree and other trace elements behaviour in the phyllic alteration zone with assemblage minerals such as sericite pyrite quartz kaolinite lree are relatively depleted whereas hree are enriched the advanced argillic zone is identified by the presence of alunite jarosite and pyrophyllite as well as immobility of lree and depletion in hree in the silicic zone most of lree are depleted but hree patterns are unchanged compared to their fresh rock equivalents all the ree fractionation ratios la yb cn la sm cn tb yb cn ce ce cn and eu eu cn are low in the phyllic altered facies eu eu cn in both advanced and silicic facies is low too in all alteration zones high field strength elements hfse e g ti zr nb are depleted whereas transition elements e g v cr co ni fe are enriched geochemically speaking trace and rare earth elements behave highly selective in different facies

pre little ice age glacier fluctuations in garibaldi provincial park coast mountains british columbia canada holocene glacier fluctuations prior to the little ice age in garibaldi provincial park in the british columbia coast mountains were reconstructed from geomorphic mapping and radiocarbon ages on 37 samples of growth position and detrital wood from glacier forefields glaciers in garibaldi park were smaller than at present in the early holocene although some evidence exists for minor short lived advances at this time the first well documented advance dates to 7700 7300 14c yr bp subsequent advances date to 6400 5100 4300 4100 2900 and 1600 1100 14c yr bp some glaciers approached their maximum holocene limits several times during the past 10 000 years periods of advance in garibaldi park are broadly synchronous with advances elsewhere in the canadian cordillera suggesting a common climatic cause the garibaldi park glacier record is also broadly synchronous with the record of holocene sunspot numbers supporting previous research that suggests solar activity may be an important climate forcing mec

midge inferred holocene summer temperatures in southeastern british columbia canada abstract using fossil midge stratigraphies we inferred holocene summer temperatures at three subalpine lakes in eastern british columbia the late glacial sediment indicated cool conditions with an abundance of microspectra atrofasciata radialis type fossils at thunder lake and redmountain lake and sergentia at windy lake sergentia and tanytarsus lugens corynocera oliveri type were dominant in the early holocene together with chironomus at redmountain lake at thunder and windy lakes the early holocene was dominated by warm adapted taxa such as microtendipes quantitative midge temperature inference models reconstruct a 4 to 8 c rise in mean july air temperature for windy and thunder lakes at the pleistocene holocene transition early holocene temperatures averaged 3 to 4 c warmer than those extant today in contrast no long term temperature trend was evident at redmountain lake this site may not reflect actual trends in air temperature due to runoff from a persistent snow pack in the watershed comparison of midge and pollen data suggests an inverse relationship between summer temperature and precipitation through the middle to late holocene

holocene history of the bugaboo glacier british columbia sequences of tills buried paleosols wood and tephra in moraines provide a fairly complete record of holocene fluctuations of the bugaboo glacier in british columbia the oldest till known to be exposed in the lateral moraines apparently associated with an end moraine of the regionally known crowfoot advance is overlain by mazama tephra and is possibly early holocene but probably latest pleistocene in age a paleosol incorporating the tephra and capping this till developed during early to middle holocene time it represents the warm and or dry altithermal interval subsequent neoglacial advances deposited tills after 3 39 ka but before 3 07 ka in the period ca 2 5 1 9 ka and in the period from ca 0 9 ka to the nineteenth century recessional intervals are marked by paleosols and a former moraine gully now filled results of the bugaboo glacier study increase the resolution of known neoglacial history in the canadian cordillera and generally demonstrate the usefulness of lateral moraine stratigraphy

rare earth element mobility in vesicular lava during low grade metamorphism a geochemical comparison of basaltic relicts and spilitic domains from two burial metamorphosed flows in central chile of similar original composition and rich and poor in amygdules respectively demonstrates a relationship between initial vesicularity and rare earth element ree mobility during spilitization the ree were partly leached from permeable parts of the flows and precipitated in voids now amygdules and veinlets the ree excluding eu moved coherently in the highly amygdaloidal flow spilitic domains and amygdules inherited the basaltic ree pattern besides being characterized by a positive eu anomaly epidotes separated from amygdules have a ree distribution which mimics that of the basalt the absolute contents range widely suggesting local and or temporal ree variations in the metamorphic fluids pumpellyite differs by being strongly enriched in heavy ree similar ratios of th hf and ta in samples as contrasting as relict basalt and a geode are consistent with coherent leaching coherent mobility when established for a rock system can be used to elucidate for example whether minerals in cross cutting veins were formed by local redistribution or from introduced material

ree composition of primary and altered feldspar from the mineralized alteration zone of alkaline intrusive rocks western yunnan province china abstract the yao an gold deposit is situated northwest of kunming in yunnan province china is associated spatially with yao an alkaline intrusion the yao an gold mineralization may be divided into two ore stages the stage i sulfide stage fine grained pyrite chalcopyrite galena stringer veins and the stage ii oxide plus sulfide tectonic breccias and banded ore the stage i ores occur in the zones of pervasive potassic alteration the laser ablation icp ms technique was used to analyse ree in primary perthites and altered k feldspars of potassic alteration zone related to mineralization in the yao an gold deposit the primary perthites from yao an syenite porphyry all have similar ree features with light ree enrichment large positive eu anomalies and small but significant negative ce anomalies the ree patterns of altered k feldspars have broadly similar features but compared to the primary perthite have much higher ree concentrations and smaller positive eu anomalies these characteristics show that the hydrothermal fluids responsible for alteration were ree rich due to high levels of complex forming anions but had large negative eu anomalies and other features best ascribed to magmatic crystal fractionation these fluids were derived essentially from the magmatic system

le chaˆtelet gold bearing arsenopyrite deposit massif central france mineralogy and geochemistry applied to prospecting abstract the abundant data available on the geochemistry and mineralogy of the herynian gold deposit of le cha telet massif central france formed the basis for an analysis of the complex signature of a gold deposit and its hydrothermal alteration haloes this study describes the deposit and its environment at various scales the sulfide paragenesis of the le cha telet deposit resulted from several stages one of which was an event responsible for the deposition of au bearing arsenopyrite quartz veins the au is contained within the arsenopyrite lattice hydrothermal activity associated with these veins produced two superimposed alteration haloes an outer halo of kaolinite tosudite siderite alteration that developed at the expense of the plagioclase minerals and an inner halo of illite siderite alteration that affected all the minerals the hydrothermal alteration was followed by silicification of the wall rocks and then deposition of the au bearing arsenopyrite the hydrothermal alteration related to the event also generated geochemical signatures such as li b lree as sb au and w anomalies mineralogical studies and geochemical analyses of the hydrothermal facies show that 1 the anomalous li is trapped mainly in the tosudite lattice and to a lesser degree in the illite lattice and 2 the b is probably located in tosudite and illite lattices arsenic sb and au are contained in the arsenopyrite lattice during weathering the lithochemical signatures determined by the analytical techniques used in this study lose some of their specific characteristics depending on the original concentrations at deposit scale 0 25 1 0 km 2 b and li in the soill profiles indicate zones of hydrothermal alteration whereas as and au indicate zones of mineralization at a regional scale the association of au li and b in stream sediments is characteristics of this type of mineralization therefore in the hydrothermal setting described at le cha telet au as li and b appear at all scales to be dependable pathfinders for au bearing hydrothermal systems of possible economic interest

rare earth element distributions among minerals in a granodiorite and their petrogenetic implications a study of the distribution of lanthanide rare earths in a granodiorite from the eastern peninsular ranges batholith southern california reveals that a large fraction of the ree in this rock resides in the accessory phases sphene and allanite the minerals plagioclase alkali feldspar biotite epidote and apatite each contribute approximately 1 or less of each ree to the whole rock with the exception of eu for which plagioclase contributes 7 sphene and allanite together contain 80 to 95 of each ree each of these phases is zoned in ree concentration with substantial decreases from core to margin textural observations argue for relatively early saturation and precipitation of sphene and allanite in the magma ree zoning trends in sphene and allanite and unexpectedly low ree concentrations in largely later crystallizing minerals such as feldspar indicate that the precipitation of sphene and allanite significantly reduced ree concentrations in residual melts these results illustrate the potential that sphene and allanite have for controlling the behavior of ree in granitic magmas available information collectively suggest that the sampled granodiorite existed as a complete melt that the ree contained in the assemblage of phases were derived by direct crystallization from the melt and that the melt behaved essentially as a closed system once crystallization of the phases now present began close correspondences between the major and trace element chemistries of the granodiorite and phenocryst poor lavas from similar tectonic settings support these conclusions the ree pattern of the granodiorite melt appears to have originated at depth and is characteristic of its source regions and derivation mechanism the high liquidus temperature of a granodiorite melt 1000 c indicates the importance of mantle derived components within the sources of batholithic magmas in the peninsular ranges

soil climate system across the prairies in midwestern u s a abstract among mollisols across the prairie plains from eastern iowa to western kansas coincident systems of loess stratigraphy and sedimentology climate and soils are separated at 96 to 97 w longitude to the east udolls are formed peopeoria loess that dates back 14 000 radiocarbon years and are currently in a subhumid climate to the west ustrols are cormed in bignell loess that dates back to

nd isotopes demonstrate the role of contamination in the formation of coexisting quartz and nepheline syenites at the abu khruq complex egypt the petrogenesis of abu khruq an 89 ma alkaline ring complex of eastern egypt which is composed of alkali gabbros and both silica over and undersaturated syenites has been investigated major and trace element relationships and nd and sr isotope data are consistent with formation of the gabbros from an alkaline mafic magma that experienced extensive fractionation and all syenites from a felsic derivative of this melt the parental magma had an 87sr 86sr of 0 7030 and an 143nd 144nd of 0 512750 nd 4 4 indicating derivation from a depeleted mantle source the initial 143nd 144nd ratios are 0 512721 to 0 512748 for the gabbros 0 512739 to 0 512750 for the alkali syenites and trachytes 0 512717 to 0 512755 for the nepheline syenites and 0 512706 to 0 512732 for the quartz syenites in contrast analyzed precambrian granites from eastern egypt have generally lower 143nd 144nd ratios ranging from 0 51247 to 0 51261 or nd 0 8 to 1 7 for 89ma their nd model ages range from 775 to 935 ma and suggest there was no significant input of pre pan african crust in their formation among abu khruq rocks 143nd 144nd ratios indicate that the quartz syenites formed by open system crustal contamination processes whereas the nepheline syenites experienced little or no contamination modeling shows that contamination occurred at various stages affecting both mafic and more evolved compositions with input of about 20 crustal nd for the most contaminated samples the degree of contamination is related to the silica saturation of the quartz syenites simplified modeling of magma evolution within petrogeny s residua system demonstrates the ability of afc processes to cause a critically undersaturated magma to evolve across the feldspar join and produce oversaturated rocks the oversaturated syenites at abu khruq were produced in this manner whereas the nepheline syenites formed by fractionation without similarly large degrees of contamination the results have broad implications for the formation of subvolcanic complexes in continental settings beyond the important production of silica oversaturated compositions from crustal interaction they underscore the importance of crustal interactions in the formation of the various lithologies such interactions occur at various stages in the evolution of the magmas and as such are not strictly coupled with fractional crystallization while previous study of abu khruq has demonstrated extensive hydrothermal alteration of o and sr isotopes the present work shows that the nd isotope ratios were not significantly affected and thus reflect magmatic signatures this feature combined with relatively small corrections for initial ratios emphasizes the utility of nd isotopes for petrogenetic studies

core concepts of paleopedology abstract the current renaissance of scientific interest in paleosols has brought a variety of views and approaches to paleopedology two main approaches have emerged for the description and labelling of paleosols geosols are ancient land surfaces consisting of laterally connected suites of paleosols used for stratigraphic subdivision of sedimentary deposits pedotypes are individual kinds of paleosols named after localities like geosols pedotypes are used for mapping and describing individual profiles usually for the purpose of paleoenvironmental interpretation both pedotypes and geosols are field based labels for which genetic or interpretive considerations are at a minimum they can be interpreted using at least three distinct approaches taxonomic uniformitarianism is based on the assumption that a paleosol is formed in a similar environment to a surface soil of the same type the factor function approach interprets specific aspects of paleoenvironments from measured features of paleosols by comparison with paleoenvironmentally related variation of that feature in surface soils finally the process model approach seeks to recreate soil forming processes mathematically with input from measurable features of paleosols each approach has limitations such as the need for proxy features to classify paleosols in systems designed for surface soils the attainment of similar appearance of a paleosol by different pathways and the mathematical uncertainty of model assumptions the approaches of classification experimentation and modelling are not unique to paleopedology being widespread among other sciences fundamental to paleopedology however are the concepts of profiles and soilscapes of the past

rare earth element fractionation in authigenic illite smectite from late permian clastic rocks bowen basin australia implications for physico chemical environments of fluids during illitization ree analyses were performed on authigenic illitic clay minerals from late permian mudrocks sandstones and bentonites from the bowen basin australia the mixed layer illite smectite exhibit ree patterns with an obvious fractionation of the hree from the lree and mree which is an apparent function of degree of illitization reaction the highly illitic r greater than or equal to 3 illite smectite from the northern bowen basin show a depletion of lree relative to the less illitic r 0 and 1 clays in contrast an enrichment of hree for the illite rich clays relative to less illitic clays is evident for the southern bowen basin samples the north american shale composite normalized la lu sn ratios show negative correlations with the illite content in illite smectite and positive correlations with the delta 18 o values of the clays for both the northern and southern bowen basin samples these correlations indicate that the increasing depletion of lree in hydrothermal fluids is a function of increasing water rock ratios in the northern bowen basin good negative correlations between la lu sn ratios and illite content in illite smectite from the southern bowen basin suggest the involvement of fluids with higher alkalinity and higher ph in low water rock ratio conditions increasing hree enrichment with delta 18 o decrease indicates the effect of increasing temperature at low water rock ratios in the southern bowen basin results of the present study confirm the conclusions of some earlier studies suggesting that ree in illitic clay minerals are mobile and fractionated during illitization and that this fact should be considered in studies of sedimentary processes and in identifying provenance moreover our results show that ree systematic of illitic clay minerals can be applied as an useful technique to gain information about physico chemical conditions during thermal and fluid flow events in certain sedimentary basins c 2003 elsevier science b v all rights reserved

mineralogy and geochemistry of the argentiferous pb zn and cu veins of the colakli area elazig eastern turkey abstract the studied pb zn and cu veins occur as n s trending and vertically dipping features in quartz diorite of coniacian campanian elazig magmatic complex the complex has characteristics typical of arc magmatism and is composed of granitoids and volcanic subvolcanic and pyroclastic rocks the veins are 0 5 2 5 m thick and their lengths reach up to 750 m the ore of veins are either massive or disseminated in gangue of carbonate minerals quartz and barite the veins display two sets of mineral assemblages 1 pb zn veins are composed of galena freibergite barite sphalerite chalcopyrite pyrite a pb cl phase and native silver 2 cu veins have a mineral association of chalcopyrite pyrite galena sphalerite cubanite bismuthinite and fahlore the ore bodies are accompanied by narrow but intensely developed wall rock alterations of argillization carbonatization and silicification chemical analyses of ore samples indicate high pb ag sb zn ba and cu contents in the veins and high correlation values between pb ag pb ba pb zn sb ag cd sb and ba cd the ree geochemistry points to ore deposition under acidic conditions and probably as a product of the final stages of magmatism field microscopic and geochemical data also indicate that the ores are related to the last phases of the magmatic activity of the elazig magmatic complex

nomenclature and resolution in holocene glacial chronologies most quaternary research in canada during the first half of the twentieth century focused on pleistocene glaciation given the dramatic shifts in climate during the pleistocene it is not surprising that the holocene was viewed as a time of benign climate holocene climate variability was first recognized around the middle of the century when paleoecologists found evidence that the early part of the epoch was warmer and drier than the later part in 1970s and 1980s another generation of geologists geographers and botanists began to recognize more complexity in holocene climate and vegetation in western canada several millennial scale glacier advances postdating the early holocene warm interval were defined including the garibaldi phase 6 9 5 6 ka the tiedemann peyto advance 3 5 1 9 ka and the little ice age ad 1200 1900 subsequently application of dendrochronological techniques and stratigraphic studies in glacier forefields showed that the little ice age was itself more complex than previously thought during that 700 year period glaciers repeatedly advanced and retreated in response to climatic variability on time scales ranging from centuries to decades recent work shows that the glacier record of the garibaldi phase and the tiedemann and peyto advances are similar in complexity to the little ice age with multiple advances of glaciers separated by intervals of more restricted ice cover researchers have also identified other times in the holocene when glaciers expanded from restricted positions 8 20 4 90 3 80 and 1 70 1 40 ka continued research undoubtedly will reveal additional complexities but with what is currently known the appropriateness of terms such as tiedemann advance peyto advance and little ice age can be questioned only short periods of time separate these episodes as currently defined and it seems likely that intervals of restricted glacier cover within each of these millennial length intervals are just as long as the intervals separating them

rare earth element mobility in alteration pipes below massive cuzn sulfide deposits abstract a convincing demonstration of trace element mobility should satisfy two criteria 1 the range of trace element concentrations in the rock before and after alteration must be known with confidence and 2 the absolute abundances and the ratios of the mobile trace elements should vary between altered and unaltered rocks these criteria have been applied to the host felsic volcanics and alteration pipes associated with several canadian massive cu zn sulfide deposits although there is no evidence of rare earth element ree mobility in the pervasive low grade alteration envelopes adjacent to the deposits the light and middle ree lree and mree plus y have been systematically mobilized relative to the heavy ree hree and other trace elements in the alteration pipes beneath the ore zones there is evidence of minor lree and mree depletion in the most altered rocks at the south bay mine uchi lake and of significant lree depletion in the alteration pipe beneath the mattabi mine sturgeon lake however the strongest mobility is found at the kidd creek mine where the lree were leached from the rocks in the footwall stringer zone and redeposited in a metasomatic chlorite zone directly beneath the massive ore horizon and the mree and y were preferentially lost from the system producing distinctive chondrite normalized ree patterns with tb yb n ratios less than unity eu2 was found to be more mobile than the trivalent ree especially at kidd creek where there is a marked increase in the magnitude of the eu anomaly in the most altered samples high field strength elements such as u th hf and zr have not decoupled and apparently remained relatively immobile during all but the most intense alteration i e kidd creek preliminary data suggest that the degree of ree mobility increases with the size of the deposit thus ree mobility is a potentially useful method of distinguishing between small and large massive sulfide deposits at an early stage in exploration however this hypothesis requires further testing

extreme enrichment of rare earth elements in hard clay rocks and its potential as a resource abstract the xuanwei formation is widely distributed in western guizhou province nw china the lower section of which is primarily composed of gray white kaolinitic claystone interbedded with thin layers of grayish black carbonaceous mudstone that are extremely enriched with rare earth elements in order to determine the distribution patterns and existing status of ore forming elements in these rocks careful field investigations were performed along a selected geological profile and rock samples were collected and studied in terms of mineralogical and geochemical characteristics the results show that 1 rees are primarily enriched in the grayish white kaolinitic clay sediments and grayish black carbonaceous mudstone mineralogical analyses revealed kaolinite as the major mineral in rocks along with smaller amounts of smectite illite boehmite hornblende pyrophyllite calcite dolomite and or iron bearing minerals as well as a certain proportion of feldspar quartz crystal debris and non crystal debris 2 ree contents are 89 0 to 9965 ppm with an average of 1312 ppm the thickness of the host rock with ree higher than 1300 ppm is more than 4 m which is referred to as the ree enriched layer 3 the ree contents of bulk rocks exhibit a negative correlation with kaolinite positive correlations with boehmite hornblende and iron bearing minerals and weak positive correlations with smectite illite and pyrophyllite indicating that the ree might exist in an ion adsorption state in the space between the layers of clay minerals 4 compared with the underlying emeishan basalts the ree patterns of samples are quite similar but are enriched in both lree and hree the degree of enrichment of hree is relatively high based on these results a model is suggested where the ree enriched layers originated from the emeishan basalts and were controlled by the transportation and deposition of detritus from a paleo weathering crust the hard clay rocks have a significant resource potential as the contents of ree ga nb and zr are considerably higher than those in the weathering crust type of ree deposit

how element translocation by plants may stabilize illitic clays in the surface of temperate soils abstract it has been described several times that plant activity enriches the upper part of soil profiles in the inorganic elements they use for their growth si k ca mg this phenomenon called nutrient uplift or element translocation can counteract element loss via leaching in surface soils and may therefore impact clay mineral stability in upper soil horizons however apart from some studies in tropical ecosystems the link between element translocation and clay mineral stability has been poorly investigated yet the present work explores the consequences of element translocation on clay mineral stability in temperate grassland soils through the use of a geochemical model initially studies indicating that silicon and potassium translocation stabilizes 2 1 clay minerals and especially illitic clay minerals in surface soil were compiled using this analysis as a basis we propose a simple biogeochemical model linking plant primary productivity and clay mineral thermodynamic stability that allowed explaining how plant activity may stabilize clay minerals in the upper part of temperate grassland soils the influence of various parameters such as rainfall primary production elemental composition of plants or acidifying activity of roots was also investigated using the model the outputs of the model suggested that plant activity under certain conditions may well stabilize illitic clay in surface soils which opens wide perspectives for modellers and experimentalists

rare earth elements and hydrothermal ore formation processes abstract the geochemical behaviour of ree is influenced by nearly all important hydrothermal ore formation processes including fluid rock interactions fluid precipitations adsorption and scavenging onto particles and changes in fluid temperature pressure ph eh alkalinity and ligand concentration destabilization of ree complexes in response to these physicochemical changes and possible chemical crystallographic controls determine the concentration and distribution of ree within hydrothermal minerals mineraloids and amorphous phases alteration assemblages of intrusive related mineralisations may exhibit a wide range of ree distributions and ree fractionation trends the ree distribution within these hydrothermally altered lithologies will depend on the ree concentration in the rock and the fluid the partitioning behaviour of the ree between the rock phases and the fluid and the types of alteration reactions which take place reactive rocks such as carbonate rich lithologies of skarn deposits may gain or loose significant amounts of ree during fluid rock interactions ree geochemical investigations combined with fluid inclusion and stable isotope studies may point to the origin of alteration products and the source s of ore fluids ancient massive sulphide ores commonly exhibit anomalous eu concentrations similar to many recent submarine hydrothermal precipitates the recognition of hydrothermal fluid seawater sedimentary or volcanically derived ree distributions within ores chemical sediments and hydrothermally altered lithologies may help to constrain genetic modelling of massive sulphide deposits care should be taken with the interpretation of ree distributions from metamorphosed hydrothermal ore deposits becase metamorphic and diagenetic alteration reactions may change the ree distributions mobility of ree may occur during diagenesis of carbonate rich rocks and during the development of shear zones and migmatites in contrast very large fluid rock ratios are necessary to cause significant changes in ree patterns of silicate rich rocks during diagenesis and regional metamorphism