mineral and stable isotope compositions phase equilibria and 40ar 39ar geochronology from the iron skarn deposit in sangan northeastern iran abstract the sangan iron skarn deposit is located on the eastern edge of the sabzevar doruneh magmatic belt northeastern iran mineralization occurs at the contact between eocene igneous rocks and cretaceous carbonates the silicate dominant prograde skarn stage consists of garnet and clinopyroxene whereas the retrograde stage is dominated by magnetite associated with minor hematite phlogopite pyrite and chalcopyrite phase equilibria and mineral chemistry studies reveal that the skarn formed within a temperature range of 375 to 580 c and that the mineralizing fluid evolved from a hot low oxygen fugacity alkaline fluid during the silicate dominant stage to a fluid of relatively lower temperature and higher oxygen fugacity at the magnetite dominant stage the 18 o values of magnetite and garnet vary from 3 1 to 7 5 and 7 7 to 11 6 respectively the calculated 18 o h2o values of fluid in equilibrium with magnetite and garnet range from 9 8 to 11 1 and 10 1 to 14 8 respectively these elevated 18 o h2o values suggest interaction of magmatic water with 18 o enriched carbonates the high 34 s values 10 6 to 17 0 of pyrite separates from the sangan iron ore indicate that evaporites had an important role in the evolution of the hydrothermal fluid phlogopite separates from the massive ores yield 40 ar 39 ar plateau ages of 41 97 0 2 and 42 47 0 2 ma indicating that the skarn formation and associated iron mineralization was related to the oldest episode of magmatism in sangan at 42 ma eocene time marked a peak of magmatic activity and associated skarn in the post collisional setting in northeastern iran whereas oligo miocene magmatic activity and associated skarn in the urumieh dokhtar magmatic belt are related to subduction in addition skarn mineralization in northeastern and eastern iran is iron type but skarn mineralization in the urumieh dokhtar magmatic belt is copper iron and copper type

tectonic evolution of a part of the tethyside orogenic collage the kargi massif northern turkey the central part of the rhodope pontide fragment one of the major tectonic units in turkey provides critical data for evaluating the cimmeride and alpide evolution of the mediterranean tethysides tectonic events that affected the central part of the rhodope pontide fragment since the end of the paleozoic generated east west trending belts with the event of every episode redeforming and partly obliterating the structures of previous episodes this evolution may be conveniently described in terms of three major episodes 1 two different realms of pre dogger oceanic rocks are present in the area the northern realm coincided with main branch of paleo tethys that was being actively destroyed by south dipping subduction the southern realm the karakaya ocean a back arc basin related to this subduction began opening by rifting of a retroarc carbonate platform during the permo triassic to the west a continental domain with sparse magmatism seperated the two oceanic areas toward the east the two oceans become united by the wedging out of the continental domain these two pre dogger oceans closed during the lias and their remnants were emplaced between the southern margin of laurasia and the fragments of the cimmerian continent 2 the second episode partly overlapped the first with rifting south of the cimmerian continent fragment during the lias this rifting was followed by a transgression which covered the ruins of the cimmeride orogenic belt by the malm this rifting concurrently led to the development of the northern branch of the neo tethys and a south facing atlantic type continental margin a southerly thickening sedimentary prism developed on this margin during the lias to early cretaceous interval 3 the floor of the northern branch of neo tethys began to be consumed along the north dipping subduction zone beneath the previosly constructed continental margin this convergent margin generated a magmatic arc to the north and to the south a subduction accretion complex present width of which approaches 80 km to the south of the subduction accretion complex yet another convergent margin is indicated by the presence of the remnants of an ensimatic arc the northern branch of the neo tethys was totally consumed in the late cretaceous to eocene interval

iron oxide copper gold iocg deposits through earth history implications for origin lithospheric setting and distinction from other epigenetic iron oxide deposits the iron oxide copper gold iocg group of deposits initially defined following discovery of the giant olympic dam cu u au deposit has progressively become too embracing when associated deposits and potential end members or analogs are included the broader group includes several low ti iron oxide associated deposits that include iron oxide p rich iron oxide f and ree rich fe or cu au skarn high grade iron oxide hosted au cu carbonatite hosted cu ree and f rich and iocg sensu stricto deposits consideration of this broad group as a whole obscures the critical features of the iocg sensu stricto deposits such as their temporal distribution and tectonic environment thus leading to difficulties in developing a robust exploration model the iocg sensu stricto deposits are magmatic hydrothermal deposits that contain economic cu and au grades are structurally controlled commonly contain significant volumes of breccia are commonly associated with presulfide sodic or sodic calcic alteration have alteration and or brecciation zones on a large commonly regional scale relative to economic mineralization have abundant low ti iron oxides and or iron silicates intimately associated with but generally paragenetically older than fe cu sulfides have lree enrichment and low s sulfides lack of abundant pyrite lack widespread quartz veins or silicification and show a clear temporal but not close spatial relationship to major magmatic intrusions these intrusions where identified are commonly alkaline to subalkaline mixed mafic even ultramafic to felsic in composition with evidence for mantle derivation of at least the mafic end members of the suite the giant size of many of the deposits and surrounding alteration zones the highly saline ore fluids and the available stable and radiogenic isotope data indicate release of deep volatile rich magmatic fluids through devolatization of causative mantle derived magmas and variable degrees of mixing of these magmatic fluids with other crustal fluids along regional scale fluid flow paths precambrian deposits are the dominant members of the iocg group in terms of both copper and gold resources the 12 iocg deposits with 100 tonnes t resources are located in intracratonic settings within about 100 km of the margins of archean or paleoproterozoic cratons or other lithospheric boundaries and formed 100 to 200 m y after supercontinent assembly their tectonic setting at formation was most likely anorogenic with magmatism and associated hydrothermal activity driven by mantle underplating and or plumes limited amounts of partial melting of volatile rich and possibly metal enriched metasomatized early precambrian subcontinental lithospheric mantle sclm fertilized during earlier subduction probably produced basic to ultrabasic magmas that melted overlying continental crust and mixed with resultant felsic melts with devolatilization and some penecontemporaneous incorporation of other lower to middle crustal fluids to produce the iocg deposits preservation of near surface deposits such as olympic dam is probably due to their formation above buoyant and refractory sclm which resisted delamination and associated uplift most precambrian iron oxide p rich or magnetite apatite kiruna type deposits have a different temporal distribution apparently forming in convergent margin settings prior to or following supercontinent assembly it is only in the phanerozoic that iocg and magnetite apatite deposits are roughly penecontemporaneous in convergent margin settings the phanerozoic iocg deposits such as candelaria chile occur in anomalous extensional to transtensional zones in the coastal cordillera which are also the sites of mantle derived mafic to felsic intrusions that are anomalous in an andean context this implies that special conditions possibly detached slabs of metasomatized sclm may be required in convergent margin settings to generate world class iocg deposits it is likely that formation of giant iocg deposits was mainly a precambrian phenomenon related to the extensive mantle underplating that impacted on buoyant metasomatized sclm generally smaller and rarer phanerozoic iocg deposits formed in tectonic settings where conditions similar to those in the precambrian were replicated

cryogenic carbonates in cave environments a review abstract cryogenic cave carbonate ccc represents a specific type of speleothem its precipitation proceeds at the freezing point and is triggered by freezing induced concentration of solutes compared to classical speleothems stalagmites flowstones ccc occurs as accumulations of loose uncemented aggregates the grain sizes range from less than 1 m to over 1 cm in diameter karst groundwater chemistry and its freezing rate upon entering the cave are responsible for highly variable grain morphology rapid freezing of water results in the formation of ccc powders with grain size typically below 50 m slow freezing of water in caves usually in systems where the co2 escape is partly restricted e g ice covered water pools results in the formation of large mineral grains with sizes from less than 1 mm to about 20 mm the range of carbon and oxygen stable isotope compositions of ccc is larger than for a typical carbonate speleothem rapid freezing of water accompanied by a quick kinetic co2 degassing results in large ranges of 13c of the ccc powders between 10 and 18 pdb slow freezing of water with a restricted co2 escape results in gradual increase of 13c values from 9 to 6 pdb data ranges in individual caves are usually much more restricted accompanied by a 18o decrease of the precipitated carbonate overall range from 10 to 24 pdb these unusual trends of the carbonate 18o evolution reflect incorporation of the heavier 18o isotope into the formed ice new isotope data on ccc from three romanian ice caves allow better understanding of the carbon and oxygen isotope fingerprint in carbonates precipitated from freezing of bulk water cccs are proposed as a new genetic group of speleothems

an example of an accretionary forearc basin from northern central anatolia and its implications for the history of subduction of neo tethys in turkey deformed sedimentary sequences of late cretaceous middle eocene age located between the sakarya continent and the anatolian complex have been interpreted as the fill of a forearc basin the history and structure of this basin are critical for understanding the evolution of the neo tethyan subduction in the middle east i test and elaborate upon this interpretation on the basis of three basic outcrop areas of upper cretaceous lower tertiary sedimentary sequences confined to a northeast southwest trending belt in north west ankara these are the alci kinik and orhaniye areas they expose two different sedimentary sequences called alci and orhaniye in the alci area the sequence starts at the base with the continental red clastic rocks on the erosional surface of an underlying ophiolitic melange and continues upward into the shallow marine reefal buildup of the late maastrichtian age the upper half of the alci sequence is separated from its lower half by a local disconformity and dominated by the continental debris flow deposits composed mostly of volcanic material by contrast both the kinik and orhaniye areas are characterized by a thick continuous and coarsening upward sequence overlying conformably the underlying ophiolitic melange the lower half of the orhaniye sequence is dominated by a deep marine flysch its middle part by continental clastic material and the topmost part by the shallow marine reefal buildup lower contact relationships lithologic composition facies distribution internal structures and the regional tectonic settings of both sequences strongly suggest that the above mentioned three outcrops preserve the remnants of a peripheral accretionary forearc basin forming the north northwestern margin of the haymana polath accretionary forearc basin during middle campanian middle eocene time this peripheral basin is here named orhaniye accretionary forearc basin

the candelaria punta del cobre iron oxide cu au zn ag deposits chile several iron oxide rich cu au zn ag deposits define an approximately 5 km wide and at least 20 km long belt along the eastern margin of the coastal batholith near copiapo chile this belt includes the large candelaria mine and a group of middle and small sized mines in the punta del cobre district which is located about 3 km northeast of the candelaria deposit estimated geologic resources of the belt are on the order of 700 to 800 million metric tons mt at 1 0 percent cu the ore occurs in veins breccia and stringer bodies and in replacement bodies that are roughly concordant to bedding the orebodies are hosted mainly by volcanic and volcaniclastic rocks of the punta del cobre formation and in places also occur in volcaniclastic intercalations in the lower part of the overlying early cretaceous chanarcillo group most of the larger orebodies in the belt are located where northwest trending brittle faults intersect the contact between massive volcanic and volcaniclastic rocks these northwest faults and a major northeast trending ductile shear zone control portions of the ore of the candelaria deposit chalcopyrite is the only hypogene cu mineral the cu au ore is characterized by abundant magnetite and or hematite and by locally elevated concentrations of ag zn mo and light rare earth elements the ore is hosted mainly in zones with biotite potassium feldspar calcic amphibole epidote alteration at candelaria in the punta del cobre district ore in the deeper parts of the deposits is similarly associated whereas at shallow levels it occurs in zones of biotite potassium feldspar or albite chlorite calcite alteration mineralization at candelaria punta del cobre took place under relatively oxidized conditions manifested by the formation of specular hematite in parts of the district the pseudomorphic replacement of early specular hematite by magnetite during the main iron oxide formation marks a shift toward more reduced conditions or higher temperatures the bulk of the magnetite probably formed at temperatures of about 500 to 600 c the main sulfide stage followed with formation of pyrite and chalcopyrite at temperatures of 470 to 328 c subsequent martitization of the magnetite points to a temperature decrease cooling of the hydrothermal system is also indicated by the homogenization temperatures of 236 c of saline fluid inclusions in late stage calcite oxygen isotope combined with microthermometric data suggest that magmatic fluids or nonmagmatic fluids equilibrated with magmatic silicates were dominant during the main copper mineralization relatively light oxygen isotope signatures of fluids in equilibrium with late calcite suggest mixing with a nonmagmatic fluid e g basinal brines or meteoric waters during the late stages of hydrothermal activity sulfur isotope ratios of chalcopyrite pyrite pyrrhotite and sphalerite from the bronce candelaria las pintadas santos and socavon rampa deposits range from 34scdt values of 0 7 to 3 1 per mil this narrow range of sulfur isotope ratios near 0 per mil is consistent with sulfur of magmatic origin anhydrite from the candelaria mine paragenetically overlaps with chalcopyrite fluid inclusions in this anhydrite homogenize between 340 and 470 c and it has 34scdt values between 14 5 and 17 5 per mil a sulfate sulfide value of 13 4 per mil for a sample with coexisting anhydrite and chalcopyrite is consistent with sulfide sulfate fractionation at temperatures on the order of 400 c ore lead isotope signatures are homogeneous and similar to those of least altered volcanic host rocks and nearby intrusive rocks radiometric ages including new 40ar 39ar ages for hydrothermal alteration at candelaria point to a main cu au mineralization event at candelaria punta del cobre at around 115 ma the ages indicate that ore formation was broadly coeval with batholithic granitoid intrusions and with regional uplift they further imply that the cu au zn ag deposits formed at shallow crustal levels 3 km the stable isotope data the presence of previously reported hypersaline co2 rich fluid inclusions in the main cu ore stage and saline fluid inclusions in late stage calcite the oxidized character of the first ore fluid pulses and the mineralization age coeval with nearby intrusive activity are consistent with but not unequivocally evidence of magmatic fluid contribution into the hydrothermal system

effect of chemical composition of water on the oxygen 18 and carbon 13 signature preserved in cryogenic carbonates arctic canada implications in paleoclimatic studies abstract this study examines the 18o and 13c composition of cryogenic carbonate deposits in relation to the initial 18o 13cdic and chemical composition of the water from which it precipitated this study focuses on cryogenic calcites precipitated in relation to aufeis aggradation since it offers the possibility of examining the chemical and isotopic partitioning that occurs during freezing the studied aufeis are located in the western canadian arctic yt and nwt a region underlain mostly by limestone bedrock and southern baffin island nu an area of crystalline bedrock the results indicate that the 18o composition of cryogenic calcite from a carbonated environment are slightly depleted over that of the initial 18o of the parent water while those from a non carbonated environment are strongly depleted over the initial 18o of the parent water as a result of the lower calcite saturation state of the parent water this suggest that the 18o of cryogenic carbonates not only depends on the initial 18o composition of the parent water and the temperature at which the carbonate precipitated but also on the calcite saturation state of the parent water and kinetic inhibitions during calcite precipitation given that the aggradation of aufeis occurs under closed system freezing the residual water will become progressively depleted in 18o as a result of the removal of heavier isotopes in the ice in addition freezing imparts a concentration of solutes in the residual water which leads to an increase in calcite saturation index therefore carbonate precipitated in equilibrium from water that has a low calcite saturation index will have a highly depleted 18o composition over that of the initial 18o values of the parent water since the calcite saturation state will only be exceeded in the late stage of freezing by contrast solute and isotopic partitioning during freezing has little effect on the 13c of the cryogenic carbonates as it tends to reflect that of the initial 13cdic value of the parent water these findings have significant implications in the use of cryogenic carbonates in paleoclimate studies care must be taken when interpreting the 18o signature preserved in cryogenic carbonates since their signature might be modified by freezing prior to their precipitation which will lead to a lighter 18o composition of the cryogenic carbonates therefore it would be difficult to use the 18o composition of cryogenic carbonates as a direct proxy in paleoclimatic reconstruction unless details about the chemical composition of parent waters are known nevertheless the 13c composition of the cryogenic carbonates that precipitated under closed system conditions can allow insights into the different water sources contributing to carbonate precipitation

comparison of young volcanic associations of western and eastern anatolia formed under a compressional regime a review abstract turkey is characterised by widespread post oligocene volcanism in western anatolia volcanic activity began during the late oligocene early miocene in a compressional regime a widespread suite of andesitic and dacitic calc alkaline rocks was erupted in this period they were accompanied by locally developed high level granitic intrusions the abrupt change from n s compression to n s stretching in the middle miocene was accompanied by a gradual transition to alkali basaltic volcanism in eastern anatolia the collision related compressional tectonics and associated volcanic activity began in the late miocene to pliocene and continued almost without interruption into historical times one minor and two major volcanic phases may be distinguished an initial minor eruptive phase of basic and intermediate alkaline rocks was followed by widespread eruptions of andesitic and dacitic calc alkaline rocks during the pliocene partly penecontemporaneous with this a second more important major phase of volcanism involving alkaline and transitional lavas began and continued during the quaternary the calc alkaline lavas of both regions were erupted at a time when the compressional regime led to crustal thickening these lavas display many geochemical and isotopic signatures that may be interpreted in terms of contamination of magma involving continental crustal materials the alkaline lavas in both regions began during the final stage of the compressional regime and form two groups one group is geochemically and isotopically similar to the calc alkaline rocks and the other is more typically alkaline the volcanic evolution of these two regions of turkey followed a somewhat similar pattern producing highly contaminated calc alkaline lavas at the beginning and evolving towards uncontaminated alkaline lavas at the end

tectonic evolution of the gediz graben field evidence for an episodic two stage extension in western turkey western turkey is one of the most spectacular regions of widespread active continental extension in the world the most prominent structures of this region are e w trending grabens e g gediz and buyuk menderes grabens and intervening horsts exposing the menderes massif this paper documents the result of a recent field campaign field geological mapping and structural analysis along the southern margin of the modern gediz graben of pliocene 5 ma age this work provides field evidence that the presently low angle ductile brittle detachment fault is cut and displaced by the high angle graben bounding normal faults with total displacement exceeding 2 0 km the evolution of the n s extension along the gediz graben occurred during two episodes each characterized by a distinct structural styles 1 rapid exhumation of menderes massif in the footwall of low angle normal fault core complex mode during the miocene 2 late stretching of crust producing e w grabens along high angle normal faults rift mode during pliocene quaternary times separated by a short time gap the later phase is characterized by the deposition of now nearly horizontal sediments of pliocene age in the hanging walls of the high angle normal faults and present day graben floor sediments the evolution of extension is at variance with orogenic collapse and or back arc extension followed by the combined effect of tectonic escape and subduction rollback processes along the aegean cyprean subduction zone consequently it is misleading to describe the miocene sediments exhumed on shoulders of the gediz graben as simple graben fill

the role of magmatic sulfides and mafic alkaline magmas in the bingham and tintic mining districts utah this paper reports the existence of abundant magmatic sulfides in introduction latite lava vitrophyres and vent facies dikes from the bingham and the eruption of sulfur rich magmas from el chichon tintic districts in central utah these dikes and flows appear to luhr et al 1984 and mt pinatubo westrich gerlach be comagmatic with the ore related monzonite intrusions in addition 1992 in recent years has attracted attention to the limited analytical data suggest that the magmatic sulfides contain most of solubility of sulfur in intermediate magmas and the factors the cu and ag present in the latites magmatic sulfides are preserved potentially responsible for the formation of magmatic only in the least oxidized and least degassed lavas and vitrophyres sulfides and anhydrite however the occurrence of magpetrography of comagmatic dikes and intrusions suggests that matic sulfides in intermediate magmas is not universal resorption and oxidation s degassing of the globules may make many volcanic suites appear to be sulfide unsaturated the metal content available to a magmatic ore fluid minette and inasmuch as magmatic sulfides may sequester chalcophile shoshonite lavas occur in subordinate amounts in the latitic volcanic metals what would their presence signify in magmatic fields associated with latite monzonite intrusions and hydrothermal systems that formed porphyry cu and mesothermal vein ore deposits of the tintic ag pb zn cu au and bingham deposits do they sequester a significant portion of the porphyry cu au mo districts utah the ages chemical and magmatic cu pb zn ag and au thereby restricting modal compositions and field relations of the mafic alkaline lavas metal availability of subsequent ore forming fluids suggest that such magmas mixed and fractionated at shallow crustal we have examined the volcanic rocks from the tintic levels to form the ore related latites and monzonites the unaltered and bingham mining districts fig 1 utah and found mafic alkaline lavas in these districts are some of the most cu rich that almost all of the volcanic units contain magmatic lavas in the great basin province sulfides some quenched dikes and intrusion margins also have preserved magmatic sulfides comparable with those in the volcanic rocks several lines of evidence indicate that the volcanic and intrusive rocks are comagmatic keith et al 1989 1991 waite 1996 the tintic district and east tintic sub district in utah have recorded over

discussion the biogenic origin of needle fibre calcite by g cailleau et al 2009 sedimentology 56 1858 1875

evolution of the mo rich scheelite skarn mineralization at kozbudaklar western anatolia turkey evidence from mineral chemistry and fluid inclusions abstract the kozbudaklar scheelite skarn deposit in the tavsanli zone located approximately 22 km southeast of bursa is hosted by the triassic calcic inonu marble and eocene topuk pluton at least four stages have been recognized through skarn evolution scheelite skarn distributed close to the topuk pluton occurred during the early stage 1 and late stage 2 prograde substages the early prograde endo and exoskarn are composed of hedenbergite hd 96 joh 4 plagioclase an 55 64 and hedenbergite hd 61 94 joh 4 7 accompanied by calcic garnet grs 38 94 sps 1 5 alm 0 and scheelite pow 1 6 the second stage represents a relatively oxidized mineralogy dominated by diopside hd 16 48 joh 0 9 subcalcic garnet grs 24 92 sps 0 11 alm 0 31 and scheelite pow 7 32 the stage 3 and 4 mineral assemblages are characterized by few hydrous minerals in the retrograde stage and intense fracturing fluid inclusions from skarn rocks are indicative of multiple fluid events 1 low moderate salinity 5 16 wt nacl equiv inclusions homogenized dominantly by a high temperature 308 c to 600 c liquid phase in stage 1 fluid inclusions in an early garnet homogenized over a similar temperature range 440 c and 459 c into both liquid and vapor phases eutectic temperatures ranging from 61 7 c to 35 0 c that indicate the presence of h 2 o nacl mgcl 2 cacl 2 co 2 solutions 2 coexisting daughter mineral bearing high salinity 29 5 70 wt nacl equiv and vapor rich moderate salinity 11 5 16 7 wt nacl equiv inclusions that homogenized in the liquid phase by the disappearance of the vapor phase at a similar temperature range 308 c to 600 c in stage 2 eutectic temperatures range from 67 9 c to 51 8 c that shows the presence of h 2 o nacl co 2 ch 4 n 2 solutions 3 low moderate salinity 12 5 7 6 wt nacl equiv and temperature 320 c to 215 c inclusions homogenized by the liquid phase in stage 3 eutectic temperatures range from 59 5 c to 44 2 c indicating the presence of h 2 o nacl mgcl 2 cacl 2 co 2 solutions 4 inclusions of low salinity 9 9 0 9 wt nacl equiv and homogenization temperature 183 c to 101 c in stage 4 these data show that the kozbudaklar skarn deposit was formed in a magmatic hydrothermal system in this model carbonaceous fluids may have been exsolved from the plutonic rock during its emplacement and crystallization fluid inclusion data indicate that fluid boiling and immiscibility occurred at temperatures between 440 c and 459 c and pressures ranging from 50 mpa to 60 mpa based on hydrostatic considerations early scheelite was precipitated with relatively reduced mineral compositions as a result of depressurization mo rich scheelite with oxidized minerals formed via high salinity and vapor rich inclusions the second scheelite mineralization occurred in a normal hydrothermal system by an infiltration mechanism at pressures between approximately 40 and 1 5 mpa at shallow depths

an intrusion related origin for cu au mineralization in iron oxide copper gold iocg provinces major cu au deposits of iron oxide copper gold iocg style are temporally associated with oxidized potassic granitoids similar to those linked to major porphyry cu au deposits stable and radiogenic isotope evidence indicates fluids and ore components were likely sourced from the intrusions iocg deposits form over a range of crustal levels because co2 rich fluids separate from the magmas at higher pressures than in co2 poor systems thereby promoting partitioning of h2o cl and metals to the fluid phase at deep levels the magma fluid system cannot generate sufficient mechanical energy to fracture the host rocks as in porphyry systems and the iocg deposits therefore form in a variety of fault related structural traps where the magmatic fluids may mix with other fluids to promote ore formation at shallow levels the iocg deposits form breccia and fracture hosted mineralization styles similar to the hydrothermal intrusive breccias and sulphide vein systems that characterize many porphyry cu au deposits the fluids associated with iocg deposits are typically h2o co2 salt fluids that evolve by unmixing of the carbonic phase and by mixing with fluids from other sources in contrast fluids in porphyry systems typically evolve by boiling of moderate salinity fluid to produce high salinity brine and a vapor phase commonly with input of externally derived fluids these different fluid compositions and mechanisms of evolution lead to different alteration types and parageneses in porphyry and iocg deposits porphyry cu au deposits typically evolve through potassic sericitic and intermediate and or advanced argillic stages while iocg deposits typically evolve through sodic calcic potassic and carbonate rich stages and at deeper levels generally lack sericitic and argillic alteration the common association of porphyry and iocg cu au deposits with potassic oxidized intermediate to felsic granitoids together with their contrasting fluid compositions alteration styles and parageneses suggest that they should be considered as part of the broad family of intrusion related systems but that they are typically not directly related to each other

geology geochemistry and geochronology of fe oxide cu au mineralization associated with şamli pluton western turkey abstract the amli balikesir fe oxide cu au deposit one of several iron cu au deposits in western turkey is hosted by porphyritic rocks of the multi phase amli pluton and metapelitic metadiabasic rocks of karakaya complex two successive mineralization events are recognized in the area as i early magnetite and sulfide and ii late hematite goethite native copper au alteration associated with the mineralization in amli is characterized by four distinct mineralogical assemblages they are in chronological order of formation 1 plagioclase early pyroxene scapolite 2 garnet late pyroxene 3 chlorite epidote and 4 chalcedony calcite alteration geochemical isotopic sr nd o s and geochronological ar ar data from alteration and magmatic rocks suggest a temporal and genetic link between the multiphase amli pluton and the hydrothermal system that controls the fe oxide cu au mineralization 40 ar 39 ar geochronology on hornblende and biotite separates of the amli pluton yielded an age range between 23 20 0 50 and 22 42 0 11 ma overlapping with 40 ar 39 ar age of 22 34 0 59 ma from alteration the close spatial and temporal associations of amli mineralization with porphyritic intrusions pervasive ca rich alteration calcic plagioclase andraditic garnet diopsidic pyroxene scapolite and epidote are considered as common features akin to calcic assemblages in typical iocg deposits besides abundant low ti 0 5 magnetite hematite high cu moderate au up to 8 82 ppm association structural control and lithologic controls of mineralization low s sulfide content chalcopyrite pyrite in the deposit and the derivation of causative magma from subduction modified subcontinental lithospheric mantle under a transpressional to transtensional regime are collectively considered as the features in favor of iocg type mineralization for the amli deposit

u pb sims dating of synkinematic granites timing of core complex formation in the northern anatolide belt of western turkey secondary ion mass spectrometry sims u th pb dating of magmatic zircon from the synkinematic egrigoz and koyunoba granites and a leucogranite dyke dates core complex formation in the northern anatolide belt of western turkey at 24 19 ma the granites intrude into the footwall of the simav detachment and are strongly elongated in the nne direction parallel to tectonic transport on the detachment although large parts of the granites are undeformed localized mylonitic to ultramylonitic deformation occurs directly beneath the simav detachment and preserves evidence of progressive deformation from ductile to brittle conditions oscillatory zoned rims of long prismatic zircon from the egrigoz and koyunoba granites yield identical and well constrained intrusion ages of 20 7 0 6 ma and 21 0 0 2 ma whereas inherited grains range from palaeoproterozoic 2972 13 ma to neoproterozoic 653 6 ma to 500 5 ma in age a leucogranite dyke yields an intrusion age of 24 4 0 3 ma with inherited neoproterozoic 640 7 ma to 511 6 ma grains our data in conjunction with published 40 ar 39 ar biotite ages indicate very rapid cooling greater than c 200 c ma 1 for the granites during and after synkinematic emplacement

k ar ages of metamorphic rocks at the base of the samail ophiolite oman hornblendes from amphiobolities in the sheet of metamorphic rocks beneath the peridotite member of the samail ophiolite and phyllites farther from the peridotite contact have weighted mean sup 40 ar sup 39 ar total fusion ages of 90 0 3 0 m y and 79 5 3 0 m y respectively the amphibolities represent the first tectonic slice welded to the base of the samail ophiolite after it was detached from the tethyan oceanic crust formation of the amphiobolities occurred no more than 3 to 7 m y after crystallization of plagiogranite in the ophiolite the phyllites represent another tectonic slice of ocean floor sediments welded to the ophiolite as it was transported further from the tethyan spreading axis the k ar ages suggest assuming a half spreading rate of 2 to 5 cm yr that detachment of the samail ophiolite and formation of amphibolite facies rocks occurred no more than 60 to 350 km from spreading center using the same spreading rate one can calculate a minimum half width of 300 to 750 km for the tethyan ocean during the late cretaceous

petrochemistry of the south marmara granitoids northwest anatolia turkey post collision magmatic rocks are common in the southern portion of the marmara region kapidag karabiga gonen yenice can areas and also on the small islands marmara avsa pasalimani in the sea of marmara they are represented mainly by granitic plutons stocks and sills within triassic basement rocks the granitoids have ages between late cretaceous and miocene but mainly belong to two groups eocene in the north and miocene in the south the miocene granitoids have associated volcanic rocks the eocene granitoids do not display such associations they are both granodioritic and granitic in composition and are metaluminous calc alkaline medium to high k rocks their trace elements patterns are similar to both volcanic arc and calc alkaline post collision intrusions and the granitoids plot into the volcanic arc granite vag and collision related granite areas colg of discrimination diagrams the have high 87sr 86sr 0 704 0 707 and low 143nd 144nd 0 5124 0 5128 during their evolution the magma was affected by crustal assimilation and fractional crystallization afc nd and sr isotopic compositions support an origin of derivation by combined continental crustal afc from a basaltic parent magma a slab breakoff model is consistent with the evolution of south marmara sea granitoids

the hypogene iron oxide copper gold mineralization in the mantoverde district northern chile the mantoverde iron oxide copper gold iocg district northern chile is known for its cu production from supergene ores recently exploration outlined an additional hypogene ore resource of 440 mt with 0 56 percent cu and 0 12 g t au the hypogene sulfide mineralization occurs mainly as chalcopyrite and pyrite typically in specularite or magnetite cemented breccias and associated stockworks the host rocks underwent variably intense k feldspar alteration chloritization sericitization silicification and or carbonatization a district scale na ca alteration is absent the iocg mineralization in the district shows a strong tectonic control by northwest to north northwest trending brittle structures large cu sulfide rich veins or cu sulfide cemented breccias are absent therefore head grades of 4 percent cu are an exception there is a positive correlation between cu and au grades gold is probably contained mostly in chalcopyrite and pyrite elevated concentrations of light rare earth elements lree occur locally but are attributed to redistribution of lree within the deposits rather than to derivation from external sources the cu au ores in the mantoverde district are low in u and have relatively low contents in heavy metals that are potentially hazardous to the environment such as as avg 14 ppm hg 5 ppm or cd 0 2 ppm the sulfur isotope ratios of chalcopyrite from the iocg deposits lie between 5 6 and 8 9 per mil 34svcdt they show systematic variations within the district which are interpreted to reflect relative distance to inferred fluid conduits and the level of deposition within the hydrothermal system most initial 87sr 86sr values of altered volcanic rocks and hydrothermal calcite from the mantoverde district are between 0 7031 and 0 7060 and are similar to those of the igneous rocks of the region lead isotope ratios of chalcopyrite are consistent with pb and by inference cu derived from early cretaceous magmatism the sulfur strontium and lead isotope data of chalcopyrite calcite gangue or altered host rocks respectively are compatible with a genetic model that involves cooling of metal and sulfur bearing magmatic hydrothermal fluids that mix with meteoric waters or seawater at relatively shallow crustal levels an additional exotic sulfur input is likely though not required for the copper mineralization apart from the iocg deposits there are a number of smaller magnetite apatite bodies in the district these are geologically similar to the cu au bearing magnetite bodies but are related to splays of the north south trending atacama fault zone and differ in alteration and texture

weathering of pge sulfides and pt fe alloys in the freetown layered complex sierra leone fresh and weathered rocks and saprolite from horizon b of the freetown layered complex contain platinum group minerals pgm the pgm in the fresh rocks are 1 7 m across including cooperite pts isoferroplatinum pt3fe minor tetraferroplatinum ptfe tulameenite pt2fecu os bearing laurite rus2 and other base metal sulfide bms bearing pgm the weathered rocks contain fewer of those pgm but a high proportion of disordered cu pd bearing pt fe alloys the saprolite hosts scarce smaller 1 3 m ordered ptfe and disordered ptfe3 the pt fe alloys became increasingly fe rich as weathering proceeded pt fe oxides appeared during weathering copper sulfides associated with the primary pgm and cooperite with 3 pd were destroyed to provide the minor cu and pd found in some of the disordered pt fe alloys platinum and pd bearing saprolites have retained the original rock fabric and to a depth of about 2 m surround residual rocks that show progressive weathering corestones ground water passing through the saprolite has transported pt and pd and probably au in solution down slope into saprolite over unmineralized rocks transport is marked by changes in the pt pd ratio indicating that the metals have moved independently palladium is present in marginally higher concentrations in the deeper saprolite than in the corestones suggesting some retention of pd in the deeper saprolite platinum and pd are less concentrated in the upper saprolite than the deeper saprolite indicating surface leaching alteration occurred over a long period in an organic and microbial rich environment that may have contributed to the leaching and transport of pge

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

late palaeozoic marginal basin and subduction accretion the palaeotethyan kure complex central pontides northern turkey the kure complex located in the central pontides of northern turkey is a c 20 km thick pile of thrust imbricated deep sea sediments intercalated with a dismembered ophiolite the ophiolitic rocks include serpentinized harzburgite massive gabbro cumulate and isotropic sheeted dykes and basic volcanic rocks the extrusive rocks are mainly pillow lavas sheet flows and lava breccias geochemical evidence of immobile major and trace elements and pyroxene chemistry indicate mid ocean ridge mor and volcanic arc basalt vab compositions and suggest that the kure ophiolite was generated above a subduction zone chrome spine1 analysis also supports this interpretation in some thrust sheets the extrusives are depositionally overlain by hemi pelagic shales passing up into terrigenous turbidites and shales which are up to several hundred metres thick in intact successions cyprus type massive sulphides interpreted as precipitates from black smokers are located along the lava sediment contact individual intact sediment units up to several kilometres thick within the kure complex are separated by narrow up to 10 m wide zones of intense shearing layer parallel extension and melange formation asymmetrical folds reverse faults thrusts and duplex structures throughout the kure complex indicate mainly northwards emplacement the kure complex is thought to have opened in the late palaeozoic as a marginal basin above a northward dipping palaeotethyan subduction zone located along the southern margin of eurasia the kure marginal basin later closed in response to inferred southward subduction leading to development of an accretionary prism prior to late jurassic time the kure complex is unlikely to represent the main palaeotethyan suture as has been suggested in some earlier tectonic reconstructions regional comparisons with dobrogea crimea and caucasus suggest the kure basin opened then closed along a south eurasia active margin

mineralogy fluid inclusions and carbon isotopes of the kaman iron deposits central anatolia turkey implication for ore genesis and hydrothermal evolution abstract the kaman iron deposits are located in central anatolia and are hosted by the triassic bolcadag marble and upper cretaceous celebi granitoid magnetite mineralization manifests as rhythmic banded and irregular lenses which can be massive or disseminated within calcic marble and skarn zones six main paragenetic stages of skarn formation and ore deposition have been identified 1 na ca alterations composed of plagioclase an4 31 and actinolite 2 a prograde stage representing oxidized mineralogy dominated by diopside di62 98joh0 4 grossular andradite grs15 84alm4 8sps1 4 and magnetite 3 a retrograde stage consisting of epidote ep51 62cli38 49 magnetite calcite quartz and less abundant sulfides and chlorite 4 a quartz calcite pyrite stage containing pyrite quartz calcite and chlorite and 5 6 quartz carbonate and supergene stages characterized by quartz calcite hematite and chalcedony goethite fluid inclusion and carbon isotope studies have shown that the prograde stage formed from moderate high salinity 7 1 to 70 wt nacl eq and high temperature 339 to 600 c fluids liquid and vapor rich inclusions in an early garnet were homogenized in the liquid and vapor phases in a similar temperature range 513 and 529 c the 18o and 13c of calcites that accompany rhythmic banded magnetite ranged from 22 82 to 23 50 and 4 68 to 5 31 respectively the retrograde stage was formed from low high salinity 2 9 to 45 4 wt nacl eq and low high temperature 167 to 459 c fluids the 18o and 13c of skarn calcites ranged from 4 34 to 15 86 and 3 57 to 0 23 respectively the quartz calcite pyrite stage was formed from low salinity 3 1 7 5 wt nacl eq and temperature 171 392 c fluids the 18o and 13c values were 2 38 and 2 43 respectively the quartz carbonate stage formed from low salinity 3 6 to 5 7 wt nacl eq and temperature 129 to 169 c in all phases the eutectic and clathrate melting temperatures ranged from 59 5 to 52 2 c and 4 4 to 12 0 c respectively this indicates that the solutions contain h2o nacl cacl2 mgcl2 co2 these fluid inclusion data suggest that fluid boiling occurred under pressures between 60 and 70 mpa based on hydrostatic consideration during the prograde stage the main magnetite deposition occurred following boiling with rising salinity and temperature magmatic hydrothermal fluids and in the pressure range of 15 to 50 mpa depletion in 13c was attributed to high temperature fluid infiltration and indicates an open system volatilization process it is suggested that the retrograde stage had developed in two episodes with the carbofracturing effect triggered by co2 the carbon isotope data of calcites indicate the mixing of low temperature metasomatic and meteoric water in later stages the mineralogy microthermometry and carbon isotope results reveal that kaman iron deposits were developed by a combination of processes such as contact infiltration metasomatism fluid rock interaction cooling and fluid mixing as a result of decreasing pressure

tectonic setting petrology and geochronology of jadeite glaucophane and chloritoid glaucophane schists from north west turkey the north west turkish blueschists represent a subducted passive continental margin sequence dominated by metaclastic rocks and marble the depositional age of the blueschist protoliths are probably palaeozoic to mesozoic while the age of the high pressure low temperature metamorphism is late cretaceous blueschists are tectonically overlain by a volcanosedimentary sequence made up of accreted oceanic crustal material that locally shows incipient blueschist metamorphism and by spinel peridotite slices the metaclastic rocks with regional jadeite and glaucophane which comprise the lower part of the blueschist unit make up an over 1000 m thick coherent sequence in the kocasu region of north west turkey rare metabasic horizons in the upper parts of the metaclastic sequence with sodic amphibole iawsonite but no garnet indicate lawsonite blueschist facies metamorphism the blueschist metaclastics in the kocasu region are practically free of calcium and ferric iron and closely approximate the nfmash system in bulk composition two low variance mineral assemblages with quartz and phengite are jadeite glaucophane chlorite paragonite and chloritoid glaucophane paragonite the metaclastics comprise up to several metres thick layers of jadeite schist with quartz phengite and nearly 100 mol jadeite phase relations in the metaclastics show that the chloritoid glaucophane assemblage even in fe2 rich compositions is stable in the jadeite stability field in the nfash system the above assemblage without the accompanying garnet has a narrow thermal stability field mineral equilibria in the metaclastics involving chloritoid glaucophane jadeite paragonite and chlorite indicate metamorphic p t conditions of 20 2 kbar and 430 30 d c yielding geothermal gradients close to 5d c km 1 one of the lowest geotherms recorded blueschists in the kocasu region which have been buried to 70 km depth are tectonically overlain by the volcanosedimentary sequence and by peridotite buried not deeper than 30 km phengites from two jadeite schists were dated by ar ar laser probe they give an age of 88 5 0 5 ma interpreted as the age of metamorphism blueschists and the overlying peridotite bodies are intruded by 48 53 ma old granodiorite bodies that were emplaced at 10 km depth this suggests that the exhumation of blueschists by underplating of cold continental crust and normal faulting at the blueschist peridotite interface occurred during the late cretaceous to palaeocene 88 53 ma

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

geochemistry mineralogy and genesis of the ayazmant fe cu skarn deposit in ayvalik balikesir turkey abstract the ayazmant fe cu skarn deposit is located approximately 20 km se of ayvalik or 140 km n of izmir in western turkey the skarn occurs at the contact between metapelites and the metabasites of the early triassic kinik formation and the porphyritic hypabyssal intrusive rocks of the late oligocene kozak intrusive complex the major trace and rare earth element geochemical analysis of the igneous rocks indicate that they are i type subalkaline calc alkaline metaluminous i type products of a high level magma chamber generated in a continental arc setting the 40 ar 39 ar isochron age obtained from biotite of hornfels is 20 3 0 1 ma probably reflecting the age of metamorphic bimetasomatic alteration which commenced shortly after intrusion into impure carbonates three stages of skarn formation and ore development are recognized 1 early skarn stage stage i consisting mainly of garnet with grossular rich gr 75 79 cores and andradite rich gr 36 38 rims diopside di 94 97 scapolite and magnetite 2 sulfide rich skarn stage ii dominated by chalcopyrite with magnetite andraditic garnet ad 84 89 diopside di 65 75 and actinolite and 3 retrograde alteration stage iii dominated by actinolite epidote orthoclase phlogopite and chlorite in which sulfides are the main ore phases 40 ar 39 ar age data indicate that potassic alteration synchronous or postdating magnetite pyroxene amphibole skarn occurred at 20 0 0 1 ma the high pyroxene garnet ratio plus the presence of scapolite in calc silicate and associated ore paragenesis characterized by magnetite hematite chalcopyrite and bornite suggests that the bulk of the ayazmant skarns were formed under oxidized conditions oxygen isotope compositions of pyroxene magnetite and garnet of prograde skarn alteration indicate a magmatic fluid with 18 o values between 5 4 and 9 5 on the basis of oxygen isotope data from mineral pairs the early stage of prograde skarn formation is characterized by pyroxene di 94 97 magnetite assemblage formed at an upper temperature limit of 576 c the lower temperature limit for magnetite precipitation is estimated below 300 c on the basis of magnetite calcite pairs either as fracture fillings or massive ore in recrystallized limestone marble the sulfide assemblage is dominated by chalcopyrite with subordinate molybdenite pyrite cubanite bornite pyrrhotite galena sphalerite and idaite gold copper mineralization formed adjacent to andradite dominated skarn which occurs in close proximity to the intrusion contacts native gold and electrum are most abundant in sulfides as fine grained inclusions grain size with varying from 5 to 20 m sulfur isotope compositions obtained from pyrrhotite pyrite chalcopyrite sphalerite and galena form a narrow range between 4 8 and 1 6 suggesting the sulfur was probably mantle derived or leached from magmatic rocks geochemical data from ayazmant shows that cu is strongly associated with au bi te se cd zn pb ni and co the ayazmant mineralizing system possesses all the ingredients of a skarn system either cogenetic with or formed prior to a porphyry cu au mo system the results of this study indicate that the aegean region of turkey has considerable exploration potential for both porphyry related skarns and porphyry cu and au mineralization

a fore arc origin for the thrace basin nw turkey hydrocarbon bearing thrace basin occupies much of the european part of turkey the middle eocene to oligocene sequence in the centre of the basin exceeds 9 km in thickness based on the stratigraphy structure and the regional context of this basin we propose that it developed as a fore arc basin between the medial eocene and the oligocene above the northward subducting intra pontide ocean its post miocene history has been dominated mainly by wrench tectonics resulting from the activity of the now deactivated northwestern strand of the present day north anatolian fault zone

coeval plutonism and metamorphism in a latest oligocene metamorphic core complex in northwest turkey a metamorphic core complex of latest oligocene age crops out in the kazdag mountain range in northwest turkey the footwall of the core complex consists of gneiss amphibolite and marble metamorphosed at 5 1 kbar and 640 50 c the average muscovite and biotite rb sr ages from the gneisses are 19 ma and 22 ma respectively and imply high temperature metamorphism during latest oligocene times the hangingwall is made up of an unmetamorphosed lower tertiary oceanic accretionary melange with upper cretaceous eclogite lenses the hangingwall and footwall are separated by an extensional ductile shear zone two kilometres thick mylonites and underlying high grade metamorphic rocks show a n trending mineral lineation with the structural fabrics indicat ing down dip top to the north shear sense the shear zone the accretionary melange and the high grade metamorphic rocks are cut by an undeformed granitoid with a 21 ma rb sr biotite age analytically indistinguishable from the rb sr biotite ages in the surrounding footwall gneisses the estimated pressure of the metamorphism and that of the granitoid emplacement indicate that the high grade metamorphic rocks were rapidly exhumed at 24 ma from a depth of 14 km to 7 km by activity along the shear zone the subsequent exhumation of the metamorphic rocks to the surface occurred during pliocene quaternary times in a transpressive ridge between two overstepping fault segments of the north anatolian fault zone the high grade metamorphic rocks of the kazdag range are surrounded by voluminous calc alkaline volcanic and plutonic rocks of late oligocene early miocene age which formed above the northward dipping hellenic subduction zone the magmatic arc setting of the core complex and stratigraphic evidence for subdued topography in northwest turkey prior to the onset of extension suggest that the latest oligocene regional extension was primarily related to the roll back of the subduction zone rather than to the gravitational collapse

a primary platinum occurrence in the freetown layered intrusion sierra leone the primary source of the alluvial platinum group minerals pgm of the freetown layered intrusion sierra leone has been unknown since their discovery 70 years ago this is a report on work in progress to establish a primary occurrence related to the igneous layering new whole rock major and minor element analyses and precious metal assays show that at key horizons there is a significant change in the silicate mineral compositions and in cu cr and ni as well as in pt and pd comparable to those encountered in other pgm bearing layered intrusions anomalous 0 1 to 0 4 g t pt levels occur in pyroxene troctolites which maintain these levels along strike

menderes massif western turkey structural metamorphic and magmatic evolution a synthesis the menderes massif covers large areas in western turkey the better understanding of its tectono metamorphic history would provide insight for the alpine evolution of western turkey and the entire eastern mediterranean region this paper summarizes the available literature on the metamorphic rocks of western turkey and that of the menderes massif with special reference and emphasis to the papers presented in the special issue

the carpatho balkanides and adjacent area a sector of the tethyan eurasian metallogenic belt the tethyan eurasian metallogenic belt temb was formed during mesozoic and post mesozoic times in the area of the former tethyan ocean on the southern margin of eurasia with the afro arabian and indian plates to the south it extends from western mediterranean via the alps and southeastern europe through the lesser caucasus the hindu kush and the tibet plateau to burma and sw indonesia linking with the west pacific metallogenic belt the carpatho balkan region is one of the sectors of the temb characterized by some specific features the emplacement of ore deposits is related to a definite time interval and to specific tectonic settings such as

subduction complex of pre jurassic age northern anatolia turkey in northern anatolia a zone of pre liassic orogenic deformation is located mainly between the internal anatolian massifs and the north anatolian fault this belt consists of metamorphic rocks in blueschist greenschist and amphibolite facies and an ophiolitic dynamometa morphic melange the metamorphic rocks represent deformed and metamorphosed oceanic crust and upper mantle whereas the melange rocks originated in diverse environments in abyssal plain trench arc trench gap and forearc environments the evolution of these assemblages is interpreted as a product of subduction probably associated with the closure of the tethys subduction related deformation and meta morphism terminated diachronously from pre late triassic in the west to pre late liassic in the east probably as a result of the diachronous closure of the tethys

the emplacement history of granitic intrusions into the upper crust forceful to passive emplacement of the early miocene solarya pluton nw turkey as a case study abstract post collisional magmatism in western anatolia produced several granitic bodies represented by shallow level intrusions in this study we present field geochronology and geothermo barometry results of the solarya pluton sp nw turkey in order to better understand its emplacement into the different levels of the crust the sp consists of three main plutonic members showing different textural properties the northern part of the plutonic body is represented by k feldspar megacrystalline granodiorite kfmg with distinct porphyritic texture and southern part is made up of microgranite granodiorite mgg displaying microgranular texture whereas haplogranite which displays graphic granophyric textures is represented by a thin aureole between the sp and basement rocks field relations petrography and geothermo barometry studies combined with 40ar 39ar and u pb zircon dating results suggest that different members of the sp were emplaced into different levels of crust with different mechanisms the kfmg 40ar 39ar 23 2 ma u pb 21 8 ma began its emplacement forcefully in the relatively deeper levels in the crust av 1 65 kbar av 797 c 6 1 km depth after this stage mgg 40ar 39ar 22 6 ma u pb 21 2 ma was passively emplaced into the shallow levels av 0 69 kbar av 745 c 2 4 km depth via cauldron subsidence and in the latter stages the sheet intrusive rocks haplogranite 40ar 39ar 21 6 ma and hypabyssal association were emplaced into the ring faults at 1 5 km depth forceful to passive emplacement of the sp into the upper crust occurred under aegean extensional tectonics our study contributes to examination of the granite ascent and emplacement within other extensional provinces worldwide

plate boundary kinematics in the alps motion in the arosa suture zone the arosa zone forms a melange complex along the penninic austroalpine boundary and belongs to the main alpine suture zone accretion and plate collision occurred during cretaceous and lower tertiary time a mixture of ophiolitic rocks and pelagic sediments is imbricated with flysch and blocks of austroalpine continental derivation we present a description of deformation structures an analysis of strain and a kinematic interpretation based on structural work deformation histories of imbricates show a translation path that was west directed between ca 110 and 50 ma and north directed thereafter the kinematics of the arosa zone agrees with the recently deduced displacement history of the austroalpine units in the eastern alps during the cretaceous orogeny this calls for a predominantly top to the west imbrication of austroalpine and penninic units and is in contradiction to what is inferred in most models of the eastern alps a direct relation between the deformation along the austroalpine margin and relative plate motion existed

the mount kozak magmatic complex western anatolia abstract the mount kozak igneous complex is located close to the towns of ayvalik bergama and burhaniye in the western anatolia turkey magmatic activity occurred during the late oligocene early miocene beginning with the emplacement of the kozak pluton sheet intrusive rocks formed around it coevally they are surrounded by the volcanic rocks partly contemporaneously with the emplacement of the granitic rocks during the early miocene the upper oligocene lower miocene magmatic rocks of the kozak region are represented by a high k calc alkaline suite of predominantly intermediate and acidic composition their geochemical characteristics suggest that the magmas are hybrid and were formed from a similar source representing mantle derived magmas contaminated by crustal materials the cogenetic plutonic rocks the hypabyssal rocks and the overlying volcanic associations are related to one another in space and time and appear to have been connected to a shallow level granitic intrusion in a caldera collapse setting the calc alkaline magmatic activity waned during the middle miocene when the volcanism was rejuvenated during the late miocene pliocene alkaline basalt lavas were formed as fissure eruptions

contribution of mafic melt to porphyry copper mineralization evidence from mount pinatubo philippines and bingham canyon utah usa mount pinatubo in the philippines known for its cataclysmic eruption in 1991 hosts several porphyry copper deposits and active geothermal systems an underlying mafic melt supplied much of the sulphur for the dacitic magma and its injection into the dacitic magma chamber triggered the eruption the eruption caused purging of the sulphur rich fluid from the dacite to the atmosphere and extensive fracturing similar events took place at bingham canyon utah site of the largest copper and gold deposit in north america at 38 ma the bingham canyon mineralization took place beneath an active stratovolcano and pyroclastic flows contemporaneous with the mineralization show evidence for magma mingling ascent of mafic melt supplied sulphur and chalcophile elements to the felsic magma which consolidated to form the bingham stock and its underlying magma chamber injections of the mafic melt caused periodic eruptions of felsic magma to form the stratovolcano and deposition of sulphide minerals in highly fractured rocks in and around the stock

petrogenesis and time progressive evolution of the cenozoic continental volcanism in the biga peninsula nw anatolia turkey abstract the post collisional cenozoic magmatic activity in the biga peninsula nw anatolia started in the middle eocene 45 3 0 9 ma and lasted continuously until the late miocene 8 32 0 19 ma with minor punctuations producing widespread volcanoplutonic complexes these magmatic suites are characterized by calc alkaline high k calc alkaline shoshonitic mildly alkaline and alkaline series the middle eocene to middle miocene lavas have high lile lree lile hfse and 87sr 86sr i 0 7046 0 7087 and low nd i 1 2 to 6 4 values by contrast the late miocene lavas have the lowest 87sr 86sr i 0 7030 0 7033 and the highest nd i 2 6 to 6 7 values geochemical features of these rocks indicate two episodes of enrichment processes during the evolution of the eocene early miocene volcanism in the biga peninsula the first stage source enrichment metasomatism occurred within the continental lithospheric mantle as a result of the previous subduction event s and produced a heterogeneously enriched source the second stage crustal contamination resulted from interaction between the metasomatized mantle derived melts and those magmas derived from the sakarya crustal basement during their ascent to the surface slab breakoff induced asthenospheric upwelling caused the melting of metasomatized mantle lithosphere beneath the sakarya continent and produced the middle eocene calc alkaline lavas geochemical isotopic and age relationships suggest increasing amounts of crustal contamination and a decreasing subduction signature during the evolution of magmas from the eocene through the early miocene crustal input was peaked during the early miocene volcanism coinciding with the exhumation and rapid uplift of the kazdag metamorphic massif asthenospheric upwelling beneath the kazdag core complex contributed to the generation of hybrid magmas formed from mixing of mantle and crustal melts during this stage the middle miocene 15 2 ma mildly alkaline rocks show less pronounced enrichment in lile and lree and display intermediate major and trace element compositions between the early miocene and late miocene lavas the cenozoic volcanism in biga peninsula waned briefly during 15 11 ma and was subsequently rejuvenated late miocene 11 0 0 4 8 32 0 19 ma producing mainly oib type alkaline lavas advanced extensional tectonics throughout nw anatolia in the late miocene led to upwelling of the asthenospheric mantle and its decompressional melting that collectively resulted in the eruption of short lived episodes of mainly oib type alkaline lavas this tectonomagmatic evolution of the cenozoic continental volcanism in western anatolia presents a well documented case study of an idealized post collisional magmatism in most orogenic belts around the world

the evolution of a porphyry cu au deposit based on la icp ms analysis of fluid inclusions bajo de la alumbrera argentina the chemical and physical evolution of magmatic to hydrothermal processes in the porphyry cu au deposit of bajo de la alumbrera northwestern argentina has been reconstructed with a quantitative fluid inclusion study fluid inclusion petrography microthermometry and single inclusion microanalysis by excimer laser ablation inductively coupled plasma mass spectrometry la icp ms are combined to determine the evolution of pressure temperature and ore metal concentrations including cu and au in the fluids complementary hydrogen and oxygen isotope analyses are used to further constrain the water sources in the evolving system the combined data provide a new level of insight into the mechanisms of metal sourcing and ore mineral precipitation in a porphyry style magmatic hydrothermal system based on previously reported observations of the igneous geology alteration geochemistry and veining history of the subvolcanic porphyries at alumbrera the distribution of fluid inclusion types in space and time is documented six major inclusion types are distinguished the highest temperature brine inclusions up to 750 c p 1 kbar are mainly recorded in barren quartz magnetite veins in the core of the alteration system these polyphase brine inclusions halite sylvite multiple opaque and transparent daughter crystals are interpreted as the most primitive magmatic fluid recorded at the level of the deposit they are of moderately high salinity 50 60 wt nacl equiv dominated by nacl kcl and fecl 2 and contain on average 0 33 wt percent cu and 0 55 ppm au upon cooling and decompression these saline liquids exsolve a vapor phase which is preferentially enriched in cu relative to its main salt components but probably plays a minor role in the formation of this particular deposit because of the inferred small mass fraction of vapor cooling and decompression from the highest initial p t conditions down to about 450 c causes magnetite k silicate alteration but no saturation in au or cu sulfides as recorded by continually high ore metal concentrations in the fluid inclusions coprecipitation of cu and au as chalcopyrite and native gold some early bornite occurs over a narrow range of decreasing fluid temperature with cooling from 400 to 305 c the cu concentration in the brine drops by about one order of magnitude to less than 0 07 wt percent without a proportional decrease in major salt components ore mineral precipitation extracts 85 percent of the cu and au from the fluid it is associated with potassic alteration as shown by a concomitant decrease in the k na ratio of the cooling magmatic brine and by an increase in its ba and sr concentrations elements which are probably liberated in the destruction of calcic igneous minerals the fluid chemical data demonstrate that the metal ratios in this and probably many other porphyry style ore deposits are primarily controlled by the magmatic source of the ore brines on the other hand the final hypogene ore grade of the deposit is controlled by the efficiency of ore mineral precipitation at alumbrera metal extraction is governed by the efficiency of cooling a high flux of magmatic fluid within a small rock volume dilution of residual magmatic fluids as recorded by aqueous fluid inclusions of decreasing salinities and temperatures below 295 c follows after the main stage of copper introduction and is associated with feldspar destructive phyllic alteration geometric relationships fluid analyses and stable isotope data together indicate that phyllic alteration results from postmineralization hydrothermal activity involving minor mixing between meteoric water residual brine and a waning input of magmatic vapor

origin and assembly of the tethyside orogenic collage at the expense of gondwana land abstract the tethysides are a superorogenic complex flanking the eurasian continent to the south and consisting of the cimmerides and alpides products of palaeo and neo tethys respectively we here review their evolution mainly on the basis of new maps showing the distribution of sutures magmatic rocks certain palaeobiogeographically and palaeoclimatologically significant taxa and facies and fragments of pan african 900 450 ma orogenic system forming the basement of many tethyside blocks these are supplemented by palaeomagnetic data reported in the literature a fundamental tenet of this paper is that major sutures which contain ophiolite fragments represent tectonic sections between continental blocks where oceanic crust has been subducted palaeo tethys came into existence largely in late carboniferous time coevally it began to be consumed by both internal and peripheral subduction zones which continued into the permian some of these had been inherited from pre tethyan times in the later permian rifting subparallel with the northern margin of gondwana land began between the zagros and malaysia separating a cimmerian continent from n gondwana land and thus heralding the opening of neo tethys and other smaller oceans that were back arc basins of palaeo tethys this rifting possibly also extended farther west into crete and mainland greece however the north china block yangtze block huanan block the eastern moity of the qangtang block north tibet and annamia all originally pieces of the end proterozoic early palaeozoic gondwana land had already separated from it in pre late carboniferous times possibly during the devonian all of these blocks and the cimmerian continent were characterized by cathaysian floral elements in late palaeozoic time palaeomagnetic and palaeontological data showing the original gondwana land affinity of these continental blocks are supplemented by correlating late proterozoic early palaeozoic pan african sutures orogenic belts and sedimentary basin fragments across tethyside sutures late permian foraminiferal provinces are related to this palaeogeographical interpretation by triassic times most cimmeride subduction zones were already in existence the cimmerian continent accelerated its separation from gondwana land and locally in the late permian began disintegrating internally along the waser rushan pshart banggong co nu jiang mandalay ocean by late triassic time all of the chinese blocks except lhasa and annamia had collided with each other and with laurasia the resulting enormous orogenic collage had a soft cushion between itself and laurasia in the form of the enormous accretionary complex of the songpan ganzi this connection enabled laurasian land vertebrates to reach south east asia by late triassic time in late triassic to middle jurassic times most major cimmeride collisions were completed widespread aridity in central asia occurred in late jurassic time probably in the rain shadow of the newly formed cimmeride mountain wall neo tethyan subduction systems formed along the s margin of the cimmerides or within neo tethyan oceanic lithosphere during the jurassic most if not all were north or east dipping they continued the northerly migration of the tethyside blocks evolution of the tethysides influenced the distribution of marine and terrestrial organisms and affected sea level changes and patterns of atmospheric circulation during much of the mesozoic and cainozoic it is likely to have reflected the surface expression of a persistent trend in the large scale convective circulation in the mantle that continuously transported material northward into the tethyan domain

post collision magmatism and tectonics in northwest anatolia a suite of biotite hornblende granodiorite intrusions has been emplaced into blueschist facies metasediments in northwest anatolia following collision between two continental margins now represented by the tavsanli and sakarya zones the 40ar 39ar ages of phengites and glaucophanes from the blueschists metamorphosed under unusually high p low t conditions p 20 2 kbar t 430 30 c suggest that metamorphism apparently occurred over a period spanning at least 20 ma from 108 to 88 ma post tectonic granodiorites were emplaced during the eocene 53 to 48 ma resulting in a cordierite and andalusite bearing thermal aureole indicative of pressures of 3 kbar trace element systematics of the granodiorites are consistent with a derivation either from mantle derived magmas by fractional crystallisation in shallow magma chambers or from anatexis of crustal lithologies of internediate composition at pressures 10 kbar the preservation of high p low t assemblages in the blueschists together with the range of ages determined for blueschist facies metamorphism are indicative of rapid exhumation of delaminated fragments from a subducted continental margin however decompression melting of the crust is unlikely to have been a significant cause of magmatism both because exhumation of the blueschists from deep crustal levels predated magmatism by at least 25 ma and because of the small melt fraction 0 1 that may be generated in crustal lithologies by this process melting in the mantle wedge is required either to generate a primary melt for the derivation of magmas of intermediate composition or to provide an advective heat source for crustal melting the cause of melt formation in the upper mantle may be related to the termination of subduction following collision during the mid eocene

endostromatolites from permafrost karst yukon canada paleoclimatic proxies for the holocene hypsithermal a remarkable biogenic calcite precipitate forms carpets of finely laminated 1 mm diameter columns lining fissures within limestone bedrock in the permafrost regions of the northern yukon this material endostromatolite for its laminated morphology and growth hidden within the carbonate rock is ubiquitous within limestone terrains of the arctic and grew during the early holocene hypsithermal dissolution on the interior fissure faces is accompanied by biomineralization of the opposing faces a previously unrecognized weathering process in permafrost regions occurrence is restricted to outcrops with a southern orientation in permafrost regions in this case from the ogilvie mountains northern yukon growth occurs in water saturated talik during periods of permafrost degradation during insolation maxima their enriched 13c values 1 7 to 11 4 are generated in a methanogenic environment during anaerobic degradation of soil derived organic carbon a paleotemperature signal extracted from the 18o

late devonian carbon isotope stratigraphy and sea level fluctuations canning basin western australia the upper devonian reef complexes of the canning basin contain some of the world s best exposed continuous stratigraphic sections through the frasnian famennian boundary the facies distribution and composition of these reef complexes record interactions among sea level changes sediment supply ocean chemistry and paleoecology changes in relative sea level produced spatial shifts in reef platform development and regional changes in sediment supply that can be correlated across facies boundaries using a combination of sequence stratigraphy biostratigraphy and carbon isotope stratigraphy during the lowstand interval below the frasnian famennian boundary the reef margin advanced down the reef slope in shallow water environments and siliciclastics locally dominated in the marginal slope environment compilation of a broad late frasnian to early famennian sequence stratigraphic framework for the canning basin demonstrates that transgressive intervals correlate to positive carbon isotopic excursions within the basin these isotopic shifts also can be correlated to time equivalent positive carbon isotopic excursions reported from transgressive intervals in europe thus the late frasnian transgressions in the canning basin were primarily eustatic rather than tectonic in origin and positive carbon isotopic signatures of the kellwasser horizons are globally correlative c 2002 elsevier science b v all rights reserved

location of the western pontides nw turkey during triassic time preliminary palaeomagnetic results summary this paper reports preliminary results of palaeomagnetic data obtained from the lower triassic schtian and mid triassic anisian rocks in the western pontides nw turkey the triassic rocks have been studied by applying thermal and or alternating field demagnetization the characteristic magnetization has a 50d mean inclination derived from 41 samples taken from three separate sites although the inclination values for the three sites are similar the corresponding declination angles indicate that the gumusdere site which lies to the north of istanbul city has undergone 68d anticlockwise rotation while the tavsancil and denizlikoy sites which are to the southeast of istanbul have rotated 40d clockwise on average the mean inclination 50d places the western pontides at the southern margin of laurasia during lower and mid triassic time

late cenozoic volcanic evolution of the northeastern aegean region abstract late cenozoic volcanism occurred in an extensional tectonic regime in the northeastern aegean activity commenced in northeastern greece during the early oligocene and in northwestern turkey during the late oligocene early miocene the beginning of activity was characterized by calc alkaline intermediate acid volcanism however alkaline intermediate basic volcanism became dominant from the late miocene until the pleistocene this change in nature of volcanism is not related to a change of regional tectonic regime as previously thought instead we propose that the volcanic evolution reflects an increasing asthenospheric contribution facilitated by a thinned extended lithosphere arising from the regional extensional tectonics

jurassic cretaceous paleomagnetism and paleogeography of the pontides turkey published paleomagnetic data from the pontides indicate anomalously low jurassic and early cretaceous paleolatitudes compatible with the southern neo tethyan african continental margin and significantly different from paleolatitudes predicted for the northern eurasian neo tethyan margin we present a new set of paleomagnetic data from 50 late cretaceous sites mainly from the western pontides and from the eastern pontides and 11 early jurassic sites mainly from the eastern pontides fold tests indicate that the characteristic magnetization components predate eocene folding late cretaceous site mean declinations are northerly in the eastern pontides and rotated to the west by a few tens of degrees in the western pontides late cretaceous site mean declinations are affected by local clockwise rotation in one sampling region close to the north anatolian fault the mean late cretaceous inclinations and resulting paleolatitudes are 41 1 23 5 n and 43 7 25 5 n for the western and eastern pontides respectively for the eastern pontides the early jurassic liassic mean inclination is 60 5 yielding a paleolatitude of 41 4 n considerably further north than previous paleolatitude estimates for the eastern pontides at this time the paleolatitude estimates for the western and eastern pontides are consistent with these units being close to the eurasian continental margin during liassic and late cretaceous time

micro morphological inorganic organic isotope geochemisty and microbial populations in endostromatolites cf fissure calcretes haughton impact structure devon island canada the influence of geochemical pathways on the preservation of isotope biomarkers abstract endostromatolites cf fissure calcretes which possess microbial evidence for a biogenic origin are also thought to preserve isotopic biosignatures in this study a multi proxy approach combining micro morphological geochemical and isotopic analyses of middle holocene age endostromatolites within sub horizontal fissures in dolomitic limestone outcrops in the haughton impact crater region devon island nu was used to determine their origin abiotic versus biogenic and to identify potential isotope biosignatures the micro morphologies of the endostromatolites revealed some structures typical of a physico chemical origin whereas the presence of rod shape particles and filamentous structures was more reminiscent of biologically induced forms the endostromatolites have 13 c and 18 o compositions reaching maximum values of 7 2 and 11 2 respectively positive relations between the elemental mg sr and isotopic 18 o and 13 c composition of the endostromatolites are indicative of an evaporative enrichment process of the meteoric water infiltrating the fissures prior to calcite precipitation however the positive 13 c toc 13 c caco3 relation in the endostromatolites is strongly indicative that they were microbially mediated in support of a microbial origin mostly aerobic heterotrophic bacteria that have been linked to both carbonate dissolution and mineralization were observed in the microbial diversity of the endostromatolites however the results are inconclusive to attribute the formation of the endostromatolites solely to a biologically induced mineralization but instead favor a more complex origin that involved abiotic evaporation and to some extent biological processes prior to and during calcite precipitation considering that the endostromatolites result from microbially influenced mineralization the effects of physico chemical processes on the geochemical and isotopic composition of the endostromatolites were much greater than the effect of the biological processes thus it seems that preservation of isotopic biosignatures in secondary carbonate precipitates is dependent on the sequence of processes generating chemical and isotopic modifications of the solution prior to calcite precipitation the mechanism and condition equilibrium or kinetic of formation and post fossilization alteration processes

implications of jurassic chert identified in the tokat complex northern turkey the tokat complex is a strongly deformed tectono sedimentary mixture of low grade metamorphic rocks with abundant recrystallized limestone and relatively rare serpentinite and radiolarian chert in blocks of variable size samples from the radiolarian chert blocks found in highly crushed zones each of which corresponds to a thrust sheet within an imbricate thrust zone have yielded a tithonian fossil assemblage they are interpreted as tectonic inclusions emplaced within the tokat complex after its main post early permian pre liassic metamorphism and were derived from the rifting and opening of a neotethyan ocean the presence of tithonian blocks within low grade metamorphic rocks of the tokat complex shows that tethys ocean was in existence in this region by latest jurassic time we also suggest that the presence of ophiolitic slices imbricated with the pontide basement tokat complex explains the swarm of north anatolian fault zone nafz splays in this region where the nafz likely followed a major pre existing crustal weakness

palaeomagnetic evidence for substantial rotation of the almacik flake within the north anatolian fault zone nw turkey summary palaeomagnetic data on eocene rocks from within the almacik flake bounded by two strands of the north anatolian right lateral fault indicate that the flake has undergone an apparent counterclockwise rotation of about 148 on average we interpret this as a real 212 clockwise rotation because the almacik flake is entirely delimited by the right lateral north anatolian fault strands the only dominant post eocene structure in the area and because areas surrounding the flake do not show the same rotation this rotation must have occurred since the north anatolian fault originated in the late medial miocene late serravallian 11 5 ma and if so may imply either a larger total slip along it than hitherto estimated or that the almacik flake is the surface expression of a flower structure rotating above a shear zone narrower than the present width of the flake

formation of the late palaeozoic early mesozoic karakaya complex and related ophiolites in nw turkey by palaeotethyan subduction accretion several pre jurassic tectonic units in nw turkey are crucial to the current debate regarding the timing and direction of subduction of palaeotethys a major ocean that separated eurasia and gondwana in late palaeozoic early mesozoic times the most critical unit is the karakaya complex a deformed low grade assemblage of oceanic origin which comprises a nw verging se dipping stack of tectonostratigraphic units here interpreted as a palaeotethyan accretionary complex the units display lithologies consistent with origins in seamount trench abyssal and rifted carbonate platform settings clastic basin sequences developed on top of the complex other relevant tectonostratigraphic units in the area include ultrabasic rocks of supra subduction zone affinity which tectonically overlie permian carbonate platform units with intervening metamorphic soles and melanges restored structural trends suggest the presence of a southward dipping palaeotethyan subduction zone bordering gondwana related units during the late permian triassic this was probably additional to more important regional northward subduction along the southern margin of eurasia from the eastern mediterranean to the himalayas

calculation of oxygen isotope fractionation in hydroxyl bearing silicates abstract the modified increment method has been applied to the calculation of oxygen isotope fractionation factors for hydroxyl bearing silicate minerals the order of 18o enrichment obtained in common rock forming minerals is pyrophyllite kaolinite tourmaline talc prehnite topaz illite phengite lepidolite muscovite staurolite epidote glaucophane serpentine chlorite tremolite hornblende phlogopite biotite humite norbergite ilvaite hydroxyl bearing silicates are enriched in 18o relative to hydroxyl groups but depleted in 18o relative to anhydrous counterparts three sets of self consistent fractionation factors between quartz and the hydroxyl bearing silicate minerals between calcite and the silicate minerals and between the silicate minerals and water have been calculated for a temperature range of 0 1200 c the fractionation factors calculated for mineral pairs are applicable to isotopic geothermometry in igneous metamorphic and sedimentary petrology they can be used as a test of isotopic equilibrium or disequilibrium in natural mineral assemblages over all temperature ranges of geological interest the difference in oxygen isotope composition between the hydroxyl bearing mineral and the oh group is quantitatively demonstrated to be temperature dependent and therefore can be used as a single mineral geothermometer

possible microbial effects on stable carbon isotopes in hot spring travertines recent and older early holocene to pleistocene hot spring travertine carbonates from central italy have two distinctive macrofabrics crystalline crusts and shrubs crystalline crusts are laminated slope deposits that formed abiotically following co 2 degassing from spring water the formation of shrub travertine irregular dendritic precipitates from pool environments is controversial and has been attributed to both abiotic and microbial processes oxygen isotope variation in our travertines can be explained by abiotic processes mainly co 2 degassing in contrast our carbon isotope data cannot be wholly explained by abiotic co 2 degassing invoked in earlier studies because photosynthesis is known to preferentially remove 12 c leaving ambient waters enriched in 13 c this fractionation should be recorded in delta 13 c values of microbially influenced travertine our shrub carbon isotope values are between 0 5 per thousand and 6 0 per thousand larger than values for associated abiotic precipitates and this difference is probably caused by microbial activity these isotope data support previous visual evidence that some shrub fabrics are microbially influenced

palaeo climate reconstruction from stable isotope variations in speleothems a review abstract speleothems are now regarded as valuable archives of climatic conditions on the continents offering a number of advantages relative to other continental climate proxy recorders such as lake sediments and peat cores they are ideal materials for precise u series dating yielding ages in calendar years thereby circumventing the radiocarbon calibration problems associated with most other continental records stable isotope studies in speleothems have shifted away from attempting to provide palaeo temperature reconstructions to the attainable goal of providing precise estimates for the timing and duration of major o isotope defined climatic events characterised by high signal to noise ratios e g glacial interglacial transitions dansgaard oeschger oscillations the 8200 year event unlike the marine records speleothem data sets are not tuned and their independent chronology offers opportunities to critically assess leads and lags in the climate system that in turn can provide important insights into forcing and feedback mechanisms improved procedures for the extraction and measurement of stable isotope ratios in fluid inclusions trapped in speleothems are likely to provide in the near future a much enhanced basis for the quantitative interpretation of o isotope ratios in speleothem calcite the latter developments open up once again the tantalising prospect of palaeo temperature estimates but more importantly perhaps provide a direct test for a new generation of general circulation models whose hydrological cycles will incorporate the water isotopes the literature is reviewed briefly to provide for the reader a sense of the current state of the art and to provide some pointers for future research directions

a case of obduction related high pressure low temperature metamorphism in upper crustal nappes arabian continental margin oman p t paths and kinematic interpretation in the southeastern oman mountains the saih hatat tectonic window reveals arabian continental material beneath the oceanic sensu lato nappes i e the hawasina sedimentary units and the huge sumail ophiolite the northeastern internal half of the window suffered an intense deformation associated with a high pressure low temperature hp lt metamorphism approximately dated at 80 75 ma according to the available stratigraphie data after the deformation due to the absence of collision the obduction inherited structural and metamorphic pattern was virtually unmodified a metamorphic map is established based on mineral assemblages in metapelites and metabasites low grade assemblages occur in the highest units muscat nappes quryat unit characteristic minerals are femg carpholite lawsonite associated with kaolinite or pyrophyllite and locally sudoite in the metapelites while lawsonite and blue amphiboles are found in the metabasites high grade rocks outcrop in the deepest and easternmost units as sifah antiform and are typified by an epidote glaucophane bearing eclogite assemblage intermediate units hulw show assemblages of intermediate grade chloritoid schists and glaucophane bearing metabasites higher grade assemblages such as talc chloritoid were not found inverted gradients are observed locally in the muscat nappes pyrophyllitebearing units above kaolinite quartz bearing units and these are ascribed to late metamorphic thrust displacements which are demonstrated by microstructures a complex p t evolution is fairly well documented by the mineral assemblages prograde evolution in the subophiolitic continental rocks began with a rather hot gradient of about 30 35 c km with chloritoid growth in the higher units thereafter pressure increased with the temperature remaining constant or even decreasing chloritoid replaced by kaolinite oxides and carpholite growth in synkinematic conditions the peak p t conditions are close to 8 kbar 270 c for the muscat nappes and 11 kbar 400 c for the as sifah unit the corresponding surface related gradient is low 10 15 c km during the retrograde evolution pressure and temperature generally decreased concomitantly but in some of the upper units temperature remained constant or increased slightly for some time at which point sudoite growth from carpholite took place the metamorphic pattern and mineral evolution are interpreted in the framework of the late cretaceous obduction the already cold oceanic lithosphere was thrust upon a relatively hot thinned passive margin with coeval basaltic volcanism pressure progressively increased in the passive margin due to the wedge shape of the advancing ophiolite the maximum thickness of which was about 25 km in the as sifah area in this area the overburden was also attributable to the accumulation of continental material up to 5 km thick by means of a complex set of synmetamorphic often conjugated folds and thrusts the basal peridotites of the obducted slab were probably not hotter than 300 c during its thrusting upon the continental margin the temperature of the tectonic pile below the ophiolite remained low because it was thrust above more external and still colder continental areas late thrusting in the same southerly direction controlled the retrograde evolution together with erosional and gravity driven tectonic unloading

evolution of the bayramic magmatic complex northwestern anatolia abstract during the oligocene middle miocene period widespread magmatic activity developed in western anatolia following the continental collision between the sakarya continent and the tauride anatolide platform this produced both intrusive and extrusive rocks which appear to be associated in space and time as exemplified from the bayramic area in the bayramic area the magmatic activity started with the intrusion of the evciler granite and the coeval lower volcanic association this was followed by the development of the upper volcanic association these rock groups form collectively the bayramic magmatic complex which was generated under an on going north south compressional regime the bayramic magmatic complex has a subalkaline composition displaying a calcalkaline trend trace elements and ree contents resemble to island arc and collision related magmas according to the isotope values the bayramic magmatic complex was derived from the magmas of lithospheric mantle origin which were later contaminated while passing through the thick continental crust in a post collisional tectonic setting during the oligocene early miocene period the latest product of the magmatism is the late miocene pliocene basalt lavas their geochemical properties are clearly different from the oligocene early miocene magmatic rocks the basalts were generated when the north south compression gave way to the north south extensional regime

environmental setting micro morphologies and stable c o isotope composition of cold climate carbonate precipitates a review and evaluation of their potential as paleoclimatic proxies abstract given the growing interest in carbonate deposits from polar regions as paleoclimatic proxies this review paper first provides a classification of the various types of cold climate carbonate precipitates followed by a summary of the 13 c and 18 o composition of the carbonate deposits and parent water from which the carbonates precipitated the cold climate carbonate precipitates were classified into three broad categories powders crusts and speleothem the carbonate powders include those that precipitated in relation to aufeis aggradation cryogenic aufeis calcite and in relation to the growth of various annual perennial ice formations in freezing caves cryptocrystalline calcite and calcite pearls the carbonate crusts can be further subdivided based on their lithic environment those that precipitated on the upper surface of bedrock clasts i e subglacially precipitated calcite and evaporative calcite crusts those that are located on the underside of clasts i e pedogenic carbonates and those that precipitated in rock outcrop fissures i e endostromatolites the cold climate carbonate precipitates have a highly variable isotopic composition with 18 o values ranging between 6 5 and 28 vsmow and 13 c values in the 10 20 vpdb range however each type of carbonate precipitates has a specific 13 c and 18 o range suggesting that their environmental setting and the mechanism by which they formed controls their 13 c and 18 o signature it was found that carbonate deposits that precipitated under equilibrium physico chemical conditions had a 13 c value that is in equilibrium with that of the parent water while its 18 o composition was more variable as it is in part controlled by the temperature of reaction and by the 18 o and calcite saturation state of the parent water by contrast the 18 o composition of biologically precipitated carbonate deposits endostromatolites reflect that of the parent water while its 13 c composition was enriched over that of the parent water due to bacterial methanogenesis in the case of kinetically precipitated carbonate deposits the 18 o and 13 c values are out of equilibrium relative to that of the parent water due to the faster rate of reaction

stratigraphic and structural development of the eastern pontides turkey this paper describes the stratigraphic and structural development of the eastern pontides north turkey based on section logging at eight localities construction of three structural profiles across the mountains and published literature the eastern pontides comprise a late carboniferous to miocene sequence resting on a basement of hercynian metamorphics late carboniferous to scythian sediments are continental clastics interpreted as having been deposited in an extensional half graben the middle triassic is limestone reflecting the development of a south facing passive margin in the late triassic the ocean palaeotethys began to close flysch was deposited in most places with minor shallow water limestones in the sinemurian above an inverted half graben all pre aalenian strata were deformed during the cimmerian orogeny after a phase of subduction related volcanism in the mid jurassic limestones were deposited during the late jurassic and early cretaceous mainly in shallow water the aptian and albian are absent due to doming in the western pontides prior to the opening of the western black sea but there is a thick sequence of upper cretaceous arc volcanic rocks and intervening turbidites the upper palaeocene is absent possibly due to rifting in the eastern black sea major compression affected the pontides from the eocene to the pliocene associated with the closure of the tethyan ocean oligocene and younger rocks are accordingly non marine

exhumation of blueschists along a tethyan suture in northwest turkey a blueschist belt formed during the mid cretaceous 88 ma high pressure metamorphism of a passive continental margin sequence of shale siltstone quartzite and limestone occurs immediately south of the tethyan suture in northwest turkey a transect across the tethyan suture was mapped to constrain the exhumation of blueschist facies assemblages the presence of jadeite glaucophane and lawsonite in the blueschists indicates p t conditions of 20 kbar and 430 c the blueschists are tectonically overlain by a cretaceous oceanic accretionary complex showing an incipient blueschist metamorphism a peridotite slab with subvertical layering lies along a low angle fault contact over the blueschists and the accretionary complex isolated slices of early cretaceous 101 4 ma garnet amphibolites occur at the base of the peridotite the garnet amphibolites which show an incipient blueschist facies overprint have probably formed during the oceanic subduction in the foot wall of the subduction zone and later underplated the hanging wall blueschists and peridotites are abruptly truncated in the north by the steeply dipping suture fault that juxtaposes unmetamorphosed and slightly deformed triassic to jurassic sediments of the northern continent against the peridotite and the accretionary complex tectonic juxtaposition of the lower pressure accretionary complex and peridotites over the higher pressure blueschists implies the removal of a 45 km thick oceanic mantle sequence above the blueschists regional geological and geometric constraints suggest that the exhumation of the blueschists was achieved by a combination of two simultaneously acting mechanisms the first was the detachment of the upper crustal blueschist sequence from its basement in the subduction zone and its incorporation to the hanging wall followed by buoyant ascent the second mechanism is the progressive shallowing of the subducted continental lithosphere resulting in the thinning of the mantle wedge above the subducted slab the blueschists were partly exposed prior to the paleocene continent continent collision post collisional eocene 52 48 ma calc alkaline plutons that were emplaced in the blueschists and the overlying peridotite at 10 km depth are interpreted to have formed by crustal anatexis from advective heating by mantle melts these have probably been generated during the upwelling of the asthenosphere under the shallowing continental lithosphere

age of initiation of collision between india and asia a review of stratigraphic data abstract the collision of india with asia is perhaps the most profound tectonic event to have occurred in past 100 ma it is responsible for the uplift of the himalayas and tibetan plateau and has been argued to have been responsible for geological geochemical and climatological consequences of global extent yet the age of initiation of this collision remains poorly constrained the literature is replete with estimates that range from the late cretaceous 65 ma to latest eocene

tectonic significance of synextensional ductile shear zones within the early miocene alacamdag granites northwestern turkey synextensional granitoids may have significant structural features leading to the understanding of the evolution of extended orogenic belts one of the highly extended regions the aegean region includes a number of metamorphic core complexes and synextensional granitoids that developed following the alpine collisional events the alacamdag area in northwestern turkey is one of the key areas where miocene granites crop out along the boundary of various tectonic units structural data from the early miocene alacamdag granites demonstrated two different deformation patterns that may provide insights into the development of granitic intrusions and metamorphic core complexes 1 steeply dipping ductile shear zones caused emplacement of syn tectonic granite stocks they include kinematic indicators of a sinistral top to the sw displacement this zone has also juxtaposed the izmir ankara zone and the menderes massif in the west and east respectively 2 gently dipping ductile shear zones have developed within the granitic stocks that intruded the schists of the menderes massif on the structurally lower parts kinematic data from the foliated granites indicate a top to the ne displacement which can be correlated with the direction of the hanging wall movement documented from the simav and kazdag metamorphic core complexes the gently dipping shear zones indicate the presence of a detachment fault between the menderes massif and the structurally overlying izmir ankara zone mesoscopic to map scale folds in the shallow dipping shear zones of the alacamdag area were interpreted to have been caused by coupling between ne sw stretching and the accompanying nw se shortening of ductilely deformed crust during early miocene times one of the ne trending shear zones fed by granitic magmas was interpreted to form the northeastern part of a sinistral wrench corridor which caused differential stretching between the cycladic and the menderes massifs this crustal scale wrench corridor the izmir balikesir transfer zone may have controlled the asymmetrical and symmetrical extensions in the orogenic domains the combination of the retreat of the aegean subduction zone and the lateral slab segmentation leading to the sinistral oblique slip tearing within the eurasian upper plate appears to be a plausible mechanism for the development of such extensive ne trending shear zones in the aegean region

isotope geochemistry of caliche developed on basalt enormous variations in oxygen and carbon isotopes occur in caliche developed on 3 ma basalts in 3 volcanic fields in arizona significantly extending the range of 18o and 13c observed in terrestrial caliche within each volcanic field 18o is broadly co variant with 13c and increases as 13c increases the most 18o and 13c enriched samples are for subaerial calcite developed on pinnacles knobs and flow lobes that protrude above tephra and soil the most 18o and 13c depleted samples are for pedogenic carbonate developed in soil atmospheres the pedogenic caliche has 18o fixed by normal precipitation in local meteoric waters at ambient temperatures and has low 13c characteristic of microbial soil co2 subaerial caliche has formed from 18o rich evapoconcentrated meteoric waters that dried out on surfaces after local rains the associated 13c enrichment is due either to removal of 12c by photosynthesizers in the evaporating drops or to kinetic isotope effects associated with evaporation caliche on basalt lava flows thus initially forms with the isotopic signature of evaporation and is subsequently over layered during burial by calcite carrying the isotopic signature of the soil environment the large change in carbon isotope composition in subsequent soil calcite defines an isotopic biosignature that should have developed in martian examples if mars had a warm wet early period and photosynthesizing microbes were present in the early soils the approach can be similarly applied to terrestrial precambrian paleocaliche in the search for the earliest record of life on land large variations reported for 18o of carbonate in martian meteorite alh84001 do not necessarily require high temperatures playa lakes or flood runoff if the carbonate is an example of altered martian caliche

stable isotopic constraints on fluid rock interaction and cu pge s redistribution in the sonju lake intrusion minnesota the sonju lake intrusion part of the 1 1 ga midcontinent rift related beaver bay complex is a 1 200 m thick strongly differentiated layered sequence of mafic cumulates located in northeastern minnesota basal melatroctolite and dunite layers are overlain by troctolite gabbro fe ti oxide rich gabbro apatite diorite and monzodiorite stratigraphic intervals rich in pt pd cu and s occur over 500 m in the fe ti oxide rich gabbro and apatite diorite units peak concentrations show offsets that are similar to those found in other tholeiitic layered intrusions concentrations of pd in excess of 100 ppb are confined to the lowermost 25 m of the interval copper shows a sharp increase to 630 ppm above the pd rich interval sulfur contents are low 375 ppm in the cu rich interval but they increase to values as high as 3 150 ppm above in the apatite diorite disseminated sulfides in the intrusion have 34s values that range from 2 2 to 3 per mil vienna canyon diablo troilite v cdt and suggest that contamination by country rock sulfur was not an important process in the formation of the metal rich interval 18o values of plagioclase from the intrusion range from 5 6 to 12 0 per mil v smow and indicate that a relatively low 18o fluid 18o 3 5 interacted with the rocks of the intrusion at temperatures less than 275 c clinopyroxene and fe ti oxides ilmenite with minor amounts of titanomagnetite show much more restricted ranges in 18o values 4 6 5 7 and 5 5 6 7 per mil respectively and attest to the kinetic control of the oxygen isotope exchange process the externally derived fluid that interacted with rocks now enriched in platinum group elements pge cu and fe sulfide minerals locally liberated sulfur and replaced chalcopyrite and pyrite with goethite in the cu rich zone goethite that replaces chalcopyrite may contain up to 8 5 weight percent cu it is evident that hydrothermal alteration resulted in a decoupling of copper and sulfur with sulfur being transferred out of the cu rich interval interaction between rocks in the pge cu s interval of the sonju lake intrusion and an externally derived fluid at low temperatures modified what appears to have been a primary stratigraphic metal sulfur zonation the effects of hydrothermal alteration on pge and base metal sulfide mobility and redistribution must be understood before models of primary zonation processes can be meaningfully applied

the biogenic origin of needle fibre calcite needle fibre calcite is one of the most ubiquitous habits of calcite in vadose environments caves deposits soil pores etc its origin either through inorganic indirect or direct biological processes has long been debated in this study investigations at 11 sites in europe africa and central america support arguments for its biogenic origin the wide range of needle morphologies is the result of a gradual evolution of the simplest type a rod this rod is the elementary brick which by aggregation and welding builds more complex needles the absence of cross welded needles implies that they are welded in a mould or under a longitudinal and unidirectional constraint before being released inside the soil pores the difference between the lengthening of the needles and the c axis can be explained by the existence of needles observed under a scanning electron microscope in organic sleeves which can act as a mould during rod growth complex morphologies with epitaxial outgrowths on straight rods cannot have grown entirely inside organic microtubes they must result from soil diagenesis after the release of straight rods in a soil free medium whisker crystals are interpreted as the result of growth and coalescence of euhedral crystals on a rod rhomb chains are considered to be the consequence of successive epitaxial growth steps on a needle during variations in growth conditions isotopic signatures for needle fibre calcite vary from 16 63 to 1 10 and from 8 63 to 2 25 for 13c and 18o respectively the absence of high 18o values for needle fibre calcite precludes a purely physicochemical origin evaporative for this particular habit of calcite as epitaxial growth cannot precipitate in the same conditions as initial needles needle fibre calcite stable isotopic signatures should be used with caution as a proxy for palaeoenvironmental reconstructions in addition it is suggested that the term needle fibre calcite should be kept for the original biogenic form the other habit should be referred to as epitaxial forms of needle fibre calcite

the association of gold with calcrete abstract the discovery that au accumulates in calcrete pedogenic carbonate or caliche was made in 1987 by csiro calcrete is a general term describing accumulation of alkaline earth metals in soils of arid and semi arid terrains around the world the principal constituent of calcrete is calcite while au is a noble metal calcrete has been a significant tool in a number of au deposit discoveries so understanding the mechanisms by which these diametrically different components come together is valuable for enhancing future discovery numerous laboratory experiments case histories and exploration models have been published most from australia yet we do not fully understand the mechanisms involved it is timely therefore twenty five years on since the first publication of this phenomenon to review this highly unusual but economically important association critical to any review on au in calcrete is to first consider calcretes themselves the nature of a particular calcrete where it has formed and mode of formation is relevant to how where and why au accumulates within it this review commences with a background nomenclature history classification and some examples of calcrete types found near au deposits how calcretes form their origins and the role of biota is considered their locations in the regolith and landscape as well as exploration models for au in calcrete are discussed a section on the chemistry of au in calcretes details what we know about possible mechanisms of formation and considers what laboratory experiments on microorganisms and abiotic experiments tell us following on is a summary of practical aspects of identifying collecting and analysing samples for exploration purposes selected mineral exploration case histories are described and how they fit into models of exploration and different regolith settings concluding sections include a summary and implications of this accumulated knowledge to discovering au deposits

geology of the ignimbrites and the associated volcano plutonic complex of the ezine area northwestern anatolia abstract the ezine region is located in the northwestern part of anatolia where young granitic and volcanic rocks are widespread and show close spatial and temporal association in this region magmatism began with the kestanbol granite which intruded into metamorphic basement rocks and formed contact metamorphic aureole to the east and southeast the pluton is surrounded by hypabyssal rocks which in turn are surrounded by volcanic associations the volcanic rocks may be divided into two main groups on the basis of their lithological properties lavas and lahar deposits dominate the northern sector while ignimbrites dominate the southern sector the ignimbrite eruptions were formed partly coevally with the plutonic and the associated volcanic rocks during the early miocene they appear to have been associated in a caldera collapse environment geochemical properties of the plutonic and the associated volcanic assemblages indicate that the magmas are hybrid and co genetic and were formed from a similar mantle source under a compressional regime prior to the opening of the present e w trending graben of the aegean western anatolian region

s o and pb isotopic evidence on the origin of the inkaya simav kutahya cu pb zn ag prospect nw turkey abstract the inkaya cu pb zn ag prospect is a typical example of the hydrothermal mineralization occurring in the menderes massif which crop out in western anatolia the prospect located approximately 20 km west of simav kutahya turkey in northern part of the menderes massif have been characterized through the detailed examinations involving geological mineralogical whole rock geochemistry fluid inclusion stable isotope and lead isotope the inkaya cu pb zn ag prospect is located along an e w trending fault in the cambrian simav metamorphics which consist of quartz muscovite schist quartz biotite schist muscovite schist biotite schist and the arikayasi formation which is composed of marbles galena sphalerite chalcopyrite pyrite and fahlore are the main minerals and they are accompanied by small amounts of cerussite anglesite digenite enargite chalcocite covellite bornite and fe oxides with gangue quartz in addition to pb zn cu ag the ore samples contain substantial quantities of as cd and bi and small amount of au average contents of cu pb zn and ag are 77 400 ppm 102 600 ppm 6843 ppm and 203 ppm respectively the 34s values for galena chalcopyrite and pyrite formed in the same stage vary in the range from 1 7 to 2 1 average 2 0 0 1 to 0 3 average 0 2 and 1 5 to 2 6 average 1 5 respectively 34s values for h2s representing the composition of the fluids responsible for the sulfide mineral formations and calculated from the 34s value are between 2 77 and 1 33 it is consistent with the sulfur in sulfide minerals 18oquartz values range from 11 3 to 16 4 and estimated 18ofluid values range from 5 4 to 10 6 pyrite galena and pyrite chalcopyrite pairs calculated to determine equilibrium isotope temperatures based on 34s values are between 254 6 and 277 4 c for pyrite galena and 274 7 c for pyrite chalcopyrite sulfur and oxygen isotope values similar to the values for fluid equilibrated with an felsic magmatic source fluid inclusion studies on quartz of the same silicification stage coexisting with galena sphalerite and chalcopyrite collected from the mineralized vein indicate that the temperature range of the fluids is 235 c to 340 c and that the salinities are 0 7 to 4 49 wt nacl equivalent the wide range of homogenization temperatures and relatively lower salinities of the fluid inclusions indicate that at least two different fluid generations were trapped in the quartz from only one fluid type also lower salinities of fluid inclusion probably indicate mixing of meteoric water and magmatic fluid the galena has 206pb 204pb values of 18 862 18 865 207pb 204pb values of 15 707 15 711 and 208pb 204pb values of 39 033 39 042 the lead isotope values show a similarity with upper crustal values

the candelaria cu fe au and punta del cobre cu fe deposits copiapo chile a case for extension related granitoid emplacement and mineralization processes the lower cretaceous volcanic formations of copiapo chile host major stratiform disseminated vein and stockwork mineral deposits among these are the punta del cobre district cu fe and the neighbouring large candelaria deposit cu fe au these deposits are likely to have formed during a major extensional event that was accompanied by granitoid emplacement that triggered important contact metamorphism metasomatic activity and mineralization processes we suggest here that alteration mineralization processes developed within the upper plate domain of a nne trending ese dipping extensional system while granitoids were accomodated within the lower plate if this model prove to be right candelaria type deposits may be hidden beneath the present higher structural position of the punta del cobre district