using fractal crustal magnetization models in magnetic interpretation1 evidence from borehole susceptibility logs and the spectral analysis of aeromagnetic data suggests that the three dimensional distribution of magnetization within the crust can be described as fractal this property can be exploited in magnetic interpretation methods which explicitly require statistical information on the spatial variation of magnetization specifically we address the problem of magnetic source depth estimation through downward continuation and gridding aeromagnetic survey data using the method of kriging when magnetic data are continued downwards the depth at which the power spectrum flattens out the white depth can be taken to be an estimate of the top of the source distribution this procedure assumes that individual sources are uncorrelated with each other taking into account the correlation of the magnetization using a fractal description leads to a reduction in this depth estimate gridding of randomly distributed magnetic measurements using kriging requires an estimate of the covariance of the data compared with the assumption of a white uncorrelated magnetization distribution using fractal covariances for kriging produces gridded estimates which more closely reflect the statistics of the underlying magnetization process and produce maps with a justifiable degree of smoothness

deep structures underneath the sihong segment of the tan lu fault zone eastern china interpretations of gravity anomaly and seismic profiles abstract the sihong segment of the tan lu fault zone sstlfz is located in the sihong county of the jiangsu province and composed of 5 branches which are mainly buried faults the tan lu fault zone is characterized by segmentation and its regional distribution deep structures and geodynamic evolution in the sihong area remains controversial we provided evidence of gravity anomaly and seismic reflection profiles suggesting that the xinyi xindian fault f2 and qiaobeizhen suqian fault f5 of the sstlfz are segmented which appear as thrust faults in the north and normal faults in the south the f2 f5 and mohe lingcheng fault f3 are inferred as quaternary faults based on the inversion of gravity anomaly the tectonic structure of the bedrock consists of two grabens and one horst and the moho discontinuity depth in the sihong area shows an obvious uplift we conclude that a fault depression superimposed basin developed inner the sstlfz the northern segments of the f2 and f5 were inverted due to the continuous compression since quaternary

scaling nature of crustal susceptibilities scale invariant or self similar properties have been demonstrated for a wide range of geophysical processes and rock properties evidence from well logs and inferences from aeromagnetic field power spectra suggest that crustal susceptibility also shows this behaviour with a power spectrum proportional to the 4 power of the spatial frequency we examine two large susceptibility measurement data sets and find that they both support the scaling hypothesis

intermediate sulfidation epithermal gold base metal deposits in tertiary subaerial volcanic rocks sahinli tespih dere lapseki western turkey abstract gold in the sahinli and tespih dere intermediate sulfidation gold base metal deposits in western turkey occurs in relatively deep epithermal quartz veins along with base metal minerals which have epithermal textures including plumose quartz vug infills comb and cockade textures and matrix supported milled breccias the total sulfide content of the veins in the area is variable ranging from fluid inclusions in main stage quartz at sahinli are only liquid rich with homogenization temperatures ranging from 220 to 322 c and the majority of th values between 250 and 300 c salinity ranges from 4 3 to 6 9 wt nacl equiv first ice melting temperatures tmf between 24 5 and 19 0 c indicate that the fluids were dominated by nacl h2o during mineralization the relatively higher average th at the tespih dere deposit 295 c is attributed to a relatively deeper level of exposure calculated 18o values indicate that ore forming hydrothermal fluids in the study area had 18oh2o ranging from 1 1 to 9 7 average 3 8 strongly 18o enriched compared with present day hydrothermal meteoric water in the area 18o 8 5 d values of fluid inclusions in quartz range from 58 to 93 and d values of clay minerals and alunite from 40 to 119 d values from intermediate argillic alteration average 68 in the study area are very similar to d values of the present day local geothermal system average d 54 whereas d values from advanced argillic alteration average d 33 are very different from the present day local geothermal system the 34s values in samples from the sahinli and tespih dere deposits average 2 9 for pyrite 3 3 for chalcopyrite 5 4 for sphalerite and 7 6 for galena these data are consistent with derivation of the sulfur from either igneous rocks or possibly from local wallrock

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

subsurface structural imaging of ceboruco volcano area nayarit mexico using high resolution aeromagnetic data abstract ceboruco volcano is one of the largest volcanoes of the trans mexican volcanic belt tmvb which extends along central mexico among the western tmvb ceboruco volcano comes in the second place after colima volcano in its activity also it is considered as the only one that has historically documented eruptions few geophysical studies have been published with the aim of studying the internal structure of the volcano in the current work and throughout the support of the cemiegeo p24 geothermal exploration project we aim to delineate the possible subsurface structural trends to determine the approximate depth to the basement surface and to provide an illustrative 3d model for its subsurface structure to achieve such goals a detailed analysis of the aeromagnetic data for the volcano area was performed 2d interpretation was carried out for the aeromagnetic data edge detection filters such as tilt derivative and analytic signal were used to map the contact faults within the study area in addition 3d inversion was used to image the subsurface structure of the volcano aeromagnetic data was inverted using the gmsys 3d inversion program by applying parker algorithm four subsurface layers at depths of 250 500 750 and 1000 m were assumed during the inversion process results indicate that the limits boundary of the subsurface magma chamber of the volcano can be traced easily from the first subsurface layer a secondary structure line appears towards the east from the volcano boundary and it can be observed from the inversion of the second and third layers this indicates that both the base of the volcano and the structure line stem from the same source finally they disappear in the inversion results for the last layer which concludes that we reach the basement above which the volcano is formed combination of all obtained results with the geological information helped to understand the main structure of the ceboruco volcano

lithospheric structure of the malawi rift implications for magma poor rifting processes this project was supported by the national science foundation continental dynamics nsf cd grant ear 1255233 and office of international and integrative activities oiia grant iia 1358150 this project is also supported by the nsf earthcube integration grant 1740627 we thank the computational infrastructure for geodynamics geodynamics org which is funded by the national science foundation under award ear 0949446 and ear 1550901 for supporting the development of advanced solver for problems in earth s convection

depth estimation from the scaling power spectrum of potential fields summary depth estimation from potential field power spectra requires a realistic assumption of the statistical properties of the source distributions density and susceptibility distributions in the earth s crust exhibit a long range dependence which is adequately described by scaling random fields with a spectral density proportional to some power of the wavenumber the theoretical power spectrum for a half space model of scaling sources explains the shape of observed power spectra of real potential field data very well minimizing the misfit between the model and the observed power spectrum yields an estimate for the depth to the top of the sources after demonstrating this approach on synthetic magnetic data we reinterpret power spectra of gravity and aeromagnetic data from utah hawaii and saskatchewan finding depth values that differ significantly from earlier interpretations all three power spectra are best explained by source distributions starting at surface level even the power spectrum from an aeromagnetic survey of a sedimentary basin with virtually non magnetic basin fill in the latter case a priori information on the intensity and the scaling exponent of the field caused by the basement had to be included to obtain an approximate estimate of the basin depth in general potential field power spectra are dominated by scaling properties of their source distributions and contain only limited depth information

direct observation and measurement of au and ag in epithermal mineralizing fluids abstract colloidal gold particles have been observed in c 300 c low salinity fluids from the arapucandere intermediate sulphidation epithermal base metal au deposit in nw turkey this is the first time colloidal gold has been recorded in an ancient mineralizing fluid growth in veins of large euhedral quartz crystals after the deposition of sulphides occurred in a number of stages from the introduction of fresh pulses of fluid the quartz overgrowths have a fibrous texture which facilitated trapping of large elongate fluid inclusions between the quartz fibres which grew perpendicular to the crystal faces of the pre existing quartz episodic periods of intense trapping of fluid inclusions occurred throughout the growth of quartz trapped within primary fluid inclusions are numerous particles of gold the largest observed is c 1 m but most are smaller bse element mapping shows these to contain au ag cu hg la icp ms profiles of the fluid inclusions confirm au and ag is not present in solution being present as numerous particles we have quantified the concentration of gold in fluid inclusions which are orders of magnitude greater than has been previously measured or thought likely in crustal fluids the average ag concentration is c 32 ppm and au is c 41 ppm but the maximum concentrations of both may reach several 100 s to 1000 ppm calcite forms a coating on the inner surface of the inclusions and barite pyrite galena sphalerite and unidentified minerals are also present with the au ag particles it is clear that the au ag particles could not have precipitated in the fluid inclusions therefore they must have precipitated elsewhere and been carried with the hydrothermal fluid the high concentrations and their colloidal nature have implications for the enrichment of gold in mineral deposits

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

downward continuation of magsat lithospheric anomalies to the earth s surface summary the assumed lithospheric component of magsat data is downward continued to the earth s surface over continental sized areas using the depleted basis method with a regularizing constraint parker shure 1982 to make the problem numerically tractable and stable respectively the depleted basis is arranged to have a high density of points over the area of interest lower elsewhere all three components at satellite altitudes are used in the inversion for three orthogonal components at the earth s surface edge effects are seen if the depleted basis changes rapidly from a high to low spatial density which are eliminated by inserting a region of intermediate density basis points the downward continued field fits the data to within their probable uncertainties regularizing the solution produces a much smoother solution for very little increase in misfit some of the anomalies in the downward continued field over africa correlate with known tectonic features although the relationship between magnetic highs or lows and basins or cratons is not clear cut this magsat derived downward continued field can be used to control the longer wavelength component of the crustal magnetic field that is not defined by aeromagnetic surveys the method is illustrated on an aeromagnetic compilation of about 30 surveys from south africa however there is a mismatch in amplitudes between the aeromagnetic data and downward continued magsat data

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

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

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

p t x constraints on the koru epithermal base metal au deposit biga peninsula nw turkey abstract the koru deposit is a typical intermediate sulfidation base metal au example of volcanic volcaniclastic hosted mineralization in the biga peninsula and northwestern turkey ore deposition was associated with the collisional and post collisional tectonics related to the closure of the tethys ocean galena baryte and quartz are main minerals accompanied by minor amounts of sphalerite pyrite chalcopyrite covellite and marcasite the homogenization temperature of fluid inclusions indicates two distinct fluid pulses one at a temperature commensurate with epithermal mineralization and boiling near boiling conditions at c 350 c with the second approximately 150 200 c lower salinity in both instances was from 11 0 to 0 2 wt nacl the d and 18o values of water in equilibrium with early quartz and fluid inclusions plot close to the magmatic water box indicating the source of the high temperature fluid was magmatic d and 18o values from early and late baryte trend towards the meteoric water line mwl but this is not due to mixing with meteoric water rather equilibration with alteration assemblages at decreasing temperature la icp ms analyses of fluid inclusions reveal high cu zn pb concentrations in the fluids despite their low salinity transported as chloride complexes the range of temperatures within the early quartz and sphalerite mineralization can be explained by pressure variations during vein and fracture opening

physico chemical controls on ore deposition in the arapucandere pb zn cu precious metal deposit biga peninsula nw turkey abstract arapucandere is one of a number of similar cu zn pb au ag epithermal deposits in the biga peninsula which are mineralogically and tectonically similar fluid inclusions have very low salinities between 1 7 and 0 wt nacl and a wide range of temperatures from 360 to 160 c there was extensive boiling and flashing of the hydrothermal fluids which initiated mineral deposition the range of temperatures is consistent with emplacement of the veins at 700 m depth with the pressure decreasing from near lithostatic to near hydrostatic and a decrease in temperature to 250 c due to adiabatic expansion of the fluids there is evidence of a limited amount of boiling but the temperature and pressure decrease was close to the liquid vapour curve flashing of the fluids was caused by sudden drops to sub hydrostatic pressures and even lower temperatures mineralization was caused by these pressure related temperature decreases as there is no evidence of cooling and dilution of the ore fluids 34 s values of sulphides indicate a magmatic source but the more negative than usual values also suggest boiling affected isotopes d and 18 o of the fluids indicate a mixing between meteoric waters and magmatic fluids with the large range of d due to boiling la icp ms analyses of fluid inclusions reveal high cu zn pb concentrations in the fluids despite their low salinity transported as chloride complexes exceptional pressure and temperature decrease causing the fluids to flash was likely to have been in response to earthquakes

identifying gravity anomalies caused by granitic intrusions in nanling mineral district china a multifractal perspective several power law relationships of geophysical potential fields have been discussed recently with renewed interests including field value distance f r and power spectrum wavenumber p models the singularity mapping technique based on the density concentration area c a power law model is applied to act as a highpass filter for extracting gravity and magnetic anomalies regardless of the background value and to detect the edges of gravity or magnetic sources with the advantage of scale invariance this is demonstrated on a synthetic example and a case study from the nanling mineral district southern china compared with the analytic signal amplitude and total horizontal gradient methods the singularity mapping technique provides more distinct and less noisy boundaries of granites than traditional methods additionally it is efficient for enhancing and outlining weak anomalies caused by concealed granitic intrusions indicating that the singularity method based on multifractal analysis is a potential tool to process gravity and magnetic data

the evolution from miocene potassic to quaternary sodic magmatism in western turkey implications for enrichment processes in the lithospheric mantle abstract new k ar dating and major and trace element analyses from the usak selendi emet use area constrain the timing of changes in the nature of volcanism in the miocene in western turkey the data reveal a change from dominantly calc alkaline and silicic in the early miocene to largely alkaline and more mafic volcanism in the middle miocene this probably reflects a decreasing amount of crustal contamination with time a result of extensional tectonics high levels of various incompatible elements including k in the more mafic members suggest an enriched subcontinental lithospheric source region for the middle miocene use lavas highly variable nb y ti y and th nb ratios suggest a lithospheric mantle heterogeneously enriched by two processes 1 enrichment by subduction related processes producing high th nb but low nb y and ti y and 2 enrichment by small degree melts of depleted upper mantle producing low th nb but high nb y and ti y both of these enrichment processes have variably contributed to middle miocene k rich lavas in the use area the mechanism which initiated the melting of the enriched lithosphere is considered to be extension which produced decompression melting comparisons with the nearby kula lavas reveals that by the pliocene to quaternary volcanism although still enriched in incompatible elements had become sodic it seems likely that continued extension up to this time thinned the lithosphere to such an extent that asthenospheric melts were produced which ascended and mixed with previously enriched lithosphere

genetic investigation and comparison of kartaldag and madendag epithermal gold deposits in canakkale nw turkey two epithermal gold deposits kartaldag and madendag located in nw turkey have been characterized through the detailed examinations involving geologic mineralogical fluid inclusion stable isotope whole rock geochemistry and geochronology data the kartaldag deposit 0 01 17 65 ppm au hosted by eocene dacite porphyry is associated with four main alteration types with characteristic assemblage of i chlorite smectite illite kaolinite ii quartz kaolinite iii quartz alunite pyrophyllite iv quartz pyrite the last being characterized by three distinct quartz generations comprising massive vuggy early fine medium grained vug lining early and banded colloform comb late textures observed sulfide minerals are pyrite covellite and sphalerite oxygen and sulfur isotope analyses performed on quartz delta o 18 quartz 7 93 to 8 95 parts per thousand and calculated delta o 18 h2o 7 95 to 1 4 parts per thousand and pyrite delta s 34 pyrite 4 8 parts per thousand and calculated delta s 34 h2s 6 08 to 7 20 parts per thousand separates suggest a meteoric water source for water in the hydrothermal fluid and an igneous source for the sulfur dissolved in ore related fluids microthermometric analyses of primary fluid inclusion assemblages performed on quartz late quartz generation yield temperatures th dominantly in the range of 245 285 degrees c and generally low salinity values at 0 to 1 7 wt nacl eq based on the quartz textures and the associated base metal concentrations along with fluid inclusion petrography the early vug lining quartz is considered to have been associated with the mineralization possibly through a boiling and a late mixing process at 285 degrees c the madendag deposit 027 20 60 ppm au hosted by paleozoic mica schists is associated with two main alteration types sericite illite kaolinite and quartz pyrite dominated by two distinct quartz generations i early colloform comb and banded quartz and ii late quartz forming the cement in hydrothermal breccia whereas oxygen isotope analyses of quartz delta o 18 quartz 9 55 to 18 19 parts per thousand and calculated delta o 18 h2o 2 97 to 5 54 parts per thousand suggest varying proportions of meteoric and magmatic sources for the ore bearing fluid sulfur isotope ratios delta s 34 pyrite 2 2 parts per thousand and calculated delta s 34 h2s 3 63 to 3 75 parts per thousand point to an essentially magmatic source for sulfur with or without contribution from sedimentary sources microthermometric analysis carried out on primary fluid inclusion populations of a brecciated sample early quartz give a temperature th range of 235 255 degrees c and 0 0 to 0 7 wt nacl eq salinity based on the textural relationship base metal and high gold contents the ore precipitation stage is associated with late stage quartz formation via a possible boiling process the presence of alunite pyrophyllite and kaolinite vuggy quartz and covellite suggest a high sulfidation type of epithermal deposit for kartaldag on the other hand madendag is identified as an adularia sericite type owing to the presence of significant sericite neutral ph clays mostly illite chlorite smectite and kaolinite low temperature quartz textures e g colloform comb and banded quartz and limited sulfide minerals given the geographical proximity of kartaldag and madendag deposits the similar temperature and salinity ranges obtained from their fluid inclusions and the similar ages of igneous rocks in both deposits kartaldag 40 80 036 to 42 19 0 45 ma madendag 43 34 0 85 ma the mineralizing systems in both deposits are considered to be genetically related c 2013 elsevier b v all rights reserved

comment on origin and evolution of hydrothermal fluids in epithermal pb zn cu au ag deposits at koru and tesbihdere mining districts canakkale biga peninsula nw turkey by mustafa cicek and tolga oyman ore geology review 2016 78 176 195

aeromagnetic study of the island of hawaii an aeromagnetic study of the island of hawaii provides new insight on magnetic properties of subsurface rock and geologic structure on a regional scale spectral depth analysis delineates two shallow magnetic zones each roughly 1 5 km thick lying at a depth of 1 km one zone of unknown origin lies in the center of the island and correlates with a regional magnetic high the other zone coincides with pronounced magnetic lows paralleling kilauea s active east rift zone these magnetic lows probably depict rocks chemically altered by hydrothermal fluids in which titanomagnetite has been destroyed analysis of magnetic terrain effects indicates that magnetization also decreases with depth within mauna kea and mauna loa we estimate that magnetization is reduced by about half at a depth of 1 km the magnetic method is particularly useful in delineating the lateral extent of local shield structures such as rifts summit calderas pit craters and vent fissures rifts possess characteristic magnetic patterns primarily long wavelength linear magnetic low zones we propose alteration processes reduce magnetizations along the flanks of rifts on the other hand along young rifts e g kilauea s east rift zone short wavelength magnetic anomalies probably reflect slowly cooled unaltered intrusions altered rock may also produce magnetic lows that help define buried summit calderas

detection of magnetically susceptible dyke swarms in a fresh coastal aquifer groundwater constitutes the main source of freshwater in shalatein on the western coast of the red sea in egypt the fresh aquifer of shalatein is intensively dissected by shallow and deep faults associated with the occurrence of dykes and or dyke swarms in this context synthesis of electrical resistivity ground magnetics and borehole data was implemented to investigate the freshwater aquifer condition locate the intrusive dykes and or dyke swarms and demarcate the potential freshwater zones nine schlumberger ves s with maximum current electrode half spacing ab 2 of 682 m were conducted the subsurface was successfully delineated by general four layers the fresh aquifer of the quaternary and pre quaternary alluvium sediments was effectively demarcated with true resistivities ranged from 30 to 105 m and thickness ranged between 20 and 60 m a ground magnetic survey comprised 35 magnetic profiles each 7 km in length magnetic data interpretation of the vertical derivatives first and second order downward continuation 100 m apparent susceptibility depth of 100 m and wavelength filters butterworth high pass of wavelengths 300 m clearly reflected the deep seated structure the computed depth by the 3d euler deconvolution for geological contacts and faults si 0 ranged from 14 to 545 m whereas for dyke and sill si 1 it ranged from 10 to 1 095 m the western part of the study area is recommended as a potential freshwater zone as it is characterized by depths 100 m to the top of the dykes higher thickness of the fresh aquifer 45 60 m depths to the top of the fresh aquifer ranging from 25 to 40 m and higher resistivities reflecting better freshwater quality 70 105 m

quartz types authigenic and detrital in the upper cretaceous eagle ford formation south texas usa abstract lithologic heterogeneity of the eagle ford formation in south texas arises from mixing of extrabasinal grains of siliciclastic composition with intrabasinal grain assemblages composed dominantly of marine carbonate with a lesser component of biosiliceous debris detrital quartz in particular is derived from both extrabasinal and intrabasinal sources posing a challenge for the use of bulk compositional data for mudrock classification extrabasinal detrital quartz supplied along a major axis of siliciclastic influx the woodbine depositional system of east texas is reduced to a minor part of the grain assemblage in south texas petrographic evidence and point count results indicate that around 85 percent of total quartz in these rocks equal to about 12 6 volume percent is authigenic thus significant quantities of authigenic silica are not restricted to siliceous mudrocks but can be found in carbonate rich mudrocks as well formerly opaline skeletons of radiolaria the dominant source of silica for authigenic quartz precipitation are only poorly preserved by replacements including calcite dolomite pyrite and quartz dissolved silica released by dissolution of radiolarians and perhaps also by volcanic glass dissolution is re precipitated in a variety of forms including matrix dispersed microquartz cement fillings within primary intragranular pores and grain replacement of both calcareous and siliceous allochems the mass balance of dissolved silica mobilized from radiolarians and other reactive silicates and the precipitation of authigenic quartz is uncertain because the initial volumes of now dissolved detrital material versus the final volume of authigenic material quartz and other authigenic silicates cannot be determined with accuracy

ovacik gold deposit an example of quartz adularia type gold mineralization in turkey the ovac1k gold deposit is located 100 km north of izmir in western turkey it lies adjacent to the east northeast trending bergama graben and it consists of a series of high grade gold bearing epithermal quartz veins hosted by subaerial andesitic dacitic lava dome facies of lower miocene age the region is underlain by paleozoic metamorphic rocks and limestone which are cut by medium to high level intrusions and overlain by subaqueous and subaerial andesitic to dacitic lava domes that host the ovac1k gold deposit middle to late miocene extensional tectonic activity was responsible for the formation of north northeast south southwest to northeast southwest trending grabens the extensional activity was accompanied by normal faulting with a later variable sinistral strike slip component oriented east west and northwest southeast it is probable that these faults were critical in controlling the development of epithermal quartz veins both mineralized and unmineralized two of four nearly east west trending epithermal veins at ovac1k contain significant au mineralized areas and display typical low temperature epithermal textures including crustiform banding quartz pseudomorphs after bladed calcite and multiphase hydrothermal breccias veins crop out throughout a maximum strike length of 400 m and surface widths are up to 35 m mineralized areas extend down dip for at least 200 m gold appears to be related mainly to earlier formed quartz adularia veins and breccias the gold occurs mainly in clasts of earlier vein material that has been transported from deeper levels in the vein system little gold is contained in the matrix of the breccias the alteration associated with mineralization consists of secondary albite or adularia together with quartz and clays such as smectite interlayered illite smectite and illite chlorite illite and chlorite metallic minerals occur generally only in trace amounts and include chalcopyrite pyrite arsenopyrite sphalerite bornite chalcocite covellite galena and electrum the mineralizing fluids had temperatures ranging from 150 to 250 c and salinities between 7 0 and 8 0 wt percent nacl equiv the veins have a distinct trace element signature including high au ag as and sb high au and ag with low as and sb contents are found in the quartz adularia veins whereas low au and ag with high as and sb are found in the silicified hanging wall and footwall zones drilling has confirmed continuity of mineralized rock to a vertical depth of 175 m to date a resource of 2 980 000 tonnes at 9 0 g t au containing 862 000 ounces has been delineated other deposits of this type should be sought where late oligocene to early miocene volcano plutonic rocks are cut by major northeast southeast trending grabens with associated northwest southeast to east west oriented normal to sinistral strike slip faults volcanic rocks with strong adularia sericite alteration and silicification accompanied by quartz veins with epithermal textures are primary targets

analysis of magnetic data over part of the younger granite province of nigeria the results of a magnetic study of part of the younger granite province of nigeria are presented here spectral analysis of the magnetic anomalies over the area has been carried out in an effort to estimate the depth to magnetic sources average magnetic source depth of 286 m has been obtained for the area and this is thought to be related to the depth to the top of the main anomalous structures in the area observed magnetic anomaly profiels taken across the area have been interpreted in terms of arbitrarily shaped bodies whose existence was confirmed by 3 d hilbert transformation using nonlinear optimization techniques the modelled bodies occur at depths of 200 760 m and have magnetizations of 0 29 0 47 a m the results from the analysis of the magnetic field are discussed in relation to the results from previous gravity studies over the area and the mode of emplacement of the younger granites