first evidence of high pressure metamorphism in the cover series of the southern menderes massif tectonic and metamorphic implications for the evolution of sw turkey abstract the menderes massif occupies a large part of western turkey it is tectonically overlain by nappes of the izmir ankara suture zone including the bornova flysch zone on its northern flank the afyon zone on its eastern border and the lycian nappes on its southern flank the discovery of magnesiocarpholite kyanite assemblages in the mesozoic cover sequence of the southern menderes massif leads to the very first consideration that a major high pressure hp metamorphic event affected the massif during its alpine evolution estimations of minimum pressure temperature conditions about 10 12 kbar and 440 c suggest a minimum burial of 30 km for the metasedimentary rocks of the menderes massif similar to that for the eocene dilek blueschists which belong to the cycladic complex this finding of high pressure rocks within the menderes cover series as well as the recent description of low grade high pressure parageneses in the basal thrust sheets of the overlying lycian nappe complex has strong implications for the tectono metamorphic evolution of these units the characteristics of this high pressure metamorphism and the deformation features observed in the southern menderes massif allow consideration of a fast burial during alpine subduction and nappe stacking three high pressure units were piled up during the eocene collision of the sakarya continent and the tauride menderes block the lowermost unit consists of the imbricated core and cover of the menderes massif the intermediate unit is the cycladic blueschist complex dilek and samos regions and the uppermost unit is made of the lycian nappes the retrogression of high pressure parageneses from the menderes massif follows an isothermal decompression path and the associated deformation is characterized by a severe stretching oriented n s to ne sw during the high pressure event and its exhumation we propose a tectono metamorphic model in three main stages 1 the southward translation of the high pressure lycian nappes and the burial of the menderes and cycladic metasediments to a depth of at least 30 km to allow their eocene high pressure metamorphism 2 a northward continuum of deformation responsible for top to the north fabrics associated with the main menderes metamorphism peak paleocene eocene and its progressive cooling late eocene north verging folding thrusting imbrication of core and cover series and n s to ne sw intense stretching associated with the menderes high pressure metamorphism and its exhumation these top to the north to top to the northeast movements are probably related to the northward backthrusting of the lycian nappes reactivating the contact between the menderes massif and the lycian nappes as a top to the ne shear zone that allowed exhumation of the lycian high pressure rocks 3 oligo miocene n s extension during which the final exhumation of the metamorphic rocks along kilometre scale low angle detachments occurred

timing kinematics and cause of aegean extension a scenario based on a comparison with simple analogue experiments abstract since the early 1970s most geodynamic models proposed for the eastern mediterranean consider that the initiation of extension in the aegean during the late middle miocene or later was a direct consequence of the westward extrusion of anatolia away from the arabia eurasia collision front in the late 1990s a few models have taken into account the increasing evidence for an earlier initiation of aegean extension arising mostly from the analysis of deformation within the various alpine metamorphic complexes of the area based largely on our own investigations we first present a review of the data that reliably constrain the minimum age for the initiation of extension in these complexes it shows that regional scale extension with a pattern of stretching orientations similar to that of the pliocene pleistocene was already strongly active in the aegean before the onset of arabian indentation into eurasia lower miocene vs middle or upper miocene this implies that the initiation of aegean extension did not result from the lateral extrusion of anatolia instead extension may have started owing to a process of gravity spreading of the continental lithosphere that had previously been thickened during alpine collision the main arguments favouring this interpretation are presented and a preliminary scenario is proposed for the neogene evolution of the eastern mediterranean in which lateral extrusion of anatolia occurred lately during southward spreading of the aegean lithosphere in order to test this hypothesis further physical experiments simulating the horizontal spreading of a continental lithosphere toward a free boundary have been carried out the analysis of various elements of the deformation field displacements strain rotations fault pattern and kinematics both in the experiments and in the aegean domain reveals an excellent agreement between the two not only do early stages of aegean extension appear to fit the gravity spreading hypothesis but so does the recent to present internal deformation of the aegean transverse e w active shortening observed in the northern aegean is commonly taken as one of the most striking pieces of evidence that aegean extension results from the lateral extrusion of anatolia the experiments indicate that such transverse shortening may equally develop as a result of pure gravity spreading associated with a pattern of faults and rotations that compares well with that of the northern aegean pure dextral shearing along some strands of the north aegean trough fault system and the related development of an asymmetric pattern of faults in the northern aegean are eventually the only features that evidently arise from the extrusion of anatolia since less than 3 ma finally we argue that during the early stages of aegean extension since at least 21 ma and until ca 11 ma the distribution of extensional strain on a regional scale has been controlled by the distribution of earlier thickening post thickening thermal weakening through partial melting of deep levels of the crust probably accounts for the localization of extensional strain within the areas of thick crust restoring the aegean in its most likely configuration at the onset of bulk crustal extension suggests that 1 the extensional strain rate remained roughly constant or has eventually decreased since the onset of aegean extension and 2 the amounts of extension before and after 16 ma have been roughly equal

proto tethyan remnants in northwest iran geochemistry of the gneisses and metapelitic rocks abstract the iran continental crust was metamorphosed intruded by granitoid magmas folded and faulted during the late precambrian by the pan african orogeny the basement complex in the takab complex northwest iran consists of gneisses amphibolites pelitic schists meta ultramafic and calc silicate rocks geochemically the protoliths of the takab gneisses are slightly peraluminous and medium to high potassic with calc alkaline affinity these gneisses may have been emplaced in volcanic arc tectonic setting furthermore the metapelitic protolith is shale deposited in an active continental margin setting all these characteristics and presence of paleo suture zone and ophiolitic rocks i e serpentines meta mafic and meta ultramafic rocks around the high grade metamorphic rocks suggest that a continental margin magmatic arc andean type formed the takab precambrian basement the basement complexes are extensively overprinted by the pan african orogeny and younger igneous events this supports the inference that early cambrian orogenesis in the takab complex region of northwest iran marks one of the fundamental lithospheric boundaries within gondwana which belonged to a greater late neoproterozoic early paleozoic orogenic system that was active along the proto tethyan margin of the gondwana supercontinent extending at least from its arabian margin to the himalayan margin of the indian subcontinent

hydrochemical characteristics and salinity of groundwater in the ejina basin northwestern china a hydrochemical investigation was conducted in the ejina basin to identify the hydrochemical characteristics and the salinity of groundwater the results indicate that groundwater in the area is brackish and are significantly zonation in salinity and water types from the recharge area to the discharge area the ionic ration plot and saturation index si calculation suggest that the silicate rock weathering and evaporation deposition are the dominant processes that determine the major ionic composition in the study area most of the stable isotope 18o and d compositions in the groundwater is a meteoric water feature indicating that the groundwater mainly sources from meteoric water and most groundwater undergoes a long history of evaporation based on radioactive isotope tritium 3h analysis the groundwater ages were approximately estimated in different aquifers the groundwater age ranges from less than 5 years between 5 years and 50 years and more than 50 years within 1 km of the river water influence zone the groundwater recharges from recent heihe river water and the groundwater age is about less than 5 years in shallow aquifer from 1 km to 10 km of the river water influence zone the groundwater sources from the mixture waters and the groundwater age is between 5 years and 50 years in shallow aquifer the groundwater age is more than 50 years in deep confined aquifer

eclogites within the menderes massif western turkey metagabbros in the core series of the menderes massif for some time considered as post orogenic miocene intrusives revealed a strong poly metamorphic history the metagabbro bodies exhibit a pronounced zonation within their cores igneous minerals are still preserved coronitic textures are interpreted as results of a high temperature possibly granulitic overprint the outer parts of the metagabbro bodies mostly consist of strongly to completely retrograded garnet amphibolites but occasionally contain relics of eclogites petrologic investigations confirmed a high pressure overprint and allowed preliminary p t estimates 650 c 1 3 gpa the intensity of the hp metamorphism seems to rise from south to north within the menderes basement thus pointing to a northward subduction as the cause the age of the high pressure event still awaits clarification however its very existence reanimates the question how close the relationship between menderes and the cyclades evolution might have been

cambrian ordovician depositional sequences in the middle east a perspective from turkey abstract in southern turkey taurus chain or taurides and southeastern turkey border folds of the arabian plate nearly complete cambrian to ordovician successions are preserved four major sedimentary sequences are defined according to the main transgressive events and the subsequent shelf progradations these sequences allow us to link the turkish mostly distal lower palaeozoic detritals to the more proximal arabian formations in spite of contrasting facies the lower palaeozoic development is outlined through four successive steps defined in southern turkey 1 initiation of a cratonic platform regime terreneuvian i e earliest cambrian depositional sequence 1 with fluviatile conglomerates and red bed sediments associated with volcanics 2 development of a stable marine platform late terreneuvian to early ordovician depositional sequences 2 and 3 including widespread but diachronous middle cambrian carbonates and subsequent storm dominated detritals 3 tectonic instability middle ordovician leading to a new palaeogeography on the gondwana platform with the differentiation of a sag basin bedinan qasim depocenter lower part of depositional sequence 4 and 4 glaciation latest ordovician upper part of depositional sequence 4 identified by glaciomarine deposits forming the hirnantian glacial record this thick 2000 m detrital succession records a first order long term subsidence driven cambrian to ordovician transgressive trend and includes second order sequences reflecting interactions between global eustasy and tectonic instability on a larger scale the identification of recurrent sequence stratigraphic features with similar trends in the cambrian ordovician successions on the arabian platform implies that a former location of the taurus domain cannot be situated in the present day eastern mediterranean area but should lie directly north of the arabian platform this location places southern turkey at the junction between the north african segment of the gondwana siliciclastic shelf to the west present day coordinates and the eastern arabian segment in good agreement with mixed faunal signatures from both areas primary control of the tectonostratigraphic development of southern turkey during the lower palaeozoic may be a forced evolution from arc platform to rift drift transitions cordilleran model that has migrated progressively eastwards from the avalonian domain along the northern gondwana margin to the arabian domain throughout the lower palaeozoic

terrestrial freshwater lenses unexplored subterranean oases freshwater lenses are lenticular bodies of fresh tds 1000 mg l groundwater that develop above more saline groundwater within the same host aquifer due in part to buoyancy in contrast to the widely studied situation of freshwater lenses in coastal aquifers the formation location and persistence of freshwater lenses in terrestrial settings are poorly understood this is despite inland aquifers commonly containing saline groundwater particularly in arid and semi arid climates and the local occurrences of freshwater being critical for ecosystems and human endeavour we identify and classify known terrestrial freshwater lenses tfls using four formation categories namely topography geology groundwater surface water interaction and recharge mechanisms the resulting typology highlights the importance of buoyancy in the formation of tfls in otherwise unlikely situations implying that tfls may be more prevalent than previously thought tfls represent some of the most vulnerable and precious freshwater resources on earth that require considerably more research into mechanisms of formation and threats to their existence

miocene nne directed extensional unroofing in the menderes massif southwestern turkey structural investigations in the central part of the menderes massif odemio kiraz submas sif reveal the presence of a large scale low angle extensional shear zone with a top to the n ne shear sense regional ductile deformation was accompanied by the intrusion of two syntectonic granodiorites that have been dated with the 40 ar 39 ar method one hornblende isochron age of 19 5 1 4 ma and two biotite plateau ages of 13 1 0 2 and 12 2 0 4 ma respectively constrain that extension was already active in the early miocene successive tectonic denudation of the odemio kiraz submassif resulted in the formation of a n dipping detachment fault in which ductile fabrics were severely reworked by cataclasis under decreasing temperature syntectonic neogene sediments currently exposed along the southern margin of the gediz graben were deposited in the hanging wall of the extensional fault system and were tectonically emplaced onto the cataclasites during progressive exhumation minor rotation c 15 caused southward tilting of the sediments ongoing nne directed extension created a steep normal fault that truncates the detachment fault and constitutes the southern boundary fault of the gediz graben

garnet and associated minerals in the southern margin of the menderes massif southwest turkey assemblages with muscovite quartz show a regular increase in grade from the chlorite zone at the base of the lycian nappe complex to the garnet zone within the structurally underlying menderes massif biotite enters before garnet which precedes oligoclase garnet bearing assemblages in pelites are compared with those in re equilibrated quartzofeldspathic gneisses where garnet is unusually calcic in one case approaching gross 50 alm 50 garnet zoning with mn decreasing outwards is interpreted as growth zoning ca decreases outwards in pelite garnets but shows the reverse effect in the gneisses chloritoid is common but rarely coexists with biotite and garnet chlorite paragonite is found rather than chloritoid albite garnet biotite geothermometry corrected for the effect of ca in garnets with up to 29 mole grossular indicates temperatures of 530 or 50 degrees c near the garnet isograd muscovite paragonite geothermometry gives an anomalous result metamorphic pressure is considered in the light of i mn fe partition between garnet and biotite ii ca content of garnet coexisting with plagioclase muscovite biotite iii na in actinolite coexisting with albite chlorite magnetite and iv celadonite content of muscovite which however shows variation due to disequilibrium within a specimen and does not provide an accurate geobarometer comparisons with published studies indicate a strong similarity to the barrovian dalradian of scotland and lead to a tentative pressure estimate of approximately 5 kbar modified journal abstract

how to resist subduction evidence for large scale out of sequence thrusting during eocene collision in western turkey significant along strike variations have locked large parts of the alpine subduction complex in the eastern mediterranean in the eocene and defined the end of high pressure accretion in western turkey structural analysis reveals that the anatolide belt in western turkey formed under greenschist facies metamorphic conditions in the eocene when a high pressure metamorphic fragment of the adriatic plate the cycladic blueschist unit was thrust onto the imbricated mid crustal units of the anatolian microcontinent the menderes nappes the contact between the cycladic blueschist unit and the menderes nappes the cyclades menderes thrust represents an out of sequence ramp which cuts up section towards the south the lack of alpine high pressure fabrics below the cyclades menderes thrust implies c 35 km of exhumation of the cycladic blueschist prior to its eocene emplacement on top of the menderes nappes structure and geodynamic evolution of the anatolide belt are in striking contrast to the neighbouring aegean and contradict the model of a laterally continuous orogenic zone in which the anatolide microcontinent is interpreted as an eastern extension of the adriatic plate

the use of environmental tracers to determine focused recharge from a saline disposal basin and irrigation channels in a semiarid environment in southeastern australia summary lake tutchewop in southeastern australia is a former ephemeral wetland that has been used as a saline disposal basin since 1968 forming part of the salinity management of the murray river the extent of saline focused recharge from lake tutchewop and fresh recharge from nearby unlined irrigation channels was determined using pore water and groundwater stable isotope and major ion chemistry which were able to separate the influence of lake water irrigation water and regional groundwater in 45 years saline water from lake tutchewop has infiltrated only up to 165 m from the lake edge in most directions due to the underlying relatively impermeable clay rich sediments and a maximum of 700 m due to preferential groundwater flow along a sandy palaeochannel the saline leakage has had limited if any impact on surrounding agricultural land use fresh water leakage from unlined irrigation channels extends up to 10 m deep validating the current program to replace these channels with pipelines this study demonstrates that focused recharge from different sources can be positively identified where the recharge waters have distinctive compositions and that underlying clay rich sediments restrict the extent of seepage therefore management of focused recharge sources particularly those that could decrease groundwater quality requires a detailed knowledge of both the groundwater composition around the site and the underlying geology

seismic structure crustal architecture and tectonic evolution of the anatolian african plate boundary and the cenozoic orogenic belts in the eastern mediterranean region the modern anatolian african plate boundary is represented by a north dipping subduction zone that has been part of a broad domain of regional convergence between eurasia and afro arabia since the latest mesozoic a series of collisions between gondwana derived ribbon continents and trench roll back systems in the tethyan realm produced nearly east west trending subparallel mountain belts with high elevation and thick orogenic crust in this region ophiolite emplacement terrane stacking high p and barrovian metamorphism and crustal thickening occurred during the accretion of these microcontinents into the upper plates of tethyan subduction roll back systems during the late cretaceous early eocene continued convergence and oceanic lithospheric subduction within the tethyan realm were punctuated by slab breakoff events following the microcontinental accretion episodes slab breakoff resulted in asthenospheric upwelling and partial melting which facilitated post collisional magmatism along and across the suture zones resumed subduction and slab roll back induced upper plate extension triggered a tectonic collapse of the thermally weakened orogenic crust in anatolia in the late oligocene miocene this extensional phase resulted in exhumation of high p rocks and mediumto lower crustal material leading to the formation of metamorphic core complexes in the hinterland of the young collision zones the geochemical character of the attendant magmatism has progressed from initial shoshonitic and high k calc alkaline to calc alkaline and alkaline affinities through time as more asthenosphere derived melts found their way to the surface with insignificant degrees of crustal contamination the occurrence of discrete high velocity bodies in the mantle beneath anatolia as deduced from lithospheric seismic velocity data supports our tethyan slab breakoff interpretations pn velocity and sn attenuation tomography models indicate that the uppermost mantle is anomalously hot and thin consistent with the existence of a shallow asthenosphere beneath the collapsing anatolian orogenic belts and widespread volcanism in this region the sharp north pointing cusp isparta angle between the hellenic and cyprus trenches along the modern anatolian african plate boundary corresponds to a subductiontransform edge propagator step fault which is an artifact of a slab tear within the downgoing african lithosphere

south menderes monocline low temperature thermochronology constrains role of crustal extension in structural evolution of southwest turkey abstract we report apatite and zircon fission track data across the contact zones between the menderes nappes the cycladic blueschist unit and the oren nappe in the anatolide belt of southwest turkey these data resolve previous debate on the deformation history of these cretaceous to eocene nappe contacts including whether they were reactivated during late oligocene to miocene crustal extension apatite fission track ages range from 18 to 28 ma in the menderes nappes and 31 to 42 ma in the oren nappe zircon fission track ages are 29 to 31 ma in the menderes nappes 30 to 33 ma in the cycladic blueschist unit and between 93 ma and 129 ma in the oren nappe the data reveal that the tectonic contacts within the menderes nappes and with the overlying cycladic blueschist unit have been sealed since 35 30 ma in the oren nappe zircon fission track ages are distinctly older with mixed single grain ages between 300 and 75 ma reflecting partial to full resetting during late cretaceous high pressure metamorphism the contact between the cycladic blueschist unit and the oren nappe shows no significant tectonic movement in the brittle crust after 70 ma these data reveal that the nappe boundaries in the southern menderes massif have undergone no significant differential offset relative to the earth s surface since the oligocene and therefore were not reactivated during late oligocene to miocene continental extension we interpret the steeply dipping portion of the nappe pile in the southern menderes massif as a tilted crustal section which we name the south menderes monocline we speculate this monocline formed by differential uplift in the miocene either at the hinge zone of a plateau or by unloading of the simav detachment footwall

geochemistry geochronology and cathodoluminescence imagery of the salihli and turgutlu granites central menderes massif western turkey implications for aegean tectonics abstract the menderes massif western turkey is an important metamorphic core complex located in the aegean region geochemical and geochronological data from this extensional domain facilitates our understanding of large scale extension of the earth s lithosphere s type peraluminous granites salihli and turgutlu that intrude the alasehir detachment which bounds the northern edge of the central menderes massif may have been generated due to subduction of the eastern mediterranean floor along the hellenic trench in situ th pb ion microprobe monazite ages from the granites range from 21 7 4 5 ma to 9 6 1 6 ma 1 higher uncertainty in the ages is attributed to monazite common pb but the range is consistent with cathodoluminescence cl imagery that document complex textures within the samples salihli and turgutlu granites share many similar characteristics including multiple generations of plagioclase some with shocked cores plagioclase replacing k feldspar and the development of myrmekite evidence for fluid interaction and multiple generations of microcracks and microfaults the granites may have evolved from compositionally distinct magma sources as salihli samples in general contain allanite as the major accessory mineral whereas turgutlu granites contain monazite however the cl imagery document similar alteration textures the youngest turgutlu monazite grain 11 5 0 8 ma is located in the rim of a k feldspar grain close to myrmekite and the youngest salihli monazite grain 9 6 1 6 ma is located in the outer edge of an altered plagioclase crystal these ages likely time episodes of deformation as the granites were subjected to exhumation along the alasehir detachment ages reported here are similar to dates constraining extension reported elsewhere in the aegean but indicate a level of complexity when linking movement within the menderes massif to the large scale geodynamic processes that created other metamorphic core complexes in the region difficulties exist in linking the ages obtained from the granites to specific tectonic events due to the presence of secondary alteration textures generations of mineral growth and multiple episodes of deformation

aegean tectonics strain localisation slab tearing and trench retreat abstract we review the geodynamic evolution of the aegean anatolia region and discuss strain localisation there over geological times from late eocene to present crustal deformation in the aegean backarc has localised progressively during slab retreat extension started with the formation of the rhodope metamorphic core complex eocene and migrated to the cyclades and the northern menderes massif oligocene and miocene accommodated by crustal scale detachments and a first series of core complexes mccs extension then localised in western turkey the corinth rift and the external hellenic arc after messinian times while the north anatolian fault penetrated the aegean sea through time the direction and style of extension have not changed significantly except in terms of localisation the contributions of progressive slab retreat and tearing basal drag extrusion tectonics and tectonic inheritance are discussed and we favour a model 1 where slab retreat is the main driving engine 2 successive slab tearing episodes are the main causes of this stepwise strain localisation and 3 the inherited heterogeneity of the crust is a major factor for localising detachments the continental crust has an inherited strong heterogeneity and crustal scale contacts such as major thrust planes act as weak zones or as zones of contrast of resistance and viscosity that can localise later deformation the dynamics of slabs at depth and the asthenospheric flow due to slab retreat also have influence strain localisation in the upper plate successive slab ruptures from the middle miocene to the late miocene have isolated a narrow strip of lithosphere still attached to the african lithosphere below crete the formation of the north anatolian fault is partly a consequence of this evolution the extrusion of anatolia and the aegean extension are partly driven from below asthenospheric flow and from above extrusion of a lid of rigid crust

geology of the bozdag area central menderes massif sw turkey pan african basement and alpine deformation the menderes massif consists of a precambrian core series that preserves evidence for a polymetamorphic history and a paleozoic mesozoic cover series that experienced only the alpine tectonometamorphic evolution structural petrographic and geochronologic investigations in the central menderes massif demonstrate that a part of the metamorphic and structural evolution of the precambrian basement is older than the undeformed 551 1 4 ma old birgi metagranite and b inferred alpine fabrics overprinting the cover series largely have the same attitudes as the old structures in the much older core series the inferred alpine fabrics include both contractional and extensional structures contraction under greenschist to amphibolite facies conditions resulted in the imbrication of the core and cover series and generated an inverted metamorphic sequence by north directed thrusting during alpine extension most of the south dipping thrust faults were reactivated as extensional shear zones under decreasing greenschist facies conditions

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

southern menderes massif an incipient metamorphic core complex in western anatolia turkey in the southern sector of the menderes massif north of selimiye milas augen gneisses interpreted as a deformed peraluminous granite have been dynamothermally metamorphosed and are surrounded by and intrude a regionally metamorphosed palaeozoic envelope the granitic rocks exhibit a moderately dipping mylonitic foliation and nne ssw trending mineral elongation lineation the progressive deformation of the granitic rocks produces a structural sequence typical of an extensional shear zone marked from bottom to top by a very thick extensive zone of mylonites followed in turn by brecciated mylonite and cataclasite the kinematic indicators exhibit a top to the south down dip sense of shear these structures are attributed to exhumation of the granitic rocks of the massif along a major south dipping normal sense shear zone that accommodated crustal extension during late oligocene collapse of the orogen in western turkey thus the southern menderes massif may be interpreted as the exhumed footwall of a major extensional shear zone and possibly as an incipient core complex

late cenozoic cooling history of the central menderes massif timing of the buyuk menderes detachment and the relative contribution of normal faulting and erosion to rock exhumation abstract based on new thermochronological data and 10be derived erosion rates from the southern part of the central menderes massif aydin block in western turkey we provide new insights into the tectonic evolution and landscape development of an area that undergoes active continental extension fission track and u th he data reveal that the footwall of the buyuk menderes detachment experienced two episodes of enhanced cooling and exhumation assuming an elevated geothermal gradient of 50 c km the first phase occurred with an average rate of 0 90 km myr in the middle miocene and the second one in the latest miocene and pliocene with a rate of 0 43 km myr the exhumation rates between these two phases were lower and range from 0 14 to 0 24 km myr depending on the distance to the detachment cosmogenic nuclide based erosion rates for catchments in the aydin block range from 0 1 to 0 4 km myr the similarity of the erosion rates on both sides of the aydin block northern and southern flank indicate that a rather symmetric erosion pattern has prevailed during the holocene if these millennial erosion rates are representative on a million year timescale they indicate that apart from normal faulting erosion in the hanging wall of the buyuk menderes detachment fault did also contribute to the exhumation of the metamorphic rocks

granitoid rocks of the southern menderes massif southwestern turkey field evidence for tertiary magmatism in an extensional shear zone recent field campaign in the southern menderes massif in southwestern turkey revealed that the so called core of the massif comprises two distinct types of granitoid rocks an orthogneiss traditionally known as augen gneisses and leucocratic metagranite where the latter is intrusive into the former and the structurally overlying cover schists these differ from one another in intensity of deformation degree of metamorphism and kinematics the orthogneiss display penetrative top to the n nne fabrics formed under upper amphibolite facies conditions during the eocene main menderes metamorphism mmm whereas foliation and stretching lineation exists in the leucocratic metagranites but are not strongly developed the leucocratic metagranites show evidence of syn to post emplacement deformation in a series of weakly developed top to the s ssw fabrics formed under lower greenschist facies conditions leucocratic metagranite bodies occur all along the augen gneiss schist contact in the southern menderes massif they are emplaced as sheet like bodies into country rocks previously deformed and metamorphosed during a top to the n nne alpine orogeny along a ductile extensional shear zone located between orthogneisses and metasediments which was possibly active during emplacement the data presently available indicate that emplacement and associated ductile extensional deformation occurred during late oligocene early miocene time these results confirm previous contentions that there are tertiary granites in this part of the menderes massif

extensional v contractional origin for the southern menderes shear zone sw turkey tectonic and metamorphic implications the southern menderes massif in southwest turkey consists mainly of orthogneisses and overlying palaeozoic middle paleocene schists and marbles the contact between the two distinct rock types is almost everywhere structural herein named the southern menderes shear zone a s facing high angle ductile shear zone that separates metamorphic rocks of differing grade although there is a consensus that the shear zone was associated with top to the s ssw shearing and is of tertiary age its origin and nature have been highly debated over the last decade some claim the contact is a thrust fault while others have argued for an extensional shear zone integration of field and microstructural data the identification of different fabrics associated kinematics and overprinting relationships with fission track thermochronology and the p t paths of the rocks above and below the shear zone supports the conclusion that the southern menderes shear zone is an extensional shear zone and not a thrust the data are consistent with a model that the exhumation and cooling of the southern menderes massif occurred after a period of extensional deformation pervasive top to the n nne high temperature medium pressure ductile shear structures d 2 deformation overprint an early hp event d 1 deformation the subsequent top to the s ssw greenschist shear band foliation d 3 deformation developed mostly around the orthogniess schist contact and forms the most characteristic features of the massif the top to the n nne structures are attributed to the main alpine constructional deformation that developed during back thrusting of the lycian nappes during the latest palaeogene collision between the sakarya continent and the anatolide tauride platform across the neotethyan ocean the top to the s ssw structures are interpreted to be the result of the exhumation of the massif during the activity of the southern menderes shear zone the presence of these two distinct fabrics with differing kinematics suggests that the southern menderes shear zone operated as a top to the n nne thrust fault during early alpine contractional deformation but was later reactivated with an opposite sense of movement top to the s ssw during subsequent oligocene miocene extensional collapse

the menderes massif of western turkey and the cycladic massif in the aegean do they really correlate based on lithostratigraphic comparisons the menderes massif has been correlated with the cycladic massif thereby implying that the eastern mediterranean consists of a narrow pre alpine basement belt which is laterally continuous over a long distance and which experienced a similar alpine orogenic history our work indicates that the architecture the age of basement and the pre alpine and alpine tectonometamorphic history of both massifs differ fundamentally from each other the menderes massif consists of remnants of the cycladic massif which overly an exotic unit the menderes nappes both massifs do not represent lateral continuations which has implications for palaeogeographic reconstructions

late cretaceous to paleocene oroclinal bending in the central pontides turkey 1 the turkish pontide fold and thrust belt formed since the paleozoic and is an important element in the africa eurasia convergence and the resulting closure of the neo tethys ocean it has a peculiar arc shaped geometry in its central part along the black sea coast which may have resulted from oroclinal bending we have determined the vertical axis rotation history of this area using paleomagnetism on cretaceous to eocene rocks from 47 sites and critically analyzed previously published data we applied the same reliability criteria to all data our results show that late cretaceous sites have clockwise and counterclockwise rotations perpendicular to the structural trend in the central pontides in the eastern pontides they show only local rotations paleocene to eocene rocks in the central and eastern pontides show no rotation we conclude that the central pontide northward arc shaped geometry results from oroclinal bending in latest cretaceous to earliest paleocene times the timing and scale of geological processes that occurred in the region make it likely that orocline formation resulted from neo tethys closure between the pontides and the metamorphic promontory of the anatolide tauride block earlier studies on the southerly located cankiri basin reveal that clockwise and counterclockwise rotations occurred in eocene oligocene times this implies that the entire region underwent continuous deformation from late cretaceous to eocene caused by convergence of the pontides and the anatolide tauride block with a southward moving deformation front deformation was first localized in the northern part of the central pontides until the paleocene resulting in oroclinal bending and from at least eocene times it shifted toward the cankiri basin region

geochemical and temporal evolution of cenozoic magmatism in western turkey mantle response to collision slab break off and lithospheric tearing in an orogenic belt post collisional magmatism in western anatolia began in the eocene and has occurred in discrete pulses throughout the cenozoic as it propagated from north to south producing volcano plutonic associations with varying chemical compositions this apparent sw migration of magma tism and accompanying extension through time was a result of the thermally induced collapse of the western anatolian orogenic belt which formed during the collision of the sakarya and tauride anatolide continental blocks in the late paleocene the thermal input and melt sources for this prolonged magmatism were provided first by slab break off generated aesthenospheric flow then by lithospheric delamination related aesthenospheric flow followed by tectonic extension driven upward aesthenospheric flow the first magmatic episode is represented by eocene granitoid plutons and their extrusive carapace that are linearly distributed along the izmir ankara suture zone south of the marmara sea these suites show moderately evolved com positions enriched in incompatible elements similar to subduction zone influenced subalkaline magmas widespread oligo miocene volcanic and plutonic rocks with medium to high k calc alkaline compositions represent the next magmatic episode partial melting and assimilation fractional crystallization of enriched subcontinental lithospheric mantle derived magmas were important processes in the genesis and evolution of the parental magmas which experienced decreasing subduction influence and increasing crustal contamination during the evolution of the eocene and oligo miocene volcano plutonic rocks collision induced lithospheric slab break off provided an influx of aesthenospheric heat and melts that resulted in partial melting of the previously subduction metasomatized mantle lithosphere beneath the suture zone producing the eocene and oligo miocene igneous suites the following magmatic phase during the middle miocene 16 14 ma developed mildly alkaline bimodal volcanic rocks that show a decreasing amount of crustal contamination and subduction influence in time both melting of a subduc tion modified lithospheric mantle and aesthenospheric mantle derived melt contribution played a significant role in the generation of the magmas of these rocks this magmatic episode was attended by region wide extension that led to the formation of metamorphic core complexes and graben systems aesthenospheric upwelling caused by partial delamination of the lithospheric root beneath the western anatolian orogenic belt was likely responsible for the melt evolution of these mildly alkaline volcanics lithospheric delamination may have been caused by peeling off during slab rollback the last major phase of magmatism in the region starting c 12 ma is represented by late miocene to quaternary alkaline to super alkaline volcanic rocks that show oib like geochemical features with progressively more potassic compositions increasing toward south in time these rocks are spatially associated with major extensional fault systems that acted as natural conduits for the transport of uncontaminated alkaline magmas to the surface the melt source for this magmatic phase carried little or no subduction component and was pro duced by the decompressional melting of aesthenospheric mantle which flowed in beneath the atte nuated continental lithosphere in the aegean extensional province this time progressive evolution of cenozoic magmatism and extension in western anatolia has been strongly controlled by the interplay between regional plate tectonic events and the mantle dynamics and provides a realistic template for post collisional magmatism and crustal extension in many orogenic belts

transient hydrological conditions implied by chloride mass balance in southeast australian rivers a robust correlation between electrical conductivity ec values and cl concentrations in river water from southeast australia allows detailed cl fluxes to be calculated from continuous ec and river discharge records many victorian rivers export significantly more cl than is delivered to their catchments by rainfall cl is defined as the mass of cl exported in the rivers relative to that input by rainfall over a multi year period cl 100 indicates that the river exports the same mass of cl as is input by rainfall there is a systematic relationship between catchment type and cl rivers draining cleared plains have cl values between 50 and 750 rivers draining volcanic plains have cl values of 770 1600 whereas rivers with large forested upland catchments have cl values of 50 110 these values are minima as they do not account for cl exported by groundwater from the catchments the calculations are based on long term up to 22 year records that span drought and high rainfall periods the magnitude of cl is far higher than can be explained by errors in the calculations or variability in rainfall and runoff and cl br ratios preclude halite dissolution as a source of cl the excess cl reflects hydrological changes in the catchments land clearing on the cleared plains has caused the rise of regional water tables which results in the export of cl from saline groundwater via increased baseflow to the river systems drainage systems on the volcanic plains are re establishing following impoundment by recent 4 5 ma lava flows cl which accumulated in shallow groundwater around saline lakes and marshes developed on these volcanic plains is now being exported via the rivers the upland catchments have undergone less landscape change and may be in chemical balance the methodology outlined here provides a straightforward assessment of whether catchments are in chemical balance that may in turn indicate whether they are undergoing hydrological changes

late proterozoic and silurian basement units within the serbo macedonian massif northern greece the significance of terrane accretion in the hellenides

slab fragmentation beneath the aegean anatolia transition zone insights from the tectonic and metamorphic evolution of the eastern aegean region abstract slab tearing below western turkey had first order tectonic and magmatic consequences by inducing a lateral gradient of extension in the upper plate and toroidal flow of asthenosphere that affected the typology and distribution of melts at the surface but the coupling mechanisms between the 3d mantle flow at depth and deformation in the upper plate above a slab tear have received little attention so far this paper is focused on the description of the distribution and kinematics of deformation in the eastern part of the aegean sea within the transition zone between the cyclades and the menderes massif which have been little studied by investigating the dodecanese and eastern aegean islands we thus complete the description of the extensional strain field in the overriding plate around the slab tear there extension related to slab retreat and tearing keeps a constant nne ssw direction accommodating the difference in finite rates of extension without localized crustal scale strike slip faults and block rotations above the tear in addition despite the complexity involved in the aegean anatolian orogenic wedge a similar structural position is recognized through the entire region from top to bottom we found that i the lycian units which were exhumed earlier in the late cretaceous ii the higher pressure and higher temperature units i e the upper cycladic blueschist nappe with exception of the vourliotes nappe in samos and finally iii the colder units such as amorgos unit the menderes and its cover before the main menderes metamorphism overprint and the lower cycladic blueschist nappe e g milos folegandros a part of the dodecanese and fourni islands

from palaeotectonics to neotectonics in the neotethys realm the importance of kinematic decoupling and inherited structural grain in sw anatolia turkey abstract in order to asses young i e neotectonic fault kinematics and the relation with plate tectonic processes in sw turkey we focused on the questions 1 what produced the structural grain i e how and when are faults generated 2 what was is the kinematic behaviour of these faults and 3 during which period s were these faults active firstly the distribution of faults has been investigated using a lineament analysis performed on satellite imagery and digital elevation models we define five main tectonic domains in sw turkey 1 and 2 the northern and southern western anatolian extensional provinces 3 the eastern hellenic arc including rhodes island and the submarine anaximander mountains 4 the lycian taurides and 5 the western limb of the isparta angle lineament analysis reveals dominance of three lineament groups i e nne ene and wnw trending in all identified domains variations in the relative importance of lineament groups exist and are attributed to the specific tectonic evolution of each domain a synthesis of recently published field data shows that the onset of activity of related fault groups is neither synchronous nor uniform the structural grain for the neotectonic deformation in sw turkey is formed during the last stage of palaeotectonic deformation stage 1 which is dominated by the onset of the menderes massif exhumation along a top n major detachment the datca break away fault seyitoglu g isik v and cemen i 2004 complete tertiary exhumation history of the menderes massif western turkey an alternative working hypothesis terra nova 16 358 364 and related se ward sliding of the lycian nappes in the footwall of this fault this stage is characterized by spatially variable types of deformation that are delineated by from nw to se the datca fault around the menderes lycian contact zone and the lycian frontal thrust zone respectively the kinematic decoupling along these structures explains the co existence of top n detachment type extension in the western anatolian extensional province and ongoing nappe emplacement and piggy back development in the lycian taurides the decoupling also explains the lateral complexity of deformation associated with later neotectonic deformation from late miocene onward stage 2 nne ssw extension dominated the western anatolian extensional province influenced by combined anatolian extrusion and hellenic subduction roll back contemporaneously bidirectional ese wnw and nne ssw extension controls the lycian taurides due to the effects of hellenic arc expansion superposed on extrusion roll back extension the zone of kinematic decoupling is characterized by structural complexity with local transpressional features during stage 3 post late pliocene the same types of extension prevail in the western anatolian extensional province and the lycian taurides although a third tectonic regime becomes gradually more important this regime is associated with a tectonic escape in the hellenic arc that induced forearc slivers to be sheared of the expanding arc along mostly sinistrally displacing ene trending strike slip zones several of these zones have been identified in the coastal zones of sw turkey either through recent seismicity or field observations and are especially focused in the lycian taurides domain here they form what is classically referred to as the fethiye burdur fault zone which becomes gradually penetrated from the sw by oblique or strike slip zones exemplifying the time transgressive nature of the tectonic escape mechanism zones of kinematic decoupling remain persistent throughout the entire early miocene recent tectonic evolution of sw turkey and explain the existence of differently deforming tectonic domains

effect of anisotropy and groundwater system geometry on seepage through lakebeds 2 numerical simulation analysis abstract the interaction of lakes and groundwater is controlled partly by the geologic framework through which the water flows two interrelated geometric factors of the groundwater system that affect flow are overall geometry of the system and anisotropy of the porous media within the system numerical simulation analysis was made for variations in the coefficient of anisotropy for each of several lake and groundwater settings having different geometric configurations these analyses indicate that for a given geometric setting as the anisotropy of geologic materials decreases seepage from a lake decreases and depth of the local groundwater flow system associated with the lake increases transformation of scale of groundwater systems that have anisotropic media to isotropic equivalents results in a change in the overall geometry because of the different slopes of the water table and lakebed resulting from the scale transformations a series of numerical experiments were made for various geometric configurations for a given anisotropy these analyses indicate that as thickness of the groundwater system decreases relative depth of the local flow system increases and seepage from the lake decreases

discussion on the evolution of the southern menderes massif in sw turkey as revealed by zircon dating journal vol 156 1999 1021 1030 scientific editing by randy parrish erdin bozkurt graham park write loos reischmann 1999 employ geochronological evidence single zircon ages from the augen gneisses of the southern menderes massif sw turkey to conclude that the granitic precursors were intruded between c 521 and 572 ma averaging 550 ma during the late precambrian and early cambrian they claim that this evidence contradicts the views of bozkurt et al 1993 1995 and bozkurt park 1994 who provided the first field evidence for the intrusive nature and tertiary age of the granitic protolith of the gneisses in a complex polydeformed environment like the menderes massif reliance on geochronological evidence alone can be seriously misleading and any viable geological model must satisfy both geochronological and field constraints we would point out that similar old zircon ages are widely known from the literature reischmann et al 1991 loos reischmann 1995 hetzel reischmann 1996 dannat reischmann 1998 hetzel et al 1998 koralay et al 1998 and that it was emphasized in our papers bozkurt et al 1993 1995 bozkurt park 1994 1997 a b that these ages apparently contradict the intrusive contact relations between the metagranites and the structurally overlying metasedimentary envelope loos reischmann confirm the presence of an intrusive contact close to lake bafa but question the intrusive contact relations in the selimiye milas area described by us they claim that the interference of various deformation phases led to the formation of tectonic lenses of the augen gneisses within the schists and vice versa and suggest that it is these structures that we bozkurt et al 1993 1995 interpreted as intrusive contacts however we would emphasise that the intrusive contacts described in

geochemistry and tectonic significance of augen gneisses from the southern menderes massif west turkey the protoliths of mylonitized augen gneisses exposed in the southern sector of the menderes massif west turkey are calc alkaline peraluminous s type late to post tectonic tourmaline and garnet bearing two mica leucogranites they cut and post date the fabrics of the main menderes metamorphism which took place between the early eocene and early oligocene and intrude metamorphic basement rocks comprising the so called palaeozoic schist envelope of the massif they are themselves cut by an extensive network of tourmaline rich dykes chemical mineralogical isotopic and field relations suggest that the granitic protolith crystallized from a boron rich water saturated melt derived from partial melting of metagreywacke in the lower crust during peak barrovian type metamorphism the protolith was probably emplaced during lateorogenic extensional collapse of the thickened crust in west turkey during late oligocene time

lu hf geochronology on cm sized garnets using microsampling new constraints on garnet growth rates and duration of metamorphism during continental collision menderes massif turkey abstract this study shows lu hf geochronology of zoned garnet crystals contained in mica schists from the southern menderes massif turkey selected samples are four 3 5 cm large garnet megacrysts of which several consecutive garnet shells have been sampled with a micro saw and analyzed for dating the results are used to extract growth rates of garnet and also to improve the time constraint for alpine aged overprint of the pan african basement in the menderes massif lu hf ages of the sampled garnet shells are determined by two point garnet only isochrons using the garnets lu depleted rim compositions this yields a consistent decrease of age information from core to rim segments of individual garnet crystals and the calculated isochron ages propose a time frame of growth between 42 6 1 9 and 34 8 3 1 ma major element profiles in the investigated garnets characterize zoning patterns indicative of prograde conditions rayleigh fractionated bell shaped mn and decreasing fe fe mg are recorded by the garnets core to rim compositions therefore the obtained lu hf ages record timing of early prograde growth for the cores of the garnets two of the large garnet crystals also yield isochron ages of 58 83 0 69 and 50 16 0 84 ma in their innermost cores which appear to record an early nucleation event this view however is not in concordance with the observed major element profiles of these garnets and therefore is interpreted with caution termination of the garnet growth period is determined through the calculation of radial growth rates based on the size of the garnets and the lu hf ages obtained for consecutive shells extrapolation of these rates potentially constrains the total duration for garnet growth terminating at 31 6 ma comparison of the growth rates calculated for individual crystals shows a variety of slow and fast growing garnets and similar results have been previously obtained with the rb sr and sm nd isotope systems the new data provides a precise age determination for prograde barrovian metamorphism in the southern menderes massif which so far was placed between 63 and 27 ma on the basis of mica rb sr and ar ar dating this study provides new constraints crucial to the understanding of the tectonic evolution of southwest anatolia and the aegean realm as it yields a shorter outline for alpine aged continental collision

cambrian granitoids in pre alpine basement of crete greece evidence from u pb dating of zircon the pre alpine basement of eastern crete consists of at least three sub complexes which show differences in age and grade of pre alpine metamorphism u pb analyses of zircons of two orthogneisses yielded upper intercepts in the concordia diagram at 511 16 ma chamezi crystalline complex and 514 14 ma myrsini crystalline complex these values are interpreted as protolith ages of the gneisses suggesting that parts of the basement underwent cadomian pan african imprints at the northern margin of gondwana the lower intercept ages are attributed to alpine subduction which led to high pressure low temperature metamorphism t ca 300 c brittle ductile deformation and hydrothermal fluid activity due to pervasive alpine fluid migration the zircons of the chamezi crystalline complex display disturbed zonation and solution resulting in 87 radiogenic pb loss ca and al gain and zr depletion

tectonic transport directions of the lycian nappes in southwest turkey constrained by kinematic indicators abstract the orientation asymmetry and cross cutting relationships of the structures along the contact zone between the lycian nappes and the menderes massif suggest the presence of three deformation phases in the milas region of southwest turkey the first deformation phase d1 is characterized by a ductile deformation with top to the ne sense of shear structural data of the first deformation measured along the uppermost part of the menderes massif and the base of the lycian nappes suggest that the lowermost unit of the lycian nappes was emplaced initially from southwest to northeast onto the menderes massif during the early eocene the second deformation phase d2 is also ductile in nature and is characterized by an e w trending stretching lineation with a bivergent sense of shear which is probably related to the load of the overlying nappes a third deformation phase d3 is characterized by south dipping normal faults with top to the s sense of movement this third deformation phase can be related to southward movement of the lycian nappes along a low angle decollement zone the tectonic contact between the menderes massif and the lycian nappes and their strongly deformed rocks are unconformably covered by approximately flat lying coal bearing early middle miocene sedimentary rocks which constrains the upper time limit for all three deformation phases

reconciling the geological history of western turkey with plate circuits and mantle tomography abstract we place the geological history since cretaceous times in western turkey in a context of convergence subduction collision and slab break off to this end we compare the west anatolian geological history with amounts of africa europe convergence calculated from the atlantic plate circuit and the seismic tomography images of the west anatolian mantle structure western turkish geology reflects the convergence between the sakarya continent here treated as eurasia in the north and africa in the south with the anatolide tauride block atb between two strands of the neotethyan ocean convergence between the sakarya and the atb started at least 95 90 myr ago marked by ages of metamorphic soles of ophiolites that form the highest structural unit below sakarya these are underlain by high pressure low temperature metamorphic rocks of the tavsanli and afyon zones and the oren unit which in turn are underlain by the menderes massif derived from the atb underthrusting of the atb below sakarya was since 50 ma associated with high temperature metamorphism and widespread granitic magmatism thrusting in the menderes massif continued until 35 ma after which there is no record of accretion in western turkey plate circuits show that since 90 ma 1400 km of africa europe convergence occurred of which 700 km since 50 ma and 450 km since 35 ma seismic tomography shows that the african slab under western turkey is decoupled from the african plate this detached slab is a single coherent body representing the lithosphere consumed since 90 ma there was no subduction re initiation after slab break off atb collision with europe therefore did not immediately lead to slab break off but instead to delamination of subducting lithospheric mantle from accreting atb crust while staying attached to the african plate this led to asthenospheric inflow below the atb crust high temperature metamorphism and felsic magmatism slab break off in western turkey probably occurred 15 myr ago after which overriding plate compression and rotation accommodated ongoing africa europe convergence slab break off was accommodated along a vertical ne trending subduction transform edge propagator step fault zone accelerating southwestward slab retreat of the aegean slab the se aegean slab edge may have existed already since early miocene times or before but started to rapidly roll back along the southeastern aegean step in middle miocene times penetrating the aegean region in the pliocene

microstructures in feldspars from a major crustal thrust zone the grenville front ontario canada abstract samples collected across the nw grenville front in ontario canada have been used to document the change in feldspar microstructures produced during shearing under metamorphic conditions that range from upper amphibolite to lower greenschist grade the differential displacement across this 5 km thick section of the grenville front tectonic zone is at least 10 km at upper to mid amphibolite conditions both plagioclase and potassium feldspars behave plastically grainsize reduction occurs through grain boundary migration and or subgrain rotation and produces a core and mantle structure at middle to lower amphibolite grade grain size reduction is accomplished through grain boundary migration at lower amphibolite to upper greenschist grade grain size reduction occurs by the nucleation and growth of new grains with a different composition the abundance of intracrystalline deformation at this grade is inversely proportional to the amount of fine grained matrix in ultramylonite with a high matrix to porphyroclast ratio few intracrystalline strain features occur other than ubiquitous undulatory extinction myrmekite is well developed on the high stress boundaries in k feldspar at upper to mid greenshist conditions feldspars deform mainly by slip on synthetic shear fractures deformation twins undulatory extinction deformation bands and kink bands occur in plagioclase and perthite flames and myrmekite occur principally on high stress boundaries in k feldspar grain size reduction in feldspar is accomplished through cataclasis at middle to lower greenschist facies deformation in feldspars is dominated by antithetic fractures the transition from the dominance of synthetic to antithetic fractures is gradational below lower greenschist grade rocks deform by pervasive cataclasis of all minerals

the 40ar 39ar age of extensional ductile deformation and granitoid intrusion in the northern menderes core complex implications for the initiation of extensional tectonics in western turkey the simav detachment fault in the northern part of menderes core complex in western turkey separates cover sequence rocks with brittle deformation from high grade metamorphic core rocks and young granitoid intrusions the timing of shear zone formation and the intrusion of syn tectonic granitoids is constrained by 40ar 39ar geochronology on muscovite from mylonitic gneiss and biotite from the egrigoz granitoid 40ar 39ar data indicate that mylonitic deformation occurred at 22 86 0 47 ma whilst the cooling age of the granitoid is 20 19 0 28 ma the intrusion and cooling of the egrigoz granitoid occurred between 23 20 ma these data demonstrate that extensional deformation in the northern menderes core complex began before early miocene times and represents an early stage in the tertiary extensional tectonics of western turkey

provenance of sediments during subduction of palaeotethys detrital zircon ages and olistolith analysis in palaeozoic sediments from chios island greece abstract detrital zircon geochronology and analysis of fossiliferous olistoliths from chios island greece are used here to constrain terrane accretion processes and the provenance of crustal sources for sediments during the subduction of a branch of the palaeotethys ocean u pb ages obtained by ion microprobe shrimp ii analyses of detrital zircons from a carboniferous greywacke belonging to the tectonostratigraphic lower unit of chios gave major age groups of 2150 1890 ma 640 540 ma 505 475 ma and 365 322 ma detrital zircons from a permian triassic sandstone yielded prominent age clusters of 2200 1840 ma 1100 910 ma 625 560 ma and 385 370 ma the lack of zircon ages between 1 8 and 1 1 ga in both samples coupled with the occurrence of ca 2 ga old zircons imply a northern gondwana nw africa source the conodont fauna recovered from an orthoceras bearing limestone lens from the carboniferous succession of the lower unit indicates a late silurian age the fauna is typical of the ludfordian polygnathoides siluricus conodont zone the material has a conodont colour alteration index cai of about 1 2 indicating very low grade thermal alteration of less than 100 c the closest localities with similar conodont bearing limestones are to be found in the balkan region and in the istanbul zone of northern turkey the occurrence of orthoceras limestone can be used as an indicator of palaeosource reconstruction our new zircon ages in conjunction with provenance analysis of silurian to lower carboniferous olistoliths strongly suggest that the clastic succession of chios received its detritus from basement rocks of the sakarya microcontinent in western turkey and time and facies equivalents of palaeozoic units from the istanbul zone in northern turkey and the balkan region due to subduction of a branch of palaeotethys close to the southern active margin of eurasia in late palaeozoic times the multidisciplinary approach of this study underlines the importance of terrane accretion during stepwise closure of palaeotethys

handbook of environmental isotope geochemistry vol 1 the terrestrial environment a p fritz and j ch fontes editors elsevier amsterdam 1980 xii 532 pp u s 90 25 dfl 185 00

evolution of late neoproterozoic to early paleozoic tectonic elements in central and southeast european alpine mountain belts review and synthesis abstract late neoproterozoic to early paleozoic cadomian tectonic elements are widespread in the southeastern alpine mediterranean mountain belts with discontinuous exposure extending from the alps to the menderes massif in turkey the sequences include voluminous plutonic island and continental arc successions some ophiolites of variable late neoproterozoic and cambrian to early ordovician ages high to medium grade metamorphic sequences and subordinate metasediments geological and geochronological data suggest that these cadomian elements partly experienced tectonothermal activity including metamorphism and magmatism between ca 650 and 600 ma followed by further i and s type plutonism in an andean type continental margin setting ca between 570 and 520 ma subsequently a major rift zone developed which resulted in continental stretching and subsequent formation of a back arc basin which is dated as late cambrian rifting is followed by oceanic spreading which commenced ca at the cambrian ordovician boundary possibly in a back arc setting this tectonic scenario suggests that alpine mediterranean cadomian tectonic elements were accreted to gondwana during early cadomian events ca 600 650 ma subsequently they were likely part of a long lasting outer subduction zone of gondwana at the margin of a panthalassa type ocean during late neoproterozoic iii and cambrian due to back arc spreading continental pieces started to split off from gondwana ca at the cambrian ordovician boundary

exhumation history of the aydin range and the role of the buyuk menderes detachment system during bivergent extension of the central menderes massif western turkey the central menderes massif western turkey is a prominent example of symmetrical exhumation of a core complex it comprises the bozda and aydin ranges which represent the footwalls of the north dipping gediz detachment and the south dipping buyuk menderes detachment respectively in contrast to the gediz detachment the role of the buyuk menderes detachment during late cenozoic extension and exhumation of the central menderes massif is less well resolved here we present results from structural and geological mapping as well as new fission track and u th he data to show that two low angle normal faults contributed to the exhumation of the aydin range our data indicate that the sustained activity of the buyuk menderes detachment since the early miocene is followed by the onset of faulting along the previously unrecognized demirhan detachment which is situated in the hanging wall of the buyuk menderes detachment in the latest miocene pliocene thermokinematic modelling of cooling ages from the footwalls of the buyuk menderes and demirhan detachments yielded exhumation rates of c 0 5 and c 0 4 km ma 1 respectively apatite fission track ages from the demirhan detachment indicate a slip rate of c 2 km ma 1 during the pliocene high angle normal faulting along the modern buyuk menderes graben commenced in the quaternary supplementary material further results of thermal history modelling are available at https doi org 10 6084 m9 figshare c 4392905

an olistostrome melange belt formed along a suture bornova flysch zone western turkey abstract the bornova flysch zone bfz in western turkey is a regional olistostrome melange belt located between the izmir ankara tethyan suture in northwest and the menderes massif in the southeast the bfz consists mostly of tectonized gravity mass flows the blocks are mesozoic limestone and ophiolite which are enclosed in cretaceous paleocene sheared sandstone and shale the limestone blocks are of two types the first type consists of late triassic to cretaceous shallow marine carbonates the second type has an upper triassic shallow marine section overlain by jurassic to cretaceous pelagic limestones a semi intact part of the platform occurs in the karaburun peninsula and on the island of chios the ophiolitic blocks in the bfz include ultramafic rock gabbro basalt and radiolarian chert of middle triassic to cretaceous in age the formation of the bfz overlaps with the cretaceous subduction and hp lt metamorphism of the northern passive continental margin of the anatolide tauride block this subduction zone was bounded in the west by a strike slip tear fault the bfz formed in a narrow basin between this tear fault and the tethyan ocean the mass flows came from the southeast from the overriding ophiolite and accretionary complex and from the northwest from the uplifted segments of the platform margin this model provides an explanation as why the bfz is unmetamorphosed whereas the equivalent strata in the menderes massif were metamorphosed at depths of over 20 km it also explains the prominence of gravity flows and the southward younging in the bfz and for the apparently anomalous observation that although the tethyan ocean lay to the northwest the ophiolitic blocks are more common on the southeastern part of the bfz regions away from the tear fault such as the karaburun peninsula were least affected by subsidence and deformation during the cretaceous and paleocene

timing of tectonic events in the menderes massif western turkey implications for tectonic evolution and evidence for pan african basement in turkey the menderes massif forms the western of the two large metamorphic culminations within the turkish alpide orogen it has three major lithologic units with a gneissic core at the base and a schist and a marble envelope overlying it successively although relations between them have been largely obscured by the polymetamorphic and structurally complex history of the massif we present a review of the available stratigraphic evidence and combine it with new isotopic ages from the central and southern parts of the massif to constrain the timing of major tectonic events that shaped the massif since the late proterozoic pt3 in the southern part of the massif sensu stricto three episodes of deformation and metamorphism are distinguished whereas in its northern part there are four the first episode occurred at 500 10 ma with intense deformation and metamorphism at high grade amphibolite facies with local anatexis in the central part of the massif the 470 9 ma old now highly deformed tonalitic and granitic intrusions mark the end of this episode on a cambrian reconstruction of continents around the eastern mediterranean the menderes massif forms the southern end of the pan african orogenic collage of northeastern africa and arabia the area of earliest palaeozoic deformation in the menderes may connect with the northwest african orogenic collage along the strike via the bozburun and saricicek diabases arkoses and schists in the center of the karacahisar dome interpreted herein as fragments of a pan african suture the earliest palaeozoic deformations to affect the rocks were probably related to the last pan african collisions and associated postcollisional convergence the southern part of the massif was undeformed from early ordovician to the early later eocene whereas the northern part was deformed metamorphosed and intruded possibly during the late triassic related to the closure of the karakaya marginal basin of palaeo tethys the next major event affecting the whole of the massif was the intense deformation and widespread metamorphism that reached high amphibolite grade in the structurally lower parts and only greenschist grade in the outermost envelope this metamorphism here called the main menderes metamorphism mmm is biostratigraphically constrained between early eocene and early oligocene time rb sr isotopic data show a spread of ages between 60 ma and 25 ma with the greatest number of determinations around 35 5 ma this number is in excellent agreement with the stratigraphic evidence and shows that mmm took place during latest eocene time or at the transition from eocene to oligocene time along the northern border of the massif deformation and metamorphism had already taken place during the late cretaceous in a high pressure low temperature hp lt metamorphic belt northernmost part of menderes massif sensu lato which was then covered by palaeocene molasse the evolution of the hp lt belt was probably related to the obduction of the bozkir ophiolites from the izmir ankara branch of the neo tethys ocean and preceded terminal collision in the evolution of the massif the mmm was a product of the latest palaeocene collision across neo tethys and the consequent internal imbrication of the menderes taurus block that resulted in the burial of the menderes massif area beneath the lycian nappe complex a low grade metamorphic event dated at 10 to 5 ma is interpreted to be related to the extensional deformation in the aegean and western turkey which has been dated stratigraphically to have begun during the tortonian 11 5 ma

a key extensional metamorphic complex reviewed and restored the menderes massif of western turkey article i nfo this paper provides a review of the structure and metamorphism of the menderes massif in western turkey and subsequently a map view restoration of its neogene unroofing history exhumation of this massif among the largest continental extensional provinces in the world is generally considered to have occurred along extensional detachments with a ne sw stretching direction restoration of the early miocene history however shows that these extensional detachments can only explain part of the exhumation history of the menderes massif and that ne sw stretching can only be held accountable for half or less of the

monazite ages and the evolution of the menderes massif western turkey the menderes massif experienced polyphase deformation but distinguishing pan african events from alpine tectono metamorphic evolution and discriminating eocene oligocene shortening from recent extension remain controversial to address this monazite in garnet bearing rocks from the massif s gordes central and cine sections were dated in thin section in situ using the th pb ion microprobe method cambro ordovician monazite inclusions in cine and central menderes massif garnets are 450 m y older than matrix grains monazites in reaction with allanite from the kuzey detachment which bounds the northern edge of the central menderes massif are 17 5 ma and 4 5 1 0 ma the pliocene result shows that dating of monazite can record the time of extension the kuzey detachment might have exhumed rocks a lateral distance of 53 km at a rapid rate of 12 mm year assuming the present 20 ramp dip pliocene monazite crystallization at 450 c and a geothermal gradient of 25 c km assuming an angle of 60 the rate decreases to 5 mm year with the detachment surface at 21 km depth in the pliocene two gordes massif monazites show a similar allanite monazite reaction relationship and are 29 6 1 1 ma and 27 9 1 0 ma suggesting that the cenozoic extension in the gordes massif and possibly the entire menderes massif might have begun in the late oligocene

alpine high p low t metamorphism of the afyon zone and implications for the metamorphic evolution of western anatolia turkey abstract carpholite chloritoid pyrophyllite association occurs widely in the triassic metaclastic rocks of the afyon zone in west central turkey fe mg carpholite is associated with rare aragonite pseudomorphs and glaucophane in marbles and metabasites respectively the afyon zone consists stratigraphically of a pan african basement and an overlying mesozoic cover sequence the pan african basement which shows barrovian type amphibolite facies metamorphism comprises garnet mica schists intruded by sodic amphibole bearing metagabbros and leucocratic metagranites it is unconformably overlain by a continuous metasedimentary sequence extending from triassic to early palaeocene this cover sequence begins with metaconglomerates which pass upwards into phyllites fe mg carpholite occurs within this metaclastic sequence as rosette like crystals in metapelites and fibres in quartz segregations the metaclastic rocks are succeeded by metamorphosed platform carbonates grading into latest mesozoic metamorphosed pelagic limestones which in turn progress up to a late mesozoic early tertiary olistostrome this sequence is tectonically overlain by the blueschists of the tavsanli zone fe mg carpholite bearing assemblages imply temperatures of about 350 c and minimum pressures of 6 9 kbar corresponding to burial depths of about 30 km for the mesozoic passive continental margin sediments and the underlying pan african supracrustal metasediments and metaintrusives the metamorphic rocks of the afyon zone are unconformably overlain by upper palaeocene lower eocene sedimentary rocks indicating a paleocene age for the regional hp lt metamorphism this implies continuous younging of hp lt metamorphism in the anatolides related to northward subduction of the anatolide tauride platform beneath the sakarya zone from north to south this involved the tavsanli zone campanian 80 5 ma the afyon zone palaeocene the menderes massif middle eocene and the lycian nappes late cretaceous eocene all of which were probably derived from the frontal part of the anatolide tauride platform

the wide distribution of hp lt rocks in the lycian belt western turkey implications for accretionary wedge geometry ocean okay monie 1997 okay et al 2002 south of the izmir ankara suture fig 1a other hp lt metamorphic domains have resulted from the late cretaceous northward subduction of the neotethys ocean and subsequent early tertiary collision between the sakarya microcontinent and the anatolide tauride platform 3engor yilmaz 1981 okay et al 2001 these alpine metamorphic terranes form several tectonometamorphic units the late cretaceous blueschist belt of the tav anli zone okay kelley 1994 okay et al 1998 sherlock et al 1999 okay 2002 the recently described hp lt rocks of the afyon zone candan et al 2002 2005 the eocene cycladic blueschists and eclogites of the dilek peninsula region in the westernmost part of the menderes massif area candan et al 1997 oberhansli et al 1998 cetinkaplan 2002 and the hp lt metasediments of the lycian nappes oberhansli et al 2001 rimmele et al 2003a 2005 and the abstract in sw turkey fe mg carpholite has recently been recognized in the basal metasediments of the lycian nappes which overthrust the menderes massif on its southern flank this high pressure low temperature hp lt metamorphic index mineral was widely found in the bodrum peninsula region our new metamorphic and structural data on similar carpholite bearing rocks found farther north in several klippen of the lycian nappes located on top of the menderes massif show that hp lt rocks in sw turkey occur over a distance of 200 km in both north south and east west directions thus indicating a wide hp lt metamorphic belt the deformation pattern from the bodrum peninsula to civril all along the contact between the lycian nappes and the menderes massif reveals the role played by major top to the ne shear zones contemporaneous with exhumation of the lycian hp lt rocks this deformation shows an oblique direction of opposite shear sense relative to the earlier southward translation of the lycian nappes over the menderes massif for which top to the south displacements are preserved in the upper units of the lycian nappes on the bodrum peninsula as well as at the base of the lycian nappe klippen located farther north the widespread distribution of well preserved fe mg carpholite bearing rocks in the lycian nappes has implications for the geometry of the accretionary wedge responsible for hp lt metamorphism in sw turkey

detrital zircon and micropalaeontological ages as new constraints for the lowermost tectonic unit talea ori unit of crete greece the talea ori unit is the lowermost known tectonic unit of crete and the most external part of the hellenides its stratigraphy ranges from late carboniferous to oligocene and outcrops of the lower part are only known in the talea ori mountains central crete in this area a black sandstone at the base of the galinos beds thought to be the oldest formation contains zircons which were dated using the single grain evaporation method the majority of these grains yielded late carboniferous ages variscan while a small group yielded early proterozoic ages the age distribution of these zircons suggests that at the carboniferous permian boundary not much of the older north gondwanan basement was exposed and that a river system carried detrital material from the variscan belt towards the forming neotethyan rift additionally higher up in the stratigraphy benthic foraminifers miliolids were found in clasts from a conglomerate which was so far thought to be of early triassic age epting m kudrass h r leppig u schaffer a 1972 geologie der talea ori kreta n jb geol palaont abh 141 259 285 these miliolids belong to the species hoyenella inconstans michalik j jendrejakova o borza k 1979 some new foraminifera species of the fatra formation uppermost triassic in the west carpathians geol carpath 30 1 61 91 thus attributing a late triassic carnian norian maximal age to this conglomerate the carbonate platform from which the miliolids bearing clasts come is not known the presence to the north of a continuous hemipelagic record from the carboniferous to the triassic phyllite quartzite and tripali units attributed to the palaeotethys realm allows the talea ori unit and its lateral equivalents the ionian zone to be assigned to the westward continuation of the cimmerian block and therefore to the northern margin of the east mediterranean neotethys ocean

intrusion age of pan african augen gneisses in the southern menderes massif and the age of cooling after alpine ductile extensional deformation

an assessment of the seawater effect by geochemical and isotopic data on the brackish karst groundwater from the karaburun peninsula izmir turkey the study area is located in the center of the karaburun peninsula turkey where several karstic springs discharge near the coast 0 2 m above the sea level the most important discharge points are the ildiri and gerence springs groundwater obtained from ildiri springs and several drill wells provide water to the region during the summer periods the electrical conductivity values are between 1900 and 3900 s cm springs are slightly salty and are not used directly as drinking water salinity was observed in the spring waters under natural flow conditions the salinity values of the drillings and springs were measured in dry and wet seasons spring waters have conductivity values between 3000 and 4000 s cm preliminary surveys reveal that seawater contribution to ildiri springs is 6 5 maximum gerence spring waters discharge to the surface from a region very close to the sea the dominant cation is na and the dominant anion is cl conductivity values were between 7000 and 13 000 s cm gerence spring waters discharge to the sea with seawater contributions ratios between 8 5 and 20 3 depending on the seasonal changes while some spring waters discharge 0 5 1 0 m above sea level the rest of them discharge directly into the sea salinization of gerence spring water is higher than the other springs

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

crustal structure of the northern menderes massif western turkey imaged by joint gravity and magnetic inversion in western anatolia the anatolide domain of the tethyan orogen is exposed in one of the earth s largest metamorphic core complexes the menderes massif the menderes massif experienced a two stage exhumation tectonic denudation in the footwall of a north directed miocene extensional detachment followed by fragmentation by e w and nw se trending graben systems along the northern boundary of the core complex the tectonic units of the vardar izmir ankara suture zone overly the stage one footwall of the core complex the northern menderes massif in this study we explore the structure of the upper crust in the northern menderes massif with cross gradient joint inversion of gravity and aeromagnetic data along a series of 10 km deep profiles our inversions which are based on gravity and aeromagnetic measurements and require no geological and petrophysical constraints reveal the salient features of the earth s upper crust we image the northern menderes massif as a relatively homogenous domain of low magnetization and medium to high density with local anomalies related to the effect of interspersed igneous bodies and shallow basins in contrast both the northern and western boundaries of the northern menderes massif stand out as domains where dense mafic metasedimentary and ultramafic domains with a weak magnetic signature alternate with low density igneous complexes with high magnetization with our technique we are able to delineate miocene basins and igneous complexes and map the boundary between intermediate to mafic dominated subduction accretion units of the suture zone and the underlying felsic crust of the menderes massif we demonstrate that joint gravity and magnetic inversion are not only capable of imaging local and regional changes in crustal composition but can also be used to map discontinuities of geodynamic significance such as the vardar izmir ankara suture and the west anatolia transfer zone

crustal thickness variations in the aegean region and implications for the extension of continental crust 1 we installed 5 broadband and 45 short period temporary seismic stations distributed partly as a dense 100 km long n s linear array and partly as a regional network throughout the menderes massif of western turkey in order to study crust upper mantle structure and seismicity in this study we have combined teleseismic waveform data from these stations with data from several permanent seismic stations to determine crustal thickness variations in the aegean region receiver function studies at seven broadband stations using the h stacking method have yielded crustal thicknesses and vp vs ratios over a broad region of the aegean a more detailed crustal image was obtained in the central menderes massif where we applied common conversion point stacking to receiver functions obtained from the n s linear array the results show a general trend of westward crustal thinning from 36 km in central anatolia to 28 30 km in the central menderes massif to 25 km beneath the aegean sea the results also indicate that crustal thinning in the aegean is not uniform in the n s extensional direction the crust is thinner in the central menderes massif 28 30 km of crustal thicknesses and the cycladic massif 25 26 km than in surrounding regions where crustal thicknesses are 32 34 km the long lived elevated moho under the metamorphic core complexes suggests that the lower crust in the aegean region is at least 3 times more viscous than that in the basin and range province where the moho is much flatter

obduction subduction and collision as reflected in the upper cretaceous lower eocene sedimentary record of western turkey late cretaceous early eocene tethyan evolution of western turkey is characterized by ophiolite obduction high pressure low temperature metamorphism subduction arc magmatism and continent continent collision the imprints of these events in the upper cretaceous lower eocene sedimentary record of western anatolia are studied in thirty eight well described stratigraphic sections during the late cretaceous period western turkey consisted of two continents the pontides in the north and the anatolide taurides in the south these continental masses were separated by the izmir ankara neo tethyan ocean during the convergence the pontides formed the upper plate the anatolide taurides the lower plate the arc magmatism in the pontides along the black sea coast is biostratigraphically tightly constrained in time between the late turonian and latest campanian ophiolite obduction over the passive margin of the anatolide tauride block started in the santonian soon after the inception of subduction in the turonian as a result large areas of the anatolide tauride block subsided and became a region of pelagic carbonate sedimentation during the campanian the leading margin of the anatolide tauride block was buried deeply and was deformed and metamorphosed to blueschist facies during campanian times the campanian arc volcanic rocks in the pontides are conformably overlain by shaley limestone of maastrichtian palaeocene age however maastrichtian sedimentary sequences north of the tethyan suture are of fore arc type suggesting that although arc magmatism ceased by the end of the campanian age continent continent collision was delayed until palaeocene time when there was a change from marine to continental sedimentation in the fore arc basins the interval between the end of the arc magmatism and continent continent collision may have been related to a northward jump of the subduction zone at the end of campanian time or to continued obduction during the maastrichtian

processes of late cretaceous to late miocene episodic thrust sheet translation in the lycian taurides sw turkey the lycian taurides of sw turkey consist of an allochthonous mesozoic passive margin succession that was episodically detached from its autochthon and translated southeastwards between latest cretaceous to late miocene times a combination of structural analysis sedimentology palaeontology and geochemistry allows subdivision of this orogenic event into 1 latest cretaceous trench passive margin collision causing ophiolite obduction and detachment of the koycegyiz thrust sheet 2 mid late eocene continent continent collision renewing southeastwards thrusting and causing detachment of the teke dere thrust sheet and yavus thrust sheets 3 miocene extensional collapse of the orogen with southeastwards translation of the allochthon coeval with rift basin formation in the hinterland

stacking of nappes with different pressure temperature paths an example from the menderes nappes of western turkey pressure temperature p t paths have been estimated from metapelitic rocks in the lowermost cine nappe and the directly underlying bozdag nappe of the anatolide belt in western turkey peak metamorphic conditions in the lowermost cine nappe are 670 to 730 c 6 2 to 6 3 kb prograde garnet grt i growth occurred largely before and during the formation of the regional s p a foliation the suffix pa indicates a pre alpine age formation of a second garnet generation grt ii which discordantly overgrew grt i followed at 550 to 620 c 6 4 to 6 5 kb peak metamorphic conditions in the underlying bozdag nappe vary from 480 to 540 c 6 1 to 7 6 kb at the base to 610 to 660 c 8 5 to 10 8 kb at the top of the nappe and attest to an inverted metamorphic field gradient in the bozdag nappe differential thermodynamic modelling gibbs method yielded a prograde path for garnet growth during the formation of s p a because d p a structures formed during prograde metamorphism we relate them to crustal shortening which was associated with a top to the north northeast shear sense in present day coordinates this event caused deformation of the cine and bozdag nappes under different metamorphic conditions we propose that the cine nappe was heated by granitoid intrusions before being emplaced above a foreland unit we speculate that the bozdag nappe belonged to the lower parts of this foreland unit cross cutting relationships of d p a structures with dated granites indicates an age of 540 to 550 ma for this tectonometamorphic event the final juxtaposition of the cine nappe and bozdag nappes and also the inversion of the metamorphic field gradient in the bozdag nappe occurred during greenschist facies conditions during the alpine orogeny in the eocene

geology and geochemistry of the pre early cambrian rocks in the sandikli area implications for the pan african evolution of nw gondwanaland abstract the pre early cambrian sandikli basement complex in western central anatolia comprises a low grade meta sedimentary succession guvercinoluk formation and meta rhyolites intruded by meta quartz porphyry rocks kestel cayi porphyroid suite the guvercinoluk formation consists of alternation of meta siltstones and meta sandstones with olistostromal conglomerates rare black chert and cherty meta dolomite lenses the kestel cayi porphyroid suite is a deformed highly sheared dome shaped rhyolitic body with quartz porphyry rocks quartz porphyry dykes intrude both the volcanic carapace and the meta sedimentary rocks of the guvercinoluk formation both the meta quartz porphyry rocks and meta rhyolites are typically mylonitic with relict igneous textures geochemical data indicate that the felsic rocks of the kestel cayi porphyroid suite are subalkaline and display characteristic features of post collisional i type granitoids the basement complex is unconformably overlain by variegated conglomerates mudstones and arkosic sandstones with andesitic lavas followed by siliciclastic rocks and carbonates that yielded early middle cambrian fossils based on the geochemical characteristics of the felsic rocks of kestel cayi porphyroid suite and the depositional features of the associated sediments it is suggested that the sandikli basement complex is related to a post collisional extension event in nw gondwanaland similar occurrences elsewhere have been related to a transition from continental plate convergence to continental plate divergence along the pan african belt

high pressure metasediments in central turkey constraints on the neotethyan closure history 1 the distribution of oceanic domains and continental blocks in central anatolia remains a challenge in understanding the alpine geodynamic evolution of the tethys realm the consumption of a neotethys oceanic branch at the mesozoic cenozoic boundary welded the central anatolian crystalline complex in central turkey and the anatolide tauride block in western turkey with the northerly eurasian margin whether those two regions constituted a single or two distinct continental masses is still matter of debate high pressure metamorphism has been locally evidenced in the afyon zone which was however defined as a greenschist facies metamorphic zone of the anatolide tauride block since the afyon zone composes a metamorphic equivalent of a continental margin exposed far south of the izmir ankara suture zone this encouraged us to reevaluate its metamorphic evolution in order to better understand the relation between western and central turkey our investigations reveal that the high pressure minerals fe mg carpholite and glaucophane are present in the entire afyon zone which we reconsider as a blueschist facies zone we additionally present a tectonic reconstruction stripping off the postcollisional tectonics it reveals that today s bending of the high pressure belt is consistent with an eocene collision of the anatolide tauride block around the southern edge of the central anatolian crystalline complex we argue that the central anatolian crystalline complex and the anatolide tauride block were two distinct continental masses separated by a neotethyan oceanic stripe the closure of which engendered subduction related metamorphism in the latter and arc volcanism and high grade metamorphism in the former by late cretaceous to early cenozoic

neotethyan closure history of western anatolia a geodynamic discussion this paper addresses the lithosphere scale subduction collision history of the eastern termination of the aegean retreating subduction system i e western anatolia although there is some general consensus on the protracted subduction evolution of the aegean since the early cenozoic at least correlation with western anatolia has been widely debated for more than several decades in western anatolia three main tectonic configurations have been envisaged in the past years to reconstruct slab dynamics during the closure of the neotethyan oceanic realm since the late cretaceous some authors have suggested an aegean type scenario with the continuous subduction of a single lithospheric slab punctuated by episodic slab roll back and trench retreat whereas others assumed a discontinuous subduction history marked by intermittent slab break off during either the campanian ca 75 ma or the early eocene ca 55 50 ma the third view implies three partly contemporaneous subduction zones our review of these models points to key debated aspects that can be re evaluated in the light of multidisciplinary constraints from the literature our discussion leads us to address the timing of subduction initiation the existence of hypothetical ocean basins the number of intervening subduction zones between the taurides and the pontides the palaeogeographic origin of tectonic units and the possibility for slab break off during either the campanian or the early eocene thence we put forward a favoured tectonic scenario featuring two successive phases of subduction of a single lithospheric slab and episodic accretion of two continental domains separated by a continental trough representing the eastern end of the cycladic ocean of the aegean the lack of univocal evidence for slab break off in western anatolia and southward younging hp lt metamorphism in continental tectonic units from 85 70 to 50 ma in the late cretaceous palaeogene period suggests continuous subduction since 110 ma marked by roll back episodes in the palaeocene and the oligo miocene and slab tearing below western anatolia during the miocene

zircon geochronology of basement rocks from the pelagonian zone greece constraints on the pre alpine evolution of the westernmost internal hellenides the pelagonian zone of greece is the westernmost segment of the internal hellenides comprising widespread crystalline basement exposures of granites and orthogneisses we dated these basement rocks in order to identify the major crust forming episodes and to understand the evolutionary history of the area in our study we investigated granites gneisses meta rhyolites and mylonites from the major occurrences of the pelagonian zone we applied single zircon dating techniques such as pb pb evaporation conventional u pb and shrimp the majority of the basement rocks gave permo carboniferous intrusion ages thus emphasizing the importance of this crust forming event for the internal hellenides of greece triassic intrusion ages were obtained however for a meta rhyolite from the western pelagonian zone and two mylonites from the eastern pelagonian zone these ages are interpreted to reflect magmatism accompanying early rifting that led to the subsequent opening of the pindos ocean to the west and the meliata ocean to the east of the pelagonian zone the geochronological results demonstrate that the magmatic episodes during which most of the pelagonian zone crystalline basement formed are predominantly pre alpine in age

stratigraphic and metamorphic inversions in the central menderes massif a new structural model the menderes massif is a large area of dominantly tertiary metamorphic rocks in western turkey it is bordered in the west by the cycladic metamorphic complex with eocene high pressure low temperature hp lt metamorphism in the central menderes the aydin mountains are made up of a thrust stack of eocene age at the base of the thrust stack greenschist facies paleozoic metasediments of the menderes massif form an inverted stratigraphic sequence the barrovian type metamorphism is also inverted with garnet bearing metapelites lying over the lower grade biotite bearing metapelites the p t conditions in the garnet zone are estimated as 530 c and 8 kbar this schist sequence of the central menderes massif is interpreted as the inverted lower limb of a major southward closing recumbent fold with the southern menderes massif representing a section from the near hinge of this fold the paleozoic metamorphic rocks of the central menderes massif are tectonically overlain by gneiss klippen possibly originating from the sheared and southward translated core of the menderes fold lying also tectonically over the paleozoic metamorphic rocks is a major thrust sheet belonging to the cycladic metamorphic complex it consists of garnet micaschist mesozoic marble serpentinite and amphibolitised eclogite although it has a highly sheared internal structure it probably represents an initially coherent sequence that has undergone hp lt metamorphism during the eocene the aydin mountains are dominated by contractional structures with subordinate extensional structures

pb loss patterns in zircons from a high grade metamorphic terrain as revealed by different dating methods upb and pbpb ages for igneous and metamorphic zircons from northern sri lanka abstract we report u pb and 207 pb 206 pb ages for multigrain fractions single grains and grain domains in zircons from highgrade igneous and sedimentary rocks of the vavuniya charnockite province vcp in northern sri lanka using the ionmicroprobe shrimp a new vapour digestion technique vdt and evaporation charnockitic enderbitic and mangeritic gneisses are derived from i type tonalitic syenitic granodioritic and granitic precursors for which the u pb systematics of zircons as determined by shrimp suggest crystallization ages between 1000 and 1100 ma many translucent round and multifacetted zircons in these rocks are not of metamorphic but of igneous origin and acquired their shape through partial zircon dissolution and recrystallization the large majority of zircons exhibit severe and variable pb loss some 540 580 ma ago which we ascribe to granulite grade metamorphism almost immediately followed by local retrogression most of the zircons lost pb from the entire grain with no domains remaining that reflect the original pb isotopic composition it was therefore impossible to obtain meaningful 207 pb 206 pb evaporation ages for such grains and this cautions against use of this method in zircons that experienced severe pb loss however zircons formed during high grade metamorphism apparently retain their primary pb isotopic composition and were dated successfully by the evaporation technique yielding ages between 553 26 and 560 30 ma conventional multigrain analysis and small fractions following vdt for two samples although much more precise than the shrimp data yielded only strongly discordant data points with patterns reflecting variable pb loss these data alone would not have made it possible to obtain reliable primary zircon crystallization ages 207 pb 206 pb evaporation ages for detrital zircons from two garnetiferous gneiss samples of sedimentary origin in the centre of the vcp revealed a maximum age of 1329 18 ma whereas a metaquartzite near the southern margin of the vcp contained zircons with 207 pb 206 pb ages between 1857 14 and 2543 14 ma we interpret the latter rock as belonging to the highland complex which occurs adjacent to the vcp our zircon data in combination with nd model ages milisenda et al 1994 suggest the vcp to be part of the wanni complex a distinct crustal domain in northern sri lanka characterized by relatively young ages in comparison with much older ages in the adjacent highland complex

the oldest rocks of greece first evidence for a precambrian terrane within the pelagonian zone the pelagonian zone in greece represents the westernmost belt of the hellenide hinterland internal hellenides previous geochronological studies of basement rocks from the pelagonian zone have systematically yielded permo carboniferous ages in this study we demonstrate for the first time the existence of a precambrian crustal unit within the crystalline basement of the pelagonian zone the u pb single zircon and shrimp ages of these orthogneisses vary from 699 7 ma to 713 18 ma which identify them as the oldest rocks in greece these late proterozoic rocks which today occupy an area of c 20 100 km are significantly different from the neighbouring rocks of the pelagonian zone they are therefore interpreted as delineating a terrane named here the florina terrane during the permo carboniferous florina was incorporated into an active continental margin where it formed part of the basement for the pelagonian magmatic arc the activity of this arc was dated in this study by single zircon pb pb ages as having taken place at 292 5 ma and 298 7 ma during the alpine orogeny florina together with the pelagonian zone eventually became a constituent of the hellenides geochemically the florina orthogneisses represent granites formed at an active continental margin because of the late proterozoic ages this late proterozoic active continental margin can be correlated to a pan african or cadomian arc as the gneisses contain inherited zircons of late to middle proterozoic age the original location of florina was probably at the northwestern margin of gondwana similar to other gondwana derived terranes such as east avalonia florina approached the southern margin of eurasia during palaeozoic times where it became part of an active continental margin above the subducting palaeotethys these interpretations further indicate that terrane accretion was already playing an important role in the early pre alpine evolution of the hellenides

metamorphic history of the southern menderes massif western turkey metamorphic mineral compositions and textures are integrated with microstructures to test tectonic models for the construction and exhumation of a mid crustal terrane in western turkey the southern menderes massif part of the alpine orogen is composed of a tilted sequence of metasedimentary rocks that structurally overlies orthogneiss garnet biotite equilibria for schists collected along north south traverses consistently indicate temperatures of 430 c for the southernmost structurally highest garnet bearing rocks 500 c for structurally intermediate rocks and 550 c for the structurally deepest rocks near the contact with the orthogneiss there are no detectable discontinuities in metamorphic grade from north to south within the schist unit or between the schist and overlying lower grade and underlying higher grade rocks pressure estimates are less certain geobarometric results for the schists yield p 8 kbar but mineral assemblages and structural data are consistent with lower pressures 6 kbar metamorphic textures and garnet zoning in the menderes schists indicate metamorphism during a single thermal event accompanying development of the main penetrative foliation top to north fabrics formed during folding thrusting and were synkinematic with garnet growth top to south chloritic shear bands truncate the earlier foliation and overprint peak metamorphic assemblages and textures we propose that these metamorphic features and structures indicate synmetamorphic shortening followed by extension during alpine orogenesis

what caused the denudation of the menderes massif review of crustal evolution lithosphere structure and dynamic topography in southwest turkey the deformation of earth s lithosphere in orogenic belts is largely forced externally by the sinking slab but can also be driven by internal delamination processes caused by mechanical instabiliti

whole grain evaporation for 207 pb 206 pb age investigations on single zircons using a double filament thermal ion source a technique has been developed and tested to analyse 207pb 206pb apparent ages by thermal evaporation of radiogenic lead directly from untreated whole zircon grains 0 3 mm the evaporation analyses are performed in the double filament arrangement of a thermal ion mass spectrometer thims the method is a powerful tool to distinguish between different lead components occurring in the same grain because differing activation energies of the competing lead components cause their sequential evaporation from the zircons the evaporation of test samples results in 207pb 206pb apparent ages in good agreement with u pb ages known from literature single zircons from a granite of the marble mountains california yield an age of crystallization of 1 410 30 ma ceylon zircons from heavy mineral bearing gravels yield 560 40 ma as age of crystallization of the pegmatitic gravel sources individuals from a heterogeneous zircon population of a diatexite from the southern schwarzwald sw germany indicate metamorphic zircon formation around 500 ma and the existence of middle proterozoic relics 1 95 0 05 ga

in situ rb sr dating of k bearing minerals from the orogenic akcaabat gold deposit in the menderes massif western anatolia turkey abstract the akcaabat gold deposit is mainly composed of massive arsenopyrite veins in strongly foliated augen gneisses of the cine sub massif in western turkey k bearing minerals from orogenic gold veins were dated by the in situ rb sr method in order to determine the formation age of the akcaabat gold deposit textural relationships between the vein minerals suggest that arsenopyrite k feldspar quartz and muscovite formed in one paragenetic stage native gold native bismuth scorodite and galena were introduced in a later paragenetic stage the isochron derived from k feldspar and muscovite occurring in the veins yielded 31 3 4 7 ma in situ rb sr dating of the same assemblage k feldspar and muscovite in the host rock gave an isochron age of 40 8 3 8 ma 10 ma older than the vein ages and corresponding to peak metamorphism of the regional main menderes metamorphism during the alpine himalayan orogenic event biotite from the host rock gave an isochron age of 28 1 2 2 ma and probably reflects the cooling age homogenization temperatures from fluid inclusions in quartz show that quartz formed at 280 390 but has a dominant mode in the 350 360 temperature interval the age of vein formation was successfully distinguished from the age of the alpine himalayan orogenic event associated with main menderes metamorphism this study demonstrates that in situ rb sr isotopic study can be applied to resolve absolute dating of orogenic deposits in metamorphic complexes

hydrochemical characteristics of groundwater in the zhangye basin northwestern china the zhangye basin located in arid northwest china is an important agricultural and industrial center in recent years rapid development has created an increased demand for water which is increasingly being fulfilled by groundwater abstraction detailed knowledge of the geochemical evolution of groundwater and water quality can enhance understanding of the hydrochemical system promoting sustainable development and effective management of groundwater resources to this end a hydrochemical investigation was conducted in the zhangye basin types of shallow groundwater in the zhangye basin were found to be hco3 hco3 so4 2 so4 2 hco3 so4 2 cl cl so4 2 and cl the deep aquifer groundwater type was found to be hco 3 so 4 2 throughout the entire area ionic ratio and saturation index calculations suggest that silicate rock weathering and evaporation deposition are the main processes that determine the ionic composition in the study area the suitability of the groundwater for irrigation was assessed based on the us salinity laboratory salinity classification and the wilcox diagram in the study area the compositions of the stable isotopes 18o and d in groundwater samples were found to range from 4 00 to 9 28 and from 34 0 to 65 0 respectively these values indicate that precipitation is the main recharge source for the groundwater system some local values indicate high levels of evaporation tritium analysis was used to estimate the ages of the different groundwaters the tritium values of the groundwater samples varied from 3 13 to 36 62 tu the age of the groundwater at depths of less than 30 m is about 5 10 years the age of the groundwater at depths of 30 50 m is about 10 23 years the age of the groundwater at depths of 50 100 m is about 12 29 years for groundwater samples at depths of greater than 100 m the renewal time is about 40 years

the origin and evolution of the menderes massif w turkey a rubidium strontium and oxygen isotope study the menderes massif located in the alpine orogen of western turkey has three litho structural units a basal gneiss core a schist mantle covering the gneiss core and an overlying marble mantle this study reports isotopic data from samples of metasediments and migmatites from the southern type a and of tonalitic to granitic metaigneous rocks from the northern menderes massif type b type a rocks define a rb sr whole rock isochron age of 502 10 ma and an initial87sr 86sr ratio of 0 71174 73 this is interpreted as the age of migmatization type b rocks give a rb sr whole rock isochron age of 471 9 ma with an initial87sr 86sr ratio of 0 70684 25 which we interpret as the intrusion age k white micas from rock type a give an average rb sr mineral age of 56 1 ma which can be interpreted as the formation age of the alpine mineral paragenesis k white micas from rock type b give rb sr mixed ages of 120 230 ma between alpine and pan african orogenies biotites from both rock types yield an average rb sr age of 37 1 ma which is interpreted as an alpine cooling age the oxygen isotope ratios of type a rocks range from 10 4 to 14 6 and of type b from 8 9 to 11 8 the oxygen and strontium isotopic compositions together clearly distinguish rocks of types a and b compositions of type a rocks suggest a crustal origin type b rocks have compositions transitional between those of crustal and mantle derived materials

hydrogeochemical evidence for surface water recharge to a shallow regional aquifer in northern victoria australia abstract the third middle and reedy lakes system in northern victoria is a series of interconnected lakes in which groundwater discharge and recharge occur under seasonal climatic and artificial influences at high lake levels there is a pronounced mounding effect which tends to cause localised perturbation of flow systems and recharge into the uppermost aquifer three hydrostratigraphic units referred to as lower middle and upper are identified beneath the lakes an upward hydraulic gradient exists in the region under the present hydrologic regime despite this hydrochemical and isotopic evidence has demonstrated a fresh water lens beneath reedy lake in the middle and lower aquifers these waters have similar characteristics to the present day water table which is being recharged from the lakes suggesting that the lens represents lake water recharge under a prior hydrologic regime when regional water tables were lower the recognition of this lens has important implications for future management strategies in that it may be possible to implement a more natural wetting drying cycle without the intrusion of saline water into this ecologically sensitive area

forced return flow deep in the subduction channel syros greece we present the results of a detailed structural study in the cycladic blueschist unit at fabrika on syros island greece and discuss their significance for tectonic processes at the subduction int

presence and tectonic significance of cretaceous rudist species in the so called permo carboniferous goktepe formation central menderes metamorphic massif western turkey a schist sequence of the central menderes massif in which lenses of fossiliferous marbles are found is observed in the southern flank of the aydin mountain north of kosk aydin around egrikavak village these rocks have been considered as permo carboniferous in age and are included in the goktepe formation of earlier studies however some rudist species are described from thickly bedded gray marbles that have a concordant contact with the overlying schist sequence although the rudists have been metamorphosed it is observed that some contain fossils are well enough preserved to determine the following rudist fauna hippurites lapeirousei goldfuss hippurites nabresinensis futterer hippurites cf colliciatus woodward this rudist fauna dates the schist sequence as santonian campanian the schist sequence is overlain by a thick tectonostratigraphic pile of orthogneiss which has been interpreted as the pan african metamorphic core of the menderes massif a widespread cataclastic and mylonitic zone is present between the underlying rudist bearing marbles and the structurally overlying orthogneiss sequence the existing kinematic studies in the footwall and hangingwall of this tectonic contact reveal two different phases of deformations a contractional phase followed by an extensional phase during the contractional event which occurred at 36 ma the orthogneiss sequence was thrust faulted northwards over the schist sequence this thrust fault was later reactivated as a low angle normal fault beneath a supradetachment sedimentary basin of early middle miocene age the fossil discoveries of this study and the existing kinematic studies reveal that a new structural model for the central menderes massif in which the tectonometamorphic units form a major southward closing recumbent fold needs to be reviewed

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

evidence against the core cover interpretation of the southern sector of the menderes massif west turkey the menderes massif in western anatolia has been described as a lithological succession comprising a basal precambrian gneissic core of sedimentary origin overlain in sequence by palaeozoic schist and mesozoic cenozoic marble forming the envelope the boundary between core and schist envelope was interpreted as a major unconformity the supra pan african unconformity by contrast our field observations and geochemical data show that around the southern side of besparmak mountain north of selimiye milas the protoliths of highly deformed mylonitized augen gneisses are granitoid rocks intrusive into the adjacent palaeozoic metasedimentary schists the field relationships indicate the age of intrusion to be younger than late permian and there is no evidence for the existence of either an exposed precambrian basement or the supra pan african unconformity in this sector of the menderes massif