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

structural inversion of the tamworth belt insights into the development of orogenic curvature in the southern new england orogen australia abstract the middle to late permian hunter bowen event is credited with the development of orogenic curvature in the southern new england orogen yet contention surrounds the structural dynamics responsible for the development of this curvature debate is largely centred on the roles of orogen parallel strike slip and orogen normal extension and contraction to explain the development of curvature to evaluate the dynamic history of the hunter bowen event we present new kinematic reconstructions of the tamworth belt the tamworth belt formed as a carboniferous forearc basin and was subsequently inverted during the hunter bowen event kinematic reconstructions of the tamworth belt are based on new maps and cross sections built from a synthesis of best available mapping chronostratigraphic data and new interpretations of depth converted seismic data the following conclusions are made from our study i the hunter bowen event was dominantly driven by margin normal contraction east west shortening present day coordinates and ii variations in structural style along the strike of the tamworth belt can be explained by orthogonal vs oblique inversion which reflects the angular relationship between the principal shortening vector and continental arc margin given these conclusions we suggest that curvature around the controversial manning bend was influenced by the presence of primary curvature in the continental margin and that the hastings block was translated along a sinistral strike slip fault system that formed along this oblique with respect to the regional east west extension and convergence direction part of the margin given the available temporal data the translation of the hastings block took place in the early permian asselian and therefore preceded the hunter bowen event accordingly we suggest that the hunter bowen event was dominantly associated with enhancing curvature that was either primary in origin or associated with fault block translation during the early permian this model differs to previously proposed reconstructions where curvature largely formed by orogen parallel strike slip transportation during the hunter bowen event

stratigraphic correlation of the neogene basins in southwestern anatolia regional palaeogeographical palaeoclimatic and tectonic implications abstract the extensional intramontane grabens that formed in southwestern anatolia in the late cenozoic bear the unique tectono sedimentary palaeontological and palynological record of a region that underwent rapid transition from the last compressional pulses of the alpine orogeny to the tectonic phase of orogen collapse and the onset of neotectonic regime the change in tectonic regime was accompanied by regional climatic changes recorded by the sedimentary environments of the basins and evidenced by palaeontological and palynological data the late early to mid middle miocene was characterized by a warm and humid subtropical climate with densely forested wetlands the late middle to late miocene witnessed a change to arid climatic conditions with grass dominated steppe ecosystems the pliocene climate was warm and humid with savannah type open habitats in terms of their stratigraphic development the southwestern anatolian basins form two distinct groups one group is represented by the denizli soke and yatagan basins which commenced their development in the early burdigalian and underwent similar phases of environmental change 1 the burdigalian phase of alluvial environment and redbed deposition 2 the late burdigalian langhian phase of alluvial sedimentation accompanied by the formation of terminal lakes 3 the serravallian middle tortonian phase of the formation of shallow perennial lakes 4 the middle tortonian messinian phase of lake expansion and deepening followed by shrinking and shallowing 5 the pliocene phase of lake expansion and deepening and 6 the erosional quaternary phase of two stage alluvial sedimentation separated by a high relief erosional unconformity the other younger group of tectonic grabens is represented by the karacasu bozdogan cameli and esen basins which commenced their development in the earliest tortonian and underwent common environmental changes 1 the tortonian phase of alluvial environment and redbed deposition coeval with the phase of lake drying in the denizli soke and yatagan basins 2 the messinian phase of the formation of terminal lakes coeval with the re establishment of shallow lakes in the three other basins 3 the zanclean phase of shallow perennial lakes coeval with the expansion and deepening of lakes in the other basins 4 the piacenzian phase of deep lacustrine environments 5 the gelasian phase of shallow lacustrine environments and 6 the erosional quaternary phase of two stage alluvial sedimentation similar as in the other basins in spite of the time offset in their development the two basin groups have been strongly modulated by climate and hence show correlative responses to regional climatic changes despite the time offset in their tectonic development the two basin groups showed correlative environmental changes imposed by regional climatic conditions the basins were environmentally unified by the quaternary alluvial phase of their development in the late cenozoic anatolia was at the crossroads of fauna migration routes between africa asia and europe and the palaeontological data from the southwestern anatolian basins shed more light on this phenomenon the study as a whole contributes to a better understanding of the late cenozoic environmental climatical and biogeographical changes in the eastern mediterranean

structural evolution of the texas orocline eastern australia the texas orocline with a half wavelength of similar to 120 km is the largest and most obvious orocline in the southern new england orogen and is clearly recognised in geological maps and geophysical images in the area of the orocline there is a major unconformity between devonian carboniferous metasedimentary rocks texas beds and the overlying early permian rift related basins detailed structural mapping shows that units both above and below the unconformity are folded around the orocline indicating that at least part of the oroclinal deformation has occurred after the deposition of the early permian rocks in addition early permian 298290 ma granitoids are aligned parallel to the oroclinal structure further indicating that deformation partly occurred during or after the early permian pre oroclinal isoclinal folds f 1 and related axial plane cleavage si are well developed in the texas beds and are curved around the oroclinal structure syn oroclinal structures are characterised by minor kink folds and disharmonic folding f 2 in the core of the orocline a later phase of kink folding corresponding to a similar to n s shortening direction does not seem to be related to the orocline and is interpreted as post oroclinal deformation a secondary penetrative fabric parallel to the axial plane of the orocline was not observed indicating low contractional shortening across the orocline 30 we demonstrate that the observed strain is too low to account for oroclinal bending during dextral transpression as previously proposed we suggest an alternative model involving an initial curved structure probably related to subduction rollback or a pre existing curvature in the palaeomargin of eastern australia which was amplified by dextral transpression and subsequent e w contraction c 2011 international association for gondwana research published by elsevier b v all rights reserved

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

melange genesis and ophiolite emplacement related to subduction of the northern margin of the tauride anatolide continent central and western turkey the tauride anatolide continent stretching for c 900 km across western and central turkey is one of the world s best example of a subducted exhumed passive margin within a collisional orogen twelve widely separated areas were studied and correlated to develop a new plate tectonic model a metamorphosed rifted continental margin of triassic lower cretaceous age tauride anatolide platform is overlain by upper cretaceous cenomanian lower maastrichtian pelagic sediments and then by both tectonic melange subduction complexes and sedimentary melange foredeep gravity complexes the melanges are overthrust by unmetamorphosed ophiolitic rocks commonly peridotites with swarms of diabase gabbro dykes and are underlain by metamorphic soles new geochemical evidence from basaltic blocks in the melange indicates predominantly subduction influenced within plate and mid ocean ridge type settings the dykes cutting the ophiolites were probably intruded during early stage intra oceanic arc genesis the metamorphosed continental margin melanges and ophiolites in the north anatolides are correlated with unmetamorphosed equivalents in the taurides further south e g beysehir and lycian nappes oceanic crust of triassic late cretaceous age formed between the gondwana related tauride anatolide continent in the south and the eurasia related sakarya microcontinent in the north following late triassic early cretaceous passive margin subsidence the continental margin was covered by cenomanian turonian pelagic carbonates c 98 90 ma ophiolites formed in an intra oceanic subduction zone setting in response to northward subduction probably within a two stranded ocean with the inner tauride ocean in the se and the izmir ankara erzincan ocean in the north nw metamorphic soles relate to intra oceanic subduction c 95 90 ma oceanic sedimentary igneous rocks accreted to the advancing supra subduction oceanic slab the tauride anatolide continental margin then underwent diachronous collision with the trench c 85 ma deeply subducted and metamorphosed at hp lt c 80 ma accretionary ophiolitic and exhumed hp lt rocks were gravity reworked into a southward migrating flexural foredeep and progressively overridden c 70 63 ma slices of the upper part of the platform and its margin detached and were thrust southwards as the tauride lycian and beysehir nappes together with regional scale ophiolites the continental margin and melange were simultaneously exhumed during maastrichtian early paleocene 70 63 ma and transgressed by shallow water sediments beginning in the late maastrichtian in the east c 64 ma and the mid late paleocene c 60 ma further west remnant oceanic crust was consumed during early cenozoic time followed by mid eocene 45 40 ma diachronous continental collision and a second phase of regional deformation rather than being progressive there were two stages of collision first upper cretaceous ophiolite emplacement driven by continental margin subduction trench collision and secondly eocene collision of the tauride and sakarya eurasian continents

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

exhumation with a twist paleomagnetic constraints on the evolution of the menderes metamorphic core complex western turkey 1 much remains to be understood about the links between regional vertical axis rotations continental extension and shortening in western turkey miocene vertical axis rotations have been reported that occur simultaneously with the extensional exhumation of the menderes metamorphic core complex which has been related to back arc extension in the eastern part of the aegean back arc in this paper we explore the spatial and temporal relationships between vertical axis rotations in southwestern turkey and extensional unroofing of the menderes massif to this end we provide a large set of new paleomagnetic data from western turkey and integrate these with the regional structural evolution to test the causes and consequences of oroclinal bending in the aegean region the lycian nappes and bey daglari are shown to rotate 20 between 16 and 5 ma defining the eastern limb of the aegean orocline this occurred contemporaneously with the exhumation of the central menderes massif along extensional detachments and after the latest oligocene to early miocene exhumation of the northern and southern menderes massifs exhumation of the latter two was not associated with vertical axis rotations the lower miocene volcanics in the region from lesbos to usak to the north of the central menderes massif underwent a small clockwise rotation insignificant with respect to eurasia this shows that exhumation of the central menderes massif was associated with a vertical axis rotation difference between the northern and southern menderes massifs of 25 30 this result is in excellent agreement with the angle defined by the trends of buyuk menderes and alasehir detachments as well as the angle defined by the regionally curving stretching lineation pattern across the central menderes massif these structures define a pivot point rotation pole for the west anatolian rotations the rotation of the southern domain including the southern menderes massif the lycian nappes and bey daglari must have led to n s contraction east of this pole the eastern limit of the rotating domain is formed by the transpressional couple of the aksu thrust and kirkkavak fault in the center of the isparta angle previously reported clockwise rotations in the volcanic fields near afyon may be the result of distributed n s shortening east of the pivot point the precise accommodation of this shortening history remains open for investigation late oligocene to early miocene extension in the eastern part of the aegean back arc was ne sw oriented and likely bounded by a discrete transform this transform may be associated with an early evolution of the eastern aegean subduction transform edge propagator fault oroclinal bending in the west anatolian region is likely related to a reconnection of the eastern part of the aegean orocline with the african northward moving plate in tandem with roll back in the aegean back arc comparable to a recently postulated scenario for western greece

an active bivergent rolling hinge detachment system central menderes metamorphic core complex in western turkey two symmetrically arranged detachment systems delimit the central menderes metamorphic core complex and define a bivergent continental breakaway zone in the anatolide belt of western turkey structural analysis and apatite fission track thermochronology show that a large east trending syncline within the alpine nappe stack in the central part of the orogen is related to late miocene early pliocene to recent core complex formation the syncline formed as a result of two opposite facing rolling hinges in the footwalls of each of the two detachments back rotation of the syncline limbs suggests that the detachments rotated from an initial dip of 408 608 to a currently shallow orientation of 08 208

petrogenesis and 40ar 39ar geochronology of the volcanic rocks of the usak gure basin western turkiye abstract in spite of much research over the past 30 years the dynamic evolution origin of the volcanism and geometrical stratigraphical relations of the ne sw trending basins in western anatolia are poorly understood the usak gure basin is one of the prominent ne sw trending basins developed on the northern part of the menderes massif core complex three distinct volcanic successions are found in the usak gure basin 1 the beydagi volcanic unit composed of shoshonite latites and rhyolitic lavas followed by dacitic and andesitic pyroclastic deposits 2 the payamtepe volcanic unit composed of potassic intermediate composition lavas latites and trachytes and 3 the karaagac dikes composed of andesite and latite the beydagi volcanic unit occurs in three different ne sw trending volcanic centers beydagi itecektepe and elmadag calderas from southwest to northeast respectively the oldest radiometric ages for the beydagi volcanic unit are from the elmadag volcanic center in the north and range from 17 to 16 ma the data indicate that volcanism was active during the latest early miocene the youngest radiometric age for the beydagi volcanic unit is obtained from the beydagi caldera located 12 ma in the south the data indicate that beydagi volcanism was active in the late middle miocene and migrated from north to south with time 40ar 39ar ages of the payamtepe volcanic unit are restricted to a short period between 16 0 and 15 9 ma volcanic rocks of the usak gure basin are characterized by strong enrichment in lile and lree and depletions of nb ta and ti on morb normalized multi element diagrams geochemical features of the volcanic rocks suggest that they experienced mixing processes between mafic and felsic end members and also fractional crystallization of dominantly plagioclase and pyroxenes from mixed magma compositions crustal contributions to the magma sources may also have occurred during magmatic evolution these processes have resulted in scattered major and trace element variations with respect to increasing silica contents geochemical features of the most mafic samples agree with the results of previous studies from other volcanic areas in western anatolia suggesting that the volcanic rocks in the region were derived from a mainly lithospheric mantle source that had been heterogeneously metasomatized by previous subduction events during convergence between the african and eurasia plates the volcanic activity in the region which developed synchronously with the formation of the menderes massif core complex is best explained by delamination of lithospheric mantle slices that were heterogeneously enriched by previous subduction related processes

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

no need for lithospheric extension for exhuming u hp rocks by normal faulting abstract extensional deformation is commonly considered most important for exhuming rocks from great depths however the necessary space for extending the lithosphere is usually lacking we show that significant exhumation of u hp rocks occurs in extrusion wedges which have a normal fault at their top and a thrust fault at their base the normal fault at the top of an extrusion wedge is a geometric effect and does not result from lithospheric extension therefore the exhumation of u hp rocks in extrusion wedges allows substantial exhumation beneath a normal fault during horizontal shortening and does not cause lithospheric attenuation

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

structural evolution of the usak gure supra detachment basin during miocene extensional denudation in western turkey the usak gure basin is a ne sw trending extensional basin located in the northern part of the menderes massif in western anatolia the usak gure basin contains a lower to upper miocene volcano sedimentary succession that records the unroofing of the metamorphic rocks of the menderes metamorphic core complex we propose a new structural mechanism based on geological mapping and detailed kinematic fault analysis from each of the evolutionary phases we also propose that north to ne dipping low angle detachment surfaces define the basin boundaries and have identified three stages of deformation throughout the miocene the early miocene deformation phase d 2 is characterized by low angle normal faulting simav detachment fault in the supra detachment usak gure basin which marks the initiation of the extensional tectonics during the latest oligocene the middle miocene deformation phase d 3 refers to volcano tectonic activities during accumulation of the inay group the late miocene deformation phase d 4 is related to late miocene tectonic activity widely responsible for deposition of the asartepe formations and uplift of the metamorphic rocks in the usak basin margin in addition we propose that the eastern part of the menderes massif was delimited by the usak mugla transtensional transfer zone from middle miocene time throughout the eastern part of the menderes metamorphic core complex

stratigraphic structural and geochemical features of the ne sw trending neogene volcano sedimentary basins in western anatolia implications for associations of supra detachment and transtensional strike slip basin formation in extensional tectonic setting western anatolia has been the focus of many geological studies of the classical extensional tectonics in the region the ne sw trending neogene volcano sedimentary basins that characterize western anatolia are mainly located on the northern part of the menderes massif a progressively exhumed mid crustal metamorphic unit that has undergone neogene extensional tectonics in the area the ne sw trending basins are the bigadic gordes demirci selendi emet gure and u ak basins although many studies have been carried out in these basins the stratigraphic and tectonic evolution of the ne sw trending volcano sedimentary basins remains controversial and hence different evolutionary models have been proposed by various authors recent studies concluded that there was a close relation in both space and time between the basin formation and the progressive exhumation of the menderes massif in this study we present new stratigraphic geochemical and tectonic observations from the gordes demirci and emet basins and couple them with data from the other ne sw trending basins to produce a tectono stratigraphic evolutionary model for the area gordes basin was opened by strike to oblique slip movements on the basin bounding faults as a result of dextral transtension such that the transtensional gordes basin formed where extension is oblique to the margin that bounded the basin the demirci selendi emet and gure basins have similar stratigraphic and tectonic features and began to develop as supra detachment extensional basins on an early miocene corrugated detachment fault the simav detachment fault sdf in these basins deposition of a middle miocene volcano sedimentary succession was controlled by ne sw trending strike to oblique slip faults which developed as accommodation faults in the hanging wall of a second detachment fault located further south the gediz detachment fault gdf these data suggest that the menderes massif was exhumed through basin formation in the upper plate that arose from successive detachment faulting accommodated by kinematically linked dextral strike to oblique slip motion to the west strike slip faulting is linked to a previously described crustal scale zone of weakness on which the gordes basin was formed the zmir bal kesir transfer zone the ne sw trending basins were also deformed by ne sw trending dextral and nw se trending sinistral strike slip faulting under pure shear during the late miocene and by e w trending dip slip normal faulting in the pliocene quaternary the data indicate that the region has been extended in a not vert similarn s direction since at least the early miocene and that this extension occurred episodically in several phases

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

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

internal tide dissipation mixing and vertical nitrate flux at the shelf edge of ne new zealand an internal tide on the ne shelf of new zealand was observed with a combination of moored temperature loggers and current meters and vertical profiling with a microstructure probe internal tide energy flux across the shelf edge was calculated to be 400 w m with considerable variability driven by the passage of a storm through the region energy associated with the internal tide was significantly greater than the energy of the barotropic tide or of inertial shear dissipation of the internal tide calculated from the energy loss between two of the moorings was estimated to be 15 10 mw m 2 the associated vertical eddy diffusivity was 4 3 x 10 4 m 2 s 1 the microstructure observations indicated internal tide driven vertical diffusivities at the nitracline of 7 x 10 4 m 2 s 1 the observations of vertical eddy diffusivities are combined with measurements of the vertical nitrate gradient to suggest that mixing driven by the internal tide is the dominant mechanism for driving diapycnal nutrient supply during summer the calculated flux of about 12 mmol n m 2 d 1 into the photic zone is suggested to drive significant new subsurface production throughout the summer amounting to a possible contribution to annual new production on the shelf of 100 g c m 2

tectono stratigraphic evolution of the ne sw trending superimposed selendi basin implications for late cenozoic crustal extension in western anatolia turkey abstract selendi basin is located in the eastern part of western anatolia that is the easternmost part of the aegean extensional province in western anatolia crustal extension resulted in exhumation of the mid crustal units the menderes massif synchronously with volcano sedimentary basin formation the stratigraphic and tectonic features of the volcano sedimentary succession reflect the exhumation processes and the modes of extension we present new stratigraphical sedimentological structural and 40ar 39ar age data from the neogene volcano sedimentary fill of the ne sw trending selendi basin the data show that crustal extension in the region occurred in four distinct episodes and accommodated the exhumation of the menderes massif and the basin formation throughout the late cenozoic late oligocene to early miocene detachment faulting the simav detachment fault sdf is attributed to the first episode clastic sedimentation and bimodal volcanism of 20 0 17 5 ma the hacibekir group age was formed in the hanging wall of the sdf during the exhumation of northern menderes massif in the footwall during second episode the menderes collapse occurred and was manifest by formation of the gediz detachment fault gdf during the middle miocene activity on the gdf has resulted in the exhumation of the central menderes massif in the bozdag area during this period the hanging wall of the gdf was dissected by ne sw trending high angle oblique slip cross faults and accommodated clastic to lacustrine carbonate deposition and syn sedimentary bimodal volcanism of 16 15 ma the inay group the third episode is represented by formation of nw se trending sinistral and ne sw trending dextral strike to oblique slip faults and associated dip to oblique slip normal faults during the late miocene indicating that the area was deformed under a strike slip tectonic regime the faults localized alluvial sedimentation the kocakuz formation and basaltic volcanism of 7 8 ma the kabaklar basalt in the selendi basin the last episode commenced by the start of the plio quaternary this period is represented by the currently active n s extensional tectonic regime that resulted in the formation of e w trending high angle normal faults that controls the present day e w trending graben type basin formation e g gediz and simav grabens and the quaternary 1200 60 ka basaltic volcanism

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

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

a comparison of geodetic and finite strain pattern in the aegean geodynamic implications abstract a comparison of the active strain pattern of the aegean constrained by global positioning system measurements and the oligo miocene finite strain field shows some striking similarities in terms of direction and rates of extension the geometry of extension at crustal scale is also very similar with north dipping normal faults connecting near the brittle ductile transition to shallow north dipping shear zones this pattern of extension is not significantly modified by the recent extrusion of the motion of anatolia and aegea the persistence over more than 25 myr of the same pattern of extension suggests that the cause for extension resides within the aegean lithosphere gravitational collapse allowed by extensional boundary conditions after 30 ma slab retreat is the primary cause for post orogenic extension in the aegean and western anatolia

lower to middle devonian radiolarian assemblages from the gamilaroi terrane glenrock station nsw australia abstract five radiolarian assemblages are described from a stratigraphic succession of lower to middle emsian eifelian devonian rocks in the gamilaroi terrane nsw australia these assemblages are in stratigraphic order the helenifore laticlavium circulaforma admissarius n sp helenifore sp a protoholoeciscus hindea and ceratoikiscum regalinodus n sp assemblages four new species of ceratoikiscid ceratoikiscum calvum n sp ceratoikiscum paragyium n sp ceratoikiscum regalinodus n sp and circulaforma admissarius n sp are described a lower emsian limestone near the middle of the stratigraphic section provides age constraints the four assemblages in strata overlying the limestone are estimated using inferred sedimentation rates to be upper emsian to eifelian biostratigraphically useful ceratoikiscid forms are abundant indicating that the potential for further refining a lower to middle devonian radiolarian biostratigraphy is high

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

bivergent extension in orogenic belts the menderes massif southwestern turkey the central menderes massif is characterized by an overall dome shaped foliation pattern and a north northeast trending stretching lineation the asymmetry of shear bands and quartz c axis fabrics on either side of the structural dome demonstrate a top to thenorth northeastshearsenseinthenorthernpartandatoptothesouth southwestshear sense in the southern part of the submassif i e a bivergent downdip movement this suggests a symmetric collapse of the alpine menderes orogenic belt along two extensional shearzones conjugateshearbandsandsymmetricquartzc axisfabricsintheeast trendingtransitionzonedemonstrateacoaxialdeformationbetweenthetwoextensiondomains bivergent extension in the menderes massif is in contrast to asymmetric extension in the aegeansea here thestill activehellenicsubductionzoneevolvedfromanadvancingplate boundary associated with crustal thickening into a retreating plate boundary in oligocene miocene time southward rollback of the subducting plate during continuous northward subduction allowed asymmetric top to the north northeast extension in the back arc region during the exhumation of the cycladic core complexes in western turkey the arrival of the thick continental crust of the menderes massif halted subduction and probably caused the symmetric collapse of the massif because the high potential energy of the thickened crust was no longer supported by subduction

a pulsed extension model for the neogene recent e w trending alasehir graben and the ne sw trending selendi and gordes basins western turkey abstract we have developed a significant body of new field based evidence relating to the history of crustal extension in western turkey we establish that two of the ne sw trending basins in this region the gordes and selendi basins whose sedimentary successions begin in the early miocene are unlikely to relate to late stage alpine compressional orogeny or to e w extension of tibetan type grabens as previously suggested we argue instead that these basins are the result of earlier late oligocene low angle normal faulting that created approximately n s scoop shaped depressions in which clastic to lacustine and later tuffaceous sediments accumulated during early mid miocene time separated by elongate structural highs these basins were later cut by e w trending plio quaternary normal faults that post date accumulation of the neogene deposits in addition we interpret the alasehir gediz graben in terms of two phases of extension an early phase lasting from the early miocene to the late miocene and a young plio quaternary phase that is still active taking into account our inferred earlier phase of regional extension we thus propose a new three phase pulsed extension model for western turkey we relate the first two phases to roll back of the south aegean subduction zone and the third phase to the westward tectonic escape of anatolia

reconstructing subduction polarity through the geochemistry of mafic rocks in a cambrian magmatic arc along the gondwana margin ordenes complex nw iberian massif in the allochthonous complexes of the nw iberian massif the upper units have been interpreted as a section of a peri gondwanan magmatic arc active from middle cambrian to early ordovician times the main plutonic bodies intruding the arc metasediments are the monte castelo gabbronorites and the corredoiras orthogneisses which include minor metagabbronorite bodies both dated at ca 500 ma the geochemical features of monte castelo metagabbronorites indicate a tholeiitic affinity with negative nb anomaly its 143nd 144nd ratios are high 0 5143119 0 513019 whereas initial 87sr 86sr ratios are low 0 702562 0 703174 with positive endi values 7 8 to 5 4 the geochemistry of corredoiras metagabbronorites indicates a calc alkaline affinity also with negative nb anomaly low 143nd 144nd 0 512575 0 512436 and high initial 87sr 86sr 0 705082 0 706684 endi values ranging between 0 65 and 1 83 in the end versus age diagram monte castelo samples show compositions equivalent to the contemporaneous depleted mantle corredoiras metagabbros have much lower endi values compared with monte castelo samples with older model ages ranging between 1165 and 1291 ma suggesting contamination of the original mafic mantle derived magmas with an older continental crust these geochemical features can be linked to the setting of a mature volcanic arc in which monte castelo metagabbros were located close to the trench while corredoiras metagabbros would be in a relatively distant position from the trench thus indicating subduction polarity

controls on back arc crustal accretion insights from the lau manus and mariana basins abstract together the lau manus and mariana basins encompass a broad range of conditions of back arc basin development marine surveys have determined the tectonic setting and reconnaissance scale geophysical and geochemical properties of the extension axes in these basins we review these data to examine crustal accretion characteristics in the back arc setting in each basin magmatism is enhanced in spreading centres near the arc volcanic front but decreases becoming deficient in axes further from the arc in the lau and manus basins the axes extend far behind the arc and develop typical mid ocean ridge mor like characteristics we propose that these variations are controlled by the subducting slab which shapes composition and flow within the mantle wedge water released from the slab lowers the mantle solidus and increases in concentration toward the volcanic arc spreading centres near the arc advect the hydrated mantle material enhancing melt production slab induced flow carries melt depleted mantle material back beneath the basin where it mixes with ambient mantle spreading centres further from the arc advect this mantle mixture and produce thinner than normal crust far from the arc spreading centres advect essentially mid ocean ridge basalt morb source mantle and their characteristics are mor like thus in addition to spreading rate effects on mantle melting that predominate at mors in back arc basins the subducting slab introduces additional systematic effects

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

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

miocene sedimentary evolution of the ne sw trending selendi and gordes basins w turkey implications for extensional processes abstract western turkey is one of the classic regions for the study of extensional processes in a recent interpretation the regional metamorphic basement the menderes massif was exhumed related to large scale extensional processes possibly during latest oligocene time regional scale ne sw trending basins including the gordes and selendi basins were created associated with this exhumation the ne sw trending basins are seen as regional scale corrugations 10 15 km across in the surface of an extensional detachment orientated parallel to the direction of extension the detached upper plate is represented by erosional remnants of unmetamorphosed tethyan ophiolitic melange we describe and interpret the gordes and selendi basins separately and then show that their sedimentary facies and evolution are very similar basal coarse alluvial fan deposits accumulated after extensional removal of the upper plate these basal sediments rarely exposed were rotated by up to 50 probably as a result of local extension or transtension later during the early miocene the gordes and selendi basins were infilled by a generally fining upward succession derived from the south based on palaeocurrent evidence coarse alluvial fan deposition was followed by the deposition of finer grained alluvial deposits from braided streams flowing northwards over a topographically subdued flood plain later deposition was within shallow ephemeral lakes after a possible change to a moister climate calc alkaline magmatism was initiated with the fall out of fine grained silicic ash followed by coarser grained tuff derived from local magmatic centres during early pliocene time the basins were dissected by e w extensional faults associated with the establishment of the modern pattern of westward drainage to the aegean sea we use the assembled sedimentary evidence to test alternative tectonic models for miocene basin formation in western turkey our preferred tectonic model emphasises the importance of deposition in regional basins created by exhumation of metamorphic basement that was previously assembled during early tertiary closure of the tethys ocean

devonian intra oceanic arc rift sedimentation facies development in the gamilaroi terrane new england orogen eastern australia abstract silurian devonian rocks within the gamilaroi terrane part of the new england orogen of eastern australia provide a well preserved on land example of the development of an intra oceanic arc rift ten sedimentary facies represent different phases in the evolution of the gamilaroi rift and are typified by predominantly volcaniclastic conglomerates and mudstones with minor sandstones all of which were deposited by debris flows and turbidity currents subordinate facies include limestones crystal rich volcaniclastic sandstones volcanic breccias and olistostromes the facies are distributed throughout a succession of six lithostratigraphic units each of which represents a distinct phase in the history of the arc rift felsic volcanic and volcaniclastic rocks at the base of the section represent part of the original arc and are overlain by volcaniclastic sandstones and mudstones deposited within an arc basin lower devonian emsian limestones underwent rapid subsidence concurrent with an influx of volcaniclastic sediments indicating initiation of rift related faulting a thick conglomerate succession was deposited rapidly on a debris apron system adjacent to the steep sided rift walls overlying tuffaceous mudstones indicate a decrease in clastic input later in the history of the rift basin thick intervals of massive and pillowed basalts at the top of the succession indicate a major period of volcanism within the rift oceanic island arc rift sequences are characterised by highly variable sedimentary facies distribution facies distribution over the 400 km extent of the gamilaroi terrane is also highly variable modern arc rift zones are divided into a series of smaller separate elongate basins providing an explanation for the high facies variability observed in the field

base of the kiaman its definition and global stratigraphic significance defining and dating the base of the kiaman the long period of reverse polarity that spans the time from the late carboniferous to the middle permian have proven difficult in an attempt to do this an integrated stratigraphic paleomagnetic and geochronologic study was undertaken in carboniferous rocks in the northern tamworth belt of the new england orogen eastern australia new paleomagnetic measurements at 145 horizons sites in the new england orogen of eastern australia provide an accurate record of the late namurian to westphalian geomagnetic field they have high unblocking temperatures satisfy tilt conglomerate and slump tests and show excellent agreement between a wide variety of igneous and sedimentary rock types indicating that magnetism was acquired at or soon after deposition magnetite and to a lesser degree hematite are the carriers of magnetization the record is contained in sequences of glaciogene sediments and arc derived volcano sedimentary units folded into broad structures in the late permian to triassic new isotopic dates for the volcanic units indicate ages from 321 to 306 ma late namurian to westphalian magnetizations are steeply inclined downward reversed polarity in the southern hemisphere except within the clifden formation of the rocky creek syncline where a change from normal to reverse polarity referred to as the wanganui reversal records the onset of the kiaman superchron integrating complex stratigraphic isotopic and paleomagnetic data we correlate the wanganui reversal to the top of n6 in the joggins section nova scotia canada and estimate that its age is between 318 and 316 ma further work may substantiate a younger normal zone in australia that would support a slightly younger age but within these limits these considerations indicate that the wanganui reversal occurs in the late namurian marsdenian and after the time of the mississippian pennsylvania boundary the mean direction of magnetization of the upper carboniferous australian sequences is declination d 195 3 inclination i 76 9 25 95 3 1 with a paleopole at 51 9 s 141 2 e 95 5 7 and a paleolatitude of 65 0 5 6 s p 0 05 this paleolatitude is consistent with the glacial origin of some of the sedimentary units

tectonic denudation of a late cretaceous tertiary collisional belt regionally symmetric cooling patterns and their relation to extensional faults in the anatolide belt of western turkey t hermochronological data reveal that the late cretaceous tertiary nappe pile of the anatolide belt of western turkey displays a two stage cooling history three crustal segments differing in structure and cooling history have been identified the central menderes metamorphic core complex represents an inner axial segment of the anatolide belt and exposes the lowest structural levels of the nappe pile whereas the two outer submassifs the g ordes submassif to the north and the ci ne submassif to the south represent higher levels of the nappe pile a regionally significant phase of cooling in the late oligocene and early miocene affected the outer two submassifs and the upper structural levels of the central menderes metamorphic core complex in the northern part of the g ordes submassif cooling was related to top to the nne movement on the simav detachment as the apatite fission track ages show a northward younging trend in the direction of movement on this detachment in the ci ne submassif relatively rapid cooling in late oligocene and early miocene times may have been related to top to the s extensional reactivation of the basal thrust of the overlying lycian nappes the second phase of cooling in the anatolide belt is related to pliocene to recent extension resulting in the formation of the central menderes metamorphic core complex in the inner part of the anatolide belt core complex development caused the formation of supra detachment graben which document the ongoing separation of the central menderes metamorphic core complex from the outer submassifs

turbulent nitrate fluxes in the amundsen gulf during ice covered conditions 3 2 5 10 3 m 2 s 1 and decreased exponentially to a depth of 50 m below which it was roughly constant at the background value kb 3 2 5 1 0 6 m 2 s 1 t he nitracline centered around 62 m depth was subject to an eddy diffusivity close to the background value kb and the mean diffusive nitrate flux across the nitracline was fnit 0 5 0 3 0 8 mmol m 2 d 1 these observations are compared with other regions and the role of vertical mixing on primary production in the amundsen gulf is discussed citation bourgault d c hamel f cyr j e tremblay p s galbraith d dumont and y gratton 2011 turbulent nitrate fluxes in the amundsen gulf during ice covered conditions geophys res lett 38 l15602 doi 10 1029 2011gl047936

observations of turbulent mixing and hydrography in the marginal ice zone of the barents sea 1 measurements of hydrography currents microstructure shear and temperature were made at ice drift stations in the marginal ice zone miz of the northern barents sea highly variable mixing regimes were observed within and below the pycnocline elevated turbulent dissipation 5 15 10 7 w kg 1 was associated with strong vertical shear between the surface layer and the subsurface currents as well as strong tidal flow over shallow topography dissipation in the pycnocline was enhanced at stations with strong wind forcing during drifts under relatively calm wind and away from strong fronts and abrupt topography station mean dissipation values were up to a factor 50 lower and double diffusion contributed significantly to the vertical heat flux where hydrography favored diffusive layering independent measures of turbulent length scale from density overturns compared well with those inferred from the dissipation measurements the variability of dissipation was better captured using a scaling by shear suggested for shelves rather than shear variance models appropriate to the deep open ocean sufficiently resolved patches of enhanced temperature microstructure used in combination with dissipation measurements suggest mixing efficiency of rf 0 2 for patches stable to double diffusion comparable to the conventional upper bound of rf 0 17 mixing efficiency for double diffusive convection favorable cases is found to be significantly larger rf 0 36 water mass modification and fluxes of nutrients and dissolved carbon were found to have large local variability in accordance with the observed variability of vertical mixing in the miz

geochemistry of lau basin volcanic rocks influence of ridge segmentation and arc proximity side scan sonar imaging of the central lau basin sw pacific has revealed a central lau spreading centre clsc propagating southwards at the expense of an eastern lau spreading centre elsc with a small intermediate lau spreading centre ilsc forming a relay between the two volcanic rocks sampled along these spreading centres and from two adjacent seamounts are glassy to fine grained pillow lavas and sheet flows of basalts ferrobasalts and andesites the evolved rocks are mostly confined to the propagating tip of the clsc and can be explained by a high rate of cooling relative to magma supply as invoked for magma genesis at propagating ridges elsewhere compared with equivalent rocks from the eastern pacific the most evolved members of the clsc suite require similarly high degrees 90 of fractional crystallization from their basaltic parents fractional crystallisation cannot however account for the compositional differences between clsc and elsc lavas whereas the composition of the clsc lavas lies just within the compositional spectrum of typical n morb the elsc lavas are distinctly enriched in alkali and alkaline earth elements reach oxide and apatite saturation at lower fe ti and p concentrations and generally show greater vesicularity despite slightly greater depths of eruption all indicative of a water rich subduction component they also have lower contents of ni sc na and fe and higher contents of si at a given mgo concentration that indicate a more depleted and more hydrous mantle beneath the elsc compared with the clsc these results provide further evidence that beneath the central lau basin the source composition changes progressively from morb type to island arc tholeiite type as the subduction zone is approached both eastwards from the clsc to elsc and southwards along the elsc to the valu fa ridge they also indicate that the composition of the subduction component may vary systematically away from the arc with th lree ba rb and h as h2o all present close to the arc only ba rb and h2o present at intermediate distances and just h2o perceptible at the furthest distances

a younger thinner arctic ice cover increased potential for rapid extensive sea ice loss 1 satellite derived estimates of sea ice age and thickness are combined to produce a proxy ice thickness record for 1982 to the present these data show that in addition to the well documented loss of perennial ice cover as a whole the amount of oldest and thickest ice within the remaining multiyear ice pack has declined significantly the oldest ice types have essentially disappeared and 58 of the multiyear ice now consists of relatively young 2 and 3 year old ice compared to 35 in the mid 1980s ice coverage in summer 2007 reached a record minimum with ice extent declining by 42 compared to conditions in the 1980s the much reduced extent of the oldest and thickest ice in combination with other factors such as ice transport that assist the ice albedo feedback by exposing more open water help explain this large and abrupt ice loss

complete tertiary exhumation history of the menderes massif western turkey an alternative working hypothesis the main exhumation of the menderes massif western turkey occurred along an originally n dipping datca kale main breakaway fault that controlled depositions in the kale and the gokova basins during the oligocene early miocene interval the isostatically controlled upward bending of the main breakaway fault brings the lower plate rocks to the surface in the early miocene e w trending n and s dipping graben bounding faults fragmented the exhumed dome shaped massif the development of half grabens by rolling master fault hinges has allowed further exhumation of the central menderes massif after the pliocene high angle normal faults cut all of the previous structures this model suggests that the menderes massif is a single large metamorphic core complex that has experienced a two stage exhumation process

devonian volcanics in the new england orogen tectonic setting and polarity abstract the tectonic setting of the devonian rocks in the new england orogen has been the subject of considerable debate and controversy for many years our studies reveal that they have formed in intra oceanic island arc and back arc basin bab settings based on th yb nb yb ba la and zr y ratios further many of the samples that formed in a bab have a mixture of morb and arc like characteristics a few are almost entirely morb like the arc like features are believed to be due to the presence of a subduction component in the basaltic magma the amount of which is controlled by the distance from the arc those samples with morb like compositions are thought to have originated at spreading centres the compositions of late devonian basalts become more arc like to the west suggesting a west facing polarity based on the tectonic setting and spatial relationship of late devonian sequences we propose that two subduction zones existed during the late devonian one dipping west beneath the lachlan orogen the other dipping east beneath a rifted intra oceanic arc obduction of this intra oceanic arc over the continental margin of the lachlan orogen in the latest devonian at approximately 375 ma led to the development of a new west dipping subduction zone oceanward and commencement of continental arc magmatism

late orogenic crustal extension in the northern menderes massif western turkey evidence for metamorphic core complex formation the simav metamorphic core complex of the northern menderes massif western turkey consists of a plutonic tertiary and metamorphic precambrian core footwall separated from an allochthonous cover sequence hanging wall by a low angle ductile to brittle extensional fault zone i e detachment fault the core rocks below the detachment fault are converted into mylonites with a thickness of a few hundred metres two main deformation events have affected the core rocks the first deformational event d1 was developed within the precambrian metamorphic rocks the second event d2 associated with the tertiary crustal extension includes two distinct stages stage one is the formation of a variably developed ductile mylonitic deformation d2d in metamorphic and granitic core rocks under greenschist facies conditions the majority of the mylonites in the study area have foliations that strike nnw to nne and dip sw to se stretched quartz and feldspar grains define the mineral lineation trending sw ne direction and plunging gently to sw the kinematic indicators indicate a top to ne sense of shear stage two formation of brittle deformation d2b that affected all core and cover rocks d2b involves the development of cataclasites and high angle normal faults an overall top towards the north sense of shear for the ductile mylonitic fabrics in the core rocks is consistent with the n s regional extension in western turkey

the algodoes amphibolite tonalite gneiss sequence borborema province ne brazil geochemical and geochronological evidence for palaeoproterozoic accretion of oceanic plateau back arc basalts and adakitic plutons abstract field relationships geochemistry and u pb zircon and sm nd whole rock geochronology are used to constrain the genesis of palaeoproterozoic massive amphibolites and orthogneisses of the algodoes sequence central ceara domain northeastern brazil the 2236 55 ma old algodoes amphibolites show trace element geochemical signature and positive e nd t values similar to phanaerozoic oceanic plateau basalts and less often to back arc basalts the amphibolites are intruded by tonalitic to quartz dioritic gneisses of the cipo unit which were dated at 2160 2170 ma and 2130 ma neodimium isotope data and whole rock geochemistry for these gneisses show they are akin to juvenile arc plutonics of the adakitic suite the likely occurrence of palaeoproterozoic plateau basalts and arc plutonics in this part of northeastearn brazil render comparisons with similar terranes elsewhere in south america and africa which in turn indicate a significant contribution of accretionary orogens in the early assembly of the columbia supercontinent

irreversible nitrate fluxes due to turbulent mixing in a coastal upwelling system 1 detailed and repeated measurements of nitrate across the oregon shelf made coincident with turbulence measurements reveal the importance of cross isopycnal mixing via turbulence in providing nitrate to the upper water column spatial distributions of vertical gradients and turbulent fluxes in the oregon coastal ocean reveal variability that could not have been resolved with traditional sampling approaches nitrate rich near bottom waters are drawn up the shelf during upwelling and back down the shelf during downwelling continuous turbulent mixing in the bottom boundary layer increases nitrate on intermediate isopycnals by several m toward the shelf this increased nitrate is consistent with measured turbulent flux of nitrate of o 0 1 mol m 2 s 1 for a period of 3 days roughly the timescale for changes in the wind and hence to the upwelling circulation our flux estimates are consistent with high biomass nutrient replete incubation based primary productivity estimates in this area and suggest that turbulent vertical nitrate transport plays a significant role in supporting the high productivity seen here offshore of 30 m depth we estimate the irreversible transport of nitrate from nitrate rich near bottom waters to be about 25 of the rate at which it is provided by upwelling the total irreversible transport is greater by some unknown amount when we consider the transport inshore of 30 m depth we suggest that the onshore transport of offshore water whether deep water during upwelling or surface water during relaxation forces the juxtaposition of strong gradients and mixing regimes such that turbulent vertical fluxes are consistently elevated in the shoreward reaches of the coastal ocean

repetition of the mount morgan stratigraphy and mineralization in the dee range northeastern australia implications for exploration conodont data from the banded mine sequence of the mount morgan gold copper deposit shows the sequence to be late eifelian early middle devonian the same age as the banded mineralised sequence of the upper part of the mount warner volcanics of the dee range 14 km to the southeast data underpinning this correlation are presented the very similar lithostratigraphy and now demonstrated chronologic identity of the mineralized sequences in the two areas implies that the mount warner volcanics is a repetition of the banded mine sequence of the mount morgan area a single system of stratigraphic nomenclature may thus be utilized for both areas most importantly this conclusion enhances the prospectivity of the comparatively underexplored mount warner volcanics repetitions of the world class mount morgan volcanic hosted massive sulfide orebody might thus be anticipated to occur in the mount warner volcanics conodont data from units unconformably overlying the mount warner volcanics banded mine sequence formerly mine corridor sequence and the mount morgan trondhjemite which intruded and metamorphosed the mount morgan orebody imply that the mount morgan trondhjemite was intruded within an interval of six or seven conodont zones on the order of 6 or 7 m y or perhaps more after the deposition of the ore hosting banded mine sequence

soft sediment deformation structures in late albian to cenomanian deposits sao luis basin northern brazil evidence for palaeoseismicity soft sediment deformation structures from the alc ntara formation late albian to cenomanian sao luis basin northern brazil consist of 1 contorted structures which include convolute folds ball and pillow structures concave up paths with consolidation lamination recumbently folded cross stratification and irregular convolute stratification that grades into massive beds 2 intruded structures which include pillars dykes cusps and subsidence lobes and 3 brittle structures represented by fractures and faults displaying planes with a delicate ragged morphology and sharp peaks these structures result from a complex combination of processes mostly including reverse density gradients fluidization and liquefaction reverse density gradients promoted by differential liquefaction associated with different degrees of sediment compaction led to the genesis of convolute folds more intense deformation promoted the development of ball and pillow structures subsidence lobes and sand rolls which are attributed to denser and thus more compacted less liquefied portions that sank down into less dense more liquefied sediments irregular convolute stratification that grades into massive beds would have formed at periods of maximum deformation the subsidence of beds was accompanied by lateral current drag and fluid escape from water saturated sands in addition the fractures and faults record brittle deformation penecontemporaneous with sediment deposition all these mechanisms were triggered by a seismic agent as suggested by a combination of criteria including 1 the position of the study area at the edge of a major strike slip fault zone that was reactivated several times from the albian to the holocene 2 a relative increase in the degree of deformation in sites located closer to the fault zone 3 continuity of the deformed beds over large distances several kilometres 4 restriction of soft sediment deformation structures to single stratigraphic intervals bounded by entirely undeformed strata 5 recurrence through time and 6 similarities to many other earthquake induced deformational structures

provenance history of a carboniferous gondwana margin forearc basin new england fold belt eastern australia modal and geochemical constraints abstract the visean stephanian myall trough eastern australia formed part of a forearc basin to the east of a magmatic arc situated along the palaeo pacific margin of gondwana petrographic modal whole rock geochemistry and mineral phase chemistry of sandstones siltstones conglomerates and associated igneous rocks provide a consistent and coherent data set which indicate sediment derivation from a magmatic arc of predominantly silicic volcanic composition the low quartz modes of the sandstones the largely volcanic origin of lithic fragments and the overall high sio 2 content of the siliciclastic sediments and igneous rocks require the arc source to be largely dacitic to rhyolitic in composition the predominance of vitric type highly siliceous volcanic rocks lithic fragments suggests a source composed largely of silicic pyroclastics the presence of potassium feldspar as well as the presence of biotite as the principal detrital ferromagnesian phase in the sandstones suggest a source of medium to high k tholeiite composition the high trace element abundances of relatively immobile elements such as zr la ce v nb y and th and corresponding high th u zr y la y la sm ratios and low zr th zr nb la th and ti zr ratios for both the igneous rocks and derived siliciclastic sediments in the myall trough also require a high k and or strongly medium k arc source a lack of temporal or spatial trends in the data indicate that the magmatic arc remained of uniform composition throughout the 25 ma interval of strata preserved within the trough the provenance history of the myall trough requires accumulation along an andean type continental margin rather than an intra oceanic arc outboard of the gondwana margin

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

thermochronologic evaluation of postcollision extension in the anatolide orogen western turkey 1 to better understand the driving mechanisms behind the transition from collision to extension in a convergent orogen data from multiple low temperature thermochronometers were obtained from the simav detachment fault sdf the earliest developed major extensional structure recognized in the western anatolide orogen of western turkey twenty two zircon fission track ft 26 apatite ft 12 apatite u th he ages and 26 apatite ft track length analyses are presented the data establish that the sdf was a major extensional fault active between 25 and 19 ma the coincidence in timing of magmatism with cessation of sdf activity implies the detachment became locked owing to doming induced by magma emplacement zircon ft ages away from the influence of miocene magmatism record rapid footwall cooling between 25 and 21 ma at a slip rate of up to 15 km myr and demonstrate that active ductile deformation along the sdf migrated northward with time apatite ft ages from the footwall of the sdf are spatially invariant over 100 km and consistently 2 3 myr younger than the zircon fission track ages from the same samples these data are consistent with a regional but relatively rapid erosion linked cooling phase that removed 2 3 km of overburden following cessation of sdf activity but before deposition of sedimentary rocks on the detachment surface at 16 4 ma postcollision extension of the anatolide orogen with development of the sdf can be best explained as the result of postcollision magmatism and thermal weakening of the crust inducing the extensional reactivation of an earlier major out of sequence thrust

kinematic development and paleostress analysis of the denizli basin western turkey implications of spatial variation of relative paleostress magnitudes and orientations paleostress orientations and relative paleostress magnitudes stress ratios determined by using the reduced stress concept are used to improve the understanding of the kinematic characteristics of the denizli basin two different dominant extension directions were determined using fault slip data and travertine fissure orientations in addition to their stratigraphically coeval occurrence the almost exact fit of the s2 and s3 orientations for the ne sw and nw se extension directions in the late miocene to recent units indicate that these two extension directions are a manifestation of stress permutations in the region and are contemporaneous this relationship is also demonstrated by the presence of actively developing ne sw and nw se elongated grabens developed as the result of ne sw and nw se directed extension in the region moreover stress ratios plots indicate the presence of a zone of major stress ratio changes that are attributed to the interference of graben systems in the region it is concluded that the plotting of stress orientations and distribution of stress ratios is a useful tool for detecting major differences in stress magnitudes over an area the boundaries of which may indicate important subsurface structures that cannot be observed on the surface q 2005 elsevier ltd all rights reserved

evolution of the miocene sedimentary fill of the gediz graben sw turkey abstract the gediz graben is a continental extensional basin filled with miocene to recent sediments the evolution of the graben can be expressed in terms of two phases i miocene half graben phase and ii post miocene graben phase the miocene half graben phase was governed by the southern margin structure evolution of which significantly controlled the stratigraphic variability in the basin alluvial fluvial and lacustrine systems developed in the graben as a function of distance to the southern margin thus alluvial deposits with coarse grained facies dominate the southern margin and grade into finer fractions of fluvial and or lacustrine deposits to the north this depositional architecture repeated three times during the miocene and deposited alasehir caltilik and gediz formations these formations depict distinct thickness and grain size decrease from south to north to emphasize the half graben configuration for the favour of the southern margin the post miocene graben phase started with the faulting of the northern margin this resulted in relatively balanced partitioning of the subsidence between the two margins although the preceding asymmetry was inherited by the graben sediment influx became bipolar and alluvial fan systems developed along the both margins

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

multistage exhumation of the menderes massif western anatolia turkey structural analyses along selected transects across the menderes massif and incorporation of existing data have resulted in a synthetic cross section across southwestern turkey the tectonic interpretation has been combined with 40ar 39ar laser probe experiments on two syn kinematic white mica populations which respectively predate and overprint documented early miocene deformational fabrics our results indicate that the regional extension had initiated by eocene oligocene times a 36 2 ma 40ar 39ar age derived from white mica which formed during a regionally observed northward directed tectonic transport suggests that the extension was contemporaneous with the tectonic emplacement of mid crustal continental basement alternatively the age may relate to the regional cooling of the basement sequence and thus postdates the tectonic emplacement in the latter scenario the analysis fails to solve the present ambiguity on the pan african or alpine affinity of the northward directed transport further exhumation of basement rocks is characterized by a dominant displacement along the north dipping gediz detachment at the northern margin of the massif which developed under ductile conditions in the early miocene by partial exploitation of older zones of weakness which originated from an earlier phase of basement emplacement youngest semi ductile activity along the gediz detachment has been recorded as having a 7 1 ma 40ar 39ar age derived from syn kinematic white mica in the top of the detachment following the initiation of the ductile gediz detachment an antithetic semibrittle and south dipping buyuk menderes detachment had developed in the center of the massif which together with the gediz detachment accommodated further doming of the central part of the menderes massif and controlled the architecture of the surrounding supradetachment basins

isotopic evidence for rapid continental growth in an extensional accretionary orogen the tasmanides eastern australia the trace element signature of earth s continental crust resembles that of arc lavas but the continents may have formed during ancient igneous pulses that are hard to reconcile with supra subduction zone magmatism we explore the role of coupled arc back arc accretionary processes in crust generation by considering the tectonic context of whole rock nd isotope and zircon hf o isotope data from igneous rocks of the australian tasmanides 515 230 ma which is thought to have evolved by the repeated opening and closure of sediment filled back arc basins behind a long lived subduction zone the significance of this process for continental crust formation has yet to be evaluated from an isotopic perspective granitic rocks in this area define striking secular end ehf 18o trends that correlate with the pattern of deformational events and register changes in magma source during tectonic activity these trends reveal that juvenile magmatic input was enhanced during extensional back arc rifting episodes that immediately followed crustal thickening suggesting a relationship between slab rollback and continental growth interaction between juvenile magma and sedimentary units deposited during a preceding back arc rifting cycle was integral to the formation of stable continental material this highlights the importance of back arc environments for both the generation and differentiation of continental crust the juvenile component within the tasmanide igneous rocks increased from the cambrian to the triassic consistent with a diminished input from cratonderived metasedimentary material as the subduction zone migrated outboard of the gondwana margin subduction zone retreat formed large tracts of new crust in eastern australia at comparable rates to crust generation at modern island arcs providing a mechanism for rapid continental growth at convergent margins using isotopic tracers to link tectonic evolution and crust generation in modern and ancient orogens can lead to a better understanding of the geodynamic controls on planetary differentiation

gamilaroi terrane a devonian rifted intra oceanic island arc assemblage nsw australia the gamilaroi terrane comprises part of the new england orogen of eastern australia and contains devonian strata preserving evidence of their development in a variety of arc related environments radiolarian studies provide new and more precise constraints on stratigraphy and together with geochemistry allow development of a new model for evolution of the terrane a diverse suite of volcaniclastic sedimentary rocks intercalated with regionally extensive extrusive and high level intrusive meta felsic igneous rocks of low k and calc alkaline volcanic affinity is present these rocks constitute the oldest in situ volcanic rocks in the gamilaroi terrane and are similar to those found in modern intra oceanic volcanic island arc settings basaltic intrusions and lavas occur at higher stratigraphic levels major and trace element compositions together with relatively flat chondrite normalized ree distributions resemble those from rocks formed in modern intra oceanic island arc rift zones the close spatial association of these rock types together with an absence of continent derived detritus is consistent with interpretation of development of the gamilaroi terrane in an intra oceanic island arc which experienced local rifting this interpretation is a departure from previous models for the new england orogen which interpret the gamilaroi terrane as a forearc basin that developed above a long lived cambrian to permian west dipping subduction zone fringing the continental margin of gondwana by analogy with modern arc continent collision zones in which crust between colliding continents and island arcs is preferentially subducted beneath the approaching arc we suggest that oceanic crust intervening between gamilaroi terrane and gondwana was subducted eastwards under the western margin of the gamilaroi terrane arc during a latest devonian collision event the gamilaroi terrane was obducted onto the gondwana margin this resulted in subduction flip and subsequent development of an east facing continental margin arc system on top of the gamilaroi terrane