kinematic reconstructions and magmatic evolution illuminating crustal and mantle dynamics of the eastern mediterranean region since the late cretaceous the relationship between subduction dynamics and crustal deformation in the mediterranean region has been recently studied using three dimensional 3d numerical models such models require however a detailed information concerning the past geological evolution we use stratigraphic petrologic metamorphic structural paleomagnetic and magmatic data to build new kinematic reconstructions of the eastern mediterranean region since the late cretaceous using the principle of non rigid domains the motions of the 56 deforming domains defined in this work are calculated based on published paleomagnetic rotations the directions and amounts of displacement on crustal scale shear zones and the burial and exhumation histories of the main metamorphic units extracted from these reconstructions paleotectonic maps and lithospheric scale cross sections illustrate that the present day subduction zone has been continuously retreating southward since the late cretaceous and has accreted several small continental domains in the process we find evidence for two back arc related extensional events 1 slow extension along the balkans and the pontides in the late cretaceous while the trench was long and linear and 2 faster extension in the rhodope aegean west anatolian region since the eocene oligocene rapid rotation of the hellenides between 15 and 8 ma probably indicates a slab tearing event below western anatolia that could have further accelerated this extensional kinematics spatial distribution and the geochemical signature of magmatic centers integrated in these reconstructions allow us to trace mantle related processes revealing the deep dynamics that controls both the magma genesis and the crustal deformation

diagnostic features and field criteria in recognition of tectonic sedimentary and diapiric melanges in orogenic belts and exhumed subduction accretion complexes abstract multiple episodes of deformation during the tectonic evolution of orogenic belts and ancient subduction accretion complexes cause obfuscation of primary block in matrix fabric of melanges and thereby making the recognition of their tectonic sedimentary or diapiric origin difficult here we present a comprehensive overview and synthesis of a diverse set of field based stratigraphic and structural criteria which are at the base of geological mapping rules to differentiate between various melange types developed by disparate geological processes and mechanisms we first define the current concepts of melange and melange nomenclature and describe the most diagnostic features of tectonic sedimentary and diapiric melanges at different scales we discuss some of the main issues complicating the application of these diagnostic criteria such as i similarities between the block in matrix fabric of different melange types formed in partially lithified sediments at shallow structural levels ii transformation of fabric elements with increased depth due to tectonic reworking and recrystallization processes iii significance of exotic versus native blocks in melange matrix and iv age relationships between blocks and matrix in a melange we introduce two additional criteria in approaching these complexities and in recognizing different processes of polygenetic melanges formation in the field when primary diagnostic fabrics were reworked by multiple deformational events these new criteria are based on i the coherence between lithological compositions of melange components blocks and matrix and characteristics and tectonic evolution of the geodynamic setting of their formation tectonic environment criterion and ii specificity and kinematic coherence in the distribution of deformation between blocks and the matrix deformation criterion the discussed diagnostic criteria can be applied to all field based investigations of melanges and broken formations in orogenic belts and exhumed subduction accretion complexes around the world regardless of their location age and tectonic history

kinematics of a former oceanic plate of the neotethys revealed by deformation in the ulukisla basin turkey kinematic reconstruction of modern ocean basins shows that since pangea breakup a vast area in the neotethyan realm was lost to subduction here we develop a first order methodology to reconstruct the kinematic history of the lost plates of the neotethys using records of subducted plates accreted to former overriding plates combined with the kinematic analysis of overriding plate extension and shortening in cretaceous paleogene times most of anatolia formed a separate tectonic plate here termed anadolu plate that floored part of the neotethyan oceanic realm separated from eurasia and africa by subduction zones we study the sedimentary and structural history of the ulukisla basin turkey overlying relics of this plate to reconstruct the tectonic history of the oceanic plate and its surrounding trenches relative to africa and eurasia our results show that upper cretaceous oligocene sediments were deposited on the newly dated suprasubduction zone ophiolites 92 ma which are underlain by melanges metamorphosed and nonmetamorphosed oceanic and continental rocks derived from the african plate the ulukisla basin underwent latest cretaceous paleocene n s and e w extension until 56 ma following a short period of tectonic quiescence eo oligocene n s contraction formed the folded structure of the bolkar mountains as well as subordinate contractional structures within the basin we conceptually explain the transition from extension to quiescence to shortening as slowdown of the anadolu plate relative to the northward advancing africa anadolu trench resulting from collision of continental rocks accreted to anadolu with eurasia until the gradual demise of the anadolu eurasia subduction zone

birth death and resurrection the life cycle of suprasubduction zone ophiolites 1 suprasubduction zone ssz ophiolites display a consistent sequence of events during their formation and evolution that suggests that they form in response to processes that are common to all such ophiolites this sequence includes the following 1 birth which entails the formation of the ophiolite above a nascent or reconfigured subduction zone this stage is typically characterized by the eruption of arc tholeiite lavas and the formation of layered gabbros and sheeted dike complex 2 youth during which is continued melting of refractory asthenosphere depleted during birth occurs in response to fluid flux from the subducting slab with extensional deformation of the older plutonic suite eruption of refractory lavas and the intrusion of wehrlite pyroxenite 3 maturity with the onset of semistable arc volcanism typically calc alkaline as the subduction zone matures and stabilizes and the intrusion of quartz diorite and eruption of silicic lavas and 4 death which is the sudden demise of active spreading and ophiolite related volcanism which in many cases is linked to collision with an active spreading center and the onset of shallow underthrusting of the buoyant spreading axis expressed as dikes and lavas with oceanic basalt compositions that crosscut or overlie rocks of the older suites 5 resurrection with emplacement by obduction onto a passive margin or accretionary uplift with continued subduction the early stages 1 3 may be diachronous and each stage may overlap in both time and space the existence of this consistent progression implies that ophiolite formation is not a stochastic event but is a natural consequence of the ssz tectonic setting

structure and geochemistry of tethyan ophiolites and their petrogenesis in subduction rollback systems suprasubduction zone ssz ophiolites in orogenic belts represent oceanic crust generation in subduction rollback cycles during the closing stages of basins prior to terminal continental collisions mantle flow and slab rollback result in one or more episodes of arc splitting and basin opening producing a collage of protoarc and forearc oceanic lithosphere in suprasubduction zone settings the jurassic cretaceous ssz tethyan ophiolites in the eastern mediterranean region i e mirdita pindos troodos kizildag oman generally have penrose type oceanic crust and contain well developed sheeted dike complexes indicative of magmatic extension beneath narrow rift zones during their seafloor spreading evolution igneous accretion of these ssz tethyan ophiolites involved upper plate extension and advanced melting of previously depleted asthenosphere in host basins showing a progressive evolution from morb like to iat island arc tholeiite to boninitic extremely refractory protoarc assemblages however there are some distinct differences in the geochemical evolution of these tethyan ophiolites that appear to have resulted from variations in their subduction zone geodynamics whereas a major part of the kizildag and troodos lavas shows island arc affinity similar to their counterparts in the pindos and mirdita ophiolites a significant component of the oman lavas indicates morb affinity and the majority of the kizildag and oman data plot within the mantle array between n morb and e morb on the nb yb th yb discriminant diagram furthermore the troodos and oman lavas do not show any particular th enrichment in their multi element patterns suggesting that fluid melt input from subducted sediments was not that significant in generation of their magmas although all ophiolites exhibit geochemical features indicating increased subduction influence during the melt evolution of their younger extrusive sequences and dike intrusions as evidenced by their negative nd values their overall characteristic trace element patterns seem to have been strongly affected by the maturity of the subduction systems in which they developed

ophiolite obduction pulses as a proxy indicator of superplume events abstract a major new synthesis of ophiolite geochronology and map of global phanerozoic distribution indicates that previously noted pulses of ophiolite obduction can be linked to superplume related tectonism a marked cyclicity is evident in obduction ages obtained from minerals in ophiolite metamorphic soles and obduction related minor intrusions this episodicity is in phase with periods of predominantly uniform polarity of the geomagnetic field formation of massive carbon rich deposits sea level highstands and formation of large flood basalt provinces all generally considered to be superplume proxy indicators a key to interpreting ophiolite obduction as a further proxy is the mid cretaceous superplume associated ocean margin compressional deformation during this event thermal rejuvenation and increased buoyancy of ocean lithosphere caused arc terrane collision marginal basin shoaling back arc basin closure and ophiolite obduction convergent margins were placed in compression with increased coupling between subducting and overriding plates resulting in major ocean margin deformation being directly datable and tectonically and petrologically distinctive makes ophiolite assemblages of considerable use for identifying superplume events

the tectonic history of the nigde kirsehir massif and the taurides since the late mesozoic paleomagnetic evidence for two phase orogenic curvature in central anatolia the nigde kirsehir massif known also as the central anatolian block is bordered by the sutures of the neotethys ocean the massif suffered several deformation phases during and after the consumption of the surrounding oceans and the post collisional events of the continental pieces of anatolia in latest cretaceous to miocene previous paleomagnetic studies on the nigde kirsehir massif and its surroundings displayed either insufficient data or have claimed large rotations and or remagnetization in order to understand the tectonic history of the nigde kirsehir massif and its adjacent blocks we have sampled 147 different sites in the age range of upper jurassic to miocene from the nigde kirsehir massif throughout its w sw and e se boundaries and the central southeastern taurides the results display that except the limestones in central taurides all rocks examined carry a primary magnetization among these an important finding is that rotations between the massif and the central eastern taurides indicate an oroclinal bending with counterclockwise rotation of r 41 1 7 6 in the se and clockwise rotation of r 45 9 9 3 in the central taurides from upper cretaceous rocks with respect to the african reference direction paleomagnetic rotations in the se taurides are compatible with the vergent direction of the thrusts generated from consumption of the intra tauride ocean prior to post collisional convergence between taurides and the massif in the central taurides it has been shown that the clockwise rotation of 45 9 9 3 started in middle eocene because of a remagnetization in upper creataceous limestones the deformation was linked to the final closure of the southern neotethys and the collision between the african and eurasian plates in the nigde kirsehir massif counterclockwise rotation up to 25 5 7 3 is recognised during middle eocene and interpreted in terms of block rotation together with the taurides after the miocene a counterclockwise rotation of 16 8 3 9 along the eastern taurides shows that this area was mostly affected by the westward movement of anatolia despite the nigde kirsehir massif and its sw w area the central taurides which is recognised as stable with counterclockwise rotation less than 10

the berit transect of the tauride thrust belt s turkey late cretaceous early cenozoic accretionary collisional processes related to closure of the southern neotethys abstract we report on an integrated study of a critical segment of the tauride thrust belt in se turkey berit area units related to two sutures are exposed in the northerly and southerly parts of the area studied in the north the upper cretaceous binboga melange reflects the closure of a northerly mesozoic oceanic basin in the south contrasting units document the closure of the southern neotethys in the south the berit or goksun ophiolite formed as an incipient oceanic arc within the southern neotethys during the late cretaceous c 90 ma intercalated amphibolite granulite facies rocks may record a dismembered metamorphic sole an underlying meta sedimentary meta volcanic unit is interpreted as accreted continental rift and oceanic seamount lithologies the berit ophiolite was accreted to the tauride active continental margin to the north around 85 ma and was then intruded by calc alkaline granites c 70 85 ma northerly margin units were exhumed and covered by shelf carbonate sediments during latest cretaceous early cenozoic time northward subduction during the mid cenozoic c 45 ma resulted in back arc extension along the tauride active margin and subduction influenced volcanism possibly controlled by slab roll back during oligocene early miocene time the southern neotethys closed and the tauride active margin was telescoped to create the present south vergent thrust stack this was accompanied by mass wasting of the advancing allochthon to form sub aqueous frontal olistostromes the arabian platform was over ridden by mid miocene time followed by left lateral strike slip along the east anatolian fault zone as anatolia began to escape westwards towards the aegean sea

petrology geochemistry and tectonics of the sabzevar ophiolite north central iran abstract the sabzevar ophiolite is a highly dismembered ophiolite complex located along the northern boundary of the central iranian microcontinent cim and is one of the internal iranian group of ophiolites and colored melanges the igneous rocks of this complex consist of peridotites harzburgite dunite and lherzolite serpentinite minor pyroxenite gabbros and a volcanic sequence that exhibits a wide range of composition from basalts and basaltic andesites to rhyodacite dacites rhyolites and basanites sedimentary rocks include a variety of upper triassic to lower cretaceous deep and shallow marine rocks these include pelagic fossiliferous carbonates that are mixed with the pillow basalt and basaltic andesite as interlayers or exotic blocks ranging in size from 10 to 100 m also present are extensive units of radiolarian chert which are interbedded within the basalts and basaltic andesites a combination of petrographic observations and analyses of incompatible trace elements and rare earth elements indicates the presence of at least four different types of extrusive rocks in the sabzevar ophiolite the geochemical data clearly identifies some of the extrusive rocks to have formed from three distinct types of basaltic melts i the group 1 basaltic rocks which formed from an initial melt with n morb like lree depleted chemical signatures and are petrogenetically related to the gabbros ii group 2 basaltic rocks which have e morb chemical signatures and iii group 3 basaltic rocks with lree enriched signatures and incompatible trace element patterns that suggest an island arc affinity the data also suggest that the gabbros and the group 1 basaltic rocks are petrogenetically related and produced by fractionation of plagioclase and to a lesser extent clinopyroxene and hornblende similar to other studied iranian ophiolites e g khoy band e zeyarat dar anar neyriz kermanshah and baft the results from the sabzevar ophiolite demonstrate the presence of relics of mid ocean ridge basalt morb like signatures in the extrusive units of neo tethyan ophiolites and suggests that the fossil oceanic lithosphere preserved in these ophiolites developed at an oceanic spreading center in addition the sabzevar ophiolite contains other volcanic rocks that have non morb like geochemical signatures e g within plate island arc the differences between these geochemical signatures could be a result of a differing upper mantle composition or different degrees of partial melting of the same upper mantle the presence of sizable nb anomalies in the extended rare earth element ree patterns for andesites and the group 3 basalts is characteristic of volcanic arc magmas or possibly are products of the ascending magma that was modified by crustal contamination the presences of the basanites and the silica undersaturated rocks could be attributed to extrusive activity following ophiolite emplacement plate reconstructions suggest that rocks of the sabzevar ophiolite were part of the tethyan oceanic crust that was formed during rifting of a narrow but deep seaway that separated the cim from the eurasian plate the ophiolite was emplaced during northeast dipping subduction i e closure of this segment of the tethyan seaway sabzevar ocean

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

oceanic crust generation in an island arc tectonic setting se anatolian orogenic belt turkey a number of late cretaceous ophiolitic bodies are located between the metamorphic massifs of the southeast anatolian orogenic system one of them the goksun ophiolite northern kahramanmaras which crops out in a tectonic window bounded by the malatya metamorphic units on both the north and south is located in the ew trending nappe zone of the southeast anatolian orogenic belt between goksunand afsin northern kahramanmaras it consists of ultramafic mafic cumulates isotropic gabbro a sheeted dyke complex plagiogranite volcanic rocks and associated volcanosedimentary units the ophiolitic rocks and the tectonically overlying malatya keban metamorphic units were intruded by syn collisional granitoids 85 ma the volcanic units are characterized by a wide spectrum of rocks ranging in composition from basalt to rhyolite the sheeted dykes consist of diabase and microdiorite whereas the isotropic gabbros consist of gabbro diorite and quartzdiorite the magmatic rocks in the goksunophiolite are part of a co magmatic differentiated series of subalkaline tholeiites selective enrichment of some lil elements rb ba k sr and th and depletion of the hfs elements nb ta ti zr relative to n morb are the main features of the upper crustal rocks the presence of negative anomalies for ta nb ti the ratios of selected trace elements nb th th yb ta yb and normalized ree patterns all are indicative of a subduction related environment all the geochemical evidence both from the volcanic rocks and the deeper levels sheeted dykes and isotropic gabbro show that the goksun ophiolite formed during the mature stage of a suprasubduction zone ssz tectonic setting in the southern branch of the neotethyan ocean between the malatya keban platform to the north and the arabian platform to the south during late cretaceous times geological geochronological and petrological data on the goksun ophiolite and the baskil magmatic arc suggest that there were two subduction zones the first one dipping beneath the malatya keban platform generating the baskil magmatic arc and the second one further south within the ocean basin generating the goksun ophiolite in a suprasubduction zone environment

geodynamic significance of granitoid magmatism in the southeast anatolian orogen geochemical and geochronogical evidence from goksun afsin kahramanmaras turkey region in southeast anatolia there are number of tectonomagmatic units in the kahramanmaras malatya elazig region that are important in understanding the geological evolution of the southeast anatolian orogenic belt during the late cretaceous these are a metamorphic massifs b ophiolites c ophiolite related metamorphics and d granitoids the granitoids i e goksun afsin in kahramanmaras dogansehir in malatya and baskil in elazig intrude all the former units in a ne sw trending direction the granitoid in goksun afsin kahramanmaras region is mainly composed of granodioritic and granitic in composition the granodiorite contains a number of amphibole bearing mafic microgranular enclaves of different sizes whereas the granite is intruded by numerous aplitic dikes the granitoid rocks have typical calcalkaline geochemical features the ree and ocean ridge granite normalized multi element patterns and tectonomagmatic discrimination diagrams as well as biotite geochemistry suggest that the granitoids were formed in a volcanic arc setting the k ar geochronology of the granitoid rocks yielded ages ranging from 85 76 3 17 to 77 49 1 91 ma the field geochemical and geochronological data suggest the following late cretaceous tectonomagmatic scenario for southeast anatolia the ophiolites were formed in a suprasubduction zone tectonic setting whereas the ophiolite related metamorphic rocks formed either during the initiation of intraoceanic subduction or late thrusting 90 ma these units were then overthrust by the malatya keban platform during the progressive elimination of the southern neotethys thrusting of the malatya keban platform over the ophiolites and related metamorphic rocks was followed by the intrusion of the granitoids 88 85 ma along the tauride active continental margin in the southern neotethys

petrology of the tekirova antalya ophiolite southern turkey evidence for diverse magma generations and their tectonic implications during neotethyan subduction the sw antalya complex is an assemblage of mesozoic carbonate platform margin and ophiolitic rocks which record the formation and tectonic emplacement of a small mesozoic ocean basin the late cretaceous ophiolitic rocks are located at two localities namely the relatively intact tekirova ophiolite to the east of kemer zone and the dismembered godene ophiolite to the west of kemer zone the tekirova antalya ophiolite comprises harzburgitic tectonites ultramafic to mafic cumulates isotropic gabbros and sheeted dikes numerous isolated dikes ranging in thickness from 5 cm to 10 m intruded the crustal rocks at different structural levels the isotropic gabbros are represented by gabbro diorite and quartz diorite rocks with granular to ophitic subophitic textures the isolated dikes are characterized by dolerite diabase and microdiorite with ophitic intersertal and microgranular textures these rocks exhibit tholeiitic to alkaline compositions new geochemical data presented in this paper from the isolated dikes and isotropic gabbros suggest that there are three main types of parental basic magmas that form the oceanic crustal rocks of the tekirova antalya ophiolite these are 1 iat series which can be referred to the group i isolated dikes and isotropic gabbros 2 low ti boninitic series characterized by the group ii isolated dike and isotropic gabbros and 3 oib type including the group iii isotropic gabbros the geochemical evidence suggests that the crustal rocks of the tekirova antalya ophiolite were generated from a progressive source depletion from island arc tholeiites iat to boninites therefore a fore arc tectonic setting seems likely for the generation of the crustal rocks from the tekirova antalya ophiolite in the southern branch of neotethys during the late cretaceous the oib type alkaline isotropic gabbros are thought to have resulted from either 1 a late stage magmatic activity fed by melts that originated within an asthenospheric window due to slab break off or 2 subduction of a ridge system which generated oib source across the asthenospheric window that has been no influence of fluids from the subducted slab into the overlying mantle wedge shortly before the emplacement of the tekirova antalya ophiolite onto the tauride platform

a magnetotelluric survey of ophiolites in the neyriz area of southwestern iran a wide band magnetotelluric study of the ophiolitic zone of the zagros orogenic belt was conducted in the neyriz area of southwestern iran the purpose of the study was to image subsurface structures electrically and relocate the main zagros thrust fault in the region the thrust fault has a complex structure with obscure behavior and is believed to be located within a zone of ongoing continental plate convergence the fault zone with a nw se geological trend is parallel to the zagros orogenic belt and separates the neyriz ophiolite assemblage from the adjacent sanandaj sirjan metamorphic zone magnetotelluric data were collected along a sw ne profile across the geologic strike the study included 18 stations and modeling was performed using a 2 d inversion scheme analysis of both modes of magnetotelluric data te and tm clarifies the signatures of large resistivity variation in the study area due to the presence of a high contrast in resistivity between the ophiolites and neighboring rocks we are able to discern two sharp boundaries as faulting planes and borders of the ophiolite radiolarite zone in the north eastern and southwestern parts of the 2 d resistivity models respectively

timing of subduction zone metamorphism during the formation and emplacement of troodos and baer bassit ophiolites insights from 40ar 39ar geochronology the troodos ophiolite in cyprus and baer bassit ophiolite in syria together form part of the tethyan ophiolite belt they were generated in a supra subduction zone setting in late cretaceous times as with many of the ophiolite occurrences in this belt the sequences are closely associated with tectonic coloured melange zones which contain among a variety of lithologies metre to kilometre size blocks of metamorphic rocks precise 40 ar 39 ar laser step heating experiments performed on four amphibolites from sw cyprus and six from nw syria yield plateau ages ranging from 75 7 0 3 ma to 88 9 0 8 ma in cyprus and 71 7 0 5 to 88 4 0 4 ma in syria the older limits of these time spans are coeval with the age of the formation of the associated ophiolites unlike other metamorphic sole rocks which seem to form in relatively short time spans these metamorphic rocks found in cyprus and syria are interpreted to have formed in late cretaceous times by accretion below the overriding troodos and baer bassit crust for a period of 15 18 ma the metamorphic complexes were exhumed by extension and crustal thinning associated with subduction roll back and the rotation of the overriding plate until the cessation of subduction in maastrichtian times in cyprus the exhumed metamorphic complex was incorporated into an accretionary prism constructed primarily of the collapsed mamonia passive margin sequence intercalated with rocks of the troodos ophiolite during plate collision in the maastrichtian concomitantly in syria the baer bassit ophiolite and subcreted metamorphic complex were emplaced onto the arabian passive margin and fragmented into blocks and knockers forming the baer bassit melange

formation of taconic melanges and broken formations in the hamburg klippe central appalachian orogenic belt eastern pennsylvania abstract the hamburg klippe of the central appalachian orogenic belt exposed in eastern pennsylvania displays a complex record of poly phase melange and broken formation development in a convergent margin setting it includes an imbricate stack of tectonic slices which consist of upper cambrian to upper ordovician deep water and continental slope sedimentary rocks emplaced by gravity sliding onto the laurentian passive margin during deposition of the upper ordovician martinsburg formation based on their internal structure and stratigraphy the block matrix ratios and relations and the inferred tectonic settings of origin we have differentiated the following melanges and broken formations whose evolutionary stages coincide with specific deformational phases in a complete orogenic cycle from subduction to collision i sedimentary broken formations without exotic blocks formed by in situ and local down slope remobilization during the early stages of closure of the octoraro sea basin in the early ordovician ii two types of sedimentary melanges with exotic blocks formed at the front of the advancing accretionary wedge during the middle ordovician subduction of the laurentian continental margin beneath a microcontinent magmatic arc tectonic assembly iii layer parallel extensional broken formation and a diapiric melange formed in the outer trench and at the toe of the accretionary wedge respectively during the early late ordovician iv precursory olistostromes formed during the late ordovician collisional episodes as the hamburg klippe was emplaced in the martinsburg formation on the downgoing laurentian continental margin and v contractional deformation related broken formations formed at the base of main thrust faults overprinting the previously formed melanges and broken formations this sequential development of different melange types in the central appalachians was strongly controlled by the degree of consolidation of the layered strata and their rheological differences the structural level of melange formation within the accretionary wedge and the kinematics of deformational processes

record of cenozoic sedimentation from the amanos mountains southern turkey implications for the inception and evolution of the arabia eurasia continental collision abstract the sedimentary succession of the southern amanos mountains bordering the eastern margin of the karasu rift in south central turkey provides a record of environmental change from the eocene lutetian to the upper miocene tortonian that charts the final evolution of the northern margin of the arabian plate prior to and during continental collision eocene shallow marine carbonates hacidagi formation are interpreted as the youngest unit of the arabian passive margin succession deposited on a northwards facing carbonate ramp subsequent deformation and uplift took place during the oligocene represented by folding of the eocene and older strata this is interpreted to be the result of initial continental collision between arabia and eurasia unconformably overlying the eocene limestone are lower miocene conglomerates sandstones and palaeosols up to 150 m thick kici formation these were deposited in a range of marginal marine settings consisting of alluvial fan fan delta facies flood plain as well as basinal facies subsequently during the middle miocene local patch reefs developed in restricted areas kepez formation followed by upper miocene sediments gokdere formation composed of relatively deep water hemipelagic marl with clastic interbeds which represent a transgression during this period the upper miocene becomes sandier upwards this records the regression from the relatively deep water facies to coastal sediments water depth gradually became shallower until during pliocene time the area became continental in nature by the quaternary rifting had resulted in the development of the karasu rift with active alluvial fans along the margins and braided rivers depositing coarse conglomerates in the axial zone these conglomerates are interbedded with basaltic lava flows that resulted from the region extension across the area this research shows that initial continental collision occurred in this area after the lutetian 40 4 ma and before the aquitanian 23 03 ma supporting the hypothesis that the southern neotethys ocean closed during the late eocene to oligocene this was a time of climatic change including the onset of southern hemisphere glaciation in which the closure of the southern neotethys may have had played an important role

geochemical characteristics 40ar 39ar ages and original tectonic setting of the band e zeyarat dar anar ophiolite makran accretionary prism s e iran abstract the makran accretionary prism in southeastern iran contains extensive mesozoic zones of melange and large intact ophiolites representing remnants of the tethys oceanic crust that was subducted beneath eurasia to the north of the makran accretionary prism lies the jaz murian depression which is a subduction related back arc basin the band e zeyarat dar anar ophiolite is one of the ophiolite complexes it is located on the west side of the makran accretionary prism and jaz murian depression and is bounded by two major fault systems the principal rock units of this complex are a gabbro sequence which includes low and high level gabbros an extensive sheeted diabase dike sequence late intrusive rocks which consist largely of trondhjemites and diorites and volcanic rocks which are largely pillow basalts interbedded with pelagic sedimentary rocks including radiolarian chert chondrite and primitive mantle normalized incompatible trace element data and age corrected nd pb and sr isotopic data indicate that the band e zeyarat dar anar ophiolite was derived from a midocean ridge basalt like mantle source the isotopic data also reveal that the source for basalts was indian ocean type mantle based on the rare earth element ree data and small isotopic range all the rocks from the band e zeyarat dar anar ophiolite are cogenetic and were derived by fractionation from melts with a composition similar to average e morb fractionation was controlled by the removal of clinopyroxene hornblende and plagioclase three 40ar 39ar plateau ages of 140 7 2 2 142 9 3 5 and 141 7 1 0 ma and five previously published k ar ages ranging from 121 4 to 146 5 ma for the hornblende gabbros suggest that rocks from this ophiolite were formed during the late jurassic early cretaceous plate reconstructions suggest that the rocks of this complex appear to be approximately contemporaneous with the masirah ophiolite which has crystallization age of 150 ma like masirah the rocks from the band e zeyarat dar anar ophiolite complex represent southern tethyan ocean crust that was formed distinctly earlier than crust preserved in the 90 100 ma bitlis zagros ophiolites including the samail ophiolite

origin of the upper cretaceous tertiary sedimentary basins within the tauride anatolide platform in turkey a number of sedimentary basins formed within the tauride anatolide platform of anatolia during the late cretaceous tertiary period previous studies have proposed different tectonic and evolutionary models for each basin geological characteristics of the basins however suggest that all these basins are of the same origin and that they followed a similar evolutionary model to one another basin development within the tauride anatolide platform took place in a post collisional environment following the northward subduction of the northern neotethys ocean beneath the pontides the closure of the northern neotethys ocean ended with collision of the tauride anatolide platform with the pontide volcanic arc and resulted in large bodies of oceanic remnants thrust over the tauride anatolide platform as ophiolite nappes formation of the sedimentary basins followed the emplacement of the ophiolite nappes as they formed as piggy back basins on top of the underlying thrust ophiolite basement

biostratigraphic zonation and 40ar 39ar ages for the neotethyan khoy ophiolite of nw iran abstract the khoy ophiolite in northwestern iran represents a piece of oceanic lithosphere formed in the mesozoic neotethys this ophiolite consists from bottom to top of well defined basal metamorphic rocks peridotites gabbros and a variety of upper to lower cretaceous deep marine rocks these include pelagic fossiliferous carbonates and basalts as interlayers or exotic blocks four hornblende separates from gabbros and amphibolites give values from 108 to 111 ma the results from microfossil studies show the presence of late cretaceous e g marginotruncana globotruncana and middle to late eocene e g globorotalia orbulonoides planktonic foraminifera the data suggest that although the initial rifting and crystallization of the oceanic crust of the khoy ophiolite began in the late albian the volcanic activities continued through to the late eocene time another possibility for such variation of lithofacies and biofacies and disturbances in the fossil record may be the result of bioturbation and transportation and rapid changes of depositional conditions during eruption of the basaltic lava flows pelagic sediments alone have been listed and of the foraminiferas the first three are planktonic as would be expected only orbulonoides is a benthic form and aberrant the third possibility is that the khoy ophiolite may represent a classic supra subduction type ophiolite where volcanic members of the different parts of oceanic environment e g morb volcanic arc ocean island are now juxtaposed

mesoproterozoic ophiolitic melange from the se periphery of the indian plate u pb zircon ages and tectonic implications abstract the kanigiri melange within the proterozoic nellore khammam schist belt in southern peninsular india includes ophiolitic fragments that represent the remnants of an oceanic plate the ophiolitic units were accreted along a ne trending suture that juxtaposes the proterozoic eastern ghats granulite belt eggb against the archean nellore schist belt of the dharwar craton the ophiolite components in the kanigiri melange include plagiogranites and gabbros which show mutually intrusive relations indicating their coeval nature we report laser ablation icp ms age data and ree geochemistry of zircons from the gabbro and granite the zircons from both gabbro and granite show high ree contents prominent hree enrichment and a conspicuous negative eu anomaly suggesting a common melt source zircon ree abundances and normalized patterns show little intersample and intrasample variations u pb dating of the zircons reveals prominent mesoproterozoic ages for the plagiogranite with the ca 1 33 ga age of the kanigiri ophiolitic melange offering important clues for arc continent collision during the final stages of amalgamation of the columbia derived fragments within the neoproterozoic supercontinent assembly

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

origin and emplacement of the late cretaceous baer bassit ophiolite and its metamorphic sole in nw syria abstract the baer bassit ophiolite of inferred late cretaceous age was emplaced from the south tethys ocean onto the leading edge of the arabian continental margin in latest cretaceous maastrichtian time dismembered sequences in different thrust sheets can be correlated to produce a complete ophiolite sequence with a metamorphic sole at the base overlain in turn by upper mantle tectonite rare cumulates massive and layered gabbros localized high level plagiogranites sheeted dykes basic extrusives and minor fe mn sediments umbers the restored ophiolite sequence is similar to that of the more intact troodos and hatay ophiolites but dissimilar to oman the baer bassit extrusives are magnesian and strongly depleted comparable to primitive island arc tholeiites and some boninitic lavas which favours a subduction related origin a well developed metamorphic sole is divisible into high grade amphibolite facies assemblages in the north and lower grade greenschist facies assemblages in the centre of the region but no complete inverted metamorphic gradient is preserved in any one local area the protoliths of both the high grade amphibolites and lower grade rocks greenschists are interpreted as alkali basalts and pelagic sediments including chert similar to the volcanic rocks in an underlying unmetamorphosed melange the metamorphic fabrics progressively evolved from ductile to brittle during tectonic transport towards the southeast most of the metamorphic fabrics evolved during intense shearing but some of the alkaline metabasites apparently were metamorphosed under relatively static strain conditions the apparent absence of preserved inverted metamorphic gradients in baer bassit may reflect a complex deformation history during emplacement alternatively differing p t conditions may be recorded at different depths at the base of the over riding mantle wedge during emplacement the front of the ophiolite was tectonically imbricated and overthrust by the main ultramafic slab bassit massif the thickest massif baer is underlain by a high grade metamorphic sole and was internally shortened but without thrust duplication of the entire ophiolite sequence following covering by late maastrichtian palaeogene marine calcareous sediments the area was subjected to mid tertiary regional folding this was followed by neogene dominantly left lateral strike slip deformation along the african eurasian plate boundary extending from south of cyprus to the dead sea transform fault as a result the originally emplaced thrust sheets were dissected into three main composite units baer bassit and the southeastern units separated by strongly faulted and sheared ophiolitic blocks and unmetamorphosed volcanic sedimentary melange

the ophiolite related mersin melange southern turkey its role in the tectonic sedimentary setting of tethys in the eastern mediterranean region the mersin melange underlies the intact mersin ophiolite and its metamorphic sole to the south of the mesozoic tauride carbonate platform in southern turkey the melange varies from chaotic melange to broken formation in which some stratigraphic continuity can be recognized based on study of the broken formation four lithological associations are recognized 1 shallow water platform association dominated by upper palaeozoic lower cretaceous neritic carbonates 2 rift related volcanogenic terrigenous pelagic association mainly upper triassic andesitic acidic volcanogenic rocks siliciclastic gravity flows basinal carbonates and radiolarites 3 within plate type basalt radiolarite pelagic limestone association interpreted as upper jurassic lower cretaceous seamounts with associated radiolarian sediments and upper cretaceous pelagic carbonates 4 ophiolite derived association including fragments of the upper cretaceous mersin ophiolite and its metamorphic sole locally the ophiolitic melange includes granite that yielded a k ar radiometric age of 375 7 10 5 ma late devonian this granite appears to be subduction influenced based on immobile element composition the mersin melange documents the following history 1 triassic rifting of the tauride continent 2 jurassic cretaceous passive margin subsidence 3 oceanic seamount genesis 4 cretaceous supra subduction zone ophiolite genesis 5 late cretaceous intra oceanic convergence metamorphic sole formation and 6 latest cretaceous emplacement onto the tauride microcontinent and related backthrusting regional comparisons show that the restored mersin melange is similar to the beysehir hoyran nappes further northwest and a northerly origin best fits the regional geological picture these remnants of a north neotethys inner tauride ocean were formed and emplaced to the north of the tauride carbonate platform they are dissimilar to melanges and related units in northern syria western cyprus and southwestern turkey which are interpreted as remnants of a south neotethys early high temperature ductile transport lineations within amphibolites of the metamorphic sole of the mersin ophiolite are generally orientated e w possibly resulting from vertical axis rotation of the ophiolite while still in an oceanic setting by contrast the commonly northward facing later stage brittle structures are explained by backthrusting of the ophiolite and melange related to exhumation of the partially subducted northern leading edge of the tauride continent

characteristics of ophiolite related metamorphic rocks in the beysehir ophiolitic melange central taurides turkey deduced from whole rock and mineral chemistry small outcrops of the metamorphic rocks of the beysehir ophiolite appear to the west of gencek and to the south of durak south of beysehir lake in the central tauride belt in turkey amphibolitic rocks in the ophiolitic melange have an igneous origin protoliths of these rocks were probably alkali basalts gabbros or some ultramafic cumulates such as pyroxenite the amphibolites of the beysehir ophiolite can be divided into four groups 1 amphibolecgarnetcplagioclasegepidote as secondary minerals gopaque such as ilmeniteg accessory minerals such as sphene and apatite 2 amphibolecpyroxenecplagioclasegepidotegaccessory minerals such as sphene apatitegchlorite calcite as secondary mineral 3 amphibolegplagioclasegopaquegaccessory minerals 4 amphibolec plagioclasegepidotegbiotite and muscovitegopaquegaccessory minerals these metamorphic rocks show mainly granoblastic grano nematoblastic porphyroblastic and or poikiloblastic textures all amphiboles in the amphibolites are calcic and cluster in the range from magnesio hastingsite pargasite to actinolite amphibole compositions are characterized by sio2z 38 02 54 3 al2o3z 1 5 12 8 feoz 10 03 14 67 k2oz 0 2 1 8 mgoz 5 5 15 7 mg z 0 3 0 8 the amphibolites show an alkaline to subalkaline character however the primitive mantle normalized incompatible trace element diagram shows close similarity with the typical ocean island basalt oib pattern the rock chondrite normalized ree diagram of the amphibolites also confirms their oib signature tectonomagmatic discrimination diagrams based on the immobile trace elements suggest a mostly within plate alkali basalt wpb environment beysehir ophiolitic melange contains amphibolites from ophiolite related metamorphic rocks but the matrix of the beysehir ophiolitic melange is not metamorphosed blocks of metamorphic rocks and the ophiolitic rocks may have been incorporated into the ophiolitic melange in an oceanic environment during the late cretaceous by tectonic forces q 2005 elsevier ltd all rights reserved

reassessing the age of karpathos ophiolite dodecanese greece consequences for aegean correlations and neotethys evolution while the neogene history of the eastern mediterranean region is now fairly well understood our knowledge of older regional palaeogeographies is less accurate especially the positions of blocks and nappes constituting the aegean islands prior to the cenozoic our study focuses on the ophiolite exposed on the island of karpathos dodecanese which is located in the aegean fore arc at a pivotal position between the western and eastern ophiolites of the mediterranean region and where conflicting late jurassic and late cretaceous ages have led to diverging tectonic and palaeogeographic interpretations to test these ages we targeted the radiolarian cherts that depositionally overlie the ophiolite and extracted diagnostic radiolarian assemblages of aptian 125 113 ma early middle albian 113 105 ma and turonian 93 9 89 8 ma ages these results suggest that previous late cretaceous k ar isotopic ages from 95 3 4 2 ma to 81 2 1 6 ma may have been reset by late cretaceous metamorphism or affected by argon loss overall the new early cretaceous ages show that the karpathos ophiolite should not be correlated with the pindos nappes of greece or the ophiolites of cyprus or syria but rather with the lycian nappes of turkey and their root located in the izmir ankara erzincan suture zone therefore the karpathos ophiolite represents a remnant of the northern neotethys not the pindos ocean or the proto eastern mediterranean basin

the role of the early tertiary ulukisla basin southern turkey in suturing of the mesozoic tethys ocean the maastrichtian late eocene ulukisla basin is representative of the tectonic and sedimentary evolution of prominent early tertiary basins in central anatolia including the tuzgolu and arkisla basins the ulukisla basin overlies an ophiolitic melange of late cretaceous age between the bolkar carbonate platform to the south and the nigde kirsehir metamorphic massif to the north the basin stratigraphy records successive phases of transgression subsidence volcanism evaporite deposition deformation and uplift subsidence curves are consistent with an extensional or transtensional basin origin terminated by uplift the ulukisla basin includes a thick succession c 2 km of upper paleocene lower eocene basaltic to andesitic submarine pillow lavas lava flows volcaniclastic rocks and intercalated limestones whole rock xrf chemical analysis indicates a within plate origin with a marked subduction influence believed to be inherited rather than contemporaneous the ulukisla basin formed after late cretaceous ophiolite and melange emplacement and ended with late eocene emergence deformation and onset of oligo miocene non marine deposition we propose that late cretaceous ophiolite and melange emplacement reflect initial ocean basin closure this was followed by a long period c 30 ma of microcontinental adjustment including possible strike slip palaeorotation and suture tightening during which the early tertiary ulukisla basin developed possible driving forces were regional slab pull of a relict subduction zone or oblique diachronous convergence suture tightening was complete by late eocene time marked by collisional deformation and regional uplift

tectonomagmatic evolution of bimodal plutons in the central anatolian crystalline complex turkey abstract the nw trending agacoren intrusive suite ais on the east side of the salt lake tuz golu turkey is part of a curvilinear volcanoplutonic complex along the western edge of the central anatolian crystalline complex cacc granitoids constitute the predominant lithological group within the ais and range in composition from monzonite through granite to alkali feldspar granite gabbroic rocks occur as irregular intrusive bodies with sinusoidal irregular contacts with the granitoid plutons and vary from dioritic compositions at the contacts to cumulate amphibole gabbros in their center these gabbroid to granitoid rocks are all subalkaline and display tholeiitic to calcalkaline affinities respectively modeling of the major element and trace element chemistry of the granitoids to gabbroids together with their field relations suggest that these rocks formed synchronously from a melt source that involved both mantle and crustal components mafic magmas were likely derived from a metasomatized u

biochronology of jurassic and early cretaceous radiolarites from the lycian melange sw turkey and implications for the evolution of the northern neotethyan ocean new radiolarian ages for blocks of radiolarian cherts associated with other blocks of distal pelagic facies and ophiolitic lithologies within the lycian melange sw turkey indicate deposition during mid jurassic to early cretaceous time radiolarites overlying pink pelagic limestones of an allochthonous carbonate unit accumulated during the midto late jurassic on the basis of structural evidence the lycian melange is inferred to have been rooted within the northern neotethys to the north of the tauride anatolide microcontinent the lycian radiolarites can be compared with other dated radiolarites from the izmir ankara suture the root zone of the northern neotethyan ocean based on all the available radiolarian data it is inferred that radiolarites accumulated within the northern neotethys in western turkey from late triassic mid carnian to late norian to midcretaceous cenomanian time the radiolarites were later detached from their inferred oceanic basement and accreted within a subduction complex during the late cretaceous turonian maastrichtian and emplaced over the northern margin of the tauride anatolide continent together with slices of continental margin and ophiolitic lithologies following the development of mesozoic radiolarian biostratigraphical schemes during the last 25 years radiolarian biochronology has become invaluable for reconstructing the palaeogeography palaeoceanography and tectonic evolution of tethyan oceanic basins and margins de wever 1989 robertson et al 1991 de wever et al 1994 danelian robertson 1997 2001 radiolarites in the tethyan realm commonly occur within melanges that are interpreted as parts of accretionary prisms related to subduction of ocean crust robertson 2002 2004 radiolarian ages from such melanges provide valuable age constraints on related geological processes including spreading intra plate volcanism and tectonic accretion e g al riyami et al 2001 beccaletto et al 2005 here we will present the first radiolarian evidence from the lycian melange an east west trending late mesozoic accretionary complex in sw turkey collins robertson 1997 fig 1 this melange forms part of the wellknown lycian nappes in sw turkey de graciancky 1972 poisson 1977 1984 collins robertson 1998 the root zone of the melange is considered to lie to the north of the regional basement represented by the tauride anatolide platform collins robertson 1998 2003 and is inferred to lie within the izmir ankara suture zone to the north of the menderes massif robertson pickett 2000 robertson et al 2004 we will also review the limited available data for radiolarites from comparable tectonic units within the izmir ankara suture zone and the bey daglari we conclude by considering the implications of the available radiolarian evidence for the evolution of the mesozoic tethyan ocean

initial subduction of neo tethyan ocean geochemical records in chromite and mineral inclusions in the pozanti karsanti ophiolite southern turkey abstract chromitites in the pozanti karsanti ophiolite in turkey mainly occur as podiform chromitites within mantle harzburgite and stratiform like chromitites in mantle crust transition zone chromites in chromitites have varing cr from 62 8 to 80 3 and can be divided into two types namely intermediate cr 62 8 69 2 and high cr cr 73 9 80 3 types major elements of the high cr chromitite have an affinity with boninite whereas the intermediate chromitite shows transitional features between morb and boninite the compositional differences in clinopyroxene inclusions between intermediate and high cr chromitite coupled with the relatively high trace element contents e g v ga in the high cr chromitite indicate distinctive parental magmas trace elemental profile analysis of a nodular chromite grain in one nodular chromitite sample pk14 41 demonstrates significant but non systematic variations from the core to the rim which also confirmed the compositional heterogeneity of the parental magmas the presence of primary hydrous mineral inclusions such as amphibole in chromite together with ca rich minerals e g calcite reflect the water rich and ca rich characteristics of the parental magma the higher fo2 of high cr chromitite evidenced by the lower v mn values may be due to more oxidized fluids released from downgoing crustal materials thus we conclude that the parental magmas of the pozanti karsanti chromitite were derived from a proto forearc mantle and evolved to higher fo2 with the subduction initiation at that time but were water and ca rich in general

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

hot and deep rock record of subduction initiation and exhumation of high temperature high pressure metamorphic rocks feather river ultramafic belt california abstract studies of a 10 to 300 m thick unit of high grade metamorphic rock external schists that crops out along the western border of the feather river ultramafic belt frb northern california yield new insights into subduction initiation and ophiolite emplacement processes the high temperature t foliation of the external schists dip moderately to steeply eastward beneath the ultramafic rocks of the frb a 150 km long slab of suboceanic upper mantle and the high t fabric shows a tops to the west frb side up sense of shear the structurally highest external schists record peak metamorphic conditions of 650 760 c at 1 3 2 2 gpa in contrast sheeted dikes of the devil s gate ophiolite that overlie the ultramafic rocks yield metamorphic conditions of 710 730 c at about 0 3 0 7 gpa a km scale lens of amphibolite within ultramafic rocks yields somewhat lower pressures than the structurally highest external schist as do the structurally lower rocks within the external schists significant exhumation of the external schists relative to the structurally overlying ophiolitic rocks occurred along at least two major zones and the most significant exhumation was accommodated at least 1 5 km structurally above the ultramafic external schist contact based on available geochronology intraoceanic subduction may have initiated at approximately 240 ma and exposure of the external schist occurred prior to the deposition of rocks in the structurally highest part of the calaveras complex minimum 177 ma a subduction complex that structurally underlies the external schists high t metamorphism of the devil s gate ophiolite may have resulted from partial failed ridge subduction

evidence of eocene high temperature high pressure metamorphism of ophiolitic rocks and granitoid intrusion related to neotethyan subduction processes dogansehir area se anatolia

shear strength characteristics of a residual soil shallow landslides in natural residual soils slopes are common all over the world the slip surfaces associated with these landslides are often situated above the groundwater table therefore it i

neotethyan ophiolitic rocks of the anatolides of nw turkey and comparison with tauride ophiolites the i2zmir ankara erzincan zone in turkey is part of the anatolide belt in nw anatolia near kutahya the ophiolitic rocks within the i2zmir ankara erzincan suture zone have a tholeiitic character and oceanic back arc chemistry amphibolites form a metamorphic sole to part of the ophiolite in the kutahya region and yield an 40 ar 39 ar age of 93 2 ma interpreted to record high grade metamorphism and intra oceanic thrusting of pre existing ocean crust gabbros and dykes yield 40 ar 39 ar ages of 94 13 ma and 48 12 ma the first is suggested to be the ophiolite formation age and the second a regional metamorphic event the ophiolitic rocks of the kutahya region are composite and record several events in the evolution of a neotethyan seaway situated in north central anatolia and farther east they are interpreted to have formed in a small ocean basin marginal to the subducting i2zmir ankara erzincan ocean the kutahya ophiolites of the anatolide belt are similar in age to the tauride ophiolites and the sub ophiolite metamorphic rocks and dykes in the ultramafic parts of the ophiolites in the anatolide tauride block formed at the same intraoceanic subduction zone within the same neotethyan ocean

the cretan ophiolite bearing melange greece a remnant of alpine accretionary wedge abstract new data collected in central crete on the ophiolite bearing units result in a better understanding of the role and tectonic significance of these units in the construction of this segment of the hellenides these nappes are composed of three main tectonic units that characterized by different metamorphic facies conditions are represented by an un metamorphosed lower unit a greenschist to hp greenschist facies intermediate unit and a blueschist facies upper unit these chaotic thrust nappes include blocks of oceanic and continental deriving rocks and can be considered as a remnant of an accretionary complex the lower unit represents the toe of the wedge whereas the intermediate and upper units refer to the innermost and deeper subducted portions exhumed and superimposed on top of each other during the early stages of continental collision the structural evolution of the accretionary wedge was controlled by four main contractional deformation events that including distinct groups of structures developed at different crustal levels were driven by sse and ssw directions of tectonic transport our data strongly suggest that the ophiolite bearing tectonic wedge was accreted during the paleogene subduction of a late jurassic cretaceous oceanic realm beneath the continental margin of the pelagonian domain and it was successively involved in the continental collision with the adria block the greenschist to blueschist facies metamorphism and the subsequent exhumation and emplacement of the intermediate and upper units above the frontal portion of the wedge may mainly be due to deep duplexing marking the onset of continental collision we thus suggest that the ophiolite bearing units of crete represent a single suture zone related to the closure of a unique oceanic domain pindos cycladic ocean subducted beneath the internal hellenides platform continental domains thus assuming the significance of a southern oceanic seaway of the largest eastern neotethys developed since the triassic between eurasia and africa

neotethys closure history of anatolia insights from 40ar 39ar geochronology and p t estimation in high pressure metasedimentary rocks the multiple high pressure hp low temperature lt metamorphic units of western and central anatolia offer a great opportunity to investigate the subduction and continental accretion related evolution of the eastern limb of the long lived aegean subduction system recent reports of the hp lt index mineral fe mg carpholite in three metasedimentary units of the gondwana derived anatolide tauride continental block namely the afyon zone the oren unit and the southern menderes massif suggest a more complicated scenario than the single continental accretion model generally put forward in previous studies this study presents the first isotopic dates white mica 40ar 39ar geochronology and where possible are combined with p t estimates chlorite thermometry phengite barometry multi equilibrium thermobarometry on carpholite bearing rocks from these three hp lt metasedimentary units it is shown that in the afyon zone carpholite bearing assemblages were retrogressed through greenschist facies conditions at c 67 62 ma early retrograde stages in the oren unit are dated to 63 59 ma in the kurudere nebiler unit hp mesozoic cover of the southern menderes massif hp retrograde stages are dated to c 45 ma and post collisional cooling to c 26 ma these new results support that the oren unit represents the westernmost continuation of the afyon zone whereas the kurudere nebiler unit correlates with the cycladic blueschist unit of the aegean domain in western anatolia three successive hp lt metamorphic belts thus formed the northernmost tavsanli zone c 88 82 ma the oren afyon zone between 70 and 65 ma and the kurudere nebiler unit c 52 45 ma the southward younging trend of the hp lt metamorphism from the upper and internal to the deeper and more external structural units as in the aegean domain points to the persistence of subduction in western anatolia between 93 90 and c 35 ma after the accretion of the menderes tauride terrane in eocene times subduction stopped leading to continental collision and associated barrovian type metamorphism because by contrast the aegean subduction did remain active due to slab roll back and trench migration the eastern limb below southwestern anatolia of the hellenic slab was dramatically curved and consequently teared it therefore is suggested that the possibility for subduction to continue after the accretion of buoyant e g continental terranes probably depends much on palaeogeography

structure and kinematics of the central sivas basin turkey salt deposition and tectonics in an evolving fold and thrust belt this work has been made possible by funding from total s a in the framework of the structural geology chair at e2s university of pau pays adour held by jean paul callot

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

development of concepts concerning the genesis and emplacement of tethyan ophiolites in the eastern mediterranean and oman regions this article uses evidence mainly from the eastern mediterranean and oman to help understand the origin and emplacement of ophiolites field studies in these regions emphasize the diversity of ophiolite related sedimentary and tectonic processes topics to be discussed here include the sedimentary covers of ophiolites their metamorphic soles related melanges and emplaced continental margin slope rise units modes of ophiolite emplacement will also be considered and tectonic reconstructions that have a direct bearing on the origin and emplacement of ophiolites the writer argues that there is compelling evidence that many ophiolites formed by spreading above intraoceanic subduction zones evidence from their intact sedimentary covers however indicates that such subduction was only incipient in most cases as directly associated volcanic arcs or back arc basins are rare metamorphic soles record fragments of oceanic lithosphere derived from settings ranging from open ocean to continental slope rise settings underlying melanges record the subduction of most of the ocean lithosphere formed at spreading ridges continental margin units beneath ophiolites demonstrate that these ophiolites were formed in ocean basins that were mainly initiated by continental rifting in the eastern mediterranean and oman regions ophiolite emplacement was commonly achieved by trench margin collision although strike slip transpression and large scale accretion along subducting margins played a role in some cases taking account of the mesozoic palaeotectonic setting of the eastern mediterranean region it is widely believed that ophiolites of two main ages mid jurassic and late cretaceous were formed in several small oceanic basins separated by rifted microcontinents the history of tethys in pre mesozoic time remains more open to question lastly giant subduction related ophiolites as in oman cyprus or the balkans may not be forming anywhere in the world ocean today but may instead relate to rare events in earth history when regional to global plate boundaries were drastically reorganised

overview of ophiolites and related units in the late palaeozoic early cenozoic magmatic and tectonic development of tethys in the northern part of the balkan region abstract the northern balkan peninsula including serbia montenegro bosnia croatia and the former yugoslavian republic of macedonia represents an excellent region for the study of tectonic processes related to mesozoic tethyan ophiolite genesis and emplacement we first summarise the main tectonic units of the northern balkan peninsula and then use this information to discuss tectonic processes including rifting sea floor spreading ophiolite genesis and emplacement melange accretion ocean basin closure and collision we then discuss alternative models of ophiolite genesis and emplacement for the region and suggest that multi ocean basin interpretations fit the data better than single ocean basin interpretations rifting of adria gondwana during the triassic created a rift in the south budva zone and opened a triassic oceanic basin further north dinaride ocean occurrences of inferred sub continental mantle lithosphere in the dinaride ophiolite belt e g zlatibor may record extensional exhumation within an ocean continent transition zone bordering the adria dinaride continent this was followed by emplacement together with ophiolites and melange during upper jurassic early cretaceous time upper triassic radiolarites and mid ocean ridge type basalts formed at a spreading ridge after continental break up the oceanic lithosphere of the dinaride ophiolite belt was partly generated above a subduction zone the metamorphic soles of the dinaride ophiolites formed during mid late jurassic mainly based on k ar dating widespread melange that is associated with the ophiolites represents a subduction complex controlled by tectonic accretion and sedimentary reworking in trench and fore arc basin settings a possible cause of jurassic dinaride ophiolite emplacement was collision of a subduction trench with a continental margin further north mesozoic oceanic lithosphere subducted northeastwards present coordinates opening a late jurassic marginal basin in the main vardar zone the dinaride ocean in the south closed during late jurassic early cretaceous time tithonian berriasian deformed oceanic crust melange and magmatic arc rocks further north main vardar zone were transgressed by mainly clastic sediments during the early cretaceous however part of the vardar ocean vardar zone western belt or sava zone remained partially open until latest cretaceous time generally northward subduction within this remnant ocean triggered further supra subduction zone ophiolite genesis during the late cretaceous the ocean closed by the maastrichtian followed by early cenozoic regional scale southward thrusting that locally intercalated older and younger mesozoic ophiolites and melanges future progress particularly depends on determining the crystallisation ages of the ophiolites obtaining better structural data on the direction of initial ophiolite emplacement and unravelling the palaeozoic tectonic development of the eurasian continental margin

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

rotational deformation in the jurassic mesohellenic ophiolites greece and its tectonic significance abstract the jurassic pindos and vourinos ophiolites in the western hellenides of greece are part of the mesohellenic mafic ultramafic slab underlying the eocene miocene sedimentary basin mesohellenic trough the tectonic incorporation of this oceanic slab into the western edge of the pelagonian subcontinent occurred via trench passive margin collision in the late jurassic much of the tectonic architecture of these ophiolites particularly vourinos was acquired during progressive inhomogeneous deformation associated with the initial displacement of the jurassic oceanic crust from its original igneous environment of formation and its subsequent tectonic emplacement eastward onto the pelagonian margin the heterogeneous deformation in the mantle and crustal sequences of the pindos vourinos ophiolites occurred in ductile ductile brittle and brittle fields synchronously as the jurassic oceanic lithosphere was translated eastward it also resulted in differential horizontal rotations within the displaced oceanic slab areas retaining high temperature diapiric mantle fabric appear to have been passively translated by lower temperature ductile shearing commonly along mylonite zones individual dunite bodies in the harzburgite tectonites indicate movement distances of at least kilometer scale pervasively mylonitic domains within the upper mantle peridotites suggest elongation on the order of five to ten times in the direction of ophiolite emplacement seafloor spreading related high temperature mantle structures within the pindos and vourinos ophiolites are sub parallel imprinted ductile kinematic indicators and ductile shear zones pervasive to the mantle and lower crustal sections in both ophiolites are also sub parallel consistent with the direction of tectonic vergence and appear traceable across the sedimentary overburden of the mesohellenic trough these geometric relations imply that the pindos vourinos ophiolites retain their relative orientations from the time of cessation of ductile deformation within the ophiolitic slab more than 90 anticlockwise horizontal rotation of the vourinos ophiolite seems to have taken place during progressive simple shear deformation associated with the eastward emplacement of the jurassic oceanic lithosphere this kind of rotational deformation postdating the igneous accretion of ancient oceanic crust may be common in many ophiolites and should be carefully distinguished from tectonic extension related vertical rotational deformation developed during their seafloor spreading evolution

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

metamorphic sole rocks and their mafic dykes in the eastern tauride belt ophiolites southern turkey implications for oib type magma generation following slab break off the metamorphic sole rocks observed between the pozanti karsanti ophiolite and the melange unit are located on the eastern part of the tauride carbonate platform they consist of ortho amphibolites at the top and metasedimentary lithologies at the base amphibolites from the metamorphic sole rocks are represented by oib morb and iat based on their major trace and ree compositions the isolated dolerite dykes intrude both the metamorphic sole rocks and the ophiolitic unit at different structural levels the dolerite dykes cutting the metamorphic sole rocks are enriched in lile and depleted in hfse enrichment in lile such as th relative to hfse is indicative of the presence of a subduction component flat lying ree patterns of the dolerite dykes also confirm an iat source pyroxenite and albitite dykes also cut the metamorphic sole rocks ree patterns of pyroxenite dykes show prominent lree enrichment similar to that observed in within plate alkaline basalts the alkaline isolated pyroxenite dykes were probably the result of late stage magmatism fed by melts that originated from an oib source shortly before the emplacement of the pozanti karsanti ophiolite onto the tauride carbonate platform a hydrothermal alteration stage is characterized by albitite formation in the joints of the metamorphic sole rocks and by secondary mineralization along the contact zones of dolerite dykes mineral parageneses in the metamorphic sole rocks exhibit amphibolite and greenschist facies assemblages geothermobarometric studies based on a newly recognized mineral assemblage e g kyanite and chemical compositions of minerals in the metamorphic sole rocks indicate that the metamorphic temperature during the metamorphism was 570 580 c and the pressure was around 5 6 kbar

first balanced cross section across the taurides fold thrust belt geological constraints on the subduction history of the antalya slab in southern anatolia eastern mediterranean subduction accommodated africa eurasia convergence since mesozoic time and produced multiple subducted slab fragments in the mantle below anatolia these included the north dipping cyprus and ene dipping antalya slabs which are currently separated by an upper mantle slab gap segmentation of these slabs and associated mantle flow may have contributed to 400 km of post to middle eocene plate convergence was accommodated between the taurides and its beydaglari platform foreland and instead must have been accommodated south of beydaglari the associated southward plate boundary jump separated the antalya slab from the african plate and the cyprus slab the isolated antalya slab was left in an intraplate setting and is probably still attached to beydaglari today we suggest the continental composition of the antalya slab may have prevented its detachment finally the gap between the antalya and cyprus slabs existed since at least eocene time their decoupling likely did not contribute to late neogene central anatolian plateau uplift

late cretaceous infant intra oceanic arc volcanism the central pontides turkey petrogenetic and tectonic implications abstract a tectonic slice of an arc sequence consisting of low grade metavolcanic rocks and overlying metasedimentary succession is exposed in the central pontides north of the izmir ankara erzincan suture separating laurasia from gondwana derived terranes the metavolcanic rocks mainly consist of basaltic andesite andesite and mafic cognate xenolith bearing rhyolite with their pyroclastic equivalents which are interbedded with recrystallized pelagic limestone and chert the metasedimentary succession comprises recrystallized micritic limestone with rare volcanogenic metaclastic rocks and stratigraphically overlies the metavolcanic rocks the geochemistry of the metavolcanic rocks indicates an arc setting evidenced by depletion of hfse ti p and nb and enrichment of fluid mobile lile identical trace and rare earth elements compositions of basaltic andesites andesites and rhyolites suggest that they are cogenetic and derived from a common parental magma the arc sequence crops out between an albian turonian subduction accretionary complex representing the laurasian active margin and an ophiolitic melange absence of continent derived detritus in the arc sequence and its tectonic setting in a wide cretaceous accretionary complex suggest that the kosdag arc was intra oceanic zircons from two metarhyolite samples give late cretaceous 93 8 1 9 and 94 4 1 9 ma u pb ages these ages are the same as the age of the supra subduction ophiolites in western turkey which implies that that the kosdag arc may represent part of the incipient arc formed during the generation of the supra subduction ophiolites the low grade regional metamorphism in the kosdag arc is constrained to 69 9 0 4 ma by 40 ar 39 ar muscovite dating indicating that the arc sequence became part of a wide tethyan cretaceous accretionary complex by the latest cretaceous non collisional cessation of the arc volcanism is possibly associated with southward migration of the magmatism as in the izu bonin mariana arc system

coexistence of compositionally heterogeneous chromitites in the antalya isparta ophiolitic suite sw turkey a record of sequential magmatic processes in the sub arc lithospheric mantle abstract the antalya isparta region in southwestern turkey is well known for its large ophiolitic peridotite exposures which host various chromite orebodies these are small sized massive to disseminated in texture chromitites occurring in the form of lenses or veinlets and commonly surrounded by dunite envelopes of variable thickness chromitite seams from the antalya mantle suite are both high and intermediate cr varieties cr 0 56 0 83 whereas chromitites in the isparta mantle sequence are exclusively cr rich cr 0 75 0 85 in situ minor and trace element abundances obtained by la icp ms analyses of unaltered cr spinel from the cr rich chromitites are comparable to those reported in cr spinel of chromitites from typical fore arc peridotite complexes however minor and trace element concentrations in cr spinel from intermediate chromitites are dissimilar to those acquired from cr spinels of chromitites from well known back arc basin derived ultramafic massifs calculation of parental magma compositions indicates that both types of chromitites share a common parentage with progressively fractionating arc related melts the studied chromitites are characterized by a systematic enrichment in ipge os ir and ru 41 317 ppb with respect to ppge rh pt and pd 3 49 ppb resulting in negatively sloping chondrite normalized pge patterns that are less fractionated in intermediate chromitites their noble mineral assemblage is vastly dominated by tiny 10 m euhedral laurite crystals followed by subsidiary irarsite and trivial amounts of os ir alloy grains pgm grains are not encountered in the intermediate chromitites potentially due to crystallization resulting from pge poor melt laurite is os poor and exhibits a narrow range of os for ru substitution ru ru os 0 75 0 99 however the concomitance of laurite and millerite in the cr rich chromitites of the mutual antalya isparta mantle suite is in favour of their precipitation from an os depleted melt characterized by local and rapid variations of fs2 prior to or coevally with cr spinel crystallization moreover the presence of amphibole inclusions in cr spinel indicates that the melt triggered chromitite genesis potentially involved a hydrous component overall data suggest that investigated orebodies were produced by a successively fractionating arc derived melt that generated compositionally distinct chromitites at two different pseudo stratigraphic levels within the antalya isparta arc type mantle suite

curie point depth map of turkey summary a curie point isotherm map of the whole of turkey has been prepared from aeromagnetic data by means of a spectral analysis technique the most characteristic signature of this map is that the shallow depths generally correlated with the young volcanic rocks and the thinned crustal thicknesses in the west reveal geothermal fields and several hot springs the orogenic pontide belt of the black sea region in the north the western taurus belt in the south and some high plateaus in eastern turkey show that the deepest curie isotherm depths range between 20 and 29 km depth contour lines elongating in an almost e w direction are due to the overlapping percentage of adjacent data blocks of 50 per cent in the e w direction and to magnetic anomalies trending in the e w direction curie isotherm depths are in the range 6 to 10 km in the aegean region and are characterized by e w and ne sw trending graben structures as expected since the region has crustal thinning and many hot springs and geothermal fields these imply the existence of shallow heat sources that could be utilized for electricity heating of towns and cities greenhouse and health purposes

structural anatomy of the ligurian accretionary wedge monferrato nw italy and evolution of superposed melanges we document in this study the internal structure of the late cretaceous late oligocene ligurian accretionary wedge in northwestern italy and the occurrence in this exhumed wedge of broken formation and three different types of melanges that formed sequentially through time the broken formation is the oldest unit in the accretionary wedge and shows bedding parallel boudinage structures which developed as a result of layer parallel extension at the toe of the internal part of the alpine wedge front during the late cretaceous middle eocene this broken formation experienced an overprint of tectonic diapiric and sedimentary processes as a result of continental collision in the late oligocene the ne vergent thrusting and associated shortening produced a structurally ordered block in matrix fabric through mixing of both native and exotic blocks forming the tectonic melange the concentration of overpressurized fluids along the thrust fault planes triggered the upward rise of shaly material producing the diapiric melange which in turn provided the source material for the downslope emplacement of the youngest late oligocene sedimentary melange the sedimentary melange units unconformably cover the collisional thrust faults constraining the timing of both this episode of contractional deformation related to continental collision and the combination and overlap of tectonic diapiric and sedimentary processes our multiscale structural analysis of the ligurian accretionary wedge shows that tectonic diapiric and sedimentary processes played a significant role in its evolution and that the interplay between and the superposition of these different processes strongly controlled the dynamic equilibrium of the accretionary wedge in the nw apennines western alps this kind of polygenetic melange development may be common in many modern and ancient accretionary complexes and the processes involved in their formation are likely to be responsible for major tsunamic events in convergent margins

tethyan ophiolites and tethyan seaways tethyan ophiolites have played a major role in the development of the ophiolite concept during the past 200 years and contributed significantly to the formulations of the suprasubduction zone ssz ophiolite paradigm and the plate tectonics theory their melt evolution and magmatic construction witnessed the dispersal of the supercontinent pangaea via continental rifting and seafloor spreading opening and closure of multiple seaways in an eastward widening latitudinal ocean basin neotethys and deep mantle recycling processes through subduction zone tectonics and plume activities neotethyan ophiolites are highly diverse in their crustal mantle structures and compositions pointing to major differences in their melt sources and tectonic settings of magmatic construction the papers in this thematic set demonstrate these differences in the neotethyan ophiolite record through new structural geochemical isotopic and geochronological data and interpretations the jurassic western alpine ophiolites formed in a narrow basin alpine tethys that developed between europe and north africa adria iberia their peridotites represent exhumed continental lithospheric mantle the triassic jurassic and cretaceous ophiolites east of adria formed in different neotethyan seaways and their ssz magmatic construction involved multiple episodes of melting depletion and refertilization of subduction modified oceanic mantle the late cretaceous peri arabian and peri indian ophiolites which are discontinuously exposed along a c 9000 km long belt from sw anatolia to se tibet formed above a trans tethyan subduction accretion system within southern neotethys diachronous collisions of arabia and india with this intraoceanic subduction accretion system in the latest mesozoic and the paleogene respectively resulted in diachronous ophiolite emplacement in the mediterranean and tibetan himalayan orogenic belts thematic collection this article is part of the tethyan ophiolites and tethyan seaways collection available at https www lyellcollection org cc tethyan ophiolites and tethyan seaways

geochemical and petrological aspects of dike intrusions in the lycian ophiolites sw turkey a case study for the dike emplacement along the tauride belt ophiolites lycian ophiolites located in the western taurides are cut at all structural levels by dolerite and gabbro dikes the dolerite dikes from this area are both pristine and metamorphosed the non metamorphosed dikes are observed both in the peridotites and in the metamorphic sole rocks accordingly the non metamorphosed dikes cutting the metamorphic sole were generated after cooling of the metamorphic sole rocks the metamorphosed dolerite dikes are only observed in the peridotites the physical conditions and timing of the metamorphism for the metamorphosed dolerite dikes are similar to those of the metamorphic sole rocks of the lycian ophiolites suggesting that the metamorphosed dolerite dikes were metamorphosed together with the metamorphic sole rocks therefore the dike injections in the western part of the tauride belt ophiolites occurred before and after the generation of the metamorphic sole rocks all metamorphosed and non metamorphosed dikes are considered to have the same origin and all of them are subduction related as inferred from whole rock geochemistry and lead isotopes lead isotope compositions of whole rocks of both dike groups cluster in a narrow field in conventional pb isotope diagrams 206pb 204pb 18 40 18 64 207pb 204pb 15 56 15 58 208pb 204pb 38 23 38 56 indicating a derivation from an isotopically homogeneous source on the 207pb 204pb versus 206pb 204pb diagram isotope compositions of the dikes plot slightly below the orogen curve suggesting contributions from mantle reservoir enriched by subducted oceanic lithosphere such a signature is typical of island arc magmatic rocks and supports the formation of the investigated rocks in a subduction related environment

structure and petrology of tauride ophiolites and mafic dike intrusions turkey implications for the neotethyan ocean cretaceous neotethyan ophiolites occur in four east west trending subparallel zones within the tauride tectonic belt in southern turkey the ophiolites of the inner intermediate and outer zones tectonically overlie the mesozoic platform carbonates of the tauride belt and are commonly underlain by a cenomanian ophiolitic melange these ophiolites consist mainly of tectonized mantle rocks mafic ultramafic cumulates and gabbros and commonly lack sheeted dike complexes and extrusive rocks of a complete ophiolite sequence metamorphic soles that are several hundred meters thick occur as thrust faulted slices beneath these ophiolites and show well developed metamorphic field gradients ophiolitic units and the metamorphic soles are intruded by mafic dike swarms that are truncated at the contact with the underlying melange unit dike rocks are made of subalkalic basalt to andesite typical of evolved island arc tholeiites they display large compositional variations with sio 2 content between 50 and 60 wt and mgo between 8 and 4 wt and contain higher ti augite phenocrysts and significantly less calcic plagioclase than their host cumulates the majority of the analyzed dike rocks show a slight depletion in light rare earth elements ree with low la smn ratios and are depleted in both high field strength hfs and heavy rees while enriched in large ion lithophile elements lile relative to normal mid ocean ridge basalt morb these characteristics suggest a mantle source that underwent previous melt extractions and subsequent metasomatism by lile and light ree enriched fluids geochemical modeling of trace elements shows that melting occurred at relatively low pressures under hydrous conditions and that it may have required the existence of an asthenospheric window in which the dike magmas developed through tapping and mixing of melts generated within a rising melting column starting slightly within the garnet stability field or in a transitional zone between the garnet and spinel stability fields at about 60 km depth this asthenospheric window was probably created during subduction of a neotethyan ridge system magmas ascending from the melt column within this window generated dikes that crosscut the metamorphic soles and were injected into the overlying mantle wedge and oceanic lithosphere the new 40 ar 39 ar hornblende dates of 92 90 ma and 90 91 ma from the metamorphic soles and dike swarms respectively show that evolution of these two geologic units was closely related in time and space and that they formed at the same intraoceanic subduction zone within the inner tauride seaway these data suggest that the tauride ophiolites within the three zones to the north originated from the same root zone situated north of the tauride carbonate platform and that they constitute remnants of a single ophiolitic nappe sheet derived from the inner tauride seaway within the neotethyan ocean

kinematics of late cretaceous subduction initiation in the neo tethys ocean reconstructed from ophiolites of turkey cyprus and syria formation of new subduction zones represents one of the cornerstones of plate tectonics yet both the kinematics and geodynamics governing this process remain enigmatic a major subduction initiation event occurred in the late cretaceous within the neo tethys ocean between gondwana and eurasia suprasubduction zone ophiolites i e emerged fragments of ancient oceanic lithosphere formed at suprasubduction spreading centers were generated during this subduction event and are today distributed in the eastern mediterranean region along three e w trending ophiolitic belts several models have been proposed to explain the formation of these ophiolites and the evolution of the associated intra neo tethyan subduction zone here we present new paleospreading directions from six upper cretaceous ophiolites of turkey cyprus and syria calculated by using new and published paleomagnetic data from sheeted dyke complexes our results show that nne ssw subduction zones were formed within the neo tethys during the late cretaceous which we propose were part of a major step shaped subduction system composed of nne ssw and wnw ese segments we infer that this subduction system developed within old triassic lithosphere along fracture zones and perpendicular weakness zones since the neo tethyan spreading ridge formed during gondwana fragmentation would have already been subducted at the pontides subduction zone by the late cretaceous our new results provide an alternative kinematic model of cretaceous neo tethyan subduction initiation and call for future research on the mechanisms of subduction inception within old and cold lithosphere and the formation of metamorphic soles below suprasubduction zone ophiolites in the absence of nearby spreading ridges

rapid fore arc extension and detachment mode spreading following subduction initiation most ophiolites have geochemical signatures that indicate formation by suprasubduction seafloor spreading above newly initiated subduction zones and hence they record fore arc processes operating following subduction initiation they are frequently underlain by a metamorphic sole formed at the top of the downgoing plate and accreted below the overlying suprasubduction zone lithosphere immediately following ophiolite formation paleomagnetic analyses of ophiolites can provide important insights into the enigmatic geodynamic processes operating in this setting via identification of tectonic rotations related to upper plate extension here we present net tectonic rotation results from the late cretaceous mersin ophiolite of southern turkey that document rapid and progressive rotation of ophiolitic rocks and their associated metamorphic sole specifically we demonstrate that lower crustal cumulate rocks and early dykes intruded into the underlying mantle section have undergone extreme rotation around ridge parallel shallowly plunging axes consistent with oceanic detachment faulting during spreading importantly later dykes cutting the metamorphic sole experienced rotation around the same axis but with a lower magnitude we show that these rotations occurred via a common mechanism in a pre obduction fore arc setting and are best explained by combining hyper extension resulting from detachment mode amagmatic suprasubduction zone spreading in a fore arc environment with a recently proposed mechanism for exhumation of metamorphic soles driven by upper plate extension available age constraints demonstrate that extreme rotation of these units was accommodated rapidly by these processes over a time period of 3 myr comparable with rates of rotation seen in oceanic core complexes in the modern oceans

timing of post obduction granitoids from intrusion through cooling to exhumation in central anatolia turkey abstract the middle to late cretaceous central anatolian granitoids intrude the supra subduction zone type central anatolian ophiolite and medium to high grade metasediments of central anatolian crystalline complex and are overlain by late palaeocene to early middle eocene sediments their single zircon 207 pb 206 pb evaporation ages define three clusters 1 cenomanian turonian weighted mean age 94 9 3 4 ma 2 turonian santonian 85 5 5 5 ma and 3 campanian 74 9 3 8 ma their hornblende and biotite 40 ar 39 ar and k ar cooling ages cluster around 80 65 ma the close hornblende and biotite ages reflect rapid exhumation of a mid crustal section during the campanian maastrichtian early to middle palaeocene 57 62 ma apatite fission track age clusters date the tail end of this exhumation episode it is proposed that the central anatolian granitoid melts were generated in a post collisional extensional setting following the docking of an oceanic island arc onto the tauride anatolide platform campanian maastrichtian to early middle palaeocene rapid exhumation event is considered to result from continent continent collisions between eurasian plate and the tauride anatolide platform along the izmir ankara erzincan suture zone

episodic formation of neotethyan ophiolites tibetan plateau snapshots of abrupt global plate reorganizations during major episodes of supercontinent breakup abstract neotethyan ophiolites along the bangong nujiang and yarlung tsangpo sutures tibetan plateau consist of mantle peridotite cumulates isotropic gabbro diabase plagiogranite and basaltic lava they comprise morb iab oib and boninitic rocks and mostly belong to supra subduction zone ssz type compositionally different rocks crystallized synchronously over a distance of 2000 km along the bangong nujiang and yarlung tsangpo sutures during the short periods of 190 182 and 132 120 ma respectively resembling the izu bonin mariana ibm proto arc the early jurassic bangong nujiang ophiolites formed in forearc settings during subduction initiation while the middle jurassic early cretaceous bangong nujiang ophiolites and the early cretaceous yarlung tsangpo ophiolites formed in forearc settings at pre existing subduction zones crystallization of the neotethyan ssz ophiolites from the eastern mediterranean middle east tibetan plateau to southeast asia and formation of the associated metamorphic rocks temporally coincided with major supercontinent breakup events 1 initial breakup of pangea in central atlantic and westernmost tethys 190 ma 2 separation of west and east gondwana 170 160 ma and initial opening of piemont ligurian tethys 175 164 ma 3 initial breakups of east and west gondwana 135 125 ma and 4 final breakup of gondwana 104 96 ma far field forces associated with abrupt global plate reorganizations may have triggered subduction initiation or transient interplate coupling decoupling at pre existing subduction zones leading to episodic formation of the neotethyan ssz ophiolites and rapid exhumation of metamorphic rocks in subduction zones the formation events of neotethyan ssz ophiolites and associated metamorphic rocks represent snapshots of global plate reorganizations during the major episodes of supercontinent breakup

the pre obduction to post obduction evolution of the sivas ophiolite turkey and implications for the precollisional history of eastern anatolia

early middle jurassic intra oceanic subduction in the izmir ankara erzincan ocean northern turkey abstract the izmir ankara erzincan suture zone near cankiri comprises an ophiolite related rock suite of amphibolite pyroxene amphibolite and epidote amphibolite the geochemical data reveal that the basaltic protoliths of the cankiri amphibolite suite are derived from different mantle sources amphibolites showing a lree enrichment in chondrite normalized ree pattern relatively high la n yb n 8 5 13 1 sm yb 2 8 3 7 ce sm 8 8 9 8 nb yb 14 4 20 5 th nb 1 1 2 6 originate from an oib like type i amphibolites mantle source those with flat chondrite normalized ree pattern low la n yb n 0 6 sm yb 1 0 ce sm 2 7 nb yb 0 6 suggest derivation from a depleted morb like type ii amphibolites mantle source a third type of amphibolite is characterized by la n yb n 1 54 sm yb 1 1 ce sm 4 5 nb yb 1 1 and th nb 0 3 it is derived from an enriched morb source and shows characteristics similar to island arc basalts amphiboles from these rocks yielded 40 ar 39 ar plateau ages between 177 08 0 96 ma and 166 9 1 1 ma these dates are interpreted as metamorphic ages of the amphibolitic rocks they differ significantly from previous ages of amphibolitic rocks the metamorphic sole rocks related to turkish ophiolites however similar metamorphic ages have been reported for metamorphic sole rocks of the hellenic dinaric ophiolites further west the metamorphic sole rocks have been generated in intra oceanic environments via intra oceanic subduction thrusting events the new age data of the cankiri amphibolite suite suggest that the izmir ankara erzincan ocean was subducted around early middle jurassic times i e roughly coeval with the oceanic basin s generating the hellenic dinaric ophiolites in the early middle jurassic time the tectonic regime in the izmir ankara erzincan ocean was compressional and the ocean was closing at that time the new age data presented here could imply that jurassic granites which cross cut basement rocks of the pontides are related to the northward subduction of the izmir ankara erzincan ocean during jurassic time

non marine sedimentation associated with oligocene recent exhumation and uplift of the central taurus mountains s turkey abstract three related basins in southern turkey the ecemis basin the karsanti basin and the aktoprak basin document the neogene recent regional exhumation and surface uplift history of the central taurus mountains the regional tectonic framework was established by a late eocene phase of compressional deformation that ended tethys related marine deposition during the oligocene early miocene non marine sedimentation was dominantly from braided rivers flowing from the nascent taurus mountains and from the nigde metamorphic massif further north during this period erosion more or less kept pace with exhumation and the topography remained subdued allowing a marine incursion probably eustatically controlled into the karsanti basin in the east during early oligocene time regional exhumation was possibly controlled by thermal uplift of an actively extending area located behind the subducting s neotethys in the eastern mediterranean sea during exhumation largely ophiolitic rocks were eroded revealing the deformed mesozoic tauride carbonate platform beneath the area was affected by a short lived pulse of compressional deformation transpression probably in mid miocene time but extensional exhumation then resumed as indicated by the presence of metamorphic derived clasts from the adjacent nigde massif late miocene deposition was dominated by large inward draining lakes consistent with regional evidence of a humid climate during this time strong surface uplift took place during plio quaternary time drainage to the mediterranean became established allowing river valleys to incise deeply into the flanks of the taurus mountains palaeo valleys were successively infilled with coarse alluvial sediments this deposition was influenced by ne sw trending extensional faults in addition the sedimentary evolution of the area was strongly influenced by the nne ssw trending ecemis fault zone which has experienced ca 60 km of left lateral strike slip since the late eocene an important pulse of normal faulting transtension in latest miocene early pliocene time generated large fault scarps these acted as sources for large plio quaternary alluvial fans which prograded across active strike slip faults the morphology of these fans was influenced by a combination of quaternary climatic change axial fluvial downcutting and active strike slip tectonics in general the plio quaternary regional uplift of the taurus mountains may relate to underplating of material derived from the african plate during progressive collision with the anatolian eurasian plate in the vicinity of the easternmost mediterranean sea

geochemical 40ar 39ar age and isotopic data for crustal rocks of the neyriz ophiolite iran trace element data including the rare earth elements in the crustal sequence of the neotethyan neyriz ophiolite in southwest iran indicate normal mid ocean ridge basalt n morb or island arc tholeiite chemistry for the tang e hana basalt the data suggest that the tang e hana rhyodacite basalt plagiogranite and gabbro derived from a low k tholeiitic parent magma trace element distributions in amphibolite clasts in the sole detachment of the ophiolite south of lake neyriz correlate well with distributions in basalt clasts in the melange and in the tang e hana basalt these trace elements suggest that the amphibolite originated from metamorphism and deformation of a tholeiitic basalt protolith new 40 ar 39 ar incremental heating plateau ages from two hornblende plagiogranite specimens in the crustal sequence in tang e hana are 92 07 1 69 and 93 19 2 48 ma isotopic data for five tang e hana basalts yield end values of 7 8 and 7 9 and 87 sr 86 sr values of 0 70368 to 0 70476 the isotopic compositions ophiolite tectonostratigraphy and correlation of the 40 ar 39 ar cooling plagiogranite and deformation amphibolite ages suggest emplacement of the neyriz ophiolite either into an accretionary prism through offscraping and subduction erosion and or formation in a supra subduction zone environment around 82 96 ma progressive accretion probably led to the de velopment of a fore arc basin and deposition of upper cretaceous eocene fore arc and arc derived sediments on the ophiolite resume des donnees sur les elements traces incluant les terres rares dans la sequence crustale de l ophiolite neo tethysienne de neyriz dans le sud ouest de l iran indiquent que le basalte de tang e hana est de type basalte oceanique de type n n morb ou une tholeiite d arc insulaire les donnees recueillies suggerent que la rhyodacite le basalte le plagiogranite et le gabbro de tang e hana proviennent d un magma tholeiitique parent a faible teneur potassique la repartition des elements traces dans les clastes amphiboliques dans l unique portion separee de l ophiolite au sud du lac neyriz est en bonne correlation avec celle trouvee dans les clastes basaltiques du melange ophiolitique et du basalte de tang e hana ces elements traces laissent penser que l amphibolite provient du metamorphisme et de la deformation d un protolithe de basalte tholeiitique de nouveaux ges 40 ar 39 ar par paliers de temperature pour deux specimens de plagiogranite a hornblende appartenant a la sequence crustale de tang e hana ont donne des valeurs de 92 07 1 69 ma et de 93 19 2 48 ma des donnees isotopiques de cinq basaltes de tang e hana ont donne des valeurs end de 7 8 et de 7 9 et des valeurs 87 sr 86 sr de 0 70368 a 0 70476 les compositions isotopiques la tectonostratigraphie ophiolitique et la correlation entre les ges 40 ar 39 ar de refroidissement plagiogranite et de deformation amphibolite laissent croire que l ophiolite de neyriz a ete mise en place dans le prisme d accretion sous l effet de l ecaillage et de l erosion par subduction et ou s est formee au sein d un environnement a zone de supra subduction il y environ 82 ma a 96 ma l accretion graduelle a probablement conduit au developpement d un bassin d avant arc et au depot de sediments provenant de l avant arc et de l arc sur l ophiolite au cours du cretace superieur et de l eocene

tectonostratigraphic evolution of the upper cretaceous cenozoic central anatolian basins an integrated study of diachronous ocean basin closure and continental collision

geochemistry and tectonic significance of metamorphic sole rocks beneath the beysehir hoyran ophiolite sw turkey abstract the beysehir hoyran ophiolite is situated in the western part of the tauride belt sw turkey and crops out at two localities north of the lake beysehir it mainly comprises harzburgitic peridotites that were tectonically emplaced to their present position during the late eocene the ophiolites themselves are tectonically overlain by either slope basin deposits with lava blocks egirler formation or massive triassic limestone blocks deliktas formation high grade sub ophiolitic metamorphic rocks i e epidote amphibolite amphibolite and pyroxene amphibolite together with minor quartzite and calcschist are observed at the base of the ophiolite sequence where they occur as thin tectonic slices with an inverted metamorphic gradient average p t conditions of 630 770 c and c 6 1 5 kbar are calculated for the metamorphism of the amphibolites by conventional geothermobarometry corresponding to a burial depth of 18 20 km both the sub ophiolitic metamorphic rocks and the overlying mantle tectonites were intruded by isolated tholeiitic nb y 0 041 0 108 diabase dikes which do not transect the tectonic contact between the two units geochemical investigations of the amphibolites of the sub ophiolitic rock suite show two different geochemical affinities with the first group being alkaline in character nb y 1 3 86 and the second one being tholeiitic nb y 0 064 0 13 ree patterns trace element plots and tectonomagmatic discrimination diagrams indicate that the most probable protoliths for alkaline amphibolites are within plate type alkali basalts whereas those of the tholeiitic group resemble tholeiitic island arc basalts similarities between the geochemical characteristics of the amphibolites and those of the volcanic rocks of the egirler formation strongly suggest that the latter are the protoliths of the amphibolites

island arc tholeiite to boninitic melt evolution of the cretaceous kizildag turkey ophiolite model for multi stage early arc forearc magmatism in tethyan subduction factories article i nfo the kizildag ophiolite in turkey is a remnant of the late cretaceous suprasubduction zone ssz oceanic lithosphere that was developed in southern tethys and is part of a peri arabian ophiolite belt including the troodos cyprus baer bassit syria and semail oman ophiolites in the eastern mediterranean region the internal structure petrology and geochemistry of the kizildag intrusive and extrusive rocks show a magmatic progression from island arc tholeiite iat to boninitic compositions similar structural architecture and geochemical trends in the coeval troodos and baer bassit ophiolites suggest that this multi stage ssz magmatism was common in most tethyan ophiolites the sheeted dikes and the majority of extrusive rocks in kizildag are composed of basalt basaltic andesite and andesite with relatively low la smn 0 5 0 7 low mgo 7 9 wt and high tio2 0 7 1 0 wt and exhibit high dy ybn ratios these iat suites also include rare younger dacitic dikes showing strong enrichment in the lree the late stage basaltic dikes and lavas sakalavites have high la smn 0 8 1 0 high mgo 9 11 wt and low tio2 0 3 0 4 wt contents and display strong depletion in both lree and hree this suite of rocks represents the boninitic component of the kizildag ophiolite that developed from shallow and greater degrees of melting of hydrous and highly refractory peridotites beneath the extended forearc environment the progressive evolution of kizildag magmas from iat to boninitic compositions in time and space was a result of variable mixing aggregation and differentiation of geochemically different melt batches which formed in different levels polybaric within the melting column rapid slab rollback induced corner flow mantle return flow and asthenospheric diapirism providing more fertile melt directly affected the evolution of this melting column and may have triggered advanced degrees of shallow melting of the hydrous and highly depleted forearc mantle producing refractory liquids of the boninitic stage these geochemical patterns of the kizildag ophiolite reflect a multi stage evolution of ssz magmatism in tethyan subduction factories that is analogous to the earlier arc volcanism in the eocene oligocene izu bonin mariana system

sedimentary development of the oligocene karsanti basin southern turkey in its regional tectonic setting abstract following late cretaceous ophiolite and melange emplacement within the tauride belt several neogene sedimentary basins of variable size were formed along the southern flank of the taurus continent in southern turkey these include the pozanti and karsanti basins and the regional scale cukurova basin complex extending southwestwards into the cilicia kyrenia basin the karsanti basin is bounded by the regional scale sinistral ecemis fault zone to the west the east anatolian fault zone to the southeast and the negoene adana basin to the south deformed palaeozoic and mesozoic rock units that display an irregular palaeotopography form the basement of the karsanti basin these units are overlain by an allochthonous kizildag melange and by thrust slices of basic ultrabasic ophiolitic rocks farasa ophiolites that were emplaced in this region during the late maastrichtian the karsanti basin was formed during the oligocene above the thrust sheets the karsanti basin disconformably overlies the ophiolitic nappes and is interpreted as a n s trending half graben which was probably most active following the deposition of lacustrine sediments during the late oligocene the main karsanti basin infill is represented by four lithological units 1 alluvial fan deposits a1 2 shallow marine deposits a2 3 lacustrine deposits a3 and 4 fluvial deposits a4 these sediments were deposited during the oligocene prior to the initiation of the main adana basin which formed in a separate intermontane setting the karsanti basin fill is unconformably overlain by early miocene sediments of the neogene adana basin