magnetostratigraphy of late miocene continental deposits in samos greece abstract we present a detailed magnetostratigraphic study of the upper part of the mytilini formation marker tuffs and main bone beds of samos island greece seven successive polarity zones have been identified and a correlation with the geomagnetic polarity time scale has established that the sediments of this section were accumulated between 5 7 and 6 8 ma according to these results the upper mammalian fossiliferous levels are found within the reversed polarity zone lying in the time interval 6 1 6 4 ma

origin of the lethal gas burst from lake monoun cameroun abstract on 15 august 1984 a lethal gas burst issued from a submerged 96 m deep crater in lake monoun in cameroun western africa killing 37 people the event was associated with a landslide from the eastern crater rim which slumped into deep water waters below 50 m are anoxic dominated by high fe 2 600 mg l and hco 3 1900 mg l anoxic and supersaturated with siderite which is a major component of the crater floor sediments the unusually high fe 2 levels are attributed to reduction of laterite derived ferric iron gradually brought into the lake as loess and in river input sulfur compounds are below detection limits in both water and gas gases effervescing from depressurized deep waters are dominantly co 2 with minor ch 4 having 13 c of 7 18 and 54 8 per mil respectively bacterial decomposition of organic matter may account for the methane but 14 c of lake water indicates that only 10 of the carbon is modern giving an apparent age of 18 000 years the dominant source of carbon is therefore attributed to long term emission of co 2 as volcanic exhalation from vents within the crater which led to gradual build up of hco 3 in the lake the density stratification of the lake may have been upset by an earthquake and underwater landslide on 15 august which triggered overturn of the lake and caused nucleation of co 2 in the deep water the resultant ebullition of co 2 from deep lake waters led to a gas burst at the surface and locally generated a water wave up to 5 m high people travelling through the gas cloud were asphyxiated presumably from co 2 and suffered skin discoloration from unidentified components

error analysis for the determination of tectonic rotation from paleomagnetic data appendix b is available with entire article on microfiche order from american geophysical union 2000 florida avenue n w washington d c 20009 document b83 001 2 50 payment must accompany order recent determinations of tectonic rotation and flattening from paleomagnetic data have exaggerated the size of the confidence limits or error bars by about 25 this has been caused by the misuse of conventional error propagation formulas to derive one degree of freedom error bars from a two dimensional cone of confidence 95 an analytical calculation which is valid when error bars are small shows that the correct error bars are 75 to 80 of the values derived in previous studies i have used numerical integration to check on the applicability of the analytical solution and to calculate error bars when the analytical approximation cannot be used the analytical approximation may be used whenever 95 is less than 10 and the mean inclination is not too close to vertical confidence limits given for tectonic rotation and flattening in recent literature are too large and should be reduced by 20 25 narrowing the error bars in this way permits a more accurate interpretation of paleomagnetic data

regional seismic wave propagation lg and sn and pn attenuation in the arabian plate and surrounding regions an edited version of this paper was published by blackwell publishing copyright 2004 blackwell publishing see also http www blackwell synergy com doi abs 10 1111 j 1365 246x 2004 02246 x http atlas geo cornell edu middleeastnorthafrica publications al damegh2004 htm

witness accounts of the catastrophic event of august 1986 at lake nyos cameroon abstract the catastrophic event at lake nyos in august 1986 has resulted in a major scientific debate concerning its origin and how to prevent new casualties of this nature in future we have tried in the present paper to interrelate the testimonies in time and place and to interpret them in geological terms it has been possible to draw a hazard map of the catastrophe and reconstruct the sequence of the events it began on august 20 1986 with minor upwelling of hot water on august 21 1986 a small explosion occurred in lake nyos followed in the evening by an intermittent jet of water topped by a white plume at 10 p m a major detonation occurred in the lake and carbon dioxide invaded the low lying valleys killing more than 1500 people and 6000 head of cattle the all scientific community agree gases have a magmatic origin two scenarios have been used to describe the catastrophe the volcanic origin scenario a gas jet splitted across the lake water and the limnic origin scenario gases were stored in the lake water and an internal or external phenomenon triggered the degassing in the volcanic origin scenario prevention of degassing is impossible any volcanic area can present this danger in or outside lakes prediction will proceed with usual methods in the limnic scenario both prediction and prevention are possible the only dangerous area are located around lakes containing dissolved gases prevention can be obtain by pumping and degassing the deep waters to the surface in the present paper testimonies have been used to test both hypotheses

eastern turkish high plateau as a small turkic type orogen implications for post collisional crust forming processes in turkic type orogens abstract post collisional magmatism may be generated by extensive crustal melting in tibet type collisional environments or by falling out of slabs from under giant subduction accretion complexes in turkic type collisional orogens giving rise to decompression melting of the asthenospheric mantle replacing the removed oceanic lithosphere in turkic type post collisional magmatism the magmatic products are dominantly alkalic to peralkalic and greatly resemble those of extensional regions giving rise to much confusion especially in interpreting old collisional orogenic belts such magmatic regions are also host to a variety of economically valuable ore deposits including gold one place in the world where today active turkic type post collisional magmatism is present is the eastern anatolian high plateau produced after the terminal arabia eurasia collision in the late miocene the plateau is mostly underlain by the late cretaceous to oligocene east anatolian accretionary complex which formed south of the rhodope pontide magmatic arc this subduction accretion complex has been further shortening since the collision but it has also since been domed and became almost entirely covered by at least 15 000 km3 of volcanic rocks the volcanic rocks are calc alkalic in the north transitional in the middle and alkalic in the south of the plateau where the crust is thinnest today less than 38 km the volcanics are derived almost entirely from an enriched mantle the ages of the volcanics also become younger from north to south from about 11 ma to possibly 17th century ad we interpret the origin of the magmatic rocks as the result of decompression melting of the asthenospheric mantle sucked towards the exposed base of the east anatolian accretionary complex as the oceanic lithosphere beneath it fell out the lower density of the hot asthospheric material was the cause of the doming we believe that similar processes dominated the post collisional tectonics of such vast turkic type orogens as the altaids of central asia the late devonian early carboniferous lachlan belt in southeastern australia and the pan african collage of northeast afro arabia it is likely that archaean collisions were dominated by turkic type post collisional events rather than tibetan ones that only became common in the proterozoic

palaeomagnetic study of the karaman and karapinar volcanic complexes central turkey neotectonic rotation in the south central sector of the anatolian block abstract in the anatolian sector of the afro eurasian collision zone a palaeotectonic collisional phase paleocene to miocene responsible for emplacement of the pontide and tauride orogens has been replaced by a neotectonic phase of continental deformation late miocene early pliocene to recent the latter phase appears to have been accommodated mainly by crustal thickening during late miocene and pliocene times but was succeeded by complex differential rotations of fault blocks during crustal extrusion in late pliocene and quaternary times in this study we have investigated palaeomagnetism of miocene recent volcanic rocks comprising the western extension of the central anatolian volcanic province located in the south central part of the anatolian block with the aim of resolving deformations near to the border with the tauride orogen rock magnetic investigations identify low ti magnetite assemblages of primary cooling related origin these have predominant multidomain structures but significant fractions of single domains are always present low temperature alteration is largely absent the karaman volcanic complex late pliocene shows a net rotation of 5 7 6 9 not significantly different from the regional field axis during recent times the karapinar volcanic field brunhes epoch identifies a larger net rotation of 23 1 12 0 in a restricted sample the adjoining karacadag volcanic complex late miocene pliocene and middle miocene lavas beneath the hasandag complex define net rotations of 8 1 5 9 and 16 4 8 9 respectively analysis of palaeomagnetic results from late cretaceous recent rock units emplaced in anatolia during the palaeotectonic and neotectonic regimes shows that rates of rotation have accelerated in post pliocene times as crustal thickening has given way to tectonic escape a near uniform anticlockwise rotation of 25 35 has characterised much of this block during the most recent phase of deformation and appears to have occurred in common with the eurasian plate to the north of the north anatolian fault zone whilst this rotation appears to extend south eastwards across the ecemis fault zone towards the east anatolian fault the present study shows that smaller differential anticlockwise rotations have characterised the south central region of the block where it has interacted at its southwestern margin with oroclinal bending focussed on the isparta angle

the lake nyos disaster model calculations for the flow of carbon dioxide abstract in order to explain the origin of the lake nyos disaster a three dimensional model for carbon dioxide flow has been calculated the boundary conditions were based on the field observations calculations show that co2 tends to flow down slope by gravity and velocity tends to increase on steep slopes the results of calculation are in good agreements with the effects observed in the field the initial velocity of the gas jet should have been 28 m s the volume of pure co2 0 6 km3 and the gas release should occur in a very short time a few minutes the gas was released as a jet half way from the center on the south south west side of the lake

paleomagnetic evidence for rotation in opposite senses of adjacent blocks in northeastern aegea and western anatolia paleomagnetic data from western anatolia and from the island of lesbos demonstrate significant counterclockwise clockwise or null rotations of coherent blocks which occurred during the neotectonic period these results suggest that the brittle carapace of the lithosphere may not everywhere follow the motion of the ductile lower part but that its movement arises from adjustment to the extensional tectonic regime

new paleomagnetic data from oligocene formations of northern aegea new paleomagnetic data obtained from volcanic and plutonic formations in thrace northern aegea show that this region has not undergone any significant rotation since the lower oligocene the mean value of the inclination is shallower than expected on the basis of a geocentered dipole field implying a large northward drift of about 1000 km although a comparison with published data from bulgaria leads to a puzzling large shortening between these two regions the measured shallow inclinations are coherent with most of other paleomagnetic studies from oligocene formations throughout the entire mediterranean area together with published results from chalkidiki peninsula our data suggest that the circum rhodopean belt was almost rectilinear and trending e w in lower oligocene time

neotectonic deformation in the western sector of tectonic escape in anatolia palaeomagnetic study of the afyon region central turkey abstract following final closure of the neotethyan ocean during the late miocene deformation in central turkey has led to crustal thickening and uplift to produce the anatolian plateau followed by westward extrusion of terranes by strike slip widespread volcanism has accompanied this latter neotectonic phase and palaeomagnetic study of the volcanism shows a coherent record of differential block rotations indicating that the anatolian region is not a plate or platelet sensu stricto but is undergoing distributed internal deformation to evaluate the scale of neotectonic rotations in the transition zone near the western limit of tectonic escape and the border of the extensional domain in central west turkey we have studied the palaeomagnetism at 82 sites in volcanic suites distributed along a 140 km lineament with north south trend and ranging in age from 18 to 8 ma comparable deflection of magnetic remanence from the present field direction is identified along the full length of the lineament a mean clockwise rotation of 12 3 4 2 is determined for this western sector of the anatolian strike slip province since similar rotations are observed in the youngest and oldest units this cumulative rotation occurred after the late miocene when interpreted together with results elsewhere in anatolia it is inferred that the rotation is later than crustal thickening and uplift of the anatolian plateau and entirely a facet of the tectonic escape inclinations are mostly 10 shallower than the predicted miocene field and are considered to reflect the presence of a persistent inclination anomaly in the mediterranean region larger rotations departing from the regional trend are also observed within the study region but are confined to the vicinity of major faults notably those bounding the afyon aksehir graben the pattern of neotectonic declinations across anatolia identifies strong anticlockwise rotation in the east near the arabian pincer with progressive reduction in the amount of rotation towards the west it becomes zero or slightly clockwise at the western extremity of the accreted terrane collage rotations also appear to become generally younger towards the south crustal deformation has therefore been distributed and the net effect of terrane extrusion to the west and south has been to expand the curvature of the tauride arc the westward radial expansion of the extruded terranes is inferred to combine with backroll on the hellenic arc to produce the contemporary extensional province in western turkey

geochemical features of collision related volcanic rocks in central and eastern anatolia turkey in central and eastern anatolia volcanism related to continental collision occurred in neogene to quaternary times major and trace element compositions 87sr86 sr and k ar ages were determined for volcanic rocks from selected volcanoes in this region 87sr86 sr for basalts from erciyes volcano in the eastern part of central anatolia as well as ararat nemrut and karacadag volcanoes in eastern anatolia are in the range 0 7035 0 7040 these ratios are higher than those of n type morb but overlap arc volcanic rock values this suggests that the mantle source which was possibly contaminated by fluids and melts with higher87sr86 sr during the pre collisional events has similar sr isotopic compositions in wide areas of the eastern part of central anatolia and eastern anatolia even across the collision plate boundary in addition chemical compositions of the mantle source are not homogeneous with respect to hfs element contents indicating that the slab derived components resulting from past subductions are not homogeneously distributed the mantle source beneath the western part of central anatolia which corresponds to the transitional region from collision tectonics in the east to subduction tectonics in the west has different chemical and sr isotopic signatures from other parts of anatolia in the western part of central anatolia the87sr86 sr of basaltic rocks from three regions characterized by monogenetic volcanoes are in the range 0 70427 to 0 70581 and differ from region to region in spite of indistinguishable chemical compositions this indicates either source heterogeneity on a small scale or different contributions of local crustal contaminants calc alkaline lavas from ararat and kars in eastern anatolia have chemical compositions with subduction signatures inherited from pre collision subduction events in contrast the chemical and sr isotopic features of volcanic rocks from erciyes volcano in central anatolia indicate that the combined process of fractional crystallization of basaltic magma and crustal assimilation without injection of slab derived components is the dominant process generating calc alkaline andesite under the collision tectonics regime operating in this region

eocene development of the northerly active continental margin of the southern neotethys in the kyrenia range north cyprus we focus on an active continental margin related to northwards subduction during the eocene in which sedimentary melange olistostromes forms a key component maastrichtian early eocene deep marine carbonates and volcanic rocks pass gradationally upwards into a thick succession 800 m of gravity deposits exposed in several thrust sheets the lowest levels are mainly siliciclastic turbidites and debris flow deposits interbedded marls contain middle eocene planktonic benthic foraminifera and calcareous nannofossils sandstones include abundant ophiolite derived grains the higher levels are chaotic debris flow deposits that include exotic blocks of late palaeozoic mesozoic neritic limestone and dismembered ophiolite related rocks a thinner sequence 200 m in one area contains abundant redeposited paleogene pelagic limestone and basalt chemical analysis of basaltic clasts shows that some are subduction influenced basaltic clasts from unconformably overlying alluvial conglomerates late eocene oligocene indicate derivation from a supra subduction zone ophiolite including boninites taking account of regional comparisons the sedimentary melange is interpreted to have formed within a flexurally controlled foredeep floored by continental crust gravity flows including large limestone blocks multiple debris flows and turbidites were emplaced followed by southwards thrust imbrication the emplacement was possibly triggered by the final closure of an oceanic basin to the north alanya ocean further convergence between the african and eurasian plates was accommodated by northwards subduction beneath the kyrenia active continental margin subduction zone rollback may have triggered collapse of the active continental margin non marine to shallow marine alluvial fans prograded southwards during late eocene oligocene time marking the base of a renewed depositional cycle that lasted until latest miocene time

regional wave propagation in turkey and surrounding regions this paper was published by the american geophysical union agu copyright 2000 agu see also http www agu org journals gl gl0003 1999gl008375 pdf 1999gl008375 pdf http atlas geo cornell edu turkey publications gok et al 2000 htm

magma generation by slab steepening and breakoff beneath a subduction accretion complex an alternative model for collision related volcanism in eastern anatolia turkey 1 eastern anatolia is regarded as one of the best examples of continental collision represented by a 2 km high plateau it displays shallow and diffuse seismicity indicating that the crust is still being actively deformed perhaps the most striking aspect of eastern anatolia is the volume and compositional variability of collision related volcanic products erupted during the neogene and quaternary time a number of models have been proposed for the genesis of this volcanism in the region however recent geophysical studies have revealed that a mantle lithosphere is almost completely absent beneath a greater portion of the region which makes us question the validity of the previous models in this paper we propose a new model for magma genesis slab steepening and breakoff beneath a large subduction accretion complex this model holds that a northward subducting oceanic lithosphere beneath the eastern anatolia accretionary prism gets steepened and eventually detached from the continental lithosphere of the bitlis poturge massif following the continent accretionary complex collision this brings the asthenospheric mantle in contact with the accretionary complex at shallow depths e g around 50 km resulting in rapid regional uplift and extensive melting which leads to collisional volcanism

palaeosecular variation over the past 5 myr based on a new generalized database summary a generalized database of global palaeomagnetic data from 3719 lava flows and thin dykes of age 0 5 ma has been constructed for use with a relational database management system the database includes all data whose virtual geomagnetic poles vgp lie within 45 of the spin axis and can be used for studies of palaeosecular variation and for geomagnetic field modelling because many of these data were collected and processed more than 15 20 years ago each result has been characterized according to the demagnetization procedures carried out analysis of these data in terms of the latitude variation of the angular dispersion of vgps palaeosecular variation from lavas strongly suggests that careful data selection is required and that many of the older studies may need to be redone using more modern methods differences between the angular dispersions for separate normal and reverse polarity data sets confirm that many older studies have not been adequately cleaned magnetically therefore the use of the database for geomagnetic field modelling should be carried out with some caution using a vgp cut off angle that varies with latitude the best data set consists of 2636 results that show a smooth increase of vgp angular dispersion with latitude model g for palaeosecular variation which is based on modelling of the antisymmetric dipole and symmetric quadrupole dynamo families provides a good fit to these results

late palaeozoic early cenozoic tectonic development of the eastern pontides artvin area turkey stages of closure of tethys along the southern margin of eurasia

late palaeozoic early cenozoic tectonic development of southern turkey and the easternmost mediterranean region evidence from the inter relations of continental and oceanic units

the eastern turkey seismic experiment the study of a young continent continent collision during the last 10 20 million years the tectonics of turkey and the anatolian plateau can be described as the convergence of three continental plates the anatolian arabian and eurasian plates form a diverse suite of tectonic boundaries this tectonic environment makes the east anatolian plateau and bitlis suture an excellent natural laboratory to study the early stages of continental collision and its consequences until now the only well studied example for active continental collision has been that of india colliding with eurasia and the subsequent uplift of the tibetan plateau

geophysical investigation of the geothermal potential under the largest volcanic cover in anatolia kars plateau ne turkey in this study curie point depth cpd geothermal gradient radiogenic heat production and heat flow maps were constructed based on different thermal conductivity coefficients using magnetic anomaly data for the kars plateau which has the largest volcanic cover in turkey the bottom depths of the magnetic crust in the research area were revealed by the cpd map for the first time in this investigation there are two apparent magnetic anomaly trends in the study area the first is the horasan senkaya sarikamis selim arpacay trend in the ne sw direction and the other is the hanak ardahan arpacay trend in the nw se direction two other prominent elongations extend into the ardahan gole senkaya and kars digor axes all these trends represent mountain chains and or stratovolcanoes in the region and no anomalies are observed around the non volcanic outcrops curie depths are shallow up to 14 km between horasan and kagizman towns and 12 km in the northwestern part of the study area gradient values can reach 50 c km 1 in the northwestern sector together with the high heat flows represented by the 150 wm 1 k 1 contours the deepest cpd region lies between gole and susuz towns where the geothermal gradient decreases to 27 c km 1 heat flows decrease 60 wm 1 k 1 in the same area an apparent gap around the kars plateau was observed in previous regional heat flow maps of turkey by other authors who used the bottom hole temperatures of boreholes and hot springs temperatures this gap has been accurately filled from the results of this study and geothermal exploration areas and the geothermal potential of the kars plateau have thus been determined for future exploration activity on the basis of the tectonic elements and earthquake data

southeast anatolian orogenic belt revisited geology and evolution the southeast anatolian orogenic belt consists of the arabian platform a zone of imbrication and a nappe zone the arabian platform is represented by a thick marine succession the zone of imbric

exploding lakes and maleficent water in grassfields legends and myth abstract in august 1984 lake manoun exploded killing 37 people in august 1986 lake nyos exploded killing more than 1700 people both explosions occurred in the rainy season two years and six days apart have there been similar explosions in the cameroon grassfields in the past this paper argues that such explosions have occurred and have been recorded in area folklore in the form of migration stories that point unmistakably to the maleficent activities of lakes and other bodies of water two migration stories are considered and compared an ephemeral exploding lake that destroys the bamessi people in the kom story and a crater lake in the oku story in which the lake is said to have left its bed to destroy the people of kijem in examining the category of maleficent water several types of potentially maleficent water are considered including indigenous classifications of lakes as good or bad and stories about devils or witches associated with water all suggest that the folklore motif of dangerous destructive water may have its basis in observed fact while this evidence is not conclusive it is highly suggestive and in combination with evidence that the area around nyos is very recently settled it lends credence to the supposition that the crater lakes of the area may have a life cycle that involves changes of sometimes stupendous often dangerous proportions

distributed neotectonic deformation in the anatolides of turkey a palaeomagnetic analysis abstract the palaeotectonic phase of deformation in anatolia accompanied closure of the tethyan ocean and was finally completed with sealing of the bitlis suture bordering the arabian shield at 12 ma arabia has since continued to indent the collage of terranes accreted to the eurasian margin by differential northward movement relative to africa along the dead sea fault zone and counterclockwise ccw rotation accompanying the opening of the red sea this neotectonic phase of deformation has accompanied uplift of the anatolian plateau and establishment of intracontinental transforms comprising the north and east anatolian fault zones deformation has included extrusion and rotation of blocks away from the arabian syntaxis by tectonic escape we produce an updated summary of palaeomagnetic results from this region to show that deformation has been distributed so that block rotations vary systematically across anatolia ranging from strongly ccw in the zone of high strain north of the arabian indenter to near zero in central anatolia and then progressively cw in western anatolia new palaeomagnetic results from the ankara igneous district are also reported and help to constrain the east to west change from ccw to cw rotation within central anatolia the transition of tectonic regimes from compression in the east to extension in the west involves the expulsion of blocks and their rotation along arcuate strike slip faults at an acute angle to the maximum compressive stress 1 between arabia and eurasia the comparable distribution of rotations in palaeotectonic and neotectonic units indicates that the bulk of the observed palaeomagnetic rotations have been concentrated within the last plio pleistocene phase of the neotectonic era as is found in the aegean domain to the west and has involved blocks of the order of 100 km in size the weak collage of accretionary terranes sandwiched between the arabian indenter and the eurasian margin now defined by the north anatolian fault zone has evidently taken up the bulk of the strain imparted by the continuing northward motion of arabia to expand the radius of the tauride arc and the perimeter of extruded crust bordering the limit of the extensional province in western turkey the distributed character of neotectonic deformation is illustrated by equivalent polar distributions both palaeotectonic and neotectonic palaeomagnetic poles show arcuate distributions with poles to best fitting small circles focussed close to the study area differences between the distributed neotectonic deformation resolved from palaeomagnetism and the contemporary gps record reflect the contrasting time periods being evaluated the palaeomagnetic record incorporates evolving and changing tectonic regimes whereas the gps signature has no long term validity within the weak anatolian collage hence the full spectrum of techniques for resolving neotectonic deformation is relevant to unravelling deformation in such regions

present day kinematics of the middle east and eastern mediterranean the middle east and eastern mediterranean regions contain three major strike slip fault zones the dead sea fault zone dsfz and the north and east anatolian fault zones nafz and eafz these accommodate northward motion of the african and arabian plates relative to eurasia and westward motion of the small turkish plate this study deduces an internally consistent solution for the present day kinematics of these plates which is accurate to better than 20 and applicable throughout time since 5 ma by constraining the slip senses and rates on these strike slip fault zones the 7 0 5 mm yr 1 left lateral slip rate on the dsfz is associated with counterclockwise rotation of arabia relative to africa at 0 33 m y 1 around an eulcr pole near 33 n 23 e the nafz takes up counterclockwise rotation of the turkish plate relative to eurasia at 0 83 m y 1 13 around a pole at 31 n 35 5 e with right lateral slip rate 15 mm yr 1 the resulting prediction for the eafz involves 14 mm yr 1 left lateral motion and 2 mm yr 1 of shortening between arabia and turkey the triple junction of africa arabia and turkey is near the city of kahramanmaras this locality contains a narrow promontory bounded by ssw trending left lateral faults at the edges of the arabian and turkish plates which is loosely attached to the african plate moving westward relative to its interior at 4 mm yr 1

p wave tomography of the mantle under the alpine mediterranean area 1 we study the upper mantle p wave velocity structure below the euro mediterranean area down to 1000 km depth by seismic travel time tomography we invert summary residuals constructed with both regional and teleseismic first arrival data reported by the international seismological centre isc 1964 1995 introducing some alternative strategies in the travel time tomographic approach and a new scheme to correct teleseismic data for global mantle structure our high resolution model pm0 5 is parameterized with three dimensional 3 d linear splines on a grid of nodes with 0 5 spacing in both horizontal directions and 50 km vertical spacing we obtain about 26 root mean square rms reduction of residuals by inversion in addition to roughly 31 reduction after summary rays formation and selection sensitivity analyses are performed through several test inversions to explore the resolution characteristics of the model at different spatial scales the distribution of large scale fast anomalies suggests that two different stages of a convection process presently coexist in very close regions the mantle dynamics of western central europe is dominated by blockage of subducted slabs at the 660 km discontinuity and ponding of seismically fast material in the transition zone contrarily in the eastern mediterranean fast velocity material sinks into the lower mantle suggesting that the flow of the cold downwelling here is not blocked by the 660 km discontinuity on a smaller scale the existence of tears in the subducted slab lithospheric detachment all along both margins of the adriatic plate as proposed by some authors is not supported by our tomographic images

tomographic pn velocity and anisotropy structure beneath the anatolian plateau eastern turkey and the surrounding regions an edited version of this paper was published by the american geophysical union agu copyright 2003 agu see also http www agu org pubs crossref 2003 2003gl017391 shtml http atlas geo cornell edu turkey publications al lazki et al 2003 htm

mechanisms of the nyos carbon dioxide disaster and of so called phreatic steam eruptions abstract during the night of august 21 1986 a huge volume of concentrated co 2 was emitted by the crater maar of nyos cameroon it killed more than 1700 people and all animal life as far as 14 km away two hypotheses have been put forward to account for this disaster the chronologically first one imputes it to have been a phreatic eruption exceptionally co 2 rich as had been the case in february 1979 on the dieng plateau in central java indonesia where the erupting crater was lake less the second one claims a limnic origin for the co 2 release through an overturn of the 220 m deep lake nyos the hypolimnium of which was supposed to be oversaturated by dissolved gas of volcanic origin the present paper points to six observed facts for which the eruptive hypothesis easily accounts and which the authors of the limnic one do ignore

palaeomagnetic evolution of the cankiri basin central anatolia turkey implications for oroclinal bending due to indentation p alaeomagnetic data in combination with palaeostress data and anisotropy of magnetic susceptibility orientations are utilized to develop a tectonic evolutionary model for the early tertiary part of the omega shaped ca nkiri basin turkey the results reveal clockwise rotations in the northeast and anticlockwise rotations in the west and southeastern corner of the basin the magnetic inclinations indicate a northward drift of the ca nkiri basin and support an indentation model for the kirsehir block it is proposed that the shape of the cankiri basin was the result of indentation of the kirsehir block into the sakarya continent during northwards migration accompanying closure of neotethys it appears that the indentation started prior to eocene and ended before middle miocene times

new evidence and model on the evolution of the southeast anatolian orogen this paper describes the orogenic evolution of the southeast anatolian orogenic belt based mostly on new geologic data collected from its constituent tectonic units in the course of new mapping programs of the past decade the southeast anatolian orogenic segment of the alpides may be divided into three approximately east west trending zones from south to north they are the arabian platform followed by a zone of imbrication and then a zone of nappes the arabian platform includes a mostly marine sedimentary succession deposited from early cambrian to middle miocene time the zone of imbrication is a narrow belt sandwiched between the arabian platform and the zone of nappes it consists of imbricated thrust slices emplaced onto a late cretaceous to early miocene sequence the zone of nappes is the highest tectonic unit consisting of two stacks of nappes simply designated the lower and upper nappes the lower nappe is represented by the slices of a polyphase metamorpbic ophiolitic assemblage and the maden group the upper nappe rests on the lower nappe and is represented by the bitlis and poturge metamorphic massifs southeastern anatolia underwent two major episodes of alpide deformation the first occurred during the late cretaceous period when ophiolite was emplaced on the arabian platform this event was not the consequence of a continental collision the ophiolite obduction onto the arabian platform was followed by a regionwide extension and a new marine transgression over the platform immediately after the ophiolite obduction the second episode of deformation occurred during middle eocene miocene time in two distinct stages as a result of the progressive elimination and complete closure of the ocean s which led to the collision between the zone of nappes located to the north being a part of eurasia and the arabian plate the maden marginal basin formed north of the subduction zone that eliminated the ocean between eurasia and arabia along the southern margin of the taurus belt and abutted the arabian plate much later during the final collision the second episode of deformation formed the present orogenic segment leading to the amalgamation of different tectonic units these amalgamated nappes collided with the arabian plate and welded onto it at the latest stage of the orogenic evolution during the miocene epoch

the origin of neogene tectonic rotations in the galatean volcanic massif central anatolia a paleomagnetic study was carried out on neogene volcanic rocks at 30 sites within the galatean massif 40 4 n 31 5 e to determine possible block rotations due to stress variations two phases of rotation could be characterized as the result of neogene volcanic activity we suggest that the first stage of rotation was isolated in early middle miocene calc alkali rocks with a relative counterclockwise rotation of r r 20 2 9 3 with respect to eurasia this accommodates the south westward rotational collapse of the western anatolia peninsula across a pole on the bitlis suture in the neotectonic period on other hand a relative clockwise rotation of r r 27 3 6 4 with respect to eurasia is predicted in contrast to the uniform clockwise rotations extremely large clockwise rotations up to 264 are restricted in a narrow zone between two dextral faults we believe that the second stage rotations support the idea of individual microblock rotations due to deformation along the north anatolian fault zone

resonance in the gas discharge of the bocca nuova etna italy 1968 1969 abstract during 1968 1969 the bocca nuova a small vent 7 m across located in the northern part of mt etna s summit crater showed a resonating pipe phenomenon triggered by explosions at its bottom the emitted gases were mixed with air temperatures velocities dynamic pressures and co2 and n2 contents were recorded

neotectonic deformation in the eurasia arabia collision zone the east anatolian plateau e turkey evidence from palaeomagnetic study of neogene quaternary volcanic rocks palaeomagnetic studies of the neogene quaternary rocks of anatolia have been mostly interpreted in the light of its westward escape as a result of the collision between the arabian and eurasian plates along the bitlis zagros suture during the neotectonic period however within the collision zone in east anatolia palaeomagnetic data are not available in order to help understand the deformational history of eastern anatolia during the neotectonic period we have carried out a palaeomagnetic study of miocene quaternary volcanic rocks from 100 sites selected on the basis of their geographical position and known age the results indicate that the study area can be divided into five principal tectonic blocks based on earthquake activity and the rotation that the blocks underwent these blocks are the van block vb the kars block kb the anatolian block ab the pontide block pb and the arabian block arb the largest counterclockwise ccw tectonic rotations were encountered in the ab and pb whereas the largest clockwise cw rotations were recorded in the vb the sinistral east anatolian fault and the erzurum fault zone form the present boundary of these two contrasting cw and ccw rotating domains both the ab and the pb exhibit similar amount of rotation until the quaternary during which the ab rotated 13 ccw while the pb remained stable the quaternary rotation of the ab is attributed to the activity of the north anatolian fault the kb shows the smallest amount of cw rotation during all of the time intervals studied all of the blocks studied indicate an acceleration in the amount of rotations during the quaternary which was preceded by a period of relative tectonic stability during the late pliocene following the collision of the arabian plate with the eurasian plate during the mid miocene the crust was initially thickened by thrusting and folding this was followed by lateral extrusion and differential rotation of the crustal blocks during late miocene pliocene in response to ongoing indentation of the arabian plate our data show that strike slip faults that commonly separate wedge shape crustal blocks are the most significant means of accommodating the tectonic escape and rotation of crustal blocks in east anatolia delamination of the lower crust and the lithospheric mantle may have contributed to the deformation by thermally weakening the crust

les debits de co2 et de so2 volcaniques dans l atmosphere la contribution des volcans a l atmosphere est reevaluee a 5 107 tonnes de so2 et 108 tonnes de co2 par an

palaeomagnetic study of tertiary volcanic domains in southern turkey and neogene anticlockwise rotation of the arabian plate abstract following collision with eurasia the arabian shield indenter has continued to deform into the weak anatolian collisional collage that resulted from subduction of the neotethyan ocean differential movements have involved rotation and continuing northwards translation and have been accommodated mainly by slip along major transforms including the northward extension of the dead sea fault zone dsfz and the east anatolian fault zone eafz to aid in evaluating post collisional motions the palaeomagnetism of extensive volcanic domains at the northern margin of the stable shield in southern turkey is reported here together with the timing of emplacement as constrained by k ar study the age dating results indicate that volcanic activity occurred mainly during mid late miocene times corresponding to the final stages of suturing volcanic fields in the east of the investigated region are younger and correspond to neotectonic volcanism in brunhes and matuyama chrons thermal and alternating field demagnetization of 399 cores from 83 sites in basaltic lavas identifies 29 units of normal and 43 of reversed polarity with 11 sites having transitional or random directions volcanic fields west of the euphrates kilis gaziantep region with ages in the range 7 0 20 3 ma average 14 9 ma sd 4 3 ma have mean remanence d i 353 52 38 sites 5 3 lava fields east of the euphrates urfa region are dated 10 4 12 1 ma and yield a comparable mean remanence d i 350 50 17 sites 6 0 these collections are shown to have properly recorded palaeosecular variation with only minimal inclination shallowing and inferred anticlockwise rotations with respect to eurasia since mid miocene times are 10 9 4 3 and 14 0 5 0 respectively these contrast with clockwise rotation of 6 3 4 3 derived from late matuyama brunhes epoch volcanic rocks immediately to the north west of the arabian margin where rotational impingement of the shield indenter into fault blocks within the karasu rift at the northern extension of the dsfz interacts with left lateral motion at a rate of 0 5 cm year along this zone to produce small scale vertical axis rotations results from the volcanic suites sited on the stable shield are compared with other results from the arabian plate to conclude that it did not rotate significantly following closure of the bitlis suture until late miocene early pliocene times since when it has rotated anticlockwise at a rate of 1 0 myr this is comparable to the present day rate of rotation deduced from gps and correlates with crustal separation and sea floor spreading in the red sea it also temporally links the rotation of the arabian plate to the initiation of the intracontinental transforms north and east anatolian fault zones within anatolia and to the subsequent extrusion of blocks within this accretionary domain by tectonic escape to the west

neogene anticlockwise rotation of central anatolia turkey preliminary palaeomagnetic and geochronological results abstract a palaeomagnetic and geochronological study was carried out on fifty sites from the neogene volcanic province of central anatolia results from this analysis show that there has been a progressive anticlockwise rotation of this region over the period spanning at least the last 10 12 ma we interpret this rotation as having resulted from the collision of arabia with anatolia along the bitlis suture if we assume a constant rate of rotation we obtain a rate of 2 4 ma this value is significantly higher than the present day rotation rate obtained from gps 1 3 0 1 ma and also implies that these rocks have been rotating at their present rate since well before collision occurred along the bitlis suture 12 ma a geologically unreasonable conclusion if however we combine these data with data from other palaeomagnetic studies with good age control the resultant curve seems to show three distinct linear segments 1 0 5 ma with a very slow rate of rotation 1 2 ma 2 5 12 ma where we observe a rapid increase of rotation rate to 6 5 ma and 3 12 ma when the rotation rate is again essentially zero 0 041 ma these results are generally consistent with a model calling for middle miocene collision along the bitlis suture and late plio pleistocene initiation of motion along the north and east anatolian fault zones

first paleomagnetic evidence for a post eocene clockwise rotation of the western taurides thrust belt east of the isparta reentrant southwestern turkey abstract a paleomagnetic study was carried out on 23 sites sampled in paleocene eocene and lower miocene sedimentary formations of the western taurides belt east of the isparta reentrant the paleomagnetic data based on twelve suitable sites record a coherent post eocene 40 clockwise rotation throughout the area studied we interpret this regional rotation as a semi rigid rotation of the whole western taurides belt above a major deep decollement level together with previously published data these new results suggest that the isparta reentrant would result from diachronous opposite rotations of the two branches first a late eocene oligocene clockwise rotation of the akseki beysehir taurides initiating the tauride arc and then anticlockwise rotation of the lycian taurides probably during middle miocene times

recent global sea level acceleration started over 200 years ago 1 we present a reconstruction of global sea level gsl since 1700 calculated from tide gauge records and analyse the evolution of global sea level acceleration during the past 300 years we provide observational evidence that sea level acceleration up to the present has been about 0 01 mm yr2 and appears to have started at the end of the 18th century sea level rose by 6 cm during the 19th century and 19 cm in the 20th century superimposed on the long term acceleration are quasi periodic fluctuations with a period of about 60 years if the conditions that established the acceleration continue then sea level will rise 34 cm over the 21st century long time constants in oceanic heat content and increased ice sheet melting imply that the latest intergovernmental panel on climate change ipcc estimates of sea level are probably too low

crustal deformation and kinematics of the eastern part of the north anatolian fault zone turkey from gps measurements abstract the north anatolian fault zone nafz is a 1200 km long dextral strike slip fault zone forming the boundary between the eurasian and anatolian plates it extends from the gulf of saros north aegean in the west to the town of karliova in eastern turkey although there have been numerous geodetic studies concerning the crustal deformation velocity field and the slip rate of the nafz along its western and central segments geodetic observations along the eastern section of the nafz are sparse in order to investigate the gps velocities and the slip rate along the eastern part of the nafz a dense gps network consisting of 36 benchmarks was installed between tokat and erzincan on both sides of the fault zone and measured from 2006 to 2008 measurement results indicate that the slip rate of the nafz increases westwards within about 400 km from 16 3 2 3 mm year to 24 0 2 9 mm year in consistence with the observation that the anatolian block is being pulled by the hellenic trench rather than being pushed by the arabian plate as a result of continental collision between the arabian and eurasian plates in eastern turkey since late miocene modelling the gps velocities shows that fault locking depth increases also in the same direction from 8 1 3 3 km to 12 8 3 9 km slip rate decreases as moving off the hellenic trench an average slip rate of 20 1 2 4 mm year and a locking depth of 12 5 3 5 km are also estimated for the entire study area by using all of the gps measurements obtained in this study the gps velocities are in good agreement with the kinematic models created by paleomagnetic studies in the region and complete the overall picture

sn attenuation in the anatolian and iranian plateau and surrounding regions an edited version of this paper was published in geophysical research letters by the american geophysical union agu copyright 2003 agu see also http www agu org pubs crossref 2003 2003gl018020 shtml http atlas geo cornell edu turkey publications gok et al 2003 htm

tomographic imaging of lg and sn propagation in the middle east observations based on relatively limited data recorded by sparsely distributed stations have indicated that regional seismic phase propagation lg and sn is very complex in the middle east accurate characterization of regional seismic wave propagation in this region necessitates the use of a large number of seismic stations we have compiled a large data set of regional and local seismograms recorded in the middle east this data set comprises approximately four years of data from national short period networks in turkey and syria data from temporary broadband arrays in saudi arabia and the caspian sea region and data from gsn mednet and geofon stations in the middle east we have used this data set to decipher the character and pattern of regional seismic wave propagation we have mapped zones of blockage as well as inefficient and efficient propagation for lg pg and sn throughout the middle east two tomographic techniques have been developed in order to objectively determine regions of lithospheric attenuation in the middle east we observe evidence of major increase in lg attenuation relative to pg across the bitlis suture and the zagros fold and thrust belt corresponding to the boundary between the arabian and eurasian plates we also observe a zone of inefficient sn propagation along the dead sea fault system which coincides with low pn velocities along most of the dead sea fault system and with previous observations of poor sn propagation in western jordan our observations indicate that in the northern portion of the arabian plate south of the bitlis suture there is also a zone of inefficient sn propagation that would not have been predicted from prior measurements of relatively low pn velocities mapped high attenuation of sn correlates well with regions of cenozoic and holocene basaltic volcanism these regions of uppermost mantle shear wave attenuation most probably have anomously hot and possibly thin lithosphere

pn tomographic imaging of mantle lid velocity and anisotropy at the junction of the arabian eurasian and african plates an edited version of this paper was published by blackwell publishing in geophysical journal international copyright 2004 blackwell publishing see also http www blackwell synergy com doi abs 10 1111 j 1365 246x 2004 02355 x http atlas geo cornell edu middleeastnorthafrica publications al lazki2004 htm

a 20th century acceleration in global sea level rise 1 multi century sea level records and climate models indicate an acceleration of sea level rise but no 20th century acceleration has previously been detected a reconstruction of global sea level using tide gauge data from 1950 to 2000 indicates a larger rate of rise after 1993 and other periods of rapid sea level rise but no significant acceleration over this period here we extend the reconstruction of global mean sea level back to 1870 and find a sea level rise from january 1870 to december 2004 of 195 mm a 20th century rate of sea level rise of 1 7 0 3 mm yr 1 and a significant acceleration of sea level rise of 0 013 0 006 mm yr 2 this acceleration is an important confirmation of climate change simulations which show an acceleration not previously observed if this acceleration remained constant then the 1990 to 2100 rise would range from 280 to 340 mm consistent with projections in the ipcc tar

long term elasticity in the continental lithosphere modelling the aden ridge propagation and the anatolian extrusion process summary the evolution of the gulf of aden and the anatolian fault systems are modelled using the principles of elastic fracture mechanics usually applied to smaller scale cracks or faults the lithosphere is treated as a plate and simple boundary conditions are applied that correspond to the known plate boundary geometry and slip vectors the models provide a simple explanation for many observed geological features for the gulf of aden the model predicts why the ridge propagated from east to west from the owen fracture zone towards the afar and the overall form of its path the smaller en echelon offsets can be explained by upward propagation from the initially created mantle dyke while the larger ones may be attributed to the propagating rupture interacting with pre existing structures for anatolia the modelling suggests that the east anatolian fault was created before the north anatolian fault could form once both faults were formed however activity could switch between them the time scales over which this should take place are not known but evidence for switching can be found in the historical seismicity for aden and anatolia pre existing structures or inhomogeneous stress fields left from earlier orogenic events have modified the processes of propagation and without an understanding of the existence of such features the propagation processes cannot be fully understood furthermore a propagating fault can extend into an active region where it would not have initiated the north anatolian fault encountered slow but active extension when it entered the aegean about 5 ma and the stress field associated with the extending fault has progressively modified aegean extension in the central aegean activity has been reduced while to the north west on features such as the gulfs of evvia and corinth activity has been increased the field observation that major structures propagate and the success of simple elastic models suggest that the continental crust behaves in an elastic brittle or elastic plastic fashion even though laboratory tests may be interpreted to suggest viscous behaviour there are major problems in scaling from the behaviour of small homogeneous samples to the large heterogeneous mantle and large scale observations should be treated more seriously than extrapolations of the behaviour of laboratory experiments over many orders of magnitude in space and time the retention of long term elasticity and localised failure suggests a similar gross rheology for the oceanic and continental lithospheres even though it is incorrect to attribute differences in behaviour to the former being rigid i e elastic and the latter viscous oceanic and continental lithosphere behave in different ways unlike oceanic crust continental crust is buoyant and cannot be simply created or destroyed the process of thickening or thinning works against gravity preventing large displacements on extensional or contractional features in the upper mantle the equivalents of ridge or subduction systems are suppressed before they can accommodate large displacements and activity must shift elsewhere on the other hand strike slip boundaries and extrusion processes are favoured

palaeomagnetic study of the karacadag volcanic complex se turkey monitoring neogene anticlockwise rotation of the arabian plate abstract the karacadag volcanic centre in south east turkey is a major basaltic complex sited at the northern margin of the arabian plate and emplaced in several pulses between 11 ma and late quaternary times we have sampled 71 sites in lavas of this complex to constrain the palaeomagnetic record and hence the chronology of magmatic activity and regional rotation palaeomagnetic study at sixty two sites yields significant component definition with mixed normal and reversed polarities from age dating and morphologic criteria we identify three major episodes of lava emplacement and site mean directions of magnetisation for these divisions resolve migration of the palaeofield direction for the northern sector of the arabian plate since mid miocene times successive reversed polarity group mean directions are d i 175 50 5 n 37 r 33 13 95 4 1 for the oldest siverek division mean age estimate 11 1 6 7 ma d i 173 4 46 0 n 16 r 15 67 95 5 5 for the middle karacadag division mean age 3 3 ma and d i 167 7 47 6 n 6 r 5 93 95 7 9 for the youngest ovabag division 1 9 ma present the first two results merit a tectonic interpretation and consistent anticlockwise rotation of 9 is recognised in the karacadag volcanic centre between 11 and 3 3 ma the mean directions conform to palaeomagnetic results from other undeformed neogene igneous complexes of comparable age range further to the west along the northern perimeter of the arabian plate the amount of tectonic rotation observed in late pliocene and older volcanic units from this plate is found to be statistically constant tectonism responsible for rotation therefore appears to have been temporally confined to the last 2 myr which is long after collision with the anatolides and closure of the bitlis suture this conclusion conforms to the young distributed block rotations recognised in the anatolides and aegean and correlates with the regime of tectonic escape of terranes to the west

are there biomedical criteria to assess an acute carbon dioxide intoxication by a volcanic emission abstract on august 21 1987 more than 1800 people thousands of head of cattle and countless wild animals including birds were killed by a gas release which occurred during about 4 hours at the lake in the crater iwi at nyos in cameroon plant life was mostly unaffected an international inquiry was performed by british french italian japanese and u s volcanologists and physicians to determine what had been the cause of this disaster an international conference organised by united nations educational scientific and cultural organisation u n e s c o the cameroon government and the u n economic commission for africa held in yaounde march 1987 concluded that the cause of sudden death was suffocation asphyxia in a carbon dioxide atmosphere the medical findings have been explained by asphyxia caused by carbon dioxide the presence of other volcanic gases e g hydrogen sulfide cannot be ruled out sigvaldason 1989 this issue this paper reviews what is mainly known about an acute carbon dioxide intoxication in order to disprove or confirm the diagnosis and helps to interpret the field observations and testimonies to provide a basis to discuss the prevention of such an intoxication

east anatolian high plateau as a mantle supported north south shortened domal structure an edited version of this paper was published by the american geophysical union agu copyright 2003 agu see also http www agu org pubs crossref 2003 2003gl017858 shtml http atlas geo cornell edu turkey publications sengor et al 2003 htm

neotectonic deformation linking the east anatolian and karatas osmaniye intracontinental transform fault zones in the gulf of iskenderun southern turkey deduced from paleomagnetic study of the ceyhan osmaniye volcanics 1 left lateral strike slip along the dead sea fault zone dsfz between the african and arabian plates is partitioned into a complex set of motions at its northern extension where arabia impinges into the anatolian collage as a result the nature of the contemporary link between the east anatolian and dead sea transforms is unclear to quantify strike slip motion expressed as tectonic rotations along the inferred southwest continuation of the east anatolian fault zone eafz we have investigated the paleomagnetism of young 1 ma volcanics in the adana basin gulf of iskenderun region comprising the ceyhan osmaniye volcanic suite this volcanism is sited close to the intersection between the sinistral karatas osmaniye fault zone kofz and the neotethyian suture nine sites from a basaltic lava field in the vicinity of osmaniye are entirely of normal polarity and in the context of their very young morphologies are assigned to the brunhes chron declinations are mostly clockwise from the present field this age assignment identifies rapid recent 780 ka uplift at the head of the gulf of iskenderun and is linked to a diversion of the ceyhan river drainage and ongoing regional tilting eight sites yield a mean declination of 11 3 10 implying clockwise block rotation on riedel type fractures on the northwest side of the kofz seven lavas sites from a volcanic succession near botas at the southwestern extension of the volcanic lineament are of reversed polarity and rotated counterclockwise by 43 7 with respect to the present field polarity k ar and morphological evidence indicate an assignment toward the latter part of the matuyama chron and identify rapid neogene block rotation of a flake within the kofz an inferred maximum slip rate of 0 6 cm year on this fault zone is comparable with lower estimates of slip on the eafz and suggests that most strike slip on the dsfz is now being partitioned to the west of the gulf of iskenderun on a developing strike slip zone linking with the cyprus arc

a palaeomagnetic study of the sivas basin central turkey crustal deformation during lateral extrusion of the anatolian block abstract the sivas basin is a complex collage of eocene and younger rocks located within the wedge shaped eastern margin of the anatolian block between the dextral north anatolian fault zone and the sinistral eastern anatolian fault zone it has been subject to ongoing deformation by movement of the arabian block into eurasia and concomittant sideways expulsion of the anatolian block post collisional deformation since mid miocene times has been dominated by n s to nw se compression expressed by thrusting and strike slip faulting cretaceous and eocene rocks were magnetically overprinted to variable degrees during the collisional phase although these overprints have since been rotated mostly anticlockwise rocks emplaced during the neotectonic history are high fidelity palaeomagnetic recorders of subsequent block movements regional anticlockwise rotation is recognised across the basin with differential rotation of fault and thrust bounded blocks an absence of perceptible differences between group mean rotations identified from miocene pliocene and quaternary units shows that most regional rotation has been concentrated within the latest phase of the neotectonic history during quaternary times at an average rate of 10 ma commencement of this rotation postdates initiation of the north anatolian fault zone implying that compression following collision was accomodated initially by crustal thickening during late miocene and pliocene times subsequent anticlockwise rotations have resulted from sideways expulsion of blocks to the south of the central anatolian thrust along major ne sw sinistral faults to achieve the crustal shortening resulting from n s compression these fault orientations and their sense of motion are explained by a prandtl model involving deformation of a triangular plastic terrane the anatolian block between two rigid plates eurasia and afro arabia the variations in regional rotation identified by palaeomagnetism show that average contemporary anticlockwise rotation of anatolia revealed by gps data 1 2 ma is achieved by variable and locally large block rotations between major thrusts and strike slip faults

differential neotectonic rotations in anatolia and the tauride arc palaeomagnetic investigation of the erenlerdaǧ volcanic complex and isparta volcanic district south central turkey abstract in the anatolian sector of the alpine himalayan collisional belt a palaeotectonic phase of terrane accretion has been succeeded by a neotectonic phase of intracontinental deformation as the afro arabian plate has continued to impinge differentially into the accreted collage the resulting tectonic escape has during the last few million years extruded and rotated blocks in a southwesterly direction this paper reports a palaeomagnetic investigation of the erenlerda volcanic complex and isparta alkaline volcanic district undertaken to extend analysis of crustal rotation into the southwestern part of the anatolian region and investigate the interaction with the isparta angle and the extensional province of western turkey the erenlerda volcanism comprises three phases of volcanism the oldest sille volcanics 11 7 11 4 ma yield a mean d 150 i 52 rotated anticlockwise during early stages of crustal thickening and deformation before a later miocene episode c 10 9 8 9 ma d 183 i 47 and a mio pliocene episode d 179 i 51 the latter two episodes indicate that no significant rotation has resulted during the neotectonic crustal extrusion in this southwestern sector of anatolia further to the west within the isparta angle a 4 7 4 0 ma alkaline episode yields a mean of d 186 i 53 rotated slightly clockwise the pattern of palaeomagnetic declinations across anatolia shows rotations that are strongly anticlockwise in the east near the arabian pincer and diminish towards the west to become zero or slightly clockwise at the western extremity of the collage the timing of rotation also appears to become younger towards the south crustal deformation has therefore been distributed and the net effect of terrane extrusion to the west and south has been to expand the curvature of the tauride arc and by inference the cyprian arc where good age control exists in cappadocia and the sivas basin rotations are found to be concentrated within the last few million years and are up to an order higher than rates deduced from global positioning system the palaeomagnetic data imply that the neotectonic deformation following collision initially produced crustal thickening resulting in uplift of the anatolian plateau and was only subsequently accommodated by major differential block rotation during tectonic escape

palaeomagnetic study of the erciyes sector of the ecemis fault zone neotectonic deformation in the southeastern part of the anatolian block

neotectonic deformation in the transition zone between the dead sea transform and the east anatolian fault zone southern turkey a palaeomagnetic study of the karasu rift volcanism in southern turkey ongoing differential impingement of arabia into the weak anatolian collisional collage resulting from subduction of the neotethyan ocean has produced one of the most complex crustal interactions along the alpine himalayan orogen several major transforms with disputed motions including the northward extension of the dead sea fault zone dsfz meet in this region to evaluate neotectonic motion on the amanos and east hatay fault zones considered to be northward extensions of the dsfz the palaeomagnetism of volcanic fields in the karasu rift between these faults has been studied remanence carriers are low ti magnetites and all except 5 of 51 basalt lavas have normal polarity morphological polarity and k ar evidence show that rift formation occurred largely during the brunhes chron with volcanism concentrated at 0 66 0 35 ma and a subsidiary episode at 0 25 0 05 forty four units of normal polarity yield a mean of d i 8 8 54 7 with inclination identical to the present day field and declination rotated clockwise by 8 8 4 0 within the 15 km wide hassa sector of the karasu rift the volcanic activity is concentrated between the amanos and east hatay faults both with left lateral motions which have rotated blocks bounded by nw se cross faults in a clockwise sense as the arabian block has moved northwestwards an average lava age of 0 5 ma yields a minimum cumulative slip rate on the system bounding faults of 0 46 cm year according with the rate deduced from the africa arabia euler vector and reduced rates of slip on the southern extension of the dsfz during plio quaternary times estimates deduced from offsets of dated lavas flows and morphological features on the amanos fault zone tectonophysics 344 2002 207 are lower 0 09 0 18 cm year probably because they are limited to surface fault breaks and do not embrace the seismogenic crust results of this study suggest that most strike slip on the dsfz is taken up by the amanos east hatay afrin fault array in southern turkey comparable estimates of quaternary slip rate are identified on other faults meeting at an unstable fff junction dsfz east anatolian fault zone karatas fault zone a deceleration in slip rate across the dsfz and its northward continuation during plio quaternary times correlates with reorganization of the tectonic regime during the last 1 3 ma including tectonic escape within anatolia establishment of the north and east anatolian fault zones bounding the anatolian collage in mid late pliocene times a contemporaneous transition from transpression to transtension and concentration of all basaltic magmatism in this region within the last 1 ma

surface waveform tomography of the turkish iranian plateau summary the middle east is a tectonically complex region consisting of terrains as diverse as precam brian shields and young orogens the dominant tectonic feature is the turkish iranian plateau a recently elevated seismically active region along the zagros bitlis suture which results from the collision of the arabian plate with eurasia in this study we use surface waveform tomography to elucidate the upper mantle shear wave velocity structure beneath the turkish iranian plateau and adjacent regions the main large scale feature in the tomographic model is a low shear wave velocity anomaly in the uppermost mantle beneath the plateau this low velocity feature correlates with a long wavelength free air gravity anomaly and with recent volcanism whose geochemistry has a lower lithospheric mantle signature seismology gravity and volcanism all suggest the presence of a thin lithosphere and warm upper mantle beneath the turkish iranian plateau the upper mantle low shear wave velocity zone the high free air gravity and the deep lithospheric source depth for the basaltic volcanism are all consistent with a partial delamination of the lithosphere as a result of earlier lithospheric thickening resulting from the continental collision

lithospheric structure of the arabian and eurasian collision zone in eastern turkey from s wave receiver functions summary crustal and upper mantle seismic discontinuities beneath eastern turkey are imaged using teleseismic s to p converted phases three crustal phases are observed the moho with depth ranging between 30 and 55 km indicating variable tectonic regimes within this continental collision zone an upper crustal discontinuity at approximately 10 km depth and various crustal low velocity zones possibly associated with recent quaternary volcanism imaging of the upper mantle is complicated by the 3 d geometry of the region in particular due to the bitlis zagros suture zone however several upper mantle s to p converted phase are identified as being the signature of the lithosphere asthenosphere boundary lab the inferred lab for the eastern anatolian accretionary complex indicates that eastern turkey has an anomalously thin between 60 and 80 km lithosphere which is consistent with an oceanic slab detachment model the observed lab phases for the arabian shield and iranian plateau indicate that lithospheric thickness for these stable regions is on the order of 100 to 125 km thick which is typical of continental margins

counterclockwise rotation of the anatolian block abstract seismological and other data from the boundaries of anatolia are used to discuss the motion and plate tectonics of this block models which include a rotation of anatolia around a single pole are shown to be inconsistent with much of this data in particular a westward motion of anatolia which is the most commonly used model should be reconsidered models which use a single pole of rotation fail because they assume the north anatolian fault to be an ideal transform fault which describes all of the motion between anatolia and the black sea in effect internal deformation in the form of extension in western anatolia and for the most part strike slip faulting in eastern anatolia are important and account for some of the relative motion thus a more appropriate model for this region is one which not only stresses the dominance of the north anatolian fault but also recognises the importance of internal deformation and the limitation of classic plate tectonic models which this deformation implies the preferred model for the motion of anatolia is a nonuniform tight counterclockwise rotation approximated by the shape of the north anatolian fault as well as by the faults which splay from it to the south such a model is consistent with data from the boundaries of anatolia including the source mechanism of earthquakes and depth of benioff zone along the southern boundary of the block counterclockwise rotation of anatolia is the natural consequence of the collision of arabia with eastern anatolia coupled with subduction in the eastern mediterranean

an up to date crustal deformation map of iran using integrated campaign mode and permanent gps velocities we present the most extensive and up to date unified gps velocity field for iran we processed the data collected during 10 yr 2006 2015 from the iranian permanent gnss network ipgn and combined them with previously published velocity solutions from the gps survey measurements during 1997 2013 we analysed this velocity field using a continuum approach to compute a new strain rate map for this region and we designed a block model based on the main geological morphological and seismic structures comparison between both approaches suggests similar results and allows us to present the first comprehensive first order fault slip rate estimates for the whole of iran our results confirm most of the results from previous geodetic studies however we also show a trade off between the coupling ratio of the iranian makran subduction interface and the kinematics of the faults north of the makran in the jazmurian depression indeed although too scarce to accurately estimate a coupling ratio we show that coupling higher than 0 4 on the plate interface down to a depth of 25 km will induce extension on the e w faults in the jazmurian region however the sites close to the shoreline suggest a low coupling ratio hence the coupling on this plate interface is probably more complicated than previously described and the iranian makran subduction interface mechanical behaviour might be similar to that on the hellenic subduction zone

genesis of collision volcanism in eastern anatolia turkey late cenozoic volcanism in eastern anatolia extends in a broad sw ne trending belt across the arabia eurasia collision zone from the arabian foreland basin in the southwest and to the kars plateau and lesser caucasus in the northeast foreland volcanism is dominated by basaltic shield and fissure eruptions of transitional tholeiitic alkaline composition volcanism on the thickened crust north of the bitlis thrust zone varies from the mildly alkaline volcano nemrut and older mus volcanics in the south through the transitional calc alkaline alkaline volcanoes bingol and suphan and the alkaline volcano tendurek to the calc alkaline volcano ararat and older kars plateau volcanics in the north isotope sr nd and trace element systematics indicate that the lavas from the foreland were derived from the mantle lithosphere of the arabian continent which had been enriched by small volumes of asthenospheric melts over a period of time and that lavas from the alkaline volcanic area around mus and the volcanoes nemrut and tendurek north of the bitlis thrust zone were derived from a lithospheric source of similar composition either from the same underthrust arabian continent or from the bitlis massif microcontinent by contrast the transitional lavas from bingol and suphan and the calc alkaline lavas from ararat and kars were derived from lithosphere carrying a distinct subduction signature inherited from pre collision subduction events positive correlations between 87sr 86sr and sio2 and rb nb and sio2 in the alkaline and transitional lavas suggest that combined assimilation and fractional crystallization was an important process within at least part of the thickened crust of the collision zone trace element covariation diagrams such as y rb indicate the importance of hornblende crystallization at depth and orthopyroxene at shallow levels within the calc alkaline provinces in contrast to the consistently anhydrous crystallization sequences of the alkaline lavas trace element diagrams based on the covariation of compatible and incompatible elements point to moderate low degrees of partial melting with residual clinopyroxene throughout and residual garnet in the foreland province consideration of mineral stabilities mantle solidi and geothermal gradients before and after collision suggest that lithospheric thickening should both increase the thickness of metasomatized lithosphere and depress the metasomatized zone to greater depths probably beneath the amphibole and dolomite breakdown curves perturbation of the thickened lithosphere by delamination of the thermal boundary layer perhaps coupled with local stretching associated with pull apart basins on strike slip fault systems is then sufficient to generate melt the composition of that melt being largely dependent on the enrichment history of the lithosphere in question in eastern anatolia volcanism appears to have started between about 8 and 6 ma ago some 5 ma after the start of rapid uplift of the east anatolian plateau

global positioning system constraints on plate kinematics and dynamics in the eastern mediterranean and caucasus we present and interpret global positioning system gps measurements of crustal motions for the period 1988 1997 at 189 sites extending east west from the caucasus mountains to the adriatic sea and north south from the southern edge of the eurasian plate to the northern edge of the african plate sites on the northern arabian platform move 18 2 mm yr at n25 5 w relative to eurasia less than the nuvel 1a circuit closure rate 25 1 mm yr at n21 7 w preliminary motion estimates 1994 1997 for stations located in egypt on the northeastern part of africa show northward motion at 5 6 2 mm yr also slower than nuvel ia estimates 10 1 mm yr at n2 4 e eastern turkey is characterized by distributed deformation while central turkey is characterized by coherent plate motion internal deformation of 2 mm yr involving westward displacement and counterclockwise rotation of the anatolian plate the anatolian plate is de coupled from eurasia along the right lateral strike slip north anatolian fault naf we derive a best fitting euler vector for anatolia eurasia motion of 30 7 0 8 n 32 6 0 4 e 1 2 0 1 myr the euler vector gives an upper bound for naf slip rate of 24 1 mm yr we determine a preliminary gps arabia anatolia euler vector of 32 9 1 2 n 40 3 1 1 e 0 8 0 2 myr and an upper bound on left lateral slip on the east anatolian fault eaf of 9 1 mm yr the central and southern aegean is characterized by coherent motion internal deformation of 2 mm yr toward the sw at 30 1 mm yr relative to eurasia stations in the se aegean deviate significantly from the overall motion of the southern aegean showing increasing velocities toward the trench and reaching 10 1 mm yr relative to the southern aegean as a whole

palaeomagnetically defined rotations of fault bounded continental blocks in the north anatolian shear zone north central anatolia abstract the 1200 km long north anatolian transform fault connects the east anatolian post collisional compressional regime in the east with the aegean back arc extensional regime to the west this active dextral fault system lies within a shear zone reaching up to 100 km in width and consists of southward splining branches these branches which have less frequent and smaller magnitude earthquake activity compare to the major transform cut and divide the shear zone into fault delimited blocks comparison of palaeomagnetic data from 46 sites in the eocene volcanics from different blocks indicate that each fault bounded block has been affected by vertical block rotations although clockwise rotations are dominant as expected from dextral fault bounded blocks anticlockwise rotations have also been documented these anticlockwise rotations are interpreted as due to anticlockwise rotation of the anatolian block as indicated by gps measurements and the effects of unmapped faults or pre north anatolian fault tectonic events

regional interdecadal variability in bias corrected ocean temperature data abstract regional interdecadal variability on subbasin to basin scales is shown to be a robust feature of the post world war ii wwii historical temperature record even after a recently proposed bias correction to xbt fall rates is applied this study shows that the previously reported strong regional variability is generally unaffected by this correction even though the interdecadal variability in the most recently published estimates of global ocean heat content is much reduced after a correction is applied following methods used in previous trend analysis work estimates of interdecadal trends are calculated for individual regions of the global ocean where there are sufficient data spatial maps of temperature trends for the surface and three subsurface depths 50 100 and 300 m are presented with both bias corrected and uncorrected data trends at 100 and 300 m shown for comparison in the upper two depths and at the surface interdecadal variability is shown to be present and strong in most o

gps constraints on continental deformation in the africa arabia eurasia continental collision zone and implications for the dynamics of plate interactions 1 the gps derived velocity field 1988 2005 for the zone of interaction of the arabian african nubian somalian and eurasian plates indicates counterclockwise rotation of a broad area of the earth s surface including the arabian plate adjacent parts of the zagros and central iran turkey and the aegean peloponnesus relative to eurasia at rates in the range of 20 30 mm yr this relatively rapid motion occurs within the framework of the slow moving 5 mm yr relative motions eurasian nubian and somalian plates the circulatory pattern of motion increases in rate toward the hellenic trench system we develop an elastic block model to constrain present day plate motions relative euler vectors regional deformation within the interplate zone and slip rates for major faults substantial areas of continental lithosphere within the region of plate interaction show coherent motion with internal deformations below 1 2 mm yr including central and eastern anatolia turkey the southwestern aegean peloponnesus the lesser caucasus and central iran geodetic slip rates for major block bounding structures are mostly comparable to geologic rates estimated for the most recent geological period 3 5 myr we find that the convergence of arabia with eurasia is accommodated in large part by lateral transport within the interior part of the collision zone and lithospheric shortening along the caucasus and zagros mountain belts around the periphery of the collision zone in addition we find that the principal boundary between the westerly moving anatolian plate and arabia east anatolian fault is presently characterized by pure left lateral strike slip with no fault normal convergence this implies that extrusion is not presently inducing westward motion of anatolia on the basis of the observed kinematics we hypothesize that deformation in the africa arabia eurasia collision zone is driven in large part by rollback of the subducting african lithosphere beneath the hellenic and cyprus trenches aided by slab pull on the southeastern side of the subducting arabian plate along the makran subduction zone we further suggest that the separation of arabia from africa is a response to plate motions induced by active subduction

geomagnetic secular variation and the statistics of palaeomagnetic directions in this study we examine the role of palaeosecular variation psv in the use of statistics for palaeomagnetic studies and we provide new reliability criteria for palaeomagnetic poles or directions we first conclude that fisher statistics should not be applied to average palaeomagnetic directions but to virtual geomagnetic pole vgp distributions instead secondly we strongly advocate that typical properties of geomagnetic field behaviour are taken into account in the assessment of palaeomagnetic data sets the latitude dependent properties e s k provide useful guidelines for the reliability of a palaeomagnetic data set a reliable assessment of these properties depends on the sufficient number of palaeomagnetic samples being taken therefore as an additional instrument of assessing data sets we provide a n dependent a95 envelope bounded by an upper limit a95max and a lower limit a95min that helps to ascertain whether or not a distribution has sufficiently well sampled psv and therefore geomagnetic field behaviour applying these criteria is indispensable for studies of geomagnetic behaviour or for studies aiming at using tk03 gad for inclination error correction through the elongation inclination e i method for palaeomagnetic studies aimed at geological reconstructions they form helpful guidelines and increase the confidence in the rocks having faithfully recorded the field an analysis of published eastern mediterranean data shows that the vast majority of studies do not conform to the van der voo criteria in particular with respect to n and a95 we have provided criteria that are on the one hand more lenient lower n may still provide relevant information and on the other hand more strict for high n the criterion of a95 16 should be adapted to a requirement of lower a95 e g a95 80

an example of health hazard people killed by gas during a phreatic eruption dieng plateau java indonesia february 20th 1979 on february 20th 1979 142 inhabitants of dieng plateau indonesia were asphyxiated by poisonous gases during a mild phreatic eruption from later fields gas collection and analysis the casualties are considered to be due to co2 rich volcanic gases