paleomagnetic evidence for the miocene counter clockwise rotation of northeast japan rifting process of the japan arc paleomagnetic results have been obtained from more than 700 oriented samples in igneous rocks of cretaceous to miocene age from northeast japan the remanent magnetizations of welded tuffs with age between 32 ma and 21 ma old from 17 widely distributed sampling sites in northeast japan are fairly well grouped with a mean ofd 41 2 i 56 5 95 7 2 the remanent magnetization of welded tuffs of 14 ma and 11 ma from 4 sites shows a northerly direction d 11 7 i 60 5 95 15 3 these data imply that northeast japan was apparently subjected to a counter clockwise rotation through 47 14 about a vertical axis on the representative point of northeast japan 141 e 39 n during the past 21 ma comparing with the period of the clockwise rotation of southwest japan the differential rotation between northeast japan and southwest japan is concluded to have occurred concurrently during the period between 21 ma and 12 ma a rifting model of the japan arc is proposed northeast japan rotated counter clockwise through 50 about a northern pivot at 146 e 44 n while southwest japan rotated clockwise through 54 about a southern pivot at 129 e 34 n the differential rotation about different rotation pivots gives rise to the opening of a diamond shaped back arc basin the japan sea

sedimentation in pull apart basins active examples in eastern turkey the erzincan susehri niksar and lake hazar basins are actively evolving pull apart basins in eastern turkey their structural drainage and depositional systems generally support a pull apart basin sedimentation model based on ancient pull apart basin deposits this model involves marginal coarse grained sedimentation adjacent to master faults axial fine grained sedimentation away from master faults and high sedimentation rates however studies of the turkish pull apart basins suggest the following refinements in the model 1 detailed sedimentary facies patterns and the dominant facies of a pull apart basin vary according to basin shape climate drainage character and volcanic activity depositional environments near fault bounded margins include alluvial fan fan delta and alluvial apron depositional environments in central areas away from fault bounded margins include active braid plain inactive braid plain meander plain salt playa marsh lacustrine mouth bar delta and volcanic 2 i

neotectonics in the eastern north anatolian fault region turkey advocates crustal extension mapping from sar ers imagery and digital elevation model abstract this paper concerns the neotectonics of the eastern part of the anatolian block bounded respectively to the north and the east by the north anatolian naf and the east anatolian faults eaf meeting at karliova the study is based on imagery of synthetic aperture radar sar scenes acquired by the european remote sensing ers satellite and on views of a digital elevation model dem complemented with fault analysis in the field we show that extensional tectonics associated with transcurrent displacements prevail in the karliova triangle and beyond new local releasing bends or pull apart basins and push up structures along the naf have been demonstrated more importantly anatolia is composed of blocks less than 50 km in width that are tilted and move relative to each other they are compatible with a detachment within the crust of anatolia we argue that an escape wedge has migrated through time from west to east with successive jumps to form the present day karliova triangle at each stage the escape wedge was easterly bounded by a ne sw striking fault zone similar to the eaf in each escape wedge clockwise block rotations predate strike slip tectonics along the n110 e striking naf this is the case for instance for the erzincan basin where the first movements were parallel to the sw striking ovacik fault an early equivalent of the eaf and turned later to the west the detached crustal blocks moved southwestward then westward and extended at the same time in order to occupy the increasing surface within the successive escape wedges this is not the behaviour of simple lateral extrusion of the anatolian lithospheric block induced by forces applied at its boundaries by the adjacent plates but rather that of detached crustal blocks submitted to extension as a consequence of backward retreat of the hellenic slab and buoyancy forces arising from crustal thickness differences

control of reservoir geometry and stratigraphic trapping by erosion surface e5 in the pembina carrot creek area upper cretaceous cardium formation alberta canada 1 seven major erosion e surfaces are found within the 100 m thick cardium formation in the subsurface of alberta erosion surface e5 has up to 20 m of erosional relief in the carrot creek area and is cut into originally horizontal open marine sandstones and mudstones the e5 surface has been correlated into the pembina area by construction of a structure map based on 2470 resistivity logs the e5 surface is characterized by a series of sub parallel southeast trending steps with lower areas between the steps this topography is interpreted to have formed during erosional shoreface retreat in a period of alternating transgression and stillstand of relative sea level tectonic tilting of the basin floor is also suggested by the topography of the erosion surface the tilti g is related to the accretion of exotic terranes and loading the continental margin the erosion surface is overlain by a continuous veneer of conglomerate interpreted as a transgressive lag this conglomerate thickens to 20 m in the lower areas at carrot creek where it is interpreted as a shoreface deposit rather than an offshore bar these shoreface conglomerates form important reservoirs the veneer also thickens to about 9 m in parts of pembina but the thick conglomerates occur not in the lows but on top of the steps reconstruction of the geometry of the steps indicates that at times of unusually high sediment supply during transgression conglomerates were deposited as local bars in the lower shoreface the sandstones and mudstones below the erosion surface at pembina shale out northeastward partly forming a stratigraphic trap however these sediments are also truncated by the e5 erosion surface and buried by transgressive mudstones these mudstones contribute significantly to updip stratigraphic trapping the long narrow sand body trends mapped in pembina and adjacent fields are due to the erosive dissection of an originally extensive and continuous sheet of interbedded sandstones and mudstones and not as has been suggested to an offshore bar origin for the fields

late miocene transcurrent tectonics in nw turkey evidence from palaeomagnetism and 40ar 39ar dating of alkaline volcanic rocks a number of intra continental alkaline volcanic sequences in nw turkey were emplaced along localized extensional gaps within dextral strike slip fault zones prior to the initiation of the north anatolian fault zone this study presents new palaeomagnetic and 40 ar 39 ar geochronological results from the lava flows of nw turkey as a contribution towards understanding the neogene quaternary tectonic evolution of the region and possible roles of block rotations in the kinematic history of the region 40 ar 39 ar analyses of basalt groundmass indicate that the major volume of alkaline lavas of nw turkey spans about 4 million years of episodic volcanic activity palaeomagnetic results reveal clockwise rotations as high as 73 in thrace and 33 anticlockwise rotations in the biga peninsula movement of some of the faults delimiting the areas of lava flows and the timing of volcanic eruptions are both older than the initiation age of the north anatolian fault zone implying that the region experienced transcurrent tectonics during late miocene to pliocene times and that some of the presently active faults in the region are reactivated pre existing structures

tectonic evolution of the marmara sea and its surroundings abstract the basins in the marmara sea are the products of a superimposed evolutionary history defined by two different aged fault systems the early miocene early pliocene thrace eskisehir fault zone and its branches and the late pliocene recent north anatolian fault and its branches the thrace eskisehir fault and its westward branching secondary fault systems define the early neotectonic signature in the region the late neotectonic period started at the end of the early pliocene when the north anatolian fault divided the thrace eskisehir fault into four parts during the late neotectonic period the north anatolian fault extended westward as a number of splays by joining with the ganos bandirma behramkale and manyas edremit fault zones the branches of the north anatolian fault zone nafz caused the evolution of a number of basins which differ in character depending on the trend and past characteristics of the older branches that became connected since the northern branch of the north anatolian fault is connected to the n80 e trending ganos fault zone gfz in the west a single buried fault has developed in the marmara sea causing the well known troughs and ridges superimposed onto the negative flower structure formed by the gfz in the early neotectonic period the middle strand which extends from iznik lake to bandirma is oriented east west up to the n60 e trending bandirma behramkale fault zone then turns southward in the vicinity of bandirma forming a region dominated by compressional tectonics this bending caused n30 e trending tension in addition to the strike slip motion between the eastern part of gemlik bay and bandirma bay the southern branch of the nafz on the other hand produced three pull apart basins with different characteristics along the yenisehir bursa and manyas segments the southern branch of the nafz connected to the manyas edremit fault zone which is oriented n45 e to the south of manyas and the associated bending and rotation caused a n15 e trending extension in addition to the strike slip regime between manyas and uluabat the branches of north anatolian fault cut through the thrace eskisehir fault at three places the east marmara sea region in gemlik bay and to the east of bursa giving lateral offsets of 58 59 7 8 and 10 11 km respectively the cumulative motion is 75 78 km corresponding to the total lateral offset of the north anatolian fault in the region the correlation of these offsets with global positioning system slip vectors and with stratigraphic results implies that the north anatolian fault reached into the marmara sea region about 3 5 million yr ago tectonic processes forming the marmara sea and its environs were initiated by the thrace eskisehir fault and its splays have been most recently controlled by the north anatolian fault and its splays during the last 3 5 million yr

new empirical relationships among magnitude rupture length rupture width rupture area and surface displacement source parameters for historical earthquakes worldwide are compiled to develop a series of empirical relationships among moment magnitude m surface rupture length subsurface rupture length downdip rupture width rupture area and maximum and average displacement per event the resulting data base is a significant update of previous compilations and includes the additional source parameters of seismic moment moment magnitude subsurface rupture length downdip rupture width and average surface displacement each source parameter is classified as reliable or unreliable based on our evaluation of the accuracy of individual values only the reliable source parameters are used in the final analyses in comparing source parameters we note the following trends 1 generally the length of rupture at the surface is equal to 75 of the subsurface rupture length however the ratio of surface rupture length to subsurface rupture length increases with magnitude 2 the average surface displacement per event is about one half the maximum surface displacement per event and 3 the average subsurface displacement on the fault plane is less than the maximum surface displacement but more than the average surface displacement thus for most earthquakes in this data base slip on the fault plane at seismogenic depths is manifested by similar displacements at the surface log linear regressions between earthquake magnitude and surface rupture length subsurface rupture length and rupture area are especially well correlated showing standard deviations of 0 25 to 0 35 magnitude units most relationships are not statistically different at a 95 significance level as a function of the style of faulting thus we consider the regressions for all slip types to be appropriate for most applications regressions between magnitude and displacement magnitude and rupture width and between displacement and rupture length are less well correlated and have larger standard deviation than regressions between magnitude and length or area the large number of data points in most of these regressions and their statistical stability suggest that they are unlikely to change significantly in response to additional data separating the data according to extensional and compressional tectonic environments neither provides statistically different results nor improves the statistical significance of the regressions regressions for cases in which earthquake magnitude is either the independent or the dependent parameter can be used to estimate maximum earthquake magnitudes both for surface faults and for subsurface seismic sources such as blind faults and to estimate the expected surface displacement along a fault for a given size earthquake

soil liquefaction susceptibility and hazard mapping in the residential area of kutahya turkey this study presents the results of both field and laboratory tests that have been undertaken to assess liquefaction susceptibilities of the soils in kutahya city located in the well known seismically active fault zone liquefaction potentials of the sub surface materials at kutahya city were estimated by using the geological aspect and geotechnical methods such as spt method of field testing and the data obtained have been mapped according to susceptibility and hazard the susceptibility map indicated liquefable and marginally liquefable areas in alluvium and non liquefable areas in neogene unit for the magnitude of earthquake of m 6 5 whereas liquefaction hazard map produced by using of liquefaction potential index showed the severity categories from very low to high however a large area in the study area is prone to liquefy according to liquefaction susceptibility map the large parts of the liquefable horizon are mapped as low class of severity by the use of the liquefaction potential index it can be said that hazard mapping of liquefaction for a given site is crucial than producing liquefaction susceptibility map for estimating the severity both the susceptibility and hazard maps should be produced and correlated with each other for planning in an engineering point of view

progradational sequences in miocene shoreline deposits southeastern caliente range california abstract an exceptionally well exposed marine nonmarine transition in middle miocene strata exists in the southeastern caliente range california about 50 individual progradational sequences form a succession that ranges in thickness from approximately 1000 m where predominantly nonmarine to more than 2500 m where predominantly marine paleogeographic evidence in basalt flows near the top of the succession and in overlying fluvial deposits indicates that these middle miocene strata were deposited across a north northwest trending shoreline a complete progradational sequence typically is several meters to a few tens of meters thick and includes strata that represent three intertonguing stratigraphic units individual sequences generally rest on a thin gravel deposit interpreted as a transgressive lag on an erosional surface the gravel is overlain by structureless siltstone or fine grained sandstone deposited at water depths where the rate of faunal mixing exceeded that of production of structures by physical processes these rocks grade upward into bedded fine sandstone deposited closer to shore where physical processes exceeded bioturbation crossbedded lenses of coarse sand or fine gravel in the upper part of this facies suggest the presence of fairly long period surface waves the bedded fine sandstone is sharply ove lain by a cross bedded coarse sandstone facies that is interpreted as a combined offshore bar rip channel surf zone assemblage cross strata dip dominantly offshore suggesting substantial deposition from rip currents a secondary shoreparallel mode of cross strata direction suggests longshore currents produced by surface waves from the northwest the crossbedded coarse grained sandstone grades upward into planar bedded medium grained sandstone that is interpreted as a beach foreshore this facies grades upward through structureless medium grained sandstone into nonmarine or lagoonal red and green mudstone of the caliente formation the middle miocene succession was deposited in a subsiding basin that was otherwise remarkably stable tectonically the position of the strand line differed no more than a few kilometers through a period of 1 to 3 m y the average duration of the transgressive regressive cycles a few tens of thousands of years together with their distribution in groups of three or four in the lower two thirds of the succession is consistent with the pattern of long term climatic cycles produced by periodicity of the earth s solar orbit and may be related to eustatic sea level changes attendant to the development of the antarctic ice cap changes in the pattern of progradation in the upper part of the succession and nearby basaltic eruptions may have been precursors to the onset of movement along th san andreas fault in this area 12 14 m y ago

sea level changes an integrated approach sea level changes an integrated approach in october 1985 sepm sponsored a four day conference entitled sea level changes an integrated approach the purpose of the conference was to provide a forum for an interdisciplinary exchange of ideas on sea level changes and to provide an opportunity for integrating various types of evidence in approaching unresolved issues the conference was successful in bringing together scientists from industry academia and government representing all of the major geosciences disciplines presentations of many new papers plus significant releases of data that were previously held proprietary provided fertile ground for discussion this much cited volume represents the best of the material presented at the conference includes the early vail chart

sedimentary successions formed by fifth order glacio eustatic cycles in the middle to upper quaternary formations of the oga peninsula northeast japan abstract the northern coast of the oga peninsula is a type locality for quaternary sedimentary exposures on the sea of japan side of northeast japan middle to late pleistocene shallow marine to nonmarine sediments are continuously exposed on sea cliffs along the anden coast these sediments have been mapped and classified into nine sedimentary facies based on grain size sedimentary structures intensity of bioturbation and associated fossils the depositional environments and paleo water depths of each facies have been estimated based on comparison with the present sub bottom sedimentary features observed in coastal systems around the oga peninsula on the basis of sedimentary facies analysis variations in the depositional depth through time have been reconstructed and correlated with the specmap 18o curve using four marker tephras as time controls the two curves generally agree between approximately 80 and 450 ka suggesting that the sedimentary cycles at the anden coast faithfully record 5th and 6th order glacio eustatic sea level changes peak to peak comparison between the reconstructed depositional depth curve and the 18o curve reveals that 1 unconformities are formed during the late eustatic sea level falls and or the following lowstands 2 transgressive lag deposits are mainly formed below wave base 3 deepening upward successions which sometimes occur below the ravinement surfaces are formed in the inner part of estuary or barrier island environments where wave action was minor 4 shoaling upward successions formed during eustatic sea level falls are deposited under the influence of intense wave action in a strand plain coastal plain system and 5 the characteristic combination of thinner deepening upward successions and thicker shoaling upward successions reflects the asymmetric pattern of glacio eustatic sea level changes and or lower sediment supply during transgression

deformational behaviour of continental lithosphere deduced from block rotations across the north anatolian fault zone in turkey abstract theoretical considerations of lithosphere deformation across transform plate boundaries predict an expression in terms of 3istributed deformation the magnitude of rotation is expected to diminish away from the fault zone in a way which depends on the length of the fault the amount of displacement and the ductility of the lithosphere palaeomagnetic studies across the north anatolian transform fault zone which separates the eurasian plate and anatolian block in northern turkey show that clockwise rotations predicted from the sense of dextral motion are indeed present and have attained finite rotations of up to 270 during the 5 ma history of neotectonic deformation such rotations are however confined to narrow 10 km wide zones between system bounding faults and appear to have resulted from rotation in ball bearing fashion of equidimensional blocks a few kilometres in size outside of this zone only anticlockwise rotations are observed these are unrelated to deformation across the fault zone and record regional anticlockwise rotation of turkey which is complementing clockwise rotation of greece and accompanying neogene opening of the aegean sea the observed behaviour of continental lithosphere satisfies no plausible value of power law behaviour we therefore conclude that relative motion across this transform boundary occurs as a discrete zone of intense deformation within a brittle layer comprising the seismogenic upper crust this is presumed to be detached from a continuum deformation response to shearing in the lower crust and mantle beneath

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

the sea of marmara a plate boundary sea in an escape tectonic regime abstract the sea of marmara is dissected by two major fault systems the first consists of two east west striking transtensional boundary faults and a number of secondary faults subparallel to them the second is made up of ne sw trending subvertical strike slips and their conjugates oriented nw se that offset the first system these fault systems segment the deep marmara sea into 5 blocks that are either rhomboidal lazy z or wedge shaped three of these blocks may be interpreted as pull apart basins characterized by transtension while the other two sill areas which separate the basins are transpressional push up structures the blocks are subjected to rapid episodic subsidence but they also undergo pervasive vertical motions and possible rotations relative to one another the sedimentary column above the acoustic basement mapped within the sea of marmara can be divided into 3 seismic units a folded and truncated pre transform unit and two syn transform units the lower thick syn transform unit exhibits 3 distinct seismic facies a well stratified basin fill facies cut by subvertical growth faults a push up facies with a contorted or chaotic internal configuration and a slump facies the observed neotectonic and sedimentary regimes result from compressional movement between eurasia and africa which has led to major dextral transform movements along the north anatolian fault zone escape tectonics and from the fact that this fault zone splinters into two overlapping right stepping oblique master faults at the eastern and western border of the sea of marmara respectively

the off fault deformation on the north anatolian fault zone and assessment of slip rate from carbonate veins abstract discrepancies in earthquake characteristics between geodetically determined and geologically observed slip rates are prominent for the eastern part of the north anatolian fault naf zone we investigated the spatial distribution of deformation across a naf fault segment near erzincan ne turkey through field observations of physiographic features along the principle fault and a carbonate filled fissure system we propose that distributed deformation across the principal fault in a stretching zone caused sigmoidal simple shear rotation of the carbonate filled fissure system displacement data of that sigmoidal fissure using isotopic age data of the carbonate fill indicates an off fault deformation rate of 15 90 3 19 mm per year for the holocene which corresponds to at least 50 of the geodetically estimated annual slip across the fault it is critical to take the distributed deformation into account for determining earthquake characteristics of active fault systems

erratum to chemostratigraphic and sedimentological framework of the largest negative carbon isotopic excursion in earth history the neoproterozoic shuram formation nafun group oman j precam res 146 2006 68 92

structural deformation pattern within the nw qaidam basin in the cenozoic era and its tectonic implications abstract the qaidam basin is located in the northeastern tibetan plateau and provides an excellent field laboratory in understanding the history and mechanism of the plateau growth it deformed widely over the northwest during the cenozoic but with little thrust loading along the margins where no foreland depression is observed based on satellite images seismic and borehole data we investigated the structural deformation pattern including the structural style and timing of deformation and its formation mechanism within the northwestern qaidam basin during the cenozoic era mapping of surface geology shows that the modern qaidam basin is characterized by five se trending anticlinal belts each belt consists of several right step en echelon anticlines with plenty of normal and strike slip faults crossing the crests those anticlines are generally dominated by double fault systems at different depths an upper thrust fault system controlling the anticlines identified on the surface and a lower dextral transpressional fault system characterized by typical flower structures they are separated by weak layers in the upper xiaganchaigou or the shangganchaigou formations the upper system yields shortening strain 2 5 times larger than that of the lower system and the additional strain is interpreted to be accommodated by hinge parallel elongation in the upper system growth strata indicate that deformation within the qaidam basin initiated in the middle miocene 15 ma and accelerated in the late miocene 8 ma a simple riedel p shear model is used to explain the deformation mechanism within the northwestern qaidam basin

evolution of neotectonic activity of east anatolian fault system eafs in bingol pull apart basin based on fractal dimension and morphometric indices abstract this study is an attempt of a semi automatic geomorphological gis analysis based on morphometric indices in the study 10 m resolution digital elevation models dems are used to assess the neotectonic signals regarding the recent topographic developments and to attach additional significance to active tectonics in the bingol basin area the methodology incorporates the determination of the structural similarities of the faults in the basins using fractal concepts and the application of four morphometric indices stream power index sp multi resolution index of valley bottom flatness mrvbf terrain ruggedness index tri and valley width to height ratio vf in order to detect the deviation from spatial randomness of the applied indices the weighted correlation coefficient moran s i is used and the results are interpreted at a confidence interval of 99 the spatial distribution of integrated index values is evaluated with the tectonically active fault zones in order to determine the probable activity and the structural deformation in the basin the applied methodology reveals that the fractal analysis of the fault lines and the spatial analysis of the morphometric indices proved to be effective tools in analyzing the tectonic influence of the fault system on the basin area within the basin area a relatively lesser degree of tectonic activity is observed in contrast with the high tectonic activity outside the basin

slip distribution along the north anatolian fault associated with the large earthquakes of the period 1939 to 1967 abstract between 1939 and 1967 six large fault ruptures formed a westward migrating sequence of events along a 900 km long nearly continuous portion of the north anatolian fault for these events the 1939 erzincan 1942 niksar erbaa 1943 tosya 1944 bolu gerede 1957 abant and 1967 mudurnu valley earthquakes i have compiled a record of dextral slip which contains nearly 100 points these data indicate that the amount of slip is irregularly distributed along the 1939 to 1967 rupture zone the maximum slip 7 5 m occurred during the 1939 earthquake in the eastern 150 km of the 900 km long rupture zone dextral offsets diminish very abruptly eastward but very gradually westward the rate of westward decrease in the 1939 to 1967 offsets is only slightly greater than the rate of westward decrease of post miocene displacement along the north anatolian fault this suggests that westward decrease in slip can be expected to be a general characteristic of earthquake ruptures along the north anatolian fault in the future nevertheless within the 1939 to 1967 slip distribution there are three regions that had less slip than the neighboring regions these i interpret as possible sites of large future earthquakes one of these seismic gaps has already experienced another earthquake in 1951 and subsequent creep

the north anatolian fault a new look dedicated to the memory of three pioneers ihsan ketin sirri erinc and melih tokay and a recent student aykut barka who burnt himself out in pursuit of the mysteries of the north anatolian fault abstract the north anatolian fault naf is a 1200 km long dextral strike slip fault zone that formed by progressive strain localization in a generally westerly widening right lateral keirogen in northern turkey mostly along an interface juxtaposing subduction accretion material to its south and older and stiffer continental basements to its north the naf formed approximately 13 to 11 ma ago in the east and propagated westward it reached the sea of marmara no earlier than 200 ka ago although shear related deformation in a broad zone there had already commenced in the late miocene the fault zone has a very distinct morphological expression and is seismically active since the seventeenth century it has shown cyclical seismic behavior with century long cycles beginning in the east and progressing westwa

forced regressions in a sequence stratigraphic framework concepts examples and exploration significance sequence stratigraphic concepts suggest that stratal geometries develop and are largely controlled by changes in relative sea level on the shelf lowstand deposits which form during falls and subsequent stillstands of relative sea level can be recognized by the presence of an unconformity at the base the isolated and basinward position relative to the previous shoreline and the abrupt seaward translation of shallow water and shoreline facies into the basin across an unconformity surface this seaward translation of facies and shoreline regression in response to relative sea level lowering is termed a forced regression a forced regression is independent of variations of sediment flux and is in contrast with normal regressions that occur in response to excess sediment flux relative to space available on the shelf i e accommodation forced regressions commonly are associated with a zone of sedimentary bypass subaerial exposure and possible fluvial erosion between the newly formed and preceding shorelines certain shelf sands previously interpreted as offshore or mid shelf sand bodies thus can be reinterpreted as stranded lowstand shorelines associated with forced regressions this alternative interpretation has economic significance insofar as it suggests different subsurface correlations and reservoir geometries with the potential for development of new play types and enhanced recovery in o der fields examples of forced regression can be observed at a variety of scales and ages several such examples include the modern east coulee fan delta and the lower cretaceous viking formation in alberta canada the quaternary rhone delta and the quaternary hudson valley system

susehri basin an active fault wedge basin on the north anatolian fault zone turkey abstract the susehri section of the north anatolian fault zone nafz is dominated by an active fault wedge basin its recent configuration is a quaternary strike slip depression superimposed on a larger fault controlled fluvial to lacustrine setting inherited from the pliocene in and around the susehri fault wedge basin the nafz is characterized by the north anatolian master fault namf or principal displacement zone pdz and four second order fault sets namely the kelkit akcaa il beyde irmeni and ekenek fault sets the namf cuts through the basin the fault sets border the margins of the basin and impart a double divergence character to the namf which is proposed as an evolutionary model for the susehri fault wedge basin the susehri basin fill deposits of pliocene age rest on the quiet and shallow marine limestones of burdigalian age with a sharp angular unconformity besides the upper half of the pliocene basin fill deposits is dominated by the well developed syndepositional mesofractures which reveal the existence of a right lateral shearing at the time of deposition these observations also imply the emergence of a new tectonic regime after the burdigalian by which time the susehri basin had experienced a subsidence of about 660 m to 1150 m during its evolution on the other hand at the south easternmost end of the susehri basin the lutetian volcano sedimentary sequence of the yesilyayla group is cut and displaced right laterally by about 35 km which is the detectable minimum offset on the nafz finally during the 1939 12 27 erzincan earthquake the erzincan erbaa segment of the nafz was reactivated and several modern faults were produced along these modern faults some natural and man made features were displaced right laterally these offsets vary in decreasing order from 7 5 m near the epicenter at the southeastern end to 3 7 m away from it at the northwestern end of the erzincan erbaa segment of the nafz

late cryogenian neoproterozoic glacial and post glacial successions at the southern margin of the congo craton northern namibia facies palaeogeography and hydrocarbon perspective

tectonic controls of the north anatolian fault system nafs on the geomorphic evolution of the alluvial fans and fan catchments in erzincan pull apart basin turkey abstract the erzincan pull apart basin is located in the eastern section of the north anatolian fault system nafs the tectonic evolution of this basin is mostly controlled by strike slip master faults of the nafs this study examines the topography structure relationships in an effort to evaluate the tectonic signatures in the landscape paying special attention to recent tectonic activity in the study the main focus is on the tectonic controls of the nafs on the geomorphic evolution of alluvial fans and fan catchments in the erzincan pull apart basin the observations of the amount of tilting of the alluvial fans and its relation with morphometric asymmetry factor af hypsometric integral hi fractal analysis of drainage networks d properties of the fan catchments provide valuable information about the tectonic evolution of the basin area the results of the analyses showed that the alluvial fan and fan catchment morphology in the pull apart basin are mainly controlled by the ongoing tectonic activity of the nafs the fault system in the basin has controlled the accommodation space by causing differential subsidence of the basin and aggradation processes by causing channel migration channel incision and tilting the alluvial fans

using mechanical modeling to constrain fault geometries proposed for the northern marmara sea 1 in recognition of potential seismic hazard along the north anatolian fault within the marmara sea geophysical surveys have recently been conducted to collect high resolution bathymetry and seismic reflection data despite the high quality of the data fault interpretations by different authors are varied and a conclusive fault geometry within the marmara sea remains elusive this paper presents a mechanical modeling method for constraining proposed fault geometry interpretations in the model crustal faults within the marmara sea slip in accordance with gps constrained slip rates along deep plate boundary dislocations we test three fault models proposed by others and show that an interpretation with a series of pull apart basins along a master strike slip fault best produces the observed deformation pattern within the marmara sea the locations and relative subsidence of the basins along the northern marmara trough are well matched the computed slip vectors on the faults in the best fitting model indicate that except for small faults bounding the tekirdag basin the faults have dominantly right lateral slip with rakes within 15 of horizontal on the local scale this suggests that interaction between the segmented strike slip faults is the dominant mechanism producing the observed vertical deformation in the marmara sea on the regional scale if the marmara sea faults behaved in this manner over geologic timescales then right lateral plate boundary motion without an additional component of north south extension associated with the aegean sea is sufficient to produce the marmara sea pull apart basin morphology

liquefaction potential and susceptibility mapping in the city of yalova turkey this study presents results of both field and laboratory tests that have been used to asses liquefaction susceptibilities of the soils in yalova city located in the well known seismically active north anatolian fault zone liquefaction potentials of the sub surface materials in yalova city were estimated by using the standard penetration test spt method of field testing the data obtained have been mapped according to susceptibility and the susceptibility maps based on the geotechnical data indicated a moderate to high susceptibility to liquefaction for the magnitude of earthquake of m 7 4 both the high groundwater level and the grain size of the soils in conjunction with the active seismic features of the region result in conditions favourable to the occurrence of liquefaction when the surface and near surface geological conditions were taken under consideration it was seen that the study area s geology is prone to liquefaction having a moderate liquefaction susceptibility if geologic and geomorphological criteria are considered it should be understood that the study area as discussed under the region s geology is susceptible to liquefaction the geotechnical data largely support the geologic based liquefaction susceptibility of the study area

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

slope shelf nearshore depositional sequences with transgressive conglomerate in a miocene backarc and arc junction setting central japan abstract several third order slope shelf nearshore depositional sequences are found in the middle to late miocene aoki and ogawa formations in the southern part of the northern fossa magna region central japan each depositional sequence consists of a transgressive systems tract varying in thickness from several tens of centimetres to about 10 m a falling stage systems tract several tens of metres in thickness and a highstand systems tract 20 80 m thick the highstand systems tract and falling stage systems tract are bounded by the regressive surface of marine erosion each depositional sequence mainly consists of coarse grained sediments the materials of the transgressive conglomerate beds were derived from the gravelly foreshore and upper shoreface by transgressive shoreface erosion the thin and conglomeratic transgressive systems tract indicates that these slope shelf nearshore sequences were deposited on the steep slope area under a rapid transgression therefore these sequences were formed in response to excess sediment supply and a rapid rise in relative sea level at an active margin of the backarc side of the arc trench system

wave formed coarse grained ripples and their relationship to hummocky cross stratification abstract wave formed coarse grained ripples cgr form in water depths ranging from 3 to 160 m on transgressive surfaces in upper and lower shoreface sediments and in finer grained offshore transition deposits cgr have crest spacings of 0 25 3 0 m with amplitudes of 5 35 cm internal stratification is rarely preserved but where present crossbeds dip en echelon away from the ripple crest and individual laminae feather out away from the crest waves that form cgr commonly have wavelengths on the order of 2 5 m with periods of 8 to 14 sec these are not large storm events especially on a geological scale cgr commonly occur in close association laterally and vertically with hummocky cross stratification it is postulated that if sediment is medium to very coarse grained sand or pebbly sand then two dimensional cgr will be formed from oscillatory or oscillatory dominant flow if however sediment is very fine to fine grained sand then three dimensional hummocky cross stratification will be formed the wave conditions under which cgr form are similar to those which would form hummocky cross stratification it is only the grain size that is different reported and calculated wave conditions for hummocky cross stratification are almost identical to those for cgr modern cgr crests trend parallel to the local shoreline and bathymetry as such ancient ripple crests are a useful tool for basin reconstruction

shear wave splitting along a nascent plate boundary the north anatolian fault zone summary the north anatolian fault zone nafz is a transform structure that constitutes the boundary between the anatolian plate to the south and the eurasia plate to the north we analysed the properties of the upper mantle strain field and mantle anisotropy in the vicinity of nafz via splitting of sks and skks phases we used data from the north anatolian fault naf passive seismic experiment this is the first study that analyses the upper mantle anisotropy in this region and our results indicate that the observed upper mantle strain field is uniform underneath the array with consistent ne sw polarization directions for fast split waves the measured lag times between the arrivals of the fast and slow split waves varies from 0 5 to 1 6 s for the study area smaller lag times are obtained consistently in the eastern part of the array however we do not observe any significant variation in either the polarization directions or the delay times across the plate boundary nafz the uniformity of the fast polarization directions throughout the study area and the strength of anisotropy favour an asthenospheric source for the anisotropy the regional tectonic framework favours a sw direction of asthenospheric flow due to the forces acting on the upper mantle exerted by the slab roll back taking place along the aegean and the cyprean subduction zones

provenance of ediacaran sinian sediments in the helanshan area north china craton constraints from u pb geochronology and hf isotopes of detrital zircons abstract the tectonic relationship between the alxa block and the north china craton has long been controversial the helanshan area lies at the western margin of the ordos block and to the east of the alxa block and it contains eidacaran zhengmuguan formation and tuerkeng formation the zhengmuguan formation is made up of tillites limestone and dolomine and the tuerkeng formation consists of silty slate a parallel unconformity marks the boundary between the tuerkeng formation and the early cambrian suyukou formation which is composed mainly of phosphatic pebbly sandstone and sandstone u pb dating ages of detrital zircons in the zhengmuguan and suyukou formations reveal two neoproterozoic age peaks of 818 4 ma n 88 and 905 8 ma n 20 neoproterozoic magmatic events have yet been reported in the basement of the ordos block while some neoproterozoic igneous rocks have been found in the basement of the alxa block moreover the two neoproterozoic age peaks correspond well with the ages of neoproterozoic igneous rocks in alxa block the hf isotopic characteristics of a part of neoproterozoic zircons from the ediacaran zhengmuguan formation in the helanshan area ehf t 7 812 to 3 274 tdmc 2211 1578 ma n 10 are similar to those neoproterozoic igneous zircons from the langshan area ehf t 1 105 to 5 928 tdmc 1 75 1 38 ga n 23 and bayinnuoergong area in the alxa block the parental magmas had a long residency time in the crust it seems therefore that alxa block provenance provided neoproterozoic clastics for helanshan area in ediacaran and alxa block had already been a part of the north china craton by the late neoproterozoic even earlier

tectonostratigraphic evolution of the basins on the southern branch of the north anatolian fault system in the se marmara region turkey the lithostratigraphy of the mekece iznik corridor the geyve pamukova and the iznik basins on the southern branch of the north anatolian fault system nafs sb was investigated in detail the intra basin deposits carried by sakarya river and the drainage systems in the northern and southern elevated blocks of the iznik and geyve pamukova basins have been classified based on their lithofacies characteristics the geyve pamukova basin which has developed with a nne ssw trending transtensional strain was formed as a lazy z shaped and releasing bend or pure strike slip pull apart basin that is related to simple shear right lateral strike slip faulting the iznik basin was formed by a right lateral strike slip faulting kinematics and nne ssw trending transtension as a result of the step over of the northeast trending dirazali fault from the southern edge to the nw trending gurle fault and the western step over of this fault to the e w trending umurbey fault this strike slip setting is also supported by the nw se trending right lateral oblique normal orhangazi fault on the northern edge of the basin according to this the iznik basin can be described as a more advanced stage of a large scale pull apart basin compared with a lazy z shaped and releasing bend or transtensional strain furthermore it is defined as the former stage of an extreme or rhomboid type transtensional pull apart basin

recent behavior of the north anatolian fault insights from an integrated paleoseismological data set 1 the north anatolian fault naf is a right lateral plate boundary fault that arcs across northern turkey for 1500 km almost the entire fault progressively ruptured in the 20th century its cascading style indicating that stress from one fault rupture triggers fault rupture of adjacent segments using published paleoseismic investigations this study integrates all of the existing information about the timing of paleoearthquakes on the naf paleoseismic investigation data are compiled into a database and for each site a bayesian ordering constrained age model is constructed in a consistent framework spatial variability of recurrence intervals suggests a spatial pattern in the behavior of earthquakes on the naf that may correspond to the tectonic provinces within the anatolian plate in the west the shear stress associated with the escaping anatolian plate interplays with the tensile stress associated with the aegean extensional province along this western transtensional section we recognize short recurrence intervals and switching between the furcated fault strands the central section of the naf is translational with little influence of fault normal stresses from other tectonic sources this section tends to rupture in unison or close succession the eastern section of the naf is transpressional due to the compressional fault normal stress associated with the indenting arabian plate along this section the recurrence intervals are bimodal which we attribute to variable normal stress although there are other possible causes

kinematic and structural development of the cankiri basin central anatolia turkey a paleostress inversion study three different deformation phases have been recognized in the southern part of the cankiri basin from 1 the major structures and 2 through using paleostress inversion techniques for fault slip data the deformation phases recognized from the paleostress data are correlated with those recognized from the major structures and dated accordingly the first phase occurred in the late paleocene to pre burdigalian and is characterized by an oblique r2 and nne ssw to ne sw trending subhorizontal r1 and wnw ese to nw se trending r3 patterns which indicate transcurrent deformation associated with a combination of thrusting and strike slip faulting transpression possibly due to indentation of the kirsehir block to the sakarya continent the second phase occurred from the burdigalian to the serravallian and is characterized by a subvertical r1 and oblique r2 and r3 which indicate oblique extension associated with normal faulting possibly due to a post orogenic collapse the third deformation phase is characterized by a vertical r2 while the other stresses were horizontal which indicate regional transcurrent tectonics which is correlated with the current transcurrent tectonics controlled by the north anatolian fault zone d 2003 elsevier science b v all rights reserved

opposed shear senses inferred from neotectonic mesofracture systems in the north anatolian fault zone abstract the 1200 km long north anatolian fault zone is a right lateral intracontinental transform boundary which was initiated in the late neogene sediments of pliocene to holocene age in basins between cerkes and erbaa within the convex northwards arc of the fault zone are deformed by syn sedimentary and post depositional mesoscopic faults and joints the mesofractures which strike obliquely to the fault zone include reverse faults normal faults normal shear joints conjugate vertical joints and strike slip faults each type of structure occurs in two geometrical groups one comprises four systems of fractures the other is made up of five systems the directions of secondary compression and or extension inferred from the first group of mesofractures which are restricted to sediments of pliocene to early pleistocene age are interpreted as being related to left lateral shear along the north anatolian fault zone the directions of compression and or extension inferred from the second group of mesofractures which cut sediments of pliocene to late holocene age were generated during right lateral shear the presence of the second group of mesofractures is understandable because they are related to the shear sense which operates at the present day but those interpreted as being related to left lateral shear are more puzzling their development implies one or more reversals of the dominant sense of displacement several tentative models to explain such reversals are proposed including regional and local influences the latter related to mechanical constraints and or the effects of other fault systems

geophysical analysis of fault geometry and volcanic activity in the erzincan basin central turkey complex evolution of a mature pull apart basin abstract the erzincan basin is one of several neogene sedimentary basins developed by prolonged right lateral strike slip along the north anatolian fault zone nafz the intracontinental transform defining the present boundary between the eurasian plate to the north and accreted anatolian terranes to the south the basin has a strong asymmetry and young

constraints on arabian plate motion and extensional history of the red sea analysis of the geologic and geophysical data from the western and northern margin of the arabian plate combined with data from the red sea gulf of aden leads to an interpretation of arabian plate motion that supports an episodic extensional history in the red sea and gulf of aden phase 1 extension began in medial to late eocene and was caused by the nw propagation of the reoriented central indian ridge spreading center it stretched and thinned continental crust along numerous wrench and normal faults that reactivated preexisting structures first phase extension stopped when the arabian plate terminally sutured to eurasia in the medial miocene and halted northward movement of arabia relative to africa the combined african arabian plates moved north more slowly constricting and thickening continental crust in the bitlis zagros sutures while the red sea remained technically quiescent and accumulated salt by the early pliocene continued northward movement was accommodated by lateral extrusion of large continental wedges north of the bitlis zagros sutures this allowed arabia to move northward faster than africa and reopen the red sea where phase 2 extension was expressed by seafloor spreading extension within the red sea gulf of aden rift system has been controlled by the interactions and effects of two factors 1 convergent processes between the north margin of the arabian plate and the eurasian plate to the north and 2 northwest propagation of extension associated with the medial eocene reorganization of the central indian spreading center

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

strike slip faulting topographic growth and block movements as deduced from drainage anomalies the yesilirmak river basin northern turkey abstract this study aims to understand the various effects of known tectonism on a fluvial network and to interpret the tectonic deformations using described and analysed systematic anomalies in the drainage basin of the yesilirmak river in northern turkey at countermarch this region which is divided into several faulted wedges by right lateral strike slip faulting of the north anatolian fault zone and its individual splays has experienced several moderate to large earthquakes with high amounts of surface ruptures during the historical and instrumental periods the yesilirmak river basin includes several geomorphic imprints of such widespread and frequent strike slip deformations offsets between 750 m and 19 km aligned drainages and linear valleys 170 km are expected geomorphic and tectonic responses to strike slip faulting in the fluvial system we used such indicators to determine the long term effects of strike slip faulting in the yesilirmak river drainage network the measured stream offsets represent decreasing values toward southern splay faults consistent with published geodetic data for the region however some other large scale geomorphic anomalies extracted from the drainage network are not explainable by only strike slip tectonics compressional structures i e anticlines synclines in the region are responsible for such large scale drainage diversions 20 24 km along the river courses although these diversions the north anatolian fault zone is the main driving force shaping present geomorphology on a regional scale the sungurlu ezinepazari fault also plays a critical role in landscape evolution their activities and associated block movements have resulted with tilting processes on the other hand the entire fluvial network should be modified by the sea level changes of the black sea particularly in the late quaternary

failure and flow development of a collapse induced complex landslide the 2005 kuzulu koyulhisar turkey landslide hazard koyulhisar located in a slope of hilly region and constructed in the side of a mountain along the north anatolian fault zone is frequently subject to landslides a catastrophic landslide occurred on the morning of 17 march 2005 in the north of the kuzulu district of koyulhisar sivas turkey this landslide caused widespread loss of life and damage to buildings and lifelines fifteen people were dead and five were injured 21 houses and a minaret were covered and damaged severely the case study presented in this paper describes and analyses the results of the detailed surveys of an interesting landslide in kuzulu district of koyulhisar sivas turkey based on field and laboratory measurements and monitoring of the slide area landslide initiated as a collapse and developed into debris avalanches in the valley this phenomenon caused a disaster in the kuzulu district the importance of this landslide in particular has been recognized both in terms of its consequence for the people and structures and in terms of its role in allowing an understanding of process and properties of landslide triggered by a collapse in limestone karst in view of the potential for such events to occur again in this area and environs understanding of the failure mechanism is very crucial

the north aegean region a tectonic paradox in the past two decades several publications have been presented concerning the recent and active fault geometry kinematics and geodynamics of the aegean region and particularly of the northern sector data and results are often contradictory and because of the complexity of the area most hypotheses and models should be considered carefully the right lateral movement of the north anatolia fault continues into some branches of the north aegean fault system there strike slip motion along ne sw trending faults coexists with dip slip e w trending faults in the frame of an extensional regime related to n s crustal stretching if we take into account the geodynamic environment of the region several mechanical problems arise to the east the aegean is compressed by the westward convergence of anatolia while to the south and west along the hellenic arc a hemiradial compression occurs due to subduction although the north anatolia north aegean trough fault system resembles a restraining bend the whole area is in fact affected by pure extension and local transtension along ne sw trending structures accordingly the major paradox of the area and especially in the western sector fault termination is the occurrence of extension where compression should regionally or at least locally predominate

lower pleistocene to present structural deformation and sequence stratigraphy of the continental shelf offshore eel river basin northern california seismic stratigraphic sequences and deformational features are mapped beneath the continental shelf of the offshore eel river basin of northern california using a closely spaced high resolution multichannel seismic grid geometries of sequences and morphologies of bounding unconformities reflect competing tectonic and glacioeustatic influences producing shifting sedimentation patterns in the offshore basin during the last v1 myr estimated timing of unconformity formation correlates generally with a deep ocean global n 18 o curve both before and after a v500kyr transition from 41 kyr to 100 kyr dominated cycles we suggest that glacioeustatic fluctuations are the dominant control on unconformity formation basinwide however regional tectonic influences on sequence development are also observed folding associated with gorda north america plate convergence ended progressively from south to north between v1 0 ma and v500 ka in response to northward migration of the mendocino triple junction mtj since v500 ka continued encroachment of the mtj produces rotation of preexisting structures uplift of the table bluff anticline tba related periods of channel incision south of the tba and generally reduced sediment preservation across the shelf mtj related uplift may also have induced formation of eel canyon over the past v1 0 myr a dominant northern sediment source becomes progressively less important a southern source probably the paleo eel river has become dominant since v750 ka seismic unconformities fall into two categories 1 irregular surfaces of limited mappable extent interpreted as incision exposure surfaces forming during relative sea level lowstands and 2 smooth laterally extensive regional unconformities interpreted as ravinement surfaces that erode lowstand surfaces in all but deeply incised areas during sea level transgressions a sequence stratigraphic model for sediment deposition and preservation on the eel river shelf predicts that preserved sediment on the eel margin is dominated by fluvially derived highstand silts and muds deposited by longshore directed currents and waves lowstand sediments are preserved only in fluvial channels infilled during late lowstand early transgression preserved transgressive sediments are likely limited to a thin veneer of well sorted coarse sediment or shell debris deposited above the transgressive ravinement future deep coring will be required to confirm these predictions 2002 elsevier science b v all rights reserved

late cenozoic tectonics and volcanism along the north anatolian fault new structural and geochemical data abstract different types of volcanic activity have developed along the north anatolian fault zone naf in turkey detailed analysis of satellite images and digital elevation models dems and field observations have been made in order to understand the tectonics and the distribution of volcanic vents in the anatolian block some faults are oblique to the naf and delimit extensional escape wedges vents rooted on open tension fractures show that emplacement of the volcanism is related to tensional fracturing of the anatolian continental block which we attribute to the onset of free borders in the south and west along the naf earliest extension 1 is directed s to ssw and the latest 2 towards w to wsw parallel to the sinistral slip along the naf major and trace element geochemical data indicate that the dominant calc alkaline rocks are associated with various alkaline lavas k ar ages of the volcanics range from 22 to 8 5 ma in galatia massif 900 to 100 ka in niksar and 3 to 12 ka in erzincan isotopic and trace element data are interpreted as reflecting a dominantly lithospheric mantle source slightly mixed with asthenospheric liquids most magmas were fractionated and contaminated by continental crust during their ascent 1 and 2 tectono volcanic events have propagated through time and space from west to east the 1 extension is late oligocene in the galatia massif late miocene in niksar and late pliocene in erzincan the 2 extension and strike slip event along the naf began in the late miocene in the galatia massif early pliocene in niksar and quaternary in erzincan signature from an asthenospheric source in the second event in the three regions suggests that an ancient suture zone galatia massif and or the lithospheric naf transform niksar and erzincan have served to channel small quantities of asthenospheric melts existing at the base of the lithosphere

chemostratigraphic and sedimentological framework of the largest negative carbon isotopic excursion in earth history the neoproterozoic shuram formation nafun group oman abstract oman records in its neoproterozoic nafun group huqf supergroup an essentially complete carbonate rich ediacaran succession the nafun group overlies the presumed marinoan rift related fiq member ca 635 ma and ends just below the precambrian cambrian boundary 542 ma tectonic subsidence caused by thermal contraction following fiq aged rifting allowed the preservation of about 1 km of postrift stratigraphy with no major stratigraphic breaks the nafun group above the marinoan cap carbonate hadash formation represents two siliciclastic to carbonate grand cycles both initiated by significant transgressions these cycles comprise the masirah bay khufai formations and the shuram buah formations the khufai shuram boundary is associated with the start of a major carbon isotope perturbation the uppermost ramp carbonates of the khufai formation record a smooth decrease in 13c from about 4 to values around 0 followed by two descending steps across which values plunge to a nadir of 12 in the overlying red siltstones and shales interbedded with thin limestones of the shuram formation this fall in isotopic values is temporally rapid and coincident in both shallow and deep water sections in the time span of a single parasequence the 13c nadir is then followed by 50 million years of monotonic recovery the shuram shift represents the largest 13c inorganic carbon negative excursion in earth history although the snowball earth theory links periods of depleted carbon isotopic ratios with periods of global glaciation the non glaciated context of the shuram formation suggests that the causal relationship between global glaciation and negative carbon isotopic excursions is non unique although the precise mechanism driving this major perturbation of the carbon cycle remains enigmatic the long term remineralization of an isotopically depleted organic carbon reservoir in ocean water is a promising candidate

regional patterns of tectonic stress in europe nearly 1500 stress orientation determinations are now available for europe the data come from earthquake focal mechanisms overcoring measurements well bore breakouts hydraulic fracturing measurements and young fault slip studies and sample the stress field from the surface to seismogenic depths three distinct regional patterns of maximum compressive horizontal stress shmax orientation can be defined from these data a consistent nw to nnw shmax stress orientation in western europe a wnw ese shmax orientation in scandinavia similar to western europe but with a larger variability of shmax orientations and a consistent e w shmax orientation and n s extension in the aegean sea and western anatolia the different stress fields can be attributed to plate driving forces acting on the boundaries of the eurasian plate locally modified by lithospheric properties in different regions on average the orientation of maximum stress in western europe is subparallel to the direction of relative plate motion between africa and europe and is rotated 17 clockwise from the direction of absolute plate motion the uniformly oriented stress field in western europe coincides with thin to medium lithospheric thickness approximately 50 90 km and high heat flow values 80 m w m2 in western europe a predominance of strike slip focal mechanisms implies that the intermediate principal stress is vertical the more irregular horizontal stress orientations in scandinavia coincide with thick continental lithosphere 110 170 km and low heat flow 50 m w m2 the cold thick lithosphere in this region may result in lower mean stresses associated with far field tectonic forces and allow the stress field to be more easily perturbed by local effects such as deglaciation flexure and topography the stress field of the aegean sea and western anatolia is consistent with n s extension in a back arc setting behind the hellenic trench subduction zone the stress field is influenced in places by regional geologic structures e g in the western alps where shmax directions show a slight tendency toward a radial stress pattern not all major geologic structures however appear to affect the shmax orientation e g in the vicinity of the rhine rift system horizontal stress orientations are continuous