geophysical studies over a segment of the carlsberg ridge indian ocean abstract the study of magnetic gravity and bathymetric data over a segment of carlsberg ridge between 3 and 4 n latitude and 63 30 and 64 30 e longitude revealed the presence of a prominent n57 w trending rift valley the depth of the valley varies from 3250 to 4400 m and its width varies from 15 to 19 km analysis of the magnetic data leads to the identification of the brunhes matuyama boundary 0 73 ma across the ridge axis the jaramillo event commonly associated with the fast spreading centres is not reflected in the present study the late pliocene recent oceanic crust across part of the carlsberg ridge evolved with an average spreading rate of 1 25 cm yr 1 the rift valley shallows in the southeast narrows in the middle and is deeper and wider toward the northwest the occurrence of large amplitude magnetic and gravity anomalies in association with the bathymetric deep in the northwest within the rift valley is suggested to be a zone of future segmentation of the ridge axis a new transform fault appears to offset the trend of bathymetric and gravity contours in the northwestern part of the study area

phosphorites co rich mn nodules and fe mn crusts from galicia bank ne atlantic reflections of cenozoic tectonics and paleoceanography a wide variety of marine mineral deposits were recovered from 750 to 1400 m water depths on galicia bank iberian margin mineral deposits include 1 carbonate fluorapatite phosphorite slabs and nodules that replaced limestone and preserved original protolith fabric 2 ferromanganese vernadite crusts with high mn and fe mn fe 1 contents and thick stratabound layers consisting mainly of mn up to 27 mno and fe 15 fe2o3 which impregnated and replaced the phosphorite 3 co rich mn nodules are composed of romanechite and todorokite laminae mn rich layers up to 58 mno contain up to 1 8 co 4 goethite nodules with fe up to 67 fe2o3 have low mn and trace metals we interpret this mineralization paragenesis to be related to major changes in oceanographic and tectonic regimes three phosphatization generations formed hardgrounds dated by 87sr 86sr isotopes as late oligocene early miocene and latest early miocene during the latest early miocene the hardground was fractured and breached due to regional intraplate tectonism which was coeval with a widespread regional erosional unconformity the stratabound layers and co rich manganese nodules were derived from low temperature geothermally driven hydrothermal fluids with fluid conduits along reactivated faults during middle and late miocene the introduction of vigorous deep water flow from the arctic generated growth of hydrogenetic ferromanganese crusts finally growth of diagenetic fe rich nodules late pliocene was promoted by the introduction of hypersaline mediterranean outflow water into the atlantic ocean

seismic tomographic imaging of the eastern mediterranean mantle implications for terminal stage subduction the uplift of anatolia and the development of the north anatolian fault

ridge segmentation faulting and crustal thickness in the atlantic ocean the mid atlantic ridge mar between the kane and atlantis fracture zones consists of segments 20 85 km in length1 bull s eye patterns in the mantle bouguer gravity anomaly field2 centred on several segments associated with narrow rift valleys3 have been interpreted as centres of strong mantle upwelling and thick crust here i present a map of normal faults inferred from 5 104 km2of sea beam bathymetry4 along the mar between 28 n and the atlantis fracture zone faults are mapped both on and off ridge using a criterion that distinguishes them from volcanic topography abyssal hill lineations seem to form at the rift valley walls through the growth of the normal faults towards ridge segment ends these faults are more widely spaced with larger throws than those at segment centres and often define the boundaries of the gravity bull s eyes these two different faulting styles which probably reflect changes in lithospheric strength are preserved into the rift mountains large throw faults are highly correlated with the mantle bouguer highs suggesting that amagmatic extension on the large faults contributes to the crustal thinning inferred towards the segment ends

extent of azores plume influence on the mid atlantic ridge north of the hotspot a complete bathymetry and geophysical survey of the recent domain of the mid atlantic ridge north of the azores between 40 30 n and 45 n was achieved during the 1998 triatnord cruise of r v l9atalante interpretation of along track data and geochemical analyses of rock samples show that the surveyed section represents a peculiar section of the mid atlantic ridge this new data set allows us to tentatively place the northern limit of the influence of the azores hotspot on the accretion processes between lat 43 n and 44 n this limit is marked by a 1 wide transition zone this fits well with the asymmetry of the upper mantle thermal structure as previously inferred from seismic tomography and geoid models thus enhancing the links between shallow and deeper accretion processes in a hotspot ridge interaction context observations of along ridge variations of geochemical parameters at various scales shed light on the relations between mantle geochemical heterogeneities and the accretion processes along the ridge axis confirming the asymmetry in the along ridge horizontal extent of the azores plume

upper crust response to geodynamic processes beneath isparta angle sw turkey revealed by cmt solutions of earthquakes abstract the isparta angle is an important area of sw anatolia where extensions in all directions n s ne sw nw se and e w meet these extensions were determined by normal faulting structures as well as by shallow earthquakes all extensions except the e w one were attributed to the deviatoric stresses in relation to slab forces and or extrusion of anatolia the moment tensor inversion of 40 shallow earthquakes which occurred in the inner part of the isparta angle give focal mechanisms mostly indicating normal faulting inversion of all focal mechanisms of the earthquakes obtained from the moment tensor inversion yields normal faulting characterized by an approximately e w n268 e 3 axis the calculated stress ratio r is 0 6944 indicating a triaxial stress state commonly accepted geodynamic models for the eastern mediterranean region do not include plate boundary forces acting in the east or west direction our hypothesis is that the cause of the e w extension is the combined forces of gravitational potential energy and the hot asthenosphere upwelling through a tear fault in the subducted african plate between the hellenic and cyprus arcs beneath the isparta angle

source processes and seismotectonic implications of the 1995 and 1996 cyprus eastern mediterranean region earthquakes abstract the teleseismic body waves of two earthquakes were inverted for their sources to obtain a rupture process for each the february 23 1995 ms 5 8 and october 9 1996 ms 6 8 events took place to the northwest and southwest of cyprus both the earthquakes generated complex body waveforms which were inverted using the method of kikuchi and kanamori 1991 the inversion results suggest that the 1995 and 1996 events were multiple events associated with subevents taking place on different faults located nearby the source regions three subevents were necessary to explain the waveforms of the 1995 earthquake the first subevent showed a predominantly normal faulting mechanism while the second subevent located 20 km to the north of the first subevent had a strike slip mechanism with dip slip component despite the difference in mechanisms both the subevents had slip vectors oriented nearly e w the last subevent was located in the proximity of the first subevent and had a normal faulting mechanism with a slip vector in n s direction the different depths and slip vector directions of the first and third subevents may suggest strain partitioning with depth in the source region of the 1995 event the complex waveforms of the 1996 earthquake were modeled with three subevents too combining the hypocentral distribution of the aftershocks with the inversion results revealed that the first subevent took place on a fault plane dipping about 20 to the east southeast the mechanism of the first subevent together with the azimuthal pulse width distribution suggest that the sense of motion on the fault plane was right lateral strike slip and unilateral rupture propagation we estimate from the major subevent a slip rate of 10 mm year for the african plate the second and third subevents were located 35 km to the southeast of the main shock and had a predominantly normal faulting mechanism with slip vectors in north northwest direction the rupture process analysis of the 1995 and 1996 events suggests that the region to the west of cyprus experiences extensional tectonics

miocene recent evolution of anaximander mountains and finike basin at the junction of hellenic and cyprus arcs eastern mediterranean abstract interpretation of 1750 km of multi channel seismic reflection profiles shows that the region of anaximander mountains sensu lato experienced a protracted miocene contractional tectonic phase characterised by a nearly e w trending and s verging fold thrust belt this tectonic phase culminated during the latest miocene and was replaced in the early mid pliocene by a tectonic regime dominated by transpression and rotation we postulate that during the pliocene quaternary the anaximander mountain sensu stricto and the anaximenes mountain developed as the result of reactivation and uplift and rotation of a linked thick skinned pre messinian imbricate thrust fan in both regions the development of back thrusts accentuated the morphology of these submarine mountains at this time the anaximenes mountain experienced a progressive counterclockwise rotation while the anaxagoras mountain and the florence rise experienced a clockwise rotation creating the present present day arrowhead shaped morphology of the anaximander mountains sensu lato the sirri erinc plateau represents a former miocene fold thrust belt that is transected during the pliocene quaternary by a major transpressional fault system which created a series of closely spaced high angle faults that cut the seafloor creating a corrugated topography a major transfer fault is developed between the anaximander mountain sensu stricto and the sirri erinc plateau which displays 2 km of contractional stratigraphic separation and as much as 40 km of sinistral strike slip the finike basin evolved during the pliocene quaternary as the result of accelerated subsidence caused by the lithospheric loading of the western tauride mountains

the role of seamount volcanism in crustal construction at the mid atlantic ridge 24 30 n an analysis of approximately 6000 km2 of sea beam swaths indicates that the floor of the median valley of the mid atlantic ridge mar between 24 30 n is strewn with near circular volcanoes we have identified 481 seamounts in the height range 50 650 m because many of the features which appear to be seamounts do not meet our criteria fully they have not been counted and our numbers are likely a minimum estimate of the population the large abundance of seamounts on the median valley floor indicates that seamount volcanism plays an important role in the accretionary processes at this section of the mar the summit height distribution of the mar seamount population is consistent with the exponential frequency size distribution model for off axis eastern pacific seamounts jordan et al 1983 smith and jordan 1987 the model parameters for the mar population yield an average of about 195 seamounts per one thousand square kilometers and a characteristic height of about 60 m shape statistics compiled from the 481 seamounts give parameters that are exactly the same or cover the same range in values as those obtained from a study of pacific seamounts in the height range 140 3800 m smith 1988 implying a universal control on seamount construction based on the volcanic morphology we identify 18 spreading segments along the ridge all except two contain a prominent axial volcanic ridge many of the seamounts identified are associated with the axial ridges from the sea beam swaths we infer that the ridges are composed of piled up seamounts and hummocky flows and interpret them to be the primary sites of crustal construction this style of volcanism contrasts strongly with that observed at the east pacific rise where seamounts are virtually absent at the spreading axis the construction of seamounts and hummocky flows may be directly related to the fact that the mar is fed by magma chambers that are limited in size and frequency we suggest that small magma pockets with slow eruption rates produce seamounts either from pipes or initial fissure eruptions that collapse to construct a single edifice small magma bodies with somewhat higher eruption rates produce hummocky fissure fed flows using buoyancy arguments the heights of the mar seamounts are related to the depth of the magma bodies we hypothesize that small magma bodies rise buoyantly to the base of the hydrothermally cooled brittle lid where they are trapped and then erupt if this hypothesis is correct the thickness of the brittle lid controls seamount height and the exponential distribution of seamount summit heights implies that the thickness of the brittle hd follows an exponential distribution in time and space with characteristic thickness 1 4 1 9 km if seamounts and hummocky flows are fed each from their own discrete magma body trapped at the brittle ductile transition then the lower crust of the mar will be made up of the products of a multitude of small plutons

east pacific rise 18 19 s asymmetric spreading and ridge reorientation by ultrafast migration of axial discontinuities a detailed bathymetric side scan and magnetic survey of the east pacific rise out to a seafloor age of 1 ma has been carried out between 18 and 19 s it reveals that some left stepping axial discontinuities have been migrating southward at rates an order of magnitude faster than the spreading rates 1000 mm a or higher these rapid migration events have left on the nazca plate discordant features striking nearly parallel to the ridge axis a discontinuity with an offset of several kilometers has migrated in two stages at around 0 45 and 0 3 ma and has left two large discordant zones consisting of a series of unfaulted hummocky basins bounded to the east by short ridges oriented about n s oblique to the ambient 013 fabric the morphology and reflectivity characteristics of these discordant zones are akin to the overlap basins and abandoned ridge tips which make up the migration trails of large slowly migrating overlapping spreading centers between 18 35 and 19 03 s the ridge axis is flanked a few kilometers to the east by a prominent sedimented ridge previously recognized as a recently abandoned ridge axis the present ridge segment steadily deepens and narrows southward which suggests the abandoned ridge has been rafted onto the nazca plate during the ultrafast southward propagation of the ridge segment rather than by one discrete ridge jump by transferring pacific lithosphere to the nazca plate these migration events account for most of the asymmetric accretion observed faster to the east this process is consistent with the features common to asymmetric spreading namely the sudden onset or demise of asymmetric spreading and the ridge segment to ridge segment variability because the discordant zones left by these rapid migration events are near parallel to the ambient seafloor fabric they are unlikely to be detected by conventional bathymetry or magnetic surveys and so called ridge jumps may actually often represent ultrafast propagation of a ridge segment variations in fault azimuth with age show there has not been any significant change in spreading direction over the past 0 8 m y instead the counterclockwise trend of the east pacific rise relative to the brunhes matuyama reversal 0 78 ma mostly reflects that ultrafast propagation of ridge segments has transferred a larger amount of the pacific lithosphere to the nazca plate at 18 s than at 19 s in keeping with the regional features of the magnetic anomalies we propose that an 8 to 10 km left stepping discontinuity which was located between 17 and 17 30 s at 0 78 ma has been recently redistributed into the present staircase of small left stepping discontinuities between 16 and 19 s this smoothing of the ridge geometry probably occurred through repeated small lateral steps of the ridge segments inside of the discontinuities during ultra fast propagation episodes and may be the consequence of a significant replenishment of the magma reservoir between 17 and 17 30 s during the past 1 m y

early miocene kirka phrigian caldera western turkey eskisehir province preliminary volcanology age and geochemistry data abstract large rhyolitic ignimbrite occurrences are closely connected to the early miocene initiation of extension in the central western anatolia crossing the tavsanli afyon zones field and laboratory data performed at the apex of the eskisehir afyon isparta volcanic area allowed recognition of newly identified caldera structure named here kirka phrigian caldera transtensive distensive tectonic stresses since 25 ma ago resulted in the nnw sse elongation of the magma chamber and influenced the roughly elliptical shape of the subsided block caldera floor the caldera which is roughly oval 24 km 15 km in shape formed during a series of collapse events starting at 19 ma by the generation of a huge volume of extra and intracaldera ignimbrites intracaldera post collapse sedimentation and further volcanism at the northern edge at 18 6 ma were controlled through subsidence related faults with generation of a series of volcanic structures domes and lavas showing a large compositional range enriched mantle components within the subcontinental lithospheric mantle began to melt via decompression melting during the initiation of extension the heat resulting from the fractionation of ascending mantle melts produced the silicic compositions in large mushy crustal reservoirs interaction of these melts with fertile crustal rocks further caused crustal anataxis and consequently two different compositions rhyolite 1 and rhyolite 2 the eruptions of kirka phrigian caldera related ignimbrites were probably triggered by basaltic intrusion rock volumes and geochemical evidence suggest that silicic volcanic rocks come from a long lived complex magma chamber system after caldera generation there was a northern shift to small volume extra and intra caldera episodic rhyolitic basaltic trachy andesitic trachytic and lamproitic volcanism the latter being the youngest 16 2 ma indicating a more primitive magma input which originated in an enriched mantle lithosphere the rock succession provides a direct picture of the state of the magmatic system at the time of eruptions that generated caldera and post caldera structures and offers an excellent example of silicic magma generation and associated potassic and ultrapotassic intermediate mafic rocks in a post collisional extensional setting

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

evolution of the eastern indian ocean since the late cretaceous constraints from geosat altimetry we propose a new model for the tectonic evolution of the eastern indian ocean from the late cretaceous to the present two types of data are used to improve previously published reconstructions first recent reinterpretations of seafloor magnetic anomalies between australia and antarctica and in the wharton basin provide new constraints on spreading rates and the timing of major reorganizations second vertical deflection profiles i e horizontal gravity anomaly derived from 22 repeat cycles of geosat altimeter data reveal the tectonic fabric associated with fracture zones these new geosat data provide tight constraints on paleospreading directions for example three prominent fracture zones can be traced from south of tasmania to the george v basin antarctica providing an important constraint on the relative motions of australia and antarctica through the late eocene in addition the geosat profiles are used to locate the conjugate continental margins and continent ocean boundaries of australia and antarctica as well as the conjugate rifted margins of kerguelen plateau and broken ridge based on a compilation of magnetic anomaly data from the crozet basin the central indian basin the wharton basin and the australian antarctic basin ten plate tectonic reconstructions are proposed reconstructions at chrons 5 11 ma 6 21 ma 13 36 ma and 18 43 ma confirm that the southeast indian ridge behaved as a single plate boundary since chron 18 the constraints from the geosat data provide an improvement in the fit of the kerguelen plateau and broken ridge at chron 20 46 ma to avoid overlaps between broken ridge and the kerguelen plateau prior to their breakup our model includes relative motions between the northern and southern provinces of the kerguelen plateau finally we examine the implications of our model for the relative motions of india australia and antarctica on the tectonic evolution of the kerguelen plateau and broken ridge and the adjacent labuan basin and diamantina zone as well as the emplacement of the ninetyeast ridge and the kerguelen plateau over a fixed hot spot

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

the southwest indian ridge between 49 15 e and 57 e focused accretion and magma redistribution abstract bathymetric gravity magnetic and backscattering strength data have been used to characterise the segmentation of an 800 km long portion of the ultraslow spreading southwest indian ridge swir full rate 14 mm yr between 49 15 e and 57 e this analysis reveals that the segmentation defined by along axis variations of depth and by occurrence of axial offsets does not systematically correspond to the segmentation determined by the along axis variations of backscattering strength mantle bouguer anomaly mba and amplitude of the central magnetic anomalies cma at axial discontinuities with offsets larger than 15 km thin crust and reduced volcanic production are suggested by the occurrence of mba highs almost non existent cma and 50 lower backscattering strength relative to the segment centres by contrast smaller non transform discontinuities with offsets smaller than 15 km correspond to very weak variations or to no variation of the mba the cma or the reflectivity of the seafloor suggesting that there is little or no variation of volcanic production and crustal thickness associated with those small discontinuities these small axial discontinuities bound low relief bathymetric segments 500 700 m corresponding to weak or no mba lows amplitude 1000 m corresponding to large mba lows amplitude 30 mgal we suggest that the magma supply to these low relief segments is controlled by near surface processes such as melt migration and or crustal plumbing from adjacent high relief segments pronounced mba lows at high relief segments are thought to correspond to spreading cells where magma supply is focused in the mantle these spreading cells are spaced by about 100 km along the swir axis we suggest that the spacing of spreading cells on slow spreading ridges is primarily controlled by the spreading rate with larger spacing between spreading cells on ultraslow spreading ridges than on slow spreading ridges

discriminating between different genetic types of marine ferro manganese crusts and nodules based on rare earth elements and yttrium marine ferro manganese fe mn crusts and nodules are metal rich chemical sediments that are archives of paleoceanographic proxies and potential metal resources and targets of deep sea mining traditionally crusts and nodules are subdivided into hydrogenetic diagenetic and hydrothermal types because these are characterized by different compositions and hence economic resource potential a useable genetic classification is not only a tool for geochemical studies but may also help to characterize potential exploration targets we propose two easy to use yet robust discrimination diagrams based on geochemical relationships controlling the rare earths and yttrium rey inventory of marine fe mn oxyhydr oxide deposits the rey are a set of trace elements that show coherent behavior are routinely determined in geochemical studies and for which the analytical quality can easily be evaluated graphs of ce anomaly vs nd concentration and ce anomaly vs y anomaly effectively discriminate between the different types of precipitates regardless of their diverse mineralogical composition both hydrogenetic crusts and nodules show positive ce anomalies negative y anomalies and high nd concentrations of 100 mg kg 1 although nodules tend to have slightly lower nd concentrations than crusts in marked contrast hydrothermal deposits generally yield negative ce anomalies positive y anomalies and low nd concentrations of 10 mg kg 1 in spite of their large geochemical mineralogical and sedimentological diversity diagenetic nodules show negative ce anomalies negative y anomalies and intermediate nd concentrations between 10 and 100 mg kg 1 we discuss the geochemical background of these diagrams the respective sources of rey in the different precipitates and address the processes that control their rey inventory besides the three end members we also use rey systematics to define mixed type diagenetic hydrogenetic nodules and classify well studied international reference standards

miocene recent evolution of the western antalya basin and its linkage with the isparta angle eastern mediterranean abstract interpretation of 9500 km of multichannel seismic reflection profiles showed the presence of two major tectonic histories in western antalya basin spanning from the miocene or older to the pliocene quaternary a prominent fold thrust belt affects the miocene succession in the offshore the thrusts swing from a nw se strike with sw vergence in the northeast of the mapped area to a more northerly strike with westerly vergence at the western shelf edge of the deep basin the miocene deformation appears to continue offshore from the westerly directed thrusting seen onshore that characterizes the eastern edge of the isparta angle the contraction is consistent with the counterclockwise miocene rotation of the western side of the isparta angle determined from paleomagnetic studies the thrust belt forms the western extremity of the wider regional aksu kyrenia misis oroclinal culmination the tectonic activity experienced a period of relative quiescence across the western antalya basin during the messinian a major kinematic change occurred in the pliocene when the regional strain was partitioned into three spatially localized tectonic domains an extensional domain confined to the pliocene quaternary unit 1 occupied the northeastern portion of the study area a predominantly extensional domain with a few re activated pre existing miocene contractional structures occupied the southern and central portion of the study area and an extensional and or transtensional domain occupied the continental shelf and slope in the westernmost antalya basin these complexities relate to strike slip motions as the crustal block within the isparta angle moved northwards relative to the blocks to the north

a satellite image approach to the study of lineaments circular structures and regional geology in the golcuk crater district and its environs isparta sw turkey abstract important volcanic occurrences such as a sub volcanic stock caldera volcano cones circular semicircular and elliptical morphologic structures have been identified in the golcuk crater lake district and surrounding area sw turkey our satellite image analysis shows that the volcanic activity occurred during different volcanic phases maps of lineaments and geology of the region were prepared using colors drainage patterns textural features vegetation cover and morphological forms as interpretation parameters in addition the major fracture directions of the region were detected from lineament analysis as trending ne n and nw the relationship of pliocene golcuk volcanism with tectonism was defined and these data are interpreted the satellite image reveals that the volcanic structures and the golcuk crater generally occur at the intersections of different lineaments where the number of lineaments increases lineament analysis on landsat satellite images is a useful tool for detecting volcanic regions alteration and mineralization zones

in situ gamma source radioactivity measurement in isparta plain turkey results derived from in situ gamma ray spectrometry studies on geological units of the isparta plain situated in the foothills of the golcuk volcano are presented in this study determination of the natural radioactivity and radionuclide concentration has been carried out using 512 channel thallium activated sodium iodide nai ti gamma ray detectors with crystal size 2 2 produced from gf instrument inc measurements were performed on 341 site covering volcanic and non volcanic geological units in the area approximately 256 km2 from the measured gamma ray spectra high activity concentration 40k 238u 232th and air absorbed dose rates were found to be about 1 959 38 443 48 408 63 bq kg and 526 ngy h in the volcanic units in the residential area and its vicinity average concentration value of 40k 238u 232th and absorbed dose rates were determined as about 1 387 63 239 16 234 34 bq kg and 350 ngy h respectively annual effective dose was found as 429 53 sv year in this area while annual effective doses were varying from 208 to 522 80 sv year in the study area contribution in to the background radioactivity level emanated from about 17 58 40k 35 73 238u 46 69 232th in volcanic and materials composed of volcanic units

crustal evolution of the mid atlantic ridge near the fifteen twenty fracture zone in the last 5 ma author posting american geophysical union 2003 this article is posted here by permission of american geophysical union for personal use not for redistribution the definitive version was published in geochemistry geophysics geosystems 4 2003 1024 doi 10 1029 2002gc000364

characteristics and evolution of the segmentation of the mid atlantic ridge between 20 n and 24 n during the last 10 million years abstract high resolution bathymetry and geophysical data collected along the slow spreading axis and flanks of the mid atlantic ridge between 20 n and 24 n reveal the characteristics and history of different wavelengths of segmentation during the last 10 m y the bathymetric data exhibit a morphotectonic pattern dominated by ridge normal and oblique bathymetric lows that partition the ridge flanks into rhomb shaped areas of relatively high elevation at least four different types of oblique bathymetric lows have been identified which represent the off axis traces of axial discontinuities and suggest a complex and ongoing evolution of ridge axis segmentation one group of oblique structures is represented by two deep ridge normal depressions with typical fracture zone characteristics that are connected to the present active transform by oblique depressions near the ridge axis these oblique traces correspond to the southward shift of axial discontinuities associated with the propagation of the ridge axis while maintaining a constant offset of the latter two other types of oblique structures correspond to elongate bathymetric lows and oblique alignments of ridge parallel bathymetric lows symmetric about the ridge axis both types of oblique structures frequently change their orientation from normal to subparallel to the ridge axis and appear to merge and diverge off axis these oblique depressions are characterized by positive filtered mantle bouguer anomalies high magnetizations complex magnetic anomaly patterns and possible exposure of mantle lithologies the ridge segments defined by these oblique depressions lengthen or shorten along the ridge axis with propagation rates varying from 0 to 25 km m y 1 the last and smallest discontinuities observed in this area correspond to small ridge axis offsets and off axis traces identified by alignments of the terminations of abutting abyssal hills the ridge flank morphotectonic patterns produced by the evolution of these elementary segments of accretion may represent temporally variable upwelling volumes of melt the centres of the rhomb shaped areas correspond to maximum crust production and thin lithosphere and the discontinuities correspond to a thick lithosphere with very thin crust and possible outcrops of peridotites we propose a model which accounts for the punctuated injection of magma and the evolution of elementary segments of accretion over periods of several million years

implications of 2007 s earthquake activity in egirdir lake sw anatolia based on moment tensor solutions and inversion of stress state we analyzed the waveforms of the small to moderate sized earthquakes that took place in the northern part of the inner isparta angle ia to retrieve their source parameters and combine these results with the focal mechanism solutions of the larger events that occurred in 2007 in egirdir lake at the apex of ia in total source mechanisms of 20 earthquakes within the magnitude range 3 5 m 5 0 were calculated using a regional moment tensor inversion technique the inversion of the focal mechanisms yields an extensional regime with a nne ssw n38 e trending 3 axis inversion results are related to a mainly wnw ese oriented normal fault beneath egirdir lake the r value of a nne ssw extensional regime is 0 562 showing a triaxial stress state in the region the current stress regime results from complex subduction processes such as slab pull slab break off roll back and or retreating mechanism along the hellenic and cyprus arcs and the southwestward extrusion of the anatolian block since the early pliocene

surface expression of eastern mediterranean slab dynamics neogene topographic and structural evolution of the southwest margin of the central anatolian plateau turkey 1 the southwest margin of the central anatolian plateau has experienced multiple phases of topographic growth including the formation of localized highs prior to the late miocene that were later affected by wholesale uplift of the plateau margin our new biostratigraphic data limit the age of uplifted marine sediments at the southwest plateau margin at 1 5 km elevation to 7 17 ma and regional lithostratigraphic correlations imply that the age is 6 7 ma single grain ca tims u pb zircon analyses from a reworked ash within the marine sediments yield dates as young as 10 6 ma indicating a maximum age that is consistent with the biostratigraphy our structural measurements within the uplifted region and fault inversion modeling agree with previous findings in surrounding regions with early contraction followed by strike slip and extensional deformation during uplift focal mechanisms from shallow earthquakes show that the extensional phase has continued to the present broad similarities in the change in the tectonic stress regime after 8 ma and the onset of surface uplift after 7 ma imply that deep seated process es caused post 7 ma uplift the geometry of lithospheric slabs beneath the plateau margin pliocene to recent alkaline volcanism and the uplift pattern with accompanying normal faulting point toward slab tearing and localized heating at the base of the lithosphere as a probable mechanism for post 7 ma uplift of the southwest margin considering previous work in the region there appears to be an important link between slab dynamics and surface uplift throughout the anatolian plateau s southern margin

anomalous phase association of ree in ferromanganese crusts from indian mid oceanic ridges evidence for large scale dispersion of hydrothermal iron abstract ferromanganese crusts collected at selected locations along the 7000 km long stretch of carlsberg central indian and southwest indian ridges are studied for bulk geochemical composition and distribution of rare earths and yttrium in major geochemical phases exchangeable carbonate mn oxide fe oxyhydroxide and residual silicate the crusts are dominated by vernadite with traces of quartz and calcite a high concentrations of major fe mn trace co ni cu zn and rare earth elements indicates that these crusts are hydrogenous in nature however the negative or no cerium anomalies in the shale normalized ree pattern indicates that some of these crusts are of mixed type hydrogenous and hydrothermal irrespective of their nature mixed or hydrogenous the phase distribution of ree y shows 70 83 of total ree y are associated with fe oxyhydroxide phase whereas only about 17 30 are associated with mn oxide phase such phase distribution is expected in mixed type crusts because it is a combination of hydrothermal where 90 of the total ree y is associated with only fe oxyhydroxide phase and hydrogenous processes where 50 of the total ree y is associated with only fe oxyhydroxide phase conversely the hydrogenous crusts also shows similar phase distributions 70 83 association with fe oxyhydroxide phase which is certainly different from typical hydrogenous crusts where both fe oxyhydroxide and mn oxide phases host equal amounts 50 each the large scale dispersion of hydrothermal particulate iron along the indian ocean ridges is likely to contribute an additional fe bound ree y pool to these crusts the positive yttrium anomaly in mn oxide phase of all these crusts substantiates the hydrothermal contribution

manganese nodules in the eez s of island countries in the southwestern equatorial pacific abstract studies on polymetallic manganese nodules in south equatorial pacific eez s between 0 and 20 s show that ni and cu reach their greatest combined abundances of over 2 between 2 and 8 s on the southern margin of the equatorial zone of high biological productivity in the cook line and phoenix island areas as a result of biological fluxing of ni and cu to the nodules at and just below the calcium carbonate compensation depth ccd by contrast co reaches its greatest abundance of 0 6 south of 8 s in the cook islands area in what are believed to be slowly growing nodules on non biogenic clays well below the ccd where little biological co supply is likely nodule abundances are greatest up to 30 kg m 2 in the co rich area in part due to antarctic bottom water aabw flow giving highest overall metal quantities per square metre in the nodules there particularly of co ellice islands nodules are different from those found in the other island groups studied in that they show features more typical of hydrogenetic ferromanganese oxide crusts than of diagenetically influenced nodules there are approximately 110 10 6 t of combined ni cu co expressed as ni equivalent in the cook islands eez nodules approximately 12 10 6 t in phoenix islands nodules and approximately 1 4 10 6 t in ellice islands nodules in areas of 5kg m 2 nodule abundance

petrology and geochemistry of potassic rocks in the golcuk area isparta sw turkey genesis of enriched alkaline magmas abstract the lower pliocene volcanic rocks occurring in the golcuk area of sw turkey exhibit alkaline major element trends with a general potassic character the development of volcanism can be divided into 2 major stages such as trachytic ancient lavas domes and tephriphonolitic trachyandesitic to trachytic golcuk eruptions ignimbrites lava dome extrusions phreatomagmatic deposits and finally young domes volcanic rocks consist primarily of plagioclase clinopyroxene which ranges in composition from diopside to augite and are commonly zoned biotite and phlogopite amphibole phenocrysts are restricted to the pyroclastic deposits pseudoleucites are also seen only in the lava dome extrusions oxides and apatites are common accessory phenocryst phases as would be expected from their potassic alkaline nature the volcanic rocks of the golcuk area contain high amounts of lile ba sr rb and k lree and zr concentrations of compatible elements such as cr ni and v are very low possibly indicating fractionation of olivine and clinopyroxene correlation of sio2 rb sr and mgo with 87 sr 86 sr 0 703506 0 704142 exhibit an increasing trend in the direction of crustal contamination however the isotopic compositions of sr are not as high to indicate a high level of crustal contamination geochemical data are consistent with the derivation of golcuk volcanic rocks from a metasomatized and or enriched lithospheric mantle source during crustal extension in the area this metasomatism was probably occurred by fluids released from the northward subduction between african and eurasian plates during tertiary as the golcuk volcanic rocks display features of island arc magmas with having high ba nb 28 ratios and nb and ti depletions lower pliocene volcanism in the golcuk was response to extensional tectonics

segmentation and morphology of the central indian ridge between 3 s and 11 s indian ocean abstract the segmentation pattern of 750 km long central indian ridge cir between 3 s and 11 s latitudes in the indian ocean has been studied using multibeam bathymetry and magnetic data twelve ridge segments were identified that are separated by well defined transform faults and non transform discontinuities magnetic model studies qualify the ridge as a slow spreading ridge with average full spreading rates varying from 26 to 38 mm yr the disposition of the magnetic anomalies suggests that the plate opening direction has not changed during the last 0 4 ma period along axis variations in the magnetic anomalies presence of axial volcanic ridges on the inner valley floor variations in the depth and geometry of the rift valley suggest distinct variati ons in the accretionary processes along the ridge based on these characteristics and the segmentation pattern we suggest that ten ridge segments are undergoing less magmatic phase of extension while two segments have shown characteristics of magmatic accretion the linear segments with narrow and shallow rift valley floor and near symmetric magnetic anomalies are identified as segments with magmatic accretion the influence of diffuse plate boundary zone on the young seafloor fabric generated by the cir has been examined the seafloor topography different from the normal ridge parallel fabric observed at few places over the ne flank of the cir is suggested to be the consequence of gradual and progressive influence of the distributed diffuse plate boundary between the indian capricorn plates on the newly generated oceanic lithosphere further we documented distinct ridge transform intersection rti highs three of these rti highs are identified as oceanic core complexes megamullion structures megamullion structures are found to be associated with less magmatic sections increased seismicity has been observed at the less magmatic segment ends suggesting the predominance of tectonic extension prevalent at the sparsely magmatic sections

a comparative analysis of compositional variations in and between marine ferromanganese nodules and crusts in the south pacific and their environmental controls abstract regional variation of mn fe co ni and cu in ferromanganese oxides nodules and crusts in the central south pacific is related to primary productivity oxygen minimum layer and calcium carbonate compensation depth the largely latitudinal influence of these environmental parameters on nodule and crust composition reflects their predominantly latitudinal variation primary productivity is the principal regional environmental control influencing diagenetic enrichment of these elements in nodules through its effect mediated by the ccd on supply and concentration of labile organic matter vs carbonate remains to the sediments it influences hydrogenetic enrichment of these elements in nodules and crusts through its effect mediated by the oxygen minimum layer mainly in the case of crusts on their export from surface waters the elements varying susceptibility to being scavenged or organically bound influences the contrasting composition of diagenetic vs hydrogenetic ferromanganese oxides which is further influenced by depth hydrogenesis is the fundamental process governing nodule and crust formation superimposed on which is diagenesis under specific circumstances both are subject to intermittent interruption diminution and augmentation by changes in environmental parameters application of regionally operative environmental controls locally explains local compositional variations and helps refine exploration criteria for economically viable nodules and crusts

significance of shallow seismic reflection ssr and ground penetrating radar gpr profiling on the modern coast line history of the bedre area egirdir lake isparta turkey abstract lake level changes and settlement places constitute the main problems in controlling the coastal environment along the egirdir lake sw turkey the quaternary geology in the bedre coast was studied based on shallow seismic reflection ssr survey ground penetrating radar gpr profiles and the data derived from boreholes and investigations in the field thus six seismic and five radar facies were determined respectively the geological units from the basement rock to the holocene deposits were imaged by the ssr technique gpr technique is used for the shallower part ranging from the ancient to the modern lacustrin sediments the quaternary lake level changes borehole seismic and radar data indicate that a pond with a connected to the lake around the bedre area existed in the last century sand barriers climate topographical elevation and erosions of the basement rocks control the sedimentation of the back barrier of the coastal line marsh muddies and ancient beach sands are the main sediments of the pond area from the profiles ancient buried sand barriers were also seen in the lake side in our view as the previous lake level dropped from the highstand the ancient sand barrier was formed which divided the lake and the pond and isolated a small inland lake which lies 4 m below the level of the coastal barrier for agricultural purposes artificial man made constructions were done on the barrier and channels thus dry agricultural land appeared in the last 50 years on the pond side

the mid atlantic ridge between 29 n and 31 30 n in the last 10 ma abstract the segmentation of the mid atlantic ridge between 29 n and 31 30 n during the last 10 ma was studied within our survey area the spreading center is segmented at a scale of 25 100 km by non transform discontinuities and by the 70 km offset atlantis transform the morphology of the spreading center differs north and south of the atlantis transform the spreading axis between 30 30 n and 31 30 n consists of enechelon volcanic ridges located within a rift valley with a regional trend of 040 south of the transform the spreading center is associated with a well defined rift valley trending 015 magnetic anomalies and the bathymetric traces left by non transform discontinuities on the flanks of the mid atlantic ridge provide a record of the evolution of this slow spreading center over the last 10 ma migration of non transform offsets was predominantly to the south except perhaps in the last 2 ma the discontinuity traces and the pattern of crustal thickness variations calculated from gravity data suggest that focused mantle upwelling has been maintained for at least 10 ma south of 30 30 n in contrast north of 30 30 n the present segmentation configuration and the mantle upwelling centers inferred from gravity data appear to have been established more recently the orientation of the bathymetric traces suggests that the migration of non transform offsets is not controlled by the motion of the ridge axis with respect to the mantle the evolution of the spreading center and the pattern of segmentation is influenced by relative plate motion changes and by local processes perhaps related to the amount of melt delivered to spreading segments relative plate motion changes over the last 10 ma in our survey area have included a decrease in spreading rate from 32 mm a 1 to 24 mm a 1 as well as a clockwise change in spreading direction of 13 between anomalies 5 and 4 followed by a counterclockwise change of 4 between anomaly 4 and the present interpretation of magnetic anomalies indicates that there are significant variations in spreading asymmetry and rate within and between segments for a given anomaly time these differences as well as variations in crustal thickness inferred from gravity data on the flanks of spreading segments indicate that magmatic and tectonic activity are in general not coordinated between adjacent spreading segments

variation in cross sectional area of the axial ridge along the east pacific rise evidence for the magmatic budget of a fast spreading center along the fast and ultrafast spreading east pacific rise the cross sectional area of the axial ridge varies significantly over length scales similar to its morphologic segmentation using an automated method we measure the ridge area volume per kilometer along axis where there is complete bathymetric coverage along 3500 km of the northern and southern east pacific rise our two study areas encompass numerous transform faults large overlapping spreading centers small overlapping spreading centers and smaller discontinuities first second third and fourth order discontinuities the cross sectional area variation mimics the undulation of the ridge crest depth local area maxima occur toward the middle of segments and the axial area decreases by 40 or more at first and second order discontinuities third order discontinuities are generally marked by smaller disruptions in the ridge area and fourth order offsets do not systematically correspond with features of the cross sectional area profile the correlation between shallower ridges and larger ridge areas breaks down at some locations because axial cross sectional area represents a longer term average of the ridge s magmatic state than axial depth a correlation between large ridge areas and negative residual gravity anomalies indicates that inflated ridges are underlain by low density crust and mantle also a correlation between larger area and higher mgo content of axial basalts suggests that inflated areas generally erupt hotter magmas which are presumably supplied more rapidly to the neovolcanic zone the cross sectional area of the axial ridge appears to correlate with the width of the axis centered low velocity zone in the crust these observations as well as the absence of large relict axial ridges off axis indicate that the axial ridge originates from buoyancy due to thermal expansion and the presence of melt in the crust and mantle within about 10 km of the rise axis portions of the northern east pacific rise underlain by a magma chamber reflector generally occur where the ridge cross sectional area is greatest this supports the connection between processes which inflate the axial ridge and those which heat the crust and upper mantle and produce melt thus while the axial high on fast spreading centers resembles a constructional volcano in cross section it is more like a long narrow balloon whose cross sectional area is a sensitive indicator of magma supply using this relationship we predict with 75 confidence that at least 45 of the unsurveyed northern east pacific rise 18 n to 13 n and 9 n to 5 n and at least 60 of the southern east pacific rise 4 s to 23 s is underlain by a magma chamber reflector

petrology and geochemistry of augite trachytes and porphyritic trachytes from the golcuk volcanic region isparta sw turkey a case study abstract the plio quaternary alkaline volcanic rocks at golcuk isparta sw turkey include older porphyritic trachytes augite trachytes and younger trachyandesitic and tephriphonolitic dikes in order to better understand their pre eruptive evolution the geochemical variations of porphyritic trachytes and augite trachytes have been modeled quantitatively using the melts algorithm ghiorso and sack 1995 their geochemical variations are also compared with those of the younger series results show that two distinct magma series trachyte trachyandesite and tephriphonolite governed the petrogenesis of golcuk volcanic rocks geochemistry of the trachytic trachyandesitic series is controlled predominantly by clinopyroxene and plagioclase fractionation at a shallow depth under oxygen fugacity conditions two units above the qfm buffer melts calculations also show that the crystallisation of trachytic trachyandesitic magma produces clinopyroxene plagioclase alkali feldspar biotite apatite and magnetite quartz consistent with the mineralogy of the augite trachyte porphyritic trachyte and trachyandesitic dikes

deep ocean mineral deposits as a source of critical metals for high and green technology applications comparison with land based resources abstract ferromanganese fe mn crusts are strongly enriched relative to the earth s lithosphere in many rare and critical metals including co te mo bi pt w zr nb y and rare earth elements rees fe mn nodules are strongly enriched in ni cu co mo zr li y and rees compared to fe mn crusts nodules are more enriched in ni cu and li with subequal amounts of mo and crusts are more enriched in the other metals the metal ions and complexes in seawater are sorbed onto the two major host phases feo oh with a positively charged surface and mno 2 with a negatively charged surface metals are also derived from diagenetically modified sediment pore fluids and incorporated into most nodules seafloor massive sulfides sms especially those in arc and back arc settings can also be enriched in rare metals and metalloids such as cd ga ge in as sb and se metal grades for the elements of economic interest in sms cu zn au ag are much greater than those in land based volcanogenic massive sulfides however their tonnage throughout the global ocean is poorly known and grade tonnage comparisons with land based deposits would be premature the clarion clipperton fe mn nodule zone ccz in the ne pacific and the prime fe mn crust zone pcz in the central pacific are the areas of greatest economic interest for nodules and crusts and grades and tonnages for those areas are moderately well known we compare the grades and tonnages of nodules and crusts in those two areas with the global terrestrial reserves and resources nodules in the ccz have more tl 6000 times mn te ni co and y than the entire global terrestrial reserve base for those metals the ccz nodules also contain significant amounts of cu mo w li nb and rare earth oxides reo compared to the global land based reserves fe mn crusts in the pcz have significantly more tl 1700 times te 10 times more co and y than the entire terrestrial reserve base other metals of significance in the pcz crusts relative to the total global land based reserves are bi reo nb and w ccz nodules and pcz crusts are also compared with the two largest existing land based ree mines bayan obo in china and mountain pass in the usa the land based deposits are higher grade but lower tonnage deposits notably both land based deposits have

biogenic mineralization in the ferromanganese nodules and crusts from the south china sea abstract global marine ferromanganese fe mn nodules and crusts host immense metal resources and the metal enrichment mechanism is still in dispute the south china sea scs is one of the largest marginal seas in the western pacific and its northern slope is a passive continental margin with high sedimentary rate a large amount of ferromanganese nodules and crusts have been discovered in the scs northern slope previous investigations shown that the scs nodules crusts are often smaller and thinner and contain higher si and al but lower mn co and ni than the western pacific nodules and crusts in this study high resolution scanning electron microscope hr sem and energy dispersive spectrometer eds were performed to explore the microorganism activities with respect to the nodules crusts formation various biogenic signature and microfossils in the scs fe mn nodules crusts are recorded these bio marks and microfossils present several morphological types tubiform burrows bulbiform organism fossils mould structures cylindrical protozoan globular growth structures isolated spheroidal bacteria and biofilms these mineralized bio marks and microfossils are mostly protozoans belonging to various bacteria biofilm diatoms and coccoliths with mn and or fe on their surface using the electron probe micro analyzer epma the microfossil rich areas contain higher mn than the surrounding microfossil poor areas are observed the abundance of bio marks and microfossils and their geochemical features support a dominant role of microorganism activities in the scs nodule crustal formation we proposed that microorganisms may have served as seeds templates to induce mineral deposition in the nodules and crusts and chemical oxidation and other abiotic mechanisms also contribute to the fe mn oxide formation the biogenic hypothesis provides another perspective to further understand the formation of deep marine fe mn nodules crusts and will be important for exploration of fe and mn metals in the future

late miocene recent evolution of the finike basin and its linkages with the beydaglari complex and the anaximander mountains eastern mediterranean abstract interpretation of 2500 km of high resolution multi channel seismic reflection profiles shows that the finike basin evolved during the pliocene quaternary as the result of dramatic subsidence associated with loading of large imbricate thrust panels that carry the western tauride mountains in the north in the late miocene the stacked seaward prograded quaternary deltas presently resting at 1000 1500 m water depths corroborate the rapid subsidence of the region the ubiquitous presence of evaporites in the 2000 2400 m deep antalya basin and their absence in the 3000 3200 m deep finike basin suggest that the morphology of the finike basin and environs must have been considerably different during the messinian and that this region must have remained above the depositional base of evaporites during this time the transition from the messinian to the pliocene quaternary is marked by partitioning of stress into several discrete spatial domains a dextral strike slip fault zone developed along the western antalya basin extending from the apex of the isparta angle southward into the anaximander mountains this fault zone referred to as the antalya fault zone transected the anaximander mountains sensu lato separating the anaxagoras mountain from the anaximander and anaximenes mountains hence the finike basin sirri erinc plateau and the anaximander and anaximenes mountains remained part of the onland beydaglari block and experienced 20 counterclockwise rotation during the late miocene we envisage the boundaries of the beydaglari block as the burdur fethiye fault zone in the west the newly delineated antalya fault zone in the east and the east west trending sector of the sirri erinc plateau in the southwest kinematic evaluation of the structural elements mapped across the finike basin and the sirri erinc plateau suggest that two additional strike slip zones developed during the pliocene quaternary relaying the stress between the antalya fault zone in the east and the pliny strabo fault zone in the west

fast rift propagation at a slow spreading ridge bathymetric magnetic gravity and morphologic data from the flank of the slow spreading mid atlantic ridge reveal obliquely oriented features that offset magnetic isochrons and morphological patterns within individual ridge segments these features form angles of 10 40 with the isochrons and are inferred to result from rift propagation at rates several times the spreading rate representing the fastest propagators yet observed at a slow spreading ridge these fast propagators appear to have formed as a result of tectonic extension migrating along ridge segments as the segments change from more magmatic to less magmatic periods of spreading

late cenozoic stress state distributions at the intersection of the hellenic and cyprus arcs sw turkey abstract the history of the late cenozoic stress regime was determined for an area between the gulfs of fethiye and antalya fault kinematic analysis and inversion of focal mechanisms of shallow earthquakes reveal significant evolution of the regional stress regime in sw anatolia i e the area of interaction between the hellenic and cyprus arcs from the mio pliocene to the present time fault kinematic analysis yields two different normal faulting stress regimes along the southwestern part of fethiye burdur fault zone e g in and around cameli basin zone a1 and two different strike slip to normal faulting stress regimes characterized by a roughly orthogonal set of extensional axes between fethiye and demre zone b with an older nw se 3 axis for mio pliocene and a younger ne sw 3 axis for plio quaternary time inversion of focal mechanisms of the earthquakes occurring in zone a1 provides an extensional stress state with approximately n s 3 axis inversion of those occurring in zone b south of zone a1 yields a dominantly strike slip stress state with a ne sw 3 axis and a nw se 1 axis respectively the inversion slip vectors from fault planes yield a consistent normal faulting stress regime in burdur basin and its surroundings i e along the northeastern part of fethiye burdur fault zone zone a2 during plio quaternary continuing into recent time as indicated by earthquake focal mechanism inversions both states have a consistent nw se 3 axis fault kinematic analysis indicates nw se extension acting in zone c subarea between demre and antalya south of zone a2 during mio pliocene time the inversion of focal mechanisms yields normal faulting also characterized by a consistent nw se 3 axis the nearly orthogonal extensional stress regimes nw se and ne sw obtained by inversion of both measured and seismic faults seem to have been acting contemporaneously with each other at different intensities from the mio pliocene onwards in sw turkey this may be attributed to the geodynamic effects related to the subduction of the african plate beneath anatolia diffusing along the hellenic and cyprus arcs and in the west southwestward extrusion of anatolia the cause of the early nw se extension is the slab pull force due to the subduction process along the cyprus arc considered to be dominant until the plio quaternary in the western part of the study area in zones a1 and b the dominant status of the cyprus arc continues today in the eastern part of study area in zones a2 and c the later ne sw to present day approximately n s extension dominant since the plio quaternary is related to the combined forces of the anatolian extrusion and the subduction process along the hellenic arc

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

crustal structure of the mid atlantic ridge at 23 n from seismic refraction studies an explosive seismic refraction experiment using four ocean bottom hydrophone receivers was carried out along a 120 km long section of the mid atlantic ridge mar median valley at latitude 23 n immediately south of its intersection with the kane fracture zone the data are interpreted in terms of laterally homogeneous horizontally layered structures using travel time inversion and synthetic seismogram modeling techniques these solutions are combined using two dimensional ray tracing to produce a single model defining the major along axis structural changes occurring beneath this section of the median valley with the exception of slightly low layer 3 velocities the crust beneath several tens of kilometers of the mar median valley has all the characteristics of simple mature ocean crust including a well defined moho transition zone 8 km s upper mantle velocities and a total crustal thickness of 6 7 km no evidence is found for the presence of a steady state axial magma chamber in the crust or upper mantle and the excellent propagation characteristics and orderly amplitude versus range relationships imply the existence of a considerable degree of lateral homogeneity beneath the median valley over distances of several tens of kilometers along axis we infer from these observations that the basic seismic characteristics of the ocean crust are frozen in in a time period less than that separating the major volcanic injection events 10 000 50 000 years by hydrothermal circulation penetrating to the base of the crust along the 100 km long ridge segment studied here two major along axis structural changes occur the first is a 10 to 15 km wide along axis zone of lowered velocities in the lower crust centered beneath a major along axis topographic high this is interpreted to be the remnants of the most recent phase of injection that has temporarily left behind it a region of elevated temperatures and pervasive cracking and thus reduced velocities the second occurs abruptly at latitude 23 15 n and is accompanied by both a major change in rift valley and crestal mountain morphology and the apparent noncoincidence of the median valley and central magnetic anomaly north of this boundary the 30 km long ridge segment that abuts the kane fracture zone has a crustal thickness of 4 5 km and no distinctive layering to produce the characteristic amplitude patterns that typify mature oceanic crust interpretation of the cause of this structural change is uncertain but may be related to local tectonic events perhaps a recent 10 to 20 km ridge jump to the east

different stress states in the burdur isparta region sw turkey since late miocene times a reflection of a transient stress regime abstract the burdur isparta region is a transitional zone between two distinct neotectonic domains in turkey the burdur graben system as the northeastern part of the fethiye burdur fault zone and the kovada graben at the apex of the isparta angle each domain represents a particular stress regime fault data from unconsolidated pliocene and quaternary deposits were combined with stress states deduced from pre pliocene consolidated rocks in order to reconstruct the stress field evolution in the study area since late miocene different stress states were identified they were put in a stratigraphic framework and u th dating of fault related calcite precipitates proved to be an additional tool in constraining the history of the stress states the reconstructed history reflects a transient stress regime the evolving stress field indicates that the influence of the kovada stress regime fades through time and that the influence of the burdur stress regime is gaining importance suggesting a northeastwards progression of the fethiye burdur fault zone

segmentation of the mid atlantic ridge between 24 n and 30 40 n the mid atlantic ridge mar extends for over 12 000 km from iceland to the bouvet triple junction in the south atlantic most of our knowledge of the geology of this slow spreading centre comes either from widely spaced low resolution echo sounding lines or from detailed studies of small areas using deep towed instruments or submarines high resolution multibeam bathy metry1 2 has been insufficient to define the variability of accretionary processes along this plate boundary here we present the results of a recent investigation of a 800 km long section of the mar carried out using the multibeam echo sounder seabeam3 analysis of these data reveals the scale and nature of the segmentation of the mar between the kane fracture zone 24 n and latitude 30 40 n

source inversion of the october 1 1995 dinar earthquake ms 6 1 a rupture model with implications for seismotectonics in sw turkey abstract an earthquake of ms 6 1 devastated the town of dinar sw turkey population 35 000 on october 1 1995 killing 90 people and destroying 30 of the town the earthquake generated complex body waveforms varying with azimuth at teleseismic distances the method of complex body waveform inversion developed by kikuchi and kanamori 1991 was used to infer a source process for the earthquake two subevents were necessary to explain the observed seismic records the inversion result suggests that the dinar earthquake initiated at the se end of the dinar fault with a subevent of seismic moment mo 0 5 1018 n m six seconds later the second subevent took place about 10 km to the northwest of the first subevent with a seismic moment a few times larger than the first the cmt depths of the first and second subevents were found to be 10 and 15 km respectively both subevents had a predominantly normal faulting mechanism with slip vectors oriented ne sw showing good agreement with the velocity vectors obtained from the recent slr and gps studies as well as with the regional stress orientation obtained from geological data the main shock was preceded by foreshock activity concentrated at the se end of the dinar fault where the first subevent took place while the aftershock activity was concentrated in the vicinity of the second subevent the spatial distribution of the foreshock and the aftershock activities and the locations of the subevents suggest that the first subevent broke an asperity and the second subevent broke a barrier on the fault following the definition by aki 1984 of an asperity and barrier earthquake model about 10 km of surface ruptures were associated with the earthquake while the estimates yield a rupture length of 25 km the calculated source parameters of the subevents and their locations suggest that the surface ruptures were probably associated with the first subevent the estimates also show that the rupture zones of the two subevents overlapped where the maximum vertical displacement was observed

widespread tectonic extension at the central indian ridge between 8 s and 18 s abstract the middle part of the central indian ridge mcir between 8 s and 18 s is representative of mid ocean ridges in the indian ocean but has not previously been systematically surveyed here we present results from the first high resolution mapping survey over both on and off axis sections of the mcir including multibeam bathymetry magnetics hydrocasting and seabed sampling the 700 km long mcir consists of six first order segments that are offset by 30 km along well developed transform faults three of the first order segments are further divided into seven second order segments with

building the crust at the mid atlantic ridge the morphology of the sea floor at mid ocean ridge spreading centres provides a key to understanding how ocean crust is constructed images of the axial zone of the slow spreading mid atlantic ridge obtained at a range of spatial scales show that crustal construction is complex and highly variable reflecting an underlying three dimensional variability in magmatic tectonic and hydrothermal processes

ni cu co rich hydrothermal manganese mineralization in the wallis and futuna back arc environment sw pacific abstract the wallis and futuna back arc system is a complex area composed of at least two active oceanic spreading centers the futuna and alofi spreading centers and young volcanic zones characterized by diffuse magmatism locally affected by the samoan hotspot this geological setting is favorable to the establishment of hydrothermal systems in the form of either high temperature ht hydrothermal venting or low temperature lt diffuse flow during the 2010 futuna cruise aboard the r v l atalante three remarkable inactive lt fe si mn deposits were discovered utu uli anakele and utu sega some of the mn rich precipitates discovered exhibit the highest base metals concentrations so far recorded in ferromanganese rocks including in the well documented hydrogenetic crusts and polymetallic nodules the deposits lie on top of volcanoes and formed in close association with the volcanic facies the manganese mineralization occurs in the form of massive layered crusts and mn rich cements within strongly altered basaltic pyroclastic rocks brecciated lavas and more rarely in sediments field observations and mineralogical and chemical studies support a hydrothermal origin for the mineralization and show that nickel cobalt and copper enrichments are controlled by the precipitation of 7 a and 10 a manganates the conventional geochemical classifications e g bonatti et al 1972 used to decipher the origin of mn mineralization cannot be used for this new type of deposit and new robust discrimination diagrams need to be established we suggest that the unusual enrichment of metals recorded in our samples is due to i a lack of precipitation of high temperature massive sulfides at depths that would have retained metals e g cu ni co ii isolation of the hydrothermal system thereby avoiding ni co and cu losses in the water column and iii the ability of birnessite and buserite todorokite to scavenge co ni and cu from aqueous fluids the utu uli and anakele deposits share certain characteristics with the active hydrothermal system at loihi seamount e g the depth of mineralization relationships with pyroclastic volcanoes and the influence of a mantle plume source and thus might represent late stage products of this specific type of hydrothermal activity elsewhere the co rich mineralization of the calatrava volcanic field cvf in spain may be a potential analog of the utu sega deposit the mn co deposits of the cvf formed in close proximity to pliocene volcanic rocks metals were transported by epithermal hydrothermal solutions with high fo 2 and cobalt was scavenged by mn oxides together with the well documented stratabound mn deposits gonzalez et al 2016 hein et al 2008 hein et al 1996 the mn deposits discovered in the wallis and futuna back arc provide crucial insights into lt hydrothermal activity in the deep ocean the metal rich character of this lt hydrothermal activity may be of major importance for future research on the net flux of hydrothermally derived metals e g ni co cu to the open ocean

ultramafic and gabbroic exposures at the mid atlantic ridge geological mapping in the 15 n region abstract the outcrops of mantle derived ultramafic rocks in the 15 n region are the most extensive yet reported for the mid atlantic ridge north of the fifteen twenty fracture zone these outcrops form a belt at least 20 km long along the west wall of the axial valley and also crop out on the east axial valley wall ultramafic rocks also crop out extensively south of the fifteen twenty fracture zone based on dredging and on a morphological analysis of the bathymetric map we propose that ultramafic outcrops may be common in the crust formed between 14 30 n and 15 50 n during at least the past 2 4 m y moderately dipping fault planes and large expanses of tectonic breccia have been observed during dives on the ultramafic outcrops diving observations also show that the ultramafic rocks are capped in stratigraphic contact by a thin layer of basalt this suggests that these rocks were tectonically emplaced at the axial seafloor or very close to it then uplifted in the footwall of the faults that bound the axial valley the occurrence of ultramafic rocks on both walls of the axial valley may be due to frequent changes of faulting polarity in the axial region instead of one master shear zone there would be a complex array of cross cutting conjugate faults and shear zones that could jump inward in the axial domain as spreading proceeds

late cenozoic stress field in the cameli basin sw turkey a history of deformation has been determined for the cameli basin located in the western part of the major fethiye burdur fault zone interpreted as the on land continuation of pliny strabo fault system e g eastern boundary of the hellenic arc inversion of fault slip vectors affecting mio pliocene to quaternary formations in the cameli basin in the southwestern segment of the transtensional fethiye burdur fault zone yields two different normal faulting stress regimes characterized by a roughly orthogonal set of extensional axes a nw se n129 19 e 3 axis and a ne sw n50 16 e 3 axis the orientation of fault sets is predominantly around the ne sw direction in the major fethiye burdur fault zone making the extension nw se the mean r values are 0 74 and 0 69 for both extensions indicating a triaxial stress state which is clearly different from radial extension and from transitional to strike slip stress state the nw se extension is probably responsible for the formation of the cameli basin during mio pliocene time in contrast the inversion of focal mechanism solutions of shallow earthquakes occurring within the cameli basin identifies a present day predominantly extensional stress regime characterized by an approximately n s n184 e 3 axis which has an r value of 0 637 indicating a triaxial stress state the nearly orthogonal extensional stress regimes seem to have been acting contemporaneously with each other at different intensities from the mio pliocene onwards in sw turkey this may be attributed to the geodynamic effects related to the subduction of the african plate beneath anatolia diffusing along hellenic and cyprus arcs and in the west southwestward extrusion of anatolia our hypothesis is that the cause of the early nw se extension is the slab pull force due to the subduction process along the cyprus arc considered to be dominant up to plio quaternary the later ne sw to present day n s extension dominant since the plio quaternary is related to the combined forces of the anatolian extrusion and the subduction process along the hellenic arc

evidence from gravity data for focused magmatic accretion along the mid atlantic ridge gravity data from the mid atlantic ridge between latitudes 27 50 n and 30 40 n show that the accretion of magma at the ridge is focused at discrete centres along the spreading axis large positive gravity anomalies equivalent to reductions of almost 50 in crustal thickness are observed over non transform discontinuities bounding spreading segments

ridge jumps and propagations in the south atlantic ocean the normal pattern of mid ocean ridge divergent plate boundaries comprises straight spreading segments with narrow zones of crustal accretion bounded by transform faults where these segments are offset normally the configuration of spreading segments and transform faults is stable for long periods but in places on fast and medium rate spreading ridges the transform offsets have propagated along the ridge axis as some spreading segments have grown at the expense of adjacent ones1 7 although such behaviour has hitherto not been well documented on slow spreading ridges we have mapped multiple ridge jumps and propagating rifts in two areas of the slow spreading 18 mm yr 1 half rate south atlantic ridge crest we attribute this anomalous behaviour in the south atlantic to the presence of hotspots near our study areas causing elevated asthenospheric mantle temperatures and lateral mantle flow with consequent excess volcanism and disruption of the normally well focused melt delivery processes at the ridge crest

hydrothermal plumes over the carlsberg ridge indian ocean 1 indian ocean ridges north of the rodriguez triple junction remain poorly explored for seafloor hydrothermal activity with only two active sites confirmed north of 25 s we conducted water column surveys and sampling in 2007 and 2009 to search for hydrothermal plumes over a segment of the carlsberg ridge here we report evidence for two separate vent fields one near 3 42 n 63 40 e and another near 3 41 5 n 63 50 e on a segment that is apparently sparsely magmatic both sites appear to be located on off axis highs at the top of the southern axial valley wall at depths of 3600 m or shallower 1000 m above the valley floor at the 63 40 e site plume sampling found local maxima in light scattering temperature anomaly oxidation reduction potential orp dissolved mn and3he no water samples are available from the 63 50 e site but it showed robust light scattering and orp anomalies at multiple depths implying multiple sources orp anomalies are very short lived so the strong signals at both sites suggest that fluid sources lie within a few kilometers or less from the plume sampling locations although ultramafic rocks have been recovered near these sites the light scattering and dissolved mn anomalies imply that the plumes do not arise from a system driven solely by exothermic serpentinization e g lost city instead the source fluids may be a product of both ultramafic and basaltic gabbroic fluid rock interaction similar to the rainbow and logatchev fields on the mid atlantic ridge

chronology of the transition from a spreading ridge to an accretional seamount in the marsili backarc basin tyrrhenian sea inversion of new high resolution magnetic data from the marsili seamount and the surrounding basin in the tyrrhenian sea reveals nne ssw magnetization stripes ranging from the matuyama chron to the brunhes chron including the short positive jaramillo subchron the detailed magnetic chronology shows that from the late matuyama 1 77 ma the average half spreading rate was about 1 5 cm yr 1 with a slight decrease between the jaramillo and the brunhes events when the growth of the volcanic edifice overcame lateral spreading analysis of spreading rate and volume of erupted lava indicates that at the beginning of the jaramillo subchron 1 07 ma the marsili basin evolved from pure horizontal spreading to a superinflated seamount as a consequence of tearing of the ionian slab our data give us a snapshot of the geodynamic transition from an active backarc spreading phase to the vertical accretion of the seafloor because of a radical change in the subduction dynamics

morphotectonics of the carlsberg ridge between 62 20 and 66 20 e northwest indian ocean abstract the segmentation pattern of 440 km long section of the carlsberg ridge between 62 20 e and 66 20 e in the northwest indian ocean has been studied using multibeam bathymetry and magnetic data a well defined transform fault is the only first order discontinuity documented in this section of the ridge four segments have been identified based on the topographic fabric along axis depth variations and the presence of off axis traces of transform and non transform discontinuities these segments constitute four distinct domains representing magmatic and sparsely magmatic crustal accretion magnetic model studies show this section of the ridge is a slow spreading ridge with spreading half rates varying from 11 to 16 mm yr along axis variations in the magnetic anomalies and crustal magnetization the presence of axial volcanic ridges on the inner valley floor variations in the depth and geometry of the rift valley and recovery of mantle derived peridotites from the inner valley floor suggest distinct variations in the accretionary processes along the ridge it is suggested that the linear section in the east with ridge parallel topographic fabric continuous magnetic lineations and the segment with a shallow valley floor with along axis ridge propagation fabric represent a magmatic phase of crustal accretion the wide rift valley recovery of mantle rocks deformed topographic fabric along axis depth maxima and discontinuous magnetic lineations documented along the middle part of the ridge and the existence of short ridges east of the transform fault represent sparsely magmatic sections with dominance of tectonic extension

quantifying the recoverable resources of by product metals the case of cobalt abstract the long term availability of mineral resources is crucial in underpinning human society technology and economic activity and managing anthropogenic environmental impacts this availability is increasingly true for metals that do not generally form the primary product of mines such as copper or iron but instead are recovered as by products or sometimes co products during the processing of primary ores also known as companion metals e g indium cobalt molybdenum rhenium selenium these metals however can be of significant economic and technological importance both to a mine s economics and in downstream applications it is therefore useful to develop methodologies to estimate the recoverable resource for such companion metals i e the amount that could if desired be extracted and put into use over the next several decades monitoring the supply and demand of these resources is important to enable the identification of any changes that may have significant repercussions for the global economy technology needs and the environment here we derive an estimate of the recoverable resource for cobalt co a metal used with increasing frequency and in larger amounts in modern technology that is mainly recovered as a by product of copper and nickel ore processing and production co only mines are few in number and typically small in size our methodology combines the reported size of ore bodies that host co with measured or estimated co concentrations in the ores within these bodies the dominantly by product nature of co means that uncertainties exist for some of the co grades as well as recovery rates given this we also split our total recoverable co resource using a resource estimate data quality classification into high medium and low quality data depending on factors such as whether statutory resource reporting codes were used during resource reporting this methodology indicates that a minimum of 26 8 mt co is present in current global co resources with 15 2 5 6 and 6 0 mt co in high medium and low quality resources respectively applying typical recovery rates for different ore types indicates that 15 9 mt of this co is recoverable with 10 7 2 6 and 2 6 mt co recoverable in high medium and low quality resources respectively this approach provides a basis for determining similar recoverable resource estimates of other companion metals such as indium rhenium selenium etc all of which are of increasing importance in modern day life

sediment thicknesses of the western anatolia graben structures determined by 2d and 3d analysis using gravity data abstract western turkey is tectonically one of the most active and rapidly deforming regions of continental crust in the world the most pronounced structural and morphological features of this region are defined by normal faulting in an e w direction which creates the boundaries of the buyuk menderes kucuk menderes and gediz grabens the graben systems may have become active between 11 7 ma and are now deeper than the surrounding topography the gediz and buyuk menderes grabens exhibit negative bouguer gravity anomalies the bouguer gravity anomalies increase towards the center of the aegean sea in a regional sense the grabens are filled with recent sediments giving rise to relative negative gravity anomalies these anomalies were interpreted using 2d and 3d gravity inversion techniques in order to determine the depth to the metamorphic basement inversion of geophysical anomalies implies fitting the observed data to theoretical anomalies possibly produced by subsurface bodies inversion of gravity anomalies is a non linear problem in the sense that body parameters are not linearly related to the anomalies gravity anomalies caused by structures are mostly determined by a 2d model which has an n sided polygonal cross section for non linear problems theoretically it is more suitable to determine the parameters of the structure by a series of juxtaposing prisms or vertical dykes extending to infinity rather than using a single n side polygonal model the depths to the top surfaces of a rectangular prisms with infinite depth represent the relief of the basement the basement relief can be computed on the basis of density contrast if the reference depth is assessed as a result of 3d analysis of the bouguer gravity map the maximum thickness of sedimentary cover appears to be more than 2 0 and 1 5 km for the gediz and buyuk menderes grabens respectively towards the saraykoy kizildere area the sedimentary thickness cover thickens to more than 2 0 km 2d analysis of the bouguer gravity profiles indicate that the maximum thickness of the sedimentary cover is between 2 5 and 3 5 km in the buyuk menderes graben and between 0 5 and 2 0 km in the gediz graben

geochemistry of cobalt rich ferromanganese crusts from the perth abyssal plain e indian ocean abstract geochemistry of cobalt rich ferromanganese crusts from the as yet unexplored dirck hartog ridge dhr a linear bathymetric feature of poorly understood origin located in the centre of the perth abyssal plain pap is described for the first time based on 3 samples analyzed with xrf icp ms and epma mean bulk concentrations of fe and mn were 20 8 and 18 4 wt respectively individual crust layers however proved chemically variable the mean concentration of metals of the highest economic potential cu ni co was 0 69 wt the mean total rare earth elements ree and yttrium rey contents in the samples 1908 mg kg proved moderate the crusts showed strong positive ce anomalies negative y anomalies and a low y sn hosn ratio mean 0 56 observations on the texture and chemical composition of the crust samples studied allowed us to distinguish two major and two subtypes of representative colloform structures built of laminae the type i colloform structures showed the mn fe ratio to range from 0 86 to 5 69 the ranges in type ii colloform structures being 0 49 2 47 subtype ii 1 and 6 91 221 42 subtype ii 2 the subtype ii 2 colloform structures were enriched in ni up to 7 31 wt the co and cu concentrations showed a high variability 0 03 1 64 and 0 03 0 22 wt respectively according to the current genetic models and discrimination diagrams the crusts studied were classified as hydrogenetic although individual laminae and groups of laminae could be regarded as diagenetic or hydrothermal

critical metals in manganese nodules from the cook islands eez abundances and distributions abstract the cook islands cis exclusive economic zone eez encompasses 1 977 000 km2 and includes the penrhyn and samoa basins abyssal plains where manganese nodules flourish due to the availability of prolific nucleus material slow sedimentation rates and strong bottom currents a group of cis nodules was analyzed for mineralogical and chemical composition which include many critical metals not before analyzed for cis nodules these nodules have varying sizes and nuclei material however all are composed predominantly of mno2 and x ray amorphous iron oxyhydroxide the mineralogy fe mn ratios rare earth element contents and slow growth rates mean 1 9 mm 106 years reflect formation primarily by hydrogenetic precipitation the paucity of diagenetic input can be explained by low primary productivity at the surface and resultant low organic matter content in seafloor sediment producing oxic seafloor and sub seafloor environments the nodules contain high mean contents of co 0 41 ni 0 38 ti 1 20 and total rare earth elements plus yttrium rey 0 167 and also high contents of mo nb v w and zr compiled data from a series of four cruises by the japan international cooperation agency and the mining agency of japan from 1985 to 2000 were used to generate a map that defines the statistical distribution of nodule abundance throughout the eez except the manihiki plateau the abundance distribution map shows a belt of high nodule abundance 19 45 kg m2 that starts in the southeast corner of the eez runs northwest and also bifurcates into a sw trending branch small isolated areas contain abundances of nodules of up to 58 kg m2 six 20 000 km2 areas of particularly high abundance were chosen to represent potential exploration areas and maps for metal concentration were generated to visualize metal distribution and to extrapolate estimated metal tonnages within the six sites and the eez as a whole grades for mn cu and ni are low in cis nodules in areas of high abundance however ti co and rey show high contents where nodule abundances are high of the six areas identified to represent a range of metal contents one at the northern end of the n s abundance main belt optimizes the most metals and would yield the highest dry metric tons for mn 61 002 292 ni 1 247 834 mo 186 166 v 356 247 w 30 215 and zr 195 323 when compared with the clarion clipperton zone the cis nodules show higher nodule abundances 25 kg m2 over 123 844 km2 and are more enriched in the green tech high tech and energy metals co ti te nb rey pt and zr the cis eez shows a significant resource potential for these critical metals due to their high prices high demand and the high nodule abundance which will allow for a smaller footprint for a 20 year mine site and therefore smaller environmental impact

cobalt in ferromanganese crusts as a monitor of hydrothermal discharge on the pacific sea floor ferromanganese oxide crusts which accumulate on unsedimented surfaces in the open ocean1 6 derive most of their metal content from dissolved and particulate matter in ambient bottom water7 8 in proportions modified by the variable scavenging efficiency of the oxide phase for susceptible ions9 they differ in this respect from abyssal nodules much of whose metals are remobilized from host sediments here we present maps of cobalt concentration and inferred accumulation rate of ferromanganese crusts from the pacific ocean we propose that depletion of cobalt in pacific crusts measures the location and intensity of submarine hydrothermal discharge use of the cobalt chronometer an algorithm inversely relating cobalt content and crust growth rate permits mapping of the accumulation rate of ferromanganese crusts with only indirect recourse to radioactivity based dating methods these maps show that crusts in hydrothermal areas grow from two to more than four orders of magnitude faster than in the central pacific ocean cobalt enriched crusts are found where water masses are most isolated from continental coastal and hydrothermal sources of metals now and in the past this relationship can resolve the problem of cobalt enrichment in crusts without recourse to hypotheses invoking special cobalt sources or enrichment mechanisms

frequency dependent attenuation of coda waves in the crust in southwest anatolia turkey the attenuation of coda waves in the earth s crust in southwest sw anatolia is estimated by using the coda wave method which is based on the decrease of coda wave amplitude in time and distance a total of 159 earthquakes were recorded between 1997 and 2010 by 11 stations belonging to the koeri array the coda quality factor q c is determined from the properties of scattered coda waves in a heterogeneous medium firstly the quality factor q 0 the value of q c at 1 hz and its frequency dependency are determined from this method depending on the attenuation properties of scattered coda waves for frequencies of 1 5 3 0 6 0 8 0 12 and 20 hz secondly the attenuation coefficients are estimated the shape of the curve is controlled by the scattering and attenuation in the crustal volume sampled by the coda waves the average q c values vary from 110 15 to 1 436 202 for the frequencies above the q 0 and values vary from 63 7 to 95 10 and from 0 87 0 03 to 1 04 0 09 respectively for sw anatolia in this region the average coda q f relation is described by q c 78 9 f 0 98 0 07 and 0 012 km 1 the low q 0 and high are consistent with a region characterized by high tectonic activity the q c values were correlated with the tectonic pattern in sw anatolia

spreading history of the arabian sea some new constraints abstract based on a new identification of magnetic anomalies additional constraints are provided on the two episodes of spreading history of the arabian sea commencing at a27 the older phase ended at a21 and spreading of the younger phase started shortly before the formation of a11 the hiatus between these spreading episodes characterized by a magnetic quiet zone was much shorter 18 106 yr than previously believed after spreading restarted the younger phase continued at a very slow rate 0 7 cm yr till anomaly 6a this rate increased between anomalies 5c and 6a and the spreading continued to the present at about 1 2 cm yr the data also enabled identification of a new ne sw trending fracture zone which right laterally offsets the entire magnetic anomaly sequences 1 through 11 across the carlsberg ridge by about 50 km

fine scale study of major and trace elements in the fe mn nodules from the south china sea and their metallogenic constraints abstract many marine fe mn polymetallic nodules may contain high concentrations of mn cu ni zn co and rare earth elements plus yttrium rey to determine the occurrence and enrichment processes of these metals in the fe mn nodules we conducted high resolution mineralogical and geochemical studies on the fe mn nodules collected from the south china sea in situ epma and la icp ms analyses and elemental imaging were performed on individual microlayers of the nodules to reveal the major and trace element distributions the whole rock mineralogical and chemical compositions of the fe mn nodules indicate a hydrogenetic origin the mn mineral phases are mainly composed of nanocrystalline vernadite with interlayered 10 a and 7 a phyllomanganates such as todorokite birnessite and buserite fe ti oxides hydroxides are intergrown and essentially x ray amorphous feroxyhyte and goethite we recognize two main types of microlayers type a layer suboxic diagenetic precipitates containing a high mn fe ratio and high concentrations of cu ni zn ba li and mg and type b layer oxic hydrogenetic accretions with low fractionation of mn and fe and high contents of co rey ti sr and pb furthermore elemental mapping indicates that the enrichments of co and rey are mainly associated with fe mineral phases rather than mn ones which are enriched in mg cu ni zn li and ba two mineralization processes and metal distributions in the individual microlayers are identified in the fe or mn mineral phases the occurrence of 10 a and 7 a phyllomanganates in type a layers are commonly enriched in trace metals such as ni cu zn li ba and mg whereas the metals for the type b layers include co ti pb sr rey which may be carried by the intergrowing fe ti oxyhydroxides and vernadite thus hydrogenesis and diagenesis facilitate the enrichment of fe co ti sr pb rey and mn ni zn cu li ba mg respectively during the mineralization of the south china sea nodules

relation of alkaline volcanism and active tectonism within the evolution of the isparta angle sw turkey the isparta angle ia is formed along the boundary of the african and eurasian plates by ne and nw striking faults north of the antalya gulf in sw turkey the ne striking strike slip burdur fault bounds the ia to the west and is probably the continuation of the pliny system of the hellenic arc the nw striking aksehir fault bounds it to the east platform type parautochthonous mesozoic carbonate sequences such as the beydag and anamas akseki occur in the western and eastern parts of the ia respectively whereas allochthonous ophiolite nappes include the antalya beysehir hoyran and lycian nappes the ia and adjacent areas are divided into three areas the teke the antalya and the akseki fragments by ne nw and n striking active strike slip faults with normal components ia region volcanics are alkaline and hyperkaline in character potassic ultrapotassic and locally occur as subvolcanic stocks and dikes they can be traced between the afyon and isparta regions these volcanics consist mainly of

critical metal enrichment mechanism of deep sea hydrogenetic nodules insights from mineralogy and element mobility abstract the micro nano textural features major and trace element compositions of ferromanganese nodule from the marcus wake seamount group of the western pacific ocean were documented in this study the ferromanganese nodules genetically comprise a core and three types of layers the core is made up of porous quartz and locally fe mn oxides layer close to the core layer i mantle ii and rim iii are featured by a massive dense layer with stromatolite like structure laminated and detrital and dendritic rim respectively these layers contain mainly birnessite goethite and quartz the mn fe ratios 1 0 4 1 mean 1 9 demonstrate a hydrogenetic genesis for these nodules the nodules have moderate enrichments 1000 10 000 ppm of na mg al p k ti co ni and cu with minor enrichments 100 1000 ppm of v zn as sr y zr nb mo ba and pb whereas other elements li sc cr ge se rb sn cs hf w bi th and u have concentrations of several tens of ppm based on the growth rate calculated by co concentration layer i has the lowest mean growth rate 1 8 mm myr followed by layer ii 2 3 mm myr and then layer iii 2 7 mm myr integrating the previous marine nodule studies in the south china sea we suggest that the massive dense layers were possibly resulted from a slow growth rate the conduits of various scales may have promoted the post depositional processes as they enlarged the surface area for fluid dissolution and reprecipitation nickel enrichment is associated with birnessite and promoted by the post depositional processes as evidenced by the higher ni content in the early formed layer i and its decreasing trend from core to rim cobalt may have associated with mn3 and has less effect by post depositional accumulation the fe content which may have related to goethite fe3 o oh shows good correlations with the rey ree y contents this correlation demonstrates the scavenging of reys by hydrothermal fe oxyhydr oxides reys are likely released during the post deposition as the rey contents are decreasing from the core to rim and negatively correlated with the accumulation time the similarity of rey distribution pattern between hydrothermal nodule and goethite bearing and mn oxides free banded iron formation bif may suggest hydrothermal fe may have linked to rey enrichments in deep sea sediments these micro nano sized conduits are well developed in either type i ii or iii layer which likely served as fluid circulating conduits and facilitate post depositional processes