surface destabilisation by the invasive burrowing engineer mus musculus on a sub antarctic island abstract invasive species are known to have substantial trophic effects on ecosystems and ecosystem processes the invasion of the house mouse mus musculus onto sub antarctic islands has had a devastating effect on plants invertebrates and birds with substantial changes in ecosystem functions less well understood however are the nontrophic geomorphic effects of mice resulting from their burrowing activities we examined the extent of burrow construction by m musculus across an area of about 20 ha on marion island and the effects of burrows on water flow and sediment movement we recorded a density of 0 59 0 48 mean sd burrows m 2 with more burrows at lower altitudes and shallower slopes and twice the density in the solifluction risers 0 86 0 54 m 2 than the intervening terraces or treads 0 40 0 51 m 2 most burrows were dug horizontally into the slope and tended to extend about 20 cm deep before turning a very conservative estimate of sediment removed from burrows from this depth is 2 4 t ha 1 however taking into account more detailed data on burrow morphology based on excavations actual amounts may be closer to 8 4 t ha 1 average soil displacement rate for a single burrow measured over 5 days was 0 18 kg burrow 1 day 1 burrows acted as conduits for water and warmer air stones at burrow entrances were moved eight times farther by water 10 4 cm than those not associated with burrows similarly temperatures adjacent to burrow entrances were 4 1 c higher than sites 10 cm away together our data indicate that mice are having substantial deleterious and geomorphic effects on sub antarctic ecosystems through their burrowing with lower rates of mouse mortality resulting from warmer climates predicted under global climate models we can expect an increase in damage resulting from mouse activity

u pb and pb pb zircon ages for arc related intrusions of the bolu massif w pontides nw turkey evidence for late precambrian cadomian age we present new u pb and pb pb radiometric age data from two tectono stratigraphic units of the regionally extensive bolu massif in the w pontides fragment n turkey a structurally lower unit sunnice group is cut by small meta granitic intrusions whereas the structurally higher unit com prises meta volcanic rocks ca surtepe fm cut by meta granitic plutons tullukirisand kapokaya plutons u pb single crystal dating of zircons from the kapokaya pluton yielded a concordant cluster with a mean 238 u 206 pb age of 565 3 1 9 ma zircons from the tullukirispluton affected by pb loss gave a 207 pb 206 pb age of 576 6 ma age late precambrian small meta granitic intrusions cutting the sunnice group yielded a less precise 207 pb 206 pb age of 262 19 ma early permian the older ages from the bolu massif confirm the existence of latest precambrian arc magmatism related to subduction of a cadomian ocean we infer that the bolu massif represents a fragment of a cadomian active margin cadomian orogenic units were dispersed as exotic terranes throughout the variscan and tethyan orogens and the bolu massif probably reached its present position prior to latest palaeozoic time our dating results also confirm that nw turkey was affected by hercynian magmatism related to subduction of palaeotethys as inferred for other areas of the pontides

cosmogenic nuclides in the kirin chondrite abstract radioactive and stable cosmogenic nuclides have been determined in the various fragments of the kirin chondrite h5 experimental results obtained from our samples are described and compared with similar data obtained in other laboratories cosmogenic 54 mn 22 na 60 co 26 al 53 mn 40 k in the metal phase and light noble gases were measured based on these data the irradiation history of this meteorite can be explained in terms of 1 a multi stage exposure which involves a first stage irradiation for 10 7 years and a second stage for about 4 10 5 years and 2 depth effects in the productions of the nuclides in 4 second stage and 2 first stage geometries these conclusions are consistent with those of our previous work which was based on a limited number of samples

the south marmara fault we use about 800 km of multichannel exploration seismic reflection profiles of the seventies as well as the results of three drill holes that penetrated the sedimentary cover down to the upper cretaceous basement to describe a continuous gently curvilinear south concave zone of deformation about 10 km wide that extended over the whole southern shelf of the sea of marmara from the gulf of gemlik to the dardanelles straits in lower pliocene time about 4 ma we call this zone of deformation the south marmara fault smf system and propose that the smf was then a branch of the dextral north anatolian fault this branch passed to the north of the marmara island eocene block and thus had a south facing concavity this curvature resulted in a significant component of shortening in the western part of the fault the smf was deactivated at the end of lower pliocene about 3 5 ma except for its easternmost branch between the gulf of gemlik and imrali island where about 5 mm year of dextral motion is still occurring today

a late jurassic early cretaceous metamorphic core complex strandja massif nw turkey in the eastern part of the strandja massif constituting the east end of the rhodope massif the amphibolite facies basement rocks intruded by permian metagranites are juxtaposed against the greenschist facies cover metasediments of triassic middle jurassic protolith age the distinct metamorphic break between the basement and cover rocks requires a missing metamorphic section the boundary between the two groups of rocks is a ductile to brittle extensional shear zone with kinematic indicators exhibiting a top to the e ne shear sense footwall rocks are cut by weakly metamorphosed and foliated granite bodies which are clearly distinguished from the permian metagranites by their degree of deformation cross cutting relations and syn tectonic kinematic character also hangingwall rocks were intruded by unmetamorphosed and weakly foliated leucogranites 40ar 39ar data indicate that the ductile deformation from 156 5 to 143 2 ma middle oxfordian earliest berriasian developed during the syn tectonic plutonism in the footwall deformation and gradual slower cooling exhumation survived until to 123 ma barremian the mylonitic and brittle deformation in the detachment zone developed during oxfordian earliest berriasian time 155 7 142 6 ma and early valanginian aptian time 136 118 7 ma respectively our new field mapping and first 40ar 39ar ages demonstrate the existence of an extensional core complex of late jurassic early cretaceous age not previously described in the rhodope strandja massifs

turf banked terrace treads and risers turf exfoliation and possible relationships with advancing treeline fine scale geomorphic pedogenic processes at alpine treeline may facilitate the initial stages of conifer invasion of alpine tundra turf banked terraces and turf exfoliation associated with solifluction may provide both the topographic protection and the seedbed necessary for conifer establishment above treeline the morphometry stoniness and surface penetrability of turf banked terraces were recorded whereas differences among sites exist due to topographic constraints differences in soil penetrability depend on turf exfoliation exfoliated turf risers are significantly more penetrable than non exfoliated solifluction risers and adjacent treads these penetrable microsites provide favorable conditions for seed germination the process of turf exfoliation may play a role in conifer advance into tundra during climatic change d 2004 elsevier b v all rights reserved

constraints on north anatolian fault zone width in the crust and upper mantle from s wave teleseismic tomography we present high resolution s wave teleseismic tomography images of the western segment of the north anatolian fault nafz in turkey using teleseismic data recorded during the deployment period of the dana array the array comprised 66 stations with a nominal station spacing of 7 km thus permitting a horizontal and vertical resolution of approximately 15 km we use the current s wave results with previously published p wave teleseismic tomography to produce maps of relative vp vs anomalies which we use to highlight the difference in overall composition of the three terranes separated by the northern nnaf and southern snaf branches of the nafz our results show a narrow s wave low velocity anomaly beneath the northern branch of the nafz extending from the upper crust where it has a width of 10 km to the lower crust where it widens to 30 km this low velocity zone most likely extends into the upper mantle where we constrain its width to be 50 km and interpret it as indicative of localised shear beneath the nnaf this structure is similar to what has been observed for the nafz west of 32 and therefore we propose that the structure of the nnaf is similar to that of the nafz in the east the snaf does not show a very strong signature in our images and we conclude that it is most likely rooted in the crust possibly accommodating deformation related to rotation of the armutlu almacik blocks situated between the two nafz branches

direct observation of primary fluid inclusion formation observations of crystal growth in supersaturated kh 2 po 4 solutions indicate that it duplicates natural crystallization processes and formation of fluid inclusions in free liquids similar to vein formation or igneous systems continuous crystal growth by surface nucleation results in elongate fluid inclusions forndng as hollow tubes within kinked growth steps large flat fluid inclusions also form either by sealing of etch pits and other surface irregularities or along cracks propagated by crystal growth microscopic observation of real time crystal growth documents the formation of fluid inclusions along a surface or within a plane inclusions that would otherwise be identified as secondary these primary fluid inclusions resemble pseudosecondary inclusions or secondary necked down inclusions commonly observed in geologic samples furthermore these fluid inclusions and many or most in natural samples are not generated by spiral growth processes this simple analogue experiment serves as a model for crystal growth and fluid inclusion entrapment in hydrothermal and igneous systems

palaeozoic amalgamation of central europe new results from recent geological and geophysical investigations abstract multidisciplinary studies of geotransects across the north european plain and southern north sea and geological reexamination of the variscides of the north bohemian massif permit a new 3 d reassessment of the relationships between the principal crustal blocks abutting baltica along the trans european suture zone tesz accretion was in three stages cambrian accretion of the bruno silesian lysogory and malopolska terranes end ordovician early silurian accretion of avalonia and early carboniferous accretion of the armorican terrane assemblage ata palaeozoic plume influenced metabasite geochemistry in the bohemian massif explains the progressive rifting away of peri gondwanan crustal blocks before their accretion to baltica geophysical data faunal and provenance information from boreholes and dated small inliers and cores confirm that avalonian crust extends beyond the anglo brabant deformation belt eastwards to northwest poland the location and dip of reflectors along the tesz and beneath the north european plain suggest that avalonian crust overrode the baltica passive margin marked by a high velocity lower crustal layer on shallowly southwest dipping thrust planes forming the heligoland pomerania deformation belt the variscan orocline of southwest poland masks two junctions between the armorican terrane assemblage ata and previously accreted crustal blocks to the east is a dextrally transpressive contact with the bruno silesian and malopolska blocks accreted in the cambrian while to the north is a thrust contact with easternmost avalonia deeply buried beneath younger sedimentary cover in the northeast bohemian and rhenohercynian massifs devonian early variscide deformation dominated by wnw and nw directed thrusting records closure of ordovician devonian seaways between detached islands of the ata and avalonia

tectonics and magmatism in turkey and the surrounding area this volume contains 23 papers from a range of international contributors describing recent research into the tectonics and magmatism of turkey and its surroundings this region is sited at the collision zone between eurasia and afro arabia and as such provides an extraordinarily complete and well exposed record of the staged tectonic evolution of this sector of the alpine himalayan orogen the geological history of this area involves separation of continental fragments from the margin of gondwana their migration across the tethyan oceans the subsequent closure of these oceans and finally the development of the neotectonic regime which continues to evolve to the present day such a comprehensive record is relevant to the understanding of collisional zones worldwide the volume is divided into five sections tethyan evolution neotethyan ophiolites post tethyan basin evolution neotectonics and igneous activity the first two sections deal with tethyan oceans whose growth and subsequent closure dominated the geodynamic framework in the mesozoic and cenozoic the subsequent sections deal with more recent geological developments from the balkan peninsula in the west to the transcaucasus in the east that followed consumption of the tethyan oceans there is a broad mix of papers throughout the volume wide ranging review papers on ocean development and extensional tectonics are followed by detailed descriptions of petrology and geochemistry and geographically focused studies on basin evolution specific aspects of extensional and strike slip tectonics and discussions of the relationship of magmatic activity to the tectonic development of the area tectonics and magmatism in turkey and the surrounding area presents up to date results and ideas from a large number of international contributors on a wide range of current research activity in this region it is essential reading for all geoscientists with an interest in both academic and applied aspects of eastern mediterranean geology

aluminous granulites from the pulur complex ne turkey a case of partial melting efficient melt extraction and crystallisation abstract in the pulur complex ne turkey a heterogeneous rock sequence ranging from quartz rich mesocratic gneisses to silica and alkali deficient fe mg and al rich melanocratic rocks is characterized by granulite facies assemblages involving garnet cordierite sillimanite ilmenite spinel plagioclase quartz biotite corundum rutile and monazite textural evidence for partial melting in the aluminous granulites particularly leucosomes is largely absent or strongly obliterated by a late stage hydrothermal overprint however inclusion relations high peak p t conditions the refractory modes bulk and biotite compositions of the melanocratic rocks strongly support a model of partial melting the melt was almost completely removed from the melanocratic rocks and crystallised within the adjacent mesocratic gneisses which are silica rich bear evidence of former feldspar and show a large range in major element concentrations as well as a negative correlation of most elements with sio2 peak conditions are estimated to be 800 c and 0 7 0 8 gpa subsequent near isothermal decompression to 0 4 0 5 gpa at 800 730 c is suggested by the formation of cordierite coronas and cordierite spinel symplectites around garnet and in the matrix sm nd rb sr and 40ar 39ar isotope data indicate peak conditions at 330 ma and cooling below 300 c at 310 ma

the almacik mafic ultramafic complex exhumed sakarya subcrustal mantle adjacent to the istanbul zone nw turkey the almacik mountains in northwestern turkey expose an upper amphibolite facies complex consisting of alternating ultramafic harzburgitic and websteritic and mafic metagabbroic rock types in the eastern part of this complex are island arc meta tholeiites and transitional to calc alkaline metabasites that are chemically quite similar to those of the permo triassic cele mafic complex north of bolu and this suggests an equivalence however much of the section exposes structurally deeper and chemically different mafic and ultramafic rocks which have no equivalent in the cele mafic complex and isotopic dating has suggested that these rocks also formed during the permian period and underwent triassic and jurassic metamorphism furthermore sparse inherited ages unlike those from istanbul zone granitoids suggest a link with north african derived armorican type basement and hence the sakarya zone rather than amazonia derived avalonian basement alternating mafic and ultramafic rocks suggest structural repetition supported by the exposure of discrete high strain zones or poorly exposed shattered rock west of each outcrop of ultramafic rocks the high grade of metamorphism and the absence of either extrusive lavas or sheeted dyke rocks suggests that the almacik complex was not an ophiolite but formed instead as subcontinental lower crust and subjacent mantle dominantly calc alkaline geochemistry suggests that it formed the basement to an active continental margin bounding the north side of the sakarya continent with s dipping subduction of palaeotethys the almacik complex was uplifted as a late result of compression against the southern margin of the istanbul zone in the jurassic period lack of coeval high grade metamorphism in the istanbul zone indicates that the latter was overthrust southwards over the sakarya margin and that there was therefore a change of subduction polarity in the triassic period the evidence further casts doubt on the existence of a mesozoic intra pontide ocean in northwestern turkey and suggests that the latest permian magmatism with subsequent triassic and jurassic metamorphism was instead related to the closure of the palaeotethyan ocean

slope effect on saltation over a climbing sand dune abstract results from a three year study are presented that integrate field work in israel physical modeling wind tunnel testing at uc davis and numerical solutions of grain trajectories to model and explain sand transport over a climbing dune field grain size analyses of surface and saltation trap materials taken along various positions of the slope suggest that only smaller particles u equal 30 cm s were able to climb a 20 degree slope in an escarpment normal to the prevailing strong wind direction numerical solutions of the particle trajectories are in good agreement with field measurements and confirm that particle motion is diminished at the base area of the slope and that the motion of larger sized particles is completely terminated which causes an accumulation of these particles the results suggest that the transport of the majority of the larger particles 230 m is by saltation the model is numerically extended to a general series of slopes particle sizes and friction speeds with similar tends exhibited

re equilibration of primary fluid inclusions in peritectic garnet from metapelitic enclaves el hoyazo spain abstract primary appearing fluid fi and melt fi inclusions occur in peritectic garnet from restitic enclaves from el hoyazo spain the inclusions were trapped under conditions of immiscibility during partial melting of the enclaves trapped fluids in bt grt sil and spl crd enclaves have been characterized by microthermometric raman spectroscopic electron microprobe emp and transmission electron microprobe tem analyses to better constrain melt and fluid products and pressure conditions of the partial melting event in bt grt sil enclaves fi are one phase and contain a co2 n2 mixture sometimes with graphite as trapped phase in spl crd enclaves fi are two phase and contain an h2o rich 90 mol with minor amounts of co2 n2 and traces of h2s and ch4 graphite often occurs as a trapped phase in the h2o rich fi and rare carbonates and other accessory minerals are also observed although decrepitation features are not recognized during examination with a petrographic microscope fi densities based on mass balance constraints are always lower than expected at the inferred pt conditions of entrapment 5 7 kbar and 800 900 c extremely low densities 0 1 g cm 1 of fi in bt grt sil enclaves suggest a pressure 500 bar at 800 900 c while densities up to 0 53 g cm 1 in spl crd enclaves indicate p 3 kbar at 800 900 c re equilibration is likely to have occurred via partial decrepitation as suggested by tem studies that show rare partially annealed sub m cracks containing small cavities which may have been the pathways for fluid movement out of the inclusions mi coexisting with fi have a rhyolitic peraluminous composition with higher h2o contents of mi in spl crd enclaves 9 wt compared to mi in bt grt sil enclaves 3 wt based on published data peritectic garnet in spl crd enclaves grew in the presence of a leucogranitic melt saturated in an h2o rich fluid in good agreement with the inferred garnet pt growth conditions the composition of the fluid phase coexisting with melt in bt grt sil enclaves cannot be evaluated owing to the almost complete decrepitation and fluid loss from fi and may only be inferred to have been more co2 rich based on the lower h2o content of the coexisting melt

geological evolution of the late mesozoic continental margin of northwestern anatolia abstract the armutlu peninsula is a composite tectonic entity made up of sections of the sakarya continent the rhodope pontide fragment and an ophiolite these were assembled following a continental collision between gondwanaland and laurasia during the late cretaceous the northern margin of the sakarya continent underwent progressively increasing deformation prior to and during the advancing collision due to continued convergence between the two continents initially the leading edge of the continent subsided under the load of an approaching ophiolitic slab following this a north directed thrusting and folding occurred during the turonian progressive elimination and eventual closure of the ocean preceded the thrusting of northerly situated collisiondashinduced nappe packages over the leading edge of the sakarya continent the nappe laden edge of the continental margin then collapsed and steadily subsided under the heavy load of the ophiolitic slab and the northern continental fragment consequently the nappe packages and the ophiolite were collectively metamorphosed during the coniaciandashsantonian interval during the subsidence the main body of the sakarya continent partially detached from its collapsed edge along a fault zone and thus suffered an independent but less severe deformation which lasted until the uplift of the collapsed edge in the campanian from the late campanian onward throughout later orogenic stages the metamorphic and nondashmetamorphic units amalgamated into a single tectonic entity forming a basement for younger cover rocks

evidence for a minimum 52 1 km of total offset along the northern branch of the north anatolian fault in northwest turkey abstract the north anatolian fault naf splits into two major branches in northwestern turkey with most of the present strain accumulation and holocene displacement being along the northern branch naf n estimates of total offset along the naf n range between 4 km and 70 km in the marmara sea region these different estimates lead to different interpretations on the formation of marmara sea basins in this study we use cretaceous faults sub perpendicular to the naf n as precise offset markers based on these faults as well as the offset of the middle eocene volcanic belt we report a minimum 52 1 km cumulative dextral displacement along the naf n east of marmara sea near 31 e longitude the displacement of the middle eocene volcanic belt shows that the offset is post middle eocene if we assume an additional 15 km dextral displacement on the second strand of the naf n duzce fault the total offset along the naf n can be estimated as 67 km in the eastern marmara region adding the published offsets that range from 16 to 26 km on the southern branch of the naf give a total offset estimate of whole naf zone as 88 5 km in the eastern marmara region the gps velocity estimate indicates 23 mm yr 1 of total plate motion across and near eastern marmara sea that would take 3 9 million years to accumulate 88 km of displacement on the naf additionally the anatolian plate would not have instantaneously accelerated to its modern rate of motion thus initiation of transform displacement must somewhat pre date 3 9 ma

magmatic immiscibility and fluid phase evolution in the mount genis granite southeastern sardinia italy the mount genis granite is one of the post tectonic intrusives emplaced late in the magmatic history of the hercynian batholith in sardinia devitrified silicate melt inclusions are present in some magmatic rock forming and miarolitic quartz these magmatic remnants show initial melting at 680 720 c high temperature observations 700 800 c revealed the presence in some of the inclusions of mixed hydrosaline melt l1 and silicate melt l2 with extremely variable l1l2 ratios electron microprobe analyses indicate l1 to be k na dominated chlorides inclusions of mixed silicate and hydrosaline melts are interpreted to have been formed by heterogeneous trapping of two immiscible fluid phases silicate hydrosaline after second boiling most likely during the final crystallization stage magma derived brines 63 eq wt nacl circulated at subsolidus conditions from 600 c and were retained in the miarolitic cavities down to about 400 c fluid unmixing occurred locally in the miarolitic cavities from 550 to 412 c at temperatures of 400 to 100 c the microgranite was invaded by diluted waters 4 5 eq wt nacl a possible model for fluid evolution begins with a hydrosaline melt exsolving from the magma at the late magmatic stage the absence of boiling within the volatile hydrosaline system shows that brines can occur by direct magmatic immiscibility the comprehensive hydrothermal evolution suggests a nearly isobaric cooling path with local boiling episodes in the miaroles probably in coincidence with invasion of external waters

cordierite gneisses of southern kerala india petrology fluid inclusions and implications for crustal uplift history the cordierite bearing gneisses occurring as elongate patches in an 8 to 10 km wide zone along the achankovil fault lineament at the northern margin of the southern kerala crustal segment represent an important lithological unit in the archaean granulite terrane of south india the textural relationships in these rocks are consistent with the following main reactions 1 garnet quartz cordierite hypersthene 2 garnet sillimanite quartz cordierite 3 hypersthene sillimanite quartz cordierite 4 sillimanite spinel cordierite corundum and 5 biotite quartz sillimanite cordierite k feldspar many of the mineral associations and reaction textures including the remarkable preservation of symplectites are indicative of partial replacement of high pressure assemblages by cordierite bearing lower pressure ones during an event of rapid decompression temperature estimates from coexisting mineral phases show 710 garnet biotite 791 garnet cordierite and 788 c garnet orthopyroxene pressure estimates from mineral assemblages range from 5 4 to 7 kb detailed fluid inclusion studies in quartz associated with cordierite show high density co2 0 80 0 95 g cm3 as the dominant fluid phase with traces of probable ch4 in the sillimanite bearing rocks the isochore for the higher density fluid inclusions defines a pressure of 5 5 kb the fracture bound co2 and co2 h2o ch4 inclusions indicate simultaneous entrapment at 400 c and 1 7 kb in the cordierite hypersthene assemblage and 340 c and 1 2 kb in the cordierite sillimanite assemblage the p t path delineated from combined solid and fluid data corresponds to the piezothermic array of the gneisses and is characterized by t convex nature indicative of rapid and virtually isothermal crustal uplift probably aided by extensional tectonics

metamorphism and diachronous cooling in a contractional orogen the strandja massif nw turkey the southern part of the strandja massif northern thrace turkey comprises a basement of various gneisses micaschists and rare amphibolite and a cover of metaconglomerate and metasandstone separated from each other by a pre metamorphic unconformity metamorphic grade decreases from the epidote amphibolite facies in the south to the albite epidote amphibolite greenschist facies transition in the north estimated p t conditions are 485 530 c and 0 60 0 80 gpa in the epidote amphibolite facies domain and decrease towards the transitional domain between greenschist and epidote amphibolite facies rb sr muscovite ages range from 162 9 1 6 ma to 149 1 2 1 ma and are significantly older 279 296 ma in the northernmost part of the study area the rb sr biotite ages decrease from 153 9 1 5 ma in the south to 134 4 1 3 ma in the north these age values in conjunction with the attained temperatures suggest that the peak metamorphism occurred at around 160 ma and cooling happened diachronously and rb sr muscovite ages were not reset during the metamorphism in the northernmost part structural features such as i consistent s dipping foliation and sw to se plunging stretching lineation ii top to the n shear sense and iii n vergent ductile shear zones and brittle thrusts suggest a n vergent compressional deformation coupled with exhumation we tentatively ascribe this metamorphism and subsequent diachronous cooling to the northward propagation of a thrust slice the compressional events in the strandja massif were most probably related to the coeval n vergent subduction collision system in the southerly lying rhodope massif

a multi proxy analysis of late quaternary palaeoenvironments sekhokong range eastern lesotho the eastern lesotho highlands host an array of periglacial and glacial geomorphic features their analysis has provided past climate interpretations predominantly for cold periods yet no multi proxy temporally continuous palaeoenvironmental records exist this study presents a palaeoenvironmental reconstruction based on sedimentary characteristics fossil pollen and diatoms from an alpine wetland located in the sekhokong mountain range the record commences in the late pleistocene with a wet period from 16 450 to 14 440 cal a bp interrupted by dry conditions from 16 350 to 15 870 cal a bp from 14 150 to 8560 cal a bp drier conditions are inferred slowly transitioning to warmer wetter conditions warmer dry conditions are inferred for 8560 7430 cal a bp followed by cold wet conditions from 7280 to 6560 cal a bp a dry warmer period occurs from 6560 to 3640 cal a bp indicated by pollen diatom and sedimentary records followed by cool wet conditions from 3400 to 1200 cal a bp the period from 1110 cal a bp to the present is characterized by progressive drying pronounced cold events are detected from the diatom record moisture records appear relatively specific to the topographic setting of sekhokong near the great escarpment edge probably driven by orographically constrained synoptic controls

the cele mafic complex evidence for triassic collision between the sakarya and istanbul zones nw turkey abstract the lowest structural levels of the istanbul zone are exposed in the sunnice massif north of bolu they comprise the greenschist facies ediacaran calc alkaline bimodal yellice metavolcanics which are intruded by the dirgine granitoid amphibolite facies mafic and subordinate ultramafic rocks of the cele mafic complex hitherto termed the cele meta ophiolite include hornblende gneisses of island arc meta tholeiitic and transitional to calc alkaline metagabbroic compositions and were previously thought to be part of the istanbul zone basement together with minor serpentinized troctolite and harzburgite lenses they are exposed in a broadly antiformal structure beneath the yellice metavolcanics although these rocks structurally underlie and on account of their higher metamorphic grade were previously thought to be older than the ediacaran cambrian rocks of the istanbul zone basement their oldest isotopic dates are permian indicating that they are instead much younger than the overlying rocks from which they must be divided by an inferred istanbul zone basal thrust instead these mafic rocks may be linked to the almacik complex and hence interpreted as the underthrust crustal base to a permo triassic active continental margin attached to the gondwana derived sakarya zone now located south of the istanbul zone triassic and jurassic metamorphic ages record compressional events marking a cimmerian event closing the palaeotethys ocean

annually re forming miniature sorted patterned ground in the high drakensberg southern africa an analysis of miniature sorted circles and polygons provides the first detailed assessment of sorted patterned ground from a southern african alpine region pattern dimensions and particle sorting were determined from two sites in the high drakensberg although the sorted patterns in the high drakensberg are somewhat polygenetic in developmental origin they are primarily frost induced miniature sorted patterned ground below 3200 m a s l on the drakensberg plateau develops annually during the winter months and disintegrates towards summer the development of miniature sorted patterns within five to six weeks demonstrates the effect of regular freeze thaw cycles at higher altitudes in the drakensberg 1997 by john wiley sons ltd

late palaeozoic marginal basin and subduction accretion the palaeotethyan kure complex central pontides northern turkey the kure complex located in the central pontides of northern turkey is a c 20 km thick pile of thrust imbricated deep sea sediments intercalated with a dismembered ophiolite the ophiolitic rocks include serpentinized harzburgite massive gabbro cumulate and isotropic sheeted dykes and basic volcanic rocks the extrusive rocks are mainly pillow lavas sheet flows and lava breccias geochemical evidence of immobile major and trace elements and pyroxene chemistry indicate mid ocean ridge mor and volcanic arc basalt vab compositions and suggest that the kure ophiolite was generated above a subduction zone chrome spine1 analysis also supports this interpretation in some thrust sheets the extrusives are depositionally overlain by hemi pelagic shales passing up into terrigenous turbidites and shales which are up to several hundred metres thick in intact successions cyprus type massive sulphides interpreted as precipitates from black smokers are located along the lava sediment contact individual intact sediment units up to several kilometres thick within the kure complex are separated by narrow up to 10 m wide zones of intense shearing layer parallel extension and melange formation asymmetrical folds reverse faults thrusts and duplex structures throughout the kure complex indicate mainly northwards emplacement the kure complex is thought to have opened in the late palaeozoic as a marginal basin above a northward dipping palaeotethyan subduction zone located along the southern margin of eurasia the kure marginal basin later closed in response to inferred southward subduction leading to development of an accretionary prism prior to late jurassic time the kure complex is unlikely to represent the main palaeotethyan suture as has been suggested in some earlier tectonic reconstructions regional comparisons with dobrogea crimea and caucasus suggest the kure basin opened then closed along a south eurasia active margin

microstructures of melt inclusions in anatectic metasedimentary rocks the occurrence of crystallized and glassy melt inclusions mi in high grade partially melted metapelites and metagraywackes has opened up new possibilities to investigate anatectic processes the present study focuses on three case studies khondalites from the kerala khondalite belt india the ronda migmatites spain and the barun gneiss nepal himalaya the results of a detailed microstructural investigation are reported along with some new microchemical data on the bulk composition of mi these inclusions were trapped within peritectic garnet and ilmenite during crystal growth and are therefore primary inclusions they are generally isometric and very small in size mostly 15 m and only rarely reaching 30 m they occur in clusters in most cases inclusions are crystallized nanogranites and contain a granitic phase assemblage with quartz feldspar and one or two mica depending on the particular case study commonly with accessory phases mainly zircon apatite rutile in many cases the polycrystalline aggregates that make up the nanogranites show igneous microstructures e g granophyric intergrowths micrographic quartz in k feldspar and cuneiform rods of quartz in plagioclase further evidence for the former presence of melt within the investigated inclusions consists of melt pseudomorphs similar to those recognized at larger scale in the host migmatites moreover partially crystallized inclusions are locally abundant and together with very small 8 m glassy inclusions may occur in the same clusters both crystallized and partially crystallized inclusions often display a diffuse nanoporosity which may contain fluids depending on the case study after entrapment inclusions underwent limited microstructural modifications such as shape maturation local necking down processes and decrepitation mainly in the barun gneiss which did not influence their bulk composition re homogenized nanogranites and glassy inclusions show a leucogranitic and peraluminous composition consistent with the results of partial melting experiments on metapelites and metagraywackes anatectic mi should therefore be considered as a new and important opportunity to understand the partial melting processes

a fore arc origin for the thrace basin nw turkey hydrocarbon bearing thrace basin occupies much of the european part of turkey the middle eocene to oligocene sequence in the centre of the basin exceeds 9 km in thickness based on the stratigraphy structure and the regional context of this basin we propose that it developed as a fore arc basin between the medial eocene and the oligocene above the northward subducting intra pontide ocean its post miocene history has been dominated mainly by wrench tectonics resulting from the activity of the now deactivated northwestern strand of the present day north anatolian fault zone

kastamonu granitoid belt of northern turkey first arc plutonism product related to the subduction of the paleo tethys many granitoid plutons of middle jurassic age arc plutonic in character form a belt to the north of the paleo tethyan suture zone in northern anatolia these plutons are here called the kastamonu granitoid belt when they are interpreted in a regional geologic setting it can be shown that they may be formed by the magmatism related to the northward subduction of paleo tethyan oceanic crust

uranium lead isotopic ages of the samail ophiolite oman with applications to tethyan ocean ridge tectonics plagiogranites are a minor but widespread component of the samail ophiolite plutonic member they crystallized from the most fractionated melts generated by magmatic crystallization and differentiation of a steady state magma chamber beneath the tethyan spreading ocean ridge and their ages are thought to mark the time of ocean crust formation isotopic u pb ages of zircons from 13 plagiogranites collected along a 270 km segment of the samail ophiolite subparallel to the regional trend of the sheeted dike complex the former spreading ridge axis direction define a narrow time interval of 93 5 97 9 m y with a pronounced clustering about 95 m y the zircon ages of the plagiogranites agree remarkably well with the early cenomanian to early turonian biostratigraphic ages of sediments that are intercalated within the ophiolite pillow lavas and that lie just above them tippit et al 1981 the agreement of radiometric and biostratigraphic ages provides strong support for the conclusion that the plagiogranite u pb ages closely date the time span of ocean crust formation no step changes in age patterns are observed along the ridge axis sheeted dike direction suggesting that there are no major internal offsets of the ophiolite by transform or other faults along most of the traverse one possible exception occurs at the southeastern end of the sampled interval ibra area where a 3 m y discontinuity might be caused by an unmapped fault assuming that the regional trend of the sheeted dikes n10 25 w marks the direction of the former spreading ridge axis the present array of sample localities spans a distance of 130 to 195 km normal to that axis i e in the spreading direction the data as a whole do not define a clear cut age trend normal to the spreading axis but by eliminating samples that may be aberrant due to faulting the data array suggests a pattern of increasing ages from east to west this would indicate that the samail ophiolite is derived from the western southwestern side of the tethyan spreading system a conclusion reached independently from geological evidence also the gentle age gradient in the spreading direction i e between 130 and 195 km of ocean crust were formed within an age span of no more than 2 m y suggests a very fast spreading rate this conclusion also is supported by independent geologic evidence

alpine turf exfoliation pans in lesotho southern africa climate process morphological linkages abstract although alpine pans have been reported from a variety of mountain regions these have received limited research attention and are thus amongst the least known of closed basins this study investigates macro and fine scale morphological attributes and the process dynamics of alpine turf exfoliation pans in the high drakensberg of lesotho southern africa climate data temperature precipitation and wind are used to better ascertain climate surface process linkages and how these may be associated with the observed morphological phenomena thirty pans were assessed for both macro and fine scale aspect controlled morphological attributes during 2005 tinytag temperature loggers recorded ground temperatures on various pan riser aspects to establish the potential for cryogenic activity similarly wind speed and direction data from 2001 were used to identify the potential role of wind as an erosion and transportation mechanism the number and total weight of detached turf clumps accumulated at the base of various pan riser aspects were determined in july 1999 september 2001 and september 2004 it is suggested that the pans originated through initial turf disruption by animal trampling and turf burning followed by the cryogenic up heave of sediments the pans typically elongate towards the southeast as they enlarge demonstrate most active erosion on eastern and southeastern riser aspects and host seasonal micro echo and micro climbing dunes along such riser aspects it is concluded that an annual cyclic seasonal pattern of contemporary climate driven geomorphic processes dominated by strong northwesterly winds control the fine scale morphological evolution of alpine turf exfoliation pans in the lesotho highlands

late quaternary environmental change in central southern africa new data synthesis issues and prospects much of the interior of central southern africa is a sand sea within which aeolian and lacustrine landforms and sediments of local and regional extent are preserved closed cave sites are restricted to very few locations while fluvial systems traverse the margins of the interior until the early 1990s chronologies of late quaternary environmental and climatic changes developed for this region were based on only a limited number of proxy data sets derived largely from lacustrine deposits and precipitates in particular directly determined ages from aeolian deposits the most extensive suite of features in the region were absent the application of luminescence dating techniques to dune sediments and the development of further detailed chronologies from cave precipitates is now providing a more comprehensive record for the last 50 ka with some chronologies extending back a further 100 ka we present and review these data assess their contribution to enhanced understanding of late quaternary environmental changes in the region and for the first time assess them against corrected radiocarbon ages from lacustrine sites it is concluded that there is now an enhanced understanding of the spatial and temporal complexity of climate changes affecting the region in the last glacial cycle including a complex record of punctuated aridity but that many issues including data set integration and forcing mechanism controls are imperfectly understood

ophiolite emplacement by strike slip tectonics between the pontide zone and the sakarya zone in northwestern anatolia turkey northwestern anatolia contains three main tectonic units a the pontide zone in the north which consists mainly of the istanbul zonguldak unit in the west and the ballidag kure unit in the east b the sakarya zone or continent in the south which is juxtaposed against the pontide zone due to the closure of paleo tethys prior to late jurassic time and c the armutlu ovacik zone which appears to represent a tectonic mixture of both zones these three major tectonic zones are presently bounded by the two branches of the north anatolian transform fault the two tectonic contacts follow older tectonic lineaments the western pontide fault which formed during the development of the armutlu ovacik zone since the earliest cretaceous an overall extensional regime dominated the region a transpressional tectonic regime of coniacian santonian to campanian age caused the welding of the istanbul zonguldak unit to the sakarya zone by an oblique collision in the late campanian a transtensional tectonic regime developed forming a new basin within the amalgamated tectonic mosaic the different tectonic regimes in the region were caused by activity of the western pontide fault most of the ophiolites within the armutlu ovacik zone belong to the paleo tethyan and or pre ordovician ophiolitic core of the istanbul zonguldak unit the late cretaceous ophiolites in the eastern parts of the armutlu ovacik zone were transported from neo tethyan ophiolites farther east by left lateral strike slip faults along the western pontide fault there is insufficient evidence to indicate the presence of an ocean intra pontide ocean between the istanbul zonguldak unit and the sakarya zone during late cretaceous time

a new classification of the turkish terranes and sutures and its implication for the paleotectonic history of the region abstract the turkish part of the tethyan realm is represented by a series of terranes juxtaposed through alpine convergent movements and separated by complex suture zones different terranes can be defined and characterized by their dominant geological background the pontides domain represents a segment of the former active margin of eurasia where back arc basins opened in the triassic and separated the sakarya terrane from neighbouring regions sakarya was re accreted to laurasia through the balkanic mid cretaceous orogenic event that also affected the rhodope and strandja zones the whole region from the balkans to the caucasus was then affected by a reversal of subduction and creation of a late cretaceous arc before collision with the anatolian domain in the eocene if the anatolian terrane underwent an evolution similar to sakarya during the late paleozoic and early triassic times both terranes had a diverging history during and after the eo cimmerian collision north of sakarya the kure back arc was closed during the jurassic whereas north of the anatolian domain the back arc type oceans did not close before the late cretaceous during the cretaceous both domains were affected by ophiolite obduction but in very different ways north directed diachronous middle to late cretaceous melange obduction on the jurassic sakarya passive margin senonian synchronous southward obduction on the triassic passive margin of anatolia from this it appears that the izmir ankara suture currently separating both terranes is composite and that the passive margin of sakarya is not the conjugate margin of anatolia to the south the cimmerian taurus domain together with the beydaglari domain part of the larger greater apulian terrane were detached from north gondwana in the permian during the opening of the neotethys east mediterranean basin the drifting cimmerian blocks entered into a soft collision with the anatolian and related terranes in the eo cimmerian orogenic phase late triassic thus suturing the paleotethys at that time the taurus plate developed foreland type basins filled with flysch molasse deposits that locally overstepped the lower plate taurus terrane and were deposited in the opening neotethys to the south these olistostromal deposits are characterized by pelagic carboniferous and permian material from the paleotethys suture zone found in the mersin melange the latter as well as the antalya and mamonia domains are represented by a series of exotic units now found south of the main taurus range part of the mersin exotic material was clearly derived from the former north anatolian passive margin huglu type series and re displaced during the paleogene this led us to propose a plate tectonic model where the anatolian ophiolitic front is linked up with the samail baer bassit obduction front found along the arabian margin the obduction front was indented by the anatolian promontory whose eastern end was partially subducted continued slab roll back of the neotethys allowed anatolian exotics to continue their course southwestward until their emplacement along the taurus southern margin mersin and up to the beydaglari promontory antaya mamonia in the latest cretaceous paleocene the supra subduction ocean opening at the back of the obduction front troodos type ocean was finally closed by eocene north south shortening between africa and eurasia this brought close to each other cretaceous ophiolites derived from the north of anatolia and those obducted on the arabian promontory the latter were sealed by a maastrichtian platform and locally never affected by alpine tectonism whereas those located on the eastern anatolian plate are strongly deformed and metamorphosed and affected by eocene arc magmatism these observations help to reconstruct the larger frame of the central tethyan realm geodynamic evolution

pre early ordovician cadomian arc type granitoids the bolu massif west pontides northern turkey geochemical evidence the west pontides tectonic belt of northern turkey comprises a lower ordovician lower carboniferous transgressive sequence a stratigraphic basement to this paleozoic sequence is exposed in the bolu area the tectono stratigraphy of the basement closely resemble that of the cadomian belt of western europe three rock units forming the basement imply development of an andean type active continental margin during the pre early ordovician period high grade metamorphics the sunnice group granitoids the bolu granitoid complex and evolved felsic meta volcanic rocks the casurtepe formation are exposed unconformably beneath the lower ordovician fluvial clastics between the bolu yedigoller area to the north of bolu the bolu granitoid complex comprises a group of intrusive rocks of variable composition and size generated through multiple episodes of magmatism and is represented by two separate intrusive bodies within the study area the tullukiris pluton in the west and the kapikaya pluton in the east both plutons are mainly tonalite and granodiorite in composition more felsic and mafic compositional varieties also occur major and trace element chemical characteristics of the granitoids as well as biotite chemistry indicate that these are volcanic arc type granitoids and are products of an immature arc developed during early stages of a subduction furthermore textural and chemical characteristics of the plutons show that these are subvolcanic intrusions emplaced at shallow depths and are calc alkaline in composition the granitoidic plutons intrude the casurtepe formation the casurtepe formation is represented by arc type volcanics and volcaniclastics both the casurtepe formation and the granitoids represent subduction zone magmatism constructed on a continental crust represented by the sunnice group the history is very similar to cadomian active margins as exposed in western europe i e the north armorican and bohemia massifs and therefore the basement to the paleozoic of the west pontides is considered to be a preserved remnant of the cadomian belt

soil crusting on sandy soils and its influence on wind erosion abstract under rainfall a crust forms at the surface of most soils for soils rich enough in clay clay content 5 it is well known that a physical crust is responsible for a supply limitation of particles available for wind erosion sandy soils are very prone to crusting as well as to wind erosion indeed structural sieving crusts develop on sandy soils even after light rainfalls this kind of crust shows a loose sand layer at the surface overlying a thin layer where fine particles are concentrated the main objectives of this study were to determine whether such a crust formation limits the availability of 1 sand grains for entrainment into saltation and 2 fine particles for uptake into a vertical wind erosion flux suspension in atmosphere of particles

proterozoic ophiolites and mafic ultramafic complexes marginal to the istanbul block an exotic terrane of avalonian affinity in nw turkey abstract among the proterozoic inliers in the istanbul block the lowest structural levels are exposed in the sunnice massif north of bolu amphibolite facies mafic and subordinate ultramafic rocks of the cele meta ophiolite underlie the greenschist facies ediacaran calc alkaline yellice metavolcanics which are intruded by the 565 576 ma dirgine granitoids hornblende gneisses of the cele meta ophiolite comprise island arc meta tholeiites and transitional to calc alkaline metabasalts which together with minor serpentinite are disposed in a broadly antiformal structure the meta ophiolitic rocks are therefore the oldest ophiolites in nw turkey and are themselves thrust on to a putative pre existing continental margin now represented by the metasedimentary migmatites of the demirci gneisses which may thus be the oldest rocks of the complex the istanbul block is an exotic terrane unlike other western turkish terranes it lacks variscan metamorphism its different provenance indicated by its geological record faunal affinities and inherited mid proterozoic isotopic dates suggests a former link with avalonian basement in england nw europe and the maritime provinces of canada hence together with other terranes now situated further east than the avalonian terranes of nw europe the istanbul block may represent the easternmost extremities of avalonia which were detached during its end ordovician collision with the bruno silesian promontory on the sw margin of baltica subsequent migration of the istanbul block to its present location occurred by eastward displacement by sinistral transpression along the southern margin of baltica to a point east of the dobrogea and south of the scythian platform followed by collision with the sakarya block in the mesozoic and late cretaceous southward displacement with the opening of the black sea basin

geochemical characteristics of the adakite like dodurga pluton central pontides n turkey implications for middle triassic continental arc magmatism in southern black sea region the tracing of triassic arc magmatism is much debated for a long time along the sakarya composite terrane in turkey and the southern black sea region the dodurga pluton is located in the central pontides n turkey one of the most complicated regions around the black sea region and represents the first documented middle triassic continental arc in the region this pluton comprises of dacite porphyry and granodiorite and displays calc alkaline signatures which is in agreement with arc related and i type magmas the pm normalized multi element and cn normalized ree patterns are akin to volcanic arc granites and characterized by liles and lrees enrichments relative to hfses and hrees coupled with negative nb anomalies which confirm derivation in a subduction related tectonic setting moreover the major and trace element systematics of the samples including higher sr y ratios 22 93 101 36 and lower yb contents 0 31 1 30 ppm are consistent with those from adakitic melts compared to classical arc magmas therefore this pluton also represents the first middle triassic adakite like magmatic occurrence in turkey overall petrographic and geochemical signatures reported here indicate that the dodurga pluton might have been derived from a heterogeneous source mixed by melts from subducted oceanic slab and lower continental crust in an active continental margin based on the tethyan evolution in the anatolian realm three geodynamic scenarios are possible for its formation and it could have been formed as a result of northward or southward subduction of the paleotethys ocean or northward subduction of the northern branch of neotethys ocean during the middle triassic

the tectonics of the strandja massif late variscan and mid mesozoic deformation and metamorphism in the northern aegean the strandja massif is a mid mesozoic orogenic belt in the balkans build on a late variscan basement of gneisses migmatites and granites new single zircon evaporation ages from the gneisses and granites indicate that the high grade metamorphism and plutonism is early permian in age 271 ma the late variscan basement was unconformably overlain by a continental to shallow marine sequence of early triassic mid jurassic age during the late jurassic early cretaceous oxfordian barremian the lower mesozoic cover and the basement were penetratively deformed and regionally metamorphosed in greenschist facies possibly due to a continental collision an rb sr biotite whole rock age from a metagranite dates the regional metamorphism as late jurassic 155 ma deformation involved north vergent thrust imbrication of the basement and the emplacement of allochthonous deep marine triassic series over the jurassic metasediments the metamorphic rocks of the strandja massif are unconformably overlain by the cenomanian shallow marine sandstones during the senonian the northern half of the strandja massif formed a basement to an intra arc basin and to a magmatic arc generated above the northward subducting tethyan oceanic lithosphere the srednogorie arc closed during the early tertiary through renewed northward thrusting of the strandja massif

the ordovician volcanics of the elmtree belledune inlier and their relationship to volcanics of the northern miramichi highlands new brunswick an investigation of the geology and chemistry of the basic igneous rocks in the elmtree and belledune inliers in northern new brunswick shows that the bulk of the middle ordovician rocks of the ophiolitic fournier group are best interpreted as the products of volcanism and sedimentation in an extensive ensimatic back arc basin southeast of a volcanic arc the oceanic back arc basin igneous rocks form the basement to renewed arc related basaltic volcanism in late middle to late ordovician time the fournier group is separated from the structurally underlying shale dominated elmtree formation of the tetagouche group by an extensive tectonic melange which incorporates lenses of serpentinite mafic volcanic rocks and sedimentary rocks of both the tetagouche and fournier groups the mafic volcanic rocks in the elmtree formation correlate best with those intercalated with the lithologically similar sediments of the llandeilian caradocian boucher brook formation in the northern miramichi highlands the melang

a parameterisation for the threshold shear velocity to initiate deflation of dry and wet sediment abstract a new parameterisation for the threshold shear velocity to initiate deflation of dry and wet particles is presented it is based on the balance of moments acting on particles at the instant of particle motion the model hence includes a term for the aerodynamic forces including the drag force the lift force and the aerodynamic moment force and a term for the interparticle forces the effect of gravitation is incorporated in both terms rather than using an implicit function for the effect of the aerodynamic forces as reported earlier in literature a constant aerodynamic coefficient was introduced from consideration of the van der waals force between two particles it was further shown that the effect of the interparticle cohesion force between two dry particles on the deflation threshold should be inversely proportional to the particle diameter squared the interparticle force was further extended to include wet bonding forces the latter were considered as the sum of capillary forces and adhesive forces a model that expresses the capillary force as a function of particle diameter squared and the inverse of capillary potential was deduced from consideration of the well known model of fisher and the young laplace equation the adhesive force was assumed to be equal to tensile strength and a function which is proportional to particle diameter squared and the inverse of the potential due to adhesive forces was derived by combining the capillary force model and the adhesive force model the interparticle force due to wet bonding was simplified and written as a function of particle diameter squared and the inverse of matric potential the latter was loglinearly related to the gravimetric moisture content a relationship that is valid in the low moisture content range that is important in the light of deflation of sediment by wind by introducing a correction to force the relationship to converge to zero moisture content at oven dryness the matric potential moisture content relationship contained only one unknown model parameter viz moisture content at 1 5 mpa working out the model led to a rather simple parameterisation containing only three coefficients two parameters were incorporated in the term that applies to dry sediment and were determined by using experimental data as reported by iversen and white sedimentology 29 1982 111 the third parameter for the wet sediment part of the model was determined from wind tunnel experiments on prewetted sand and sandy loam aggregates the model was validated using data from wind tunnel experiments on the same but dry sediment and on data obtained from simulations with the model of chepil soil sci soc am proc 20 1956 288 the experiments showed that soil aggregates should be treated as individual particles with a density equal to their bulk density furthermore it was shown that the surface had to dry to a moisture content of about 75 of the moisture content at 1 5 mpa before deflation became sustained the threshold shear velocities simulated with our model were found to be in good agreement with own observations and with simulations using chepil s model

estimation of the long term slip surface uplift and block rotation along the northern strand of the north anatolian fault zone inferences from geomorphology of the almacik block abstract the almacik block is one of the key morphotectonic units in the eastern marmara region associated with the long term slip partitioning within the north anatolian fault zone nafz in this study we provide new geomorphic reconstructions of offset drainage basins morphometric analysis of topography and longitudinal profiles of the rivers crossing different flanks of the almacik block our geomorphic reconstructions of offset drainage basins along the hendek and karadere faults imply mean offsets of 2 3 0 4 km and 8 4 0 7 km respectively during the quaternary our dataset also imply that slip partitioning occurs in a broader zone than previously proposed and that the total 10 7 0 6 km offset along the hendek and karadere faults of the northern strand must be taken into account for long term slip partitioning in the eastern marmara region together with previously suggested 10 km offset along the southern strand yaltirak 2002 16 1 0 km offset along the middle strand ozalp et al 2013 and the 52 1 0 km offset along the mudurnu segment of the northern strand akbayram et al 2016 our newly proposed geomorphic markers raise the cumulative offset in the eastern marmara region associated with the naf to 89 1 0 km since the latest pliocene quaternary in addition to these lateral displacements our morphometric analysis and longitudinal profiles of the rivers imply up to 1130 130 m surface uplift of the almacik block as a combined result of vertical displacement within the deformation zone of the northern strand of the nafz finally by assuming that river basins act as passive deformation markers our basin azimuth analyses imply 20 2 clockwise rotation of the almacik block associated with the nafz

fluid present anatexis of metapelites at el joyazo se spain constraints from raman spectroscopy of graphite the garnet biotite sillimanite anatectic xenoliths in the neogene dacite dome of el joyazo also called cerro de hoyazo se spain contain four types of graphite i to iv distinguished on the basis of grain size and texture structural characterization of graphite by laser raman spectroscopy lrs shows systematic differences in the degree of ordering among the four types only type iii is fully consistent with the granulite facies conditions reached by the xenoliths during partial melting the others indicate metamorphic temperatures covering amphibolite facies conditions with only a few examples of granulite grade crystallinity all graphite crystallized before or during the anatectic event indicating that a large fraction of the graphite did not equilibrate at peak temperatures the mm scale coexistence of different types and degrees of ordering in the graphite suggests different origins i e of biogenic derivation and fluid deposited and is explained in terms of fluid melt graphite interaction during the anatectic event disequilibrium behaviour during high temperature metamorphism and anatexis is typical of types i ii and particularly of iv and is attributed to sluggish kinetics of solid state graphitization mainly owing to the limited time of the process and carbon saturation of the intergranular fluid the coexisting well ordered type iii graphite is the product of melting in the presence of a graphite saturated fluid a process that would account for the deposition of new graphite the lrs results together with petrologic observations suggest that it is possible that high melt fractions can be generated by fluid present melting of a metasedimentary protolith also in a closed system although this contradicts the commonly accepted hypothesis that due to limited rock porosities extensive fluid present melting is precluded unless infiltration occurs it is a possible end member model in anatectic settings characterized by rapid heating rates and low grade source rocks

the nature distribution and formation of pans in arid zones abstract pans closed depressions are a widespread feature of many of the world s drylands by using literature survey air photographs topographic maps orbital photographs and imagery combined with field work it is possible to describe the major areas where these features occur their distribution is controlled to a great extent by the availability of susceptible surfaces they also develop in certain particular environmental settings palaeolacustrine basins palaeodrainages interdunes and on coastal plains many of the pans have a distinctive morphology while on their lee sides they may have lunette dunes many processes combine to create and maintain pans and these can be considered in a general model which has certain key elements the first of these is that the area should not be one where fluvial processes are fully integrated it should also not be one where aeolian accumulation is such as to infill any irregularities in the land s surface if these two predisposing conditions are fulfilled then under dryland conditions if susceptible surfaces are present there are various circumstances that may lead to hollow development and enlargement although in some cases such processes as solution suffosion and animal activities may play a role we believe that the predominant reason why pans have the characteristics that they do including their shapes lunettes alignments etc is that they result from the operation of the twin processes of salt weathering and aeolian deflation

neoproterozoic palaeogeography of the cadomia and avalon terranes constraints from detrital zircon u pb ages detrital zircons from three neoproterozoic sandstone units from the cadomia terrane of northern france and the channel islands yield ages in three broad groups late neoproterozoic 650 600 ma early palaeoproterozoic 2 4 2 0 ga and archaean 2 5 ga the lack of mesoproterozoic zircon crystals combined with the high abundance of grains between 2 20 and 2 00 ga corresponds closely to the ages of exposed rocks in the west africa craton and thus it is suggested that cadomia was in close proximity to west africa by c 580 ma in contrast the main age groups of detrital zircon from the neoproterozoic avalon terrane are mesoproterozoic and there is a distinct gap of ages between 2 40 and 2 05 ga these significant differences suggest that the two terranes were in different locations relative to major gondwanan cratons in latest neoproterozoic time

processes of silicate karstification associated with pan formation in the darwin koolpinya area of northern australia lyons lagoon one of many small pans near darwin northern australia occurs in lateritized terrain formation by structurally facilitated silicate karsti cation of the parent cretaceous sandy sediments was earlier proposed this paper presents the results of thin section microscopy and scanning electron microscopy with energy dispersive x ray study of pan sediments with a view to assessing the extent to which they re ect the geomorphological hydrogeological history severe corrosion was found to overprint the impact features of the primary sands attributed to aggressive leaching and consistent with formation of the depression by karsti cation when the water table was low formation of a smectitic matrix is considered to have followed when the water table was high upon subsequent lowering of the water level leaching was resumed altering smectite to kaolinite and resulting in incongruent dissolution of kaolinite to leave a siliceous residuum at least two cycles of high followed by low water levels are recognized such periodic changes of levels are considered essential to pan formation within freely draining lateritic terrain the processes of pan formation and alteration of pan sediments essentially residual deposits is ongoing biocorrosion being implicated as an important mechanism incongruent kaolinite dissolution to leave a silica residuum a hitherto apparently unrecognized process raises the possibility that silcrete may form as a relative accumulation which is synchronous with lateritic leaching in more elevated topographic positions copyright 2004 john wiley sons ltd

simultaneous observations of the critical aeolian threshold of two surfaces abstract threshold is an important parameter in wind erosion research and in the field of aeolian research in general a new technique was recently developed that provides a means of determining threshold with a sampling system that continuously collects wind data along with critical information regarding saltation activity by employing two identical sampling systems it was possible to monitor the threshold of a highly mobile sand surface while simultaneously monitoring the threshold of a less mobile playa surface results indicate that threshold could be measured at both locations with enough precision to establish clear differences between the surfaces the sandy surface at the morgenstern dunes site was considerably more active than the yellow lake playa site over the 113 day sampling period because of its consistently lower threshold the morgenstern site tended to maintain a fairly constant threshold of around 5 4 to 5 5 m s whereas the threshold of the yellow lake playa surface varied from a low of 6 4 m s to values greater than 13 3 m s limitations of this method lie in the fact that threshold can be determined only when winds are blowing sufficiently strongly to cause sediment transport

monitoring the 1980 1982 eruptions of mount st helens compositions and abundances of glass the mount st helens eruptive sequence of 1980 through 1982 reflects the tapping of successively less water rich more highly crystallized and more viscous highly phyric dacitic magmas these changes reflect both syn and preeruption processes the decreasing water content points to a continued decline in the volume and intensity of explosive pyroclastic activity this decreasing water content appears to be composed of a long term trend established during a long period of repose about 130 years imposed on short term trends established during short periods about 7 to 100 days of repose between eruptions in the present eruptive cycle the last two eruptive cycles of this volcano the t a d 1800 and w cycles about a d 1500 exhibited similar trends these changes are inferred from a combination of petrographic bulk chemical and electron and ion microprobe analyses of matrix and melt inclusion glasses

petrogenesis of oceanic plagiogranites by partial melting of gabbros an experimental study we performed hydrous partial melting experiments at shallow pressures 0 2 gpa under slightly oxidizing conditions nno oxygen buffer on oceanic cumulate gabbros drilled by odp ocean drilling program cruises to evaluate whether the partial melting of oceanic gabbro can generate sio2 rich melts with compositions typical of oceanic plagiogranites the experimental melts of the low temperature runs broadly overlap those of natural plagiogranites at 940 c the normalized sio2 contents of the experimental melts of all systems range between 60 and 61 wt and at 900 c between 63 and 68 wt these liquids are characterized by low tio2 and feotot contents similar to those of natural plagiogranites from the plutonic section of the oceanic crust but in contrast to fe and ti rich low temperature experimental melts obtained in morb systems at 950 c the 1 500 m long drilled gabbroic section of odp hole 735b legs 118 and 176 at the southwest indian ridge contains numerous small plagiogranitic veins often associated with zones which are characterized by high temperature shearing the compositions of the experimental melts obtained at low temperatures match those of the natural plagiogranitic veins while the compositions of the crystals of low temperature runs correspond to those of minerals from high temperature microscopic veins occurring in the gabbroic section of the hole 735b this suggests that the observed plagiogranitic veins are products of a partial melting process triggered by a water rich fluid phase if the temperature estimations for high temperature shear zones are correct up to 1 000 c and a water rich fluid phase is present the formation of plagiogranites by partial melting of gabbros is probably a widespread phenomenon in the genesis of the ocean crust

earth hummocks thufur new insights to their thermal characteristics and development in eastern lesotho southern africa the aspect controlled variations in soil freezing within earth hummocks of eastern lesotho southern africa are analysed ground thermal data were measured for an earth hummock from late autumn to early spring in 1995 and 1996 using tinytalk data loggers during 1995 ground temperatures were recorded at 15 and 20 cm depth on the hummock north east south and west aspects whilst in 1996 temperatures were recorded at 1 cm 5 cm and 10 cm on the north and south aspects the data from 1995 indicate that soil freezing commences on the hummock southern aspects and gradually progresses towards the western and northern aspects whilst the eastern aspect remained unfrozen throughout winter the data from 1996 indicate that a thick snow cover almost nullifies the temperature differences between the hummock northern and southern aspects however given the relative absence of snow during contemporary winters freeze intensity and duration is longest on the hummock southern and western aspects which helps explain earth hummock deformation elongation and coalescence in a southwesterly direction on slope gradients 3 copyright 2005 john wiley sons ltd

variscan amphibolite facies rocks from the kurtoglu metamorphic complex gumushane area eastern pontides turkey the kurtoglu metamorphic complex that forms part of the pre liassic basement of the sakarya zone in northern turkey consists of at least two tectonic units blueschist facies rocks of unknown metamorphic age in the southern part of the complex are tectonically overlain by variscan low pressure high temperature metamorphic rocks the latter comprise mica schists and fine grained gneisses cut by metaleucogranitic dikes as well as migmatitic biotite gneisses and subordinate amphibolite intercalations structural data indicate that metamorphism and penetrative deformation occurred after dyke intrusion peak metamorphic conditions of the mica schists fine grained gneisses and metaleucogranites are estimated to 650 c and 0 4 gpa based on phase relationships in the system nckfmash fe mg partitioning between garnet and biotite as well as garnet aluminosilicate quartz plagioclase gasp and garnet plagioclase biotite quartz gbpq barometry peak temperatures of the migmatitic biotite gneisses and amphibolite intercalations are not well constrained but might have been significantly higher 690 740 c as suggested from hornblende plagioclase thermometry 40ar 39ar incremental dating on muscovite and biotite fractions from the mica schists and fine grained gneisses yielded plateau ages of 323 ma significantly older model ages of 329 and 337 ma were obtained on muscovite fractions from two metaleucogranite samples these fractions contain both relict igneous and newly formed metamorphic muscovite

an integrated study of the ne german basin abstract the ne german basin is part of the southern permian basin south of the transeuropean suture zone tesz here we report an attempt to integrate a variety of geological and geophysical data in order to reveal the present day deep crustal structure of the ne german basin special focus is taken on detailed geological information available reflection seismic data wide angle refraction seismic data and gravity data based on this integrative approach a concise crustal model is developed which can be subject to further evaluation furthermore it is shown that the ne german basin is an outstanding feature quite different from classical basin types as the moho is flat below the basin neither a simple shear nor a pure shear extension model can be applied instead a thick high velocity lower crustal layer is present below the basin centre this high velocity lower crust is also observed in the western part of the basin and can be taken as characteristic for east avalonia results of gravity modelling indicate the presence of a high density lower crust thus supporting the wide angle data furthermore changes in crustal structure can be derived from changes in reflectivity pattern and from the gravimetric signature along the elbe fault system indicating the presence of different crustal domains north and south of the fault system an elastic plate model where the forces applied are the sediment load a vertical load at the southern margin accounting for the harz moutains and a nne ssw directed compression indicates a buckling of the crust during late cretaceous to tertiary inversion however the correlation between the observed crustal structure and the tectonic events that have affected the area remains a subject of discussion a permian thermal event affected the upper mantle and the lower crust and therefore may have modified the crustal memory with regard to caledonian and variscan events additional tectonic events affected the area during the mesozoic in conclusion it remains an open question whether the high velocity and high density lower crustal structure represents a remnant of east avalonia whether it is related to the formation of the permo triassic basin or is the cumulative result of a series of events during the palaeozoic and mesozoic

u pb and sm nd geochronology of the kizildag hatay turkey ophiolite implications for the timing and duration of suprasubduction zone type oceanic crust formation in the southern neotethys the kizildag hatay ophiolite in turkey represents remnants of the southern neotethyan ocean and is characterized by a complete ocean lithospheric section it formed in a fore arc setting above a n dipping intraoceanic subduction zone and represents the undeformed more northerly part of the same thrust sheet that also forms the baer bassit ophiolite to the south the ophiolite was emplaced southwards from the southerly neotethyan ocean in maastrichtian time u pb and sm nd dates are used to constrain the crystallization age and duration of magmatic activity of the kizildag ophiolite u pb dating yielded ages of 91 7 1 9 ma for a plagiogranite and 91 6 3 8 ma for a cumulate gabbro the cumulate gabbro also yielded a sm nd isochron age of 95 3 6 9 ma the measured ages suggest that the oceanic crust of the kizildag ophiolite formed in a maximum time period of 6 ma and that the plagiogranite may have formed later than the gabbroic section the u pb zircon ages from the kizildag ophiolite and the cooling age of a metamorphic sole beneath the baer bassit ophiolite are indistinguishable within the analytical uncertainties this indicates the presence of young and hot oceanic lithosphere at the time of intraoceanic subduction thrusting in the southern neotethys the u pb zircon ages from the kizildag the troodos and the semail ophiolites overlap within analytical uncertainties suggesting that these ophiolites are contemporaneous and genetically and tectonically related within the same late cretaceous southern neotethyan ocean

melt production during granulite facies anatexis experimental data from primitive metasedimentary protoliths we conducted fluid absent partial melting experiments at 0 5 and 1 0 gpa in the temperature range 750 to 1000 c to investigate the influence of bulk rock mg 100mg mg fe and the effects of additional tio2 on the granulite grade anatectic evolution of relatively magnesian metapelites and metagreywackes in these experiments melting began between 780 and 830 c by the incongruent breakdown of biotite to produce quartz saturated granulite facies residual mineral assemblages in equilibrium with h2o undersaturated granitic melt the glass quenched melt compositions produced in this study vary little generally the glasses have compositions similar to those of many natural strongly peraluminous leucogranites the solidus temperatures in both rock types increase with increasing mg but are unaffected by the presence or absence of a tio2 component at 0 5 gpa the metapelites melted at temperatures up to 50 c lower than the equivalent metagreywackes but at 1 gpa there was no discernible difference this study suggests that the fluid absent solidus has a steep positive dp dt slope in metapelites and steep negative dp dt slope in metagreywackes the pattern of melt production with increasing temperature is strongly controlled by the upper limit of biotite stability in tio2 free compositions this was found to increase by 15 to 20 c in the metapelites and by 30 to 40 c in the metagreywackes as a function of increasing mg from 49 to 81 the presence of a tio2 component increases the upper limit of biotite stability by 50 c in the metapelites and by 80 c in the metagreywackes over that observed in the equivalent tio2 free compositions in consequence in the tio2 free samples large pulses of melt up to 35 wt are produced over narrow temperature ranges as little as 15 c in these experiments between 830 and 875 c in the tio2 bearing samples the major pulse of melt production occurs more gradually between 830 and 900 c

lower palaeozoic stratigraphy and palaeontology karadere zirze area pontus mountains northern turkey lower palaeozoic rocks in the karadere zirze area east of safranbolu pontides northern turkey range from early ordovician to silurian overlying the probably tremadoc bakacak formation are aydos formation quartzites followed conformably by the karadere formation dated as early arenig to early llanvirn by means of graptolites which are assigned to seventeen genera and include three new forms eoglyptograptus bouceki prolasiograptus haplus praecursor and undulograptus mui late arenig trilobites from the karadere formation include bergamia cyclopyge dionidella leioshumardia and seleneceme in the limestone member of the overlying ketencikdere formation uncommon trilobites suggest only a mid to late ordovician age but con odonts with colour alteration index 5 6 indicate the amorphognathus tvaerensis biozone early caradoc macrofossils are rare in the siltstone member but conodonts from the middle of the unit suggest the highest subzone of the a tvaerensis biozone the youngest visible strata are on acritarch evidence at least as high as caradoc but the ashgill is not confirmed and the contact with overlying silurian rocks is unexposed the findikli formation comprises a lower member black argillites with llandovery graptolites and acritarchs and an upper member grey shales with late wenlock graptolites overlain unconformably by devonian rocks the succession differs significantly from contemporaneous deposits in southern turkey and its affinities lie with western europe including the welsh basin

uranium lead isotopic ages of plagiogranites from the troodos ophiolite cyprus and their tectonic significance zircon populations from two plagiogranites in the plutonic section of the troodos ophiolite yield u pb dates between 90 3 0 7 and 92 4 0 7 ma zircons from one of the two samples yield u pb dates of 90 3 0 7 and 92 1 0 7 ma this difference is greater than our analytical error and the zircons are therefore considered to be slightly discordant two fractions from another sample are internally and externally concordant and have an average date of 91 6 1 4 ma this date is adopted as the age of plagiogranite crystallization the plutonic section of the troodos ophiolite is complex in that several generations of intrusion can be identified the plagiogranites occur at the top of the intrusive section and represent fractionated residua of magma chambers related to the lower pillow lavas they are possibly slightly older than small ultramafic layered complexes that represent the final intrusive episode within the troodos ophiolite there is good agreement between our results and the ages of radiolaria which occur in umbers intercalated with the upper pillow lavas of troodos blome and irwin 1985 this shows that the 75 to 85 ma k ar dates on the lavas and sheeted dikes desmet et al 1978 delaloye and desmet 1979 delaloye et al 1980 staudigel et al 1986 represent age resetting unrelated to ophiolite formation the troodos u pb zircon ages are slightly lower than u pb zircon ages from the samail ophiolite in oman which vary between 93 5 and 97 9 ma and average 95 ma tilton et al 1981 the small difference in age between the troodos and the samail ophiolites and the geochemical similarities of basalts from both complexes to island arc volcanic rocks imply that a 3000 km axis of rift related island arcs formed between 91 and 98 ma emplacement of the ophiolites followed during the early maastrichtian

early mesozoic subduction in the eastern mediterranean evidence from triassic eclogite in northwest turkey an eclogite forms a 40 m long tectonic lens enveloped in serpentinite within a metabasite phyllite marble unit of permian triassic age in northwest turkey the eclogite consists mainly of garnet omphacite glaucophane and epidote it is associated with other lenses of serpentinite and metagabbro single grain laser probe 40ar 39ar dating of phengites from the eclogite gives ages of 203 to 208 ma corresponding to the triassic jurassic boundary regional geologic considerations also suggest a latest triassic to earliest jurassic metamorphic age for the eclogite and the enclosing metabasite marble phyllite unit the eclogite along with serpentinite and gabbro lenses were probably emplaced as diapirs into the metabasite phyllite marble unit during late triassic subduction the eclogite provides evidence for the often elusive triassic subduction history of the paleo tethys in the eastern mediterranean area

nanogranite and glassy inclusions the anatectic melt in migmatites and granulites using as a case study a granulite from the kerala khondalite belt india we show that a former anatectic melt can be preserved as tiny 25 m droplets within refractory minerals in this case garnet the melt is either fully crystallized as a qtz ab kfs bt cryptocrystalline aggregate nanogranite or completely glassy in inclusions 15 m both nanogranite and glassy inclusions have a peraluminous ultrapotassic granitic composition that in this case does not correspond to a minimum melt and points to high melting temperatures in agreement with the ultrahigh temperature origin of the rock this discovery indicates that peritectic minerals growing during incongruent melting reactions act as hosts for inclusions of anatectic melt and that in the general case of slow cooling of the crust these inclusions will occur as nanogranite exceptionally in the smallest inclusions glass may be present due to inhibition of crystallization our results extend the frontiers of petrological and geochemical research in crustal melting as the composition of natural anatectic melts can be directly analyzed rather than assumed

geochronology of the karadere basement nw turkey and implications for the geological evolution of the istanbul zone earlier geological work in the istanbul zone western pontide tectonic belt has revealed the presence of extensive basement outcrops exposed underneath palaeozoic and mesozoic to tertiary cover sequences the basement of suspected neoproterozoic age plays an important role in understanding the crustal accretion process in nw turkey we report the first results of a detailed pb pb and u pb zircon study complemented by nd sr whole rock and mineral data from basement rocks exposed in the karadere valley safranbolu area five samples were selected for this study comprising three metagranitoids and two metasediments zircon geochronology indicates that the metagranitoids were formed during late proterozoic pan african magmatic events between 590 and 560 ma the rocks are of tonalitic and granitic composition and have low nb y ratios and ti contents consistent with those of arc rocks a continental arc setting is supported by their sr and nd isotope data that indicate a contribution of a mantle source as well as crustal assimilation during magma genesis the metasediments can clearly be distinguished from the metagranitoids by their higher 87sr 86sr ratios and lower end values at 580 ma which supports the suggestion that the arc was underlain by mature continental crust zircons from the metasediments yield a range of pb pb ages between 1 860 and 710 ma thirty per cent of them fall between 890 and 710 ma possibly suggesting a derivation from gondwana afro arabian regions a sm nd garnet whole rock analysis obtained on a metagranite gives an age of 559 8 ma which either reflects pre metamorphic magmatic growth of garnet in a felsic melt or a syntectonic high temperature metamorphic event uplift and cooling of the basement is further constrained by rb sr biotite ages of 548 545 ma these lower cambrian mineral ages demonstrate that the istanbul zone was not thermally reactivated during the hercynian cimmerian or alpine orogeny in contrast to its neighbouring tectonic zones confirming its role as a suspect terrane in the modern western pontide tectonic belt

immiscibility between carbonic fluids and granitic melts during crustal anatexis a fluid and melt inclusion study in the enclaves of the neogene volcanic province of se spain in the restitic crustal enclaves in the neogene volcanics of el hoyazo and mazarron se spain associations of fluid and silicate melt inclusions indicative of immiscibility are frequently observed in the bt poor crd rich graphitic metapelites these occurrences extremely rare for anatectic crustal rocks have been studied by microthermometry micro raman spectroscopy and emp analysis both at el hoyazo and mazarron the immiscible fi and mi are hosted in plagioclase and cordierite with microstructures that suggest primary trapping the fi hosted in cordierite are monophase whereas they may contain crystals of calcite when hosted in plagioclase indicating fluid host reaction during cooling decrepitation microstructures have not been observed the mi contain fresh glass of peraluminous felsic rhyolitic composition typical of anatectic s type melts in all samples the fluids are co2 dominated n85 mol with minor amounts of n2 and ch4 and traces of co and h2 the nucleation of graphite induced by the laser beam in some inclusions demonstrates that the fluids are graphite saturated large scatter in microthermometric behaviour of fi indicates significant density variations only in one sample from el hoyazo are fluid densities compatible with the estimated p tconditions of trapping 5 7 kbar 850 50 c whereas in the remaining samples the extremely low densities suggesting trapping pressures b1 kbar are in contrast with the microstructural indications of primary entrapment and little evidence of decrepitation in addition although some measured compositions are compatible with c o h n fluid speciation at the estimated p t conditions of anatexis the lack of h2o in all fi is inconsistent with the slightly hydrated character of coexisting glasses the possible mechanisms accounting for departure of densities and compositions of fi from expected values are discussed and leakage of h2o suggested as the most plausible

morphodynamics and climate controls of two aeolian blowouts on the northern great plains canada blowouts are the most regionally pervasive active aeolian landform on the northern great plains of north america this study reports a long term investigation into the morphological development of two adjacent blowouts in a continental dune field the blowouts were monitored for a decade in the bigstick sand hills of southwestern saskatchewan canada topographic changes were determined from dense arrays of erosion pins in each blowout 1 per 4 m2 n 171 and 1 per 16 m2 n 150 pin measurements were made 16 times between may 1994 and may 2004 over the decade both blowouts expanded and more than doubled in volume differences in form flow interactions have caused the larger of the two blowouts to deposit more than a metre of sediment within the deflation basin and the smaller blowout to erode by more than a metre a negative feedback effect was triggered when the larger blowout reached a critical size around 1994 60 m 36 m 8 1 m length width height when sediment was no longer eroded from the deflation basin a positive feedback in the smaller blowout continues to facilitate erosion from the deflation basin monthly observations since 2002 indicate that aspect plays an important role in the development of these blowouts by creating a spatial asymmetry in sediment availability sediment is more readily available throughout the year on south facing slopes which receive greater insolation than north facing slopes and are often drier and more frequently thawed in this cold climate environment comparisons between climate data from a remote meteorological station 45 km to the southwest and sediment transport indices developed from the erosion pin data produced very few correlations significant at the 95 per cent confidence level nevertheless the signs of the correlation coefficients indicate that sediment erosion and deposition in both blowouts respond similarly to the following climate variables recorded at the remote station i the amount of precipitation ii the transport capacity of the wind and iii transporting winds from a directional wedge between 180 and 330 taken altogether the results from this study highlight the importance of climate and feedback effects in blowout development that may be extended to other blowouts in continental and coastal settings copyright 2006 john wiley sons ltd

reconstructing the deformation of the north anatolian fault zone through restoring the oligo miocene exhumation pattern of the almacik block northwestern turkey based on the apatite u th he ages the almacik block is an approximately 73 km long and 21 km wide tectonic sliver formed by the north anatolian fault zone in northwestern turkey morphologically it is one of the most pronounced st

tectonic evolution of the intra pontide suture zone in the armutlu peninsula nw turkey abstract the armutlu peninsula and adjacent areas in nw turkey play a critical role in tectonic reconstructions of the southern margin of eurasia in nw turkey this region includes an inferred intra pontide oceanic basin that rifted from eurasia in early mesozoic time and closed by late cretaceous time the armutlu peninsula is divisible into two metamorphic units the first the armutlu metamorphics comprises a precambrian high grade metamorphic basement unconformably overlain by a palaeozoic low grade mixed siliciclastic carbonate volcanogenic succession including bimodal volcanics of inferred extensional origin with a possibly inherited subduction signature the second unit the low grade iznik metamorphics is interpreted as a triassic rift infilled with terrigenous calcareous and volcanogenic lithologies including basalts of within plate type the triassic rift was unconformably overlain by a subsiding jurassic late cretaceous cenomanian passive margin including siliciclastic carbonate turbidites radiolarian cherts and manganese deposits the margin later collapsed to form a flexural foredeep associated with the emplacement of ophiolitic rocks in turonian time geochemical evidence from meta basalt blocks within ophiolite derived melange suggests a supra subduction zone origin for the ophiolite the above major tectonic units of the armutlu peninsula were sealed by a maastrichtian unconformity comparative evidence comes from the separate almacik flake further east considering alternatives it is concluded that a mesozoic intra pontide oceanic basin separated eurasia from a sakarya microcontinent with a wider northern neotethys to the south lateral displacement of exotic terranes along the south eurasian continental margin probably also played a role e g during late cretaceous suturing in addition to overthrusting

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

particle size and sorting characteristics of sand in transport on the stoss slope of a small reversing dune studies of the particle size and sorting characteristics of sand on the stoss slope of a 6 m high reversing dune show that the sand in transport is generally finer and better sorted than surface sand at the same position on the slope the sand in transport becomes coarser and more poorly sorted as wind speed and rates of mass transport increase toward the dune crest these patterns reflect changes in the competence of the wind which is capable of transporting larger grains and a wider range of grain sizes as its speed increases in space and time our field observations suggest that the particle size and sorting characteristics of surface sand are highly dependent on antecedent wind conditions and are not an invariant property of the dune as is widely assumed the wide range of particle sizes on the surface as well as its change through time also has important implications for modeling sediment transport on dunes transport thresholds may vary by as much as 30 on the stoss slope of the study dune

relations between morphology air flow sand flux and particle size on transverse dunes taklimakan sand sea china field experiments on two isolated transverse dunes with different scales in the taklimakan sand sea show that particle size and slope control the threshold shear velocity and sand flows on the stoss of the dunes the decreased threshold shear velocity and the unsaturated sand flows are the main reasons why sands are not deposited at the toe of the dunes the particle size controls sand flux through its influence on the aerodynamic roughness elements and threshold shear velocities the sand flux is different for dune surfaces with different particle size distributions under the control of the medium to low stress of the drifting sand winds the results of the field experiments and particle size analysis showed that sand transport had little influence on the particle size distributions the mean particle size being transported on the stoss is lower than that on the dune surface it is difficult to determine whether or not the wind is fully saturated with sands when sand flux calculation is mainly dependent on the shear velocity and the mean particle size the sands within some range of the particle size are transported and developed into simple transverse dunes and then the interdune surface is coarsened and alternated with the draas in the taklimakan sand sea copyright 2002 john wiley sons ltd

dynamic processes of a simple linear dune a study in the taklimakan sand sea china samples of dune sands surveys of the morphology and field measurements of wind velocity and direction of a simple linear dune in taklimakan sand sea show that the airflow and sand flux vary with the change of wind direction on the dune surface decrease of the airflow stress on the lee flank does not result in much decrease of the sand flux because of the low threshold shear velocities and the airflow conditions there are no significant relations between the sand flux on the lee flank and the angle of incidence of the airflow the low threshold shear velocities and the maintenance of the sand flux at the lee flank are the main mechanisms keeping the linear shape of the dunes measurements of the sand flux shows that it reaches a maximum on the crest of the dune the grain size of the transported sands has some differences compared to that of the dune surface the sands transported are finer than that on the dune surface but better sorted under the influence of the medium to low wind activity the field experiment results exhibit that it is possible for the dunes to be shaped as linear dunes during the processes of accumulation and elongation

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

testing models of late palaeozoic early mesozoic orogeny in western turkey support for an evolving open tethys model field evidence from north south transects tests three tectonic models for tethys in western turkey for when a late palaeozoic ocean was closing and an early mesozoic ocean opening in model 1 a palaeozoic ocean subducted southwards rifting continental fragments from gondwana and opening a triassic neo tethys to the south closure and collision occurred by latest triassic time in model 2 a wide palaeozoic tethys subducted northwards with an active eurasian margin and a passive gondwana margin the northern gondwana margin rifted in the triassic fragments either remained nearby taurides or drifted northwards e g karakaya attached to a north subducting plate new oceanic crust replaced palaeo tethys with neotethys and back arc marginal basins opened along the south eurasian margin e g kure in model 3 a palaeozoic ocean also subducted northwards opening wide marginal basins a wide southern neotethys opened along the gondwana margin rifted eurasian anatolides and gondwana taurides fragments collided in mid tethys by latest triassic time field evidence from the pontides supports north dipping subduction models model 2 or 3 above key features are a south vergent hp lt accretionary prism magmatic arc and back arc basin system bordering the eurasian margin also evidence from the tauride mountains favours model 2 over model 3 critically the anatolides and taurides appear to have a common history and were unlikely to have been located on opposite sides of tethys as in model 3

influence of cryptogamic crust disturbance to wind erosion on sand and loam rangeland soils a portable field wind tunnel was used to assess the sediment flux rates of loam and sand textured soils in the mallee region of southeastern australia three levels of crust disturbance nil moderate and severe simulating stock trampling were investigated the results demonstrated the importance of cryptogamic crusts in binding the soil surface and providing roughness after the soil was moderately disturbed on the loamy soil the crust helped maintain sediment flux rates below the erosion control target to 5 g m 1 s 1 for a 65 km h 1 wind measured at 10 m height once the crust was severely disturbed sediment fluxes increased to 1 6 times the erosion target on the sandy soil even with no crust disturbance the sediment flux was 1 6 times the erosion control target disturbing the crust increased sediment fluxes to a maximum of 6 7 times the erosion control target removal of the crust also decreased the threshold wind velocity that resulted in an increase to the ris k of erosion from 5 per cent to 20 per cent 1998 john wiley sons ltd