mid ocean ridge and island arc affinities in ophiolites from iran palaeographic implications complementary reference abstract fifty six samples of ophiolitic rocks from various late cretaceous eocene suture zones in iran have been analyzed for major and trace elements in order to assess their petrogenetic affinity and to determine their original tectonic setting in both southern baluchestan i e between the makran range and the lut block the fanuj maskutan sequence and northeastern baluchestan i e in the east iranian ranges the tchehel kureh sequence the ophiolitic complexes are well developed the rocks display affinities with mid ocean ridge tholeiites the basaltic rocks are comparable to respectively transitional fanuj maskutan and normal tchehel kureh morb in contrast the sequence along the zagros the sahneh sequence appears to have formed in an island arc setting in iranshar i e in southeastern baluchestan ophiolites are dismembered into a melange which includes cumulate intrusives similar to those from fanuj maskutan and lavas with island arc tholeiitic affinity a similar island arc origin may be inferred for the sabzevar ophiolitic sequence north of the lut block studied by other authors the chemical data thus help to elucidate the development of the jigsaw puzzle of microplates of gondwanian origin that during the mesozoic were intermediate in position between afro arabia india and eurasia and that now constitute the middle east ophiolite obduction in iran occurred during arc basin continent or ocean continent collisions in the late cretaceous early paleogene largely predating the final suturing between arabia and india with eurasia to which the intermediate microplates were already attached which did not take place before the neogene

aptian albian palaeogeography of neo tethyan domain abstract the aptian albian interval 124 5 97 0 ma was a critical time both globally and for the tethyan domain in the tethyan domain it was the time when a united neo tethyan subduction zone became established between the future site of the alps and southeast asia and greatly accelerated the rate of north south convergence throughout the tethyan region a consequent widespread transgression on both laurasian and gondwanian margins deposited orbitolina limestones and associated clastics on wide continental shelf areas on the sea floor of the neo tethys ocean organic rich siliceous black shales radiolarites and turbidites with minor amounts of carbonates were deposited siliceous black shales accumulated under euxinic conditions of restricted small ocean basins of the neo tethyan realm and along their margins these areas received large amounts of organic debris from deltaic areas and coastal plains of the neighbouring continental shelves following the establishment of the north dipping subduction zone the laurasian passive margin was largely converted to an active one fringed by a large number of magmatic arcs that greatly influenced the sedimentation on the margin land areas and continental basins were widespread on this margin in northern tibet china and indo china this was a consequence of the late triassic to early jurassic continental collissions and accompanied intracontinental convergence that lasted well into the cretaceous a detailed aptian albian facies map and a crude palinspastic palaeogeographic map of the entire tethyan realm are prepared in order to express the contrasts in sedimentation on laurasian and gondwanian margins and to show the compatibility of the presented data with the most recent and reliable reconstructions of the major tectonic elements in tethysides

40ar39ar ages and tectonic setting of ophiolite from the neyriz area southeast zagros range iran abstract an ophiolite considered to be an allochthonous fragment of tethyan oceanic crust and mantle crops out near neyriz in the zagros range iran 40 ar 39 ar ages ranging from 76 8 23 8 ma to 105 23 3 ma were measured on hornblende from five samples of plagiogranite and diabase from the ophiolite the most precise ages are 85 9 3 8 ma for a diabase and 83 6 8 4 ma for a plagiogranite the weighted mean age of hornblende from the five samples is 87 5 7 2 ma which indicates that the igneous part of the neyriz ophiolite formed during the early part of the late cretaceous pargasite from amphibolite below peridotite of the neyriz ophiolite has a 40 ar 39 ar age of 94 9 7 6 ma the pargasite age agrees within analytical uncertainty with the ages measured on diabase and plagiogranite comparable ages have been measured on igneous rocks from the samail ophiolite of oman and on amphibolite below peridotite of the samail ophiolite

tethys and transit plate patterns viewed against long term periodicity of magnetic field reversals abstract using a recent step by step reconstruction of the mesozoic tethys ocean and surrounding continents we draw the topologic patterns which characterise the networks of plate boundaries for pre tethys tethys and post tethys times we define an asymmetric transit pattern which affected the eastern and central tethys it operated permanently from the pre tethys to today s post tethys times and thus cannot be responsible for having created and later destroyed the mesozoic tethys the whole tethys pattern is obtained through adding the symmetric pattern in fact the early atlantic pattern which affected the western and central tethys this tethys pattern actually governed the birth and growth of the oceanic realm and operated only during tethys times being preceded and followed by anti tethys patterns which governed the late paleozoic and cenozoic collisions the two switchovers from a pattern to its opposite correspond timewise with the kiaman long reverse and the cretaceous long normal superchrons which define the long term pseudo periodicity of the magnetic field reversals thus suggesting a coupling process between the core of the earth and the topology of plate boundaries in the lithosphere

direct push sensing in wetland geo archaeology high resolution reconstruction of buried canal structures fossa carolina germany abstract geo archaeological trenching techniques in floodplain and wetland environments are challenging due to the impact of groundwater inflow and highly unstable trench edges alternatively classical driving core techniques often correspond with the contraction of organic layers and bias in height accuracies here we present the application of direct push sensing techniques for minimal invasive geo archaeological surveys in zones affected by a high groundwater table especially when high resolution parameterization of buried geo archaeological structures is required two of these direct push applications are electrical conductivity logging and the measurement of colorimetric proxies in unconsolidated sediments the tools provide multi proxy information about layer structure texture and organic parameters the high sensing speed allows recording a large data set with high vertical and lateral resolution in this study we exemplary provide results of a buried canal structure within a valley in sw germany we present a high resolution cross section from a zone of high groundwater table the canal is part of charlemagne s summit canal fossa carolina an early medieval hydro engineering project bridging the central european watershed we compare the direct push sensing data with driving core samples and discuss prediction and generation options of parameter transfer from multiple one dimensional logs to a two dimensional canal cross section of high resolution in this context we use in situ obtained colorimetric data and electrical conductivity as proxies for geo archaeological site characterization we model organic fills of the canal by direct push logs and robust sediment data given the cost and time effectiveness of such tools geo archaeological site information of high depth accuracy was grown rapidly compared to less densely performed drillings that require an additional high effort in laboratory analyses the carolingian excavation depth is 6 m below current surface there is evidence for multiple organic layers in the trench fills which reveal aquatic to semi terrestrial stillwater deposition and therefore evidence of multiple carolingian and post carolingian ponds we have evidence for a conceptual width of the deep buried artificial water course of at least 3 4 m this allows a passage of carolingian cargo scows with a payload of several tons in this central zone of the canal

geologic section through the samail ophiolite and associated rocks along a muscat ibra transect southeastern oman mountains regional mapping at a 1 60 000 scale of a 30 km strip from the gulf of oman muscat across the oman mountains 130 km to the south provides the geologic setting for the 95 m y ibra section of the samail ophiolite where best preserved the ibra ophiolite section is an 8 km thick section of oceanic consisting of 0 5 km of pillow lavas 1 2 1 6 km of sheeted diabase dike complex 0 2 1 0 km of high level noncumulate gabbro and 3 0 5 0 km of cumulate gabbro that is underlain by tectonite peridotite 9 12 km thick the ibra section is found on the southward dipping limb of the sayah hatat antiform the tectonite peridotite represents uniformly depleted harzburgite and dunite that have been deformed by high temperature low stress asthenospheric flow discordant dunites within the tectonite peridotite appear to represent either flow crystallization products from primary picritic liquids or reaction products of these liquids with the harzburgite the structural base of the tectonite peridotite is overprinted by a high stress low temperature deformation that can be related to its oceanic detachment the layered gabbros are predominantly olivine clinopyroxene plagioclase cumulates and orthopyroxene does not occur as a cumulus phase occurrence of cumulate wehrlites and picrites at high stratigraphic levels within the layered gabbros is evidence that the gabbroic section crystallized predominantly from the bottom upward in a periodically replenished magma chamber high level gabbro represents remnants of crystallization at the roof of the magma chamber and intrudes most overlying diabase dikes both the diabase dike complex and pillow lavas are hydrothermally altered and alteration and metamorphism increase downward zeolite to epidote amphibolite facies in spite of pervasive alteration relict primary mineralogy and bulk chemistry suggest that the diabase dikes and pillow lavas are cogenetic with the underlying gabbros the present day samail thrust surface truncates ophiolite stratigraphy and puts the samail ophiolite on top of unmetamorphosed hawasina melange the last motion on this surface was probably no older than maestrichtian 70 65 m y garnet amphibolites exposed as remnants of earlier thrusting 90 m y record initial ophiolite detachment at a 14 20 km depth within the tethyan oceanic lithosphere the hawasina group which underlays the samail ophiolite is a block melange where exposed near muscat in the north and it grades into an imbricated broken formation at the southern limit of the map area the hawasina group is thrust over permian to late cretaceous shelf carbonates that represent autochthonous arabian continental shelf deposits recent post miocene collapse and dome structures such as the ibra dome have complicated ophiolite stratigraphy south of jabal dimh our geologic studies strongly indicate the samail ophiolite represents a large coherent slab of transported oceanic lithosphere formed at a late cretaceous spreading center in the tethyan sea

k ar ages of metamorphic rocks at the base of the samail ophiolite oman hornblendes from amphiobolities in the sheet of metamorphic rocks beneath the peridotite member of the samail ophiolite and phyllites farther from the peridotite contact have weighted mean sup 40 ar sup 39 ar total fusion ages of 90 0 3 0 m y and 79 5 3 0 m y respectively the amphibolities represent the first tectonic slice welded to the base of the samail ophiolite after it was detached from the tethyan oceanic crust formation of the amphiobolities occurred no more than 3 to 7 m y after crystallization of plagiogranite in the ophiolite the phyllites represent another tectonic slice of ocean floor sediments welded to the ophiolite as it was transported further from the tethyan spreading axis the k ar ages suggest assuming a half spreading rate of 2 to 5 cm yr that detachment of the samail ophiolite and formation of amphibolite facies rocks occurred no more than 60 to 350 km from spreading center using the same spreading rate one can calculate a minimum half width of 300 to 750 km for the tethyan ocean during the late cretaceous

a multidisciplinary approach in wetland geoarchaeology survey of the missing southern canal connection of the fossa carolina sw germany abstract in this manuscript we document a multidisciplinary approach in wetland geoarchaeology for detecting artificial structures in a middle european floodplain by means of a large set of different prospection methods cadastral analysis aerial archaeology lidar squid based magnetic prospection electrical resistivity tomography seismic refraction tomography ground penetrating radar and a subsequent geoarchaeological drilling campaign we provide an overview about the potentials and limits of the applied methods our site specific aims focus on the fossa carolina charlemagne s shortcut for linking the rhine main and the altmuhl danube inland navigation systems during the early middle ages our results show that altmuhl meander loops were quasi stable since carolingian times and that an altmuhl floodplain crossing trench of at least 650 700 m was required for linking the altmuhl river with the archaeological known southernmost position of the existing carolingian canal however our large set of remote sensing and geophysical prospection tools and the corresponding drilling campaign do not show any evidence for the missing carolingian trench within the altmuhl floodplain our results support the idea that the carolingian canal was never entirely completed although large parts of the canal were almost finished in the northern sections

ophiolites as indicators of the geodynamic evolution of the tethyan ocean abstract reviewing the ophiolites of the alpine chain from the western mediterranean to the indian ocean we subdivide them into ten groups of outcrops the geological environment through time the internal composition and history are given for each emphasis is put on the variegated and successive geodynamic processes which can be reconstructed for the different ophiolitic belts since their birth as an ocean like crust to their incorporation through accretion to a continent one can distinguish low versus high tholeiitic partial melting fairly or poorly established ridges simple ridge type crust versus complex ridge ensimatic arc and even more complex type long lived versus short lived oceanic crust stages abrupt large scale pure obduction versus progressive collision related obduction or simple progressive juxtaposition to continent the major events through time in the tethyan ophiolitic belts can be listed as follows spreading ridge activity during the jurassic liguria dinaro hellenides lesser caucasus and the cretaceous peri arabic nain sabzewar with a jump of ridge in between repeated change from ridge to ensimatic arc dinaro hellenic lesser caucasus peri arabic west indian during the latest jurassic and cretaceous upper cretaceous tertiary collision related obductions pontic lesser caucasus liguria squeezing out the elevated portions of these basins lack of oceanic magmatism during the cenozoic but progressive accretion along accretionary wedges of the elevated portions of the remaining mesozoic crust van nain sabzewar zahedan mekran

k ar dating of some infra ophiolitic metamorphic soles from the eastern mediterranean new evidence for oceanic thrustings before obduction abstract k ar dating on separated minerals from the infra peridotitic metamorphic soles outcropping beneath various eastern mediterranean ophiolite complexes pindos nappe in greece lycian antalya beysehir hoyran mersin and pozanti karsanti nappes in the taurides belt turkey baer bassit nappe in syria shows that the main metamorphic recrystallization of those rocks occurred 25 30 m y prior to the tectonic emplacement of the ophiolite complexes onto a continental platform these data support the hypothesis of an early slicing of the oceanic crust before its obduction advocated recently by several authors

geological constraints on the alpine evolution of the mediterranean tethys abstract the geological data on the mediterranean chains and basins are used to point out the constraints that they put on the location through time of oceanic versus continental lithosphere and on the successive relations between them emphasis is put on the rules and conventions which enable us to interpret the geological data in terms of plate tectonics and on the major disputed points for which a solution must be chosen in the first part the location of oceanic versus continental lithosphere is dealt with using the data on the present day basins the ophiolites and the subduction processes a neogene age is retained for the western mediterranean and the surrounding continental blocks are considered to have been previously a part of iberia a cretaceous age is retained for the eastern mediterranean apulia is considered as a part of the african plate except for this period the black sea is considered as a back arc basin formed mostly during the upper cretaceous the ophiolites are used to locate the mesozoic oceans for the double ophiolitic belts of the dinaro hellenides and the taurides the tectonic interpretations which minimise the number of oceanic basins have been retained for the kirsehir block of turkey the chosen solution locates a jurassic ocean to the north and makes it disappear when a cretaceous ocean opens to the south data on the subduction processes added to the information on these basins and led us to consider as oceanic the unknown basements of the carpathian flysch and the maghrebian flysch basins the second part deals with the organisation of basins and platforms emphasising the chronology of their formation and subsequent crushing it furnished step by step constraints on the tectonic history of the system which is related to plate displacement the general pattern derived from these data shows a wedge shaped tethyan ocean which disappeared mostly through repeated subduction below the eastern part of its northern margin the jurassic stage shows westward extension of the ocean between the eurasian and african plates and ends with the dinaro hellenic obduction the cretaceous stage shows a complete reorganisation including individual displacement of the iberian apulian and kirsehir sub plates the tertiary stage shows the general collision between the renewed eurasian and african plates and neogene subduction of the basins which avoided collision

triassic magmatism of the dinarides in yugoslavia abstract the triassic magmatism of the dinarides had a polyphase character it took place during a period of about 50 ma during the initial stages of the mesozoic wilson cycle their earliest phases might have been connected with rifting processes and the subsequent ones preceeded directly the opening of the dinaridic part of the tethys and the formation of a spreading ridge the triassic magmatism is represented by basic and more commonly by intermediate and acid plutonic and volcanic rocks with calc alkaline affinity the triassic magmatic rock association can be correlated on major element evidence with calc alkaline rocks of recent convergent plate margins however field relationships and the data on immobile trace elements indicate that lavas poured out over triassic sediments on a carbonate platform which was underlain by rocks of the continental crust the basic diversity of the triassic magmatism of the dinarides was influenced by partial melting other processes crystallization contamination and others must have played a secondary role

large scale strike slip displacement of the drauzug and the transdanubian mountains in early alpine history evidence from permo mesozoic facies belts abstract both the drauzug italy austria and the transdanubian mountains hungary show great differences in facies compared to the geological units that presently surround them i e proximal facies contrast with distal facies in the permo triassic lower liassic strata in the drauzug and the transdanubian mountains indicate an extensional regime causing typical structural features such as tilted blocks fault scarps and drowned carbonate platforms the permo mesozoic facies zones provide markers for the paleogeographic fitting of the drauzug and the transdanubian mountains with areas today lying some 300 400 km to the west the drauzug corresponds to the lombardian basin and the westernmost part of the northern calcareous alps while the transdanubian mountains correspond to the westernmost part of the lombardian basin the trento platform and the belluno trough the drauzug and the transdanubian mountains together with the south alpine realm were displaced to the east along strike slip faults during the middle jurassic to early cretaceous opening of the central atlantic and ligurian piemont oceans and the simultaneous subduction of the vardar ocean at the eastern margin of apulia finally in late oligocene and miocene times the southern alps were displaced back to the west along the dextral periadriatic fault system

geological characterisation of the settlement of villasviejas del tamuja caceres spain abstract a geological study of the settlement of villasviejas del tamuja was carried out with the aim of identifying the characteristics of its geological basement based on electrical tomography of the different profiles at different depths correlating the results of the electrical sections with the geological information of the outcrops it has been possible to establish the boundary between the archaeological and geological layer and to describe the changes in the lithology in depth the slate substrate with resistivity values of 200 m is at a depth between 1 and 3 m from an approximate depth of 7 m the resistivity increases due to the presence of a compositionally discordant unit with the slate substrate which may be a granite intrusion the progressive increase in resistivity values would be related to a contact aureole produced by the granitic intrusion with the development of hornfels that have been observed in the tamuja river bed this intrusion has also served to reveal evidence of mining in the area around the settlement this study has contributed towards defining the geometry of the original slate substrate as a condition of its initial settlement and development as well as providing in depth geological knowledge by providing electrical tomography with a good description of lithological changes with these data the geological knowledge of the study area is covered both in surface and in depth allowing for future research

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

landscape reconstruction and major flood events of the river main hesse germany in the environs of the roman fort at groβkrotzenburg abstract detailed geoarchaeological studies were conducted at the gro krotzenburg floodplain southern hesse germany in order to reconstruct the fluvial palaeogeography and search for roman harbour installations another objective was to reconstruct the local flood history based on stratigraphic and geochronological data prospection based on electrical resistivity tomography vibracoring and direct push electrical conductivity logging were carried out to detect and analyze subsurface stratigraphies altogether 6 sediment cores up to 7 m long were drilled along transects along and perpendicular to the present course of the river main based on sedimentological and geochemical data we classified four sedimentary units vibracore data helped to detect the pre holocene bedrock topography and to differentiate between sedimentary facies we present geophysical sedimentary and geochronological evidence of a river channel right in front of the roman fort that was probably active during roman times moreover we found another bridge pier candidate in the prolongation of a well documented roman bridge our findings further indicate that the northern riverbank has shifted towards south since roman times however neither sedimentary nor archaeological evidence for harbour installations could be brought to light nevertheless we assume that conditions favorable of a river harbour namely permanent water flow and sufficient water depth were guaranteed in front of the fort where an undercut slope was probably already existing during roman times several sequences of coarse grained sandy to gravelly river deposits were found associated with major flood events that affected the site at gro krotzenburg during late medieval and modern times at that time central germany was repeatedly influenced by extreme meteorological conditions and associated extreme runoff events based on radiocarbon data we were able to define two periods of major flooding namely between 1435 and 1484 cal ad and 1646 1792 cal ad these periods are contemporaneous with periods of increased flood frequency in central europe derived from historical sources namely 1430 1460 ad and 1730 1790 ad based on sedimentary and geo chronostratigraphic evidence major flood events detected at the gro krotzenburg alluvial plain are most probably related with the ad 1480 ad 1573 and ad 1780 events known from historical records our results document that few historical flood events controlled the overall development of the fluvial landscape at gro krotzenburg at least since roman times until the late 19th century namely by eroding pre existing fluvial deposits accumulating thick sequences of event deposits and narrowing the riverbed since the late 19th century river regulation measures severely changed the hydrological conditions of the river main

atlantic forcing of western mediterranean winter rain minima during the last 12 000 years abstract the limited availability of high resolution continuous archives insufficient chronological control and complex hydro climatic forcing mechanisms lead to many uncertainties in palaeo hydrological reconstructions for the western mediterranean in this study we present a newly recovered 19 63 m long core from lake sidi ali in the north african middle atlas a transition zone of atlantic western mediterranean and saharan air mass trajectories with a multi proxy approach based on magnetic susceptibility carbonate and total organic c content core scanning and quantitative xrf stable isotopes of ostracod shells charcoal counts cedrus pollen abundance and a first set of diatom data we reconstruct western mediterranean hydro climatic variability seasonality and forcing mechanisms during the last 12 000 yr a robust chronological model based on ams 14 c dated pollen concentrates supports our high resolution multi proxy study long term trends reveal low lake levels at the end of the younger dryas during the mid holocene interval 6 6 to 5 4 cal ka bp and during the last 3000 years in contrast lake levels are mostly high during the early and mid holocene the record also shows sub millennial to centennial scale decreases in western mediterranean winter rain at 11 4 10 3 9 2 8 2 7 2 6 6 6 0 5 4 5 0 4 4 3 5 2 9 2 2 1 9 1 7 1 5 1 0 0 7 and 0 2 cal ka bp early holocene winter rain minima are in phase with cooling events and millennial scale meltwater discharges in the sub polar north atlantic our proxy parameters do not show so far a clear impact of saharan air masses on mediterranean hydro climate in north africa however a significant hydro climatic shift at the end of the african humid period 5 ka indicates a change in climate forcing mechanisms the late holocene climate variability in the middle atlas features a multi centennial scale nao type pattern with atlantic cooling and western mediterranean winter rain maxima generally associated with solar minima

the biostratigraphy of sediments in the volcanic unit of the samail ophiolite sedimentary rocks of pelagic and ocean ridge affinity interbedded with or overlying the volcanic sequence at the top of the oman ophiolite contain datable radiolarian faunas that indicate 1 that the lavas were erupted in an oceanic environment during a narrow time interval ranging from the early cenomanian to the early turonian and 2 that the age progression within this volcanic sequence matches its development from a ridge axis to an off axis setting emplacement of the ophiolite has been dated as late campanian early maestrichtian glennie et al 1974 thus the time gap between formation and emplacement was very narrow

visualization of lidar derived relief models for detection of archaeological features abstract this paper presents visualisation techniques of high resolution digital elevation models dems for visual detection of archaeological features the methods commonly used in archaeology are reviewed and improvements are suggested one straightforward technique that has so far not been used in archaeology the shift method is presented the main purpose of this article is to compare and evaluate different visualisation methods two conclusions have been reached where a single method must be chosen for printing or producing digital images for non professionals the use of sky view factor or slope gradient is endorsed both presented in greyscale otherwise interpreters should choose different techniques on different terrain types shift on flat terrain sky view factor on mixed terrain slope gradient on sloped terrain and sky view factor preferably as a composite image with slope gradient on rugged terrain

tectonic history of the western tethys since the late triassic the tectonic history of the western tethys since the late triassic is illustrated through a set of computer generated plate reconstructions which are based on a rigorous plate motions model of this region the model is constrained by the atlantic plate kinematics and on land geologic evidence and defines 13 tectonic phases spanning the time interval from the late ladinian 230 ma to the present the kinematics associated with the late triassic western tethyan rifts produced the detachment of a large composite fragment from the northern margin of gondwana it can be considered as the eastern propagation of the central pangea breakup during the early jurassic these rift zones became inactive while new zones of extension formed along the southern margin of eurasia the eastern margin of iberia and within the rifted northern gondwana fragment itself plate motions associated with the first two extensional centers can still be considered as an eastern branch of the central atlantic plate kinematics conversely the kinematic parameters of the latter rift result from the composition of the euler rotation describing the central pangea breakup and the euler pole of closure of the paleo tethys ocean the late triassic early jurassic rifting phases determined the formation of a number of independent microplates at the interface between africa and eurasia starting from the early cretaceous convergence between africa and eurasia triggered further deformation within the dispersed continental fragments and the formation of backarc basins at the active margins ultimately leading to an increase in the number of tectonic elements that were moving independently in the western tethyan region during the late cretaceous and the cenozoic the proposed tectonic evolution of the western tethys area is compatible with both global scale plate kinematics and geological constraints from on land data observed across the present day mosaic of displaced terranes surrounding the mediterranean region

changes in paleocurrents during the development of an obliquely convergent plate boundary sulaiman fold belt southwestern himalayas west central pakistan abstract pre orogenic cretaceous shelf sandstones at the northern and southern ends of the sulaiman range in west central pakistan show basically westward dispersal which is off the craton however paleocene marine sandstones in the south spread east southeast and early eocene deltaic sandstones in the north spread southeast and north these are mostly onto the craton and indicate slope reversal of the cretaceous shelf post oligocene fluvial molasse shows mostly southward drainage a 3852 m section of molasse in the northern sulaiman range comprises a lower 2378 m of claystones and upwardly fining sandstones that represent meandering rivers and an upper 1474 m that are dominated by conglomerates that represent gravelly braided rivers paleocurrents in the lower meandering part of the section were generally southward but very variable whereas those in the upper braided part were more uniform and show eastward flow a 3146 m section of molasse in the southern sulaiman range comprises 1 a basal 1160 m sequence of claystones and sandstones meandering streams with very diverse flow directions overall to the southwest 2 a middle 1603 m sequence dominated by pebbly sandstone with large bedforms big sandy braided rivers with less diverse flow to the southwest and 3 an upper 383 m conglomeratic sequence gravelly braided streams that still flow uniformly southwest rivers in the early molasse paralleled the modern sulaiman range in the north and flowed obliquely into it in the south which suggests no uplift of the modern front of the range until the onset of modern transverse eastward drainage and the associated influx of conglomerates in present and admittedly uncertain lithostratigraphic terms uplift of the modern front of the range apparently began about 700 m lower in the north than in the south the northern and southern molasse sections otherwise show broadly similar histories of river development

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

lidar derived high resolution palaeo dem construction workflow and application to the early medieval lower rhine valley and upper delta abstract reconstruction of past topography in palaeo dems serves various geomorphological analyses constructing a palaeo dem by stripping young elements from a lidar dem can provide results for large study areas at high resolution however such a top down approach is more suited to recent periods and geomorphologically static parts of the landscape than to geomorphologically dynamic areas and periods farther back in time here we explore this approach by reconstructing the early medieval circa 800 ce topography of the lower rhine river valley and upper delta in germany and the netherlands the large 4500 km2 study area contains abundant anthropogenic terrain modification and stretches across geomorphologically active as well as inactive zones we first removed all anthropogenic relief elements from the lidar dem using separate procedures for linear and non linear elements these steps were sufficient to obtain the palaeotopography of the inactive zone characterized by inherited natural relief then we reconstructed the topography and bathymetry in the fluvially reworked active zone by incorporating geological and historical geographical information we present and evaluate zonal averages of elevation differences between the modern and past valley floor topography in this densely populated area with complex land use history which allows us to approximate total anthropogenic volumetric change further comparisons with the modern lidar dem elucidate changes in floodplain negative relief connectivity showing the potential importance of investing in palaeo dems when assessing past river flooding our palaeo dem construction workflow is deployable at diverse spatial scales and widely applicable to other lowland areas because of its top down and generic nature the relative importance of different workflow aspects depends on the time period that is targeted beyond a target age of 10 15 ka valley floors that are too large in area are to be considered geomorphologically dynamic and the top down approach to palaeo dem construction is no longer advisable

fission track evidence for late triassic oceanic crust in the french occidental alps five zircons and one apatite from plutonic rocks of the ophiolitic sequence from the piemontese zone western alps southeast france have been dated by the fission track method the ages obtained indicate that the minimum age of the alpine oceanic crust in this zone is between 192 6 and 212 8 m y late triassic liassic consideration of the available data on fission track retention conditions in zircons and pressure temperature conditions allowed by the high pressure mineralogic assemblages of the rocks leads to the conclusion that in the external part of the piemontese zone the temperature duration conditions of the high pressure alpine metamorphism were inadequate to significantly reset the zircons9 fission track clock suggesting a short lived metamorphic event

a stratigraphic framework for abrupt climatic changes during the last glacial period based on three synchronized greenland ice core records refining and extending the intimate event stratigraphy due to their outstanding resolution and well constrained chronologies greenland ice core records provide a master record of past climatic changes throughout the last interglacial glacial cycle in the north atlantic region as part of the intimate integration of ice core marine and terrestrial records project protocols have been proposed to ensure consistent and robust correlation between different records of past climate a key element of these protocols has been the formal definition and ordinal numbering of the sequence of greenland stadials gs and greenland interstadials gi within the most recent glacial period the gs and gi periods are the greenland expressions of the characteristic dansgaard oeschger events that represent cold and warm phases of the north atlantic region respectively we present here a more detailed and extended gs gi template for the whole of the last glacial period it is based on a synchronization of the ngrip grip and gisp2 ice core records that allows the parallel analysis of all three records on a common time scale the boundaries of the gs and gi periods are defined based on a combination of stable oxygen isotope ratios of the ice 18o reflecting mainly local temperature and calcium ion concentrations reflecting mainly atmospheric dust loading measured in the ice the data not only resolve the well known sequence of dansgaard oeschger events that were first defined and numbered in the ice core records more than two decades ago but also better resolve a number of short lived climatic oscillations some defined here for the first time using this revised scheme we propose a consistent approach for discriminating and naming all the significant abrupt climatic events of the last glacial period that are represented in the greenland ice records the final product constitutes an extended and better resolved greenland stratotype sequence against which other proxy records can be compared and correlated it also provides a more secure basis for investigating the dynamics and fundamental causes of these climatic perturbations

the history of soil erosion and fluvial deposits in small catchments of central europe deciphering the long term interaction between humans and the environment a review abstract during the last few decades many case studies focused on the dynamics of fluvial systems in response to hillslope erosion land use impact and climate changes this paper will review the current state of knowledge of the dynamics of past soil erosion and gullying in small catchments

global tectonics since the breakup of pangea 180 million years ago evolution maps and lithospheric budget abstract pangea the earth s youngest single supercontinent broke up 180 million years ago tectonic plates were subsequently formed by dispersal of the continental fragments and accretion of new oceanic lithosphere the configurations of all the major lithospheric plates at 0 20 65 95 140 180 ma bp are reconstructed on six globes of the earth each with a radius of 10 cm it appears that plate boundaries maintain a remarkably close fit on model globes of constant radii if the reconstructions include the recovery of subducted spreading patterns this is illustrated with maps in equatorial orthographic oblique orthographic and transverse hammer aitoff projections the snug fit of the tectonic plates at every tested time since the breakup of pangea 180 ma bp is consistent with the theory of plate tectonics on a non expanding earth and contradicts rapidly expanding earth models the areas of oceanic lithosphere produced and consumed during the past 180 ma bp are estimated from surface measurements of the globes reconstructed on the basis of particular assumptions these measurements suggest a consistent increase in the production rate of oceanic lithosphere during the past 140 ma it was decided to revise the assumptions and see if alternative reconstructions of the ancient spreading patterns on the floors of the tethys and eo pacific oceans could avoid implying an increase of lithospheric production rates with time this appeared to be possible the revised maps suggest that ophiolites older than 180 ma bp may have been obducted in cenozoic collision zones of the himalayas andes rockies and the western part of the banda arc timor new guinea estimates of the ocean floor production and consumption budget appear to be quite similar for both map series and only the possible ranges are summarized here time averaged for the past 180 ma world wide production and consumption of oceanic lithosphere appears to have varied between 2 6 and 3 5 km2 a 1 at most the mean of world wide spreading velocities ranges between 2 4 and 3 5 cm a 1 and world wide means of subduction velocities lie between 4 2 and 6 3 cm a 1 more accurate estimates are possible on the basis of particular assumptions and have been specified for the various time intervals distinguished i e the neogene 0 20 ma bp palaeogene 20 65 ma bp upper cretaceous 65 95 ma bp lower cretaceous 95 140 ma bp and middle and upper jurassic 140 180 ma bp

tectonics and geology of spreading ridge subduction at the chile triple junction a synthesis of results from leg 141 of the ocean drilling program an active oceanic spreading ridge is being subducted beneath the south american continent at the chile triple junction this process has played a major part in the evolution of most of the continental margins that border the pacific ocean basin a combination of high resolution swath bathymetric maps seismic reflection profiles and drillhole and core data from five sites drilled during ocean drilling program odp leg 141 provide important data that define the tectonic structural and stratigraphic effects of this modern example of spreading ridge subduction a change from subduction accretion to subduction erosion occurs along strike of the south american forearc this change is prominently expressed by normal faulting forearc subsidence oversteepening of topographic slopes and intensive sedimentary mass wasting overprinted on older signatures of sediment accretion overthrusting and uplift processes in the forearc data from drill sites north of the triple junction sites 859 861 show that after an important phase of forearc building in the early to late pliocene subduction accretion had ceased in the late pliocene since that time sediment on the downgoing oceanic nazca plate has been subducted site 863 was drilled into the forearc in the immediate vicinity of the triple junction above the subducted spreading ridge axis here thick and intensely folded and faulted trench slope sediments of pleistocene age are currently involved in the frontal deformation of the forearc early faults with thrust and reverse kinematics are overprinted by later normal faults the chile triple junction is also the site of apparent ophiolite emplacement into the south american forearc drilling at site 862 on the taitao ridge revealed an offshore volcanic sequence of plio pleistocene age associated with the taitao fracture zone adjacent to exposures of the pliocene aged taitao ophiolite onshore despite the large scale loss of material from the forearc at the triple junction ophiolite emplacement produces a large topographic promontory in the forearc immediately after ridge subduction and represents the first stage of forearc rebuilding

structure and evolution of the passive margin of the eastern tethys abstract an extensive passive margin was formed in the triassic along the periphery of arabia including the tauric carbonate platform this event is related to the opening of the mesozoic tethys when a number of microcontinents split off from gondwana triassic extension and continental rifting resulted in the formation of a structural pattern which is uniform from the dinarides to oman it includes the following elements 1 1 shelf 2 2 continental slope 3 3 deep basin probably with a floor of attenuated sialic crust 4 4 inner carbonate platform in the jurassic cretaceous stable conditions prevailed influenced only by eustatic oscillations of the sea level turbidites accumulated on the continental rise while cherts and radiolarites were deposited in the deep basins hawasina pichakun antalya pindus below the ccd level sedimentation on the shelf was controlled by north northeast transverse tectonic elements which also continued across the passive margin dividing it into a number of segments collision with an island arc led to obduction of the oceanic crust deformation of the passive margin and overthrusting of its sedimentary cover onto the arabian shelf obduction and deformation lasted for about 10 m y and created a new tectonic pattern with concentric structural zones surrounding the arabian promontory these zones include 1 1 the flysch basin a remnant of the closing tethys 2 2 an uplift a site of periodical emergence and erosion corresponding to the frontal part of the ophiolitic nappes 3 3 the border furrow a depocenter of low energy calcareous marls 4 4 the arabian shield constantly emerged during the tertiary tectonic deformation of these zones caused by the collision of arabia with eurasia began prior to the early miocene and it is still going on data on afghanistan demonstrate that its central part the gelmend argandab and kabul blocks belonged during the paleozoic and early mesozoic to the continental shelf of india

variable bottom water in the western mediterranean basin the deep water of the western mediterranean has long been considered to have practically constant values of s and between 1909 1910 the thor expedition and the 1970 cruise of the jean charcot the deep water at more than 1800 m depth showed very little variation the small changes which appeared through the years could be due in part to changes in instrumentation analysis and methods of sampling in 1972 and 1973 during the medoc cruises a bottom layer of 200 300 m thickness was found its temperature and salinity showed a small gradient producing at the bottom an increase of potential temperature of about 0 01 to 0 02 c and an increase in salinities of about 0 010 00 relative to a minimum of and s in the deep water at 1800 2000 m these minima of and s were found to be homogeneous horizontally at all stations occupied in the medoc area and in the ligurian sea in 1973 interestingly the bottom layer was not present in 1974 however in november 1981 during the cruise mediprod iv the variable bottom water was again present extending from the ligurian sea and medoc areas along the western coasts of corsica and sardinia to the eastern alboran sea in most cases the maximum values of and s were recorded at the bottom and were higher than the 1973 values by about 0 03 c and up to 0 0150 00 but with a rather high spatial variability by february 1982 cruise dyome ii the situation had become more complicated not only was a layer of minimum and s present but it was underlain by a layer of maximum and s below which a decrease appeared producing a new minimum at the very bottom in addition a number of stations displayed higher values of by about 0 05 c and of s by about 0 0150 00 in the layers of minimum and maximum characteristics as well as on the bottom in contrast to the situation in 1973 high spatial variability was found in the deep layering the variability may have been due to patchy deep convention activity possibly in the ligurian sea the phenomenon of variable bottom water and the processes which produce it may be relevant to our understanding of water mass formation

upper cretaceous plate rupture and development of leaky transcurrent fault ophiolites in southeast turkey abstract field observations in the thrust fault belt in southeastern turkey reveal two contradictory relationships regarding the existence of the turkish microplate and the southern tethys jurassic and early cretaceous sediments on the platforms of the turkish and arabian plates can be correlated this weakens the hypothesis that the turkish plate was separated from africa in the triassic on the other hand stratigraphic relationships on slivers of continental crust between ophiolite strips do not allow the ophiolites north and south of such continental blocks to be linked this necessitates postulating the previous existence of distinct oceanic basins between the continental slivers the ophiolites in southeastern turkey are of upper cretaceous age the separation of the turkish microplate and the generation of southern tethys in southeastern turkey did not take place in triassic times but in the late cretaceous plate rupture was probably caused by a major change in plate motions 80 m y ago the turkish plate was completely sheared off the northern edge of africa by northeasterly trending transcurrent faults through southeastern turkey mantle leakage along such transcurrent faults must have generated the ophiolites of the thrust fault belt of south eastern turkey in narrow ocean basins between ribbons of continental crust