worldwide initiation of holocene marine deltas by deceleration of sea level rise radiocarbon dated deltaic sequences of holocene age from different parts of the world began to accumulate within a restricted time range from about 8500 to 6500 years ago evaluation of major delta processes indicates that deceleration in sea level rise was the key factor in holocene delta formation within many deltas there is as much as a 2000 year age range between basal deposits in seaward and landward cores this age difference records the progressive landward migration of near mean sea level depositional environments during the lower to mid holocene establishment of a chronostratigraphic framework for holocene delta development provides a fundamental global baseline for distinguishing sea level change from vertical land motion by tectonism and isostasy and for evaluating rates of future marine incursion into low lying deltas

the younger dryas main line on leka norway as determined from a high resolution digital elevation model derived from airborne lidar data abstract the main line is a conspicuous late glacial erosive feature along parts of the norwegian coastline although the shoreline has been much studied the genesis of the ancient raised sea level is still somewhat unaccounted for in this study the main line on leka norway is illuminated through a high resolution 1 m pixel size digital elevation model dem derived from airborne lidar data the dem allows a detailed mapping of the shoreline s dimensions and actual distribution and hence provides an improved foundation for interpreting the pronounced features a new method for estimating cliff degradation during shoreline formation is presented the main line is found from 106 112 m asl on leka varying platform morphology across the island points to different shore eroding mechanisms the shoreline is thought to be developed through the interaction of sea ice processes and freeze thaw mechanisms where the former agent is considered to be of particular importance where the platforms are most levelled a bulge on the outermost part of the shoreline features is described for the first time and interpreted as a consequence of freeze on plucking mean platform widths range from 9 29 m while mean cliff degradation is estimated to be 140 m3 m 1 by adapting the age span of main line formation reported elsewhere maximum erosion rates over 1 ma totals to 58 km the study sheds light on the main line s potential as a reference level when assessing postglacial landscape development and highlights the significance of episodic erosional events in cold climate regimes

geo archaeological evidence for a holocene extreme flooding event within the arabian sea ras al hadd oman abstract the arabian sea is regarded as one of the least studied regions in terms of coastal hazards such as tropical cyclones and tsunamis parts of the coastline are developing rapidly especially in oman this calls for a proper understanding of the natural processes that act on and affect it this can be done by investigating the magnitude and impact of past events in particular on human settlements by doing this future risks may not only be scientifically predicted and evaluated but the damage caused by future events might even be mitigated evidence of past extreme wave events is preserved in the onshore stratigraphic record in addition to this the coastal zone of oman is rich in archaeological remains presented here are the results of comprehensive mapping and analysis of extreme wave deposits of an archaeological site near ras al hadd suggesting that the early bronze age site hd 6 was inundated at 4450 cal bp an event layer is identified between two settlement phases within the archaeological excavation a contemporaneous sand bed with a maximum thickness of 0 4 m was mapped in the vicinity of the settlement ground penetrating radar surveys allow measurement of the thickness as well as identification of the internal facies architecture of the deposit a high resolution digital elevation model reveals the coastal geomorphology it is concluded that the causative event must have been a tsunami that was most likely generated within the makran subduction zone this interpretation does however remain tentative at the moment archaeological evidence indicates that the site was immediately re occupied after the event which attests to a certain resiliences of the early bronze age coastal communities in the region

isostatic uplift driven by karstification and sea level oscillation modeling landscape evolution in north florida isostatic uplift of tectonically stable passive margin lithosphere can preserve a record of paleo shoreline position by elevating coastal geomorphic features above the influence of nearshore wave activity conversely depositional ages and modern elevations of these features can provide valuable information about the uplift history of a region we present a numerical model that combines sea level oscillation subaerial exposure a precipitation karstification function and isostatic uplift to explore the dynamic geomorphic behavior of coastal carbonate landscapes over multiple sea level cycles the model is used to estimate ages of coastal highstand depositional features along the atlantic coast of north florida numerical simulations using current best estimates for pleistocene sea level and precipitation histories suggest ages for trail ridge 1 44 ma the penholoway terrace 408 ka and the talbot terrace 120 ka that are in agreement with fossil evidence in addition model results indicate that the rate of karstification void space creation or equivalent surface lowering rate within the north florida platform is 3 5 times that of previous estimates 1 m 11 2 k y vs 1 m 38 k y and uplift rate is 2 times as high as previously thought 0 047 mm yr vs 0 024 mm yr this process has implications for landscape evolution in other carbonate settings and may play an underappreciated role within the global carbon cycle

the implications of revised quaternary palaeoshoreline chronologies for the rates of active extension and uplift in the upper plate of subduction zones we demonstrate a synchronous correlation technique to determine the chronology of quaternary palaeoshorelines to test proposed relationships between tectonics climate and sea level change the elevations of marine palaeoshorelines in calabria around the active vibo normal fault have been measured from tin dem 10 m data and fieldwork and correlated with global sea level curves a synchronous correlation method and new u th dates are used to ascertain how the slip rate on the fault relates to uplift rates across the region regional uplift possibly associated with subduction along the calabrian trench or due to the cumulative effect of closely spaced active normal faults is rapid enough to uplift even the hangingwall of the vibo normal fault the actual value for the rate of background uplift can only be ascertained once the rate of slip on the vibo fault is subtracted synchronous correlation of multiple palaeoshorelines sampled along 29 elevation profiles with global sea levels shows that the resultant uplift rate background uplift minus local hangingwall subsidence is constant through time from 0 to 340 ka and not fluctuating by a factor of 4 as previously suggested the uplift rate increases from 0 4 mm yr at the centre of the hangingwall of the fault to 1 75 mm yr in the hangingwall in the vicinity of the fault tip palaeoshorelines can be traced from the hangingwall to the footwall around the fault tip and hence correlated across the fault the throw rate on the fault averaged over 340 ka decreases from a maximum at the centre of the fault 1 mm yr to zero at the tip this gradient in throw rate explains the spatial variation in resultant uplift rates along the fault we interpret the 1 75 mm yr resultant uplift rate at and beyond the fault tip as the signature of a regional uplift presumably related to subduction although we cannot exclude the possibility that other local faults influence this uplift the lower uplift rates in the hangingwall of the fault are due to interaction between regional uplift and subsidence associated with the local active normal faulting we discuss a how our synchronous correlation technique should trigger a re appraisal of palaeoshoreline chronologies worldwide and b the implications for the tectonics and seismic hazard of calabria suggesting that perturbations in the uplift rate field are a key criterion to map the locations of active faults their deformation rates and hence seismic hazard above subduction zones

space geodetic constraints on glacial isostatic adjustment in fennoscandia analysis of global positioning system gps data demonstrates that ongoing three dimensional crustal deformation in fennoscandia is dominated by glacial isostatic adjustment our comparison of these gps observations with numerical predictions yields an earth model that satis es independent geologic constraints and bounds both the average viscosity in the upper mantle 5 x 10 20 to 1 x 10 21 pascal seconds and the elastic thickness of the lithosphere 90 to 170 kilometers we combined gps derived radial motions with fennoscandian tide gauge records to estimate a regional sea surface rise of 2 1 0 3 mm year furthermore ongoing horizontal tectonic motions greater than 1 mm year are ruled out on the basis of the gps derived three dimensional crustal velocity field

late quaternary deformation of marine terraces on the cascadia subduction zone near cape blanco oregon the cape blanco region of south coastal oregon sits on the upper plate of the cascadia subduction zone about 60 70 km east of the base of the continental slope though the region has no historic coseismic deformation late quaternary deposits and landforms show abundant evidence of uplift folding and faulting a set of five late quaternary marine terraces and one uplifted holocene beach berm are preserved in the cape blanco region stratigraphic and altitudinal surveys of these physiographic features combined with several numerical and correlation age determinations permit a reconstruction of tectonic deformation near cape blanco in approximately the last 200 000 years the most cogent aspects of the neotectonics in this part of the cascadia subduction zone are that an east west trending anticline deforms the lower three terraces 80 125 ka as well as accounting for uplift of the holocene storm berm latest movement on the anticline was no more than 2 000 years ago but the anticline also deforms sediments as old as middle miocene the anticline is consistent with a north south principal contraction axis at cape blanco in about the last 100 000 years an older terrace at cape blanco approximately 200 ka is offset by two reactivated faults whose movements prior to the eocene served to suture several terranes to the north american continent tectonic tilting in the older terrace is not consistent with a north south principle axis of contraction but the axis of tilt is parallel to north northwest striking structures developed in the quaternary fold belt offshore on the continental shelf the observed deformation indicates that regional stress in the vicinity of cape blanco in the late quaternary has been accommodated by a variable pattern of strain

drainage systems and the development of normal faults an example from pleasant valley nevada abstract drainage systems in regions of active extension contain information about fault zone structure and development and particularly about the lateral growth of individual fault segments that is difficult to obtain by more conventional means such as the dating of sedimentary material we investigate drainage fault interaction in pleasant valley nevada where a large normal faulting earthquake occurred in 1915 we find geomorphological evidence for a propagation increase in length of several km at both ends of one of the 1915 fault segments at one end we estimate the propagation rate to be about 50 m per earthquake this estimate is uncertain but is within the range predicted by theoretical models of fault growth drainage along the axes of half graben in this region may be influenced by the spacing of tilted fault blocks the highest valleys are also the narrowest whether the axial streams succeed in reaching lower neighbouring sinks depends on whether sedimentation rates are able to keep basins filled to the levels of the basement highs that separate half graben of opposite polarity a knowledge of modern drainage fault interactions may help predict drainage systems and the position of potential syn rift reservoir sediments in older extensional terrains where fault configurations but not facies distributions are known from seismic reflection surveys

differential uplift along the northern margin of the central anatolian plateau inferences from marine terraces abstract emerged marine terraces and paleoshorelines along plate margins are prominent geomorphic markers that can be used to quantify the rates and patterns of crustal deformation the northern margin of the central anatolian plateau has been interpreted as an actively deforming orogenic wedge between the north anatolian fault and the black sea here we use uplifted marine terraces across principal faults on the sinop peninsula at the central northern side of the pontide orogenic wedge to unravel patterns of quaternary faulting and orogenic wedge behavior we leveled the present day elevations of paleoshorelines and dated marine terrace deposits using optically stimulated luminescence osl to determine coastal uplift the elevations of the paleoshorelines vary between 4 0 2 and 67 1 4 m above sea level and osl ages suggest terrace formation episodes during interglacial periods at ca 125 190 400 and 570 ka corresponding to marine isotopic stages mis 5e 7a 11 and 15 mean apparent vertical displacement rates without eustatic correction deduced from these terraces range between 0 02 and 0 18 mm a with intermittent faster rates of up to 0 26 mm a we obtained higher rates at the eastern and southern parts of the peninsula toward the hinterland indicating non uniform uplift across the different morphotectonic segments of the peninsula our data are consistent with active on and offshore faulting across the sinop peninsula when integrated with regional tectonic observations the faulting pattern reflects shortening distributed over a broad region of the northern margin of the central anatolian plateau during the quaternary

a note of caution on the use of boulders for exposure dating of depositional surfaces abstract exposure dating of boulders has been widely applied to determine the age of depositional surfaces under the assumption that the pre depositional nuclide component in most boulders is negligible here we present a case study on fluvial terraces at the active mountain front of the eastern andes where this assumption is clearly invalid because sandstone boulders n 13 from terraces at two sites contain a highly variable inherited 10be component and have apparent 10be ages that exceed the age of the respective surface by up to 90 ka likewise boulders from active stream channels n 5 contain a substantial inherited 10be component equivalent to 5 48 ka of exposure the age of the fluvial terraces is well determined by two approaches that allow to correct for the pre depositional nuclide component 10be dating of amalgamated pebbles and 10be depth profiles on sand samples at site 1 three terraces have 10be ages of 3 5 ka t2 11 13 ka t3 and 16 20 ka t4 which are consistent with the terrace stratigraphy the age of terrace t3 is confirmed by a calibrated 14 c age of 12 61 0 20 ka bp obtained from a wood sample at site 2 terrace t3 has a 10be age of 13 16 ka the average inherited 10be concentration of sand grains determined from depth profiles and stream sediments is small and equivalent to 1 3 ka of exposure in contrast the mean inheritance of pebbles and boulders is higher and equivalent to exposure times of 10 ka and 30 ka respectively these differences in the pre depositional nuclide component are related to the different provenance and transport history of sand pebbles and boulders the sand is derived from rapidly eroding miocene sediments exposed near the mountain front whereas the pebbles and boulders originate from triassic sandstones in the internal part of the fold and thrust belt on their way to the mountain front boulders and pebbles were temporarily stored and irradiated in alluvial fans that are currently reworked as sediment deposition in intramontane basins and their subsequent excavation is common in the andes and other fold and thrust belts the presence of pre depositional nuclide components should be evaluated when applying exposure dating at active mountain fronts

active simultaneous uplift and margin normal extension in a forearc high crete greece abstract the island of crete occupies a forearc high in the central hellenic subduction zone and is characterized by sustained exhumation surface uplift and extension the processes governing orogenesis and topographic development here remain poorly understood dramatic topographic relief 2 6 km astride the southern coastline of crete is associated with large margin parallel faults responsible for deep bathymetric depressions known as the hellenic troughs these structures have been interpreted as both active and inactive with either contractional strike slip or extensional movement histories distinguishing between these different structural styles and kinematic histories here allows us to explore more general models for improving our global understanding of the tectonic and geodynamic processes of syn convergent extension we present new observations from the south central coastline of crete that clarifies the role of these faults in the late cenozoic evolution of the central hellenic margin and the processes controlling quaternary surface uplift pleistocene marine terraces are used in conjunction with optically stimulated luminesce dating and correlation to the quaternary eustatic curve to document coastal uplift and identify active faults two south dipping normal faults are observed which extend offshore offset these marine terrace deposits and indicate active n s margin normal extension further marine terraces preserved in the footwall and hanging wall of both faults demonstrate that regional net uplift of crete is occurring despite active extension field mapping and geometric reconstructions of an active onshore normal fault reveal that the subaqueous range front fault of south central crete is synthetic to the south dipping normal faults on shore these findings are inconsistent with models of active horizontal shortening in the upper crust of the hellenic forearc rather they are consistent with topographic growth of the forearc in a viscous orogenic wedge where crustal thickening and uplift are a result of basal underplating of material that is accompanied by extension in the upper portions of the wedge within this framework a new conceptual model is presented for the late cenozoic vertical tectonics of the hellenic forearc

tertiary quaternary faulting and uplift in the northern oman hajar mountains field mapping and remote sensing investigations reveal two new major fault sets cutting through tertiary rocks quaternary terraces and a several hundred year old irrigation canal system in the hajar mountains of northern oman they extend for tens of kilometres forming fracture intensification zones several hundred metres wide wnw to nw oriented faults run parallel to the mountain fronts in the plains adjoining the central hajar range then obliquely crosscut the mountains in the north motion along these faults explains how quaternary marine terraces became elevated 190 m above sea level a second fault set strikes north to nne the associated juvenile topography suggests that they also accommodate recent uplift subsidiary to the wnw striking faults with minor strike slip and differential movement between various segments of the hajar mountains both fault systems and the amount of quaternary uplift between 100 and 500 m are similar to those in other active and ancient forebulge environments using the fracture patterns observed it is proposed here that the hajar range lies on the active forebulge of a collision zone between the ne margins of the arabian plate the zagros fold belt and the makran accretionary prism which resulted in the recent uplift

styles and rates of long term denudation in carbonate terrains under a mediterranean to hyper arid climatic gradient abstract carbonate minerals unlike silicates have the potential to dissolve almost completely and with high efficiency thus in carbonate terrains denudation rate and style the governing process of denudation mechanical or chemical should be more sensitive to climatic forcing using 36 cl measurements in 39 carbonate bedrock and sediment samples we calculate long term denudation rates across a sharp climatic gradient from mediterranean to hyper arid conditions our samples were collected along the arugot watershed which drains the eastern flank of the judea range central israel to the dead sea and is characterized by a pronounced rain shadow denudation rates of flat lying bedrock outcrops sampled along interfluves differ by an order of magnitude from 20 mm ka 1 in the mediterranean zone to 1 3 mm ka 1 in the hyper arid zone these rates are strongly correlated with precipitation and thus reflect the importance of carbonate mineral dissolution in the overall denudation process in contrast denudation rates of steep bedrock surfaces depend on the hillslope gradient but only in the hyper arid climate zone indicating that mechanical processes dominate the overall hillslope denudation within this zone the dominance of slope dependent mechanical erosion in the hyper arid zone is also reflected by an increase in spatially average denudation rates from 17 19 mm ka 1 in the mediterranean semi arid zones to 21 25 mm ka 1 in the hyper arid zone these higher rates are attributed to clast contribution from steep slopes under arid climate this suggests an increased importance of mechanical processes to the overall denudation in the hyper arid zone we demonstrate that the transition between chemically dominated denudation to mechanically dominated denudation occurs between 100 and 200 mm of mean annual precipitation long term denudation rates across the judea range indicate that between mediterranean and hyper arid climates chemical weathering rates are limited by precipitation nevertheless in more humid climates chemical weathering rates are apparently limited by the rates of carbonate mineral dissolution this study demonstrates that carbonate terrains have the capacity to shift between mechanically and chemically dominated denudation in response to changes in precipitation similar transitions in response to changes in temperature or the level of tectonic activity have been previously reported we suggest that the abrupt nature of such transitions can be primarily attributed to the efficiency of carbonate dissolution processes and the competition between surface and subsurface drainage systems in carbonate terrains

age estimates and uplift rates for late pleistocene marine terraces southern oregon portion of the cascadia forearc marine terraces are prominent landforms along the southern oregon coast which forms part of the forearc region of the cascadia subduction zone interest in the cascadia subduction zone has increased because recent investigations have suggested that slip along plates at certain types of convergent margins is characteristically accompanied by large earthquakes in addition other investigations have suggested that convergent margins can be broadly classified by the magnitude of their uplift rates with these hypotheses in mind we generated new uranium series amino acid and stable isotope data for southern oregon marine terrace fossils these data along with terrace elevations and two alternative estimates of sea level at the time of terrace formation allow us to determine terrace ages and uplift rates uranium series analysis of fossil coral yields an age of 83 5 ka for the whisky run terrace at coquille point in bandon oregon a combination of amino acid and oxygen isotope data suggest ages of about 80 and 105 ka for the lowest two terraces at cape blanco these ages indicate uplift rates of 0 45 1 05 and 0 81 1 49 m kyr for coquille point and cape blanco respectively late quaternary uplift rates of marine terraces yield information about deformation in the overriding plate but it is unclear if such data vary systematically with convergent margin type in order to assess the utility of the southern oregon uplift rates for predicting the behavior of the cascadia subduction zone we compared late quaternary uplift rates derived from terrace data from subduction zones around the world on the basis of this comparison the southern oregon rates of vertical deformation are not unusually high or low furthermore late quaternary uplift rates show little relationship to the type of convergent margin these observations suggest that local structures may play a large role in uplift rate variability in addition while the type of convergent margin may place an upper limit on possible uplift rate greater upper limits serve to increase the range of possible uplift rates in the case of the southern oregon coast variability in uplift rate probably reflects local structures in the overriding plate and the rate of uplift cannot be used as a simple index of the potential for great earthquakes along the southern cascadia subduction zone

rapid late pleistocene holocene uplift and coastal evolution of the southern arabian persian gulf the coastline along the southern arabian gulf between al jubail kingdom of saudi arabia and dubai uae appears to have risen at least 125 m in the last 18 000 years dating and topographic surveying of paleo dunes 43 53 ka paleo marine terraces 17 30 ka and paleo marine shorelines 3 3 5 5 ka document a rapid 1 mm a subsidence followed by a 6 mm a uplift that is decreasing with time the mechanism causing this movement remains elusive but may be related to the translation of the coastal area through the backbasin to forebulge hinge line movement of the arabian plate or alternatively by movement of the underlying infracambrian age hormuz salt in response to sea level changes associated with continental glaciation independent of the mechanism rapid and episodic uplift may impact the design of engineering projects such as nuclear power plants airports and artificial islands as well as the interpretation of sedimentation and archeology of the area

beachrock a tool for reconstructing relative sea level in the far field abstract today s understanding of sea level change developed through a combination of process based physical modelling and observational data observational data of sea level change derives from coral reefs in the far field of the former ice sheets where a geographically variable relative sea level signal is expected as a response of the earth to ocean loading given this variability and the limited geographical distribution of coral reefs there is a need to explore other non coral based sea level markers to further understand sea level change and for example to fingerprint melt water here we present beachrock as a coastal deposit suitable for relative sea level rsl observations in the far field beachrock is an intertidal deposit forming in the zone where carbonate saturated meteoric and marine water mix and p co 2 decreases we provide the conceptual framework for beachrock analysis and describe techniques suitable for analysing and dating the deposit the approach is standardised by outlining the sediment characteristics in terms of rsl indicative meaning and indicative range and is tested against published data a study conducted on coasts of the mediterranean sea exemplifies the utility of beachrock for rsl reconstruction it is shown that the precision of the reconstruction is derived from the combined uncertainty of age and tidal amplitude or tidal range the uncertainty can be reduced to half the tidal amplitude when a deposit can be ascribed to the upper or lower intertidal zone beachrock based data benefit from the lack of non quantifiable error terms such as post depositional compaction due to the instantaneous formation and high preservation potential of the deposit this underlines the high precision of beachrock based rsl reconstruction which is a prime requirement for testing and extending coral based records

lithological mapping of the troodos ophiolite cyprus using airborne lidar topographic data traditional field based lithological mapping can be a time consuming costly and challenging endeavour when large areas need to be investigated where terrain is remote and difficult to access and where the geology is highly variable over short distances consequently rock units are often mapped at coarse scales resulting in lithological maps that have generalised contacts which in many cases are inaccurately located remote sensing data such as aerial photographs and satellite imagery are commonly incorporated into geological mapping programmes to obtain geological information that is best revealed by overhead perspectives however spatial and spectral limitations of the imagery and dense vegetation cover can limit the utility of traditional remote sensing products the advent of airborne light detection and ranging lidar as a remote sensing tool offers the potential to provide a novel solution to these problems because accurate and high resolution topographic data can be acquired in either forested or non forested terrain allowing discrimination of individual rock types that typically have distinct topographic characteristics this study assesses the efficacy of airborne lidar as a tool for detailed lithological mapping in the upper section of the troodos ophiolite cyprus morphometric variables including slope curvature and surface roughness were derived from a 4 m digital terrain model in order to quantify the topographic characteristics of four principal lithologies found in the area an artificial neural network the kohonen self organizing map was then employed to classify the lithological units based upon these variables the algorithm presented here was used to generate a detailed lithological map which defines lithological contacts much more accurately than the best existing geological map in addition a separate map of classification uncertainty highlights potential follow up targets for ground based verification the results of this study demonstrate the significant potential of airborne lidar for lithological discrimination and rapid generation of detailed lithological maps as a contribution to conventional geological mapping programmes

changing moisture sources over the last 330 000 years in northern oman from fluid inclusion evidence in speleothems speleothems from hoti cave in northern oman provide a record of continental pluvial periods over the last 330 000 yr periods of rapid speleothem deposition occurred from 6000 to 10 500 78 000 to 82 000 120 000 to 135 000 180 000 to 200 000 and 300 000 to 330 000 yr ago with little or no growth during the intervening periods during each of these five pluvial periods d values of water extracted from speleothem fluid inclusions dfi are between 60 and 20 vsmow and 18o values of speleothem calcite 18oc are between 12 and 4 to vpdb these values are much more negative than modern rainfall for d or modern stalagmites for 18o previous work on the isotopic composition of rainfall in oman has shown that northern and southern moisture sources are isotopically distinct combined measurements of the d values of fluid inclusion water with calculated 18o values from peak interglacial speleothems indicate that groundwater was predominantly recharged by the southern indian ocean moisture source when the monsoon rainfall belt moved northward and reached northern oman during each of these periods

quaternary marine terraces as indicators of neotectonic activity of the ierapetra normal fault se crete greece abstract along the southern coast of the island of crete a series of east west oriented late pleistocene marine terraces exist demonstrating the significant coastal uplift of this area five uplifted terraces were mapped in detail and correlated with middle late pleistocene sea level stands following the global sea level fluctuations these terraces are deformed by the vertical movements of the nne ssw trending and dipping west ierapetra normal fault the elevation of the inner edges of the terraces was estimated at several sites by using aerial photographs and detailed topographic maps and diagrams supported by extensive field observations in this way detailed geomorphological maps were constructed utilizing gis technology all these allowed us to obtain rates of 0 3 mm yr for the regional component of uplift and 0 1 mm yr for the vertical slip movements of the ierapetra fault based on the obtained rates and the existence of coastal archaeological roman ruins it is concluded that ierapetra fault should have been reactivated sometime after the roman period

quaternary uplift along a passive continental margin oman indian ocean abstract crustal movement along the coastline of the arabian sea in oman is quantified along a 72 km long coastal section characterised by staircases of marine terraces an extensive topographic geomorphological and geological survey was conducted on these terraces and an age model based on cosmogenic nuclide 10be 36cl and optically stimulated luminescence dating is presented together with a new approach to extract palaeo shorelines from a high resolution digital elevation model the uplifting crustal block is fault bounded and is composed of obduction related peridotites overlain by shallow marine limestone nine distinct terrace levels are identified and the results indicate continuous uplift between marine isotope stage mis 5a and mis 19 the calculated uplift rates vary along the coastline and a northward tilting of the uplifted coastal block is interpreted as evidence for differential uplift the geomorphology of the terraces proves that the tilting must have taken place after the last interglacial tectonic forcing of the uplift by a crustal forebulge associated with the makran subduction zone is discussed it is also concluded that the uplift involves processes of serpentinisation of the peridotites in combination with karstification of the overlying limestone formations as water is essential for both processes climate change during the quaternary apparently played a significant role in the uplift process as well as hydro isostasy

bajada formation by monsoonal erosion of a subaerial forebulge sultanate of oman abstract a vast low gradient bajada is present in the interior of northern oman with an area of 40 000 km2 and longitudinal gradients less than 0 3 this late cenozoic bajada is 10 times larger and 10 times flatter than classical bajadas the tectonic and climatic setting that favored aerially extensive bajada formation is investigated in this paper a tectonic model is proposed that involves forebulge development associated with subduction of the arabian plate beneath the asian plate the model identifies the southern gulf of oman as a foredeep the oman mountains as a subaerial forebulge the vast bajada as a deposit that blankets the distal forebulge and the umm as samim sabkha as a backbulge basin deposit the model is supported by an excellent match between modern topography and a theoretical flexural profile of the omani lithosphere by the lateral distribution of pliocene pleistocene sediments by the inferred late miocene to pleistocene age span of the vast bajada and by evidence of active surface uplift of the oman mountains a second mechanism post orogenic exhumation of the pre existing oman mountains is likely to have accompanied and perhaps slightly preceded forebulge growth facilitating erosion and transport of sediment across the forebulge evidence for a palaeoclimatic model is provided by previous sedimentological studies and stable isotope data of cements in channel gravels as well as proxy data from odp leg 117 oman margin transport of coarse grained sediment across the bajada is interpreted to have occurred mainly during the late miocene to early pleistocene when a humid wet climate prevailed across arabia high water tables and accompanying cementation of bajada gravels may have aided long distance transport the evolution of surficial bajada sediments is correlated with changing climatic and hydrological conditions from seasonal perennial flows during the pliocene and before to mainly ephemeral and finally flash flood flows signifying increasing aridity during the pleistocene these data imply that the indian ocean monsoon represented by rainfall frequency and intensity had a more northerly range in arabia in the past compared to the present

surface uplift uplift of rocks and exhumation of rocks uplift of the surface of mountain belts requires forces that are comparable in magnitude to those associated with plate motion and therefore determination of rates of surface uplift could provide important information on the dynamics of mountain ranges rates of uplift of the surfaces of mountain ranges have not however been quantified sufficiently well that they provide useful constraints on those processes many reports off surface uplift in mountain ranges are based on mistaking exhumation of rocks or uplift of rocks for surface uplift and provide no information whatsoever on the rates of surface uplift

dating sediment burial with in situ produced cosmogenic nuclides theory techniques and limitations abstract dating sediment burial over million year time scales is crucial in many areas of the earth sciences and archeology but is often difficult using traditional techniques sediment burial can be dated by the radioactive decay of cosmogenic nuclides provided that the sediment was exposed to cosmic rays prior to burial dating calculations are straightforward if sediment is buried deeply and rapidly enough to prevent cosmogenic nuclide production after burial however the analysis can be complicated by postburial production if sediment is insufficiently shielded from secondary cosmic ray nucleons and muons this paper discusses how buried sediments can be dated over timescales up to 5 myr using 26 al and 10 be in quartz

coastal neotectonics in southern central andes uplift and deformation of marine terraces in northern chile 27 s abstract neotectonic observations allow a new interpretation of the recent tectonic behaviour of the outer fore arc in the caldera area northern chile 27 s two periods of deformation are distinguished based on large scale neogene to quaternary features of the westernmost part of the coastal cordillera late miocene to early pliocene deformations characterized by a weak ne sw to e w extension is followed by uppermost pliocene nw se to e w compression the middle pleistocene to recent time is characterized by vertical uplift and nw se extension these deformations provide clear indications of the occurrence of moderate to large earthquakes microseismic observations however indicate a lack of shallow crustal seismicity in coastal zone we propose that both long term brittle deformation and uplift are linked to the subduction seismic cycle

energy flux to a cyclonic eddy off cabo frio brazil abstract to evaluate the energy flux from the mean flow of south atlantic western boundary currents toward typical cabo frio eddies at brazilian southeast coast the southwestern atlantic circulation was simulated with the princeton ocean model throughout the study period the vertical profile of eddy available potential energy direction was monitored the results indicated that baroclinic instability eddies first appear in intermediate depths and then its signal propagates upward draining energy from the brazil current bc until it reaches the surface 30 days after its formation the depth of eddy formation is related to the vertical profile of the mean potential vorticity cross current gradient q s the beginning of the potential energy flux toward the perturbation and the origin of the eddy occurred at a similar depth and time the observed pattern suggests the following cycle 1 a well defined southwestward flowing bc in the beginning of the period with a baroclinically unstable profile o