morphology and environment of cold water coral carbonate mounds on the nw european margin cold water coral carbonate mounds owing their presence mainly to the framework building coral lophelia pertusa and the activity of associated organisms are common along the european margin with their spatial distribution allowing them to be divided into a number of mound provinces variation in mound attributes are explored via a series of case studies on mound provinces that have been the most intensely investigated belgica hovland pelagia logachev and norwegian mounds morphological variation between mound provinces is discussed under the premise that mound morphology is an expression of the environmental conditions under which mounds are initiated and grow cold water coral carbonate mounds can be divided into those exhibiting inherited morphologies where mound morphology reflects the morphology of the colonised features and developed morphology where the mounds assume their own gross morphology mainly reflecting dominant hydrodynamic controls finer scale surface morphological features mainly reflecting biological growth forms are also discussed

quaternary sediments and environments on the continental shelf off northern norway abstract based on lithologic palaeontologic and chronostratigraphic investigations of close to 200 gravity cores from troughs deep banks and shallow banks the following late quaternary environment can be outlined in the weichselian deposition of basal tills was followed by deposition of laminated clay in a sea ice environment later a pebbly pelite was deposited in the troughs at the same time as the banks were iceberg ploughed then 13 000 yrs b p a period with incipient winnowing occurred on the deep banks and deposition of sandy pelite took place in the troughs the holocene commenced with a marked environmental change due to intrusion of atlantic water the fauna changed from arctic to boreal high energy winnowing forming a lag deposit took place on the banks and high accumulation rates in the troughs occurred due to the winnowing and sediment influx from the downwasting continental icesheet during the later part of the holocene the winnowing diminished on the deeper banks on the shallow banks and on the shelf break it still prevails and in the troughs calcareous sandy mud is being deposited the surface sediments comprise three main facies bouldery and pebbly sand sand and sandy mud whose distribution mainly depends on the prevailing bottom current regime the composition of the older quaternary sediments is demonstrated by some selected seismic profiles

active thrusting and folding along the northern tien shan and late cenozoic rotation of the tarim relative to dzungaria and kazakhstan we have studied geometries and rates of late cenozoic thrust faulting and folding along the northern piedmont of the tien shan mountain belt west of urumqi where the m 8 3 manas earthquake occurred on december 23 1906 the northern range of the tien shan rising above 5000 m overthrusts a flexural foredeep filled with up to 11 000 m of sediment of the dzungarian basement our fieldwork reveals that the active thrust reaches the surface 30 km north of the range front within a 200 km long zone of neogene quaternary anticlines fault scarps are clearest across inset terraces within narrow valleys incised through the anticlines by large rivers flowing down from the range in all the valleys the scarps offset vertically the highest terrace surface by the same amount 10 2 0 7 m inferring an early holocene age 10 2 kyr for this terrace which is continuous with the largest recent fans of the piedmont yields a rate of vertical throw of 1 0 0 3mm yr on the main active thrust at the surface a quantitative morphological analysis of the degradation of terrace edges that are offset by the thrust corroborates such a rate and yields a mass diffusivity of 5 5 2 5 m 2 kyr a rather fresh surface scarp 0 8 0 15 m high that is unlikely to result from shallow earthquakes with 6 m 7 in the last 230 years is visible at the extremities of the main fold zone we associate this scarp with the 1906 manas earthquake and infer that a structure comprising a deep basement ramp under the range gently dipping flats in the foreland and shallow ramps responsible for the formation of the active fault propagation anticlines could have been activated by that earthquake if so the return period of a 1906 type event would be 850 380 years the small size of the scarp for an earthquake of this magnitude suggests that a large fraction of the slip at depth 2 3 is taken up by incremental folding near the surface comparable earthquakes might activate flat detachments and ramp anticlines at a distance from the front of other rising quaternary ranges such as the san gabriel mountains in california or the mont blanc aar massifs in the alps we estimate the finite cenozoic shortening of the folded dzungarian sediments to be of the order of 30 km and the cenozoic shortening rate to have been 3 1 5 mm yr assuming comparable shortening along the tarim piedmont and minor additional active thrusting within the mountain belt we infer the rate of shortening across the tien shan to be at least 6 3 mm yr at the longitude of manas 85 5 e a total shortening of 125 30 km is estimated from crustal thickening assuming local airy isostatic equilibrium under the same assumption serial n s sections imply that cenozoic shortening across the belt increases westwards to 203 50 km at the longitude of kashgar 76 e as reflected by the westward increase of the width of the belt this strain gradient implies a clockwise rotation of tarim relative to dzungaria and kazakhstan of 7 2 5 around a pole located near the eastern extremity of the tien shan west of hami 96 e 43 5 n comparable to that revealed by paleomagnetism between tarim and dzungaria 8 6 8 7 a 6 mm yr rate of shortening at the longitude of manas would imply a rate of rotation of 0 45 m y and would be consistent with a shortening rate of 12 mm yr north of kashgar taking such values to be representative of late cenozoic rates would place the onset of reactivation of the tien shan by the india asia collision in the early to middle miocene 16 22 9 m y in accord with the existence of particularly thick late neogene and quaternary deposits such reactivation would thus have started much later than the collision roughly at the time of the great mid miocene changes in tectonic regimes denudation and sedimentation rates observed in southeast asia the himalayas and the bay of bengal and of the correlative rapid change in seawater sr isotopic ratio 20 to 15 ma like these other changes the rise of the tien shan might be a distant consequence of the end of indochina s escape

freakish sea state and swell windsea coupling numerical study of the suwa maru incident 1 on 23 june 2008 a fishing boat with 20 crewmembers onboard sank in reportedly moderate sea state conditions in the kuroshio extension region east of japan to determine the sea state at the time of the incident we conducted a hindcast wave simulation as realistically as possible using an improved third generation wave model driven by wind and current reanalysis products our results indicated that at the time of the accident the wave steepness increased and the spectral peakedness narrowed creating a sea state favorable for freak wave occurrence due to quasi resonance detailed analyses of the spectral evolution revealed that nonlinear coupling of swell and windsea waves was the key to generating the narrow spectrum under the influence of rising wind speed the swell system grew exponentially at the expense of the windsea energy and the bimodal crossing sea state transformed into a freakish unimodal sea

dating sediments using potassium feldspar single grain irsl initial methodological considerations abstract potassium feldspar shows good potential for luminescence dating of quaternary sediments in several locations assessed including california tibet mongolia spain egypt the uk and new zealand in many of these locations feldspar has particular importance owing to the low sensitivity of quartz osl optically stimulated luminescence signals observed potassium feldspar rich mineral fractions of sand sized grains from a range of fluvial alluvial lake shoreline and glacial contexts were separated and equivalent dose and fading determinations performed for single grains besides conventional multiple grain aliquots in some cases using a protocol modified from a post infra red irsl infra red stimulated luminescence procedure most samples but not all contain a significant proportion of grains that provide irsl signals sufficiently sensitive to determine equivalent dose values two main types of response have been observed one group of samples displays regular behavior with the majority of grains providing either a uniform equivalent dose de value for well bleached samples or a uniform minimum dose value with many higher values presumably caused by incomplete zeroing uniform de values or minimum values suggest that the magnitude of signal reduction by anomalous fading for grains of different sensitivity is the same for all grains a second common pattern of behavior is observed for these samples the minimum equivalent dose value is greater for grains with higher sensitivities a surprising feature of this behavior for a subset of samples is an apparent saturating stretched exponential relationship between minimum equivalent dose and irsl sensitivity samples in both groups contain rare grains with significantly lower de values interpreted as intrusive grains probably introduced by bioturbation this paper provides an initial survey of results and briefly explores single grain fading determination besides comparisons of age estimates between different methods an improved separation method to isolate the most sensitive grains referred to as super k is introduced resulting in significant enhancement of the number of grains with bright irsl signals

the fugloy reef at 70 n acoustic signature geologic geomorphologic and oceanographic setting this is the first in depth study of a cluster of cold water coral reefs the fugloy reefs found at 70 n on the norwegian margin combining high resolution seismic reflection data side scan sonar video images and oceanographic measurements reveals the geologic geomorphologic and oceanographic setting in which the reefs occur the reefs consist mainly of the scleractinian ahermatypic lophelia pertusa and exist below the thermocline at water depths between 140 m and 190 m the reefs appear as cone shaped acoustically transparent features on seismic reflection data consistently located in places characterized by the availability of hard substrate high relief and periodical exposure to high tidal currents 30 cm s these currents transport water of the norwegian atlantic current to the reefs from an area with fluid expulsion related pockmarks the spatial relationship between reef pockmark locations and current directions suggests that seepage of biogenic gas might be a catalyst to reef growth with a height of more than 40 m some of the fugloy reefs are among the highest reported from the norwegian margin this indicates highly favourable growth conditions and conservative estimates indicate a net growth rate for the reefs of 5 mm year we expect that cold water reefs will be found further north along the barents sea margin as general awareness on the geophysical signature and appearance of the reefs increases because all known factors involved in reef establishment and growth are within the required intervals also further north

bed by bed fold growth by kink band migration sant llorenc de morunys eastern pyrenees ahstract rowth strata deposited over and against the flank of the sant llorenc de morunys fold during its final stages of deformation have been mapped at high resolution as the basis for unraveling the kinematics of fold growth we use restoration techniques based on normal balancing assumptions to decipher the detailed kinematic history of folding the progressive restorations as well as balanced forward modeling show that the last few hundred meters of fold growth were dominated by kink band migration of a sort that is typical of much faultrelated folding the kink band migration has produced complex anticlinal hinge zone geometry including segmented fold hinges linked by disconformities and unconformities which has direct and detailed explanation in terms of fluctuations in deposition rate relative to curved hinge kink band migration rate large fluctuations in the convolution of non steady sedimentation and deformation are demonstrated although the absolute fluctuations in deformation and sedimentation are unknown at a length scale of 100 m kink band migration with little or no deposition is interspersed with sedimentation with little or no deformation at the length scale of 500 m deposition ranges from 200 to 50 of uplift 0 1997 elsevier science ltd all rights reserved

the neogene xiyu formation a diachronous prograding gravel wedge at front of the tianshan climatic and tectonic implications the tarim and junggar basins in central asia are capped by a thick pile of conglomerates called the xiyu formation that are commonly linked to a change in climate and or accelerated uplift near the plio pleistocene boundary in order to better understand their origin and significance we carried out a combined structural and magnetostratigraphic study in the quilitage syncline southern tianshan where the base of the xiyu conglomerates is observed at both sides of the syncline a balanced cross section shows that even at a local scale the base of the xiyu conglomerates cannot be regarded as a single continuous stratigraphic layer on the southern flank of the quilitage syncline we collected 172 samples collected for magnetostratigraphic dating identify 17 polarity chrons that date the new section from 5 2 to 1 7 ma and constrain the base of the xiyu conglomerate here at 1 7 ma this is 4 2 ma younger than the age of the xiyu previously found on the northern limb of the same syncline together with other magnetostratigraphic studies carried out around the tianshan our study unambiguously demonstrates that the onset of deposition of the xiyu conglomerates is diachronous and that the conglomerates are systematically younger toward the basin consequently the xiyu formation should not be considered as a chronostratigraphic marker related to any particular tectonic or climatic event but is instead a prograding gravel wedge that has prograded over the underthrusting forelands a synthesis of chronologic and structural results yields progradation rates over the last 10 ma on the order of 2 0 mm yr and 3 9 mm yr south and north of the tianshan mountains respectively these rates are comparable to the shortening rate across the tianshan range suggesting that underthrusting is the main factor governing the progradation rate of the xiyu formation

growth of north east atlantic cold water coral reefs and mounds during the holocene a high resolution u series and 14c chronology we investigated the holocene growth history of the mingulay reef complex a seascape of inshore cold water coral reefs off western scotland using u series and radiocarbon dating methods both chronologies revealed episodic occurrences of the reef framework forming scleractinian coral lophelia pertusa during the late holocene downcore u series dating revealed unprecedented reef growth rates of up to 12 mm a 1 with a mean rate of 3 4 mm a 1 our study highlighted a persistent hiatus in coral occurrence from 1 4 ka to modern times despite present day conditions being conducive for coral growth the growth history of the complex was punctuated at least twice by periods of reduced growth rates 1 75 2 8 ka 3 2 3 6 ka and to a lesser extent at 3 8 4 ka and at 4 2 ka timing of coral hiatuses and reduced reef growth rates at mingulay were synchronous with those occurring across the wider northern european region which suggests a close relationship between these ecosystems and large scale shifts in palaeoenvironmental regimes associated with changes to the north atlantic subpolar gyre

cold water coral mounds on the pen duick escarpment gulf of cadiz the microsystems project approach here we present a case study of three cold water coral mounds in a juvenile growth stage on top of the pen duick escarpment in the gulf of cadiz alpha beta and gamma mounds although cold water corals are a common feature on the adjacent cliffs mud volcanoes and open slope no actual living cold water coral has been observed this multidisciplinary and integrated study comprises geophysical sedimentological and bio geochemical data and aims to present a holistic view on the interaction of both environmental and geological drivers in cold water coral mound development in the gulf of cadiz coring data evidences past or present methane seepage near the pen duick escarpment several sources and pathways are proposed among which a stratigraphic migration through uplifted miocene series underneath the escarpment the dominant morphology of the escarpment has influenced the local hydrodynamics within the course of the pliocene as documented by the emplacement of a sediment drift predominantly during post middle pleistocene glacial episodes favourable conditions were present for mound growth an additional advantage for mound formation near the top of pen duick escarpment is presented by seepage related carbonate crusts which might have offered a suitable substrate for coral settling the spatially and temporally variable character and burial stage of the observed open reef frameworks formed by cold water coral rubble provides a possible model for the transition from cold water coral reef patches towards juvenile mound these rubble graveyards not only act as sediment trap but also as micro habitat for a wide range of organisms the presence of a fluctuating sulphate methane transition zone has an important effect on early diagenetic processes affecting both geochemical and physical characteristics transforming the buried reef into a solid mound nevertheless the responsible seepage fluxes seem to be locally variable as such the origin and evolution of the cold water coral mounds on top of the pen duick escarpment is probably more than any other ne atlantic cold water coral mound province located on the crossroads of environmental hydrodynamic and geological seepage pathways

active thrust sheet deformation over multiple rupture cycles a quantitative basis for relating terrace folds to fault slip rates many recent thrust fault earthquakes have involved coseismic surface faulting and folding revealing the multifaceted nature of active thrust sheet deformation we integrate records of surface deformation subsurface structure and geochronology to investigate active surface deformation over multiple rupture cycles across the southern junggar thrust sjt in the southern junggar basin nw china fluvial terrace geometries extracted from a 1 m digital elevation model reveal records of surface faulting across a prominent fault scarp in addition terraces exhibit progressive folding across fold scarps fault and fold scarps are spatially coincident with a surface emergent sjt splay and subsurface fault bends along the sjt respectively constrained by seismic reflection data we quantify the magnitude of fault slip at depth implied by fold scarps along holocene aged terraces our method yields results consistent with independent estimates of slip implied by fault scarp relief for the same terraces four late quaternary terrace records are less continuous preserved only as fold scarps that suggest folding kinematics involving a component of limb rotation we develop a new method for quantifying fault slip at depth from terrace folds using a mechanical forward modeling approach our analysis yields quantitative relations between fold dip and fault slip allowing us to quantify sjt fault slip from terrace folds from 250 ka present sjt fault slip rate has decelerated from 7 0 mm yr in the late quaternary to 1 3 mm yr throughout the holocene these results provide new insight into the kinematics of fault bend folding for natural structures and define new methods to accurately estimate fault slip and slip rates from terrace folds in active thrust sheets

environmental boundary conditions of cold water coral mound growth over the last 3 million years in the porcupine seabight northeast atlantic iodp expedition 307 made it for the first time possible to investigate the entire body of a cold water coral carbonate mound here we provide new insights into the long term history of challenger mound on the european continental margin off ireland this study is based on age determinations 230th u 87sr 86sr and geochemical signals mg li and ba ca measured in the scleractinian cold water coral lophelia pertusa from iodp site 1317 in the porcupine seabight the paleoceanographic reconstructions reveal that coral growth in the porcupine seabight was restricted to specific oceanographic conditions such as enhanced export of primary production and bottom water temperatures bwt between 8 10 c related to the water mass stratification of the mediterranean outflow water mow and eastern north atlantic water enaw the geochemical signals from the coral skeletons can be explained by the close interaction between cold water coral growth sea surface productivity and the surrounding water masses the boundary layer between mow and enaw enhanced sea surface productivity and the build up of a stable water mass stratification between enaw and mow caused enhanced nutrient supply at intermediate water depths and facilitated a steady mound growth between 3 0 2 1 ma with the decrease in sea surface productivity and related reduced export productivity the food supply was insufficient for rapid coral mound growth between 1 7 1 ma during the late pleistocene over the last 0 5 myr mound growth was restricted to interglacial periods during glacials the water mass boundary between enaw mow probably was below the mound summit and hence food supply was not sufficient for corals to grow

gas hydrate crystals may help build reefs during a recent cruise in the porcupine basin off southwest ireland we discovered two extensive and hitherto largely unsuspected deep water reef provinces including a giant cluster of hundreds of buried mounds the ring shapes of many reefs suggest that they are caused by an axial fluid expulsion at the sea bed a transient flow well confined in space and time we are exploring various hypotheses but a stimulating avenue for research is opened by a glacially controlled growth pulse and subsequent decay of a shallow layer of gas hydrates as a methane buffer and probably indirectly as a ground for overlying biological communities

late cenozoic tectonic deformation across the northern foreland of the chinese tian shan abstract to understand the reactivation and intensified uplift of the tian shan range in the cenozoic the age of development of the associated series of anticlinal belts formed in the southern and northern foreland basins must be constrained to estimate the shortening magnitude and rates in the northern foreland basin we provide here regional structural analysis based on identified growth strata dated with existing magnetostratigraphy together with balanced cross sections from interpreted seismic data these results indicate that three paralleled rows of anticlinal belts have developed sequentially from south to north accommodating a total shortening of 15 km at the location of the structurally restored seismic section provided here these three belts present different structural deformational styles with the southern qingshuihe anticline as a basement involved fold the middle huoerguosi anticline as a fault bend fold and the northern anjihai anticline as a fault propagation fold growth strata inferred from seismic profiles start stratigraphically far below growth strata observed on the outcrop the latter coincide with accelerated folding of the anticlinal belts at 6 ma for the southern 2 ma for the middle 1 ma for the northern our results imply that the northern tian shan foreland rates of deformation were lower until late miocene and increased in more recent times to values in line with gps derived rates

high resolution temperature observations of a trapped nonlinear diurnal tide influencing cold water corals on the logachev mounds abstract a high resolution thermistor string mooring of 120 m length was used to measure turbulence processes in the water layer above the foot of a densely populated cold water coral mound at 919 m depth at the southeast slope of rockall bank in the logachev area north east atlantic ocean as expected from previous current observations the temperature data reveal a dominant diurnal tidal periodicity associated with topography trapped weakly bottom intensified waves these baroclinic diurnal waves are driven to near resonance around the mound and have vertical amplitudes exceeding the mooring line their horizontal excursion length matches the size of the mound which causes a residual current around and flux up the mound as their particle velocities also match the phase speed of the wave traveling around the mound these waves can become highly nonlinear and show largest turbulence due to wave breaking at the transition from warming downslope to cooling upslope tidal phase averaged over the entire 9 day time series and the 120 m vertical range mean turbulent kinetic energy dissipation amounts to 2 2 1 1 10 7 w kg 1 and mean vertical eddy diffusivity to 9 5 10 3 m2 s 1 with short term variations over four orders of magnitude such large turbulence more than 100 times larger than open ocean values and comparable with that observed in tidally energetic shelf break shallow sea areas will affect the nutrient replenishment of the cold water corals

late pleistocene acceleration of deformation across the northern tianshan piedmont china evidenced from the morpho tectonic evolution of the dushanzi anticline we document the temporal evolution of deformation in the northern tianshan piedmont where the deformation is partitioned across several thrusts and folds we focus on the dushanzi anticline where abandoned terraces and growth strata allow us to constrain the history of folding since the miocene based on subsurface seismic imaging structural measurements and morphological analysis we show that this anticline is associated with two decollement levels we use kink band migration in growth strata dated by paleomagnetism to constrain the shortening from the mio pliocene to the holocene our results show that the dushanzi anticline has been active since at least 8 ma and that the fold grew at a steady shortening rate of 0 6 0 1 mm yr from 8 to 1 5 ma with possible variations from 2 5 to 1 5 ma then it accelerated rapidly to a rate of 4 3 1 0 mm yr over at least the last 100 ka these results together with similar temporal shortening evolutions across other structures suggest that the deformation rate across the eastern tianshan piedmont increased relatively recently this may reflect either a redistribution of the deformation from the internal structures toward the borders or a general acceleration of the deformation across the entire range

india eurasia collision chronology has implications for crustal shortening and driving mechanism of plates the motion of the indian plate is determined in an absolute frame of reference and compared with the position of the southern margin of eurasia deduced from palaeomagnetic data in tibet the 2 600 900 km of continental crust shortening observed is shown to have occurred in three different episodes subduction of continental crust intracontinental thrusting and internal deformation and lateral extrusion the detailed chronology of the collision and plate reorganizations in the indian and pacific oceans supports the hypothesis that slab pull is a dominant driving mechanism of plate tectonics

new space geodetic constraints on the distribution of deformation in central asia abstract results from repeated measurements across a 90 sites global positioning system network in central asia provide direct evidence of current high rates of tectonic deformation far north of the india eurasia suture zone the data help to quantify both the partitioning of deformation within the seismically active tien shan and northern pamirs as well as the ongoing rotation of virtually undeformed blocks such as the tarim with respect to stable eurasia the nnw to sse shortening rates derived from the computations reach values of 23 3 mm yr 1 over the ranges studied suggesting that regional deformation rates have increased considerably within the study area since the onset of cenozoic shortening 20 25 myr ago

quaternary climate change and the formation of river terraces across growing anticlines on the north flank of the tien shan china nested stream terraces warped upward over actively growing anticlines along the north flank of the tien shan in western china appear to record alternating phases of valley widening and incision differences of relative heights between remnants of four separate strath terraces along one river and between two such terraces along another reach 100 to 120 m over the crests of the anticlines we infer that this spacing is due to alternating stages of valley widening and rapid incision associated with climate changes with a periodicity of 100 kyr the crests of the anticlines appear to emerge from the aggrading flanks of the anticlines at an average rate of about 1 mm a the maximum heights of 25 and 35 10 m for the lowest terraces above their projected initial profiles imply ages of roughly 25 kyr and 35 kyr 10 kyr hence they suggest that flood plains which were abandoned to form the terraces developed adjacent to active stream beds during the last glacial period when climates were relatively

present day crustal deformation in china constrained by global positioning system measurements global positioning system gps measurements in china indicate that crustal shortening accommodates most of india s penetration into eurasia deformation within the tibetan plateau and its margins the himalaya the altyn tagh and the qilian shan absorbs more than 90 of the relative motion between the indian and eurasian plates internal shortening of the tibetan plateau itself accounts for more than one third of the total convergence however the tibetan plateau south of the kunlun and ganzi mani faults is moving eastward relative to both india and eurasia this movement is accommodated through rotation of material around the eastern syntaxis the north china and south china blocks east of the tibetan plateau move coherently east southeastward at rates of 2 to 8 millimeters per year and 6 to 11 millimeters per year respectively with respect to the stable eurasia

alluvial sequence in the north piedmont of the chinese tian shan over the past 550 kyr and its relationship to climate change abstract a new division of middle and late pleistocene alluvial sequence in the north piedmont of the chinese tian shan based on geomorphologic stratigraphic and chronologic criteria provides a framework for examining their relationship to climate change during glacial interglacial transitions over the past 550 kyr at least four major alluviation episodes occurred within the piedmont along the major river valleys in this region each episode of alluvial fan deposition morphologically correlates with a major river terrace these correlations create a regionally applicable framework for subdivision of the quaternary alluvial sequence in the study area where seven stepped river terraces are defined our new chronology of this fluvial sequence suggests that following intervals of aggradation three highest river terraces and equivalent alluvial fans were abandoned at 530 ka 300 ka and 10 ka respectively paleosols at the base of the loess sequences that directly overlie the older terraces and fans suggest that episodes of aggradation occurred late in the glacial cycles the subsequent incision that caused abandonment stabilization of these terraces and fans occurred near to glacial interglacial transitions a relatively high degree of synchrony in major river incision events across the piedmont despite disruption by several discrete structure zones with asychronous tectonic activities supports the dominant control exerted by climatic conditions on alluvial deposition and terrace creation during the quaternary across the north piedmont of the chinese tian shan

a theory of the ka band radar imaging mechanism of a submerged wreck and associated bed forms in the southern north sea the ka band radar imaging mechanism of the submerged wreck sand ribbon of the motor vessel m v birkenfels in the southern north sea is investigated by applying the quasi specular scattering theory and considering the capillary as well as the gravity wave ranges of the wave energy density spectrum for the imaging of wrecks and other oceanographic and meteorological phenomena at the sea surface it is assumed that quasi specular scattering becomes dominant at higher radar frequencies like ka and x band and wind speeds 7 8 m s 1 multibeam echo sounder images of the birkenfels wreck and associated sand ribbons as well as other available environmental in situ data have been analyzed the formation of sand ribbons at the sea bed and the manifestation of its radar signatures at the water surface are caused by an elliptical vortex or helical flow cell triggered by unidirectional tidal current flow interacting with the wreck the difference between simulated and measured normalized radar cross section nrcs modulation as a function of the space variable is less than 31 6 results are presented for nrcs simulations dependent on position for different effective incidence angles unidirectional current speeds wind speeds and relaxation rates the calculated current gradient or strain rate of the imaging theory has the same order of magnitude as those obtained for marine sand waves this implies that the responsible hydrodynamic interaction mechanism is able to produce radar signatures of submerged wrecks sand ribbons and make them visible at the sea surface

unbalanced sediment budgets in the catchment alluvial fan system of the kuitun river northern tian shan china implications for mass balance estimates denudation and sedimentation rates in orogenic systems mass balances are often used to calculate sediment fluxes in foreland basins and denudation rates in adjacent mountain ranges on intermediate to long timescales from a few tens of thousand to a million years here we study the simple quaternary catchment alluvial fan system of the kuitun river in northern tian shan to discuss some ideas about sediment storage release and bypass in relatively short 100 km long sediment routing systems this study shows that the kuitun catchment and piedmont areas clearly present evidence of a significant and temporary storage of sediments during the pleistocene these sediments were then excavated and delivered farther into the foreland basin during the holocene the difference between the volumes of materials released from the catchment and piedmont areas 5 5 1 7 km3 and the volume stored in a contemporaneous fan downstream 2 6 0 6 km3 indicates that the latter did not trap the whole sediment load transported by the river the alluvial fan was bypassed by 27 to 78 of this load toward its distal alluvial plain if this value is well estimated it implies a major volumetric partitioning of the deposits between the fan and the alluvial plain with a very high sedimentation rate in the fan 1 97 0 52 mm y 1 and a much lower one downstream 0 11 0 11 mm y 1 however this volumetric partitioning might only occur during periods with a very specific hydrological regime such as the holocene deglaciation eventually the peculiar sediment storage and release pattern within the kuitun catchment and piedmont areas during the pleistocene and holocene complicates the calculation of mean paleodenudation rates using either sediment budgets or in situ produced cosmogenic nuclides

holocene hydrological changes inferred from alluvial stream entrenchment in north tian shan northwestern china abstract we analyze the possible contribution of climate change or tectonics on fluvial incision from the study of a case example along the northern flank of tian shan the rivers that exit the high range fed large alluvial fans by the end of the last glacial period they have since deeply entrenched the piedmont by as much as 300 m we have surveyed several terraces that were cut and abandoned during river entrenchment providing information on intermediate positions of the riverbed during downcutting they suggest a gradual decline in river slope during a major phase of incision throughout the holocene tectonic uplift affects only a zone about 5 km wide corresponding to a growing anticline and is shown to account for about 10 of total incision incision was therefore most probably driven by climate change from observed fluvial incision we estimate the water discharge in excess of that needed to carry the sediments supplied by hillslope erosion in the headwaters we used a model based on a transpor

denudation intensity and control in the chinese tian shan new constraints from mass balance on catchment alluvial fan systems tectonics and climate are usually seen as the main controlling factors of denudation rates which seem to rise with the tectonic activity and to decrease when the climate becomes drier however the low denudation rates observed in semi arid to arid contexts are generally measured on orogenic plateaus where the respective influence of the flat relief and the dry climate cannot really be unravelled the chinese tian shan was chosen as a case study in the northern piedmont of this mountain range a series of well preserved quaternary alluvial fans offer the opportunity to perform a mass balance study at the scale of several catchment areas and several hundreds of thousands of years based on a geometrical reconstruction of these fans the volumes of sediments exported out of 10 drainage basins during the middle late pleistocene from 300 to 12 kyr and the holocene from 12 kyr to present have been estimated from these volumes an average denudation rate of 135 m myr was determined in the tian shan range for the last 300 kyr in agreement with other mass balances performed in the same area the typical denudation intensity of the northern tian shan is thus of a few hundred meters per million years at most regardless of the space and time scales considered from a comparison with denudation rates in other mountain ranges throughout the world we suggest that a dry climate can dramatically limit the denudation intensity even in active orogenic systems with a high topographic gradient like the tian shan as a result the time required to reach equilibrium between denudation and rock uplift in these systems could be extremely long i e of more than several million years copyright 2016 john wiley sons ltd

crossing sea state and rogue wave probability during the prestige accident we discuss the crossing sea state and the probability of rogue waves during the accident of the tanker prestige on 13 november 2002 we present newly computed hindcast spectra for every hour during that day at nearby locations showing the development of a bimodal sea state with two wave systems crossing at nearly right angle we employ four different nonlinear models capable of computing the phase resolved sea surface from the hindcast spectra allowing us to estimate statistics for the occurrence of rogue waves at the location and moment of the accident the models give expected values for the kurtosis 3 0119 0 0078 the models coincide that the maximum crest elevation was about 5 6 larger than the expected maximum crest elevation in a gaussian sea at the moment of the accident we also conclude that the possible nonlinear interaction between the two crossing wave systems practically did not modify neither the kurtosis nor the largest crest elevation

carbonate budget of a cold water coral mound challenger mound iodp exp 307 abstract cold water coral ecosystems represent a worldwide distributed carbonate factory which is so far not considered in global carbonate budget estimations the herein presented study evaluates the carbonate budget of a complete cold water coral mound sequence from challenger mound belgica mound province porcupine seabight sw offshore ireland drilled during iodp expedition 307 reaching back to the late pliocene versus background sediment derived calcite dominated carbonate cores from adjacent drift deposits were examined for comparison studies challenger mound which developed in a fast growth phase unit m1 2 7 to 1 6 ma and a slower growth phase or mound decline unit m2 0 8 ma until today separated by a so called mound crisis displays increased carbonate accumulation rates for both phases 17 3 g cm 2 ka for unit m1 and 5 7 g cm 2 ka for unit m2 compared to adjacent drift deposits but only about 33 to 40 wt of the carbonate is derived from corals bulk sedimentation rates of on and off mound deposits suggest a decline of challenger mound since the onset of drift deposition in the area about 1 2 ma ago yet total carbonate accumulation rates as well as hemipelagic background sediment derived carbonate accumulation rates from challenger mound unit m2 still exceed the carbonate accumulation rates of the adjacent drift deposits the selective enrichment of background sediment derived carbonate by a factor of 2 0 in a cwc mound is herein observed for the first time this might be caused by the different hydrodynamic behaviour and slower settlement of marine fluff rich in calcareous detritus compared to siliciclastic sediments and its effective baffling by the coral framework and or the active catch of the calcareous plankton by the corals the carbonate accumulation rates of challenger mound are about 4 to 12 of the carbonate accumulation rates of tropical shallow water reefs but exceeds the carbonate accumulation rates of continental slopes by a factor of 3 9 to 11 8 the carbonate production for the entire belgica mound province is estimated with 3 2 10 3 t a for unit m1 and 1 0 10 3 t a for unit m2

limited impact of quaternary glaciations on denudation rates in central asia because of its essential role in coupling climate and tectonics denudation is a key parameter when constraining the history of earth s surface this is particularly true at the pliocene pleistocene transition and the potential impact of the onset of quaternary glaciations remains strongly debated in the present study we measured in situ cosmogenic 10be within continuous late cenozoic sedimentary sections that had already been dated using magnetostratigraphy the new data were obtained from four sedimentary basins in the northern and southern tianshan range central asia we first thoroughly discuss how in situ cosmogenic 10be concentrations can be corrected for radioactive decay and for the contribution of postdepositional cosmogenic accumulation to derive the paleo denudation rates our analysis shows that in the four sedimentary records the potential bias remains low enough to consider the derived denudation rates reliable the four records although likely influenced by local particularities due to lithological heterogeneity and local tectonics display similar trends of continuously increasing denudation between ca 9 ma and the present these rates have remained relatively high but steady since 4 ma 1 5 m y before the onset of the quaternary glacial cycles though the rejuvenation of the tianshan range since 11 ma may explain most of the progressive increase 5 in denudation our data suggest that the quaternary glaciations had only a limited impact on denudation in the tianshan our data however indicate an increase in the spatial and high frequency variability 1 m y of the denudation rates between 3 and 1 ma this may correspond to a transient readjustment of the landscape in response to the onset of quaternary glacial cycles

aggradation and carbonate accumulation of holocene norwegian cold water coral reefs cold water coral ecosystems present common carbonate factories along the atlantic continental margins where they can form large reef structures there is increasing knowledge on their ecology molecular genetics environmental controls and threats available however information on their carbo nate production and accumulation is still very limited even though this information is essential for their evaluation as carbonate sinks the aim of this study is to provide high resolution reef aggradation and carbonate accumulation rates for norwegian cold water coral reefs from various settings sunds inner shelf and shelf margin furthermore it introduces a new approach for the evaluation of the cold water coral preservation within cold water coral deposits by computed tomography analysis this approach allows the differentiation of various kinds of cold water coral deposits by their macrofossil clast size and orientation signature the obtained results suggest that preservation of cold water coral frameworks in living position is favoured by high reef aggradation rates while preservation of coral rubble prevails by moderate aggradation rates a high degree of macrofossil fragmentation indicates condensed intervals or unconformities the observed aggradation rates with up to 1500 cm kyr 1 exhibit the highest rates from cold water coral reefs so far reef aggradation within the studied cores was restricted to the early and late holocene available datings of norwegian cold water corals support this age pattern for other fjords while on the shelf cold water coral ages are reported additionally from the early middle holocene the obtained mean carbonate accumulation rates of up to 103 g cm 2 kyr 1 exceed previous estimates of cold water coral reefs by a factor of two to three and by almost one order of magnitude to adjacent sedimentary environments shelf slope and deep sea only fjord basins locally exhibit carbonate accumulation rates in the range of the cold water coral reefs furthermore cold water coral reef carbonate accumulation rates are in the range of tropical reef carbonate accumulation rates these results clearly suggest the importance of cold water coral reefs as local maybe regional to global carbonate sinks

single grain post ir irsl signals of k feldspars from alluvial fan deposits in baja california sur mexico single grains of k feldspar from alluvial fan units are dated using a more time stable signal the post infrared infrared stimulated luminescence or post ir irsl a quick measurement protocol is discussed fast post ir irsl that stimulates first with the ir diodes at the lower temperature and then measures grain by grain at the higher temperature a criterion is offered for rejecting outlying grains based on hierarchical clustering single grain fading rates are found to diverge from single aliquot fading values and the fading rates from the brightest subset of grains correspond well with an infinite age cobble and independent age control age comparison with a cosmogenic depth profile age shows agreement at 1 the depositional chronology suggests that the climate responsible for regionally extensive upper regime floods which aggraded the older units transitioned into a climate producing weaker channelized floods around the late pleistocene holocene transition

late weichselian deglaciation and early holocene development of a cold water coral reef along the lopphavet shelf northern norway recorded by benthic foraminifera and ostracoda cold water coral cwc settlement in northern norway is strongly related to the outlet glaciers of the fennoscandian ice sheet and dating of known cwc structures show clearly post glacial ages two gravity cores pos391 559 2 277 cm long and pos391 559 3 282 cm long were recovered on a cwc reef in the area of lopphavet northern norway detailed investigations on lithology sediment structures and composition micropaleontology foraminifera and ostracoda and ams 14c dating on the epibenthic foraminifera discanomalina coronata were performed on the two cores phosphorus analyses were performed only on core pos391 559 3 results indicate that the whole core pos391 559 2 is representative of a cwc reef environment the base of the core is dated at 10 600 120 cal yr bp thus representing one of the oldest ages of a norwegian coral reef core pos391 559 3 documents the passage from a proximal glacier environment characterized by fine silty sediments with intercalation of several dropstone layers to a cwc ecosystem the transition from the glacial to the interglacial stage is dated as old as 10 725 205 cal yr bp whereas the base of the core is dated to an age of 15 300 550 cal yr bp diversity of benthic foraminifera is higher within the cwc especially in the intervals containing coral framework five clusters are identified based on the bray curtis similarity term analyses and the interpretation of data shows that they are related to different ecological settings e g fluctuations of the sea ice cover influence of the warmer and more saline atlantic water masses transitional to a fully interglacial environment well oxygenated nutrient rich and high current setting being conducive to cwc ostracod assemblages show that these crustaceans may be also used to characterize sedimentary facies on cwc reefs

do carbonate reefs form due to fluid seepage buried carbonate reefs are favoured hydrocarbon prospecting targets mainly due to their high porosity and potential for containing large quantities of petroleum the question of the true relationship between reef structure and the internally trapped fluids hydrocarbons is here raised as one of cause and effect in other words which came first the hydrocarbons or the carbonate reef itself modern bioherms and seabed carbonate reefs in amongst other locations the north sea and the gulf of mexico are shown to form in close association with active hydrocarbon seepages mainly based on results from ecological studies at deep ocean vent communities a new model for carbonate reef formation is promoted that such reefs form at locations containing high concentrations of bacteria and other microorganisms suspended in the water column as a result of seeping fluids solutions and gases that provide some of the energy basis and carbon source for ecosystems independently of photosynthesis therefore on burial and effective sealing capping these carbonate reefs become hydrocarbon reservoirs trapping and accumulating the very minerals on which they in the first place were dependent

syntectonic sedimentation effects on the growth of fold and thrust belts we use two dimensional mechanical models to investigate the effects of syntectonic sedimentation on fold and thrust belt development testing variable syntectonic wedge top and foredeep sediment thicknesses and flexural rigidities model results indicate a first order control of syntectonic sedimentation on thrust sheet length and thrust spacing thrust sheets are longer when syntectonic sediment thickness and or flexural rigidity increase comparison with observations from several fold and thrust belts confirms this first order control of syntectonic sedimentation

closing history of the southern tianshan oceanic basin western china an oblique collisional orogeny abstract the tianshan tien shan range is an important paleozoic collisional orogenic belt and the key to understand the central asia tectonic evolution this paper integrates our research results with the existing chinese and international literature on sedimentology geochemistry isotopic geochronology paleontonology and paleomagnetism of the tianshan and tarim regions to propose that the oblique collision may have played an important role in the late paleozoic closing of the southern tianshan oceanic basin as a result of the sinian latest proterozoic younger than 800 ma continental extension and rifting process the tarim and yili blocks separated from their parent continent in the late cambrian ordovician the southern tianshan oceanic crusts between the two blocks subducted northward beneath the southern margin of the yili block in the silurian during the devonian early carboniferous the tarim block rapidly drifted to the north and rotated about 46 clockwise this process induced the collision of the yili micro continent with the eastern segment present geographical position of the tarim continent in the late devonian and the southern tianshan oceanic crust evolved to be a west facing remnant oceanic basin during the late carboniferous early permian the tarim block located within an almost constant latitude range rotated about 26 clockwise with respect to the yili micro continent which ultimately closed the remnant oceanic basin in a scissors like manner from east to west and completed the tarim yili collision subsequent a type subduction of the tarim continental crust and lithosphere scale sinistral shearing generated a magmatic arc on the southern margin of the tarim yili suture zone the late permian early triassic clastics deposited in a peripheral foreland basin developed above the arc

near surface circulation of the nordic seas as measured by lagrangian drifters in the period june 1991 to august 1993 107 argos tracked drifters drogued to 15 m depth were released in the nordic seas or greenland iceland and norwegian seas the drifter movements revealed the strong and spatially confined current systems along the surface salinity fronts of the iceland faroe frontal zone and of the norwegian coast and along the continental margins and their extensions to the barents sea and spitsbergen the norwegian atlantic current is composed of three distinct streams two continental margin and one coastal branches which join into one single swift mean current west of the lofoten and vesteralen islands where the strongest measured currents are in excess of 110 cm s 1 in addition to the general cyclonic gyre circulation in the nordic seas the drifters indicate smaller cyclonic circulation patterns in all the major subbasins i e the iceland plateau the norwegian the lofoten and the greenland basins no surface signature of the east icelandic current is disclosed by the drifters interpolated and low pass filtered position data were used to construct maps of 15 m depth ensemble mean velocity velocity variability and residence time vigorous eddy fields are dominant in the strong currents and in the lofoten basin eulerian correlations indicate that they tend to propagate to the west in contrast the iceland plateau appears quiescent both in the mean and eddy velocities single particle diffusivities are computed and are found to be in the range 1 7 107 cm2 s 1 the corresponding lagrangian timescale and space scale are 1 3 days and 10 40 km respectively these lagrangian drifter measurements compose the first basin scale accurate near surface velocity data set of the nordic seas

freak waves under typhoon conditions benjamin feir index bfi and directional spread are measures of nonlinearfour wave interactions and resultant indices of possible conditions for freak waves temporal spatial distributions of bfi and directional spread are examined with numericalsimulations of a spectral wave model using typhoon conditions the spatial distributionsof wave characteristics such as significant wave height wave period bfi and directionalspread are different from each other around the eye of the typhoon bfi is significantlylarge in the fourth quadrant of the typhoon while waves are steep and have narrowfrequencies and directional spectra freak waves resulting from nonlinear four wave waveinteractions have a greater potential of occurring in the fourth quadrant of the typhoonthan in the other quadrants furthermore crossing sea states from two wind wave systemscan be observed behind the eye of the typhoon the crossing two wind systems arealso dangerous sea states although as observed they are closer to linear wave conditions finally the characteristics of possible freak wave conditions during typhoons areverified with field data

the enya mounds a lost mound drift competition the genesis and evolution of cold water coral banks along the northeastern atlantic margin is known to be influenced by several factors among which the palaeotopography and nature of the coral settling surface the presence of bottom currents and sediment supply in this paper a case study is presented of the enya mound cluster located in the southernmost tip of the belgica mound province west of ireland below this mound cluster seismic stratigraphy revealed a yet unmapped local unconformity rd1b being part of a composite erosion event rd1 as such from the late miocene to late pliocene at least two erosional events have incised the margin ending with the final rd1a moundbase unconformity acting as a base for the enya mounds during the quaternary the mounds became outgrown and were covered by a mounded contourite drift in addition they are closely associated with a cluster of seabed pockmarks the bottom current regime which became active since the middle pleistocene has certainly influenced the fate of this mound cluster the occurrence of the pockmarks seems to be related to relatively recent fluid migration processes however leaving an open question if any previous seepage phases were involved in the growth or initiation of the coral banks

gravity anomalies flexure of the indian plate and the structure support and evolution of the himalaya and ganga basin bouguer gravity anomalies along four profiles across the western himalaya and ganga basin show large deviations from local isostatic equilibrium a deficit of mass characterizes the ganga basin and an excess underlies the lesser himalaya both can be understood if the indian plate is flexed down by the distributed load of part of the mountains the cross sectional shape of the ganga basin seems to be controlled by the deflection of the indian plate which we compute assuming the indian plate to overlie an inviscid fluid from the shapes of both bouguer anomaly profiles and the basement topography we place bounds on the flexural rigidity of such a plate if the ganga basin is a steady state feature then the age of the basal sediments in a given locality should be proportional to the distance of that locality from the southern edge of the basin if the rate of convergence of india and the himalaya were constant that rate should equal the distance divided by the corresponding age we find a rate of 10 to 15 mm a for the last 15 to 20 ma which is consistent with a large part of the 50 mm a rate of convergence between india and eurasia being absorbed by the eastward extrusion of parts of tibet profiles of bouguer gravity anomalies show only a small peak or plateau over the southern edge of the lesser himalaya implying that the boundary between the light sediments of the ganga basin and the heavier crustal rocks of the lesser himalaya is not sharp and that there exists some light material beneath the range we infer that some sediment deposited in the ganga basin has been underthrust beneath the lesser himalaya but the quantity is small most of this sediment probably is scraped off the indian plate to make the foothills of the range we find that the load of the high himalaya is too large to be supported solely by elastic stress in the indian plate if the flexural rigidity of the plate is constant and if no other external forces act on the plate the observed gradient in bouguer gravity anomalies increases from an average of about 1 mgal km over the ganga basin and lesser himalaya to about 2 mgal km over the high himalaya this increase in the gravity gradient implies that the moho dips more steeply 10 15 beneath the high himalaya than beneath the lesser himalaya 2 3 we interpret this steepening of the moho to be due to a weakening of the plate which allows it to bend more sharply beneath the high himalaya than farther south with the inclusion of a weak segment of indian plate beneath the high himalaya calculated anomalies show a somewhat increased gradient beneath the high himalaya but when the weight of the entire himalaya is used as a load on the plate calculated anomalies are more negative than observed therefore an external force system is needed to support much of the weight of the high himalaya as well as to bend the plate sufficiently beneath the high himalaya the magnitudes of the bending moment and the force per unit length that must be applied to the end of the plate are compatible with their sources being gravity acting on a part of india s mantle lithosphere stripped of its crust and underthrust beneath southern tibet

glacial cold water coral growth in the gulf of cadiz implications of increased palaeo productivity a set of 40 uranium series datings obtained on the reef forming scleractinian cold water corals lophelia pertusa and madrepora oculata revealed that during the past 400 kyr their occurrence in the gulf of cadiz goc was almost exclusively restricted to glacial periods this result strengthens the outcomes of former studies that coral growth in the temperate ne atlantic encompassing the french iberian and moroccan margins dominated during glacial periods whereas in the higher latitudes irish and norwegian margins extended coral growth prevailed during interglacial periods thus it appears that the biogeographical limits for sustained cold water coral growth along the ne atlantic margin are strongly related to climate change by focussing on the last glacial interglacial cycle this study shows that palaeo productivity was increased during the last glacial this was likely driven by the fertilisation effect of an increased input of aeolian dust and locally intensified upwelling after the younger dryas cold event the input of aeolian dust and productivity significantly decreased concurrent with an increase in water temperatures in the goc this primarily resulted in reduced food availability and caused a widespread demise of the formerly thriving coral ecosystems moreover these climate induced changes most likely caused a latitudinal shift of areas with optimum coral growth conditions towards the northern ne atlantic where more suitable environmental conditions established with the onset of the holocene

major temporal variations in shortening rate absorbed along a large active fold of the southeastern tianshan piedmont china the investigation of deformation rates on a mountain piedmont can provide key information for improving our understanding of the overall dynamics of a mountain range here we estimate the shortening rate absorbed by a quaternary emergent detachment fold on the southeastern piedmont of the tianshan china our work is primarily based on new 10be cosmogenic exposure dating of deformed alluvial surfaces the method we have developed combines depth profiling with sampling of surface cobbles thereby allowing exposure time erosion rate and inheritance to be simultaneously constrained the exposure ages of the uppermost uplifted alluvial surfaces are around 140 17 ka140 17 ka 130 9 ka130 9 ka and 47 9 ka47 9 ka from west to east a terrace lying below the 140 ka surface is dated at 65 5 ka65 5 ka the ages of the uplifted and folded alluvial surfaces were then combined with estimates of shortening obtained using two distinct methods 1 the excess area method where sedimentation rates extracted from magnetostratigraphic studies are used to determine the amount of sedimentation after the abandonment of the river and 2 a folding model derived from sandbox experiments the late pleistocene shortening rates are shown to be between 0 4 0 1 mm yr0 4 0 1 mm yr and 0 8 0 5 mm yr0 8 0 5 mm yr on the western part of the fold and 2 1 0 4 mm yr2 1 0 4 mm yr along its central part the central part of the frontal yakeng anticline therefore accommodates up to 25 of the total shortening currently absorbed across the whole eastern tianshan range 8 mm yr however this situation seems to have prevailed for only the last 150 ka as the shortening rate absorbed by this nascent fold was previously ten times slower while the initiation of folding of the yakeng anticline can be traced back to 5 5 ma ago the basinward migration of the active deformation front onto the yakeng fold is a relatively recent phenomenon and appears to be diachronous from west to east probably in relation to the tectonic activity of the folds in the hinterland

can swell increase the number of freak waves in a wind sea the effect of a swell on the statistical distribution of a directional short wave field is investigated starting from zakharov s spectral formulation we derive a new modified nonlinear schrodinger equation appropriate for the nonlinear evolution of a narrow banded spectrum of short waves influenced by a swell the swell modified equation is solved analytically to yield an extended version of the result of longuet higgins stewart j fluid mech vol 8 no 4 1960 pp 565 583 for the modulation of a short wave riding on a longer wave numerical monte carlo simulations of the long term evolution of a spectrum of short waves in the presence of a monochromatic swell are employed to extract statistical distributions of freak waves among the short waves we find evidence that a realistic short crested wind sea can on average experience a small increase in freak wave probability because of a swell provided the swell is not orthogonal to the wind waves for orthogonal swell and wind waves we find evidence that there is almost no significant change in the probability of freak waves in the wind sea if the short waves are unrealistically long crested such that the benjamin feir index serves as indicator for freak waves gramstad trulsen j fluid mech vol 582 2007 pp 463 472 it appears that the swell has much smaller relative influence on the probability of freak waves than in the short crested case

cold water corals are they hydrocarbon seep related numerous cold water ahermatypic coral reefs so called lophelia reefs up to 30m high 150m wide and 400m long occur at waterdepths from 100 to 350 m off mid norway after the discovery of relatively high interstitial methane concentrations 204 ppb in sediments collected at the base of one of these reef structures a causative link between the presence of the reefs and local micro seepage through seabed of light hydrocarbons is here suggested shallow seismic records gathered across this and other reef colonies off mid norway also indicate the existence of gas charged sediments below the reefs

preboreal onset of cold water coral growth beyond the arctic circle revealed by coupled radiocarbon and u series dating and neodymium isotopes cold water coral mounds of lophelia pertusa are widespread across the scandinavian shelf which was completely ice covered during the last glacial maximum between 22 to 18 ka bp rapid deglacial meltdown of the fennoscandian inland ice and the retreat of its ice streams freed most of the shelf of ice by 15 ka bp however cold water coral growth commenced only after the pleistocene holocene transition at 11 65 ka bp when modern like climatic patterns and oceanographic conditions were established a tight climatic coupling has been constrained with u series ages coupled 14c ages provide local reservoir ages from various gravity cores in a fjord setting in stjernsund at 70 n and on the open shelf in traenadjupet at 66 n reinvestigation of earlier 14c coral chronologies suggests that coral ecosystems widely established themselves across the entire 3000 km long scandinavian shelf prior to 10 ka bp the earliest occurrence of madrepora oculata at 2 4 ka bp suggests a late holocene colonization of the norwegian shelf which is linked to a prominent mound growth hiatus in traenadjupet 64 n mound growth rates near the northern biogeographic boundary of l pertusa with up to 614 cm ka 1 during certain growth periods are much higher than the previously reported fastest rates of 220 cm ka 1 from the irish margin contemporaneous rapid fjordbasin sedimentation is slower with 63 cm ka 1 matrix 14c ages overlap with coral 14c ages from the same horizon this indicates rapid framework construction and efficient trapping of background sediment hiatuses are frequent in on mound sediments and only short periods of coral growth are recorded coupled 14c and end values indicate a persistent holocene inflow of the north atlantic current in stjernsund but also deglacial meltwater mixing during the early holocene prior to 9 5 ka bp reservoir ages are overall close to the surface marine reservoir age but r is highly localized

gps velocity field for the tien shan and surrounding regions 1 measurements at 400 campaign style gps points and another 14 continuously recording stations in central asia define variations in their velocities both along and across the kyrgyz and neighboring parts of tien shan they show that at the longitude of kyrgyzstan the tarim basin converges with eurasia at 20 2 mm yr nearly two thirds of the total convergence rate between india and eurasia at this longitude this high rate suggests that the tien shan has grown into a major mountain range only late in the evolution of the india eurasia collision most of the convergence between tarim and eurasia within the upper crust of the tien shan presumably occurs by slip on faults on the edges of and within the belt but 1 3 mm yr of convergence is absorbed farther north at the dzungarian alatau and at a lower rate with the kazakh platform to the west the tarim basin is thrust beneath the tien shan at 4 7 mm yr with respect to eurasia the ferghana valley rotates counterclockwise at 0 7 myr 1 about an axis at the southwest end of the valley thus gps data place a bound of 4 mm yr on the rate of crustal shortening across the chatkal and neighboring ranges on the northwest margin of the ferghana valley and they limit the present day slip rate on the right lateral talas ferghana fault to less than 2 mm yr gps measurements corroborate geologic evidence indicating that the northern margin of the pamir overthrusts the alay valley and require a rate of at least 10 and possibly 15 mm yr

impact of synkinematic sedimentation on the geometry and dynamics of compressive growth structures insights from analogue modelling analogue sandbox models have been set up to study the impact of synkinematic deposits on the geometry and evolution of single thrusts and folds according to different sedimentation modes a slow or rapid sedimentation rate that is constant or changing in space and time and rheological profiles thin or thick sedimentary series with or without a basal decollement level a first series of experiments documents the influence of synkinematic deposits according to their sedimentation rate and the rheology of the prekinematic materials a second series investigates the influence of changes in the sedimentation rate through time a third one considers the influence of changes in the sedimentation rate in space all these experiments suggest that the geometry and evolution of single compressive growth structures vary according to the sedimentation rate the number and dip of their frontal thrust segments change with the ratio r between the sedimentation rate at the footwall of the faults and the uplift rate of their hanging wall the latter is then more or less uplifted depending on the dip of the thrusts as a result the overall structure has either a fault bend fold or a fault propagation fold geometry these rules are verified when the ratio r changes in space or through time in addition the rheological profile of the models also affects the geometry and evolution of compressive growth structures their structural style as well as the synsedimentary splitting and steepening of the associated thrusts varies according to the occurrence and strength of the brittle and ductile layers according to this modelling study the ratio r and its changes in space and time along with the rheology of the deformed materials are key parameters to better understand the geometrical and kinematical complexities of natural growth thrusts and folds and to improve their interpretation

temporal constraints and pulsed late cenozoic deformation during the structural disruption of the active kashi foreland northwest china 1 in response to the ongoing indo asian collision structural deformation has encroached into the tian shan foreland in western china since the early miocene in order to reconstruct a detailed history of foreland deformation along the southern margin of the tian shan we have synthesized extensive mapping analysis of seismic sections magnetostratigraphy of the foreland fill and associated growth strata apatite fission track dating changes in sediment accumulation rates and geodetic surveys of deformed fluvial terraces across an area exceeding 6500 km2 that spans the kashi foreland in the northwestern tarim basin we use these data to place temporal constraints on individual structures that delineate at least 4 distinct stages of deformation stage 1 involved initial uplift of hinterland structures beginning at 20 25 ma stage 2 began at 16 3 ma when the basement involved deformation front stepped south to the kashi basin thrust that bounds the foredeep strata stage 3 occurred from 13 5 to 4 ma as the deformation front migrated south in episodic steps above thin skinned detachment and ramp flat folding finally stage 4 began after 4 ma with growth of the keketamu anticline followed by rapid southward migration of the deformation front to the atushi and then kashi detachment anticlines on the basis of the deformed tertiary strata and available seismic data calculations of the minimum magnitude of shortening yield totals ranging from 10 to 32 km since the early miocene of which 7 12 km occurred since 4 ma although average shortening rates since 16 3 ma were 0 8 1 3 mm a rates were faster from 16 3 to 13 5 ma 1 1 3 2 mm a after which they decreased to 0 5 mm a between 13 5 and 4 ma before increasing to 2 2 2 7 mm a after 4 ma similarly the rate of southward propagation of the deformation front was initially 3 7 mm a for the first 10 ma of basin development slowed to 1 5 mm a between 13 5 and 4 ma and increased to more than 10 mm a since 4 ma these changes in shortening and structural migration rates over time suggest that the loci of orogenic deformation shifted in and out of the foreland during the neogene surveyed stream terraces suggest that although most current deformation is located along the southern front of the foreland modest deformation and shortening continue in the hinterland structural style within the foreland has also changed over time from imbricate thrust faults with hanging wall folds along the northern margin to ramp flat faults and detachment folds along the southern margin where the basement rocks are previously deformed such as in the hinterland of the kashi foreland thick skinned fault ramps and related fault propagation folds dominate the structural style as syntectonic sedimentation within the foreland produced thick subhorizontal stratigraphy the structural style evolved to detachment and fault bend folding above these footwall flats within the neogene strata

the moira mounds small cold water coral banks in the porcupine seabight ne atlantic part a an early stage growth phase for future coral carbonate mounds this paper presents a comprehensive overview of the moira mounds in the porcupine seabight combining a review of currently published material with new data and interpretations the moira mounds are circular to ovoid shaped individual or clustered coral banks referred to as scleractinian spaced cluster macroreefs located in the belgica carbonate mound province porcupine seabight west of ireland they are up to 10 m high and 20 to 35 m in diameter for the first time a map showing the complete extent and location of the moira mounds is published revealing 256 examples grouped into four areas mainly between 800 and 1100 m water depth rov groundtruthing revealed the importance of bedload sand transport in moira mound formation and development processes through sediment entrapment by coral frameworks lophelia pertusa and madrepora oculata new estimated growth rates for the moira mounds are comparable to those measured for much larger irish coral carbonate mounds but an order of magnitude lower than rates from comparably sized reefs offshore norway as well as the framework corals 26 macrobenthic invertebrate species were identified from a single box core that were similar to those communities found in adjacent off mound habitats it is proposed that the moira mounds are an example of the early stage growth phase of nearby giant coral carbonate mounds and represent a westward extension of the zone of active cold water coral mound growth and therefore a deepening of the zone of cold water coral growth over recent climate cycles

paleozoic tectonic evolution of the tianshan orogen northwestern china abstract the chinese tianshan orogenic belt which extends west east for about 1500 km is one of the most important paleozoic orogenic belts in central asia it includes parts of the tarim yili central tianshan and junggar plates which are microcontinental blocks with precambrian basements and meso cenozoic depositional covers the tarim plate is separated from the yili central tianshan plate by the southern central tianshan suture early carboniferous ophiolitic melanges and blueschists are widespread in this suture and are believed to be produced by the collision between a passive continental margin on the north side of the tarim plate and an active continental margin on the south side of the yili central tianshan plate the collision occurred at the end of early carboniferous the yili central tianshan and the junggar plates are separated by the northern central tianshan suture also considered as an early carboniferous collisional zone along which the middle ordovician ophiolitic melanges blueschists and late devonian early carboniferous ophiolites are exposed in early paleozoic times the subduction of the paleo junggar ocean took place in an active margin on the north side of the yili central tianshan plate along the northern central tianshan suture at the end of early carboniferous the north side of the yili central tianshan plate collided with the north tianshan arc along this suture the paleo oceanic crust in the tianshan and adjacent region was entirely consumed at the end of early carboniferous meanwhile the tarim yili central tianshan and junggar plates were accreted to eurasia epicontinental sediments were then deposited throughout the tianshan region during the middle late carboniferous times in the early permian tianshan began to uplift with accompanying volcanic eruption and granitic intrusion the uplift was accelerated in the late permian and continental molasse was extensively deposited

modeling the shortening history of a fault tip fold using structural and geomorphic records of deformation 1 we present a methodology to derive the growth history of a fault tip fold above a basal detachment our approach is based on modeling the stratigraphic and geomorphic records of deformation as well as the finite structure of the fold constrained from seismic profiles we parameterize the spatial deformation pattern using a simple formulation of the displacement field derived from sandbox experiments assuming a stationary spatial pattern of deformation we simulate the gradual warping and uplift of stratigraphic and geomorphic markers which provides an estimate of the cumulative amounts of shortening they have recorded this approach allows modeling of isolated terraces or growth strata we apply this method to the study of two fault tip folds in the tien shan the yakeng and anjihai anticlines documenting their deformation history over the past 6 7 myr we show that the modern shortening rates can be estimated from the width of the fold topography provided that the sedimentation rate is known yielding respective rates of 2 15 and 1 12 mm yr across yakeng and anjihai consistent with the deformation recorded by fluvial and alluvial terraces this study demonstrates that the shortening rates across both folds accelerated significantly since the onset of folding it also illustrates the usefulness of a simple geometric folding model and highlights the importance of considering local interactions between tectonic deformation sedimentation and erosion

diagenetic formation of gypsum and dolomite in a cold water coral mound in the porcupine seabight off ireland authigenic gypsum was found in a gravity core retrieved from the top of mound perseverance a giant cold water coral mound in the porcupine basin off ireland the occurrence of gypsum in such an environment is intriguing because gypsum a classic evaporitic mineral is undersaturated with respect to sea water sedimentological petrographic and isotopic evidence point to diagenetic formation of the gypsum tied to oxidation of sedimentary sulphide minerals i e pyrite this oxidation is attributed to a phase of increased bottom currents which caused erosion and enhanced inflow of oxidizing fluids into the mound sediments the oxidation of pyrite produced acidity causing carbonate dissolution and subsequently leading to pore water oversaturation with respect to gypsum and dolomite calculations based on the isotopic compositions of gypsum and pyrite reveal that between 21 6 and 28 6 of the sulphate incorporated into the gypsum derived from pyrite oxidation the dissolution of carbonate increased the porosity in the affected sediment layer but promoted lithification of the sediments at the sediment water interface thus authigenic gypsum can serve as a signature for diagenetic oxidation events in carbonate rich sediments these observations demonstrate that fluid flow steered by environmental factors has an important effect on the diagenesis of coral mounds

enhanced freak wave occurrence with narrow directional spectrum in the north sea 1 wind and wave records obtained from the kvitebjorn platform 2 3 e 61 0 n 190 m deep in the northern north sea from 2003 to 2005 were analyzed among the 2723 20 min records taken during storm conditions 57 cases included freak waves exceeding twice the significant wave height comparisons between various wave parameters and the freak wave occurrence index did not show any significant correlation thus the in situ wave record was used to select the days when relatively more or less freak waves were observed the days were classified into freakish and non freakish days respectively on freakish days the icelandic low was enhanced hindcasts performed by a third generation wave model suggest that this synoptic atmospheric pressure difference produces approximately 7 6 degrees narrower directional spreading of the wave spectra during freakish days at the kvitebjorn platform this result is consistent with the physical mechanism of freak wave generation through nonlinear self focusing in random wave fields

paleoseismology of the northern piedmont of tianshan mountains northwestern china the northern piedmont of the tianshan mountains consists of three rows of cenozoic ew striking fold and reverse fault zones with en echelon right lateral steps the southernmost row involves sediments as young as lower pleistocene but there is no evidence of activity along this row during the last 30 000 years the central row is composed of three linear anticlines houerguos manas and tugulu and associated reverse faults the northernmost row includes the dushanzi halaande and anjihai anticlines and their associated reverse faults abundant fault scarps and folds of late pleistocene to holocene river terraces across the anticlines within the central and the northernmost rows indicate recent folding and reverse faulting we divide the northern piedmont into the dushanzi and manas fold and reverse fault zone in the dushanzi zone we excavated 15 trenches across scarps controlled by reverse faults and back thrusts by comparing 11 trench logs among the 15 trenches we identify three paleoearthquakes since 13 000 years b p the first event occurred between 11 300 and 13 300 years b p and the second and the third events occurred 6300 8400 and 3000 5000 years b p respectively considering the uncertainties of the data the average recurrence interval for large earthquakes in the dushanzi zone is about 4000 years a large earthquake along this zone is expected in the near future because the elapsed time since the last surface rupturing event is already 3000 4000 years three large trenches and several small trenches excavated across the fault scarps along the manas fold and reverse fault zone reveal four events the first second and third events occurred at 18 000 13 000 years b p 11 300 10 500 years b p and 6900 3600 years b p respectively the fourth the latest one is the 1906 m 7 7 manas earthquake field investigation suggests that the 1906 manas earthquake occurred along a blind thrust fault this earthquake formed three discontinuous zones of fresh surface ruptures the longest of which is only 8 km long along the eastern segment of the tugulu reverse fault and was associated with a zone of uplift 130 km long related to the manas earthquake the average recurrence interval along this zone is probably 5000 6000 years therefore it is unlikely that a large earthquake will occur along this zone in the near future because the manas earthquake occurred only 89 years ago

fluvial incision and tectonic uplift across the himalayas of central nepal the pattern of fluvial incision across the himalayas of central nepal is estimated from the distribution of holocene and pleistocene terraces and from the geometry of modern channels along major rivers draining across the range the terraces provide good constraints on incision rates across the himalayan frontal folds sub himalaya or siwaliks hills where rivers are forced to cut down into rising anticlines and have abandoned numerous strath terraces farther north and upstream in the lesser himalaya prominent fill terraces were deposited probably during the late pleistocene and were subsequently incised the amount of bedrock incision beneath the fill deposits is generally small suggesting a slow rate of fluvial incision in the lesser himalaya the terrace record is lost in the high range where the rivers are cutting steep gorges to complement the terrace study fluvial incision was also estimated from the modern channel geometries using an estimate of the shear stress exerted by the flowing water at the bottom of the channel as a proxy for river incision rate this approach allows quantification of the effect of variations in channel slope width and discharge on the incision rate of a river the determination of incision rates requires an additional lithological calibration the two approaches are shown to yield consistent results when applied to the same reach or if incision profiles along nearby parallel reaches are compared in the sub himalaya river incision is rapid with values up to 10 15 mm yr it does not exceed a few millimeters per year in the lesser himalaya and rises abruptly at the front of the high range to reach values of 4 8 mm yr within a 50 km wide zone that coincides with the position of the highest himalayan peaks sediment yield derived from the measurement of suspended load in himalayan rivers suggests that fluvial incision drives hillslope denudation of the landscape at the scale of the whole range the observed pattern of erosion is found to closely mimic uplift as predicted by a mechanical model taking into account erosion and slip along the flat ramp flat geometry of the main himalayan thrust fault the morphology of the range reflects a dynamic equilibrium between present day tectonics and surface processes the sharp relief together with the high uplift rates in the higher himalaya reflects thrusting over the midcrustal ramp rather than the isostatic response to reincision of the tibetan plateau driven by late cenozoic climate change or late miocene reactivation of the main central thrust

magnetostratigraphy and rock magnetism of the neogene kuitun he section northwest china implications for late cenozoic uplift of the tianshan mountains in order to better constrain the tectonic evolution of central asia under the influence of the india asia collision we carried out a magnetostratigraphic study at the kuitun he section on the northern flank of the tianshan range northwest china a total of 801 samples were collected from a 1559 m thick section which is composed mainly of fluvio lacustrine sandstone and conglomerate stepwise thermal and alternating field demagnetization isolated a linear magnetization component that decays univectorally toward the origin and likely represents a primary magnetization principally carried by magnetite from this component 29 magnetic polarity intervals were identified they correlate between 3 1 and 10 5 ma with the reference magnetic polarity time scale indicating a relatively constant sedimentation rate with an average of 0 21 0 01 mm year we also performed a suite of rock magnetic experiments designed to track time transgressive changes in the sedimentary record from the rock magnetic parameters together with the constant sedimentation rate we conclude that the tianshan mountains were actively uplifting by 10 5 ma

rogue waves in crossing seas the louis majesty accident 1 we analyze the sea state conditions during which the accident of the cruise ship louis majesty took place the ship was hit by a large wave that destroyed some windows at deck number five and caused two fatalities using the wave model wam driven by the consortium for small scale modelling cosmo me winds we perform a detailed hindcast of the local wave conditions the results reveal the presence of two comparable wave systems characterized almost by the same frequency we discuss such sea state conditions in the framework of a system of two coupled nonlinear schrodinger cnls equations each of which describe the dynamics of a single spectral peak for some specific parameters we discuss the breather solutions of the cnls equations and estimate the maximum wave amplitude even though due to the lack of measurements it is impossible to establish the nature of the wave that caused the accident we show that the angle between the two wave systems during the accident was close to the condition for which the maximum amplitude of the breather solution is observed

the origin of deep water coral topped mounds in the northern rockall trough northeast atlantic mounds associated with the cold water coral lophelia pertusa are widespread in the north atlantic although the factors controlling their distribution are not well understood here we examine a group of small coral topped mounds the darwin mounds which occur at 1000 m water depth in the northern rockall trough northwest of the uk individual mounds are up to 75 m in diameter and 5 m high although some mound like targets seen on sidescan sonar have little or even negative relief some mounds are associated with tail like features imaged as elongate patches of moderate backscatter up to 500 m long elongated parallel to prevailing bottom currents high resolution sidescan images and seabed photographs show hundreds of coral colonies each a metre or so across on each individual mound many other organisms mainly suspension feeders occur in association with the coral piston cores from the mounds contain predominantly quartz sand with only scattered coral fragments showing that bioclastic material is not a major contributor to mound building a field of seabed pockmarks occurs immediately south of the darwin mounds on sidescan sonar data pockmarks are low relief circular depressions typically around 50 m in diameter the seafloor around the pockmarks consists of uniform heavily burrowed muddy sediments and no specific biological communities nor any sedimentological or photographic evidence for active seepage were observed the distribution of mounds and pockmarks suggests a gradual transition from mounds in the north to pockmarks in the south this combined with the lack of bioclastic material in the mound sediments suggests that both mounds and pockmarks are created by fluid escape from below the seafloor mounds occur where fluids carry subsurface sand to the surface where it forms mounds because bottom currents are not strong enough to disperse it pockmarks form where muddy material is eroded by fluid escape but dispersed by bottom currents despite the origin of mounds through fluid escape we suggest that it is the elevated mound topography rather than any fluid escape that is advantageous to the corals this is supported 1 by the wide variety of suspension feeding organisms that occur on the mounds since all of these are unlikely to have a specialised seepage related lifestyle and 2 because corals and their associated community do not occur around pockmarks where seepage has also occurred but elevated topography is absent

a fluvial terrace record of late quaternary folding rate of the anjihai anticline in the northern piedmont of tian shan china abstract crustal shortening of the tian shan range in northwest china has largely been accommodated by fold and thrust belts that mark the northern and southern mountain boundaries which were formed during the basinward propagation of the deformation front of tian shan investigating the deformation rates of active folds anticlines in the mountain piedmonts within different timescales is important for understanding the mountain building and front propagation processes of the tian shan in this study we investigate the late quaternary folding rate of the anjihai anticline one of the major anticlines in the northern piedmont of tian shan our study is based on optically stimulated luminescence osl dating and topographic measurements of folded river terraces three well preserved fluvial terraces across the anjihai anticline were identified and dated to be 3 6 0 1 ka 9 0 0 6 ka and 53 3 2 2 ka respectively these terrace ages are combined with shortening and uplift of the terraces estimated using an area conservation method and the terrace height profiles to evaluate the average shortening and uplift rates our results show that the minimum shortening rate of the anjihai anticline is 0 4 mm a between 53 ka and 9 ka and 1 1 mm a over the past 9 ka and the corresponding minimum uplift rates are 0 5 mm a and 1 4 mm a respectively if a local sedimentation rate of 0 3 mm a is taken into consideration the shortening rate is 0 7 mm a between 53 ka and 9 ka and 1 3 mm a since 9 ka and the corresponding uplift rates are 0 8 mm a and 1 5 mm a respectively these data suggest that the anjihai anticline has accommodated 20 25 of the total shortening across the whole eastern tian shan 5 mm a in the holocene our results suggest that the holocene is a relatively tectonically active time interval since the late pleistocene the late quaternary shortening rate of the anjihai anticline is much higher than its long term average shortening rate 0 2 mm a since its formation at 7 4 ma a similar situation has also been observed for other active folds in the northern and southern piedmonts of tian shan the higher late quaternary folding rate is possibly attributed to the gradual propagation of the tian shan towards its northern and southern foreland basins in the quaternary

evolution of the norwegian current and the scandinavian ice sheets during the past 2 6 m y evidence from odp leg 104 biogenic carbonate and terrigenous records abstract records of biogenic and terrigenous components have been obtained from the interval corresponding to the last 2 6 m y of odp sites 643 and 644 in order to reconstruct surface and deep water regimes in the norwegian sea surface water regimes record long lasting moderate glacial conditions during the interval 2 6 1 0 ma small intrusions of atlantic water episodically penetrated into the norwegian sea forming a narrow tongue along the eastern margin which is documented at site 644 the polar front was most probably situated between the site 644 and 643 locations on the outer voring plateau during these time intervals deep water regimes reflect long term persistent corrosive bottom waters most probably due to a weakly undersaturated water column and a low rate of carbonate shell production in surface waters deep water production in the norwegian greenland sea may have operated in a different way e g brine formation during winter sea ice growth bottom waters were oxygenated throughout the entire period and deep water was exchanged persistently with the north atlantic increased glacial interglacial environmental contrasts are documented reflecting a strengthening of the norwegian current and intensified glaciations on the surrounding land masses during the interval 1 0 0 6 ma during this time a major shift in the mode of deep water production occurred the onset of large amplitudes in glacial interglacial environmental conditions with maximum contrasts in surface water regimes different modes of deep water production and intensified exchange with the north atlantic marks the last 0 6 ma a broad development of the norwegian current is observed during peak interglacials while during glacials seasonally variable sea ice cover and iceberg drift dominate surface water conditions

miocene to present kinematics of fault bend folding across the huerguosi anticline northern tianshan china derived from structural seismic and magnetostratigraphic data we combine surface structural measurements subsurface seismic imaging and magnetostratigraphic dating to retrieve through geometric modeling the detailed history of fold growth and sedimentation across the huerguosi anticline on the northern tianshan piedmont taking advantage of a beautifully exposed section of growth strata the model assumes a fault bend folding mechanism consistent with subsurface fold geometry the shortening history is obtained by least squares fi tting of the measured dip angles of the growth strata the shortening rate across the anticline is shown to have been remarkably constant it increased only slightly from 0 84 0 04 mm yr between 10 and 4 ma to 1 14 0 02 mm yr over the past 4 m y this approach also allows correcting syntectonic sedimentation rates for the effect of the fold growth and shows that the sedimentation rates in the piggyback basin increased abruptly from 0 4 to 0 7 mm yr ca 4 ma

thrust geometry controlled by erosion and sedimentation a view from analogue models analogue sandbox models have been set up to study thrust systems formed above two decollements and affected by erosion and sedimentation the deformation was imaged by x ray scanner three erosion sedimentation conditions were tested for all the experiments a duplex develops between the two decollement levels for the experiment without erosion and without sedimentation ramp anticlines form in the upper series for the model with syntectonic sedimentation and without erosion the shortening in the upper series is first characterized by fault related folds and then by a forward propagation of the decollement that induces the development of a piggy back basin for the experiment with erosion and sedimentation a passive roof duplex is formed relationships between structural style and syntectonic superficial conditions in classical thin skinned thrust belts are similar to those found in the analogue models the ramp anticlines of the jura developed with low erosion and low sedimentation and the large sub andean thrust belt is controlled by syntectonic sedimentation whereas the passive roof duplex of pakistan is synchronized with intense erosion this study outlines the crucial effect of the superficial mass transport phenomena in the tectonic style of thrust belts

the importance of the terrigenous fraction within a cold water coral mound a case study in the nineties cold water coral mounds were discovered in the porcupine seabight ne atlantic west of ireland a decade later this discovery led to the drilling of the entire challenger cold water coral mound eastern slope porcupine seabight during iodp expedition 307 as more than 50 of the sediment within challenger mound consists of terrigenous material the terrigenous component is equally important for the build up of the mound as the framework building corals moreover the terrigenous fraction contains important information on the dynamics and the conditions of the depositional environment during mound development in this study the first in depth investigation of the terrigenous sediment fraction of a cold water coral mound is performed combining clay mineralogy sedimentology petrography and sr nd isotopic analysis on a gravity core md01 2451g collected at the top of challenger mound sr and nd isotopic fingerprinting identifies ireland as the main contributor of terrigenous material in challenger mound besides this a variable input of volcanic material from the northern volcanic provinces iceland and or the nw british isles is recognized in most of the samples this volcanic material was most likely transported to challenger mound during cold climatic stages in three samples the isotopic ratios indicate a minor contribution of sediment deriving from the old cratons on greenland scandinavia or canada the grain size distributions of glacial sediments demonstrate that ice rafted debris was deposited with little or no sorting indicating a slow bottom current regime in contrast interglacial intervals contain strongly current sorted sediments including reworked glacio marine grains the micro textures of the quartz sand grains confirm the presence of grains transported by icebergs in interglacial intervals these observations highlight the role of ice rafting as an important transport mechanism of terrigenous material towards the mound during the late quaternary furthermore elevated smectite content in the siliciclastic glaciomarine sediment intervals is linked to the deglaciation history of the british irish ice sheet biis the increase of smectite is attributed to the initial stage of chemical weathering processes which became activated following glacial retreat and the onset of warmer climatic conditions during these deglaciations a significant change in the signature of the detrital fraction and a lack of coral growth is observed therefore we postulate that the deglaciation of the biis has an important effect on mound growth it can seriously alter the hydrography nutrient supply and sedimentation processes thereby affecting both sediment input and coral growth and hence coral mound development

relatively recent construction of the tien shan inferred from gps measurements of present day crustal deformation rates the tien shan a high seismically active intracontinental mountain belt 1 000 2 000 km north of the himalaya has grown as a result of india s collision with asia1 the crustal shortening 200 50 km refs 2 3 and thickening that gave rise to the tien shan accommodates only a small fraction of india s total penetration into asia 2 000 3 000km and the temporal relationship of deformation in this belt to the india asia collision remains unclear here we report geodetic measurements of the tien shan using the global positioning system gps that indicate that the current crustal shortening rate is nearly half of india s convergence rate with eurasia in this area4 we infer a total shortening rate for the tien shan of 20 mm yr 1 which is approximately twice that inferred previously from the extrapolation of slip rates in the holocene3 and earthquake induced displacements during this century5 suggesting that the rate of mountain building in this region has accelerated several fold since the onset of collision 50 55 myr ago6 7 if as we argue the current shortening rate can be extrapolated to geological timescales then our results suggest that most of the tien shan has been constructed during the past 10 myr perhaps in response to an increased horizontal force following an abrupt rise of the tibetan plateau8 9

grounding pleistocene icebergs shape recent deep water coral reefs the widespread view that scleractinian corals in cold and deep waters of high latitudes are slow growing organisms that do not form reefs is challenged by the discovery of a huge coral reef over 13 km in length 10 to 35 m in height and up to 300 m in width formed by the coral lophelia pertusa in water depths of 270 to 310 m at 64 n on the sula ridge mid norwegian shelf cruises in 1994 1995 and manned submersible operations in may 1997 provide data and observations from which the structure and development of the sula ridge coral reef have been determined the fennoscandian icesheet retreated from the mid norwegian shelf prior to 12 000 years before present and modern oceanographic conditions were established at 8000 years before present coral growth since that time has resulted in a large deep water shelf reef for which recent stable isotopic studies have demonstrated high growth rates for these azooxanthellate cold water corals information on the geometry of deep water coral reefs and their environmental controls is still fragmentary controversial and raises issues of conservation in this area of active fishing and oil exploration this paper reports on the discovery of what is probably one of the largest deep water coral reefs existing in the northeast atlantic and indicates that its siting is due to post glacial structures iceberg plough marks events the second storegga slide and local conditions on the seafloor surprisingly reef accumulation rates on the sula ridge are comparable with those measured on tropical coral reefs

space time extremes in short crested storm seas abstractthis study develops a stochastic approach to model short crested stormy seas as random fields both in space and time defining a space time extreme as the largest surface displacement over a given sea surface area during a storm associated statistical properties are derived by means of the theory of euler characteristics of random excursion sets in combination with the equivalent power storm model as a result an analytical solution for the return period of space time extremes is given subsequently the relative validity of the new model and its predictions are explored by analyzing wave data retrieved from noaa buoy 42003 located in the eastern part of the gulf of mexico offshore naples florida the results indicate that as the storm area increases under short crested wave conditions space time extremes noticeably exceed the significant wave height of the most probable sea state in which they likely occur and that they also do not violate stokes miche type upper limits on wave heights

quaternary folding of the eastern tian shan northwest china abstract the tian shan east west trending more than 2000 km is one of most active intracontinental mountain building belts that resulted from india eurasia collision during cenozoic in this study quaternary folding related to intracontinental mountain building of the tian shan orogenic belt is documented based on geologic interpretation and analyses of the satellite remote sensing images landsat thematic mapper tm enhanced thematic mapper etm and india remote sensing irs pan combined with field geologic and geomorphic observations and seismic reflection profiles analyses of spatial temporal features of quaternary folded structure indicate that the early quaternary folds are widely distributed in both piedmont and intermontane basins whereas the late quaternary active folds are mainly concentrated on the northern range fronts field observations indicate that quaternary folds are mainly characterized by fault related folding the formation and migration of quaternary folding are likely related to decollement surfaces beneath the fold and fault zone as revealed by seismic reflection profiles moreover analysis of growth strata indicates that the quaternary folding began in late stage of early pleistocene 2 1 1 2 ma finally tectonic evolution model of the quaternary deformation in the tian shan is presented this model shows that the quaternary folding and faulting gradually migrate toward the range fronts due to the continuous compression related to india eurasia collision during quaternary time as a result the high topographic relief of the tian shan was formed