observed cross shelf flow induced by mesoscale eddies in the northern south china sea abstractcross shelf flow induced by mesoscale eddies has been investigated in the northern south china sea nscs using velocity observations from long ranger adcp moorings mesoscale eddies influe

mesoscale eddies in the south china sea observed with altimeter data 1 a composite time series 1993 2000 of sea surface height anomaly from several satellites is used to identify eddies in the south china sea scs the eddy lifetime radius strength and straight line travel distance are estimated altogether 58 anticyclonic eddies and 28 cyclonic eddies are identified for this period they are grouped into four geographical zones according to known eddy generation mechanisms and their statistics are discussed accordingly our geographical classification is a useful first step in gaining an overview of their generation

isotopic tracers of nitrogen from atmospheric deposition to coastal waters nitrogen deposition to global oceans from the atmosphere can be about two times that of natural riverine input see duce et al 1991 for recent comprehensive review even accounting for the increased loading of riverine nitrogen by anthropogenic inputs total atmospheric deposition ad is essentially equal to that of riverine sources among growth limiting nutrients nitrogen plays a key role in regulating primary and secondary productivity both on regional and global scales e g ryther and dunstan 1971 nixon et al 1986 as such proper identification and characterization of nitrogen sources and their impacts on nutrient flux and trophic utilization is of prime concern in understanding biogeochemical responses in coastal ecosystems eppley and peterson 1979 paerl 1985 legendre and gosselin 1989 ad represents a quantitatively important but poorly assessed nitrogen source in these ecosystems paerl 1985 fisher et al 1988 prado fiedler 1990 loye pilot et al 1990 current estimates indicate that from 20 to as much as 50 of annual new nitrogen loading is attributable to ad alone in geographically diverse coastal regions including those along the u s eastern seaboard fisher et al 1988 even among large bodies of water such as the baltic and mediterranean seas ad constitutes a highly significant n source pradofiedler 1990 loye pilot et al 1990 in north carolina s adjacent coastal atlantic waters ad is a major source 35 80 of new nitrogen assumptions for this type of calculation include the following 1 advective input of n from gulf stream is very low 2 no upwelling is occurring and 3 n2 fixation accounts for no more than 10 of new n inputs here ad has been shown to significantly stimulate primary production by as much as 50 200 at natural input levels paerl 1985 paerl et al 1990 the need to have a more detailed understanding of the impacts of ad of nitrogen in coastal waters is pressing because previouslypristine segments of the coastal oceans are now exhibiting both incipient and advanced stages of eutrophication nitrogen from ad may be a unique nutrient source in the coastal zone for two reasons firstly direct surface water deposition as wet and dryfall frequently occurs downstream of oligoand mesohaline estuarine nutrient stripping regions that assimilate a majority ofterrigenous n inputs boynton et al 1982 sharp et al 1984 in shallow coastal areas such as those present along the mid atlantic states dilution of ad is minimized which amplifies its importance as a new nitrogen source secondly ad is highly dynamic in terms of the magnitudes of dissolved inorganic nitrogen din and dissolved organic nitro

anti cyclonic eddies northwest of luzon in summer fall observed by satellite altimeters anti cyclonic eddies northwest of luzon of the philippines in summer fall are identified in the merged data products of satellite altimeters of topex poseidon jason 1 and european research satellites the generation and propagation of the anti cyclonic eddies which are confirmed by satellite ocean color data are found to be a seasonal phenomenon that is phase locked to the onset of the southwesterly monsoon and the relaxation of the cyclonic wind curl in the northeastern south china sea the eddies originate from northwest of luzon in summer move across the northeastern south china sea to reach the china continental slope in fall and propagate southwestward along the continental slope in fall winter inducing shelfbreak current variations in the western south china sea in fall winter the anti cyclonic eddy discovered by li et al 1998 in the northern south china sea is found to originate from northwest of luzon and carry primarily the south china sea waters it does not appear to be an eddy shed from the kuroshio in the luzon strait area as alluded by li et al 1998 and others

pull aparts shear fractures and pressure solution vein arrays are often composed of pull aparts which are linked by shear fractures good examples of which occur in the lower jurassic limestones of somerset southwestern england such pull apart arrays have displacement distance characteristics which are similar to fault zones with maximum displacement indicated by the largest pull apart widths near the centre of the array and with displacement decreasing towards the tips pull apart arrays usually die out into enechelon or pinnate veins evidence for pressure solution along the shear fractures which connect pull aparts include their dark and braided nature their obliquity to the displacement direction the high dihedral angles often 90 between conjugate shear fractures and the dissolution of earlier structures a range of geometries occurs with varying relative amounts of veins and pressure solution being related to varying amounts of transtension or transpression there is a general trend for an increase in the angle between vein segments and the shear fractures as contraction increases there is therefore a trend for increased pressure solution on the shear fractures in more contractional arrays the concentration of insoluble material along shear fractures has important implications for the mechanics and sealing of faults

the importance of small scale faulting in regional extension a recurring observation in many studies of extensional basins has been that the amount of extension visible on normal faults for example on seismic reflection profiles is significantly less than the amount of extension indicated by crustal thickness and thermal subsidence1 5 one mechanism suggested to account for this discrepancy is small scale faulting with offsets too small to be resolved seismically6 7 but earthquake studies8 10 indicate that small faults are responsible for only a small fraction of the total seismic moment in an active area scholz and cowie11 have recently attempted to extend this approach to the total strain at the end of a finite deformation interval by combining scaling laws describing the distributions of fault lengths and displacements here we present fault displacement data that directly conflict with scholz and cowie s conclusions and imply that up to 40 of the extension may be missed by summing fault offsets on basin profiles the fault population at the end of a long deformation interval may differ substantially from that responsible for the earthquake population at any one time

bathymetric mapping of the coastal and offshore geology and structure of the jurassic coast weymouth bay uk four hundred square kilometres of 1 m binned full coverage swath bathymetry data integrated with similar resolution onshore topography have been used to generate a seamless onshore to offshore bedrock map covering an extensive area adjacent to the jurassic coast world heritage site analysis of these data provides new insights into the structural development of the purbeck monocline cenozoic inversion structure in particular variations in the expression of strain between the hanging wall block and the fault inversion zone the footwall to the basin bounding faults compartmentalized deformation and uplift and acted as a buttress to compression the data also show a limited thickness changes within the major lithostratigraphical divisions and a notable absence of basin related extensional faulting in the offshore area that is in marked contrast to the more extensively studied onshore region this indicates that prior to inversion the basin evolved by intermittent activity on a few major extensional faults this improved understanding of the development of the basin and inversion structures results from our ability to integrate and quantitatively manipulate these high resolution and spatially extensive offshore and onshore datasets

the structure and evolution of the wessex basin southern england an example of inversion tectonics abstract the wessex basin of southern england consists of four main sub basins each sub basin is thought to be fundamentally controlled by the normal reactivation of hercynian basement thrust and wrench or transfer faults post hercynian polyphase reactivation of both east west thrust and northwest southeast transfer faults tended to compartmentalise the basement thereby leading to the initiation of discrete permian cretaceous depocentres while rifting was confined to the western portions of the area during the permo triassic easterly migration in the mesozoic allowed the initiation of the weald and channel basins the sub basins represent therefore simple sinistral pull apart basins opening along northwest southeast faults this same fault direction is postulated to have also played a major role in controlling and or modifying the development of european basins in general major pre aptian uplift and erosion is largely attributed to the thermal effects and hence the isostatic uplift of the basin associated with continental rifting of the bay of biscay and the north atlantic margins major inversion and hence basin destruction began in the late cretaceous early tertiary with the uplift of the channel weald and vale of pewsey basins and culminated in the oligocene miocene synchronous with the helvetic phase of alpine deformation wessex basin inversion was facilitated by the thrust reactivation of variscan faults above an intracrustal detachment surface the same surface which allowed upper crustal extension and hence basin initiation in the permo triassic the structural development of the wessex basin both during extension basin formation phase and compression inversion phase was ultimately controlled by the plate motion of africa relative to europe such plate motions successfully predict the observed nw se sinistral motion from the stephanian to the aptian e w sinistral motion during the aptian cenomanian and largely nw se dextral motion from the cenomanian to the present day

interannual variability of south china sea winter circulation response to luzon strait transport and el nino wind the el nino wind and luzon strait transport are important factors modulating the interannual variability of the southern and northern south china sea scs winter circulation respectively the joint effect of el nino wind and westward luzon strait transport drives a dipolar gyre with an anticyclonic cyclonic circulation anomaly in the southern northern scs which enhances the cross basin current that connects the scs western boundary current with the eastern boundary of the scs around the mindoro strait and then effectively modulates the interannual variability of mindoro strait transport an extreme el nino and large luzon strait intrusion occurred in winter 2015 16 and mooring observations and remote sensing data confirmed the presence of an intense dipolar gyre this resulted in an extreme eastward cross basin current and outward scs mindoro strait transport anomaly in 2015 16

aspects of basin inversion in southern britain the wessex basin of southern england a permian to cretaceous extensional basin can be structurally divided into a set of constituent asymmetrical graben bounded by major e w trending zones of en echelon syn depositional normal faults the graben were inverted in late cretaceous and tertiary times by compressive stresses oriented roughly north south inversion structures fall into two related categories regional upwarps overlie earlier graben depocentres and were formed by bulk shortening of the graben fill superimposed upon and geographically delimiting the regional upwarps are roughly east west trending linear zones of en echelon inversion structures these coincide with the earlier graben bounding faults and typically have the form of monoclinal or periclinal flexures each underlain by a partially reversed normal fault the linear reverse fault monocline inversion structures were a relatively inefficient method of basin shortening because upper crustal faults in the region steepen upward markedly reversal of these faults under compression resulted in a shortening discrepancy at shallow depths locally particularly in south dorset this was overcome by bucklefolding and low angle reverse faulting which increased the amount of shortening attainable across the linear inversion structures elsewhere however the shortening discrepancy was accommodated by bulk shortening and regional upwarp of the graben sedimentary fill this occurred preferentially in those graben containing young poorly lithified and therefore weak sediments thus the early cretaceous depocentres of the weald and channel basins were strongly upwarped with axial uplifts of over 1000 m conversely graben having older more lithified sequences suffered little regional upwarp shortening primarily by fault reversal along the linear inversion structures the amount of crustal shortening which accompanied inversion was considerably less than the earlier crustal extension

intraseasonal variability of cross slope flow in the northern south china sea abstractcross slope flow plays an important role in the exchange of material heat and momentum between the continental shelf and the open sea in the northern south china sea scs long period ob

the use of high resolution seismic reflection profiles for fault analysis in the near shore environment weymouth bay dorset england united kingdom high resolution seismic reflection profiles using a chirp source image a north south extensional fault set which cuts rocks of upper jurassic age cropping out on the seafloor of weymouth bay dorset england united kingdom the same fault set cuts rocks of similar age along the adjacent coast and field mapping can be compared directly with the chirp profiles survey lines were shot perpendicular to the fault strike to produce dip sections from which displacements could be measured one hundred and fifty three faults were picked on a 15 km line yielding a fault density of 10 km 1 similar to that measured in the coastal section chirp resolved fault displacements as small as 0 5 m and a maximum fault displacement of 221 m could be inferred from the data distribution analysis of offshore fault data indicated that fault displacement is power law with a well constrained exponent of 0 9 this value is consistent with the power law exponent estimate for fault displacement over the scale range 2 8 m onshore thus chirp near shore seismic reflection profiles can infill a data gap for fault size frequency relationships that commonly occurs when combining data from outcrops cores and conventional seismic reflection profiles

progressive localisation of strain during the evolution of a normal fault population abstract the evolution of a syn sedimentary normal fault population has been established from the analysis of a high quality 3d seismic reflection survey from the timor sea offshore nw australia growth of the fault population which initiated ca 6 ma ago occurred in three distinct but temporally overlapping stages the initial stage of fault population evolution was characterised by rapid growth of fault length in the first 1 2 ma of extension displacement rates of individual faults were established during this stage and were constant throughout subsequent fault growth the second stage involved amplification of fault displacements on existing fault traces with minimal fault propagation during the third stage shortening of the traces of active faults and high mortality rates for small faults resulted in a net decrease in fault trace length on successively younger horizons this stage was accompanied by a declining extension rate fault throw populations have constant slopes on each syn faulting horizon however an up sequence shallowing of the slope of length and geometric moment populations demonstrates a progressive concentration of strain onto fewer and larger faults through time if extension were to continue beyond the present value of 4 5 this strain localisation might culminate in the formation of a single active through going fault

the distribution of faults and fractures and their importance in accommodating extensional strain at kimmeridge bay dorset uk the spatial distribution of extensional strain in interbedded mudstones and carbonates from around kimmeridge bay in southern england is examined using a variety of line samples normal faults and tensile fractures veins from the same deformation event show displacements ranging over 6 orders of magnitude the relative contribution of these structures to the overall extension varies with large faults 10 m heave accommodating about 65 smaller faults 1 10 m heave about 25 and veins less than 10 of the overall extension the heterogeneity of fracture density and strain can be quantified from cumulative plots by applying a non parametric method based on kuiper s test both the degree and statistical significance of strain heterogeneity can be determined and are shown to be scale dependent thin veins accommodate a fairly constant background strain across the region whilst thick veins and small faults take up localized higher strains in damage zones around larger faults fault strain is relatively homogenously distributed across the region the faults and veins do not share the same scaling relationship thus this study shows that it is not possible to simply extrapolate fracture frequencies and strain from fault scale to vein scale and that the heterogeneity of extensional strain is scale dependent

scaling of fault displacements from the badajoz cordoba shear zone sw spain faulting occurs over a large range of scale parts of which are sampled by various techniques e g microscopy outcrop measurement mapping seismic reflection and other forms of remote sensing use of a single technique to measure displacement or strain will not sample faults at all scales and hence will give a biased estimate in order to assess this bias a knowledge of the distribution over all scales is needed many samples of fault displacement appear to follow a power law distribution with departures which can be attributed to sampling effects the number of faults with a displacement u is given by n u cu d the power law distribution of displacement is consistent with similar distributions of other fault parameters and earthquake magnitudes when sampling along a line e g a bedding trace on a map or section a self similar fault population would have d 1 whereas self affine geometries yield d 1 displacement and extension are dominated by small faults when d 1 and by large faults when d 1 when sampling over areas or volumes these critical values are 2 and 3 respectively a set of strike slip faults from the badajoz cordoba shear zone spain were sampled at two different scales using 1 50000 maps and outcrop measurements displacement ranges over 6 orders of magnitude these and other fault populations typically have d ranging from 0 6 to 1 5 the power law relationship may be integrated to yield estimates of the displacement or extension for faults which lie beyond the resolution of the sampling system for example a knowledge of d allows the extension measured on a map or seismic section to be corrected for faults whose displacement is below the resolution of the survey based on an overall estimate of d 0 9 for the badajoz cordoba data only some 40 of the extension would be recorded by map scale faults a corrected extension of 41 along the shear zone is estimated which if typical for the entire 300 km zone represents some 87 km of along strike extension thus work suggests that significant displacement occurs on faults which are too small to be interpreted from conventional seismic profiles and geological maps

a census of eddy activities in the south china sea during 1993 2007 1 numerous mesoscale eddies occur each year in the south china sea scs but their statistical characteristics are still not well documented a pacific basin wide three dimensional physical biogeochemical model has been developed and the result in the scs subdomain is used to quantify the eddy activities during the period of 1993 2007 the modeled results are compared with a merged and gridded satellite product of sea level anomaly by using the same eddy identification and tracking method on average there are about 32 9 2 4 eddies predicted by the model and 32 8 3 4 eddies observed by satellite each year and about 52 of them are cyclonic eddies the radius of these eddies ranges from about 46 5 to 223 5 km with a mean value of 87 4 km more than 70 of the eddies have a radius smaller than 100 km the mean area covered by these eddies each year is around 160 170 km2 equivalent to 9 8 of the scs area with water depths greater than 1000 m linear relationships are found between eddy lifetime and eddy magnitude and between eddy vertical extent and eddy magnitude showing that strong eddies usually last longer and penetrate deeper than weak ones interannual variations in eddy numbers and the total eddy occupied area indicate that eddy activities in the scs do not directly correspond to the el nino southern oscillation events the wind stress curls are thought to be an important but not the only mechanism of eddy genesis in the scs

oceanic eddy formation and propagation southwest of taiwan 1 oceanic eddies are active and energetic southwest of taiwan the formation and propagation of eddies in this area were investigated using 17 year satellite altimeter data cyclonic eddies ces and anticyclonic eddies aces often coexisted but there were more ces than aces generated during the period from october 1992 to october 2009 aces were stronger and in general lived longer than ces aces occurred more often in winter than in other seasons while ces were more frequent in summer compared with the direct local wind forcing the kuroshio path variability appears to be a dominant factor for eddy formation in this area a conceptual model of an eddy kuroshio interaction is proposed in summer there exists an outflow northwest of luzon island and the kuroshio likely leaps across the luzon strait to the north of the outflow and left of the kuroshio axis ces are often formed which in turn induce aces to the west of ces in winter under the influence of northeasterly monsoon the kuroshio current loop kcl appears southwest of taiwan more frequently than in other seasons and aces are frequently shed from the kcl most of the aces propagate westward and as a result ces are often spun up to the east of the aces the surface south china sea outflow in summer and the kcl in winter are however likely related to the monsoons therefore the indirect effects of monsoon winds are also evident in the seasonal variations of eddy occurrence

amount of extension on small faults an example from the viking graben extension estimates based on palinspastic restoration of only the largest faults in a deformed terrane may be significantly deficient due to neglect of small faults i e unsampled faults most of which have smaller displacements than do sampled faults small faults individually account for little extension but there may be large numbers of them the cumulative extension on small faults can be calculated from the fractal size distributions of fault displacements independent extension estimates support the inference from fault population statistics that small faults account for significant amounts of extension for example restorations of mesozoic faults interpreted from seismic reflection profiles across the viking graben in the north sea yield extension estimates that are only 40 75 of independent estimates the fractal size distribution of fault displacements in the viking graben is consistent with the hypothesis that the remaining 25 60 of extension resulted from displacements on small faults

mesoscale eddies cases study at xisha waters in the south china sea in 2009 2010 analyzing the observed currents at xisha 110 3899 degrees e 17 1038 degrees n during may 2009 to may 2010 it is found that the kinetic energy has significant mesoscale variability and each peak responds to large positive negative ocean surface current curl caused by mesoscale eddies compared the kinetic energy with the wind stress work and the pressure work it is also found that the barotropic pressure work which is mainly contributed by the sea surface height ssh corresponding to the mesoscale eddies behaves like the kinetic energy the contribution of the mesoscale eddies to the kinetic energy can be up to 90 sometimes and reach deep level every time using the satellite altimeter data the paths of mesoscale eddies contributing to the kinetic energy variability are traced back in the winter half of the year the mesoscale eddies propagating along the northern south china sea shelf or across the basin from the west of the philippines toward xisha arrive at xisha influencing the kinetic energy in the summer half of the year the mesoscale eddies are mainly from the south which were shed from the vietnam coast current and the cause for eddy shedding may be related to the relaxation of the ekman transport anomalies

quantifying opening mode fracture spatial organization in horizontal wellbore image logs core and outcrop application to upper cretaceous frontier formation tight gas sandstones usa abstract the upper cretaceous frontier formation is a naturally fractured gas producing sandstone in wyoming regionally random and statistically more clustered than random patterns exist in the same upper to lower shoreface depositional facies east west and north south striking regional fractures sampled using image logs and cores from three horizontal wells exhibit clustered patterns whereas data collected from east west striking fractures in outcrop have patterns that are indistinguishable from random image log data analyzed with the correlation count method shows clusters 35 m wide and spaced 50 to 90 m apart as well as clusters up to 12 m wide with periodic inter cluster spacings a hierarchy of cluster sizes exists organization within clusters is likely fractal these rocks have markedly different structural and burial histories so regional differences in degree of clustering are unsurprising clustered patterns correspond to fractures having core quartz deposition contemporaneous with fracture opening circumstances that some models suggest might affect spacing patterns by interfering with fracture growth our results show that quantifying and identifying patterns as statistically more or less clustered than random delineates differences in fracture patterns that are not otherwise apparent but that may influence gas and water production and therefore may be economically important

eddy heat and salt transports in the south china sea and their seasonal modulations this study describes characteristics of eddy turbulent heat and salt transports in the basin scale circulation as well as in the embedded mesoscale eddy found in the south china sea scs we first showed the features of turbulent heat and salt transports in mesoscale eddies using sea level anomaly sla data in situ hydrographic data and 375 argo profiles we found that the transports were horizontally variable due to asymmetric distributions of temperature and salinity anomalies and that they were vertically correlated with the thermocline and halocline depths in the eddies an existing barrier layer caused the halocline and eddy salt transport to be relatively shallow we then analyzed the transports in the basin scale circulation using an eddy diffusivity method and the sea surface height data the argo profiles and the climatological hydrographic data we found that relatively large poleward eddy heat transports occurred to the east of vietnam eov in summer and to the west of the luzon islands wol in winter while a large equatorward heat transport was located to the west of the luzon strait wls in winter the eddy salt transports were mostly similar to the heat transports but in the equatorward direction due to the fact that the mean salinity in the upper layer in the scs tended to decrease toward the equator using a 21 2 layer reduced gravity model we conducted a baroclinic instability study and showed that the baroclinic instability was critical to the seasonal variation of eddy kinetic energy eke and thus the eddy transports eov wls and wol were regions with strong baroclinic instability and thus with intensified eddy transports in the scs the combined effects of vertical velocity shear latitude and stratification determined the intensity of the baroclinic instability which intensified the eddy transports eov during summer and wls and wol during winter

winter eddy genesis in the eastern south china sea due to orographic wind jets abstract generation of mesoscale eddies in the eastern south china sea scs in winters during august 1999 to july 2002 is studied with a reduced gravity model it is found that the orographic wind jets associated with the northeast winter monsoon and the gaps in the mountainous island chain along the eastern boundary of the scs can spin up cyclonic and anticyclonic eddies over the scs results suggest that direct wind forcing could be an important generation mechanism for the rich eddy activity in the scs and that to simulate this mechanism the resolution of the wind forcing has to be high enough to resolve the local wind jets induced by orographic effects

localized vs distributed deformation associated with the linkage history of an active normal fault whakatane graben new zealand abstract the deformation associated with an active normal fault is investigated at a high temporal resolution c 10 4 yr the rangitaiki fault whakatane graben new zealand and its adjacent faults accommodated an overall extension of 0 83 oriented at n324 e over the past 17 kyr this is consistent along strike but the pattern of faulting that accommodates this strain defines two different spatial domains to the sw one domain is characterized by a few large faults with 80 of strain localized onto geometrically and kinematically linked segments of the main fault this produces marked heterogeneity in the spatial distribution of strain across the graben in contrast to the ne a domain of distributed faulting is characterized by numerous small faults contributing to the overall deformation with only 35 of strain localized onto the rangitaiki fault the transition from distributed to localized deformation is attributed to an increase in linkage maturity of the rangitaiki fault progressive strain localization has been ongoing within the network over the last 17 kyr with localization of fault activity increasing by 12 indicating this process occurs over kyr time periods that only reflect a few earthquake events

generation and life cycle of the dipole in the south china sea summer circulation 1 the south china sea scs summer circulation often has a dipole structure associated with an eastward jet appearing off central vietnam the dipole has an anticyclonic eddy ae south of the jet and a cyclonic eddy ce north of it the life cycle of the dipole structure is analyzed using satellite altimetry data and a reduced gravity model on average the dipole structure begins in june peaks in strength in august or september and disappears in october the dipole evolution lags behind the basin scale wind by about 40 days and 40 days are exactly what it takes for baroclinic planetary waves to cross the southern scs our results show that the vorticity transports from the nonlinear effect of the western boundary currents are crucial for the generation of the dipole structure in addition the strength and direction of the offshore wind jet also play a significant role in determining the magnitudes and the core positions of the two concomitant eddies

integrated stratigraphy of the kimmeridge clay formation upper jurassic based on exposures and boreholes in south dorset uk for the purposes of a high resolution multi disciplinary study of the upper jurassic kimmeridge clay formation two boreholes were drilled at swanworth quarry and one at metherhills south dorset uk together the cores represent the first complete section through the entire formation close to the type section we present graphic logs that record the stratigraphy of the cores and outline the complementary geophysical and analytical data sets gamma ray magnetic sus ceptibility total organic carbon carbonate 13 c org of particular note are the new borehole data from the lowermost part of the formation which does not crop out in the type area detailed logs are available for download from the kimmeridge drilling project web site at http kimmeridge earth ox ac uk of further interest is a mid eudoxus zone positive shift in the 13c org record a feature that is also registered in tethyan carbonate successions suggesting that it is a regional event and may therefore be useful for correlation the lithostratigraphy of the cores has been precisely correlated with the nearby cliff section which has also been examined and re described magnetic susceptibility and spectral gamma ray measurements were made at a regular spacing through the succession and facili tate core to exposure correlation the strata of the exposure and core have been subdivided into four main mudrock lithological types a medium dark dark grey marl b medium dark dark grey greenish black shale c dark grey olive black laminated shale d greyish black brownish black mudstone the sections also contain subordinate amounts of siltstone limestone and dolostone comparison of the type section with the cores reveals slight lithological variation and notable thick ness differences between the coeval strata the proximity of the boreholes and different parts of the type section to the purbeck isle of wight disturbance is proposed as a likely control on the thickness changes

weakest winter south china sea western boundary current caused by the 2015 2016 el nino event during the winter of 2015 2016 the strongest el nino event of the 21st century occurred at the same time volume transport vt time series of the south china sea western boundary current scswbc exhibited a minimum value of 3 7 sv 1 sv 1 106 m3 s 1 toward the southwest indicating the weakest strength ever recorded in boreal winter from november to february the south china sea scs cyclonic gyre inferred from the satellite derived surface absolute geostrophic current was significantly reduced it was considered that the weakened wind stress curl negative anomaly over the scs resulting from an anticyclone over the philippine sea played an essential role the anticyclone arose from a rossby wave response to a negative sea surface temperature anomaly in the northwest pacific this idea is further supported by composite analysis which shows that during el nino la nina winter negative positive wind stress curl anomalies prevail in the philippines sea and the scs thus the wind stress curl over the scs is reduced strengthened leading to a weaker stronger scs cyclonic gyre and scswbc the mean vt of scswbc is 4 7 sv 5 6 sv which is smaller larger than 5 2 sv in normal years this study provides robust observational evidence from long term in situ volume transport monitoring that el nino can have a significant impact on the scswbc through an atmosphere bridged teleconnection this article is protected by copyright all rights reserved

spatial structure and temporal variability of the zonal flow in the luzon strait one year long full depth velocity measurements were used to examine the spatial structure and temporal variability of the zonal flow in the luzon strait lszf the observation revealed a renewed mean flow structure in the upper 2000 m layers the lszf was mostly westward in the intermediate layer 500 2000 m it was dominated by an eastward flow in the south but a westward flow in the north the volume transport across the observed section between 19 8 n and 21 2 n exhibited strong seasonal and intraseasonal variability on the seasonal time scale the upper layer transport showed a clear annual cycle strongest in january and weakest in june the intermediate layer transport also showed a semiannual cycle attaining its peaks troughs in january and june april and october on the intraseasonal time scale both the upper layer and intermediate layer transports showed significant energy peaks at about 60 and 10 30 days further analysis indicated that the 60 day variability might be attributed to the impinging mesoscale eddies from the pacific while the 10 30 day variability appeared to obtain its energy from local intraseasonal wind forcing and baroclinic instability of the background current the 10 100 day upper layer and intermediate layer transport variabilities were highly anticorrelated suggesting a baroclinic nature of the intraseasonal variabilities of the lszf

anticyclonic eddy sheddings from kuroshio loop and the accompanying cyclonic eddy in the northeastern south china sea abstractsheddings of kuroshio loop current klc eddies in the northeastern south china sea scs are investigated using mooring arrays multiple satellite data and data assimilative hycom products based on altimeter sea surface heights between 1992 and 2014 a total of 19 prominent klc eddy shedding klces events were identified among which four events were confirmed by the concurrent moored and satellite observations compared to the leaping behavior of kuroshio klces is a relatively short duration phenomenon that primarily occurs in boreal autumn and winter the klc and its shedding anticyclonic eddy ae trap a large amount of pacific water with high temperature salinity and low chlorophyll concentration in the upper layer the corresponding annual mean transport caused by klces reaches 0 24 0 38 sv 1 sv 106 m3 s 1 accounting for 6 8 10 8 of the upper layer luzon strait transport altimeter based statistics show that among 90 of the historical klces events a cyclonic eddy ce is immedi

an analysis of the current deflection around dongsha islands in the northern south china sea based on the in situ data and adcp observation in fall it is found that a northeastward current at inter middle level flows on the northern south china sea nscs continental shelf this current flows almost along the isobaths and it deflects from the isobaths veering toward deep water when flowing over the dongsha islands geographic currents derived from the climatologic hydrography data woa01 and absolute dynamic topography adt data confirm the deflection of the northeastward current on nscs continent a fine resolution regional ocean model which can well reproduce the large scale circulation in the nscs is used to analyze the dynamic about the deflection the vorticity term balances shows that jebar joint effect of baroclinicity and relief drives the water column to depart from the isobaths to the east of the dongsha islands the isopycnal is almost orthogonal to the isobaths the joint effect of the topographic and the baroclinic effect supplies negative vorticity and drives the water column to deflect from the isobaths and veer to deeper water momentum analysis along the stream line shows that when the sea water flows around the dongsha islands the pressure gradient along the isobath pushes the sea water to accelerate and then the coriolis force orthogonal to the isobath increases and overcomes the corresponding pressure gradient which drives the water deflected from the isobath toward the deep sea citation wang d q wang w zhou s cai l li and b hong 2013 an analysis of the current deflection around dongsha islands in the northern south china sea j geophys res oceans 118 490 501 doi 10 1029 2012jc008429

organic geochemical study of the upper kimmeridge clay of the dorset type area abstract results are presented from an organic geochemical investigation of a suite of rock samples taken from the upper kimmeridge clay near kimmeridge dorset all samples contain immature organic matter of marine origin although one horizon the whitestone band contains an additional secondary input of partially biodegraded mature hydrocarbons due to an oil seepage of unknown origin with the exception of increased relative abundances of 4 methylsteroidal hydrocarbons in the more organic rich samples the immature molecular distributions are very similar suggesting a consistent source of organic matter the results are in agreement with the palaeoenvironmental model proposed by tyson et al 1979 for the deposition of the kimmeridge clay where the different lithologies are controlled by a fluctuating oxic anoxic boundary with only the organic poor mudstones being deposited in relatively oxygenated waters

observation of luzon strait transport using recently collected current and hydrographic data we provide a high resolution picture of the subinertial flow and estimate the volume transport through the luzon strait the distribution of the subinertial flow shows a strong westward flow around 100 m in the northern part of the luzon strait while the eastward flow is confined to the deeper layers mostly at depths around 1000 m the total volume transport is estimated to be 6 3 sv during the period of observations from october 4 to 16 2005 the observations also confirm that the luzon strait transport has a sandwiched vertical structure the net westward volume transport in the deep 1500 m layer of the luzon strait reaches 2 sv

decadal variation and trends in subsurface salinity from 1960 to 2012 in the northern south china sea observations suggest that subsurface waters in the northern south china sea nscs exhibited substantial low frequency variability with a striking decadal change in the southern limit of the 34 6 psu isohaline long term freshening of the subsurface waters started in 1960 was followed by salinification from 1975 and freshening occurred again from 1993 to 2012 the linear trends were 0 0076 0 0100 and 0 0078 psu yr respectively an analysis of the subsurface salinity budget reveals that the main underlying contributors to subsurface salinity are horizontal advection and vertical entrainment in particular advection driven by the luzon strait transport and vertical entrainment from the mixed layer are the key factors controlling variations on subsurface salinity diagnosis of the salinity budget further suggests that entrainment from the mixed layer played a more important role in the freshening periods than in the salinifying period

the thermal and mechanical development of the wessex basin southern england summary the wessex basin of southern england is an e w trending late palaeozoic to tertiary extensional basin formed on early palaeozoic variscan crust extension occurred over a protracted period from late carboniferous to cretaceous times resulting in the evolution of four main depocentres or sub basins the channel basin winterborne kingston trough vale of pewsey and weald basins each sub basin was controlled fundamentally by the normal reactivation of basement thrust faults and wrench or transfer faults the basement faults represent primary structures associated with the fold and thrust terrain of the devonian carboniferous variscan orogeny subsequent but synchronous reactivation of both thrust and transfer faults tended to compartmentalize the basement leading to discrete depocentres and the production of general rhomboidal shaped sub basins characteristic of pull apart basins in strike slip terrains to investigate the thermo mechanical properties of the lithosphere during basin formation 50 boreholes within the wessex basin were back stripped to isolate the driving tectonic subsidence responsible for basin formation the resultant driving subsidence is characterized by a gentle sometimes negative exponential form with superimposed rapid discrete subsidence events as the geological development of the wessex basin was characterized by polyphase extension and the utilization of crustal detachments the lithospheric model used to determine crustal extension above the detachment and stretching below the detachment included the effects of depth dependent stretching and finite re rifting from the back stripping analysis the basin wide averaged upper crustal extension and lower crustal sub crustal lithospheric stretching were 11 and 5 respectively the distribution of is strongly influenced by the location of growth faults and hence basement thrust fault reactivation suggesting that is reflecting the brittle failure and collapse of hanging wall blocks repeated slip and block collapse resulted in the polyphase extension responsible for renewed basin subsidence in contrast is uniformly distributed across the basin suggestive of a ductile failure of the lower crust and responsible for the low magnitude thermal subsidence strain compatibility between the upper crust and lower crust sub crustal lithosphere is maintained partly within the basin 5 and partly external to the basin as the variscan basal thrust was the fundamental relay in the sense of wernicke responsible for the wessex basin formation we postulate that strain balancing induced a cumulative essentially thermal isostatic uplift of 60 m under the northern margin of the armorican massif

mesoscale dongsha cyclonic eddy in the northern south china sea by drifter and satellite observations 1 near the center of the northern south china sea nscs the dongsha atoll is situated on the continental slope that runs from taiwan to hainan a mesoscale cyclonic eddy south or southwest of dongsha seems to appear annually and has been identified as the dongsha cyclonic eddy dce historical drifter 1988 2005 and satellite altimeter 2000 2005 data were adopted to study the variations to and characteristics of the dce some typical features were derived such as mean tangential speed of 20 cm s moving speed of 8 km d i e 9 cm s eddy size of 22 103 km2 center sea surface lowering height difference dif of 6 cm and angular velocity of 9 d mean tangential speeds of 12 16 cm s in late spring and summer are slower than those of 16 31 cm s in winter and early spring moving speeds are of the order of the rossby wave at nscs latitudes variations in the time series of eddy size and dif are generally similar and show a positive linear relation between them the dce starts near dongsha and moves southwestward along the continental slope at a depth of 1000 2000 m the eddy peaks with maximum eddy size and dif when reaching 114 e and then diminishes south of hainan because of trapping of the underwater bay formed by the continental slope the dce typically exists 1 2 times per year and lasts 1 3 months roughly 90 of observed dces formed in winter or spring a unique dce was identified in the summer of 2000 and lasted for over 4 months its birth was associated with typhoon kai tak the positive linear relationship between eddy size and dif in this case was unique before reaching 114 e and then returned to the typical relationship of other dces the dif of this unique dce attained the highest of 24 cm right at the climax longitude according to avhhr and seawifs images such a dce is associated with a core of which sea surface temperature is 2 c lower and chlorophyll a concentration is 0 1 mg m3 higher than those of surrounding seas migration of the dce may be linked to tuna fish farms in the nscs

microfracture spacing distributions and the evolution of fracture patterns in sandstones abstract natural fracture patterns in sandstone were sampled using scanning electron microscope based cathodoluminescence sem cl imaging all fractures are opening mode and are fully or partially sealed by quartz cement most sampled fractures are too small to be height restricted by sedimentary layers at very low strains 100 datasets show spacings that are best fit by log normal size distributions compared to exponential power law or normal distributions the clustering of fractures suggests that the locations of natural factures are not determined by a random process to investigate natural fracture localization we reconstructed the opening history of a cluster of fractures within the huizachal group in northeastern mexico using fluid inclusions from synkinematic cements and thermal history constraints the largest fracture which is the only fracture in the cluster visible to the naked eye among 101 present opened relatively late in the sequence this result suggests that the growth of sets of fractures is a self organized process in which small initially isolated fractures grow and progressively interact with preferential growth of a subset of fractures developing at the expense of growth of the rest size dependent sealing of fractures within sets suggests that synkinematic cementation may contribute to fracture clustering

modeling south china sea circulation response to seasonal forcing regimes 1 a three dimensional ocean model has been utilized to study circulation and its seasonal variation in the south china sea scs in response to the forcing of the asian monsoon and the kuroshio intrusion the scs ocean model has a resolution of approximately 10 km horizontal spacing and 30 vertical levels with a realistic bottom topography the model is forced with time dependent wind stress and heat flux from national center for environmental prediction reanalysis data as well as with lateral fluxes from a pacific ocean model of 40 km horizontal resolution this study reports on the analysis of the mean seasonal circulation and dynamic processes in response to monsoonal wind stress the kuroshio intrusion and other intrinsic forcing processes it is found that the seasonal circulation in the scs is mainly driven by the monsoonal wind stress and greatly influenced by the inflow from the kuroshio intrusion strong currents along the continental margin of the scs form mean basin wide cyclonic and anticyclonic circulations in the winter and summer respectively multiscale eddies are embedded in the general circulation across the basin while mainstream of the kuroshio passes through the luzon strait without intruding into the scs partial intrusion occurs in the upper 200 m near the shelf margin southwest of taiwan at times when winter dynamic conditions prevail in the north scs the intrusion of the kuroshio into the scs also occurs at depths in all seasons mainly along the continental slope the coastal current separation to the east off southern vietnam and the associated eddy formations characterize the circulation in the south scs the simulated results compare well with the corresponding observed fields dynamical processes involved in the forced flow fields are investigated by examination of the momentum balances the analyses reveal that the circulation in the scs is generally dominated by the geostrophic currents north of the luzon strait positive nonlinearity in the zonal direction is locally intensified which leads to the formation of centripetal acceleration for the mainstream of the kuroshio to turn eastward the kuroshio intrusion at depths is governed by the ageostrophic flows and highly associated with the net westward pressure gradient force coastal jet separation to the east off vietnam is mainly associated with the local wind stress field and with the shelf topography in the summer and winter respectively sensitivity study reveals that the weakening of the kuroshio markedly enhances kuroshio s intrusion and forms an anticyclonic eddy west of the luzon strait

energetic topographic rossby waves in the northern south china sea abstracttopographic rossby waves trws are reported to make a significant contribution to the deep ocean current variability on the northern south china sea nscs continental slope trws with pe

analysis of a strike slip fault network using high resolution multibeam bathymetry offshore nw devon u k abstract imaging of the sea floor offshore from hartland point north devon u k using high resolution multibeam bathymetry reveals a strike slip fault network this consists of ne trending left lateral faults and nw trending right lateral faults that cut folded and steeply dipping strata 60 faults were accurately mapped using the multibeam imagery and lateral separations of marker beds measured along fault traces these data are used to examine the spatial arrangement fault displacement and strain distribution within the network at different displacement cut offs at high displacement cut offs the fault network is dominated by a few long isolated right lateral fault segments that bound fault blocks but at lower displacement cut offs shorter left lateral and right lateral fault segments make up fault tips and infill fault blocks the majority 70 of fault trace length is taken up by small fault segments that have 10 m displacement the topology and relative connectivity of the network is analysed in terms of a system of fault branches between tips i nodes or intersections x or y nodes the relative proportions of which reflect the connectivity of the network although the kinematic behaviour of the fault network is controlled by large fault segments connectivity is very dependent on the small fault segments a comparison with a similar nearby strike slip fault network at westward ho north devon shows many similarities and indicates that fault networks are better connected with increasing strain and that the network becomes better connected when strain is localized within damage zones rather than on individual faults

scaling relationships of joint and vein arrays from the burren co clare ireland abstract we present a study of the systematics of veins and joints in carboniferous limestones of the burren ireland scaling relationships were established for fracture arrays mapped from low elevation aerial photographs that image fractures on numerous limestone pavements for areas up to ca 1 km2 the veins and joints occur in the same sequence but have contrasting scaling properties the veins strike north south and cut many beds to form vertically persistent non stratabound arrays they are strongly clustered and have scale invariant geometric properties vein geometries suggest they grew sub critically under relatively high differential stresses during north south directed variscan compression the joints form stratabound arrays with regular spacings that scale with bed thickness they show greater strike variation than the veins and have lognormal length distributions the joints formed during uplift under low differential stress conditions the contrasting scaling properties of the joints and veins are attributed to different overburden stresses at the time of formation the veins formed at greater depths than the joints in conditions that favoured fracture propagation across mechanical discontinuities resulting in the development of non stratabound scaling properties

summer upwelling in the south china sea and its role in regional climate variations seasonal and interannual variations of summer upwelling off the south vietnam coast and the offshore spread of cold water are investigated using a suite of new satellite measurements in summer as the southwesterly winds impinge on annam cordillera a north south running mountain range on the east coast of indochina a strong wind jet occurs at its southern tip offshore east of saigon resulting in strong wind curls that are important for ocean upwelling off the coast in july and august an anticyclonic ocean eddy develops to the southeast advecting the cold coastal water offshore into the open south china sea scs the center of this cold filament is located consistently north of the wind speed maximum indicating that open ocean upwelling helps to cool the ocean surface corroborating evidence for the cold filament is found in ocean color observations that reveal a collocated tongue of high chlorophyll concentration the development of this cold filament disrupts the summer warming of the scs and causes a pronounced semiannual cycle in sst moreover the cold filament is an important player in interannual variability in the summer scs in 1998 the cold filament and mid summer cooling never took place giving rise to a strong basin wide surface warming interannual sst variance has a local maximum over the climatological cold filament and is much greater than the variance over the adjacent indian and western pacific oceans a cold filament index is constructed which displays significant lagged correlation with sst in the eastern equatorial pacific and indian oceans indicative of a teleconnection from el nino

interdecadal variability of the eastward current in the south china sea associated with the summer asian monsoon abstract based on the simple ocean data assimilation soda dataset and three types of sverdrup streamfunction an interdecadal variability of the eastward current in the middle south china sea scs during summer is identified both the pattern and strength of the summer asian monsoon wind stress curl over the scs contribute to the interdecadal variability of this current from 1960 to 1979 the monsoon intensified and the zero wind stress curl line shifted southward both the core of positive wind stress curl in the northern scs and the negative curl in the southern scs moved southward and thus induced a southward shift of both the southern anticyclonic and northern cyclonic gyres resulting in a southward displacement of the eastward current associated with these two gyres in the meantime the southern northern scs anticyclonic cyclonic ocean gyre weakened strengthened and therefore also induced the southward shift of the eastward current near the intergyre boundary in contrast the eastward cu

a giant submarine creep zone as a precursor of large scale slope instability offshore the dongsha islands south china sea a giant submarine creep zone exceeding 800 km2 on the continental slope offshore the dongsha islands south china sea is investigated using bathymetric and 3d seismic data tied to borehole information the submarine creep zone is identified as a wide area of seafloor undulations with ridges and troughs the troughs form nw and wnw trending elongated depressions separating distinct seafloor ridges which are parallel or sub parallel to the continental slope the troughs are 0 8 4 7 km long and 0 4 to 2 1 km wide the ridges have wavelengths of 1 4 km and vertical relief of 10 30 m slope strata are characterised by the presence of vertically stacked ridges and troughs at different stratigraphic depths but remaining relatively stationary in their position the interpreted ridges and troughs are associated with large scale submarine creep and the troughs can be divided into three types based on their different internal characters and formation processes the large scale listric faults trending downslope below mtd 1 and horizon t0 may be the potential glide planes for the submarine creep movement high sedimentation rates local fault activity and the frequent earthquakes recorded on the margin are considered as the main factors controlling the formation of this giant submarine creep zone our results are important to the understanding of sediment instability on continental slopes as a the interpreted submarine creep is young or even active at present and b areas of creeping may evolve into large scale slope instabilities as recorded by similar large scale events in the past

proteinaceous corals as proxy archives of paleo environmental change abstract high resolution marine data are critical to evaluating anthropogenic impacts on our environment considering the spatial and temporal limitations of direct instrumental measurements proxy data extracted from marine environmental archives are necessary to separate anthropogenic changes from those that would occur naturally the majority of late holocene high resolution environmental reconstructions are derived from marine carbonates including tropical scleractinian corals bivalves crustose coralline algae and sclerosponges however these archives are restricted to the top hundreds of meters of the water column and only preserve environmental variability that is captured by calcium carbonate skeletons at a very few select locations marine sediments archive annual environmental variability in organic and inorganic materials recently additional types of corals are proving to yield information complimentary to these traditional marine archives including cold water scleractinian corals and proteinaceous corals a taxonomically diverse group the proteinaceous corals are broadly defined as those having a branching gross morphology with skeleton comprised at least partly of protein rich organic material they encode characteristics of their food and ambient environment into the chemical and physical composition of their skeleton this environmental encoding combined with their banded skeleton and significant longevity means that proteinaceous corals hold information in their skeleton that helps fill the spatial and temporal gaps in our knowledge of past and present ocean conditions here i review the environmental reconstructions derived from geochemical measurements of the proteinaceous coral skeletons this information is grouped into the mesopelagic environmental variability captured in the skeleton of bamboo corals surface processes captured in the organic skeletons of corals across all ocean depths and environmental variability documented by skeletal radiometric isotopes we include animals from two separate subclasses within the class anthozoa including the parasitic zoanthids that secrete a sclero proteic skeleton since the proteinaceous corals are taxonomically diverse we consider the unique features that define this group of corals including their distribution morphology nutrition and longevity we find that uncertainty surrounding biological parameters limits the precision of reconstructions derived from the calcitic skeleton in contrast analytical effort and cost constrain the number of reconstructions from the organic skeleton through this discussion we provide insights into the uses challenges and directions for future research for this important environmental archive

a three layer alternating spinning circulation in the south china sea abstractunderstanding of the three dimensional circulation in the south china sea scs is crucial for determining the transports of water masses energy and biogeochemical substances in the regional and adjacent larger oceans the circulation s kinematic and dynamic natures however are largely unclear results from a three dimensional numerical ocean circulation model and geostrophic currents derived from hydrographic data reveal the existence of a unique three layer cyclonic anticyclonic cyclonic cac circulation in the upper 1500 m layers in the scs with differing seasonality an inflow outflow inflow structure in luzon strait largely induces the cac circulation which leads to vortex stretching in the scs basin because of a lateral planetary vorticity flux in each of the respective layers the formation of joint effects of baroclinicity and relief jebar is an intrinsic dynamic response to the cac circulation the jebar arises from the cac flow topog

a global marine fixed nitrogen isotopic budget implications for holocene nitrogen cycling 1 a nitrogen stable isotopic model was constructed in order to constrain the holocene marine fixed nitrogen budget the primary sources and sinks considered were riverine and atmospheric sources nitrogen fixation sedimentary and water column denitrification and sediment burial the source budget was found to be insensitive to changes in nitrogen fixation rates and thus could not be used to constrain this term however the isotopic value of fixed nitrogen losses was very sensitive to the amount of sedimentary denitrification if the isotopic value of marine fixed nitrogen has not changed during the holocene as supported by sedimentary records then in order to balance the isotopic value of sinks and sources approximately 280 tg n yr 1 of sedimentary denitrification is required if such a high rate of denitrification has been sustained throughout the holocene it implies that present day estimates of marine nitrogen fixation are grossly underestimated it also implies that the marine nitrogen budget has a residence time of less than 2000 years