geometry and evolution of salt structures in a marginal rift basin of the gulf of mexico east texas the geometry and distribution of salt structures in the east texas basin shown in an isometric block diagram reveal that a minimum of 1 500 m of mid jurassic louann salt accumulated in a north northeast trending trough floored by thinned continental crust above a threshold thickness of 600 m salt was mobilized by 1 loading beneath a carbonate wedge 2 differential loading by prograding terrigenous clastics and 3 basin edge tilting and erosion salt structures evolved from salt pillows to active diapirs with maximum gross growth rates of 400 to 530 m m y each stage lasted 10 to 30 m y three generations of diapirs were successively activated in different areas by different forces

zonally asymmetric response of the southern ocean mixed layer depth to the southern annular mode interactions between the atmosphere and ocean are mediated by the mixed layer at the ocean surface the depth of this layer is determined by wind forcing and heating from the atmosphere variations in mixed layer depth affect the rate of exchange between the atmosphere and deeper ocean the capacity of the ocean to store heat and carbon and the availability of light and nutrients to support the growth of phytoplankton however the response of the southern ocean mixed layer to changes in the atmosphere is not well known here we analyse temperature and salinity data from argo profiling floats to show that the southern annular mode sam the dominant mode of atmospheric variability in the southern hemisphere leads to large scale anomalies in mixed layer depth that are zonally asymmetric from a simple heat budget of the mixed layer we conclude that meridional winds associated with departures of the sam from zonal symmetry cause anomalies in heat flux that can in turn explain the observed changes of mixed layer depth and sea surface temperature our results suggest that changes in the sam including recent and projected trends attributed to human activity drive variations in southern ocean mixed layer depth with consequences for air sea exchange ocean sequestration of heat and carbon and biological productivity

post miocene rifting and diapirism in the northern red sea abstract rifts and diapirs are the dominant structures in the bathyal zone of the northern red sea where commonly the diapirs ascend along normal faults associated with the rifts in this manner the diapirs form elongated features sometimes exceeding lengths of 30 km and widths of 4 km they also penetrate a sedimentary sequence about 1000 m thickness or less thicknesses generally considered to be barely adequate for the gravity conversion required to initiate diapiric motion we suggest that development of diapirs under these minimal overburden conditions was made possible by the high thermal gradients in the area resulting from the underlying attenuated continental crust and ascending mantle that prevail in the rift system of the northern red sea diapiric evolution was also dependent on the extensional tectonic regime with its numerous normal faults forming weaknesses along which the diapirs could move upwards

tilting history of the san manuel kalamazoo porphyry system southeastern arizona the laramide san manuel kalamazoo porphyry system of arizona has been pivotal in concepts of both extensional tectonics and alteration mineralization zoning this paper reexamines the tilting history in light of new work in the region and reinterprets the geometry of the deposit the porphyry mineralization occurs in and near an intrusion of laramide san manuel porphyry in precambrian oracle granite the area has an extremely complicated history of tertiary crustal extension and fanglomerate deposition but the blocks containing the two main fragments of the original orebody separated by the san manuel fault were involved in only the later parts of this history and are less tilted than other nearby blocks originally horizontal features of mid tertiary age are tilted about 30 degrees those of laramide age about 35 degrees and those of pre laramide age about 45 degrees to the northeast paleomagnetism of the porphyry intrusion itself suggests tilting of about 33 degrees the data thus suggest that postemplacement tilt of the laramide porphyry system was 30 degrees to 35 degrees and that virtually all of it was mid tertiary in age an earlier interpretation of greater tilt magnitude was apparently based in part on correlation with adjacent areas showing greater tilt magnitude as in the tar wash allochthon and in part on a choice of cross section that gives the impression of a nearly recumbent attitude however lowell9s sections are oriented along the strike of both the orebodies and the productive porphyry intrusion which are dipping tablo cylindroidal bodies ore forms a hollow envelope whose inner margin has an aspect ratio of about 4 3 length 2 5 downdip height l limb separation the productive intrusion around which ore is wrapped has a similar aspect ratio in the same plane strike n 58 degrees e dip 47 degrees se reconstruction of the original attitudes of intrusion and ore yields a common strike near n 759 e and a steep dip to the south this is a common attitude for undisturbed productive porphyry dikes of laramide age

triassic evaporites and plio quaternary diapirism in western greece wide triassic evaporite outcrops run parallel to the strike of hellenide thrust faults in western greece they crop out along the leading edges of thrust sheets emplaced as part of the foreland migrating fold and thrust belt the evaporites acted as the plane of decollement for thrust sheet emplacement over much of the external hellenides plio quaternary diapirs occur locally within the broad outcrops of triassic evaporite they are the result of local mobilization of evaporite after its emplacement their rise may have been initially triggered by hellenide thrust sheet loading and subsequently accentuated by plio quaternary subsidence geophysical records and onland exposures show that diapiric rise controlled local sedimentation patterns above the sites of earlier hellenide thrusts the subsequent intrusion of diapirs into these cover sediments caused localized extensional structures to develop this is best seen in se zakinthos where strain hardened conjugate faults developed in friable pliocene sandstones early in the intrusion history principal strains calculated from these sets demonstrate patterns of extension sub orthogonal to intrusion margins they are comparable with patterns known from other field and experimental examples but contrast with some recent studies on diapir related strains

the signature of mesoscale eddies on the air sea turbulent heat fluxes in the south atlantic ocean abstract by collocating 10 years 1999 2009 of remotely sensed surface turbulent heat uxes withsatellite altimetry data we investigate the impact of oceanic mesoscale eddies on the latent and sensibleheat uxesinthesouthatlanticocean instronglyenergeticregions suchasthebrazil malvinascon uenceand the agulhas current retro ection eddies explain up to 20 of the total variance in the surfaceturbulent heat uxes with averaged anomalies of 10 20 w m 2 cyclonic anticyclonic respectively eddies are associated with negative positive heat ux anomalies that tend to cool warm the marineatmospheric boundary layer a composite analysis of the turbulent heat ux anomalies inside the eddiesrevealsadirectrelationshipbetweeneddyamplitudeandtheintensityofsuchanomalies inaddition theseanomaliesarestrongerneartheeddycenter decayingradiallytoreachminimumvaluesoutsidetheeddies 1 introduction the ocean atmosphere system is primarily turbulent in the mesoscale band oceanic eddies play a crucialrole in transporting heat salt momentum and biogeochemical tr acersalongtheirtrajectories signi cantlyimpactingtheoceandynamicsand uxes olson 1991 wunsch 1999 morrowetal 2003 mesoscaleeddiesare coherent rotating features with typical horizontal scales of 50 300 km and time scales ranging fromweeks to months cheltonetal 2011a theyalsoexhibitparticularthermohalineverticalstructuresassoci ated with strong dynamical perturbations of the density and pressure elds olson 1991 chaigneau et al 2011 kurian et al 2011 zhang et al 2013 roullet et al 2014 these perturbations extend up to the seasurface leadingtoanomaliesonseasurfaceheight seasurfacetemperature sst andwindstress amongothers frengeretal 2013 souzaetal 2014 asaresult itisexpectedthateddiesimpacttheair sea uxesandtheoverlayingatmosphericcirculation frengeretal 2013 the turbulent latent lhf and sensible shf heat uxes are the primary processes by which the oceanreleases heat to the atmosphere cayan 1992 both the lhf and shf can be derived from bulk formulaelinking oceanic and atmospheric parameters such as air speci c humidity sst and wind speed to theheat exchanged at the air sea interface liu et al 1979 fairall et al 2003 large and yeager 2009 theanomalies caused by mesoscale eddies in some of these parameters have been recently investigated e g white and annis 2003 hausmann and czaja 2012 frenger et al 2013 souza et al 2014 chelton and xie 2010 although there is ample evidence that oceanic mesoscale features have a signi cant impact onair seaproperties thereisstillalackofknowledgeabouttheirsignatureonthesurfaceturbulentheat uxesandtheirpotentialcontributionstothenetsurfaceheatbudget the recent release of daily satellite based data from the french research institute for exploitation of thesea ifremer bentamy et al 2013 has su cient resolution to estimate the lhf and shf associatedwith mesoscale processes the present work merges satellite altimetry sea level anomaly sla data withremotely sensed surface heat uxes to investigate the impact of mesoscale ocean eddies on the lhf andshfinthesouthatlanticocean sa the sa encompasses both quiescent areas and two regions of intense energetic variability associated withthe presence of large mesoscale eddies figure 1a namely the agulhas current retro ection agr olsonand evans 1986 goni et al 1997 andthebrazil malvinascon uence bmc garzoli and garra o 1989 olson et al 1988 more speci cally we aim i to assess the mean lhf and shf anomalies induced bycyclonicandanticycloniceddiesinthesa ii todescribethespatialvariationsoftheheat uxanomaliesinvillasboasetal

southern ocean thermocline ventilation abstract an approximate mass volume budget in the surface layer of the southern ocean is used to investigate the intensity and regional variability of the ventilation process discussed here in terms of subduction and upwelling ventilation resulting from ekman pumping is estimated from satellite winds the geostrophic mean component is assessed from a climatology strengthened with argo data and the eddy induced advection is included via the parameterization of gent and mcwilliams together with eddy mixing estimates all three components contribute significantly to ventilation finally the seasonal cycle of the upper ocean is resolved using argo data the circumpolar averaged circulation shows an upwelling in the antarctic intermediate water aaiw density classes which is carried north into a zone of dense subantarctic mode water samw subduction although no consistent net production is found in the light samw density classes a large subduction of subtropical mode water stmw is observed the s

regional variations in the influence of mesoscale eddies on near surface chlorophyll eddies can influence biogeochemical cycles through a variety of mechanisms including the excitation of vertical velocities and the horizontal advection of nutrients and ecosystems both around the eddy periphery by rotational currents and by the trapping of fluid and subsequent transport by the eddy in this study we present an analysis of the influence of mesoscale ocean eddies on near surface chlorophyll chl estimated from satellite measurements of ocean color the influences of horizontal advection trapping and upwelling downwelling on chl are analyzed in an eddy centric frame of reference by collocating satellite observations to eddy interiors as defined by their sea surface height signatures the influence of mesoscale eddies on chl varies regionally in most boundary current regions cyclonic eddies exhibit positive chl anomalies and anticyclonic eddies contain negative chl anomalies in the interior of the south indian ocean however the opposite occurs the various mechanisms by which eddies can influence phytoplankton communities are summarized and regions where the observed chl response to eddies is consistent with one or more of the mechanisms are discussed this study does not attempt to link the observed regional variability definitively to any particular mechanism but provides a global overview of how eddies influence chl anomalies

stratal architecture of a halokinetically controlled patch reef complex and implications for reservoir quality a case study from the aptian james limestone in the fairway field east texas basin abstract widespread carbonate platform growth in the cretaceous tethys is associated with expansive reef margin and interior patch reef development these reefs and their associated facies have the potential to be significant hydrocarbon reservoirs but characterization is challenging because of complex facies distributions inadequate understanding of biotic communities and processes impacting their development and difficulties delineating timelines in systems that build their own topography other factors that may impact underlying topography such as tectonics or halokinesis further complicate the story this study delves into these complexities in a dataset from the fairway field a large oil and gas field 115 km2 410 million barrels original oil in place that produces from the aptian james limestone in the east texas basin texas usa the field contains a patch reef complex here defined as an assemblage of patch reefs that grew near each other without necessarily being physically connected that has significant lateral and vertical facies heterogeneity previous attempts at characterization have failed to fully recognize the importance of its proximity to four salt domes which modified topography and influenced deposition prior to and during reef development here we reassess the stratal architecture of the fairway field from a sequence stratigraphic perspective with the goal of augmenting understanding of timing of reef development and facies distributions and ultimately building a better stratigraphic framework for a halokinetically influenced patch reef complex core descriptions and core calibrated wireline log correlation across the field yield a model that explains the relationship between halokinetic topography energy regime relative water depth and reef and reef associated facies development porosity and permeability measurements taken across the field are analyzed to determine best reservoir facies and their distribution the new stratigraphic model is useful for predicting facies architecture in other analogous reef complexes such as those elsewhere in the gulf of mexico and in the middle east its tie to reservoir facies distributions also improves its utility for exploration purposes furthermore this work demonstrates that halokinesis has a major impact on carbonate development and necessitates a new generalized model for halokinetically altered carbonate platforms

a systematic technique for the sequential restoration of salt structures abstract a method is described for the sequential restoration of cross sections in areas of salt tectonics where deformation is confined to the salt and higher layers the subsurface geometry evolves with time through the interaction of various processes sedimentation compaction isostatic adjustment thermal subsidence if present faulting and salt withdrawal diapirism the technique systematically calculates and removes the effects of each of these processes during specified time intervals defined by the interpreted horizons it makes no assumptions about salt kinematics and generally results in the area of the salt layer changing through time the method is described for restoration of extensional terranes but it is also suitable for areas of contractional salt tectonics with only minor modifications after converting an interpreted seismic profile to depth the top layer is stripped off and the underlying section is decompacted according to standard porosity depth functions a deep baseline unaffected by compaction or deformation is used to restore any isostatic compensation or thermal subsidence isostasy is calculated according to the airy model and differential sedimentary loading across a section is shown to be approximately balanced by changes in salt thickness so that the load is evenly distributed after these processes have been reversed the resulting geometry and the seismic data are used to create the sea floor template for structural restoration fault offsets are removed and the layers down to the top salt are restored to this template while the base salt remains fixed the resulting space between the restored top salt and the fixed base salt defines the restored salt geometry in addition the difference between the sea floor template and a fixed sea level provides a measure of the change in water depth ignoring eustatic changes in sea level the technique is applied to an interpreted seismic profile from the eastern green canyon ewing bank area of offshore louisiana the section is characterized by a variety of salt structures including salt rollers a diapiric massif a remnant salt sheet and a salt weld which are shown to have derived from an originally continuous salt sheet which has been modified by sedimentary loading early loading created vertical basin growth that was accommodated primarily by salt withdrawal and associated diapiric rise through the process of downbuilding once the salt weld formed continued sedimentation was accommodated by a lateral increase in basin size caused by down dip extension on listric growth faults

satellite measurements reveal persistent small scale features in ocean winds four year averages of 25 kilometer resolution measurements of near surface wind speed and direction over the global ocean from the quikscat satellite radar scatterometer reveal the existence of surprisingly persistent small scale features in the dynamically and thermodynamically important curl and divergence of the wind stress air sea interaction over sea surface temperature fronts throughout the world ocean is evident in both the curl and divergence fields as are the influences of islands and coastal mountains ocean currents such as the gulf stream generate distinctive patterns in the curl field these previously unresolved features have important implications for oceanographic and air sea interaction research

southern ocean eddy phenomenology mesoscale eddies are ubiquitous features in the southern ocean yet their phenomenology is not well quantified to tackle this task we use satellite observations of sea level anomalies and sea surface temperature sst as well as in situ temperature and salinity measurements from profiling floats over the period 1997 2010 we identified over a million mesoscale eddy instances and were able to track about 105 of them over 1 month or more the antarctic circumpolar current acc the boundary current systems and the regions where they interact are hot spots of eddy presence representing also the birth places and graveyards of most eddies these hot spots contrast strongly to areas shallower than about 2000 m where mesoscale eddies are essentially absent likely due to topographical steering anticyclones tend to dominate the southern subtropical gyres and cyclones the northern flank of the acc major causes of regional polarity dominance are larger formation numbers and lifespans with a contribution of differential propagation pathways of long lived eddies areas of dominance of one polarity are generally congruent with the same polarity being longer lived bigger of larger amplitude and more intense eddies extend down to at least 2000 m in the acc eddies show near surface temperature and salinity maxima whereas eddies in the subtropical areas generally have deeper anomaly maxima presumably inherited from their origin in the boundary currents the temperature and salinity signatures of the average eddy suggest that their tracer anomalies are a result of both trapping in the eddy core and stirring

tectonic history and setting of a seismogenic intraplate fault system that lacks microseismicity the saline river fault system southern united states abstract although the northwest striking saline river fault system of southeastern arkansas is not defined by microseismicity it is associated with sand blows and shows evidence of pleistocene and holocene surface ruptures suggesting a significant seismogenic potential this fault system is within the northern gulf of mexico interior coastal plain a region only recently recognized as containing seismogenic faults to better characterize this active fault system we reconstructed its post paleozoic history using petroleum and coal industry wire line well log and seismic reflection subsurface data the saline river fault system initiated as a series of northwest striking grabens during triassic jurassic uplift and incipient gulf of mexico rifting along the basement alabama oklahoma transform margin of the north american proterozoic craton during post rift subsidence these grabens were buried by gulf sediments until mid cretaceous uplift and igneous activity resulted in minor extensional reactivation of graben faults faulting style changed from extension to transpression during the late cretaceous due to compression of eastern north america as the north atlantic rapidly widened and due to thermal weakening of the alabama oklahoma transform lithospheric discontinuity as it obliquely crossed a mantle hot spot in the late cretaceous graben faults experienced contractional reactivation and steep deeply rooted transpressional faults developed within and parallel to the graben system these transpressional faults locally displace eocene pleistocene and holocene sediments fault activity continues on the saline river fault system due to thin crust along the alabama oklahoma transform and to high heat flow which act together to weaken the crust and promote seismogenic tectonism the fault system may lack appreciable microseismicity because the aftershock sequence of the last large earthquake has had time to dissipate

haynesville and bossier mudrocks a facies and sequence stratigraphic investigation east texas and louisiana usa abstract upper jurassic haynesville and bossier shale gas plays of the northwestern gulf of mexico gom basin produce from organic rich marine transgressive to highstand mudrocks within mixed carbonate clastic depositional systems modern wireline log suites from 200 deep wells were used for detailed correlations and 10 cores throughout the upper kimmeridgian to lower tithonian basin were incorporated into detailed facies stratigraphic and lithologic analyses the haynesville shale lies within a 2nd order transgressive systems tract tst that encompasses back stepping ramp carbonates proximal and marine shales distal below a maximum flooding surface mfs this shale onlaps retrogradational carbonates and basement highs and is capped by the 2nd order mfs bossier shales and local sandstones prograde basinward above the haynesville shale and downlap the 2nd order mfs they grade upward and updip into the thick highstand systems tract hst fluvio deltaic sandstones of the cotton valley group distally organic rich facies developed in restricted bossier environments creating another productive gas shale opportunity several preexisting basement highs in the south and carbonate platforms in the northwest and west restrict and partition the basin thus influencing deposition of highly organic versus nonorganic and siliciclastic dominated versus carbonate dominated lithologies haynesville and bossier shales each compose three upward coarsening cycles that probably represent 3rd order sequences within the larger 2nd order tst and early hst respectively most of the three bossier 3rd order cycles are dominated by varying amounts of siliciclastics deposition of the haynesville mudrocks occurred below storm wave base under mostly dysoxic conditionsm allowing settlement of benthic bivalve communities and bioturbating organisms and oscillating periodically to more anoxic conditions on the seafloor however most of the sparse faunae found in these mudrocks are of planktonic origin bossier mudrocks exhibited more oxygenated and clastic rich lithologies related to progradation of the clastic shoreline and sea level highstand knowledge of lithologic stratigraphic geochemical and faunal variations across mudrock basins needs to be detailed so that shale gas basins might be successfully explored

modification of ocean eddies by air sea interaction a mixed layer model is developed for seasonal time scales and used to investigate the modification of ocean eddies by air sea interaction an eddy is modified by the air sea interaction for the local envionment and the feedback from its surface temperature signal which alters the surface heat and water fluxes this buoyancy forcing tends to decrease the eddy temperature anomaly and seasonal changes in mixed layer depth lead to the surface signal being removed in summer and reappearing in winter the dynamical adjustment of the eddy is assessed by coupling the mixed layer model to a quasi geostrophic model the buoyancy forcing alters the eddy velocity profile and over several seasons may lead to the formation of a subsurface velocity maximum after the spring decrease in mixed layer depth the eddy potential vorticity anomaly is reduced and lateral mixing may subsequently play a role in further eroding the eddy these modelling predictions are supported by the observations of a cold core eddy in the seasonal boundary layer of the northeast atlantic

impact of eddies on surface chlorophyll in the south indian ocean a unique feature of the subtropical south indian ocean is the existence of anticyclonic eddies that have higher chlorophyll concentrations than cyclonic eddies off western australia this anomalous behavior is related to the seeding of anticyclonic eddies with shelf water enriched in phytoplankton biomass and nutrients further off shore two mechanisms have been suggested to explain the eddy chlorophyll relationship i eddies originating from the australian coast maintain their chlorophyll anomaly while propagating westward and ii eddy induced ekman upwelling downwelling enhances dampens nutrient supply in anticyclonic cyclonic eddies here we describe the relationship between eddies and surface chlorophyll within the south indian ocean and discuss possible mechanisms to explain the anomalous behavior in light of new analyses performed using satellite chlorophyll data we show that anticyclonic eddies exhibit higher surface chlorophyll concentration than cyclonic eddies across the entire south indian ocean basin from 20 to 28 s particularly in winter using self organizing maps we analyze the chlorophyll patterns within anticyclonic eddies and cyclonic eddies and highlight their complexity our analysis suggests that multiple mechanisms may underlie the observed eddy chlorophyll relationship based on argo float data we postulate the relationship may be partly related to seasonal adjustment of the mixed layer depth within eddies deeper mixing in anticyclonic eddies is expected to enhance nutrient supply to the mixed layer while shallower mixing in cyclonic eddies is expected to reduce it this could explain why the observed winter surface chlorophyll bloom is stronger in anticyclonic eddies than in cyclonic eddies

basin edge diapirism and updip salt flow in zechstein of southern north sea some unusual and interesting structural geometries have been recognized on seismic lines recorded in the united kingdom sector of the southern permian basin of the north sea they seem to be the result of diapirism at the northern edge of the upper permian zechstein salt basin and involve the preservation of a 75 km 47 mi long prism of a younger mesozoic sequence replaced elsewhere by the widespread jurassic cretaceous late kimmerian unconformity it is suggested that the diapiric features described are due to the movement of salt toward the basin edge having been dammed by a change in facies from basinal halite to shelf lithologies over a short distance

salt tectonics in the norwegian danish basin a study is presented of salt tectonics in a 28 000 km2 area in the norwegian danish basin of the north sea the basin is mainly of permian to early jurassic age and contains sediments which locally reach 8 km in thickness zechstein upper permian salt occurs widely in the basin and has given rise to widespread and intense salt tectonics using seismic reflection sections with a total length of 14 000 km as well as borehole data 86 salt structures have been mapped within the study area the floor of the basin that is the base of the zechstein salt and the faults affecting this floor have also been mapped it is therefore possible to investigate the association of faults and salt structures and hence to ascertain to what extent faulting of the basin floor may have initiated salt movement various lines of investigation and reasoning have been developed to arrive at an estimate of the number of structures for which salt movement is likely to have been initiated by faulting of the basin floor it is found that only for a limited number of salt structures probably about five out of a total of 86 structures the salt movement is likely to have been initiated by faulting the very large majority of the salt structures originated independent of faulting the mechanism responsible for the initiation of salt movement in this majority has also been studied it is found that these salt structures can be divided into two groups one group comprises about 37 salt structures which are randomly distributed nearly all of them are situated where the present basin floor is relatively flat and at its deepest they are thought to be the result of classical halokinesis that is the autonomous upward movement under the influence of gravity of mobile salt at locations where the sedimentary overburden at the time of initial movement was locally less heavy a second group comprises about 43 individual structures which are aligned along nine so called trend lines it is first shown that these trend lines are independent of faults and fault trends in the basin floor the origin of these trends is then discussed by considering two alternative hypotheses for the mechanism responsible for the initiation of salt movement along these trend lines the first hypothesis assumes that salt ridges in the subsurface are initially pushed up by a prograding sedimentary overburden the second hypothesis assumes that initial ridges of mobilized salt are formed along a palaeo depth contour which migrates up the flank of the subsiding basin both hypotheses assume that the salt ridges thus formed can subsequently develop into individual salt structures which produce the observed pattern of trend lines a critical analysis of these two alternative hypotheses leads to the conclusion that the second one involving the concept of a palaeo depth contour which migrates up flank is the more acceptable the mechanism involved may be characterized as a special type of halokinesis namely as halokinesis constrained to operate along a line

wintertime convection in warm core rings thermocline ventilation and the formation of mesoscale lenses large heat losses from warm core ring 82b during february march and april 1982 formed a 400 m thick thermostad in the center of the ring two different models were constructed to simulate the formation of the thermostad water mass properties a one dimensional vertical model forced with a meteorological time series and a volumetric mixing model with climatological input both models indicate that a flux of slope water into the ring is necessary to yield the observed thermostad salinities the subsequent slow decay of the ring core in the slope water suggests that such winter convected rings can easily maintain the warm band water identified by wright and parker 1976 the large loss of core water during interactions with the gulf stream suggests that the reabsorption of such winter cooled warm rings is an important source of high salinity high oxygen anomalies in the main thermocline of the sargasso sea the volume of water in a typical ring reabsorption is sufficient to generate many 20 intrathermocline eddies with t s properties close to those of recently reported lenses this suggests that many of these small eddies are much more local in origin and may be more highly dissipative than has previously been suggested an estimate of the flux of high salinity high oxygen water into the main thermocline by this mechanism leads to ventilation at a rate that is a significant fraction of the ekman pumping at these density levels thus the reabsorption of winter cooled warm core rings by the gulf stream is an important eddy ventilation mechanism for the sargasso sea

mimoc a global monthly isopycnal upper ocean climatology with mixed layers a monthly isopycnal mixed layer ocean climatology mimoc global from 0 to 1950 dbar is compared with other monthly ocean climatologies all available quality controlled profiles of temperature t and salinity s versus pressure p collected by conductivity temperature depth ctd instruments from the argo program ice tethered profilers and archived in the world ocean database are used mimoc provides maps of mixed layer properties conservative temperature absolute salinity sa and maximum p as well as maps of interior ocean properties sa and p to 1950 dbar on isopycnal surfaces a third product merges the two onto a pressure grid spanning the upper 1950 dbar adding more familiar potential temperature and practical salinity s maps all maps are at monthly 0 5 0 5 resolution spanning from 80 s to 90 n objective mapping routines used and described here incorporate an isobath following component using a fast marching algorithm as well as front sharpening components in both the mixed layer and on interior isopycnals recent data are emphasized in the mapping the goal is to compute a climatology that looks as much as possible like synoptic surveys sampled circa 2007 2011 during all phases of the seasonal cycle minimizing transient eddy and wave signatures mimoc preserves a surface mixed layer minimizes both diapycnal and isopycnal smoothing of s as well as preserves density structure in the vertical pycnoclines and pycnostads and the horizontal fronts and their associated currents it is statically stable and resolves water mass features fronts and currents with a high level of detail and fidelity

thermal evolution of the north central gulf coast the subsidence history of the north louisiana salt basin determined from well data indicates that the region underwent extension during rifting and has since passively subsided due to conductive cooling of the lithosphere timing of the rifting event is consistent with opening of the gulf of mexico during late triassic to early jurassic time crustal extension by a factor of 1 5 to 2 was computed from tectonic subsidence curves however data from the early subsidence history are insufficient to distinguish between uniform and nonuniform extension of the lithosphere the magnitude of extension is in good agreement with total sediment and crustal thicknesses from seismic refraction data in the adjacent central mississippi salt basin the temperature distribution within the sediments is calculated using a simple heat conduction model temperature and subsidence effects of thermal insulation by overlying sediments are included the computed temperature distribution is in good agreement with bottom hole temperatures measured in deep wells temperature histories predicted for selected stratigraphic horizons within the north louisiana salt basin suggest that thermal conditions have been favorable for hydrocarbon generation in the older stata results from a two dimensional heat conduction model suggest that a probable cause for the early formation of the adjacent uplifts is lateral heat conduction from the basin rapid extension of the lithosphere underneath areas with horizontal dimensions of 50 100 km produces extremely rapid early subsidence due to lateral heat conduction the moderate subsidence rate observed in the north louisiana salt basin during the jurassic and early cretaceous suggests slow extension over a long period of time

satellite observations of chlorophyll phytoplankton biomass and ekman pumping in nonlinear mesoscale eddies nonlinear mesoscale eddies can influence biogeochemical cycles in the upper ocean through vertical and horizontal advection of nutrients and marine organisms the relative importance of these two processes depends on the polarity of an eddy cyclones versus anticyclones and the initial biological conditions of the fluid trapped in the core of the eddy at the time of formation eddies originating in the eastern south indian ocean are unique in that anticyclones typically associated with downwelling contain elevated levels of chlorophyll a enhanced primary production and phytoplankton communities generally associated with nutrient replete environments from analysis of 9 years of concurrent satellite measurements of sea surface height chlorophyll phytoplankton carbon and surface stress we present observations that suggest eddy induced ekman upwelling as a mechanism that is at least partly responsible for sustaining positive phytoplankton anomalies in anticyclones of the south indian ocean the biological response to this eddyinduced ekman upwelling is evident only during the austral winter during the austral summer the biological response to eddy induced ekman pumping occurs deep in the euphotic zone beyond the reach of satellite observations of ocean color

relaxation of continental lithosphere an explanation for late cretaceous reactivation of the sabine uplift of louisiana texas with few unconstrained assumptions a simple quantitative model for flexural isostasy between two crustal blocks of different thickness that subsequently undergoes partial relaxation of accumulated stress can explain reactivation of the sabine uplift in the mid cretaceous thin salt over the sabine uplift indicates that it was a positive area in the middle jurassic but began to subside during the late jurassic during the late jurassic and early cretaceous the sabine uplift had no topographic expression and was the center of a large flat bottomed basin covering most of east texas and north louisiana reactivation of the sabine uplift in the mid cretaceous caused a minimum of 150 m of uplift and extensive erosion of lower cretaceous rocks during the late cretaceous and tertiary the sabine uplift resumed subsiding but at a slower rate than the adjacent basins since the mid cretaceous the sabine uplift has risen more than 1 km relative to the east texas basin we suggest that this structural history is consistent with the following simple quantitative model for flexural isostasy during formation of the gulf of mexico in the late triassic early jurassic by rifting and extension of the lithosphere brittle deformation of the crust created small scale wavelength of tens of kilometers lateral variations in crustal thickness initially the newly formed margin was in point wise airy isostatic equilibrium thus synrift and or early postrift subsidence was characterized by a series of rift valleys or half grabens separated by uplifts however as the margin cooled and contracted the lithosphere became stronger and subsequent loading was regionally compensated thus postrift subsidence was characterized by a broad regional downwarp if at some later point in time the rigid portion of the lithosphere was weakened or relaxed then lateral density variations would have been recompensated at shorter wavelengths thus areas of little or no crustal extension would have been uplifted and areas of high extension would have experienced additional subsidence gravity and total tectonic subsidence interpretations agree that the sabine uplift region is underlain by thicker crust than the adjacent east texas and north louisiana basins possible mechanisms for relaxation of continental lithosphere are thermal rejuvenation horizontal in plane stress viscous relaxation and extensional faulting

the episodic rise net growing rate and kinematics of radial faults of the salinas de oro diapir using paleoseismological techniques ne spain salt upwelling versus karstic subsidence abstract this paper explores the use of trenching and paleoseismological techniques to determine salt flow rates into a salt diapir for the first time in the literature the salinas de oro diapir located in the northern spanish pyrenees is an oval shaped triassic salt stock that extends vertically for 7 km down to the paleozoic basement salt dissolution subsidence and diapir growth are coeval active processes karstification is responsible for the development of large sinkholes a thick caprock and the monocline folding and ring faulting of the cretaceous and early tertiary limestone rim the evaporite karstic aquifer discharges high concentration water of up to 137 g l of total dissolved solids and a conductivity over 200 ms cm into the salado creek which drains the diapir top the salinity monitoring of this drainage provides a maximum karstic surface lowering rate of around 2 8 mm yr salt upwelling has caused the 150 m uplift of the annular limestone escarpment and the development of 3000 m long radial grabens with up to 90 m of vertical offset that disrupt drainages displace quaternary deposits and overprint concentric faults the 260 cm drag folding of lacustrine facies exposed in a 42 m long and 6 5 m deep trench due to the creep motion of the western radial fault of azanza graben yielded a minimum short term uplift slip rate of 1 75 mm yr for the last 1485 years and provides a minimum salt supply rate of over 5 mm yr considering karstification lowering this value that is several hundred times higher than average evidence the discontinuous growth of salinas de oro diapir

geomorphic and stratigraphic evidence of quaternary diapiric activity enhanced by fluvial incision navarres salt wall and graben system se spain abstract the structural and stratigraphic geological features associated with salt structures have received extensive attention from geologists however there is limited work on the geomorphic and quaternary record of diapiric activity despite its practical implications e g salt and hydrocarbon extraction geostorage activities this work analyses the quaternary geomorphic and stratigraphic evidence of diapiric activity in the navarres salt wall se spain developed along the axis of a neogene graben this salt system is located in a region characterized by a peculiar network of orthogonal grabens that control the configuration and evolution of the drainage network the protruding salt walls are spatially associated with the erosionally unloaded and deeply entrenched graben sections situated close to the regional base level evidence of recent current activity in the navarres salt wall include 1 internally drained areas in a marginal withdrawal basin with long sustained aggradation 2 distorted drainage network defeated and deflected streams wind gaps knickpoints changes in fluvial style which changed from an initial axial longitudinal pattern to a longitudinal marginal distribution at the flanks of the salt wall 3 development of diapiric fault scarps at the edge of the salt wall 4 tilted fluvial terraces dipping away from the salt wall and with localized sediment thickening the available data indicate along strike variability in deformation style and long term vertical deformation rates these range from 0 09 mm yr to significantly higher values 0 2 0 4 mm yr in the section where the salt wall displays a more prominent relief and is affected by deep fluvial entrenchment the regional analysis and the characterization of the navarres salt wall suggest that quaternary diapirism in the region is enhanced by erosional unloading related to fluvial entrenchment which expands from the regional base level through the upstream propagation of an incision wave

syn to post rift diapirism and minibasins of the central high atlas morocco the changing face of a mountain belt the atlas mountains are classically regarded as a failed mesozoic rift arm subject to alpine inversion folding and thrusting here we present new integrated structural and sedimentological studies that have revealed numerous early middle jurassic diapiric ridges and minibasins characterized by distinctive halokinetic structures diachroneity in halokinesis is observed across the central high atlas waning first in the sw during the early middle jurassic jbel azourki and tazoult ridges and continuing to late middle jurassic towards the ne imilchil region the halokinetic structures are readily differentiated from the effects of later alpine deformation allowing a new picture of the central high atlas to emerge the most pervasive deformation in the central high atlas is associated with early middle jurassic diapirism whereas the impact of alpine inversion is mostly focused at the basin margins this new understanding helps explain previously problematic aspects of the atlas mountains which we now recognize as an exceptionally well exposed natural laboratory for understanding the interactions between halokinesis tectonics and sedimentation

evolution of the destin dome offshore florida north eastern gulf of mexico abstract structural and stratigraphic relationships indicated by seismic reflection data suggest that uplift of the destin dome anticline resulted mainly from salt movement during late cretaceous to early cenozoic time a thick succession of lower cretaceous sediment was deposited in the central part of the basin seaward of the present day destin dome sediment loading squeezed the salt both updip onto the shelf and downdip into the basin a step in the pre salt basement limited movement of salt and controlled the location of the dome vertical movement of salt was accommodated by extensional faulting during the early cenozoic sediment touchdown onto the pre salt basement formed a salt weld between the anticline and the de soto canyon diapir field cut off the supply of salt and stopped growth of the structure the minimum accumulation thickness of the mother salt is estimated to be 760 m and the original volume of salt deposited at the present day location of the destin dome anticline on the florida shelf is estimated to be 1000 km3 the volume of salt in place today is in excess of 2300 km3

basin architecture salt tectonics and upper jurassic structural styles desoto canyon salt basin northeastern gulf of mexico despite awareness of the importance of continental extension during rifting there are few quantitative studies that show the influence of crustal extension on basin architecture the distribution of salt and late jurassic sedimentation in the desoto canyon salt basin northeastern gulf of mexico application of simplified isostatic principles using a lithospheric buoyancy model allow quantification of total tectonic subsidence crust thickness crustal extension and crust type interpretation of over 4800 km of migrated multifold seismic reflection profiles and well data integrated with computed isostatic relations provide the basis to characterize middle jurassic callovian age salt halokinetic processes and to describe the structural development of overlying upper jurassic strata an average crustal thickness of 25 km and crustal extension s values between 1 4 and 1 8 suggest the sedimentary succession is underlain by moderately stretched and attenuated continental crust the widespread distribution and geometry of dipping subsalt reflectors particularly in the shelfal areas provide evidence for a late triassic early jurassic phase of rifting prior to deposition of middle jurassic salt the distribution of autochthonous salt and the overlying upper jurassic sediments reflect the presalt structural imprint and suggest that the basic architecture of the basin was established by the middle jurassic following significant attenuation of the crust although deposition occurred in a slowly subsiding stable marginal setting salt movement and associated growth faulting are the most significant tectonic elements affecting the stratigraphic and structural development of the overlying strata faults related to growth of salt structures root at the base of salt in what appears to be a common detachment or decollement for salt movement the original distribution of salt is widespread and sheetlike with an estimated minimum thickness of 760 m progressive basinward subsidence of the margin and differential sediment loading by the overburden are the primary mechanisms initiating mobilization of salt and subsequent deformation of sediments during the late jurassic and from the late cretaceous through the early cenozoic

evolution of salt structures east texas diapir province part 1 sedimentary record of halokinesis post aptian post 112 ma strata in the east texas basin were strongly influenced by halokinesis and therefore record the evolution of associated salt structures dome induced changes in patterns of sandstone distribution depositional facies and reef growth indicate that thickness variations in strata surrounding domes were caused by syndepositional processes rather than by tectonic distortion salt domes in the east texas basin exhibit three stages of growth pillow diapir and post diapir each of which affected surrounding strata differently pillow growth caused broad uplift of strata over the crest of the pillows the resulting topographic swell influenced depositional trends and was susceptible to erosion fluvial channel systems bypassed pillow crests and stacked vertically in primary peripheral sinks on the updip flanks of the pillows diapir growth was characterized by expanded sections of shelf and deltaic strata in secondary peripheral sinks around the diapirs lower cretaceous reefs on topographic saddles between secondary peripheral sinks now host major oil production at fairway field post diapir crestal uplifts and peripheral subsidence affected smaller areas than did equivalent processes during pillow or diapir stages documented facies variations over and around domes at different stages of growth enable prediction of subtle facies controlled hydrocarbon traps facies controlled traps are likely to be the only undiscovered ones remaining in mature petroliferous basins such as the east texas basin

mapping ground deformation over houston galveston texas using multi temporal insar abstract houston galveston hg region in texas has been subsiding due to the combined effects of groundwater withdrawal hydrocarbon extraction salt dome movement and faulting this human and partially nature induced ground deformation has gradually threatened the stability of urban infrastructure and caused the loss of wetland habitat along the gulf of mexico interferometric synthetic aperture radar insar techniques can measure ground motions in high spatial resolution over large coverage the purpose of this study is to map the spatial and temporal variations in surface deformation around the hg region using a multi temporal insar mti technique and to assess the role of fluid withdrawal groundwater withdrawal and hydrocarbon extraction salt tectonics and fault activity in land surface deformation mti derived land surface deformation measurements are then compared to gps and extensometer observations geologic and hydrologic data and information about hydrocarbon extraction to address the causes of the observed deformation the mti measurements based on ers 1 2 datasets have mapped regional subsidence up to 53 mm yr in the northwestern hg as well as a slight uplift at 20 mm yr in the southeastern hg from 1993 to 2000 insar measurements obtained from envisat and alos data reveal subsidence rate of up to 30 mm yr over the northwestern hg between 2004 and 2011 our results indicate that the pattern of ground deformation was nearly concentric around locations of intense groundwater withdrawal and the spatial extent of the subsiding area has been shrinking and migrating toward the northeast after 2000 we have resolved localized ground subsidence cones over hydrocarbon exploration fields which were likely caused by reservoir compaction we have differentiated ground surface deformation over salt domes which was due to ongoing differential movement of individual salt spines we have identified 5 40 mm yr differential subsidence across a number of faults in the region these faults functioned as water barriers disrupting the integrity of ground water flow and aggravating localized surface displacements

wintertime convection in a gulf stream warm core ring abstract wintertime convection creates deep mixed layers which determine the water mass characteristics and potential vorticity for waters in the main pycnocline of the world ocean diabatic cooling is most intense in the northern hemisphere near the northwestern boundary of subtropical gyres where outbreaks of cold dry continental air over warm surfaces waters produce large sensible and latent heat losses from the ocean gulf stream warm core rings containing warm salty sargasso sea water are cast off to the north of the gulf stream in close proximity to the northeastern coast of north america we have observed the convective cooling of one these rings 821 during january 1982 from the usns bartlett during one cold air outbreak we calculate a net surface hear loss from the ring to the atmosphere of 800 w m 2 and a deepening of the surface mixed layer form 50 to 190 m the heat budget for the ring required a lateral heat exchange with the surrounding slope water in order to achieve a balanced heat bu

hydrocarbon generation and migration routes in the east texas basin the east texas basin is a prolific mature hydrocarbon province producing oil and gas from several reservoirs and a variety of trap types many of the liquid hydrocarbons discovered in the basin are trapped in structures related to movement of the underlying louann salt by determining the structural evolution of the basin we constructed a framework to model the generation of hydrocarbons in the basin geochemical data indicate three major oil types jurassic oil lower cretaceous oil and upper cretaceous oil the jurassic source is mature throughout the basin and began to expel oil at approximately 88 ma the distribution of jurassic oil in cretaceous reservoirs shows that vertical migration routes predominated prospective lower cretaceous source rocks are only matur in the deep central portion of the basin where expulsion began about 47 ma distribution of this oil type suggests that lower cretaceous source rocks occur only in localized areas of the east texas basin organic rich upper cretaceous shales are immature in the main part of the basin but are mature south of the angelina caldwell flexure where they reached peak generation at approximately 20 ma long distance lateral migration routes are necessary to explain the distribution of this oil type migration routes to the giant east texas field may be 100 km or more modeling of this basin suggests an exploration approach in mature basins of defining migration pathways and seeking traps astride them traps in this position have a better probability of being filled and all else being equal are likely to be better fields than traps located away from the major migration routes

southern ocean mixed layer depth from argo float profiles 1 argo float profiles of temperature salinity and pressure are used to derive the mixed layer depth mld in the southern ocean mld is determined from individual profiles using both potential density and potential temperature criteria and a monthly climatology is derived from individual mlds using an objective mapping method quantitative data are available in the auxiliary material the spatial structures of mlds are similar in each month with deep mixed layers within and just north of the antarctic circumpolar current acc in the pacific and indian oceans the deepest mixed layers are found from june to october and are located just north of the acc where antarctic intermediate water aaiw and subantarctic mode water samw are formed examination of individual mlds indicates that deep mixed layers mld 400 m from both the density and temperature criteria are concentrated in a narrow surface density band which is within the density range of samw the surface salinity for these deep mixed layers associated with the samw formation are slightly fresher compared to historical estimates differences in air sea heat exchanges wind stress and wind stress curl in the pacific and indian oceans suggest that the mode water formation in each ocean basin may be preconditioned by different processes wind mixing and ekman transport of cold water from the south may assist the samw formation in the indian ocean in the eastern pacific the formation of mode water is potentially preconditioned by the relative strong cooling and weak stratification from upwelling

model for salt deformation on deep margin of central gulf of mexico basin based on available nonexclusive seismic data a preliminary model has been developed for salt deformation on the deep margin of the central gulf of mexico basin in this model the tertiary clastic wedge prograded to the basinward limit of original jurassic salt by the middle miocene as the salt and overburden thinned basinward lateral flow combined with a strong component of downward force exerted by subsiding voluminous middle miocene loading caused the basinward limit of the louann salt to effectively shear off deposition of the upper miocene and pliocene sediments was confined primarily shoreward of an incipient salt swell but pleistocene sediments were eventually able to breach the barrier deformation of the detached salt produced the features present on the slope today preliminary work indicates that most of the detached salt was propelled basinward and upsection toward the present sigsbee escarpment leaving pinch and swell salt structures behind the various types of residual salt structures have been formed as a result of differences in the history of sedimentary loading different stages of development of pinch and swell structures shown on seismic sections illustrate this model

evolution of salt structures east texas diapir province part 2 patterns and rates of halokinesis the effects of salt mobilization on aptian and younger post 112 ma strata in the east texas basin can be used to illustrate patterns of dome growth through time and to estimate rates and amounts of salt movement pre aptian domes grew in three areas around the margin of the diapir province apparently in pre aptian depocenters maximum dome growth along the basin axis coincided with maximum regional sedimentation there during the middle cretaceous aptian albian and cenomanian in the late cretaceous the sites of maximum diapirism migrated to the periphery of the diapir province diapirism began after pillows were erosionally breached leading to salt extrusion and formation of peripheral sinks the duration of pillow and diapir stages of growth was subequal ranging from 10 to 30 ma post diapiric stage of growth continued for more than 112 ma in some cases diapirs grew fastest in the early cretaceous when peak growth rates ranged from 150 to 530 m ma 490 to 1 740 ft ma declining in the early tertiary to 10 to 60 m ma 30 to 200 ft ma assuming steady state conditions over periods of 1 to 17 ma strain rates for the rise of the east texas diapirs averaged 6 7 10 16 sec peak gross rate of growth averaged 2 3 10 15 sec similar to slow orogenic rates the evolution of east texas salt domes essentially ended in the early tertiary with uplift rates less than 30 m ma 100 ft ma