a strike slip fault corridor within the alpujarra mountains betic cordilleras spain in a long corridor in the internal zone of the betic cordilleras bounded to the north by the sierra nevada and to the south by the sierras lujar contraviesa and gador two discernible bands of strike slip faults exist these bands lie in an approximately e w direction and are well exposed throughout and beyond the 85 km long belt the characteristic features of strike slip faults such as cataclastic rocks composed of variously textured fault breccia which also include fragments of rocks up to several metres in size incipient foliation and striation demonstrate the right lateral nature of the displacement there are also fractures which run in a nw se and nne ssw direction and apparently originated after formation of the e w faults the magnitude of lateral displacements is difficult to calculate evidence of considerable vertical movement can be found locally these strike slip displacements have essentially occurred since the middle miocene period and might still be taking place

geology and tectonics of the betic zone se spain abstract the southern margin of the iberian continent comprises a complex geological history which can be traced back into the proterozoic when a gneissic basement was formed a cover of nevado filabride rocks was deposited onto this proterozoic basement during the palaeozoic the permian intrusion of the bedar granite suggests that the palaeozoic sedimentary rocks now exposed in the betic cordilleras have been affected by the hercynian orogeny similar to that of palaeozoic rocks in the adjoining ossa morena zone the hercynian basement was probably covered by alpujarride carbonates in the mesozoic when rifting opened tethys and intruded 140 ma old basic dyke swarms the palaeozoic basement of the betic cordilleras comprises a suture of late cretaceous subduction 80 85 ma b p this can be inferred from hp lt metamorphic facies obducted in coeval thrust slices of nevado filabride rocks the nevado filabride nappes include mesozoic carbonates transformed into marbles macael the suture was probably annnealed after the closure of tethys the mesozoic boundary between africa and europe and the rifting in tethys ceased during the palaeogene when the atlas mountains were formed 36 ma b p subsequently relative movements between africa and europe in the neogene were accommodated by strike slip faults these define the iberian microplate moving eastward by atlantic spreading and possibly subducting under italy neogene deformation of iberia is most intensive in southeastern spain due to emplacement of a mantle diapir under the alboran area this occurred early in the neogene aquitanian and caused nappe spreading involving alpujarride and malaguide rocks the subsequent neogene history has now been studied in great detail and is reviewed here it involves clear examples of calc alkaline volcanism most probably not related to subduction seismic motion along strike slip faults within the iberian microplate and syntectonic deposition in intermontane neogene basins

rapid circulation of warm subtropical waters in a major glacial fjord in east greenland the recent rapid increase in mass loss from the greenland ice sheet is primarily attributed to an acceleration of outlet glaciers oceanographic data obtained in summer 2008 show that subtropical waters that reside year round in the shelf ocean off greenland continuously enter a large glacial fjord in east greenland and contribute to melting at the glacier terminus the recent rapid increase in mass loss from the greenland ice sheet1 2 is primarily attributed to an acceleration of outlet glaciers3 4 5 one possible cause of this acceleration is increased melting at the ice ocean interface6 7 driven by the synchronous warming8 9 10 of subtropical waters offshore of greenland however because of the lack of observations from greenland s glacial fjords and our limited understanding of their dynamics this hypothesis is largely untested here we present oceanographic data collected in sermilik fjord east greenland by ship in summer 2008 and from moorings our data reveal the presence of subtropical waters throughout the fjord these waters are continuously replenished through a wind driven exchange with the shelf where they are present all year the temperature and renewal of these waters indicate that they currently cause enhanced submarine melting at the glacier terminus key controls on the melting rate are the volume and properties of the subtropical waters on the shelf and the patterns of along shore winds suggesting that the glaciers acceleration has been triggered by a combination of atmospheric and oceanic changes our measurements provide evidence for a rapid advective pathway for the transmission of oceanic variability to the ice sheet margins

subaqueous melting of store glacier west greenland from three dimensional high resolution numerical modeling and ocean observations we present three dimensional high resolution simulations of ice melting at the calving face of store glacier a tidewater glacier in west greenland using the massachusetts institute of technology general circulation model we compare the simulated ice melt with an estimate derived from oceanographic data the simulations show turbulent upwelling and spreading of the freshwater laden plume along the ice face and the vigorous melting of ice at rates of meters per day the simulated august 2010 melt rate of 2 0 0 3 m d is within uncertainties of the melt rate of 3 0 1 0 m d calculated from oceanographic data melting is greatest at depth above the subglacial channels causing glacier undercutting melt rates increase proportionally to thermal forcing raised to the power of 1 2 1 6 and to subglacial water flux raised to the power of 0 5 0 9 therefore in a warmer climate store glacier melting by ocean may increase from both increased ocean temperature and subglacial discharge key points simulated melt agrees with estimates from a hydrographic survey of the glacier with more runoff glaciers will melt faster at constant ocean temperature 2013 american geophysical union all rights reserved

ocean forcing of the greenland ice sheet calving fronts and patterns of retreat identified by automatic satellite monitoring of eastern outlet glaciers 1 we have developed an automatic method to identify changes in the position of calving glacier margins using daily modis imagery application of the method to 32 ocean terminating glaciers in east greenland produced 26 802 margin positions for a 10 year long period 2000 2009 we report these high resolution data and show that the glaciers exhibit seasonal cycles with magnitudes of advance and retreat proportional to glacier width despite similar seasonality there is a distinct difference between the interannual trends of calving front positions north and south of 69 n all glaciers above this latitude showed very limited or no change when seasonality was excluded while glaciers south of 69 n retreated significantly between 2001 and 2005 2 3 km on average approximately 26 of the retreat of southern glaciers was regained by readvance from 2005 to 2009 to explain the latitudinal boundary of glacier dynamics we review basic climatic factors including summer and winter atmospheric forcing sea ice conditions and ocean temperature we conclude that the southern retreats were strongly influenced by warm oceanic conditions associated with increased transport of subtropical waters to the irminger sea and to fjords and coastal regions south of 69 n northern glaciers remained stable despite significant increase in runoff in this region because fjords at latitudes higher than 69 n are less exposed to subtropical waters the southern retreats illustrate sensitive behavior of calving glaciers and we hypothesize that the calving fronts retreated because they were exposed to rapid ice front melting

palaeostress analysis of the northern nijar and southern vera basins constraints for the neogene displacement history of major strike slip faults in the betic cordilleras se spain this paper presents the results of a detailed structural analysis of the northern nijar and southern vera basins with special emphasis on the evolution of the regional stress field and the associated timing of movement of the serrata gafarillos and palomares strike slip fault zones these major fault zones control the neogene deformation of the se internal betic cordilleras in spain detailed stress analysis on neogene sediments of the vera and nijar basins shows a strike slip regime with nw se oriented subhorizontal maximum principal stress 1 during tortonian and earliest messinian times under the influence of this stress field dextral displacement along the n090e trending gafarillos fault zone resulted in deformation of the sediments of the southern sorbas and northeastern nijar basins during the early messinian a clock wise rotation of the stress field occurred stress analysis in rocks with late early messinian up to quaternary ages in the nijar and vera basins indicates a strike slip regime with n s oriented subhorizontal maximum principal stress 1 under the influence of this stress field the main activity along the n010e striking palomares strike slip fault zone took place resulting in deformation of the neogene sediments of the southeastern vera basin and culminating in a maximum sinistral displacement of more than 20 km at the same time the stress field was not suitably oriented to exert a large shear component on the gafarillos fault zone which activity ended after the earliest messinian fault and outcrop patterns of syntectonic neogene sediments in the vera basin show that displacement along the palomares fault zone decreased at the end of the middle miocene although minor displacement phases may still have occurred during the late miocene and possibly even pliocene from the middle miocene onward deformation in the nijar basin was controlled by sinistral displacement along the n040e trending serrata strike slip fault zone

controls on the transport of oceanic heat to kangerdlugssuaq glacier east greenland this work was funded by nerc grant ne k014609 1 to peter nienow and andrew sole and a nerc studentship to donald slater edward hanna and david wilton acknowledge support from nerc grant ne h023402 1

linear response of east greenland s tidewater glaciers to ocean atmosphere warming predicting the retreat of tidewater outlet glaciers forms a major obstacle to forecasting the rate of mass loss from the greenland ice sheet this reflects the challenges of modeling the highly dynamic topographically complex and data poor environment of the glacier fjord systems that link the ice sheet to the ocean to avoid these difficulties we investigate the extent to which tidewater glacier retreat can be explained by simple variables air temperature meltwater runoff ocean temperature and two simple parameterizations of ocean atmosphere forcing based on the combined influence of runoff and ocean temperature over a 20 y period at 10 large tidewater outlet glaciers along the east coast of greenland we find that ocean atmosphere forcing can explain up to 76 of the variability in terminus position at individual glaciers and 54 of variation in terminus position across all 10 glaciers our findings indicate that i the retreat of east greenland s tidewater glaciers is best explained as a product of both oceanic and atmospheric warming and ii despite the complexity of tidewater glacier behavior over multiyear timescales a significant proportion of terminus position change can be explained as a simple function of this forcing these findings thus demonstrate that simple parameterizations can play an important role in predicting the response of the ice sheet to future climate warming

neotectonics and morphotectonics of the southern almeria region betic cordillera spain kinematic implications most previous studies related to the recent tectonic development of southeastern betic cordillera and in particular the south of almeria agree with the kinematic variety that can be observed in the post miocene structures at different scales this variety is difficult to explain if we consider only the regional stress field related to the convergence of the eurasian and african plates that remained relatively steady over the last 9 ma this work proposes a block tectonics with horizontal and vertical relative movements driven by strike slip movements of major faults to explain the variety of kinematics observed in the area from middle miocene to present the combined activity of the alpujarras fault zone dextral strike slip and the carboneras fault zone sinistral strike slip induces within the major block bounded by them the squeezing of minor pre existing fault bounded crustal blocks this process generates traction areas inside the escaping block which are linked with the existence of gradients of westward movement rate this tectonics can explain some of the structures related with the extensional tectonics predominant in the south of almeria province and the development of the minor and major morphostructures driven by faults with different kinematics the tectonics of blocks proposed is useful to give a coherent interpretation of apparently incoherent local structural data into a regional and homogeneous compressional stress field

a simple model of fjord and coastal circulation interaction abstract the dynamical interaction of a narrow fjord with a wind driven coastal regime is investigated using a linear two layer numerical model the coriolis acceleration is important in the coastal regime but assumed to he unimportant in the fjord dynamical because v 0 for a wide variety of wind conditions bottom topography and model parameters the wind forced coastal circulation with its geostrophic alongshore currants has a strong effect on the circulation within the fjord these geostrophic currents control the free surface and pycnocline displacement at the fjord mouth thereby strongly affecting fjord circulation this mechanism is an alternative to the classical idea of hydraulic control at the mouth by sills or constrictions model simulators also show that the free surface slope is a baroclinic effect and that alongshore and across shore winds affect the fjord differently alongshore winds produce flooding while up and down fjord winds simply sat up the surface we find that offshore win

distributed subglacial discharge drives significant submarine melt at a greenland tidewater glacier this is the publisher s final pdf the article is copyrighted by american geophysical union and published by john wiley sons inc it can be found at http agupubs onlinelibrary wiley com agu journal 10 1002 28issn 291944 8007

hydrogeochemical processes in an arid region of europe almeria se spain abstract in the lower andarax river basin 3 aquifer units have been defined namely the carbonate aquifer the deep aquifer and the detrital aquifer which between them contain a wide variety of water types identification of hydrogeochemical processes has been performed by studying a series of ionic ratios comprising the principal constituents together with b and li cl vs so4 cl vs mg cl vs li b vs li among the processes detected the circulation of groundwaters with high concentrations of so4 was found to have significant effects moreover in the coastal region naturally occurring processes related to the flushing of saline waters from sediments of marine origin occur in conjunction with others clearly of human origin that are related to saltwater intrusion a further factor is the entry from overlying deposits of waters with a high saline content this salinity is related to the flushing of sediments of marine origin the use of b and li together enables waters in which salinity is related to seawater to be distinguished from others in which salinity is related to evaporitic layers or to thermal areas the concentration of li is directly related to water temperature while that of b is greater in the most saline sectors of gypsiferous and or seawater origin

estimating ocean heat transports and submarine melt rates in sermilik fjord greenland using lowered acoustic doppler current profiler ladcp velocity profiles submarine melting at the ice ocean interface is a significant term in the mass balance of marine terminating outlet glaciers however obtaining direct measurements of the submarine melt rate or the ocean heat transport towards the glacier that drives this melting has been difficult due to the scarcity of observations as well as the complexity of oceanic flows here we present a method that uses synoptic velocity and temperature profiles but accounts for the dominant mode of velocity variability to obtain representative heat transport estimates we apply this method to the sermilik fjord helheim glacier system in southeastern greenland using lowered acoustic doppler current profiler ladcp and hydrographic data collected in summer 2009 we find a mean heat transport towards the glacier of 29 10 9 w implying a submarine melt rate at the glacier face of 650 m a 1 t he resulting adjusted velocity profile is indicative of a multilayer residual circulation where the meltwater mixture flows out of the fjord at the surface and at the stratification maximum

tectonic significance of the present relief of the betic cordillera abstract tortonian calcarenites of the betic cordillera were deposited in coastal or very shallow marine environments and represent an ideal marker for estimating vertical movements from the late miocene to the present a map showing the heights at which these tortonian marine rocks are situated has a clear correlation with the present relief indicating that today s relief has been formed since the tortonian there is also a good correlation between present relief and the bouguer anomaly distribution in the betic cordillera as well as with crustal thickness likewise the present relief is directly related to the geodynamic setting of a horizontal n s to nnw sse compression and an almost perpendicular extension along with isostatic readjustment existing in the betic cordillera from the tortonian as a result of these regional stresses faults and folds have produced notable vertical movements the highest rates of uplift of the betic cordillera coincide with large antiforms in particular those of the sierra nevada and the sierra filabres several subsiding sectors also exist for example the granada basin or the guadalquivir basin the foreland guadalquivir basin has a complex history because the uplift in its eastern sector and subsidence in the western sector coexisted during the late tortonian today the whole betic cordillera is characterized by differential regional uplift even in the aforementioned subsiding sectors

syn tectonic sedimentation in a neogene strike slip basin containing a stacked gilbert type delta se spain abstract the pliocene sedimentation in the cerro blanco ei barranquete subbasin cbb subbasin that forms part of the larger almeria nijar carboneras basin anc basin is controlled by a releasing overstep and a restraining zone in the ne trending serrata strike slip fault zone the sedimentary development of this subbasin can be considered in three stages of a fault kinematic model during stage i a wave influenced shoaling zone was present in front of an emergent serrata cape to the ne with a basin to the sw and w uplift of the shoaling zone in a restraining n080e trending cerro blanco fault zone cb fault zone is evidenced by the following syn tectonic sedimentary phenomena a a rotational unconformity towards the nw b four deepening pulses in the shallow water zone c massflow deposits originating from a near coastal zone possibly triggered by tectonic pulses during stage ii the uplifted zone became increasingly shallow and finally emerged quartz pebbles in the sediments that indicate a land connection between the serrata cape and the metamorphic basement in the north differentiate this stage from the previous one prograding shoreline deposits marked the outbuilding of the serrata cape towards the sw an episodically subsiding zone due to a releasing overstep between the sinistral n040e trending nw serrata boundary fault nwsb fault and b fault during stage ila is indicated by a southwestward outbuilding fandelta during this stage there was only one depocentre during stage ilb the depocentre of the subsiding zone split up this shifting of depocentres is explained according to the releasing overstep model by an increase of the overlap between the nwsb fault and the b fault during stage iii the cbb subbasin became continental and was inverted as demonstrated by its present day relief the area was severely faulted by n040e trending r and y shears on a metre scale which led to an estimated cumulative sinistral displacement of 2 km since fandelta deposition the present day activity of the nwsb fault is shown by sinistrally deflected stream courses and pressure ridges

lateral interaction between metamorphic core complexes and less extended tilt block domains the alpujarras strike slip transfer fault zone betics se spain abstract the alpujarras area in southeastern spain exhibits one of the scant documented examples of extension related strike slip faults bordering core complexes in the world faults of the alpujarras fault zone define a regional scale complex ene striking transfer zone that marks the boundary among the sierra nevada elongated dome a highly extended constricted core complex and a less extended domain formed by large scale tilt blocks detailed mapping and structural analysis show that the alpujarras fault zone is an integral part of the wsw directed normal fault systems that thinned the betic hinterland during the middle miocene to recent time fault patterns and palaeostress analysis both indicate that dextral movement along the strike slip faults was induced by a local stress field with a sub horizontal e w to ese wnw trending maximum principal stress axis which is synchronous with the regional stress field driving the normal fault systems palaeostress analysis also indicates subsequent variations in the stress field with a sub horizontal nw se to n s trending maximum principal stress axis thus producing both the tectonic inversion of the northern fault of the alpujarras system and shortening of the unloaded extensional detachment footwall a simplified kinematic model for the tectonic evolution of the alpujarras area from the middle miocene to recent emphasizes the kinematic coupling of normal faults and strike slip transfer zones in the extensional process

characteristics of ocean waters reaching greenland s glaciers interaction of greenland s marine terminating glaciers with the ocean has emerged as a key term in the ice sheet mass balance and a plausible trigger for their recent acceleration our knowledge of the dynamics however is limited by scarcity of ocean measurements at the glacier ocean boundary here data collected near six marine terminating glaciers 79 north kangerdlugssuaq helheim and petermann glaciers jakobshavn isbrae and the combined sermeq kujatdleq and akangnardleq are compared to investigate the water masses and the circulation at the ice ocean boundary polar water of arctic origin and atlantic water from the subtropical north atlantic are found near all the glaciers property analysis indicates melting by atlantic water aw found at the grounding line depth near all the glaciers and the influence of subglacial discharge at depth in summer aw temperatures near the glaciers range from 4 58c in the southeast to 0 168c in northwest greenland consistent with the distance from the subtropical north atlantic and cooling across the continental shelf a review of its offshore variability suggests that aw temperature changes in the fjords will be largest in southern and smallest in northwest greenland consistent with the regional distribution of the recent glacier acceleration

fold and fault interactions during the development of an elongated narrow basin the almanzora neogene quaternary corridor se betic cordillera spain 1 elongated corridors grow in different tectonic settings mainly in areas deformed by fold and fault sets parallel to the borders the almanzora corridor however is a good example of an e w elongated asymmetrical narrow basin developed in a changing stress scenario generated by the interaction of fold and fault sets oriented parallel and oblique to the corridor borders the initial crustal thickening process was mainly related to the development of the e w oriented sierra de los filabres large antiform which constitutes a major heterogeneity during the tortonian a nw se convergent tectonic setting oblique to this already emerged antiform gives rise to a large dextral simple shear band that determines the development of a major fold las estancias antiform the asymmetrical location of minor tectonic structures faults and minor folds and the distribution of sedimentation denudation areas that finally configure the almanzora corridor synform furthermore development of nw se oriented normal faults points to ne sw orthogonal extension in a new stress field oblique to the corridor borders this region illustrates that the elongated character of the corridors may persist inherited from the orientation of previous crustal rheological heterogeneities in addition marine transgression may be produced in compressional settings favored by the synform development during initial stages of crustal thickening finally led to the relief uplift

convection driven melting near the grounding lines of ice shelves and tidewater glaciers subglacial meltwater draining along the bed of fast flowing marine terminating glaciers emerges at the groundingline wheretheiceeithergoesafloattoformaniceshelforterminates inacalvingface theinputof freshwater to the ocean provides a source of buoyancy and drives convective motion alongside the ice ocean interface this process is modeled using the theory of buoyant plumes that has previously been applied to the study of the larger scale circulation beneath ice shelves the plume grows through entrainment of ocean waters and the heat brought into the plume as a result drives melting at the ice ocean interface the equations are nondimensionalized by using scales appropriate for the region where the subglacial drainage rather than the subsequent addition of meltwater supplies the majority of the buoyancy forcing it is found that the melt rate within this region can be approximated reasonably well by a function that is linear in ocean temperature has a cube root dependence on the flux of subglacial meltwater and has a complex dependency on the slope of the ice ocean interface the model is used to investigate variability in melting induced by changes in both ocean temperature and subglacial discharge for a number of realistic examples of ice shelves and tidewater glaciers the results show how warming ocean waters and increasing subglacial drainage both generate increases in melting near the grounding line

partitioning effects from ocean and atmosphere on the calving stability of kangerdlugssuaq glacier east greenland we use the 7 km retreat of kangerdlugssuaq glacier kg east greenland to examine the mechanisms interactions and relative significance of atmospheric forcing and ice ocean interactions hydrographic data from 1991 1993 and 2004 show that subtropical waters are common in kangerdlugssuaq fjord kf and that surface waters were warm in 2004 relative to 1991 and 1993 the main water column was nonetheless warmest in 1991 we contend that while flow of subtropical waters into fjords provides a setting in which rapid glacier retreat can occur the triggering of retreat depends on additional environmental factors the climatic variables standing out in our study of kg and kf are air temperature and katabatic winds both had strong positive anomalies during winter 2004 05 when kg retreated we show that proglacial ice melange was absent and that fjord freeze up did not occur until 11 april 2005 due to warm and windy conditions we demonstrate that this setting is unusual and hypothesize that exposure to open water in winter months caused the retreat calculation of ice front melt rates shows that discharge of basal meltwater first from runoff and subsequently from frictional basal heating should intensify the interaction between glacier and fjord

modeling turbulent subglacial meltwater plumes implications for fjord scale buoyancy driven circulation abstractfjord scale circulation forced by rising turbulent plumes of subglacial meltwater has been identified as one possible mechanism of oceanic heat transfer to marine terminating outlet glaciers this study uses buoyant plume theory and a nonhydrostatic three dimensional ocean ice model of a typical outlet glacier fjord in west greenland to investigate the sensitivity of meltwater plume dynamics and fjord scale circulation to subglacial discharge rates ambient stratification turbulent diffusivity and subglacial conduit geometry the terminal level of a rising plume depends on the cumulative turbulent entrainment and ambient stratification plumes with large vertical velocities penetrate to the free surface near the ice face however midcolumn stratification maxima create a barrier that can trap plumes at depth as they flow downstream subglacial discharge is varied from 1 750 m3 s 1 large discharges result in plumes with positive temperature and salinity anomalies in the upper water column for

rapid and synchronous ice dynamic changes in east greenland two major outlet glaciers in east greenland have suddenly begun to accelerate and retreat the speeds of kangerdlugssuaq and helheim remained steady during the 1990s despite progressive and substantial thinning but have abruptly increased within the last two years more than doubling ice flux to the ocean had it been an isolated example the comparable 1998 speed up of jakobshavn isbra in west greenland might have been explained simply by its chance retreat past a pinning point now that two further greenland outlets have exhibited similar behavior a common process seems likely a remarkable correspondence in the inter annual patterns of speed and ice front variation between kangerdlugssuaq and helheim implies a significant sensitivity to regional environmental factors the period of continued warming and thinning appears to have primed these glaciers for a step change in dynamics not included in current models we should expect further greenland outlet glaciers to follow suit copyright 2006 by the american geophysical union

the dynamics of shelf forcing in greenlandic fjords abstractthe fjords that connect greenland s glaciers to the ocean are gateways for importing heat to melt ice and for exporting meltwater into the ocean the transport of heat and meltwater can be

active tectonics in the sierra nevada betic cordillera se spain insights from geomorphic indexes and drainage pattern analysis article i nfo the sierra nevada of the central betic cordillera is a 3000 m high mountain range surrounded by neogene quaternary sedimentary basins having been uplifted since late miocene times the southern and western mountain fronts of the sierra nevada are fault bounded while the northern one is an unconformity between the neogene quaternary sediments of the guadix baza basin and the metamorphic rocks of the nevado filabride complex we have carried out a geomorphic study by examining drainage patterns and characteristics of mountain fronts in order to reveal areal variations and styles of rock uplift mountain front sinuosity smf area altitude relations hypsometric curves and valley floor entrenchment differ significantly between the northern western and southern mountain fronts the lack of important faults along the northern sierra nevada mountain front together with the elevated topographic position of the guadix baza basin average altitude is around 1100 m points to similar uplift of both geomorphic units sierra and basin in a single large scale crustal block the asymmetry factors show systematic asymmetries at both sides of the lanjaron river probably due to the presence of an active nne ssw oriented antiform in the western sierra nevada finally river profiles indicate maximal river entrenchment in the western part of the sierra nevada probably related to the uplift of the footwall of the padul niguelas fault system therefore our geomorphic analysis suggests that the western part of the sierra nevada is tectonically active by means of a combination of normal faults along the mountain front and nne ssw oriented active folds which in turn likely have a gravitational origin related to the exhumation of the footwall of the normal fault system

ice melange dynamics and implications for terminus stability jakobshavn isbrae greenland 1 we used time lapse imagery seismic and audio recordings iceberg and glacier velocities ocean wave measurements and simple theoretical considerations to investigate the interactions between jakobshavn isbrae and its proglacial ice melange the melange behaves as a weak granular ice shelf whose rheology varies seasonally sea ice growth in winter stiffens the melange matrix by binding iceberg clasts together ultimately preventing the calving of full glacier thickness icebergs the dominant style of calving and enabling a several kilometer terminus advance each summer the melange weakens and the terminus retreats the melange remains strong enough however to be largely unaffected by ocean currents except during calving events and to influence the timing and sequence of calving events furthermore motion of the melange is highly episodic between calving events including the entire winter it is pushed down fjord by the advancing terminus at 40 m d 1 whereas during calving events it can move in excess of 50 103 m d 1 for more than 10 min by influencing the timing of calving events the melange contributes to the glacier s several kilometer seasonal advance and retreat the associated geometric changes of the terminus area affect glacier flow furthermore a force balance analysis shows that large scale calving is only possible from a terminus that is near floatation especially in the presence of a resistive ice melange the net annual retreat of the glacier is therefore limited by its proximity to floatation potentially providing a physical mechanism for a previously described near floatation criterion for calving

near glacier surveying of a subglacial discharge plume implications for plume parameterizations at tidewater glaciers plume dynamics affect submarine melting fjord circulation and the mixing of meltwater models often rely on buoyant plume theory to parameterize plumes and submarine melting however these parameterizations are largely untested due to a dearth of near glacier measurements here we present a high resolution ocean survey by ship and remotely operated boat near the terminus of kangerlussuup sermia in west greenland these novel observations reveal the 3d structure and transport of a near surface plume originating at a large undercut conduit in the glacier terminus that is inconsistent with axisymmetric plume theory the most common representation of plumes in ocean glacier models instead the observations suggest a wider upwelling plume a truncated line plume of 200 m width with higher entrainment and plume driven melt compared to the typical axisymmetric representation our results highlight the importance of a subglacial outlet s geometry in controlling plume dynamics with implications for parameterizing the exchange flow and submarine melt in glacial fjord models

an improved mass budget for the greenland ice sheet extensive ice thickness surveys by nasa s operation icebridge enable over a decade of ice discharge measurements at high precision for the majority of greenland s marine terminating outlet glaciers prompting a reassessment of the temporal and spatial distribution of glacier change annualmeasurements for 178 outlet glaciers reveal that despite widespread acceleration only 15 glaciers accounted for 77 of the 739 29 gt of ice lost due to acceleration since 2000 and four accounted for 50 among the top sources of loss are several glaciers that have received little scientific attention the relative contribution of ice discharge to total loss decreased from 58 before 2005 to 32 between 2009 and 2012 as such 84 of the increase in mass loss after 2009 was due to increased surface runoff these observations support recentmodel projections that surface mass balance rather than ice dynamics will dominate the ice sheet s contribution to 21st century sea level rise

differences in paleomagnetic interpretations due to the choice of statistical demagnetization and correction techniques kapuskasing structural zone northern ontario canada abstract the kapuskasing structural zone ksz reveals a section through the archean lower crustal granoblastic gneisses our new paleomagnetic data largely agree with previous work but we show that interpretations vary according to the choices of statistical demagnetization and field correction techniques first where the orientation distribution of characteristic remanence directions on the sphere is not symmetrically circular the commonly used statistical model is invalid fisher r a proc r soc a217 1953 295 any tendency to form an elliptical distribution indicates that the sample is drawn from a bingham type population bingham c 1964 distributions on the sphere and on the projective plane phd thesis yale university fisher and bingham statistics produce different confidence estimates from the same data and the traditionally defined mean vector may differ from the maximum eigenvector of an orthorhombic bingham distribution it seems prudent to apply both models wherever a non fisher population is suspected and that may be appropriate in any tectonized rocks non fisher populations require larger sample sizes so that focussing on individual sites may not be the most effective policy in tectonized rocks more dispersed sampling across tectonic structures may be more productive second from the same specimens mean vectors isolated by thermal and alternating field af demagnetization differ which treatment gives more meaningful results is difficult to decipher especially in metamorphic rocks where the history of the magnetic minerals is not easily related to the ages of tectonic and petrological events in this study thermal demagnetization gave lower inclinations for paleomagnetic vectors and thus more distant paleopoles third of more parochial significance tilt corrections may be unnecessary in the ksz because magnetic fabrics and thrust ramp are constant in orientation to the depth at which they level off at approximately 15 km depth with archean geothermal gradients primary remanences were blocked after the foliation was tilted to rise on the thrust ramp therefore the rocks were probably magnetized in their present orientation tilting largely or entirely predates magnetization

north atlantic warming and the retreat of greenland s outlet glaciers mass loss from the greenland ice sheet quadrupled over the past two decades contributing a quarter of the observed global sea level rise increased submarine melting is thought to have triggered the retreat of greenland s outlet glaciers which is partly responsible for the ice loss however the chain of events and physical processes remain elusive recent evidence suggests that an anomalous inflow of subtropical waters driven by atmospheric changes multidecadal natural ocean variability and a long term increase in the north atlantic s upper ocean heat content since the 1950s all contributed to a warming of the subpolar north atlantic this led in conjunction with increased runoff to enhanced submarine glacier melting future climate projections raise the potential for continued increases in warming and ice mass loss with implications for sea level and climate

characteristics and dynamics of two major greenland glacial fjords the circulation regimes of two major outlet glacial fjords in southeastern greenland sermilik fjord sf and kangerdlugssuaq fjord kf are investigated using data collected in summer 2009 the two fjords show similar flow patterns with a time dependent vertically sheared flow structure dominating over the background estuarine flow driven by buoyancy input we show that this time dependent flow is consistent with circulation induced by density interface fluctuations at the fjord mouth often referred to as intermediary circulation one difference between the fjords is that the hydrographic and velocity structure below a surface modified layer is found to be three layer in kf in summer compared to two layer in sf outside each fjord large scale geostrophic currents dictate the stratification at the mouth although the way in which these large scale flows impinge on each fjord is distinct combining the observations with estimates from existing theories we find the magnitudes of the estuarine qe and intermediary qi circulation and show that qi qe although along fjord winds can also be significant we expect that the critical parameter determining qi qe is the sill depth compared to the fjord depth with shallower sills corresponding to weaker intermediary circulation finally we discuss the implications of strong intermediary circulation on calculating heat transport to the glacier face and its potential feedbacks on the background circulation in these highly stratified estuaries

changes in the velocity structure of the greenland ice sheet using satellite radar interferometry observations of greenland we detected widespread glacier acceleration below 66 north between 1996 and 2000 which rapidly expanded to 70 north in 2005 accelerated ice discharge in the west and particularly in the east doubled the ice sheet mass deficit in the last decade from 90 to 220 cubic kilometers per year as more glaciers accelerate farther north the contribution of greenland to sea level rise will continue to increase

a two dimensional glacier fjord coupled model applied to estimate submarine melt rates and front position changes of hansbreen svalbard we have developed a two dimensional coupled glacier fjord model which runs automatically using elmer ice and mitgcm software packages to investigate the magnitude of submarine melting along a vertical glacier front and its potential influence on glacier calving and front position changes we apply this model to simulate the hansbreen glacier hansbukta proglacial fjord system southwestern svalbard during the summer of 2010 the limited size of this system allows us to resolve some of the small scale processes occurring at the ice ocean interface in the fjord model using a 0 5 s time step and a 1 m grid resolution near the glacier front we use a rich set of field data spanning the period april august 2010 to constrain calibrate and validate the model we adjust circulation patterns in the fjord by tuning subglacial discharge inputs that best match observed temperature while maintaining a compromise with observed salinity suggesting a convectively driven circulation in hansbukta the results of our model simulations suggest that both submarine melting and crevasse hydrofracturing exert important controls on seasonal frontal ablation with submarine melting alone not being sufficient for reproducing the observed patterns of seasonal retreat both submarine melt and calving rates accumulated along the entire simulation period are of the same order of magnitude 100 m the model results also indicate that changes in submarine melting lag meltwater production by 4 5 weeks which suggests that it may take up to a month for meltwater to traverse the englacial and subglacial drainage network

geodetic evidence for continuing tectonic activity of the carboneras fault se spain abstract the carboneras fault zone cfz is a prominent onshore offshore strike slip fault that forms part of the eastern betic shear zone ebsz located in se spain in this work we show for the first time the continuing tectonic activity of the cfz and quantify its geodetic slip rates using continuous and campaign gps observations conducted during the last decade we find that the left lateral motion dominates the kinematics of the cfz with a strike slip rate of 1 3 0 2 mm yr along the n48 direction the shortening component is significantly lower and poorly constrained recent onshore and offshore paleoseismic and geomorphic results across the cfz suggest a minimum late pleistocene to present day strike slip rate of 1 1 mm yr considering the similarity of the geologic and geodetic slip rates measured at different points along the fault the northern segment of the cfz must have been slipping approximately at a constant rate during the quaternary regarding the eastern alpujarras fault zone corridor afz located to the north of the cfz our gps measurements corroborate that this zone is active and exhibits a right lateral motion these opposite type strike slip motion across the afz and cfz is a result of a push type force due to nubia and eurasia plate convergence which in turn causes the westward escape of the block bounded by these two fault zones

oceanic heat delivery via kangerdlugssuaq fjord to the south east greenland ice sheet acceleration of the greenland ice sheet gris tidewater outlet glaciers has increased the ice sheet s contribution to global sea level rise over the last two decades coincident increases in atmospheric temperatures around greenland explain some of the increased ice loss but warm atlantic origin water aw is increasingly recognized as contributing to the accelerating ice mass loss particularly via the outlet glaciers of south east se greenland however there remains a lack of understanding of the variability in heat content of the water masses found to the east of greenland and how this heat is communicated to the outlet glaciers of the gris here a new analysis is presented of ocean gris interaction in which the oceanic heat flux toward the ice sheet in kangerdlugssuaq fjord 0 26 tw is an order of magnitude greater than that reported for the other major outlet glacier of se greenland helheim heat delivered by aw to the calving front of kangerdlugssuaq is equivalent to 10 m d 1 melt i e 30 60 of the ice flow speed and thus is highly significant during the observational campaign in september 2010 warm polar surface water psww melted a substantial volume of ice within the fjord equivalent to 25 of the volume melted by aw alone satellite derived sea surface temperatures show large interannual variability in psww over the 20 year period 1991 2011 anomalously warm psww was observed within the fjord prior to the well documented major ice front retreats of may 2004 and november 2010

impact of fjord dynamics and glacial runoff on the circulation near helheim glacier greenland to show that the melting circulation is affected by seasonal runoff from the glacier and by the fjord s externally forced currents and stratification the presence of light arctic and dense atlantic waters in the fjord in particular causes meltwater to be exported at depth and influences the vertical distribution of heat along the ice margin our results indicate that the melting circulation is more complex than hypothesized and influenced by multiple external parameters we conclude that the shape and stability of greenland s glaciers may be strongly influenced by the layering of the arctic and atlantic waters in the fjord as well as their variability

seasonal speedup of a greenland marine terminating outlet glacier forced by surface melt induced changes in subglacial hydrology we present subdaily ice flow measurements at four gps sites between 36 and 72 km from the margin of a marine terminating greenland outlet glacier spanning the 2009 melt season our data show that 35 km from the margin seasonal and shorter time scale ice flow variations are controlled by surface melt induced changes in subglacial hydrology following the onset of melting at each site ice motion increased above background for up to 2 months with resultant up glacier migration of both the onset and peak of acceleration later in our survey ice flow at all sites decreased to below background multiple 1 to 15 day speedups increased ice motion by up to 40 above background these events were typically accompanied by uplift and coincided with enhanced surface melt or lake drainage our results indicate that the subglacial drainage system evolved through the season with efficient drainage extending to at least 48 km inland during the melt season while we can explain our observations with reference to evolution of the glacier drainage system the net effect of the summer speed variations on annual motion is small 1 this in part is because the speedups are compensated for by slowdowns beneath background associated with the establishment of an efficient subglacial drainage system in addition the speedups are less pronounced in comparison to land terminating systems our results reveal similarities between the inland ice flow response of greenland marine and land terminating outlet glaciers

structure of alluvial valleys from 3 d gravity inversion the low andarax valley almeria spain test case this paper presents a gravimetric study based on 382 gravimetric stations in an area about 32 km2 of a nearly flat basin the low andarax valley this alluvial basin close to its river mouth is located in the extreme south of the province of almeria and coincides with one of the existing depressions in the betic cordillera the paper presents new methodological work to adapt a published inversion approach growth method to the case of an alluvial valley sedimentary stratification with density increase downward the adjusted 3d density model reveals several features in the topography of the discontinuity layers between the calcareous basement 2 700 kg m3 and two sedimentary layers 2 400 and 2 250 kg m3 we interpret several low density alignments as corresponding to se faults striking about n140 145 e some detected basement elevations such as the one previously known by boreholes in viator village are apparently connected with the fault pattern the outcomes of this work are 1 new gravimetric data 2 new methodological options and 3 the resulting structural conclusions

oceanic boundary conditions for jakobshavn glacier part i variability and renewal of ilulissat icefjord waters 2001 14 jakobshavnglacier west greenland has respondedtotemperaturechangesinilulissaticefjord intowhich it terminates thisstudycollectedhydrographicobservationsinsideilulissaticefjordandfromadjacentdiskobay between2001and2014 thewarmestdeepdiskobaywaterswereblockedbytheentrancesillanddidnotreach jakobshavn glacier in the fjord basin the summer mean temperature was 2 88c from 2009 to 2013 excluding 2010 whenitwas 18c cooler despitethisvariability summerpotential densities in the basinwereinthe narrow range of 27 20 su 27 31kgm 23 and basin water properties matched those of disko bay in this layer each summer this relation has likely held since at least 1980 basin waters from 2009 and 2011 13 were therefore similar tothosein1998 99 whenjakobshavn glacier began toretreat whilebasin watersin2010wereascoolas in the 1980s the 2010 basin temperature anomaly was advected into disko bay not produced by local atmospheric variability this anomaly also shows that ilulissat icefjord basin waters were renewed annually or faster time series fragments inside the fjord did not capture the 2010 anomaly but show that the basin temperatures varied little subannually outside of summer fjord velocity profiles from summer 2013 implied a basin renewal time scale of about 1 month in model simulations of the fjord circulation subglacial discharge from jakobshavn glacier could drive renewal of the fjord basin over a single summer while baroclinic forcing from outside the fjord could not because of the sill at the mouth

the treatment of meltwater retention in mass balance parameterisations of the greenland ice sheet retention of melt water runoff by percolation and or refreezing in the snowpack cannot be neglected when studying the surface mass balance of the greenlandice sheet in this paper we make a detailed comparison of several treatments proposed in the literature to account for this process in large scale mass balanceparameterizations the melt on the greenland ice sheet is calculated with a revised degree day model using updated datasets of surface elevation and precipitationrate on a 5 km grid crucial model parameters are recalibrated by comparing mass balance characteristics with available observations on a regional basis wediscuss the role of meltwater retention in the light of the overall mass balance of the greenland ice sheet and its sensitivity to climatic change and displaypatterns of effective retention fractions for the various methods as a main conclusion it appears that overall results are quite similar for the various models butthat meltwater retention has a large spatial variation not described by the simple treatments using the most comprehensive retention model the sensitivity of therunoff is found to be 0 35 mm deg c of sea level change per year we also present a new map of the different zones facies that characterize the accumulationarea of the greenland ice sheet that is useful for interpreting field data and calibrating satellite observations

rapid changes in ice discharge from greenland outlet glaciers using satellite derived surface elevation and velocity data we found major short term variations in recent ice discharge and mass loss at two of greenland s largest outlet glaciers their combined rate of mass loss doubled in less than a year in 2004 and then decreased in 2006 to near the previous rates likely as a result of fast re equilibration of calving front geometry after retreat total mass loss is a fraction of concurrent gravity derived estimates pointing to an alternative source of loss and the need for high resolution observations of outlet dynamics and glacier geometry for sea level rise predictions

modeling thermodynamic ice ocean interactions at the base of an ice shelf abstract models of ocean circulation beneath ice shelves are driven primarily by the heat and freshwater fluxes that are associated with phase changes at the ice ocean boundary their behavior is therefore closely linked to the mathematical description of the interaction between ice and ocean that is included in the code an hierarchy of formulations that could be used to describe this interaction is presented the main difference between them is the treatment of turbulent transfer within the oceanic boundary layer the computed response to various levels of thermal driving and turbulent agitation in the mixed layer is discussed as is the effect of various treatments of the conductive heat flux into the ice shelf the performance of the different formulations that have been used in models of sub ice shelf circulation is assessed in comparison with observations of the turbulent heat flux beneath sea ice formulations that include an explicit parameterization of the oceanic boundary layer give results that

modeling the impact of glacial runoff on fjord circulation and submarine melt rate using a new subgrid scale parameterization for glacial plumes the injection at depth of ice sheet runoff into fjords may be an important control on the frontal melt rate of tidewater glaciers here we develop a new parameterization for ice marginal plumes within the massachusetts institute of technology general circulation model mitgcm allowing three dimensional simulation of large 500 km2 glacial fjords on annual or longer time scales we find that for an idealized fjord without shelf driven circulation subglacial runoff produces a thin strong and warm down fjord current in the upper part of the water column balanced by a thick and slow up fjord current at greater depth although submarine melt rates increase with runoff due to higher melt rates where the plume is in contact with the ice front we find that annual submarine melt rate across the ice front is relatively insensitive to variability in annual runoff better knowledge of the spatial distribution of runoff controls on melt rate in those areas not directly in contact with plumes and feedback mechanisms linking submarine melting and iceberg calving are necessary to more fully understand the sensitivity of glacier mass balance to runoff driven fjord circulation

the matachewan dyke swarm canada an early proterozoic magnetic field reversal abstract consistent age relationships between oppositely magnetized dykes of the 2 45 ga matachewan dyke swarm suggest that only a single magnetic field reversal occurred during the period of igneous activity the magnetic field throughout most of this time was characterized by a ssw declination and shallow negative inclination but reversed toward the waning stages of magmatism the new paleomagnetic data provide the oldest known magnetic reversal for which the relative reversal sense is known

orthogonal folding of extensional detachments structure and origin of the sierra nevada elongated dome betics se spain 1 a close relationship of the kinematics and timing between low angle extensional faulting and upright folding is established for the miocene detachment systems in the hinterland of the betics in southeastern spain folding accompanied tectonic denudation developing elongated domes with fold axes both parallel and perpendicular to the direction of extension the geometry kinematics and tectonic evolution of two major sequentially developed extensional fault systems have been characterized in several e w elongated mountain ranges of the central betics on the basis of new cartographic and structural data and a comprehensive revision of other available geological and geophysical observations the extensional systems have an average wsw direction of extension and led to exhumation of the two lower metamorphic complexes of the betics the nevado filabride and the alpujarride during the middle and upper miocene serravallian to tortonian the extended domain contains a core complex with distal and proximal antiformal hinges separated by around 60 km and with a fold amplitude of 6 km measured parallel to the direction of extension the total amount of extension across the core complex is about 109 116 km corresponding to a stretching factor of 3 5 3 9 estimated using the distance between fold axial surfaces and a geometrical model accomplishing footwall deformation during tectonic denudation via subvertical simple shear the elongated domal and basinal geometry of the detachments and their respective footwalls is due to the interference between two sets of orthogonal large scale open folds trending n s and e w longitudinal n s trending folds are interpreted as isostatic folds i e folds that developed in response to differential unloading of the extensional detachment footwalls inducing ductile flow in the middle crust these folds formed in a rolling hinge anticline in which rotation migrates westward through the footwall as it is progressively unroofed in contrast e w trending folds being subparallel to the direction of extension have a contractional origin and progressively affect to the west the isostatically readjusted segments of the detachments once they are inactive orthogonal folding occurred since the serravallian to lower pliocene extension is still active from the rolling hinge anticline in sierra nevada to the west the middle miocene to pliocene tectonic evolution of the sierra nevada elongated dome at the core of the betic hinterland is another example of the coexistence of extension and contraction during continued overall convergence and mountain building

neogene evolution of the sorbas basin se spain determined by paleostress analysis abstract the neogene subsidence history of the sorbas basin situated in the internal zone of the betic cordilleras of southeastern spain is strongly controlled by strike slip deformation the sedimentary sequence of the basin offers a good control on the timing of separate phases of fault activation the southern border of the sorbas basin is formed by a major east west trending fault zone the gafarillos fault zone which consists of intermixed slivers of pre neogene basement blocks and neogene basin sediments fault patterns and paleostress analysis both indicate that major displacement along this fault zone was dextral with a n310e oriented maximum principal stress axis strike slip movement along the east west oriented faults ended during the earliest messinian after a minimum of 6 ma of activation paleostress analysis indicates a subsequent phase of strike slip fault movement present in sites of up to early pliocene age the maximum principal stress axis orientation is n350e for this phase this deformation is synchronous with sinistral displacement along the palomares fault zone situated directly to the east of the study area subsequently our paleostress analysis indicates an extensional regime during the late pliocene to quaternary however extensional tensors were calculated at a number of sites possibly representing local stress regimes coexisting with the main strike slip deformation and sorbas basin subsidence folding of tortonian sediments points out that local compressional deformation took place as well during the neogene basin history observed wide ranges for the ellipsoid shapes of the calculated tensors support the existence of lateral stress variations

threefold increase in marine terminating outlet glacier retreat rates across the atlantic arctic 1992 2010 accelerated discharge through marine terminating outlet glaciers has been a key component of the rapid mass loss from arctic glaciers since the 1990s however glacier retreat and its climatic controls have not been assessed at the pan arctic scale consequently the spatial and temporal variability in the magnitude of retreat and the possible drivers are uncertain here we use remotely sensed data acquired over 273 outlet glaciers located across the entire atlantic arctic i e areas potentially influenced by north atlantic climate and or ocean conditions specifically greenland novaya zemlya franz josef land and svalbard to demonstrate high magnitude accelerating and near ubiquitous retreat between 1992 and 2010 overall mean retreat rates increased by a factor of 3 5 between 1992 and 2000 30 5 m a 1 and 2000 10 105 8 m a 1 with 97 of the study glaciers retreating during the latter period the retreat was greatest in northern western and south eastern greenland and also increased substantially on the barents sea coast of novaya zemlya glacier retreat showed no significant or consistent relationship with summer air temperatures at decadal timescales the rate of frontal position change showed a significant but weak correlation with changes in sea ice concentrations we highlight large variations in retreat rates within regions and suggest that fjord topography plays an important role we conclude that marine terminating arctic outlet glaciers show a common response of rapid and accelerating retreat at decadal timescales

simple tidal prism models revisited simple tidal prism models for well mixed estuaries have been in use for some time and are discussed in most text books on estuaries the appeal of this model is its simplicity however there are several flaws in the logic behind the model these flaws are pointed out and a more theoretically correct simple tidal prism model is derived in doing so it is made clear which effects can in theory be neglected and which can not

on the nature and variability of the east greenland spill jet a case study in summer 2003 abstractresults from a high resolution 2 km numerical simulation of the irminger basin during summer 2003 are presented the focus is on the east greenland spill jet a recently discovered component of the circulation in the basin the simulation compares well with observations of surface fields the denmark strait overflow dso and the hydrographic structure of typical sections in the basin the model reveals new aspects of the circulation on scales of o 0 1 10 days and o 1 100 km the model spill jet results from the cascade of dense waters over the east greenland shelf spilling can occur in various locations southwest of the strait and it is present throughout the simulation but exhibits large variations on periods of o 0 1 10 days the spill jet sometimes cannot be distinguished in the velocity field from surface eddies or from the dso the vorticity structure of the jet confirms its unstable nature with peak relative and tilting vorticity terms reaching twice the planetary vorticity term the

relationships between tectonic and geomorphological linear features in the guadix baza basin southern spain linear elements of the landscape of the guadix baza basin southern spain were identified from a landsat tm image three important lineament trends have been identified in the guadix baza basin the first is ne sw which is the dominant trend in the basin the second is nw se and the third is ene wsw these three trends are correlated to the major faults of the guadix baza basin the study of linear features by the analysis of satellite data has revealed a strong link between the buried tectonic structures and the morphological features appearing at the surface the distribution and density of lineaments explains much of the morphology of the land surface it is possible to reconstruct elements of the tectonic and denudational history of the region and show that during quaternary times lineaments controlled the sedimentation of the basin and the drainage pattern copyright 1999 john wiley sons ltd

hydrologic response of the greenland ice sheet the role of oceanographic warming the response of the greenland ice sheet to ongoing climate change remains an area of great uncertainty with most previous studies having concentrated on the contribution of the atmosphere to the ice mass balance signature here we systematically assess for the first time the influence of oceanographic changes on the ice sheet the first part of this assessment involves a statistical analysis and interpretation of the relative changes and variations in sea surface temperatures ssts and air temperatures around greenland for the period 1870 2007 this analysis is based on hadisst1 and reynolds oi v2 sst analyses in situ sst and deeper ocean temperature series surface air temperature records for key points located around the greenland coast and examination of atmospheric pressure and geopotential height from ncep ncar reanalysis second we carried out a novel sensitivity experiment in which ssts were perturbed as input to a regional climate model and document the resulting effects on simulated greenland climate and surface mass balance we conclude that sea surface ocean temperature forcing is not sufficient to strongly influence precipitation snow accumulation and melt runoff of the ice sheet additional evidence from meteorological reanalysis suggests that high greenland melt anomalies of summer 2007 are likely to have been primarily forced by anomalous advection of warm air masses over the ice sheet and to have therefore had a more remote atmospheric origin however there is a striking correspondence between ocean warming and dramatic accelerations and retreats of key greenland outlet glaciers in both southeast and southwest greenland during the late 1990s and early 2000s copyright 2008 john wiley sons ltd

active transfer fault zone linking a segmented extensional system betics southern spain insight into heterogeneous extension driven by edge delamination pliocene and quaternary tectonic structures mainly consisting of segmented northwest southeast normal faults and associated seismicity in the central betics do not agree with the transpressive tectonic nature of the africa eurasia plate boundary in the ibero maghrebian region active extensional deformation here is heterogeneous individual segmented normal faults being linked by relay ramps and transfer faults including oblique slip and both dextral and sinistral strike slip faults normal faults extend the hanging wall of an extensional detachment that is the active segment of a complex system of successive wsw directed extensional detachments which have thinned the betic upper crust since middle miocene two areas which are connected by an active 40 km long dextral strike slip transfer fault zone concentrate present day extension both the seismicity distribution and focal mechanisms agree with the position and regime of the observed faults the activity of the transfer zone during middle miocene to present implies a mode of extension which must have remained substantially the same over the entire period thus the mechanisms driving extension should still be operating both the westward migration of the extensional loci and the high asymmetry of the extensional systems can be related to edge delamination below the south iberian margin coupled with roll back under the alboran sea involving the asymmetric westward inflow of asthenospheric material under the margins

paleomagntism of archean rocks from northwestern ontario ii shelley lake granite quetico subprovince the 2580 20 ma shelley lake granite of the quetico gneiss belt in northwestern ontario preserves two distinct natural remanent magnetizations nrm s of different ages type 1 nrm of either normal 1n or reverse 1r polarity was isolated in 43 samples using three methods stable end point directions orthogonal vector plots and converging remagnetization circles the mean direction based on both 1n and 1r results is d 5 9 i 56 4 k 95 4 95 4 4 n 12 sites which is significantly different from both the present earth s field pef and axial dipole field directions at the site type 2 nrm either normal 2n or reverse 2r was successfully separated from 1n 1r in 13 samples its mean direction combining both polarities is d 70 3 i 27 8 k 20 1 95 9 4 n 13 samples the paleopole sl1 corresponding to 1n 1r falls at 65 8 e 77 6 n near track 6 of the laurentian apparent polar wander path apwp around 2600 ma this remanence is carried principally by primary multido

effect of near terminus subglacial hydrology on tidewater glacier submarine melt rates submarine melting of greenlandic tidewater glacier termini is proposed as a possible mechanism driving their recent thinning and retreat we use a general circulation model mitgcm to simulate water circulation driven by subglacial discharge at the terminus of an idealized tidewater glacier we vary the spatial distribution of subglacial discharge emerging at the grounding line of the glacier and examine the effect on submarine melt volume and distribution we find that subglacial hydrology exerts an important control on submarine melting under certain conditions a distributed system can induce a factor 5 more melt than a channelized system with plumes from a single channel inducing melt over only a localized area subglacial hydrology also controls the spatial distribution of melt which has the potential to control terminus morphology and calving style our results highlight the need to constrain near terminus subglacial hydrology at tidewater glaciers if we are to represent ocean forcing accurately

a step fault in central betics associated with lateral lithospheric tearing at the northern edge of the gibraltar arc subduction system abstract we study the crustal and lithospheric mantle structure under central betics in the westernmost mediterranean region by migrating p receiver functions along a dense seismic profile 2 km interstation distance the profile north south oriented probes the crustal structure of different geological units from the alboran domain in the south with metamorphic rocks through the external zones with sedimentary rocks to the variscan terrains of the iberian massif in the north from north to south the moho depth increases from 30 km to 46 km underneath the guadix basin due to the underthrusting of the iberian crust below the alboran crust and suddenly shallows to 30 km underneath the internal zones with a step of 17 km this sharp moho step correlates well with a lithospheric step of 40 km where the thickness of the lithosphere changes abruptly from 100 km in the north to 50 km in the south we interpret this sharp and prominent lithospheric step as the termination of the iberian lithosphere caused by a near vertical step subduction transform edge propagator fault that continues towards the surface as a positive flower tectonic structure of crustal scale this step fault is located at the northern edge of the narrow westernmost mediterranean subduction system facilitating the slab rollback motion towards the west the sharp termination of the iberian lithosphere occurs under the contact between the alpujarride and the nevado filabride complexes of the alboran domain in an ene wsw right lateral transpressive shear zone the thickest crust and lithosphere do not correlate with the highest topography along the profile suggesting that this high topography is a combined effect of the positive flower structure and the push up of the asthenosphere produced by the removal of the iberian lithosphere

modeling ice shelf cavities in a z coordinate ocean general circulation model 1 processes at the ice shelf ocean interface and in particular in ice shelf cavities around antarctica have an observable effect on the solutions of basin scale to global coupled ice ocean models despite this these processes are not routinely represented in global ocean and climate models it is shown that a new ice shelf cavity model for z coordinate models can reproduce results from an intercomparison project of earlier approaches with vertical or isopycnic coordinates as a proof of concept ice shelves are incorporated in a 100 year global integration of a z coordinate model in this simulation glacial meltwater can be traced as far as north as 15 s the observed effects of processes in the ice shelf cavities agree with previous results from a coordinate model notably the increase in sea ice thickness however melt rates are overestimated probably because the parameterization of basal melting does not suit the low resolution of this configuration

early middle miocene stratigraphic turning points in the alicante region se spain reflections of western mediterranean plate tectonic reorganizations abstract the paper concerns the miocene deposits of the alicante region se spain which forms part of the prebetic and intermediate units representing the former southern passive margin of the iberian continent from the late jurassic up to the miocene the alicante region was the scene of a facies distribution with more continental lagoonal or shallow marine conditions in the north and northwest and more open or deeper marine in the south and southeast the early middle miocene deposits can be divided in three sedimentary cycles each one controlled by a different tectonic regime cycle i aquitanian is deposits after a block faulting phase at about 25 ma related to the formation of the ligurian and balearic troughs cycle ii burdigalian early langhian is separated from first cycle sediments by a complete reorientation of palaeogeography at 19 5 ma due to the collision of iberia with africa the southern part of the region is folded and uplifted and separated from a northern emerged area by a trough cycle iii late langhian serravallian is controlled by strike slip movements caused by the continuing convergence between africa and europe and resulting in the development of a new set of basins at 15 5 ma at the middle late miocene boundary the alicante region emerges thus younger important tectonics could not be dated our results are in conflict with several recent plate tectonic models for the miocene history of the western mediterranean where the internal betic zone is placed juxtaposed to the alicante region prior to the burdigalian

chemical evolution of groundwater in triassic gypsum bearing carbonate aquifers las alpujarras southern spain a hydrochemical study employing modelling techniques was carried out using samples taken at 65 points springs and wells in triassic carbonate aquifers lujar gador unit alpujarride complex betic cordillera these aquifers are made up of limestones and dolomites with some gypsum scattered or interbedded though the area is semi arid recharge is relatively high because of their mountainous nature the carbonate rocks contain dense microfissuration the groundwater flow regime is predominantly diffuse the karstic forms are in general poorly developed two main hydrochemical processes have been identified in these aquifers one is incongruent dissolution of dolomite that determines the chemical composition of the less mineralised water the other is dedolomitisation dolomite dissolution together with calcite precipitation caused by dissolution of gypsum which becomes predominant when the flow encounters interbedded gypsum this reaction is also frequently associated with low temperature thermalism and can play a part in more intense local karstification cavities sinkholes high transmisivity in wells observed in the sectors of these aquifers where gypsum is more abundant a reaction path model has been used to simulate the geochemical processes through a hypothetical aquifer with similar lithology to the alpujarride carbonate aquifers successive stages of evolution through the carbonate sequence represented by different saturation states with respect to calcite dolomite gypsum and co2 have been modelled and then compared with the field data

u pb zircon and monazite ages from the kapuskasing uplift age constraints on deformation within the ivanhoe lake fault zone a decade of u pb dating of zircon and monazite from high grade metamorphic rocks in the kapuskasing uplift has identified a series of magmatic and metamorphic events between 2700 and 2585 ma and indicates that the onset of regional granulite metamorphism took place at mid crustal levels of the southern superior craton ca 2660 ma new u pb ages for zircon and monazite have been used to constrain the age of ductile deformation fabrics at two sites in the ivanhoe lake fault zone the structure along which the granulite facies kapuskasing structural zone was uplifted these results suggest that the fault zone was probably active in the late archean as young as 2630 ma and again at approximately 2500 ma

spreading of warm ocean waters around greenland as a possible cause for glacier acceleration we examine the pattern of spreading of warm subtropical origin waters around greenland for the years 1992 2009 using a high resolution 4km horizontal grid coupled ocean and sea ice simulation the simulation provided by the estimating the circulation and climate of the ocean phase ii ecco2 project qualitatively reproduces the observed warming of subsurface waters in the subpolar gyre associated with changes of the north atlantic atmospheric state that occurred in the mid 1990s the modeled subsurface ocean temperature warmed by 1 5 c in southeast and southwest greenland during 1994 2005 and subsequently cooled by 0 5 c modeled subsurface ocean temperature increased by 2 2 5 c in central and then northwest greenland during 1997 2005 and stabilized thereafter while it increased after 2005 by xu and others 2012 we show that the oceanic changes have very likely increased the subaqueous melt rates of the glacier fronts and in turn impacted the rates of glacier flow

undercutting of marine terminating glaciers in west greenland marine terminating glaciers control most of greenland s ice discharge into the ocean but little is known about the geometry of their frontal regions here we use side looking multibeam echo sounding observations to reveal that their frontal ice cliffs are grounded deeper below sea level than previously measured and their ice faces are neither vertical nor smooth but often undercut by the ocean and rough deep glacier grounding enables contact with subsurface warm salty atlantic waters aw which melts ice at rates of meters per day we detect cavities undercutting the base of the calving faces at the sites of subglacial water sgw discharge predicted by a hydrological model the observed pattern of undercutting is consistent with numerical simulations of ice melt in which buoyant plumes of sgw transport warm aw to the ice faces glacier undercutting likely enhances iceberg calving impacting ice front stability and in turn the glacier mass balance

numerical experiments on subaqueous melting of greenland tidewater glaciers in response to ocean warming and enhanced subglacial discharge the largest dischargers of ice in greenland are glaciers that terminate in the ocean and melt in contact with sea water studies of ice sheet ocean interactions have mostly focused on melting beneath near horizontal floating ice shelves for tidewater glaciers melting instead takes place along the vertical face of the calving front here we modify the massachusetts institute of technology general circulation model mitgcm to include ice melting from a calving face with the freshwater outflow at the glacier grounding line we use the model to predict melt rates and their sensitivity to ocean thermal forcing and to subglacial discharge we find that melt rates increase with approximately the one third power of the subglacial water flux and increase linearly with ocean thermal forcing our simulations indicate that consistent with limited field data melting ceases when subglacial discharge is shut off and reaches several meters per day when subglacial discharge is high in the summer these results are a first step toward a more realistic representation of subglacial discharge and of ocean thermal forcing on the subaqueous melting of tidewater glaciers in a numerical ocean model our results illustrate that the ice front melting process is both complex and strongly time dependent

seasonal variability of submarine melt rate and circulation in an east greenland fjord 1 the circulation in a glacial fjord driven by a large tidewater glacier is investigated using a nonhydrostatic ocean general circulation model with a melt rate parameterization at the vertical glacier front the model configuration and water properties are based on data collected in sermilik fjord near helheim glacier a major greenland outlet glacier the approximately two layer stratification of the fjord s ambient waters causes the meltwater plume at the glacier front to drive a double cell circulation with two distinct outflows one at the free surface and one at the layers interface in summer the discharge of surface runoff at the base of the glacier subglacial discharge causes the circulation to be much more vigorous and associated with a larger melt rate than in winter the simulated double cell circulation is consistent in both seasons with observations from sermilik fjord seasonal differences are also present in the vertical structure of the melt rate which is maximum at the base of the glacier in summer and at the layers interface in winter simulated submarine melt rates are strongly sensitive to the amount of subglacial discharge to changes in water temperature and to the height of the layers they are also consistent with those inferred from simplified one dimensional models based on the theory of buoyant plumes our results also indicate that to correctly represent the dynamics of the meltwater plume care must be taken in the choice of viscosity and diffusivity values in the model

externally forced fluctuations in ocean temperature at greenland glaciers in non summer months the factors that control the submarine melt rate at greenland s glaciers are uncertain and largely inferred from brief summer surveys in the fjords where glaciers terminate continuous records of water properties and velocity for the months september to may from two large greenland fjords reveal strong variability on 3 to 10 day timescales as a result of pulses of water that are propagated from the shelf ocean

alpine tectonics and rotation pole evolution of iberia abstract the geological evolution of the betic cordilleras and pyrenees reflects the cretaceous and tertiary rotation pole and kinematic evolution of the iberian and african plates new constraints on the alpine tectonic evolution of the iberian plate are provided by p t t data and regionally consistent stretching lineations from the metamorphic parts of the betic cordilleras high pressure low temperature metamorphism in the betic cordilleras resulted from continent continent collision which caused subduction to a maximum depth of 37 km a preliminary 116 10 ma radiometric age for this event corresponds to the initiation of seafloor spreading to the west of iberia which lasted until about 80 ma intracontinental thrusting in the betics between 99 ma and 83 ma took place after subduction ended e w to ese wnw trending stretching lineations indicate the direction of thrusting which resulted in extensional strains of 200 600 the timing of thrusting in the betics coincides with a 95 80 ma tectonic phase in northern africa during which e w stretching lineations were formed the stretching lineations are coincident with the 110 80 ma motion vector of africa iberia with respect to eurasia thrusting in the betics and deformation in northern africa was driven by convergence of africa iberia and eurasia cretaceous deformation is further recorded by terrigeneous sedimentation in the mauritanian flysch and by the tectosedimentary evolution of the malaguide complex crustal thinning magmatism and metamorphism in the pyrenees during the 110 85 ma period is governed by a left lateral strike slip of africa iberia with respect to eurasia around the same rotation pole as thrusting in the betics during the 80 54 ma period the rotation pole was situated west of gibraltar near the previous active collision zone this inhibited large scale overthrusting and related penetrative deformation in northern africa and the betic cordilleras deformation was instead transferred to the northern boundary of iberia now acting as an african promontory from the campanian on wards oblique convergence took place around the combined gibraltar rotation pole deformation culminated in the late eocene corresponding to spreading in the norwegian greenland sea at 55 ma which induced an additional compression in western eurasia during the pyrenean collision high pressure metamorphic rocks in the betic cordilleras were exhumed and they cooled substantially the cooling trend was disturbed by oligocene extensional deformation and introduction of a transient heat source which correlates with the mantle being uplifted during extension heating culminated at the oligocene miocene boundary in the betic cordilleras and in northern africa this evolution agrees with the development of a plate boundary between iberia and africa at 30 ma after completion of the pyrenean collision the new plate boundary was connected to the western european rift system renewal of compression and overthrusting in the betic zone took place after 20 ma overthrusting is succeeded by two phases of wrenching juxtaposing crustal segments with different moho depths inherited from the late oligocene to early miocene extension

subglacial discharge driven renewal of tidewater glacier fjords the classic model of fjord renewal is complicated by tidewater glacier fjords where submarine melt and subglacial discharge provide substantial buoyancy forcing at depth here we use a suite of idealized high resolution numerical ocean simulations to investigate how fjord circulation driven by subglacial plumes tides and wind stress depends on fjord width grounding line depth and sill height we find that the depth of the grounding line compared to the sill is a primary control on plume driven renewal of basin waters in wide fjords the plume exhibits strong lateral recirculation increasing the dilution and residence time of glacially modified waters rapid drawdown of basin waters by the subglacial plume in narrow fjords allows for shelf waters to cascade deep into the basin wide fjords result in a thin boundary current of shelf waters that flow toward the terminus slightly below sill depth wind forcing amplifies the plume driven exchange flow however wind induced vertical mixing is limited to near surface waters tidal mixing over the sill increases in fjord transport of deep shelf waters and erodes basin stratification above the sill depth these results underscore the first order importances of fjord glacier geometry in controlling circulation in tidewater glacier fjords and thus ocean heat transport to the ice

impact of periodic intermediary flows on submarine melting of a greenland glacier the submarine melting of a vertical glacier front induced by an intermediary circulation forced by periodic density variations at the mouth of a fjord is investigated using a nonhydrostatic ocean general circulation model and idealized laboratory experiments the idealized configurations broadly match that of sermilik fjord southeast greenland a largely two layers system characterized by strong seasonal variability of subglacial discharge consistent with observations the numerical results suggest that the intermediary circulation is an effective mechanism for the advection of shelf anomalies inside the fjord in the numerical simulations the advection mechanism is a density intrusion with a velocity which is an order of magnitude larger than the velocities associated with a glacier driven circulation in summer submarine melting is mostly influenced by the discharge of surface runoff at the base of the glacier and the intermediary circulation induces small changes in submarine melting in winter on the other hand submarine melting depends only on the water properties and velocity distribution at the glacier front hence the properties of the waters advected by the intermediary circulation to the glacier front are found to be the primary control of the submarine melting when the density of the intrusion is intermediate between those found in the fjord s two layers there is a significant reduction in submarine melting on the other hand when the density is close to that of the bottom layer only a slight reduction in submarine melting is observed the numerical results compare favorably to idealized laboratory experiments with a similar setup