assessing the reliability of magnesium in foraminiferal calcite as a proxy for water mass temperatures though many studies on the mg contents in the calcitic tests of foraminifers exist the processes controlling its uptake are still a matter of debate laboratory cultures offer an excellent opportunity to reveal these mechanisms the mg concentrations within single chambers of the planktic foraminifer globigerinoides sacculifer brady maintained under controlled laboratory conditions were measured 1 at variable temperatures 19 5 29 5 c and constant salinity and 2 at variable salinity 22 45 and constant temperature the experimental results suggest that under natural conditions temperature is the leading mechanism controlling the mg ca ratio temperature and magnesium are related proportionally a temperature increase of ca 10 c gives rise to an increase of the magnesium concentrations of ca 130 drastic unnatural salinity changes dominate the effects of temperature a 110 change in the mg ca ratio was observed when salinity was elevated or reduced by more than ca 10 specimens which underwent gametogenesis reveal significantly higher mg concentrations than specimens that did not release gametes partition coefficients for mg in foraminiferal calcite are orders of magnitude lower than values from inorganically precipitated calcite when comparing observed mg ca ratios of foraminiferal tests with predicted mg ca ratios calculated according to empirical equations it becomes evident that foraminiferal tests are undersaturated with respect to mg for the water temperature they have experienced apparently foraminifers are capable of controlling their mg concentration the physiological processes presumably responsible for such depressed mg ca ratios appear to be temperature controlled as deduced from the close relationship of the observed mg ca ratios and water temperature this study demonstrates that variations in temperature and salinity are definitely reflected in the mg content of foraminiferal tests magnesium may thus serve as a paleo proxy for past surface water temperatures as long as postdepositional changes and salinity variations are of subordinate importance or can be excluded

the preparatory phase of the mw 6 1 2009 l aquila italy normal faulting earthquake traced by foreshock time lapse tomography

inter hemispheric asymmetry in the early pleistocene pacific warm pool the position of the southern boundary of the pacific warm pool is shown to have been stable since the early pleistocene based upon a planktic foraminiferal mg ca derived reconstruction of subtropical sea surface temperature in the coral sea this contrasts with previous reconstructions showing warm pool contraction from the north and east and means that the early pleistocene warm pool was more hemispherically asymmetric than its present configuration the latter was not established until 1ma supporting a strengthening of the northern hadley cell which was not replicated in its southern counterpart prior to the mid pleistocene transition copyright 2010 by the american geophysical union

the effects of temperature salinity and the carbonate system on mg ca in globigerinoides ruber white a global sediment trap calibration abstract the mg ca of planktic foraminifera globigerinoides ruber white is a widely applied proxy for tropical and sub tropical sea surface temperature the accuracy with which temperature can be reconstructed depends on how accurately relationships between mg ca and temperature and the multiple secondary controls on mg ca are known however these relationships remain poorly quantified under oceanic conditions here we present new calibrations based on 440 sediment trap plankton tow samples from the atlantic pacific and indian oceans including 130 new samples from the bay of bengal arabian sea and the tropical atlantic ocean our results indicate temperature salinity and the carbonate system all significantly influence mg ca in g ruber white we propose two calibration models the first model assumes ph is the controlling carbonate system parameter in this model mg ca has a temperature sensitivity of 6 0 0 8 c 2 a salinity sensitivity of 3 3 2 2 psu and a ph sensitivity of 8 3 7 7 0 1 ph units the second model assumes carbonate ion concentration co 3 2 is the controlling carbonate system parameter in this model mg ca has a temperature sensitivity of 6 7 0 8 c a salinity sensitivity of 5 0 3 0 psu and a co 3 2 sensitivity of 0 24 0 11 mol kg 1 in both models the temperature sensitivity is significantly lower than the widely applied sensitivity of 9 0 0 6 c application of our new calibrations to down core data from the last glacial maximum considering whole ocean changes in salinity and carbonate chemistry indicate a cooling of 2 4 1 6 c in the tropical oceans if ph is the controlling parameter and 1 5 1 4 c if co 3 2 is the controlling parameter

surface and subsurface seawater temperature reconstruction using mg ca microanalysis of planktonic foraminifera globigerinoides ruber globigerinoides sacculifer and pulleniatina obliquiloculata laser ablation inductively coupled plasma mass spectrometry microanalyses of mg ca across individual final chambers of three planktonic foraminifera species globigerinoides ruber g sacculifer and pulleniatina obliquiloculata reveal significant interspecies differences in test mg concentrations whereas these three species have similar mg ca values at low sea surface temperatures similar to 22 degrees c they diverge markedly at high sea surface temperatures similar to 29 degrees c explanations for these differences in species mg ca values based on detailed comparison of species intratest mg ca distributions suggest that compositional variability within tests cannot account for the observed deviation of species mg ca values in warm water equatorial regions multiple regression modeling and delta o 18 analysis of globigerinoides sacculifer tests indicate that interspecies differences in mg ca values result from different depth habitats the average mg ca values of g ruber final chambers reflect the temperature of the surface mixed layer 0 25 m whereas those of g sacculifer and pulleniatina obliquiloculata correlate best with subsurface temperatures at 50 75 m and 100 125 m water depths respectively mg ca calibration to the temperatures at these depths reveals a similar temperature control on mg test composition in all species combining our results with mg ca values from published culturing experiments we derive a generalized equation for the effect of temperature and seawater salinity on foraminiferal mg ca we also show that the mg ca composition of specific calcite layers within foraminiferal tests including the low mg ca layers of globigerinoides ruber and g sacculifer and the cortex layer of pulleniatina obliquiloculata correlates with seawater temperature and can be used as an additional proxy for seawater temperature

a study of cleaning procedures used for foraminiferal mg ca paleothermometry the various cleaning steps required for preparation of foraminiferal samples for mg ca and sr ca analysis are evaluated for their relative importance and effects on measured elemental ratios it is shown that the removal of silicate contamination is the most important step for the measurement of mg ca ratios in an example bulk sample mg ca decreases from 10 5 to 2 5 mmol mol 1 during clay removal oxidation of organic material causes a lowering of sample mg ca in the order of 10 or approximately 1 c when converted to temperature use of dilute acid leaching to remove adsorbed contaminants causes partial dissolution of the sample carbonate and a corresponding decrease in mg ca reductive treatment also causes dissolution of the sample and a decrease in the mg ca ratio of up to 10 15 sample preparation for sr ca analysis does not require the same degree of rigor as is necessary for mg ca work the within run reproducibility of the method described here for g ruber in a core top sample from the arabian sea was 1 8 mean sample ratio was 4 72 mmol mol 1 when converted to temperature this becomes 28 0 2 c the equivalent result for sr ca was 0 5 mean ratio 1 44 mmol mol 1

evaluating models of coulomb stress transfer is variable fault geometry important to determine the importance of receiver fault geometry in coulomb stress calculations a new methodology is presented to model faults with variable geometry although most models use planar faults it is known that these are inaccurate representations of faults observed in the field the central italian apennines are chosen as a straightforward tectonic system with well exposed normal faults to investigate the effect of variable geometry it is shown that the static coulomb stress transfer is most sensitive to changes in strike of the receiver faults rather than changes in dip and rake therefore a novel methodology to generate strike variable faults composed of discrete rectangular patches is developed using the 2009 l aquila earthquake mw 6 3 the calculated stress transferred to planar versus variable faults is assessed the stress transferred to variable faults is sufficiently different when compared to planar cases to merit other earthquake sequences being reassessed with available fault geometry

hydraulic tests in highly permeable aquifers 1 a semianalytical solution is presented for a mathematical model describing the flow of groundwater in response to a slug or pumping test in a highly permeable confined aquifer this solution which is appropriate for wells of any degree of penetration and incorporates inertial mechanisms at both the test and observation wells can be used to gain new insights into hydraulic tests in highly permeable settings the oscillatory character of slug and pumping induced responses will vary considerably across a site even in an essentially homogeneous formation when wells of different radii depths and screen lengths are used thus variations in the oscillatory character of responses do not necessarily indicate variations in hydraulic conductivity k existing models for slug tests in partially penetrating wells in high k aquifers neglect the storage properties of the media that assumption however appears reasonable for a wide range of common conditions unlike in less permeable formations drawdown at an observation well in a high k aquifer will be affected by head losses in the pumping well those losses which affect the form of the pumping induced oscillations can be difficult to characterize thus analyses of observation well drawdown should utilize data from the period after the oscillations have dissipated whenever possible although inertial mechanisms can have a large impact on early time drawdown that impact decreases rapidly with duration of pumping and distance to the observation well conventional methods that do not consider inertial mechanisms should therefore be viable options for the analysis of drawdown data at moderate to large times

the dynamics of extensional sedimentary basins constraints from subsidence inversion on the continents sedimentary basins are generally formed by small amounts of lithospheric extension extension might cease because the lithospheric mantle has cooled and strengthened or because the driving force is removed in the former case a relationship should exist between the maximum strain rate during extension and the final stretching factor attained we explore how this relationship depends on the rheology of the lithospheric mantle and of the crust as well as on sedimentation and prior rifting events we also present strain rate information obtained by inverting subsidence data from a variety of sedimentary basins there is evidence of a systematic relationship between strain rate and stretching factor in each basin implying that lithospheric rheology is consistent with the rheology of olivine measured in laboratory experiments our data are difficult to explain if removal of the driving force governs the magnitude of stretching factors

indo pacific warm pool variability during the holocene and last glacial maximum we measured oxygen isotopes and mg ca ratios in the surface dwelling planktonic foraminifer globigerinoides ruber white s s and the thermocline dweller pulleniatina obliquiloculata to investigate upper ocean spatial variability in the indo pacific warm pool ipwp we focused on three critical time intervals the last glacial maximum lgm 18 21 5 ka the early holocene 8 9 ka and the late holocene 0 2 ka our records from 24 stations in the south china sea timor sea indonesian seas and western pacific indicate overall dry and cool conditions in the ipwp during the lgm with a low thermal gradient between surface and thermocline waters during the early holocene sea surface temperatures increased by similar to 3 degrees c over the entire region indicating intensification of the ipwp however in the eastern indian ocean timor sea the thermocline gradually shoaled from the lgm to early holocene reflecting intensification of the subsurface indonesian throughflow itf increased surface salinity in the south china sea during the holocene appears related to northward displacement of the monsoonal rain belt over the asian continent together with enhanced influx of saltier pacific surface water through the luzon strait and freshwater export through the java sea opening of the freshwater portal through the java sea in the early holocene led to a change in the vertical structure of the itf from surface to thermocline dominated flow and to substantial freshening of timor sea thermocline waters

fault slip rate variations during crustal scale strain localisation central italy rates of plate motion are generally uniform over 10 102 myrs timescales faults between tectonic plates might therefore be expected to show temporally uniform slip rates if the same number of faults remain active for an extending region of the eurasia africa plate boundary italy finite throw values vertical component of the slip for seismogenic normal faults are less than that predicted when recent throw rates are extrapolated over the fault lifetimes the effect correlates with distance from the fault system tips and demonstrates that the slip rates on centrally located faults have increased with time neighbouring normal faults were active in the quaternary but show no signs of surface faulting during the latest pleistocene to holocene death of these faults has provided the extra strain per unit time to drive the increased slip rates measured on other faults thus fault interaction and death modify slip rates and seismic hazards associated with plate tectonics

active normal faulting during the 1997 seismic sequence in colfiorito umbria did slip propagate to the surface in order to determine whether slip during an earthquake on the 26th september 1997 propagated to the surface structural data have been collected along a bedrock fault scarp in umbria italy these collected data are used to investigate the relationship between the throw associated with a debated surface rupture observed as a pale unweathered stripe at the base of the bedrock fault scarp and the strike dip and slip vector previous studies have suggested that the surface rupture was produced either by primary surface slip or secondary compaction of hangingwall sediments some authors favour the latter because sparse surface fault dip measurements do not match nodal plane dips at depth it is demonstrated herein that the strike dip and height of the surface rupture represented by a pale unweathered stripe at the base of the bedrock scarp shows a systematic relationship with respect to the geometry and kinematics of faulting in the bedrock the strike and dip co vary and the throw is greatest where the strike is oblique to the slip vector azimuth where the highest dip values are recorded this implies that the throw values vary to accommodate spatial variation in the strike and dip of the fault across fault plane corrugations a feature that is predicted by theory describing conservation of strain along faults but not by compaction furthermore published earthquake locations and reported fault dips are consistent with the analysed surface scarps when natural variation for surface dips and uncertainty for nodal plane dips at depth are taken into account this implies that the fresh stripe is indeed a primary coseismic surface rupture whose slip is connected to the seismogenic fault at depth we discuss how this knowledge of the locations and geometry of the active faults can be used as an input for seismic hazard assessment

late quaternary to decadal velocity fields in asia 1 fields of crustal velocity and strain rate within asia averaged over horizontal distances of 300 km are calculated from estimates of quaternary slip rates on faults and rates of change of lengths of baselines between gps sites the calculated fields fit strain rate components estimated from quaternary slip rates within 95 confidence limits and fit the gps data with an rms residual of 2 5 mm yr 1 the strain rate field constrained only by quaternary slip rates of faults differs from the combined solution at the level of 20 nstrain yr 1 and the differences are explicable by the limited accuracy of geological estimates of slip rate therefore the strain rate fields determined by geodetic measurements taken on the 10 year timescale are consistent with geological observations on the 104 year timescale the combined solution for velocities shows plate or block like motion within deforming asia only in tarim south china and the amurian region elsewhere the kinematics of rigid blocks does not provide a useful description of the motion in particular velocities relative to eurasia point at high angles to contours of their magnitudes not parallel to them as they would if large regions moved as rigid blocks the axes of principal horizontal compressional strain align with topographic gradients in agreement with previous suggestions that asia deforms as a continuum under the influence of gravity

reconstructing the stable isotope geochemistry and paleotemperatures of the equatorial atlantic during the last 150 000 years results from individual foraminifera this study represents an attempt to extract paleoclimatic data from the deep sea record by analyzing foraminiferal shells individually using the oxygen 18o and carbon 13c isotopic composition of individual orbulina universa and neogloboquadrina dutertrei we present an approach to reconstruct the 18o of seawater 18ow the 13c of co2 and seasonal maximum sea surface temperatures sst in the western and eastern equatorial atlantic we examine the glacial and interglacial extremes of the last 150 000 years isotope stages 1 2 5e and 6 comparison of recent water column hydrography with reconstructions from core top assemblages shows that o universa and n dutertrei 18o and 13c values accurately record hydrographic conditions in the mixed layer and upper thermocline at both sites by analyzing shells individually we can evaluate the effect of bioturbation on the range of 18o and 13c values in each interval and take it into consideration in our data interpretations downcore results show that n dutertrei 18o values in the western equatorial atlantic reflect glacial to interglacial changes in 18ow due to continental ice formation 18o 1 30 we use changes in n dutertrei 18o values between core intervals to estimate the ice volume effect in paleotemperature calculations for the mixed layer to validate the use of o universa for mixed layer reconstructions we have added individual globigerinoides sacculifer data for stages 1 and 2 at both sites paleotemperature reconstructions from o universa 18o values indicate that maximum seasonal mixed layer temperatures in the equatorial atlantic decreased by at most 2 6 c between isotope stages 1 and 2 and by no more than 3 4 c between stages 1 and 6 individual shell data from g sacculifer yield similar results indicating that maximum o universa 18o values reflect the mixed layer environment in agreement with climate long range investigation mapping and prediction climap 1981 sst reconstructions for stage 2 these data indicate little change between glacial and interglacial paleotemperatures in the equatorial atlantic an electronic supplement of this material may be obtainedon a diskette or anonymous ftp from kosmos agu org login to agu s ftp account using anonymous as theusername and guest as the password go to the rightdirectory by typing cd apend type ls to see what files areavailable type get and the name of the file to get it finally type exit to leave the system paper 95pa03773 reconstructing the stable isotope geochemistry andpaleotemperatures of the equatorial atlantic during the last150 000 years results from individual foraminifera katharina billups and howard j spero diskette may beordered from american geophysical union 2000 floridaavenue n w washington dc 20009 15 00 paymentmust accompany order

hydrochemistry to delineate groundwater flow conditions in the mogher al mer area damascus basin southwestern syria the hydrochemistry of groundwater from the mogher al mer area located in southwestern syria has been used as a tool to identify and assess the hydrogeological systems and associated conditions in this arid region of syria groundwater is considered as the main source of water supply for both drinking and irrigation purposes the detailed description of hydrogeochemical conditions including major ions physico chemical and in situ field parameters has underlined the very complex variability of the stratigraphic sequences and hence the numerous hydrogeological units within the study area on the one hand groundwater chemical signature is found to be mainly controlled by the water rock interaction processes in the mountainous western part of the study area on the other hand anthropogenic influences are observed in the eastern plain in terms of recharge mechanisms the region can be considered as a part of a main intermediate or even regional flow system instead of a local one

short term vertical velocity field in the apennines italy revealed by geodetic levelling data we estimate current vertical movements along the apennines italy through repeatedly measured high precision levelling routes in order to highlight regional crustal deformation the analysis of a geodetic database with a minimum benchmark density of 0 7 bm km 1943 2003 time period is carried out we evaluate systematic and random error and their propagation along the levelling routes tests on original raw height data have been carried out to define error propagation the computed relative vertical rates stand significantly above error propagation a series of traverses along and across the apennines and a map of relative vertical velocities reveal a geodetic signal characterised by values up to 2 5 3 0 mm a and by wavelengths up to 100 km

mg ca ratios of two globigerinoides ruber white morphotypes implications for reconstructing past tropical subtropical surface water conditions 1 tests of the planktonic foraminifer globigerinoides ruber white d orbigny have become a standard tool for reconstructing past oceanic environments paleoceanographers often utilize the mg ca ratios of the foraminiferal tests for reconstructing low latitude ocean glacial interglacial changes in sea surface temperatures sst we report herein a comparison of mg ca measurements on sample pairs n 20 of two g ruber white morphotypes g ruber sensu stricto s s and g ruber sensu lato s l from surface and downcore samples of the western pacific and indian oceans g ruber s s refers to specimens with spherical chambers sitting symmetrically over previous sutures with a wide high arched aperture whereas g ruber s l refers to a more compact test with a diminutive final chamber and small aperture the g ruber s s specimens generally show significantly higher mg ca ratios compared to g ruber s l our results from the mg ca ratio analysis suggest that g ruber s l specimens precipitated their shells in slightly colder surface waters than g ruber s s specimens this conclusion is supported by the differences in 18o and 13c values between the two morphotypes although it is still unclear if these two morphotypes represent phenotypic variants or sibling species our findings seem to support the hypothesis of depth and or seasonal allopatry within a single morphospecies

salinity bias on the foraminifera mg ca thermometry correction procedure and implications for past ocean hydrographic reconstructions 1 mg ca in foraminiferal calcite has recently been extensively used to estimate past oceanic temperatures here we show however that the mg ca temperature relationship of the planktonic species globigerinoides ruber is significantly affected by seawater salinity with a 1 psu change in salinity resulting in a 1 6 c bias in mg ca temperature calculations if not accounted for such a bias could lead for instance to systematic overestimations of mg ca temperatures during glacial periods when global ocean salinity had significantly increased compared to today we present here a correction procedure to derive unbiased sea surface temperatures sst and 18osw from g ruber tmg ca and 18of measurements this correction procedure was applied to a sedimentary record to reconstruct hydrographic changes since the last glacial maximum lgm in the western pacific warm pool while uncorrected tmg ca data indicate a 3 c warming of the western pacific warm pool since the lgm the salinity corrected sst result in a stronger warming of 4 c

geomorphological paleontological and 87sr 86sr isotope analyses of early pleistocene paleoshorelines to define the uplift of central apennines italy abstract the eastern border of the middle valley of the tiber river is characterized by several plio pleistocene paleoshorelines which extend for about 100 km along the western margin of the central apennines italy we studied these paleoshorelines by the means of geological and paleontological analyses and new 87 sr 86 sr isotope analyses the youngest and uppermost paleoshorelines have been detected and mapped through detailed geologic and stratigraphic surveys which led to the recognition of nearshore deposits cliff breccias alignments of lithophaga borings fossil abrasion notches and wave cut platforms the altitude of these paleoshorelines decreases almost regularly in the nnw sse direction from 480 to 220 m a s l measurements of the 87 sr 86 sr isotope ratio have been conducted on corals and mollusks collected from sediments outcropping close to the paleoshorelines the isotopic dating results indicate numerical values that range between 0 70907 and 0 70910 all over the 100 km outcrop these results together with biostratigraphic data constrain the age of the youngest paleoshorelines to 1 65 1 50 ma these paleoshorelines are thus considered almost isochronous giving an estimated uplift rate of 0 34 0 17 0 03 mm a moving from nnw to sse shape length and continuity of the 100 km long observed movements indicate that the studied paleoshorelines are an important marker of the quaternary uplift of the central apennines

regional deformation and offshore crustal local faulting as combined processes to explain uplift through time constrained by investigating differentially uplifted late quaternary palaeoshorelines the foreland hyblean plateau se sicily

an intensity ratio calibration method for the accurate determination of mg ca and sr ca of marine carbonates by icp aes an inductively coupled plasma atomic emission spectroscopy icp aes method for the accurate and precise simultaneous measurement of the mg ca and sr ca content of carbonates was established while a precision of 0 3 1 standard deviation sd is easily obtainable for both mg ca and sr ca analysis a ca matrix effect complicates achieving similar levels of accuracy with conventional calibration procedures an alternative ratio calibration procedure is proposed which overcomes the ca matrix effects and ensures the accuracy of the mg ca and sr ca analysis of marine carbonates to 0 3 almost an order of magnitude better than conventional calibration methods the longer term precision is 0 1 if the batch run average values are corrected for longer term drift the method is suitable for analysis of foraminiferal calcite and coral aragonite and can easily be adjusted for the analysis of other carbonates or microsamples

controls on trace element sr mg compositions of carbonate cave waters implications for speleothem climatic records abstract at two caves clamouse s france and ernesto ne italy cave drip and pool waters were collected and sampled at intervals over a 2 3 year period mg ca and sr ca concentration ratios corrected for marine aerosols are compared with those of bedrocks and in some cases aqueous leachates of soils and weathered bedrocks cave waters do not lie along mixing lines between calcite and dolomite of bedrock carbonate but typically show enhanced and covarying mg ca and sr ca four factors are considered as controlling processes 1 the much faster dissolution rate of calcite than dolomite allows for the possibility of increase of mg ca if water rock contact times are increased during drier conditions a theoretical model is shown to be comparable to experimental leachates 2 prior calcite precipitation along a flow path is a powerful mechanism for generating enhanced and covarying mg ca and sr ca ratios this mechanism requires the solution to lose co 2 into pores or caverns 3 incongruent dolomite dissolution has only limited potential and is best regarded as two separate processes of dolomite dissolution and calcite precipitation 4 selective leaching of mg and sr with respect to ca is shown to be important in leachates from ernesto where it appears to be a phenomenon of calcite dissolution in general selective leaching can occur whenever ca is sequestered into precipitates due to freezing or drying of soils or if there is derivation of excess sr and mg from non carbonate species the ernesto cave has abundant water supply which in the main chamber is derived from a reservoir with year round constant p co 2 of around 10 2 4 and no evidence of calcite precipitation in the karst above the cave two distinct but overlying trends of enhanced and covarying mg ca and sr ca away from the locus of bedrock compositions are due to calcite precipitation within the cave and at a variable drip site due to enhanced selective leaching at slow drip rates mg enhancement in the first chamber is due to a more dolomitic bedrock and longer residence times the clamouse site has a less abundant water supply and presents geochemical evidence of prior calcite precipitation both in the cave and in overlying porous dolomite dedolomitized limestone bedrock initial p co 2 values as high as 10 1 are inferred experimental incubations of clamouse soils which generated enhanced p co 2 and precipitated caco 3 had compositions similar to the karst waters calcite precipitation is inferred to be enhanced in drier conditions hydrological controls on cave water chemistry imply that the trace element chemistry of speleothems may be interpretable in palaeohydrological terms drier conditions tends to promote not only longer mean residence times enhancing dolomite dissolution and hence mg ca but also enhances degassing and calcite precipitation leading to increased mg ca and sr ca

evidence for localized active extension in the central apennines italy from global positioning system observations to assess how contemporary crustal extension is accommodated in the central apennines we use a new continuous and survey style global positioning system velocity solution and model the velocity field using a bicubic spline interpolation method the partitioning of contemporary deformation over the 100 km wide central apennines belt reveals a pattern of strain accumulation that largely reflects the spatial distribution of historic and recent seismicity the highest gradients of horizontal velocities are observed across those faults associated with m 6 historical earthquakes dislocation modeling shows that interseismic elastic loading in which creep occurs below the seismogenic upper crust on the downdip extensions of historically active faults reproduces the observed velocity gradients the current resolution level of quaternary fault slip rates estimates hinders the comparison with past deformation patterns and in particular the discrimination between 1 migrating episodes of short term focused activity 2 a distributed pattern of simultaneous deformation on parallel fault systems or 3 long term localization of active extension taking into account geomorphological evidence we propose that the geodetically observed deformation spatially corresponds with a long term localization of strain along the long wavelength 100 km topographic bulge caused by its highest gravitation potential energy relative to surrounding lowlands

amplitude and frequency modulations of the earth s obliquity for the last million years the variability of the earth s obliquity is a result of the deviation of the obliquity from its main component at 41 kyr and is generated by amplitude and frequency modulation for the last million years the amplitude modulation of the obliquity explains 8 of the obliquity s total variance and the frequency modulation explains 10 3 the spectra of both the amplitude and frequency modulations display significant power at 171 and 97 kyr the contribution of these two modulations to the variance of the insolation is evaluated at 65 degreesn in june the amplitude modulation of the obliquity explains 1 3 of the variance of the insolation and the frequency modulation explains 1 6 it is shown that the obliquity s frequency modulation is physically questionable and could only be meaningful for its components at 41 54 and 29 kyr taken separately

incorporation and preservation of mg in globigerinoides sacculifer implications for reconstructing the temperature and 18o 16o of seawater using bathymetric transects of surface sediments underlying similar sea surface temperatures but exposed to increasing dissolution we examined the processes which affect the relationship between foraminiferal mg ca and 18o we found that globigerinoides saccculifer calcifies over a relatively large range of water depth and that this is apparent in their mg content on the seafloor foraminiferal mg ca is substantially altered by dissolution with the degree of alteration increasing with water depth selective dissolution of the chamber calcite formed in surface waters shifts the shell s bulk mg ca and 18o toward the chemistries of the secondary crust acquired in colder thermocline waters the magnitude of this shift depends on both the range of temperatures over which the shell calcified and the degree to which it is subsequently dissolved in spite of this shift the initial relationship between mg ca and 18o determined by their temperature dependence is maintained we conclude that paired measurements of 18o and mg ca can be used for reconstructing 18owater though care must be taken to determine where in the water column the reconstruction applies

the 2009 l aquila central italy mw6 3 earthquake main shock and aftershocks 1 a m w 6 3 earthquake struck on april 6 2009 the abruzzi region central italy producing vast damage in the l aquila town and surroundings in this paper we present the location and geometry of the fault system as obtained by the analysis of main shock and aftershocks recorded by permanent and temporary networks the distribution of aftershocks 712 selected events with m l 2 3 and 20 with m l 4 0 defines a complex 40 km long nw trending extensional structure the main shock fault segment extends for 15 18 km and dips at 45 to the sw between 10 and 2 km depth the extent of aftershocks coincides with the surface trace of the paganica fault a poorly known normal fault that after the event has been quoted to accommodate the extension of the area we observe a migration of seismicity to the north on an echelon fault that can rupture in future large earthquakes

networking of shear zones at the brittle to viscous transition cap de creus ne spain a crustal scale shear zone network at the fossil brittle to viscous transition exposed at cap de creus ne spain evolved by coeval fracturing and viscous mylonitic overprinting of an existing foliation initial fracturing led to mylonitic shearing as rock softened in ductilely deformed zones surrounding the fractures mylonitic shear zones widened by lateral branching of fractures from these shear zones and by synthetic rotation of the existing foliation between the fractures and shear zones shear zones lengthened by a combination of fracturing and mylonitic shearing in front of the shear zone tips shear zones interconnected along and across their shearing planes separating rhomb shaped lozenges of less deformed rock lozenges were subsequently incorporated into the mylonitic shear zones by widening in the manner described above in this way deformation became homogeneous on the scale of initial fracturing metre to decametre scale in contrast the shear zone network represents localisation of strain on a decametre length scale the strength of the continental crust at the time of coeval fracturing and viscous shearing is inferred to have decreased with time and strain as fracturing evolved to mylonitic shearing and as the shear zones coalesced to form a through going network subparallel to the shearing plane crustal strength must therefore be considered as strain and scale dependent

mg ca variation in planktonic foraminifera tests implications for reconstructing palaeo seawater temperature and habitat migration the nature of compositional variability within the tiny calcitic shells tests that are precipitated by planktonic foraminifera has been investigated using laser ablation inductively coupled plasma mass spectrometry la icp ms systematic large and correlated variation of mg ca mn ca ba ca and zn ca but relatively uniform sr ca are observed through the test walls of analysed species globigerinoides sacculifer globigerinoides ruber neogloboquadrina pachyderma and neogloboquadrina dutertrei distinct chamber and chamber wall layer compositions can be resolved within individual tests and mg ca compositional differences observed in sequentially precipitated test components of the different species analysed are consistent with seawater temperature changes occurring with habitat migration during their adult life cycle stages estimated test calcification temperatures are in keeping with available seawater temperature constraints indicating the potential for accurate seawater temperature reconstruction using la icp ms mg rich 1 6 mol mg surface veneers that are also enriched in mn ba and zn have been found on all species and all fossil tests as well as on live sampled tests of g ruber with the latter suggesting a possible biogenic origin these mg rich surfaces bias bulk test compositions toward higher mg ca values by between 5 and 35

vertical distribution and isotopic fractionation of living planktonic foraminifera from the panama basin a model1 2 which explains the vertical and seasonal distribution of planktonic foraminifera was developed using data from the western north atlantic and is comprised of three tenets 1 the conditions in the photic zone upper 80 100 m exclusively dictate planktonic foraminifera species composition and abundance throughout the water column 2 species are vertically stratified within the photic zone according to their temperature preference depth distribution according to temperature preference has been proposed by several authors3 based on isotope analyses of sediments due to seasonal temperature variations seasonal variations in the 18o composition of seawater and species specific isotope fractionation rigorous proof of this hypothesis cannot be provided from sediment analyses alone 3 the chlorophyll maximum is a major food source zone which is preferentially exploited by foraminifera our data from the panama basin which are presented here are confirmation of this model the panama basin in the eastern equatorial pacific which has a shallow and steep thermocline was sampled for living planktonic foraminifera a multiple opening closing net and environmental sensing system mocness 4 was used to collect 13 sets of eight vertically stratified oblique samples we report here the quantitative distribution and stable isotopic composition of planktonic foraminifera from four mocness tows taken over 5 days during august 1979 rv knorr cruise 73 at 5 20 n 8 50 w each tow consisted of eight samples which integrated 12 5 m intervals from 0 to 100 m for moc 126 25 m intervals from 0 to 200 m for moc 127 100 150 m intervals from 0 to 1 000 m on moc 128 and 250 m intervals from 0 to 2 000 m on moc 131

modulation and daily banding of mg ca in orbulina universa tests by symbiont photosynthesis and respiration a complication for seawater thermometry the mg ca composition of calcium carbonate tests shells secreted by planktonic foraminifera is increasingly being employed to estimate past seawater temperatures and reconstruct paleocean and climate records spanning hundreds of thousands of years we show using two high resolution microanalysis techniques that the final chamber of the planktonic foraminifera orbulina universa typically comprises between three and six paired low and high mg growth bands the number and spacing of these bands is consistent with a diurnal origin modulated by changing ph within the foraminiferal microenvironment due to the day night photosynthesis respiration cycle of algal symbionts the amplitude of mg ca variation within individual tests and across many daily growth bands cannot be accounted for by seawater temperature in the shallow euphotic zone habitat of o universa our results indicate the mg ca composition of calcite precipitated by o universa in nature is strongly influenced by diurnal changes in the biological activity of algal symbionts and the host foraminifer this brings into question the fundamental premise often made in applying mg ca palaeoseawater thermometry that the mg ca composition of foraminiferal calcite is determined by seawater temperature and whether the mg ca composition of other planktonic species that are more widely used for palaeoseawater thermometry are subject to similar influences 2004 elsevier b v all rights reserved

core top calibration of mg ca in tropical foraminifera refining paleotemperature estimation 1 optimal use of mg ca as a paleotemperature proxy requires establishing calibrations for different species of foraminifera and quantifying the influence of dissolution to achieve this goal we have measured mg ca and 18o in a series of tropical and subtropical core tops including four depth transects the ceara rise the sierra leone rise and the rio grande plateau in the atlantic and the ontong java plateau in the pacific focusing on spinose mixed layer dwelling species globigerinoides ruber and globigerinoides sacculifer and nonspinose thermocline dwelling neogloboquadrina dutertrei shell mg ca in g sacculifer is 5 15 lower than in g ruber while n dutertrei mg ca is 49 55 lower than in g ruber this statistically significant offset has allowed us to establish different calibrations for each species multilinear regression analysis was used to develop calibration equations that include a correction term for the dissolution effect on mg ca in foraminiferal calcite presented in this paper are two sets of calibrations one set using core depth as a dissolution correction and another using co32 as a dissolution parameter the calibrations suggest that g ruber is the most accurate recorder of surface temperature while g sacculifer records temperatures below the surface at 20 30 m the depth habitat of n dutertrei is more uncertain owing to the wide range in habitat depths depending on hydrographic conditions but on average mg ca and 18o data suggest it is at 50 m of the three species n dutertrei is the most sensitive to dissolution up to 23 decrease in shell mg ca per km while g sacculifer is the most resistant

a 667 year record of coseismic and interseismic coulomb stress changes in central italy reveals the role of fault interaction in controlling irregular earthquake recurrence intervals current studies of fault interaction lack sufficiently long earthquake records and measurements of fault slip rates over multiple seismic cycles to fully investigate the effects of interseismic loading and co seismic stress changes on the surrounding fault network we model elastic interactions between 97 faults from 30 earthquakes since 1349 ad in central italy to investigate the relative importance of co seismic stress changes versus interseismic stress accumulation for earthquake occurrence and fault interaction this region has an exceptionally long 667 year record of historical earthquakes and detailed constraints on the locations and slip rates of its active normal faults of 21 earthquakes since 1654 20 events occurred on faults where combined co seismic and interseismic loading stresses were positive even though 20 of all faults are in stress shadows at any one time furthermore the coulomb stress on the faults that experience earthquakes is statistically different from a random sequence of earthquakes in the region we show how co seismic coulomb stress changes can alter earthquake inter event times by c 103 years and fault length controls the intensity of this effect static coulomb stress changes cause greater inter event perturbations on shorter faults in areas characterized by lower strain or slip rates the exceptional duration and number of earthquakes we model enable us to demonstrate the importance of combining long earthquake records with detailed knowledge of fault geometries slip rates and kinematics to understand the impact of stress changes in complex networks of active faults

slip distributions on active normal faults measured from lidar and field mapping of geomorphic offsets an example from l aquila italy and implications for modelling seismic moment release surface slip distributions for an active normal fault in central italy have been measured using terrestrial laser scanning tls in order to assess the impact of changes in fault orientation and kinematics when modelling subsurface slip distributions that control seismic moment release the southeastern segment of the surface trace of the campo felice active normal fault near the city of l aquila was mapped and surveyed using techniques from structural geology and using tls to define the vertical and horizontal offsets of geomorphic slopes since the last glacial maximum 15 3 ka the fault geometry and kinematics measured from 43 sites and throw heave measurements from geomorphic offsets seen on 250 scarp profiles were analysed using a modification of the kostrov equations to calculate the magnitudes and directions of horizontal principal strain rates the map trace of the studied fault is linear except where a prominent bend has formed to link across a former left stepping relay zone the dip of the fault and slip direction are constant across the bend throw rates since 15 3 ka decrease linearly from the fault centre to the tip except in the location of the prominent bend where higher throw rates are recorded vertical coseismic offsets for two palaeo earthquake ruptures seen as fresh strips of rock at the base of the bedrock scarp also increase within the prominent bend the principal strain rate calculated by combining strike dip slip direction and post 15 3 ka throw rate decreases linearly from the fault centre towards the tip the strain rate does not increase across the prominent fault bend the above shows that changes in fault strike whilst having no effect on the principal horizontal strain rate can produce local maxima in throw rates during single earthquakes that persist over the timescale of multiple earthquakes 15 3 ka detailed geomorphological and structural characterisation of active faults is therefore a critical requirement in order to properly define fault activity for the purpose of accurate seismic hazard assessment we discuss the implications of modelling subsurface slip distributions for earthquake ruptures through inversion of gps insar and strong motion data using planar fault approximations referring to recent examples on the nearby paganica fault that ruptured in the mw 6 3 2009 l aquila earthquake

isotopic signals in two morphotypes of globigerinoides ruber white from the south china sea implications for monsoon climate change during the last glacial cycle abstract based on the study of surface and downcore sediment samples from the south china sea scs two morphotypes of globigerinoides ruber white have been differentiated by taxonomic criteria at species and or subspecies level and also by their stable isotopic compositions of oxygen and carbon the two morphotypes g ruber sensu stricto s s and g ruber sensu lato s l represent two groups with different depth habitats with g ruber s s living in the upper 30 m of the water column and g ruber s l living at depths below 30 m the different depth habitats are indicated by the comparison between the present oceanographic data and isotopic signals of the two morphotypes in the surface sediment from the scs application of this information to a hemipelagic sediment core in the northern scs shows that drastic changes existed in the morphotypes isotopic records during the last glacial cycle the isotope difference between the two morphotypes diminished during 18 o stage 2 especially during the last glacial maximum it is inferred that this is the result of intensified monsoon winds which caused mixing of the upper layer of the water column during stage 2 the proportion of g ruber s l increased which is interpreted as a result of the increased productivity due to mixing of the subsurface nutrient rich water into the surface layer

factors which determine the hydrogeochemical behaviour of karstic springs a case study from the betic cordilleras spain the cabra alcaide karstic massif situated in the south of spain constitutes an important part of the so called natural park of the subbetic sierras this aquifer system is drained by various springs which supply a population of some 100 000 inhabitants the feed areas of these springs show very different characteristics with respect to their geological structure size of the drainage area thickness of the vadose zone elevation and degree of karstification in addition the carbonate rocks lie over a clayey substratum which contains large masses of intercalated evaporites due to these conditions the hydrochemical composition of the springs is relatively variable in this study a hydrogeochemical characterization of the aquifer in both space and time is undertaken and the factors that determine it are discussed to achieve this 19 monthly samples were taken from the 6 most significant springs of the hydrogeological system the commencement of sampling coincided with the transition from a period of several years of severe drought and a very wet two year period which amplified considerably the hydrochemical and hydrodynamic response of the springs to the recharge identification of hydrogeochemical processes was performed by studying hydrographs the temporal evolution of physico chemical parameters ionic ratios mainly mg ca and by means of simple and multivariate statistical analyses the saturation status was established using the wateqf program and the mass transfer was quantified using phreeqc with the exception of the epikarstic subsystem i e the zarza spring the majority of the results indicate that the aquifer exhibits a diffuse flow model in which piston flow phenomena are seen closely linked to the most intense precipitation along the direction of flow hydrochemical trends are seen as the water type changes from ca hco3 to ca mg hco3 at the same time enrichment in some ions derived from the dissolution of evaporitic minerals of the impermeable substratum and dedolomitization processes occur in this way almost 90 of the water samples were oversaturated in calcite the majority of cases being a consequence of the dissolution of the gypsum of the substratum only in the epikarstic springs can it be considered that the oversaturation in calcite is due to loss of co2 from the emerging groundwater it is concluded that hydrodynamic aspects together with hydrogeochemical characteristics need to be taken into account to correctly explain the hydrochemical evolution of the karstic springs moreover the use of both approaches permits a more accurate establishment of the degree of aquifer karstification which in turn needs to be known in order to assess its vulnerability to contamination and to protect recharge zones

modes of eastern equatorial pacific thermocline variability implications for enso dynamics over the last glacial period 1 changes in el nino southern oscillation enso variability are difficult to extract from paleoceanographic reconstructions because they are superimposed on changes in seasonal variability that modulate the first order climate signal here we address this problem by reconstructing thermocline structure from a marine sediment core retrieved from the eastern equatorial pacific at the core location changes in hydrologic parameters within the thermocline are linked to enso activity with a reduced influence of seasonal variability compared to surface waters we performed repeated isotopic analyses 18o on single specimens of the thermocline dwelling planktonic foraminifera neogloboquadrina dutertrei at several targeted time periods over the last 50 ka to extract the total thermocline variance a parameter supposed to reveal changes in enso no fundamental changes in amplitude and frequency of the events were detected despite differences in climatic background however our data suggest that long term variations in the thermocline variability occurred over the last 50 ka with the highest and lowest enso activities occurring during the last glacial period and the last glacial maximum respectively

a multiproxy assessment of the western equatorial pacific hydrography during the last 30 kyr foraminiferal species assemblages and uk37 0 1 2 c these estimates are consistent with estimates from other wpwp cores thereby suggesting that the discrepancy is due to proxy compatibility rather than differences in cores qualitity postdepositional dissolution above the lysocline might have altered the mg ca based temperature estimates in our site but this effect is insufficient to resolve discrepancies between mg ca in g ruber and the other proxies we suggest that the lower estimates obtained from mg ca in g sacculifer faunal transfer functions and uk37 0 might reflect subsurface temperature changes rather than strict surface estimates accounting for potential artefacts including dissolution and bioturbation we suggest that the glacial wpwp sst was about 2 5 0 7 c cooler than during the holocene whereas the subsurface upper thermocline temperature change was only about 1 8 0 7 c interpreting variations in d 18 osw in terms of salinity changes suggests a possibly slight decrease in surface salinity at the site of md97 2138 during the lgm though lgm freshening in md97 2138 is not robust to postdeposition dissolution effects this inferred freshening appears to be a general feature of the western equatorial pacific

uncertainties in seawater thermometry deriving from intratest and intertest mg ca variability in globigerinoides ruber intertest mg ca variability within these deep sea core top samples is a source of significant uncertainty in mg ca seawater temperature estimates and is notable for being site specific our results indicate that widely assumed uncertainties in mg ca thermometry may be underestimated we show that statistical power analysis can be used to evaluate the number of tests needed to achieve a target level of uncertainty on a sample by sample case a varying bias also arises from the presence and varying mix of two morphotypes g ruber ruber and g ruber pyramidalis which have different mean mg ca values estimated calcification temperature differences between these morphotypes range up to 5c and are notable for correlating with the seasonal range in seawater temperature at different sites

seasonal change in foraminiferal production in the western equatorial pacific warm pool evidence from sediment trap experiments seasonal changes in the flux of individual planktonic foraminifera in the deep ocean have been studied in the western equatorial pacific warm pool using material collected by sediment traps over a period of 1 yr 1991 1992 mean total foraminiferal fluxes tffs were 171 and 97 shells m 2 day 1 at sites n1 2 59 8 n 135 01 5 e and n2 4 07 5 n 136 16 6 e respectively the seasonal change in tffs was much higher than for organic matter om and carbonate fluxes the major species of planktonic foraminifera were pulleniatina obliquiloculata neogloboquadrina dutertrei globigerinoides sacculifer globigerinella aequilateralis and globigerinoides ruber symbiont bearing species and n dutertrei were predominant in the western equatorial pacific warm pool comparison between the warm pool and upwelling deep sea research ii 43 1996 1257 mar micropaleontology 33 1998 157 indicates that the foraminiferal assemblage trapped at the western equatorial pacific warm pool was comparable with the south equatorial and subtropical assemblages during a plankton tow study conducted at 140 w in 1992 it suggests that fairly oligotrophic conditions prevailed in the western equatorial pacific warm pool in association with terrestrial nutrient inputs or temporary mixing by wind bursts the om flux was more positively correlated with the 63 m carbonate fraction mainly composed of coccoliths r 0 87 and biogenic opal which suggests that om fluxes were more affected by phytoplankton productivity although food availability is generally important for foraminiferal production tffs were poorly correlated with om fluxes at sites n1 and n2 which is partly attributed to the significant influence of symbiont photosynthesis the 18o values of p obliquiloculata and n dutertrei showed maxima in association with high om fluxes during period 2 from august to october and period 4 from late december to april at site n1 reflecting thickening of the mixed layer following wind bursts g sacculifer showed a lunar reproduction cycle when between july and october carbonate production was more predominant than biogenic opal production a similar profile was evident for g ruber orbulina universa and g aequilateralis these four species are generally predominant at low latitudes therefore the lunar reproduction cycle may significantly affect the fluctuation in carbonate production in the equatorial ocean

progressive shoaling of the equatorial pacific thermocline over the last eight glacial periods the depth of equatorial pacific thermocline is diagnostic of the main modes of tropical climates past estimates of pacific thermocline dynamics have been reconstructed either for the last glacial maximum or on longer timescales at low resolution here we document a new high resolution set of reconstructed past sea surface and subsurface waters temperatures from the southwestern subequatorial pacific core md05 2930 in the gulf of papua over the last 800 ka we used two morphotypes of globigerinoides ruber known to live at different water depths to reconstruct past stratification we estimated calcification temperature of each morphotypes by mg ca paleothermometry our subequatorial pacific thermocline paleotemperature record indicates a response of the thermocline to both direct orbital forcing and glacial interglacial changes our stratification record shows a systematic shallower glacial thermocline whereas sea surface temperatures are characterized by precessional forcing the record is indicative of a progressive long term shoaling of the thermocline during the glacial stages during the late pleistocene the shoaling of the subequatorial pacific thermocline is consistent with regional estimates an enhanced south pacific shallow overturning wind driven circulation could have driven this progressive shoaling we speculate that this late pleistocene glacial shoaling of the thermocline could be related to an increase in the amplitude of the obliquity

timing and mechanism for intratest mg ca variability in a living planktic foraminifer abstract geochemical observations indicate that planktic foraminifer test mg ca is heterogeneous in many species thereby challenging its use as a paleotemperature proxy for paleoceanographic reconstructions we present mg ca and ba ca data collected by laser ablation icp ms from the shells of orbulina universa cultured in controlled laboratory experiments test calcite was labeled with ba spiked seawater for 12 h day or night calcification periods to quantify the timing of intratest mg banding across multiple diurnal cycles results demonstrate that high mg bands are precipitated during the night whereas low mg bands are precipitated during the day data obtained from specimens growing at 20 c and 25 c show that mg ca ratios in both high and low mg bands increase with temperature and average test mg ca ratios are in excellent agreement with previously published empirical calibrations based on bulk solution icp ms analyses in general mg band concentrations decrease with increasing ph and or co2 3 but this effect decreases as experimental temperatures increase from 20 c to 25 c we suggest that mitochondrial uptake of mg2 from the thin calcifying fluid beneath streaming rhizopodial filaments may provide the primary locus for mg2 removal during test calcification and that diurnal variations in either mitochondrial density or activity produce mg banding these results demonstrate that mg banding is an inherent component of test biomineralization in o universa and show that the mg ca paleothermometer remains a fundamental tool for reconstructing past ocean temperatures from fossil foraminifers

viscous roots of active seismogenic faults revealed by geologic slip rate variations viscous flow in the deep crust and uppermost mantle can contribute to the accumulation of strain along seismogenic faults in the shallower crust1 it is difficult to evaluate this contribution to fault loading because it is unclear whether the viscous deformation occurs in localized shear zones or is more broadly distributed2 furthermore the rate of strain accumulation by viscous flow has a power law dependence on the stress applied yet there are few direct estimates of what the power law exponent is over the long term for active faults here we measure topography and the offset along fault surfaces created during successive episodes of slip on seismically active extensional faults in the italian apennines during the holocene epoch we show that these data can be used to derive a relationship between the stress driving deformation and the fault strain rate averaged over about 15 thousand years kyr we find that this relationship follows a well defined power law with an exponent in the range of 3 0 3 3 1 this exponent is consistent with nonlinear viscous deformation in the deep crust and crucially strain localization promoted by seismogenic faulting at shallower depths although we cannot rule out some distributed deformation we suggest that fault strain and thus earthquake recurrence in the apennines is largely controlled by viscous flow in deep localized shear zones over many earthquake cycles

controls on shell mg ca and sr ca in cultured planktonic foraminiferan globigerinoides ruber white mg ca and sr ca ratios were determined on a single species of planktonic foraminiferan globigerinoides ruber white collected from the gulf of eilat and cultured in seawater at five different salinities 32 to 44 five temperatures 18 to 30 c and four ph values 7 9 to 8 4 the mg ca temperature calibration of cultured g ruber with an exponential slope of 8 3 c agrees well with previously published calibrations from core tops and sediment traps however the dependence of mg ca on salinity with an exponential slope of 5 3 psu is also significant and should be included in the calibration equation with this purpose we calculated a calibration equation for g ruber dependent on both temperature and salinity within the 95 confidence limits mg ca mmol mol exp 0 06 0 02 s psu 0 08 0 02 t c 2 8 1 0 r2 0 95 the influence of ph on mg ca ratios is negligible at ambient seawater ph 8 1 to 8 3 however we observe a dominating ph control on shell mg ca when the ph of seawater is lower than 8 0 sr ca in g ruber shows a significant positive correlation with average growth rate presumably part of the variability in shell sr ca in the geological record is linked to changes in growth rates of foraminifera as a response to changing environmental conditions

relationship between topography rates of extension and mantle dynamics in the actively extending italian apennines to investigate the mechanism driving active extension in the central and southern italian apennines and the geography of seismic hazard we compare spatial variations in upper crustal strain rate measured across exposed fault scarps since 15 3 ka with data on cumulative upper crustal strain and topographic elevation and free air gravity p wave tomography and sks splitting delay times that are a proxy for strain in the mantle high extensional strain rates across the apennines since 15 3 ka 0 4 3 1 mm yr along 90 km transects occur in two areas lazio abruzzo se campania and basilicata where values for finite extensional strains that have developed since 2 3 ma are highest 2 7 km cumulative throw and where mean elevation in 5 90 km ne sw boxes is 600 m the intervening area nw campania and molise with 600 m mean elevation in 5 90 km boxes has extension rates 0 4 mm yr and lower values for finite extensional strains 2 km cumulative throw these two areas with high upper crustal strain rates overlie mantle that has relatively long spatially interpolated sks delay times 1 2 1 8 s indicating relatively high mantle strains and free air gravity values 140 160 mgals the intervening area of lower extension rate has shorter spatially interpolated sks delay times 0 8 1 2 s and lower free air gravity values 120 mgals the two areas with high upper crustal strain rates and strain mean elevation and mantle strain coincide with the northern and southern edges of a slab window in the tyrrhenian apennines subducting plate that has been inferred from published p wave tomography together these correlations suggest that dynamic support of the topography by mantle flow through the slab window may control the present day upper crustal strain rate field in the apennines and the geography of seismic hazard in the region

plagioclase preferred orientation in layered mylonites evaluation of flow laws for the lower crust thesis s m joint program in marine geology and geophysics massachusetts institute of technology dept of earth atmospheric and planetary sciences and the woods hole oceanographic institution 2008

sea surface temperature and salinity reconstruction from coral geochemical tracers massive scleractinian corals secrete an aragonitic skeleton which incorporates a large array of chemical tracers corals present several advantages for palaeoclimate research they grow continuously and can live up to 1000 years they are easy to date and they can be sampled at high resolution weekly to monthly resolution both live and fossil corals can be collected in the field in the past two decades significant efforts have been made to identify robust tracers of sea surface temperature sst and salinity sss in corals to date sr ca and 18o are considered to be the most reliable sst tracers although changes in seawater 18o can significantly alter sst reconstructed from coralline 18o because these variations in seawater 18o can be linked to sss changes this initial problem can in fact be turned into an advantage and provide us with an sss tracer the sst component in the coral 18o signal can either be evaluated through sr ca measurements or in some case simply filtered out however there is still much uncertainty concerning the exact mode of incorporation of trace elements and stable isotopes into the coral skeleton the effects of growth rate light intensity feeding habits ph and water chemistry are still poorly documented a review of the strength and weaknesses of sr ca and 18o is presented together with some examples of sst and sss reconstructions other potential sst tracers are also reviewed it is expected that the ability to grow corals in aquarium under controlled conditions and that the development of sophisticated analytical techniques at the micrometric level should help us understand better the robustness of each tracers and the factors controlling their incorporation in coral aragonite

interactions between mantle upwelling drainage evolution and active normal faulting an example from the central apennines italy summary in this paper we show that the processes that have shaped the quaternary surface development of the apennines in central italy are all consequences of a single subcrustal process the upwelling of the mantle the relationship between gravity and topography shows that mantle convection is responsible for a long wavelength 150 200 km topographic bulge over the central apennines and stratigraphic evidence suggests this bulge developed in the quaternary active normal faulting is localized at the crest of this bulge and produces internally draining fault bounded basins these basins have been progressively captured by the aggressive headward erosion of major streams that cut down to the sea on the flanks of the regional bulge the only surviving closed basins are those on the apennine watershed most distant from the marine base level where continued normal faulting is still able to provide local subsidence that defeats their capture by the regional drainage network understanding the competition between regional capture and local fault related subsidence of intermontane basins is crucial for recognizing potentially hazardous active faults in the landscape and also for interpreting the sediment supply to adjacent offshore regions central italy provides a good modern analogue for processes that are probably common in the geological record particularly on rifted margins and intracontinental rifts but may not have been fully appreciated

determination of intratest variability of trace elements in foraminifera by laser ablation inductively coupled plasma mass spectrometry 1 we have developed a technique to determine the variability of trace elements including li b na mg mn cu zn sr and ba within foraminifera tests using laser ablation inductively coupled plasma mass spectrometry la icp ms this technique has a high spatial resolution width 40 80 m depth 0 5 m is reproducible 8 external reproducibility and has low detection limits generally 0 05 g g 1 we demonstrate that normalization of data to a calcite standard usually gives results that are more consistent with solution icp ms data than normalization to nist 612 rastering into the wall of the final chamber of globigerinoides sacculifer shows that the outermost 1 5 m of the test is enriched in trace elements including mn relative to the interior indicating the presence of a contaminant surface phase pustule calcite close to the aperture of globorotalia tumida has different sr ca and ba ca compared to other parts of the test sr ca and ba ca partition coefficients suggest that the pustule calcite is diagenetic and or formed in a more open system multiple analyses of orbulina universa tests recovered from a latitudinal transect in the north atlantic give a relationship between mg ca and sea surface temperature similar to that reported elsewhere in the literature these initial data demonstrate the validity of this technique and show that it is potentially an extremely powerful microanalytical tool for palaeoceanographic and palaeontological studies

climate impact of late quaternary equatorial pacific sea surface temperature variations magnesium calcium data from planktonic foraminifera in equatorial pacific sediment cores demonstrate that tropical pacific sea surface temperatures ssts were 2 8 0 7 c colder than the present at the last glacial maximum glacial interglacial temperature differences as great as 5 c are observed over the last 450 thousand years changes in sst coincide with changes in antarctic air temperature and precede changes in continental ice volume by about 3 thousand years suggesting that tropical cooling played a major role in driving ice age climate comparison of sst estimates from eastern and western sites indicates that the equatorial pacific zonal sst gradient was similar or somewhat larger during glacial episodes extraction of a salinity proxy from the magnesium calcium and oxygen isotope data indicates that transport of water vapor into the western pacific was enhanced during glacial episodes

the influence of salinity on mg ca in planktic foraminifers evidence from cultures core top sediments and complementary δ18o the mg ca ratio in foraminiferal calcite is one of the principal proxies used for paleoceanographic temperature reconstructions but recent core top sediment observations suggest that salinity may exert a significant secondary control on planktic foraminifers this study compiles new and published laboratory culture experiment data from the planktic foraminifers orbulina universa globigerinoides sacculifer and globigerinoides ruber in which salinity was varied but temperature ph and light were held constant combining new data with results from previous culture studies yields a mg ca sensitivity to salinity of 4 4 2 3 4 7 1 2 and 3 3 1 7 per salinity unit 95 confidence respectively for the three foraminifer species studied here comparison of these sensitivities with core top data suggests that the much larger sensitivity 27 4 per salinity unit derived from atlantic core top sediments in previous studies is not a direct effect of salinity rather we suggest that the dissolution correction often applied to mg ca data can lead to significant overestimation of temperatures we are able to reconcile culture calibrations with core top observations by combining evidence for seasonal occurrence and latitude specific habitat depth preferences with corresponding variations in physico chemical environmental parameters although both mg ca and 18o yield temperature estimates that fall within the bounds of hydrographic observations discrepancies between the two proxies highlight unresolved challenges with the use of paired mg ca and 18o analyses to reconstruct paleo salinity patterns across ocean basins the first step towards resolving these challenges requires a better spatially and seasonally resolved 18osw archive than is currently available nonetheless site specific reconstructions of salinity change through time may be valid

nonlinear strain buildup and the earthquake cycle on the san andreas fault two contrasting models of the earthquake deformation cycle on strike slip faults predict significant temporal declines in shear strain rate near the fault accompanied by a progressive broadening of the zone of deformation adjacent to it in the thin lithosphere model transient deformation results from flow in the asthenosphere due to stress relaxation following faulting through most or all of the lithosphere for an earth model with a thick elastic lithosphere plate thickness depth of seismic slip transient motions are due to postearthquake aseisrnic slip below the coseismic fault plane data from the san andreas fault indicate a long term temporal decrease in strain rate that persists for at least 30 years and may extend through the entire earthquake cycle observations support a cycle long rate decrease and a temporal spreading of the deformation profile only if movement cycles on the northern and southern locked sections of the fault are basically similar if so the usually lower strain rates and broader deformation zone currently observed on the southern san andreas represent a later evolutionary stage of the northern locked section where a great earthquake is a more recent occurrence although the data allow some extreme models to be discarded no sufficiently strong constraints exist to decide between the thin and thick lithosphere models regardless of the appropriate model the geodetic observations themselves indicate that strain buildup is sufficiently nonlinear to cause significant departures from recurrence estimates based on linear strain accumulation and the time predictable model

uncertainty in strain rate from field measurements of the geometry rates and kinematics of active normal faults implications for seismic hazard assessment abstract multiple measurements of the geometry kinematics and rates of slip across the auletta fault campania italy are presented and we use these to determine 1 the spatial resolution of field measurements needed to accurately calculate a representative strain rate 2 what aspects of the geometry and kinematics would introduce uncertainty with regard to the strain rate if not measured in the field we find that the magnitude of the post last glacial maximum throw across the fault varies along strike if such variations are unnoticed different values for a representative strain rate hence different results in seismic hazard calculations would be produced to demonstrate this we progressively degrade our dataset calculating the implied strain rate at each step excluding measurements can alter strain rate results beyond 1 uncertainty thus we urge caution when using only one measurement of slip rate for calculating hazard we investigate the effect of approximating the throw profile along the fault with boxcar and triangular distributions and show that this can underestimate or overestimate the strain rate with results in the range of 72 237 of our most detailed strain rate calculation we discuss how improved understanding of the potential implied errors in strain rate calculations from field structural data should be implemented in seismic hazard calculations

calibration of mg ca thermometry in planktonic foraminifera from a sediment trap time series 1 paired mg ca and 18o measurements on planktonic foraminiferal species g ruber white g ruber pink g sacculifer g conglobatus g aequilateralis o universa n dutertrei p obliquiloculata g inflata g truncatulinoides g hirsuta and g crassaformis from a 6 year sediment trap time series in the sargasso sea were used to define the sensitivity of foraminiferal mg ca to calcification temperature habitat depths and calcification temperatures were estimated from comparison of 18o of foraminifera with equilibrium calcite based on historical temperature and salinity data when considered together mg ca mmol mol of all species except two show a significant r 0 93 relationship with temperature t c of the form mg ca 0 38 0 02 exp 0 090 0 003 t equivalent to a 9 0 0 3 change in mg ca for a 1 c change in temperature small differences exist in calibrations between species and between different size fractions of the same species o universa and g aequilateralis have higher mg ca than other species and in general data can be best described with the same temperature sensitivity for all species and pre exponential constants in the sequence o universa g aequilateralis g bulloides g ruber g sacculifer other species this approach gives an accuracy of 1 2 c in the estimation of calcification temperature the 9 sensitivity to temperature is similar to published studies from culture and core top calibrations but differences exist from some literature values of pre exponential constants different cleaning methodologies and artefacts of core top dissolution are probably implicated and perhaps environmental factors yet understood planktonic foraminiferal mg ca temperature estimates can be used for reconstructing surface temperatures and mixed and thermocline temperatures using g ruber pink g ruber white g sacculifer n dutertrei p obliquiloculata etc the existence of a single mg thermometry equation is valuable for extinct species although use of species specific equations will where statistically significant provide more accurate evaluation of mg ca paleotemperature

evidence of power law flow in the mojave desert mantle studies of the earth s response to large earthquakes can be viewed as large rock deformation experiments in which sudden stress changes induce viscous flow in the lower crust and upper mantle that lead to observable postseismic surface deformation laboratory experiments suggest that viscous flow of deforming hot lithospheric rocks is characterized by a power law in which strain rate is proportional to stress raised to a power n refs 2 3 most geodynamic models of flow in the lower crust and upper mantle however resort to newtonian linear stress strain rate relations here we show that a power law model of viscous flow in the mantle with n 3 5 successfully explains the spatial and temporal evolution of transient surface deformation following the 1992 landers and 1999 hector mine earthquakes in southern california a power law rheology implies that viscosity varies spatially with stress causing localization of strain and varies temporally as stress evolves rendering newtonian models untenable our findings are consistent with laboratory derived flow law parameters for hot and wet olivine the most abundant mineral in the upper mantle and support the contention that at least beneath the mojave desert the upper mantle is weaker than the lower crust

variable fault geometry suggests detailed fault slip rate profiles and geometries are needed for fault based probabilistic seismic hazard assessment psha it has been suggested that a better knowledge of fault locations and slip rates improves seismic hazard assessments however the importance of detailed along fault slip rate profiles and variable fault geometry has not yet been explored we quantify the importance for modeled seismicity rates of using multiple throw rate measurements to construct along fault throw rate profiles rather than basing throw rate profiles on a single measurement across a fault we use data from 14 normal faults within the central italian apennines where we have multiple measurements along the faults for each fault we compared strain rates across the faults using our detailed throw rate profiles and degraded data and simplified profiles we show the implied variation in average recurrence intervals for a variety of magnitudes that result furthermore we demonstrate how fault geometry variable strike and dip can alter calculated ground shaking intensities at specific sites by changing the source to site distance for ground motion prediction equations gmpes our findings show that improved fault based seismic hazard calculations require detailed along fault throw rate profiles based on well constrained local 3d fault geometry for calculating recurrence rates and shaking intensities

temporal clustering of major earthquakes along individual faults due to post seismic reloading palaeoseismic evidence suggests that earthquake recurrence intervals in some regions can be highly variable with clusters of multiple large events separated by much longer periods of quiescence because post seismic processes have a significant effect on the reloading rate of the coseismic fault we hypothesize that temporal variations in the amount of stress concentrated in the non seismogenic lithosphere can modulate large earthquake recurrence times we explore this hypothesis using simple analogue spring dashpot slider models we find that in the presence of small amounts of environmental noise post seismic stress transfer over timescales much longer than an earthquake cycle may be an important factor in generating clustering behaviour the propensity for the system to be clustered is a function of a non dimensional number that we call the wallace number w w is defined as the average earthquake stress drop divided by the product of the long term geologic strain rate across the fault and the effective viscosity of the system our results indicate that environments with relatively low strain rates and a relatively weak non seismogenic lithosphere are most susceptible to clustering driven by post seismic stress recycling mechanisms

comparison of earthquake strains over 102 and 104 year timescales insights into variability in the seismic cycle in the central apennines italy in order to study the existence of possible deficits or surpluses of geodetic and earthquake strain in the lazio abruzzo region of the central apennines compared to 15 3 kyrs multi seismic cycle strain rates horizontal strain rates are calculated in 5 km x 5 km and 20 km x 20 km grid squares using slip vectors from striated faults and offsets of late pleistocene holocene landforms and sediments strain rates calculated over 15 3 kyrs within 5 km x 5 km grid squares vary from zero up to 2 34 0 54 x 10 7 yr 1 and resolve variations in strain orientations and magnitudes along the strike of individual faults surface strain rates over a time period of 15 3 kyrs from 5 km x 5 km grid squares integrated over an area of 80 km x 160 km shows the horizontal strain rate of the central apennines is 1 18 0 04 0 12 x10 8 yr 1 and 1 83 4 43 3 80 x 10 10 yr 1 parallel and perpendicular to the regional principal strain direction 043 degrees 223 degrees 1 degrees associated with extension rates of ms 6 0 magnitude historical earthquakes have been reported to be as low as zero this demonstrates the importance of comparing the exact same areas and that strain rates vary spatially on the length scale of individual faults and on a timescale between 10 2 yr and 10 4 yr in the central apennines we use these results to produce a fault specific earthquake recurrence interval map and discuss the regional deformation related to plate boundary and sub crustal forces temporal earthquake clustering and the natural variability of the seismic cycle

saline groundwater in israel its bearing on the water crisis in the country abstract one of the major causes for the deterioration of water quality bearing heavily on the water crisis in israel is the ongoing contamination of its water resources by saline water bodies the present paper reviews the geochemical processes forming saline water lists and explains certain chemical and isotopic parameters which enable understanding these processes and describes the saline groundwater bodies and various salinization phenomena occurring in the country s various aquifers deterioration of groundwater in israel is caused by numerous natural processes such as encroachment of sea water migration of connate highly pressurized brines penetrating into fresh groundwater by subsurface dissolution of soluble salts originating in surrounding country rocks and by water rock interaction in addition to sea water two saline water bodies were identified as the main factors causing salinization of fresh groundwater a ca chloride brines encountered in the jordan dead sea rift valley in various parts of the negev and of the coastal plain and b na chloride saline water identified in the subsurface of the negev and in the southern part of the coastal plain intensive exploitation of groundwater in israel has disturbed the natural equilibrium which prevailed between fresh and saline water the newly established groundwater flow regimes have facilitated the migration of saline water bodies their participation in the active hydrological cycle and the progressive contamination of fresh groundwater these processes which were not anticipated by planners and water resources managers emphasize that large scale groundwater exploitation was undertaken without giving sufficient consideration to the occurrence and subsurface migration of saline water and brines

single foraminifera mg ca analyses of past glacial interglacial temperatures derived from g ruber sensu stricto and sensu lato morphotypes abstract the ratio of magnesium to calcium mg ca in foraminiferal shells is commonly used as a proxy for past ocean temperature recent advances in elemental analyses now enable single specimen measurements of planktic foraminifera and thus can provide information on past seasonal and interannual variability owing to the near monthly lifespan of foraminifera in this study we explore the temperature variance recorded by mg ca in tests of foraminifera globigerinoides ruber a planktic species that occurs throughout the year in tropical waters using la icp ms we characterize mg ca variability in single specimens of two morphotypes of g ruber picked from a sediment core retrieved offshore new caledonia we provide an estimate of the range of calcification temperatures for these morphotypes during five interglacial glacial cycles over the last 1 55 ma first we find significant and systematic differences between the morphotypes and second the temperature difference between morphotypes does not remain constant through time our results highlight a progressive increase in surface water temperatures during interglacials and a progressive decrease in glacial subsurface water temperatures these changes in surface and subsurface temperatures potentially highlight a change in the stratification of the water column over the mid pleistocene transition we conclude that single specimen mg ca on foraminiferal morphotypes can offer unique perspectives on paleoenvironmental reconstructions

interlaboratory comparison study of mg ca and sr ca measurements in planktonic foraminifera for paleoceanographic research thirteen laboratories from the usa and europe participated in an intercomparison study of mg ca and sr ca measurements in foraminifera the study included five planktonic species from surface sediments from different geographical regions and water depths each of the laboratories followed their own cleaning and analytical procedures and had no specific information about the samples analysis of solutions of known mg ca and sr ca ratios showed that the intralaboratory instrumental precision is better than 0 5 for both mg ca and sr ca measurements regardless whether icp oes or icp ms is used the interlaboratory precision on the analysis of standard solutions was about 1 5 and 0 9 for mg ca and sr ca measurements respectively these are equivalent to mg ca based temperature repeatability and reproducibility on the analysis of solutions of 0 2 c and 0 5 c respectively the analysis of foraminifera suggests an interlaboratory variance of about 8 rsd for mg ca measurements which translates to reproducibility of about 2 3 c the relatively large range in the reproducibility of foraminiferal analysis is primarily due to relatively poor intralaboratory repeatability about 1 2 c and a bias about 1 c due to the application of different cleaning methods by different laboratories improving the consistency of cleaning methods among laboratories will therefore likely lead to better reproducibility even more importantly the results of this study highlight the need for standards calibration among laboratories as a first step toward improving interlaboratory compatibility

eastward glacier like flow of the tibetan crust constrained from power law rheology abstract we propose that topography can be used as a proxy for the eastward lateral glacier like flow of the tibetan crust in the himalayan tibetan orogenic system geodetic observations across the tibetan plateau indicate 22 mm yr of crustal motion with respect to stable eurasia by considering newtonian channel flow model further correlation between regional strain rate e and topographic elevation h is found to be statistically robust with stress exponent n of 3 03 0 1 therefore we suggest that the tibetan crust follows well defined power law relation that is consistent with the nonlinear deformation associated with dislocation creep moreover the predicted viscosity range of the tibetan crust is consistent with the channel flow model proposed by previous investigators using different approaches in different time scales

mesoscale structure of the mean east australian current system and its relationship with topography abstract we document the mean circulation of the east australian current eac system which is the major western boundary current in the southwest pacific ocean a new high resolution climatology of the region csiro atlas of regional seas cars is used to produce regional fields of steric height and sections of geostrophic velocity the realism of these fields has been enhanced by the high spatial resolution allowance for bathymetric control and the influence of land barriers the increased detail in the maps and sections reveal the major influence that the complex regional topography has on the circulation the results also provide the appropriate resolution for comparison with recent model studies of the region we have been able to both resolve well known features with greater detail and identify previously unrecognized aspects of the circulation important results include 1 the zonal inflow north of 30 s breaks into a series of individual jets after flowing through the island chains as suggested by recent model results 2 the interaction of the zonal inflow with the local topography as it undergoes bifurcation is documented 3 a detailed picture of the evolution of the eac at the western boundary is presented including surface currents and transports 4 separation and recirculation of the eac within the tasman abyssal basin are shown to occur as a double cell structure constrained by bathymetry 5 the eac outflow is resolved as a series of eastward and northeastward currents 6 the path of the tasman front is defined as it interacts with the tasman ridge systems 7 a quasi permanent eddy is identified for the first time adjacent to the norfolk ridge northwest of new zealand

coulomb stress transfer and fault interaction over millennia on non planar active normal faults the mw 6 5 5 0 seismic sequence of 2016 2017 central italy in order to investigate the importance of including strike variable geometry and the knowledge of historical and palaeoseismic earthquakes when modelling static coulomb stress transfer and rupture propagation we have examined the august october 2016 a d and january 2017 a d central apennines seismic sequence mw 6 0 5 9 6 5 in 2016 a d ingv and mw 5 1 5 5 5 4 5 0 in 2017 a d ingv we model both the coseismic loading from historical and palaeoseismic earthquakes and interseismic loading derived from holocene fault slip rates using strike variable fault geometries constrained by fieldwork the inclusion of the elapsed times from available historical and palaeoseismological earthquakes and on faults enables us to calculate the stress on the faults prior to the beginning of the seismic sequence we take account the 1316 4155 yr elapsed time on the mt vettore fault that ruptured during the 2016 a d seismic sequence implied by palaeoseismology and the 377 and 313 yr elapsed times on the neighbouring laga and norcia faults respectively indicated by the historical record the stress changes through time are summed to show the state of stress on the mt vettore laga and surrounding faults prior to and during the 2016 2017 a d sequence we show that the build up of stress prior to 2016 a d on strike variable fault geometries generated stress heterogeneities that correlate with the limits of the main shock ruptures hence we suggest that stress barriers appear to have control on the propagation and therefore the magnitudes of the main shock ruptures

improved extended reconstruction of sst 1854 1997 abstract an improved sst reconstruction for the 1854 1997 period is developed compared to the version 1 analysis in the western tropical pacific the tropical atlantic and indian oceans more variance is resolved in the new analysis this improved analysis also uses sea ice concentrations to improve the high latitude sst analysis and a modified historical bias correction for the 1939 41 period in addition the new analysis includes an improved error estimate analysis uncertainty is largest in the nineteenth century and during the two world wars due to sparse sampling the near global average sst in the new analysis is consistent with the version 1 reconstruction the 95 confidence uncertainty for the near global average is 0 4 c or more in the nineteenth century near 0 2 c for the first half of the twentieth century and 0 1 c or less after 1950

palaeoenvironmental analysis of early pleistocene brackish marshes in the rieti and tiberino intrapenninic basins latium and umbria italy using ostracods crustacea abstract recent palaeontological and sedimentological studies on the upper pliocene lower pleistocene continental deposits of the rieti and tiberino basins latium and umbria italy showed the existence of brackish marshes influenced by the early pleistocene tyrrhenian sea the micropaleontological analyses carried out on five sections cropping out in the northern sector of the rieti basin and on one section cropping out in the southwestern branch of the tiberino basin showed the repeated alternance of two ostracod assemblages the first is characterized by a very abundant ostracod association dominated by cyprideis torosa typical of brackish waters the second one is less rich in specimens and dominated by several species of freshwater candoninae this alternance allowed the recognition of several changes in the water salinity that could be related to many early pleistocene sea level changes palaeosalinities were estimated for both the tiberino and the rieti basin using the morphological analysis of the shell of cyprideis torosa ornamentation nodosities and percentages of sieve type pore canals the obtained palaeosalinity values ranging from freshwater to oligohaline show slightly higher salinities for the tiberino basin located nearer the ancient coastline than for the rieti basin

the relationship between surface kinematics and deformation of the whole lithosphere the variation of mechanical properties with depth in the lithosphere determines the relationship between surface deformation and whole lithosphere deformation hence between surface deformation and whole lithosphere dynamics where viscosity or elastic strength is a continuous function with depth surface deformation can be used to constrain both force balance and rheological parameters where viscosity is discontinuous but the upper crust and mantle lithosphere have comparable maximum values surface deformation can be used to approximate force balance and rheological parameters but tradeoffs mean that estimates of stress and viscosity are effective equivalent values rather than actual values where viscosity is both discontinuous and differs by much more than an order of magnitude between the upper crust and mantle lithosphere information about both force balance and rheology are absent from the surface deformation so surface observations alone are insufficient to estimate either the dynamic or mechanical state of the lithosphere

occurrence of partial and total coseismic ruptures of segmented normal fault systems insights from the central apennines italy abstract normal faulting earthquakes rarely rupture the entire extent of active normal faults and can also jump between neighbouring faults this confounds attempts to use segmentation models to define the likelihood of future rupture scenarios we attempt to study this problem comparing the offsets produced in single earthquakes with those produced by multiple earthquakes over longer timescales together with detailed studies of the structural geology we study the active normal fault system that caused the mw 6 3 2009 l aquila earthquake in central italy comparing the spatial distribution of coseismic offsets cumulative offsets that have developed since 15 3 ka and the total offsets that have accumulated since the faults initiated at 2 3 ma our findings suggest that 1 faults within a segmented fault system behave as a single interacting fault segment over time periods including multiple earthquake cycles e g 2 3 ma or 15 3ka with single earthquakes causing either partial or total ruptures of the entire system 2 an along strike bend causes throw and throw rates enhancements within the bend throughout the seismic history of the fault system we discuss the synchronised and geometrically controlled activity rates on these faults in terms of the propensity for floating earthquakes multi fault earthquakes and seismic hazard

statistical constraints on el nino southern oscillation reconstructions using individual foraminifera a sensitivity analysis recent investigations of submillennial paleoceanographic variability have attempted to resolve high frequency climate signals such as the el nino southern oscillation enso using the population statistics of individual planktic foraminiferal 18o analyses this approach is complicated by the relatively short lifespan of individual foraminifers 2 4 weeks compared to the time represented by a typical marine sediment sample decades to millennia here we investigate the uncertainty associated with individual foraminiferal analyses ifa through simulations on forward modeled 18ocarbonate first focusing on the nino3 4 region of the tropical pacific ocean a bootstrap monte carlo algorithm is developed to constrain the uncertainty on ifa statistics subsequently to test the sensitivity of ifa to changes in seasonal cycle amplitude enso amplitude and enso frequency synthetic time series of 18ocarbonate with differing variability are constructed and tested with our algorithm the probabilities of the ifa technique in detecting changes in enso amplitude and seasonal cycle amplitude or a combination of both for the surface ocean and thermocline at different locations in the tropical pacific are quantified we find that the uncertainty in the standard deviation is smaller than the range that the ifa signal is insensitive to enso frequency and at certain locations the seasonal cycle may dominate enso ifa sensitivity towards enso is highest at the central equatorial pacific surface ocean and the eastern equatorial pacific eep thermocline whereas sensitivity towards the seasonal cycle is highest at the eep surface ocean our results suggest that rigorous uncertainty quantification should become standard practice for accurately interpreting ifa data

glacial interglacial changes in the east australian current the east australian current eac is the western boundary current of the south pacific gyre transporting warm tropical waters to higher southern latitudes recent modelling shows that the partial separation of the eac 32 s and the coupled formation of the tasman front 34 s are caused by a steep gradient in the zonally integrated wind stress curl analysis of oxygen isotope ratios 18o in the planktonic foraminifer globigerinoides ruber from sediment cores from the coral sea and tasman sea indicates that the eac separation shifted northward to between 23 and 26 s during the last glacial we suggest these results indicate a significant change in the pacific wind stress curl during the glacial given recent evidence for el nino like conditions in the pacific during the last glacial with a reduction in the east west sea surface temperature sst gradient we suggest that weaker trade winds combined with more northerly stronger westerlies were associated with a change to the wind stress curl which repositioned the eac separation and tasman front in contrast by 11 ka bp the eac separation was forced south of 26 s this southward shift was synchronous with a rapid warming of tropical ssts and the onset of a la nina like sst configuration across the tropical pacific it appears that the south pacific trade winds strengthened accordingly causing the eac to readjust its flow this readjustment of the eac marks the onset of modern surface ocean circulation in the southwest pacific but the present eac transport was only achieved in the late holocene after 5 ka bp

approaches to unravel seasonality in sea surface temperatures using paired single specimen foraminiferal δ18o and mg ca analyses 1 seasonal changes in surface ocean temperature are increasingly recognized as an important parameter of the climate system here we assess the potential of analyzing single specimen planktonic foraminifera as proxy for the seasonal temperature contrast seasonality oxygen isotopes and mg ca ratios were measured on single specimens of globigerinoides ruber extracted from surface sediment samples of the mediterranean sea and the adjacent atlantic ocean variability in 18o and mg ca was then compared to established modern seasonal changes in temperature and salinity for both regions the results show that 1 average 18o derived temperatures correlate with modern annual average temperatures for most sites 2 the range in 18o and mg ca derived temperature estimates from single specimen analysis resembles the range in seasonal temperature values at the sea surface 0 50 m in the mediterranean sea and the atlantic ocean and 3 there is no strong correlation between mg ca and 18o derived temperatures from the same specimens in the current data set indicating that other parameters salinity carbonate ion concentration symbiont activity ontogenesis and natural variability potentially affect these proxies

spatial and temporal variations in growth rates along active normal fault systems an example from the lazio abruzzo apennines central italy abstract the geometry kinematics and rates of active extension in lazio abruzzo italian apennines have been measured in order to gain a better understanding of the spatial and temporal variations in fault growth rates and seismic hazards associated with active normal fault systems we present fault map traces throws throw rates and slip directions for 17 parallel en echelon or end on active normal faults whose 20 40 km lengths combine to form a soft linked fault array ca 155 km in length and ca 55 km across strike throw rates derived from observations of faulted late glacial features and holocene soils show that both maximum throw rates and throw rate gradients are greater on centrally located faults along the strike of the array total throws and throw gradients show similar spatial variations but with weaker relationships with distance along strike when summed across strike throw rates are increasingly high towards the centre of the array relative to summed throws we interpret the above to suggest that throw rates have changed in the recent past ca 0 7 ma from spatially random fault growth rates initiating at 2 5 3 3 ma to growth rates that are greater on centrally located faults we interpret this as evidence for fault interaction producing throw rate variations that drive throw profile readjustment on these crustal scale soft linked faults the results are used to discuss seismic hazards in the region which are quantified in a second paper in this issue

characterization of mg ca distributions in planktonic foraminifera species by electron microprobe mapping 1 the distribution of mg ca within the tests of eight modern planktonic foraminifer species has been characterized using electron microprobe mapping species include several that are commonly used for estimation of past seawater temperatures globigerinoides ruber g sacculifer neogloboquadrina incompta synonym of n pachyderma dex n dutertrei and g truncatulinoides each of the investigated species displays large variations in mg ca composition within individual tests however the pattern of mg ca variation is notably different between symbiont bearing and symbiont free species in symbiotic species cyclic mg ca compositional banding occurs that is characterized by narrow 1 3 m high mg ca typically 8 11 mmol mol bands intercalated between broader low mg ca typically 1 5 mmol mol bands this factor of 2 3 difference equates to an apparent calcification temperature change of 10 c or more such temperature changes are considered highly improbable and suggest vital effects significantly modify the incorporation of mg ca into the tests of symbiont bearing species these vital effects remain poorly understood and demand further careful evaluation as they may need to be accounted for when making reliable reconstructions of past oceanic temperatures symbiont free species typically have fewer and broader compositional bands that may reflect more closely changes in calcification temperature as these species migrate within a water column