tectonosphere of the earth upper mantle and crust interaction abstract the endogenic geological processes which include tectonic magmatic and metamorphic processes form regular combinations called endogenic regimes these regimes are geosynclinal orogenic platform rift tectonic magmatic activation diwa taphrogenic plateau basalt oceanic basins and mid oceanic ridges the endogenic regimes are connected with the peculiarities of the structure composition and state of the entire tectonosphere i e not only of the crust but of the upper mantle as well heat flow is a major factor controlling the type of the regime the other conditions are the temperature distribution in the tectonosphere and the degree and type of penetrability of the tectonosphere to melts and fluids there is a certain regular succession of regimes the structural evolution of the tectonosphere and the transformation of the matter in it are in close relationship the main trend in the development of the tectonospheric material is directed towards geochemical depletion of the upper mantle by fractioning at the initial stages fractioning occurred mostly by degassing and under these conditions the continental crust was formed rich in non compatible elements at that stage the calc alkaline magmas prevailed as the upper mantle was depleted and began to lose its volatiles the mechanism of fractioning changed degassing was substituted for selective melting and in this environment most of the tholeiitic magmas were formed this change in magma composition and in fractioning mechanism was combined with the destruction of the continental crust and the formation of the oceanic crust the diwa regime and the rifts were the first steps in the destruction of continental crust the stages that followed were represented by taphrogenic regimes at various levels these kinds of regimes were manifested in deep continental and marine depressions compensated and not compensated by sediments taphrogenic regimes are advancing from the east and west onto the eurasian continent in the east they form marginal seas and cause subsidence of the eastern parts of the chinese platform in the west they produce collapses of the crust in the mediterranean area the major crisis occurred between the palaeozoic and mesozoic and since that time the process of substitution of the continental crust by the oceanic crust has proceeded over increasingly large territories the evolution of the tectonosphere instigated by the changes in its matter was further complicated by temporal and spatial irregularities in deep heat escape which caused the alternation of excited and quiescent endogenic regimes tectonomagmatic periodicity and their co existence the combination of all these phenomena creates the structural inhomogeneity of the earth s crust at any stage of its history

hard and soft bottom thanatofacies from the santa maria di leuca deep water coral province mediterranean thanatofacies and the skeletonized components of the living facies from which they originate have been studied from the santa maria di leuca sml deep water coral mound province faunal analysis was carried out by means of bottom sampling and underwater video observations taking into account all benthic taxonomic groups mostly corals molluscs serpulids bryozoans ostracods foraminifers and barnacles which permitted recognition of six different facies these thanatofacies are easily distinguishable and appear to be largely corresponding and overlapping with related living facies some occur in mound areas others in the intermound ones they are as follows the framework building coral facies fc characterised by colonial corals mostly madrepora oculata the coral rubble facies cr with proximal and distal aspects characterised by large to small sized and densely to loosely packed coral fragments the solitary coral facies sc dominated by different species depending on the availability and dimensions of hard exploitable surfaces the gryphus and isidella facies gi in relatively coarse grained bottoms the mollusc mud facies mm and the foraminifer mud facies fm in comparably homogeneous silty bottoms facies distribution and spatial variability are discussed in relation to hydrology and sea floor topography furthermore the sml facies are compared with living facies from the present day mediterranean and pleistocene sediments of the same area data on bioclastic assemblages can serve for comparison with other recent aphotic non tropical carbonates

formerly emerging crustal blocks in the equatorial atlantic abstract anomalous crustal topographic highs exceeding the level predicted by the thermal contraction model by up to 2 3 km are observed along the romanche transform zone in the equatorial atlantic previous studies of shallow water reef limestones recovered from one of the shallowest sites on these crustal highs indicated that this site was at or above sea level 5 million years ago and subsided since at an average rate one order of magnitude faster than the subsidence estimated by thermal contraction of the crust seismic reflection profiles obtained across the romanche transform zone suggest that the anomalous highs are capped by reef limestones not only where limestones were actually sampled but also at other locations these findings support the idea that long segments of crust reached close to sea level in the past along the romanche transform zone the vertical crustal motions are probably caused by tectonism typical of long offset transforms inasmuch as the romanche has been a ridge ridge transform since the earliest stages of the opening of the equatorial atlantic it is likely that intense vertical tectonic motions occurred along it throughout the evolution of the atlantic support for this hypothesis is provided by the recovery during dsdp leg 4 of shallow water reef limestone of the eocene age from the summit of the north brazilian ridge along the western extension of the romanche fracture zone the presence of shallow or emergent crust across the equatorial zone during the early stages of opening had probably important consequences upon the water circulation between the north and the south atlantic and may even have provided land bridges for faunal migrations between africa and south america in early cenozoic times after the two continents had already separated

electrical resistivity tomography of vadose water movement cross borehole electrical resistivity tomography ert was used to image the resistivity distribution before and during two infiltration experiments in both cases water was introduced into the vadose zone and the change in resistivity associated with the plume of wetted soil was imaged as a function of time the primary purpose of this work was to study the capabilities and limitations of ert to image underground structure and ground water movement in the vadose zone a secondary goal was to learn specifics of unsaturated flow in a complex geologic setting tomographs of electrical resistivity taken before infiltration image coarser well drained soils sands and gravels as more resistive zones whereas finer grained soils silts and clays which hold more water by capillarity are imaged as more conductive images of changes in resistivity during infiltration show growth of the water infiltration plume with time that is consistent with known geology in the ert images we see the effects of capillary barriers and infer differences between capillary driven flow through fine sediments and gravity driven flow through very permeable sediments images are consistent with numerical flow simulations using hydrological parameter values consistent with soil types inferred from well logs ert can be a useful tool to monitor movement of circuitous moisture fronts in a heterogeneous field setting that would go undetected by borehole measurements

growth rates of the deep sea scleractinia desmophyllum cristagalli and enallopsammia rostrata with uranium rich skeletons and density bands similar to their surface coral counterparts deep sea scleractinia are a promising archive of past climate to improve the utility of fossil samples as monitors of deep ocean variability we have measured 210 pb and 226 ra activities in a variety of modern specimens to constrain the range of growth rates mechanical and chemical cleaning of each sample are required to isolate the radionuclides trapped in the coral skeleton from surface contaminants however in many cases mechanically cleaned samples show the same overall growth rate as parallel transects of samples subjected to the full chemical and mechanical cleaning but with much higher overall activities three samples of desmophyllum cristagalli show a range of vertical extension rates from 0 5 mm yr to 2 mm yr consistent with previous estimates a single enallopsammia rostrata from the north atlantic is over 100 years old its average radial growth rate is 0 07 mm yr and the clear banding in this direction is not consistent with annual periodicity a minimum vertical extension rate of 5 mm yr is estimated from the 210 pb data both of these species are found in the fossil record and with the growth rates determined here can record about 100 years of climate change the growth rates will allow the reconstruction of climate at subdecadal resolution in d cristagalli and even higher resolution in e rostrata d 2004 elsevier b v all rights reserved

influence of late cenozoic mountain building on ocean geochemical cycles in a steady state ocean input fluxes of dissolved salts to the sea must be balanced in mass and isotopic value by output fluxes for the elements strontium calcium and carbon rivers provide the primary input whereas marine biogenic sedimentation dominates removal dissolved fluxes in rivers are related to rates of continental weathering which in turn are strongly dependent on rates of uplift the largest dissolved fluxes today arise in the himalayan and andean mountain ranges and the tibetan plateau during the past 5 m y uplift rates in these areas have increased significantly this suggests that weathering rates and river fluxes may have increased also the oceanic records of carbonate sedimentation level of the calcite compensation depth and delta sup 13 c and delta sup 87 sr in biogenic sediments are consistent with a global increase in river fluxes since the late miocene the cooling of global climate over the past few million years may be linked to a decrease in atmospheric co sub 2 driven by enhanced continental weathering in these tectonically active regions

geochemistry and timing of the marginal basin and arc magmatism in the philippine sea available data enable the recognition of three periods of back arc crustal generation and three pulses of volcanic activity along the associated island arcs of the philippine sea the geochemistry of the basalts from the back arc basins of different ages indicates that in most cases they are identical to mid ocean ridge basalts and therefore should have similar sources and origins in contrast the island arc rock composition is variable in space and time reflecting the different source and more complex nature of corresponding magmatism geomagnetic studies and recent deep sea drilling project results suggest an alternate sequence of back arc and arc magmatic cycles both geochemical and geological observations provide important constraints on models of magmatism and extensions tectonics at convergent plate boundaries

the effect of lithospheric phase transitions on subsidence of extending continental lithosphere abstract a new simple model for sedimentary basin formation which combines both stretching and phase transitions occurring together in the lithosphere is proposed and two important aspects in sedimentary basin formation are addressed 1 the explanation of the domal uplift preceding rifting and 2 the ability of the model to explain the contradiction between a small amount of crustal stretching and the large amount of thermal subsidence without the need to invoke differential stretching between the crust and mantle relationships for synrift initial and thermal post rift subsidence are derived the model predicts that extension of continental lithosphere could produce synrifting uplift up to a threshold amount of extension and then subsidence for greater extension three dimensionless parameters quantify the contribution of the phase transition to the subsidence history 1 the clapeyron slope normalized to the initial geothermal gradient 2 the ratio of depth of phase transition to the thickness of the lithosphere and 3 the ratio of density effect due to phase transition to the change in density due to thermal expansion an evaluation of these parameters has been carried out by using thermodynamical data for the garnet spinel transition for upper mantle rocks our simple model shows that by including the effects of lithospheric phase transition in existing stretching models of sedimentary basin formation we can obtain an extra significant parameter controlling the subsidence and the entire extensional tectonics of such basins

from high plateaux to marginal basins the active role of the mantle current geodynamic models pose many serious problems for the description of continental tectonic processes serious difficulties arise also in the description of some of the ocean basins deformation of the earth s crust appears to be concentrated along several mobile megashear belts it is proposed that these could be the surficial expression of mantle chimneys which extend to great depths within these structures post orogenic high plateaux form and as time passes these develop a central depression enclosed within arcs or indeed full scale rings of mountains the enlargement and deepening over time of the back arc depression occurs in concert with the radial migration of a topographic wave in this respect the following structures represent different phases in an evolutionary sequence a the tibetan plateau b the north american cordillera and c the tyrrhenian basin and calabrian arc the development of this succession reflects a particularly high degree of activity in the mantle in which diapiric rising of asthenospheric matter elevates the land and causes tensional rifting the resulting centrifugal movement of the mantle melt results in crustal foundering and engulfment of the area behind the arc which thus becomes susceptible to the subsequent processes of com pressional deformation

observing lingering hyporheic storage using electrical resistivity variations around stream restoration structures crabby creek pa time lapse geophysical surveys can map lingering hyporheic storage by detecting changes in response to saline tracer tracer tests were conducted in crabby creek an urban stream outside philadelphia to examine the influence of stream restoration structures and variable sediment thickness we compared electrical resistivity surveys with extensive well sampling 57 wells in two 13 5 m long reaches each with a step drop created by a j hook the two step drops varied in tracer behaviour based on both the well data and the geophysical data the well data showed more variation in arrival time where the streambed sediment was thick and was more uniform where sediment was thin the resistivity in the reach with thin sediment showed lingering tracer in the hyporheic zone both upstream and downstream from the j hook in the second reach where the sediment was thicker the lingering tracer in the hyporheic zone was more extensive downstream from the j hook the contrasting results between the two reaches from both methods suggested that sediments influenced hyporheic exchange more than the step at this location resistivity inversion differed from well data in both reaches in that it showed evidence for tracer after well samples had returned to background mapping lingering tracer either upstream or downstream of a step we conclude that resistivity surveys may become an important tool for hyporheic zone characterization because they provide information on the extent of slow moving fluids in the hyporheic zone which have the potential to enhance chemical reactions copyright 2012 john wiley sons ltd

the sardinian cold water coral province in the context of the mediterranean coral ecosystems abstract a new cold water coral cwc province has been identified in the mediterranean sea in the capo spartivento canyon system offshore the southern coast of sardinia the sardinia cold water coral province is characterized in the nora canyon by a spectacular coral growth dominated by the branching scleractinian madrepora oculata at a depth of 380 460 m the general biohermal frame is strengthened by the common occurrence of the solitary scleractinian desmophyllum dianthus and the occasional presence of lophelia pertusa as documented by remotely operated vehicle survey this area is a hotspot of megafaunal diversity hosting among other also live specimens of the deep oyster neopycnodonte zibrowii the new coral province is located between the central mediterranean cwc provinces bari canyon santa maria di leuca south malta and the western and northern ones melilla catalan provencal ligurian canyons as for all the best developed cwc situations in the present mediterranean sea the new sardinian province is clearly influenced by levantine intermediate water which appears to be a main driver for cwc distribution and viability in this basin

a review of the structure petrology and dynamic deformation characteristics of some enigmatic terrestrial structures abstract we review three categories of enigmatic terrestrial structures that have a variety of macroscopic and microscopic dynamic deformation features the first category includes the midcontinent united states cryptoexplosion structures they are of shallow origin and illustrate the effects that might be expected from a meteorite impact on a sedimentary rock terrane the second category includes the well known vredefort and sudbury plutons or basement uplifts the lesser known precambrian basement uplifts at steen river manson and carswell and the diatreme breccia dikes at the slate islands they are of relatively deep seated origin and illustrate the effects that might be expected from deep crustal or mantle processes of an explosive nature the third category includes the large landslides in areas of crystalline rocks at koefels and langtang the dynamic deformation features at these latter locations appear to be related to high strain rate tectonic processes associated with the landslide itself we conclude that microscopic dynamic deformation features which occur in natural materials may have originated from meteorite impacts from internal explosions or from high strain rate tectonic process

geoelectrical evidence of bicontinuum transport in groundwater bicontinuum models and rate limited mass transfer rlmt explain complex transport behavior e g long tailing and rebound in heterogeneous geologic media but experimental verification is problematic because geochemical samples represent the mobile component of the pore space here we present geophysical evidence of rlmt at the field scale during an aquifer storage and recovery experiment in a fractured limestone aquifer in charleston south carolina we observe a hysteretic relation between measurements of pore fluid conductivity and bulk electrical conductivity this hysteresis contradicts advective dispersive transport and the standard petrophysical model relating porefluid and bulk conductivity but can be explained by considering bicontinuum transport models that include first order rlmt using a simple numerical model we demonstrate that geoelectrical measurements are sensitive to bicontinuum transport and rlmt parameters which are otherwise difficult to infer from direct hydrologic measurements

hot regions and the origin of marginal basins in the western pacific abstract volcanic provinces showing no genetic relationship to plate boundaries may be classified into two categories hot spots which are a few hundred kilometers across and may be nearly fixed in position with respect to deep mantle and hot regions which are a few thousand kilometers across and can migrate more freely the mantle upwellings which presumably give rise to them may originate at different depths by different causes it is observed that the marginal basins older than 15 ma of the western pacific become progressively younger northward with the exception of the south fiji basin this leads to the hypothesis that the spreading of marginal basins was caused by the mantle upwelling associated with a migrating hot region and that a hot region which started from the australia region in the late cretaceous migrated northward successively creating the tasman coral sea caroline south china parece vela shikoku and japan basins through paleocene eocene oligocene and early miocene time this hot region presently underlies northern china mongolia and adjacent areas another hot region is assumed to have caused the spreading of the south fiji basin and all the currently spreading basins in the southwestern pacific spreading of individual marginal basins occurred during the short period when a hot region was passing the pertinent area the main merit of this hypothesis is that it can explain the relationship between the location and age as well as the short duration of spreading of western pacific marginal basins marginal basins are formed commonly though not always in the overriding plates near subduction zones because in such a setting a spreading marginal basin is readily accommodated either by an oceanward movement of the nearby subduction zone or by a continentward movement and subduction of the overriding oceanic plate there are a few marginal basins that were formed in other tectonic settings and accommodated by some other mechanism of compensative subduction presumably the splitting of the supercontinent pangea was also caused mainly by the effect of the mantle upwelling associated with the same hot region that later migrated northward creating marginal basins in the western pacific the main basis for this presumption is the fact that the splitting of pangea was completed in the australia region in middle cretaceous time whereas the spreading of marginal basins in the western pacific began in the same australia region in the late cretaceous immediately following

hydrological response of weathered clay shale slopes water infiltration monitoring with time lapse electrical resistivity tomography this work presents an attempt to monitor water infiltration and subsurface flow within a clay shale landslide using time lapse electrical resistivity tomography ert a rainfall experiment was carried out on a plot of 100 m2 at the laval landslide in the draix experimental catchments ore draix south french alps in order to characterize the spatial and temporal development of water circulation in the soil and to identify when steady state flow conditions are reached the experiment was conducted during 67 h with initial unsaturated conditions in the slope the apparent electrical resistivity values were inverted with a time lapse approach using several cross models the results indicate a significant decrease in resistivity 18 compared to the initial state in the rain plot downslope progression of negative resistivity anomalies is imaged suggesting that vertical and subsurface lateral flows have developed about 21 h after the start of the rain experiment a constant level of resistivity values is observed indicating that the hydrological system reached steady state flow conditions this observation is consistent with ground water level observations and chemical tracer analysis computed differences in time of steady state conditions highlight possible preferential flows near the landslide toe a hydrological concept of functioning of the slope is proposed and apparent saturated hydraulic conductivity ks of 1 7 10 4 m s 1 is computed from the steady state times this study demonstrates the potentiality of ert monitoring to monitor water infiltration in clay shale slopes and the high water transfer capacity of reworked clay shale material

where did ancient carbonate mounds grow in bathyal depths or in shallow shelf waters abstract carbonate mounds are important and ubiquitous components of the sedimentary rock record throughout the phanerozoic nevertheless factors controlling their occurrence and growth remain enigmatic in particular because the depositional depths of such mounds are poorly constrained and it is assumed that fossil examples lack modern analogues factors currently used to constrain the water depth that ancient mounds grew in include water energy occurrence of specific organisms that perform photosynthesis particularly calcareous algae and distinct non biogenic components in reviewing the main criteria used to delineate water depth of formation of fossil carbonate mounds most if not all criteria traditionally used to assume shallow water settings appear to be no longer substantiated in the light of current knowledge gained from modern carbonate mounds high energy assumed to indicate shallow water conditions is ongoing in water as deep as 1000 m the occurrence of peloids and processes such as micritization is not diagnostic of water depth furthermore virtually none of the calcareous algae assumed to indicate the photic zone have a taxonomically granted affiliation over the last years research in the deep ocean in particular thanks to the deployment of new devices and techniques provided a good database revealing a wide distribution of modern carbonate mounds reviewing the characteristics of ancient carbonate mounds with emphasis on depositional settings and confronting the criteria used with current knowledge from sub recent and modern carbonate mounds we conclude that for many ancient mounds a bathyal origin is at least as likely as a shallow water origin this conclusion is well supported by the sedimentary records left by these modern mounds that are astonishingly similar to those seen in palaeozoic and mesozoic carbonate mounds

two bioerosion ichnofacies produced by early and late burial associated with sea level change in bioerosion as in trace fossils as a whole deeply emplaced structures have greater survival value than shallow structures that is to say tiering the relative depth to which rasping etching and boring organisms penetrate their substrate is of paramount importance for the preservation potential of individual trace fossils an entobia ichnofacies is established for trace fossil assemblages dominated by deep tier borings and arising from long term bioerosion such as occurs on sediment free submarine cliffs or hardgrounds a gnathichnus ichnofacies comprises assemblages containing all tiers including superficial sculptures produced by radulation that have very little preservation potential such assemblages occur in short term bioerosion situations as on shell surfaces and hardgrounds buried early by sedimentation

benthic habitat characterization and distribution from two representative sites of the deep water sml coral province mediterranean abstract two sites ms04 and ms06 from the santa maria di leuca sml coral province were analyzed by a video and acoustic survey during the national italian project apulian plateau bank ecosystem study aplabes site ms04 atlantis mound is characterized by a sub conical mound 500 m wide and 25 m high located at a water depth of about 650 m site ms06 yellow chain comprises several elongated reliefs nnw sse oriented up to 25 m high and 500 m in maximum lateral extent located at a depth of between 490 and 540 m at both sites two main mesohabitats mound and intermound containing several coral bearing and barren macrohabitats were observed in recorded videos and detected in side scan sonographs the coral rich macrohabitats characterized by densely packed colonies of the scleractinians madrepora oculata and secondarily lophelia pertusa m l are typically restricted to the mound areas the mud dominated ones almost devoid of m l colonies are more common within the intermound mesohabitat however on the most extensive mounds both macrohabitat typologies exist they are heterogeneously distributed on the mound surface often showing a clear differentiation along two opposite flanks of the same topographic feature m l rich macrohabitats are preferentially located on top and along the mound northeastern flank showing a typical step like distribution probably reflecting the arrangement of hard substrate outcrops along this flank fan shaped madrepora colonies and sponges are often oriented nnw sse implying together with other evidence a primary southwestern current flow the hard bottom macrohabitats of the southwestern mound flank are generally restricted to sparse exposed subvertical to overhanging scarps as well as to heterometric boulders located at the scarp base their fauna is mainly characterized by small sized organisms such as sponges and solitary scleractinians although m sized boulders may locally host very large antipatharian colonies leiopathes glaberrima the heterogeneous distribution of the observed benthic macrohabitats seems to be strictly related to the local topography the main current flow and consequently larvae food supply per unit of time and the substrate typology hard vs soft bottom

the deep structure of the central alps inferred from both geophysical and geological data gravity surveys of the past century established that mountains have roots seismic refraction lines shot in the second half of this century confirmed the downbulge of the moho under the alps and recent reflection traverses provided new details on the behaviour of crustal layers in the deep part of the alps however geophysical data are ambiguous geologically for models of the root in terms of rock distribution to be tectonophysically acceptable they must be the retrodeformable result of kinematic sequence that fits the geological surface data for a cross section through the swiss alps based on refraction data and somewhat modified by the recent reflection traverses a kinematic model compatible with large scale geological data may be obtained by the superposition of three neogene phases with alternating vergence although alpine collision is largely dextrally compressive in the central alps the n s component may be discussed in a cross section particularly puzzling geophysical features include a high velocity body in the middle crust and the disappearance of the layered foreland crust in the root in order to account for these phenomena it is proposed that the crustal root is interpreted as the result of complex reshuffling of middle and lower crustal masses as well as large scale phase transformations the mid crustal highvelocity body is interpreted as a delaminated section of the lower crust of the adria plate that was wedged into the middle crust of the alps in the middle miocene the disappearance of the foreland lower crust is attributed to eclogitization attendant on the subduction of continental crust material balance estimates suggest that during alpine collision large volumes of continental crust have disappeared through subduction

imaging high stage river water intrusion into a contaminated aquifer along a major river corridor using 2 d time lapse surface electrical resistivity tomography the hanford 300 area is located adjacent to the columbia river in south central washington state usa and was a former site for nuclear fuel processing operations waste disposal practices resulted in persistent unsaturated zone and groundwater contamination the primary contaminant of concern being uranium uranium behavior at the site is intimately linked with river stage driven groundwater river water exchange such that understanding the nature of river water intrusion into the 300 area is critical for predicting uranium desorption and transport in this paper we use time lapse electrical resistivity tomography ert to image the inland intrusion of river during high stage conditions we demonstrate a modified time lapse inversion approach whereby the transient water table elevation is explicitly modeled by removing regularization constraints across the water table boundary this implementation was critical for producing meaningful imaging results we inverted approximately 1200 data sets 400 per line over 3 lines using high performance computing resources to produce a time lapse sequence of changes in bulk conductivity caused by river water intrusion during the 2011 spring runoff cycle over approximately 125 days the resulting time series for each mesh element was then analyzed using common time series analysis to reveal the timing and location ofmore river water intrusion beneath each line the results reveal non uniform flows characterized by preferred flow zones where river water enters and exits quickly with stage increase and decrease and low permeability zones with broader bulk conductivity break through curves and longer river water residence times the time lapse ert inversion approach removes the deleterious effects of changing water table elevation and enables remote and spatial continuous groundwater river water exchange monitoring using surface based ert arrays under conditions where groundwater and river water conductivity are in contrast less

micritic cement in microborings is not necessarily a shallow water indicator abstract intragranular micritic cement has been observed in microborings from deep sea sedimentary particles pteropod shells depths 528 m to 871 m it is particularly conspicuous in depositional environments such as the blake plateau such cementation may be concurrent and analogous to the formation of intergranular deep sea cement it can occur at such energy levels where particle to particle contacts do not persist for sufficient time to allow intergranular cementation

bimodal magmatism and associated sedimentary facies with particular reference to the correlation between orogeny and regression it is stressed that a thorough investigation of the subtle and still poorly understood relationships between orogeny magmatism and associated sediments is warranted certain types of sediments appear to be commonly linked to specific magmatic contexts this is especially true for the oceanic crust but it may be equally valid for bimodal continental magmatism with the development of granite grand scale regression with the formation of continental detrital deposits could represent the response to mantle upwelling and or plume activity

spatiotemporal bioerosion patterns in deep water scleractinians from off santa maria di leuca apulia ionian sea abstract this study focuses on the carbonate biodegradation processes of deep water scleractinians from off apulia at santa maria di leuca sml in the ionian sea including living colonies of lophelia pertusa madrepora oculata and desmophyllum dianthus the corallites were grouped into three zones the live zone edge zone and dead zone in total 13 trace types were encountered and are attributed to borings of sponges 3 fungi 6 foraminifers 2 bacteria 1 and annelids 1 their relative spatial appearance within the host skeletons led to the distinction between six succession stages of bioerosion the first endobiontic traces are exclusively produced by bacteria and fungi and are already present in the edge zone which could be attributed to their fast growth rates and or temporal exposure of the bare skeleton to the water column in d dianthus the entire ichnospecies assemblage has been documented within the first 1 9 cm below the live zone and represents the most condensed bioerosion succession amongst the coral species studied the strongest degradation of corallites at sml is made by boring sponges which can excavate 70 or more of the skeleton the finding of a unilateral condensed succession of bioerosion stages may be linked to prevailing unidirectional strong currents a comparison of the present ichnocoenosis with bioerosion studies from the eastern atlantic evidences a reduced ichnodiversity in ionian sea bathyal corals

potential of electrical resistivity tomography to infer aquifer transport characteristics from tracer studies a synthetic case study 1 with time lapse electrical resistivity tomography ert transport processes in the subsurface can be imaged and monitored the information content of obtained spatiotemporal data sets opens new ways to characterize subsurface spatial variability difficulties regarding a quantitative interpretation of the imaged transport may arise from the fact that data inversion used in ert is generally underdetermined and that ert data acquisition is often limited to two dimensional 2 d image planes to address this problem we conducted a numerical tracer experiment in a synthetic heterogeneous aquifer with preset variability and spatial correlation of the hydraulic conductivity and monitored the tracer breakthrough in a 2 d image plane perpendicular to the mean flow direction using time lapse ert the tracer breakthrough patterns in the image plane were interpreted using equivalent transport models an equivalent convection dispersion equation to characterize the spatially averaged breakthrough and a stream tube model to characterize local breakthrough curves equivalent parameters derived from simulated and from ert inverted concentrations showed a good agreement which demonstrates the potential of ert to characterize subsurface transport using first order approximate solutions of stochastic flow and transport equations equivalent model parameters and their spatial variability were interpreted in terms of the local scale dispersion and the spatial variability of the hydraulic conductivity the spatial correlations of the stream tube velocity and of the hydraulic conductivity were found to be closely related consequently the hydraulic conductivity spatial correlation may be inferred from stream tube velocity distributions which can be observed with sufficiently high spatial resolution using ert

stress near the surface of the earth over most of the earth s surface earthquake hypocenters are concentrated in the depth range 0 15 km that is in the upper half of the crust chen molnar 1983 the exception is the subduction zones where cold litho sphere is underthrust to greater depths as a first approximation the top 10 15 km of the crust can be regarded as a region of nearly elastic response to stress with brittle fracture under sufficient stress difference this is the depth range discussed in this review the lower crust appears to be characterized by some form of ductile response to stress in large areas of the upper crust the stress field is related to large scale tectonic processes and represents the tractions acting on the plate concerned however some decoupled crustal blocks are known and are noted herein caution is necessary in generalizing the stress in a region to the plate that contains it recent reviews of crustal stress are given by ranalli chandler 1975 wyss 1977 mcgarr gay 1978 and gay 1980 in the upper crust one principal stress is generally within 20 of the vertical except beneath very rough topography and this vertical principal stress jz is usually within 10 of the lithostatic pressure j pg dz due to overlying rock mcgarr gay 1978 the horizontal principal stresses generally increase with depth and may be less or greater than the vertical pressure within a few hundred meters of the surface the rock mass is divided into blocks by numerous fractures including large and small faults on which shear displacements can be identified and joints on which no shear movement can be seen if the ambient stress is comparable to the strengths of these

changes in fossil assemblage in sediment cores from mingulay reef complex ne atlantic implications for coral reef build up ct scanning and descriptions of sedimentary sequences have been conducted to describe the internal structure and define the evolutionary sequence of events leading to the build up of cold water coral reef constructed by the azooxanthellate scleractinian lophelia pertusa two vibrocores containing coral clasts and associated fauna embedded in a matrix of marine sediment were taken at the mingulay reef complex an inshore 120 190 m water depth l pertusa reef off western scotland the cores were scanned using computed x ray tomography ct scan with the aim of 1 reconstructing and quantifying the relative abundance and preservation of coral fragments in the cores 2 identifying distinct reef facies and hence 3 providing data that could lead to a conceptual model of reef growth u series dates were obtained on l pertusa clasts from the two sediment cores to provide a temporal framework of the reef build up after exploring a range of methods for processing ct scans three simple parameters were used to classify different strata within the cores the overall density of the cores the number of fossil clasts and the sum of the area of clasts detected by the ct scan these parameters were validated by comparing with density measurements from a multi sensor core logger mscl and physical dissection and analysis of fossils in the cores from the ct scan analyses three distinct reef facies were evident coral rich sediment rich and shelly coral hash layers the succession and rapid cycle of reef framework forming l pertusa development disturbance and recovery allow us to provide a model of cold water coral reef build up including shifts in biodiversity physical chemical biological processes and the sedimentary regime

growth and demise of cold water coral ecosystems on mud volcanoes in the west alboran sea the messages from the planktonic and benthic foraminifera the dhaka and maya mud volcanoes mvs located in the mud diapir province in the western alboran basin along the moroccan coasts were cored during the ttr 17 leg 1 cruise cores were taken on the top of the volcanoes at a water depth of 370 m on the dhaka mv core ttr17 ms411g and at 410 m water depth on the maya mv core ttr17 ms419g respectively on both mud volcanoes the extruded mud breccia provides the nucleation point for the colonization and development of cold water corals and associated ecosystems two phases of cold water coral growth are observed 1 between slightly older than 4175 62 years bp and around 2230 59 years bp at dhaka and 2 between slightly older than 15583 185 years bp and around 7613 38 years bp at maya mv on the top of the maya mv only a small patch reef and or isolated corals proliferated whereas a more extended patch reef colonized the top of the dhaka mv at both sites the cold water coral developmentwas triggered by the availability of a suitable substrate for initial coral settling provided either as a firm ground or as single clasts subsequently coral growth was supported by enhanced nutrient flux possibly related to upwelling and or strong currents during the intervals of coral growth planktonic foraminiferal assemblages were dominated by neogloboquadrina incompta the decline of coral ecosystems on the mud volcanoes is accompanied at surface by a shift fromthe n incompta dominated assemblage to a globorotalia inflata dominated assemblage possibly reflecting more oligotrophic conditions this shift is coeval to the passage from wet to arid conditions at the end of the african humid period at mayamv it is interpreted as an effect of an early human impact on a fragile environment which was already stressed by desiccation at the time of the development of complex human society along the mediterranean coasts at dhaka mv

visualization of conduit matrix conductivity differences in a karst aquifer using time lapse electrical resistivity 1 in the karstic upper floridan aquifer surface water flows into conduits of the groundwater system and may exchange with water in the aquifer matrix this exchange has been hypothesized to occur based on differences in discharge at the santa fe river sink rise system north central florida but has yet to be visualized using any geophysical techniques using electrical resistivity tomography we conducted a time lapse study at two locations with mapped conduits connecting the santa fe river sink to the santa fe river rise to study changes of electrical conductivity during times of varying discharge over a six week period our results show conductivity differences between matrix conduit changes in resistivity occurring through time at the locations of mapped karst conduits and changes in electrical conductivity during rainfall infiltration these observations provide insight into time scales and matrix conduit conductivity differences illustrating how surface water flow recharged to conduits may flow in a groundwater system in a karst aquifer

a shallow geothermal experiment in a sandy aquifer monitored using electric resistivity tomography groundwater resources are increasingly used around the world for geothermal exploitation systems to monitor such systems and to estimate their governing parameters we rely mainly on borehole observations of the temperature field at a few locations bulk electric resistivity variations can bring important information on temperature changes in aquifers we have used surface electric resistivity tomography to monitor spatially temperature variations in a sandy aquifer during a thermal injection test heated water 48 c was injected for 70 hours at the rate of 87 l h in a 10 5 c aquifer temperature changes derived from time lapse electric images were in agreement with laboratory water electric conductivity temperature measurements in parallel a coupled hydrogeologic saturated flow and heat transport model was calibrated on geophysical data for the conceptual model and on hydrogeologic and temperature data for the parameters the resistivity images showed an upper flow of heated water along the well above the injection screens and led to a new conceptualization of the hydrogeologic source term the comparison between the temperature models derived from resistivity images and from the simulations was satisfactory quantitatively resistivity changes allowed estimating temperature changes within the aquifer and qualitatively the heated plume evolution was successfully monitored this work demonstrates the ability of electric resistivity tomography to study heat and storage experiments in shallow aquifers these results could potentially lead to a number of practical applications such as the monitoring or the design of shallow geothermal systems

flow parameters in a shallow conduit flow carbonate aquifer inner bluegrass karst region kentucky usa abstract in the carbonate aquifers which underlie most karst terrains groundwater flow is through a dendritic system of solution conduits in such aquifers termed shallow conduit flow aquifers the methods used to model granular and fracture aquifers are not generally applicable investigations were conducted in the inner bluegrass karst region of central kentucky with the objective of developing methods of modeling shallow conduit flow aquifers as well as obtaining quantitative information on a specific portion of the aquifer to assist in its management for water supply purposes in the inner bluegrass karst region groundwater basins are developed in each of which there is an integrated system of solution conduits which conducts recharge to a major spring one of the largest of these groundwater basins feeds royal spring which serves as the principal water supply for the town of georgetown the basin extends over 15 km to the southeast and most of its flow is furnished by underground diversions of cane run a surface stream with headwaters near the center of the city of lexington the principal objectives of the field investigation were to determine discharges at the spring and travel times to the spring from discrete recharge points within the basin termed swallets the spring is ungaged and an attempt was made to obtain a continuous discharge record by the dilution of dye introduced at a swallet comparison of the dye dilution discharge record with stage discharges at the spring revealed substantial discrepancies which are believed to be caused by as much as five sixths of the low flow discharge from the upper portion of the basin bypassing the spring the dye dilution method therefore provided significant insights into the geometry of the conduit system of the groundwater basin although it proved unsatisfactory as a method of determining discharges at the spring analysis of the travel times and stage discharges provided information on the conduit geometry by modeling the flow as open channel flow in a rectangular channel flow in the system is rapid ranging from 140 to 590 m h 1 although the flow rate increases with discharge the relationship is not simple owing to substantial increases in conduit cross sectional area at higher discharges flow is turbulent and subcritical under all conditions the most surprising result was the very low depth of flow calculated less than 17 cm at even the highest discharge although this must be considered an equivalent depth it is believed to indicate that active flow in shallow conduit flow aquifers is generally in a thin zone just beneath the water table

magmatism at rifted continental margins the intense volcanism and uplift observed on many rifted continental margins forming basaltic seaward dipping reflector sequences is accompanied by the emplacement of a thick igneous section at depth partial melting by decompression of passively upwelling asthenosphere that is hotter than normal because it is near a hotspot explains both the thickness of the new igneous crust and the initial elevation of the rifted margins

megafauna of vulnerable marine ecosystems in french mediterranean submarine canyons spatial distribution and anthropogenic impacts abstract vulnerable marine ecosystems vme in the deep mediterranean sea have been identified by the general fisheries commission for the mediterranean as consisting of communities of scleractinia lophelia pertusa and madrepora oculata pennatulacea funiculina quadrangularis and alcyonacea isidella elongata this paper deals with video data recorded in the heads of french mediterranean canyons quantitative observations were extracted from 101 video films recorded during the medseacan cruise in 2009 aamp comex qualitative information was extracted from four other cruises two marum comex cruises in 2009 and 2011 and two ifremer cruises in 1995 and 2010 to support the previous observations in the cassidaigne and lacaze duthiers canyons all the species fishing impacts and litter recognized in the video films recorded from 180 to 700 m depth were mapped using gis the abundances and distributions of benthic fishing resources marketable fishes aristeidae octopodidae vulnerable marine species trawling scars and litter of 17 canyons were calculated and compared as was the open slope between the stoechades and toulon canyons funiculina quadrangularis was rarely observed being confined for the most part to the marti canyon and i elongata was abundant in three canyons bourcart marti petit rhone these two cnidarians were encountered in relatively low abundances and it may be that they have been swept away by repeated trawling the lacaze duthiers and cassidaigne canyons comprised the highest densities and largest colony sizes of scleractinian cold water corals whose distribution was mapped in detail these colonies were often seen to be entangled in fishing lines the alcyonacean callogorgia verticillata was observed to be highly abundant in the bourcart canyon and less abundant in several other canyons this alcyonacean was also severely affected by bottom fishing gears and is proposed as a vulnerable marine species our studies on anthropogenic impacts show that seafloor disturbance by benthic fishing is mainly attributable to trawling in the gulf of lion and to long lines where rocky substrates are present the bauxite residue red mud expelled in the cassidaigne canyon was seen to prevent fauna from settling at the bottom of the canyon and it covered much of the flanks litter was present in all of the canyons and especially in considerable quantities in the ligurian sea where the heads of the canyons are closer to the coast three marine protected areas and one fishing area with restricted access have recently been established and should permit the preservation of these deep ecosystems

using 2d inversion of magnetic resonance soundings to locate a water filled karst conduit a new methodology for magnetic resonance sounding mrs data acquisition and interpretation was developed for locating water filled karst cavities this methodology was used to investigate the ouysse karst system in the poumeyssens shaft in the causse de gramat france a new 2d numerical mrs response model was designed for improved accuracy over the previous 1d mrs approach a special survey performed by cave divers confirmed the accuracy of the mrs results field results demonstrated that in favourable conditions a low em noise environment and a relatively shallow large target the mrs method used with a coincident transmitter receiver loop can be an effective tool for locating a water filled karst conduit it was shown numerically that because an a priori orientation of the mrs profile with the karst conduit is used in the inversion scheme perpendicular for instance any error in this assumption introduces an additional error in locating the karst however the resulting error is within acceptable limits when the deviation is less than 30 the mrs results were compared with an electrical resistivity tomography ert survey it was found that in poumeyssens ert is not able to locate the water filled karst on the other hand ert provides additional information about heterogeneities in the limestone

time lapse electrical resistivity imaging of solute transport in a karst conduit the use of electrical resistivity surveys to locate karst conduits has shown mixed success however time lapse electrical resistivity imaging combined with salt injection improves conduit detection and can yield valuable insight into solute transport behaviour we present a proof of concept above a known karst conduit in the kentucky horse park lexington kentucky a salt tracer solution was injected into a karst window over a 45 min interval and repeat resistivity surveys were collected every 20 min along a 125 m transect near a monitoring well approximately 750m downgradient from the injection site in situ fluid conductivity measurements in the well peaked at approximately 25 of the initial value about 3 h after salt injection time lapse electrical resistivity inversions show two broad zones at the approximate conduit depth where resistivity decreased and then recovered in general agreement with in situ measurements combined salt injection and electrical resistivity imaging are a promising tool for locating karst conduits the method is also useful for gaining insight into conduit geometry and could be expanded to include multiple electrical resistivity transects

high resolution bathymetry and acoustic geophysical data from santa maria di leuca cold water coral province northern ionian sea apulian continental slope abstract a total of 800 km 2 of multibeam echo sounder coverage roughly 800 km of chirp sonar data and 18 km of side scan sonar profiles 100 500 khz were acquired a few km offshore santa maria di leuca south eastern italy from 200 m to 1300 m water depth the explored area belongs to the upper slope of the gently south eastward dipping apulian continental margin northern ionian sea acoustic datasets were collected by three different oceanographic expeditions where evidence of living cold water coral cwc colonies were documented by previous surveys and samples high resolution multibeam bathymetry indicated an extensive rough seafloor with an irregular faulted upper surface to the west reflecting large scale tectonic control on the margin and a highly disrupted upper slope formed by prominent downslope mass movements to the north a broad area in the east was influenced by mass transport deposition which resulted in a very complex hummocky seafloor mainly shaped by detached block like features and failure related bedforms i e low scarps downslope lineations and compressional ridges from the shallow seismic stratigraphic data failure events appeared to be multiple and recurrent and chaotic reflectors both buried and exposed at the seafloor affected most of the investigated area drift sedimentation was also recognised along a central large ridge resulting in an interplay between contour currents and downslope turbidity currents the spatial distribution of the cwc reefs was inferred from the acoustic facies interpretation based on video images and ground truthed by sediment samples it appeared that 1 within the investigated area living coral frameworks were located along large topographic highs facing the main flow of the bottom currents where hard and firm substrata and or failure related sediment bedforms occurred 2 cwc mainly settled on clustered and isolated mound like features tens to a few hundreds of metres long and no more than 25 m high and were located between 600 and 900 m water depth within the broad area affected by downslope mass transport deposits such mound like morphologies could thus be interpreted as a result of sediment accreted by coral growth with the consequent sediment trapping on small scale positive seafloor irregularities formed by different types of pleistocene exposed mass transport deposits their burial prevented by bottom currents

right lateral shear and rotation as the explanation for strike slip faulting in eastern tibet the convergence of two continents can be accommodated by crustal thickening and by lateral transport of crust out of the path of the converging continents1 3 the principal features suggesting that lateral transport is important are major strike slip faults striking roughly orthogonally to the orientation of convergence between the continents displacement on such faults is imagined to allow lateral transport of material with respect to the converging continents possibly accounting for a large fraction of the convergence between the two continents the most spectacular example of such strike slip faulting is in the eastern part of the tibetan plateau where three major left lateral faults with slip rates of 10 mm yr 1 and several smaller roughly parallel faults dominate the regional strain field2 3 cobbold and davy4 suggested that these faults may be rotating in a clockwise fashion here we put bounds on that rate of rotation and conclude that the image of lateral transport on such faults2 known also as continental escape extrusion or expulsion is an illusion and that instead the left lateral slip on east striking planes in eastern tibet is a manifestation of north striking right lateral simple shear if this conclusion is correct the east striking left lateral faults and the crustal blocks between them are rotating clockwise at 1 2 myr 1 the east west dimension of eastern tibet is shortening at 10 20 mm yr 1 and little material is moving eastward out of india s path into eurasia by left lateral simple shear

continental tectonics in the aftermath of plate tectonics the success of plate tectonics required an acceptance of continental drift and thus a reinterpretation of the large scale geological history of most of the earth but the basic tenet of plate tectonics rigid body movements of large plates of lithosphere fails to apply to continental interiors where buoyant continental crust can detach from the underlying mantle to form mountain ranges and broad zones of diffuse tectonic activity

estimating ancient sediment fluxes original phanerozoic sediment flux rates can be approximated by fitting an exponential decay curve to the observed massjage distribution of sediments then multiplying the ratio of the observed mass to the exponential decay curve mass by the zero age flux rate predicted by the exponential decay curve applied to the massjage distribution of existing phanerozoic sediments the reconstruction method indicates that original global sediment flux rates varied cyclically by a factor of up to three this implies significant changes in the rates of uplift and mountain building and global plate tectonic activity

repeated events of hardground formation and colonisation by endo epilithozoans on the sediment starved pontine continental slope tyrrhenian sea italy abstract rock samples dredged offshore the pontine archipelago 400 2000 m water depth were studied by palaeontological analyses of planktic foraminifera and endo epilithozoan faunas colonising fe mn crusts and by petrographic analyses of volcanic samples palaeontological and petrographic analyses have revealed a complex plio pleistocene depositional history controlled by hemipelagic sedimentation and volcanic activity with episodic non depositional phases the sedimentary deposits are associated with ferromanganese hardgrounds more or less colonised by endolithic and epilithozoan organisms the presence of foraminifera typical of tropical and subtropical waters such as globigerinoides ruber globigerinoides trilobus pulleniatina obliquiloculata and sphaeroidinella dehiscens indicates that the micritic deposition occurred during warm climatic periods whilst micrite cementation and hardground formation are here attributed to colder climates the depositional processes recognised on the pontine continental slope reveal a sediment starved condition that locally resemble those of seamount environment the slope sedimentation found in the pontine archipelago can be helpful in the interpretation of ancient deposits from seamounts and continental slope depositional environments characterised by hardground and hiatuses

exhumation of high pressure metamorphic rocks the exhumation of high pressure metamorphic minerals necessitates the removal of overburden which was present at the time of metamorphism assuming metamorphism during an orogenic phase and exhumation during an uplift phase the model presented here is based on postulating continuous deformation at the active margin of an ocean continent interaction accepting the conclusion that coesite bearing eclogites and other high pressure minerals were formed when a sliver of continental crust was subducted down to 100 km i propose that their uplift was caused by a shift of the beniofff zone the high pressure slab now accreted to the continental lithosphere was lifted up the ramp of a benioff zone when ocean lithosphere was thrust under the continent the geology of the western alps illustrates this model