the heterogeneous abyss the abyssal seafloor that is ocean depths of 3 000 to 6 000 m is widely considered simply to be vast featureless plains of sediment for example wikipedia asserts that abyssal plains cover more than 50 of the earth s surface and are among the flattest smoothest and least explored regions on earth 1 featureless tracts of mud make intuitive sense since abyssal plains are formed by the deposition of thick blankets of fine grained sediments sinking from the surface ocean or transported as turbidity currents down continental margins in most of the abyss especially on seafloors 10 my old this sediment blanket is tens to thousands of meters thick 2 and seems likely to bury or smoothen most of the irregularities in seafloor crust e g basalt pillows formed at midocean spreading centers riehl et al in pnas 3 help to dispel this notion that the abyssal seafloor is featureless providing evidence of extensive rocky habitats along transform faults in the abyss scientists studying the deep sea have long known that rocky or hard substrates do occur on abyssal plains perhaps the best known are polymetallic manganese nodules that were discovered during the challenger expedition 1872 to 1876 4 nodules are widespread in the pacific abyss and to a much lesser extent the indian and the atlantic oceans 5 in some pacific regions nodules may cover 10 to 50 of the seafloor area providing abundant rocky habitat 6 7 seamounts also provide rocky substrates at abyssal depths where their slopes and outcrops are too steep to hold sediments 8 with as many as 200 000 seamounts in the world ocean seamounts too provide significant habitat area for hard bottom faunas but once again seamounts are concentrated in the pacific ocean 8 surveys with lowered cameras human occupied vehicles remotely operated vehicles and autonomous underwater vehicles 1 1email craigsmi at hawaii edu 1 xref corresp 1 1

palaeostress superimposition deduced from mesoscale structures in limestone the matelles exposure languedoc france abstract this study investigates the reasons for the superimposition of several maximum principal stress directions 1 in the same area and examines the contrast between unperturbed areas stable direction of 1 and perturbed areas changing 1 direction we studied mesoscale structures on a 1000 m2 continuous limestone exposure near a regional scale strike slip fault local 1 directions were deduced from a high concentration of minor strike slip faults extension fractures and stylolites formed during the pyrenean shortening in languedoc france most of the stylolites were formed in a stress field which was homogeneous on the exposure scale this was followed by the reactivation of pre existing extension fractures as strike slip faults whose activity determined stress perturbations a very heterogeneous stress field was produced leading to the formation of new localized stylolites and extension fractures especially at fault terminations and at oversteps thus the final pattern shows the superimposition of all these structures reactivation of structures was caused by slight temporal changes in the orientation and intensity of the stress field produced by the nearby regional strike slip faults our study suggests that the origin of stress deviations or superimpositions cannot be explained by random measurements of 1 it is essential to be able to synthesize the fault pattern and the stress trajectories which it determines and to do this a very high density or a selection of data from mesoscale structures is needed

stylolites in limestone magnitude of contractional strain accommodated and scaling relationships abstract the amount of contractional strain accommodated by a set of stylolites is analyzed by comparing the amplitudes of stylolitic teeth and spikes to independent measures of thinning of the enclosing layer the scaling relations between along strike trace length l and the maximum d max and average d avg amplitudes of stylolitic topography are also investigated the studied stylolites occur in a 212 mm thick limestone layer dragged into the damage zone of the gubbio normal fault zone in central italy layer thinning was assessed independently from the layer geometry with a maximum value of 23 nearest the fault a total of 28 mm of thinning are related to 24 stylolites whose lengths range from 6 4 to 146 mm with average amplitudes from 0 1 to 1 3 mm the average and maximum amplitudes of stylolitic topography increase with stylolite length with d avg 0 0011 l 0 17 r 2 0 57 implying propagation to greater lengths as contractional strains increase along them the stylolites increase in number and amplitude into the most thinned area correlating with increasing contractional strain accommodated by the layer the average amplitude of stylolites visible in outcrop provides a measure of the minimum magnitude of contractional strain in the rock although other mechanisms such as grain scale dissolution appear necessary to account for the remaining layer thinning

the structure of reactive grain boundaries under stress containing confined fluids we present numerical experiments on structure development in grain boundaries during dissolution precipitation creep two solids that are represented by an elastic spring configuration are pressed together with a compressible fluid in the grain boundary the solid can dissolve or precipitate depending on elastic and surface energy as well as fluid pressure and concentration of dissolved material in the fluid we perform a number of numerical experiments with different starting configurations that represent a large scale island channel interface with solid solid contacts across the islands a rough grain boundary interface with a fluid along the whole interface and a smooth thin film interface the simulations suggest that the solid solid islands become unstable by necking and anti cracking so that the island channel interface will develop into a grain boundary interface the rough interface of the grain boundary will coarsen with time so that in the extreme case a smooth thin film interface will emerge however the thin film interface is also not necessarily stable but may develop into a rough grain boundary where the roughness is initiated by heterogeneous dissolution of the solid our numerical experiments suggest that interface structures during dissolution precipitation creep are transient and that the dominance of one interface structure depends on material properties the displacement rate purity of the reacting solid and the scale of observation

the transformation of sediment into rock insights from iodp site u1352 canterbury basin new zealand abstract at integrated ocean drilling program iodp expedition 317 site u1352 east of the south island new zealand we continuously cored a 1927 m thick holocene to eocene section where we can uniquely document downhole changes in induration and lithification in siliciclastic to calcareous fine grained sediment using a wide range of petrological physical property and geochemical data sets porosity decreases from around 50 at the surface to 5 10 at the base of the deepest hole with a corresponding increase in density from 2 to 2 5 g cm 3 there are progressive bulk mineral changes with depth including an increase in carbonate and decrease in quartz and clay content grain compaction is first seen in thin section at 347 m below sea floor and intensifies downhole pressure solution chemical compaction begins at 380 m and is common below 1440 m with stylolite development below 1600 m and sediment injection features below 1680 m porewater geochemistry and petrographic observations document two active zones of cementation one shallow eogenetic down to 50 m as evidenced by micritic nodules and pore water geochemistry driven by methane oxidation by sulfate and another burial related cementation zone mesogenetic starting at 300 m a transitional zone occurs between 50 and 300 m our results quantify downhole diagenetic changes and verify depth estimates for these processes inferred from outcrop studies and provide an actualistic example of cementation and compaction trends in a slope setting

significance of fracture sets associated with stylolite zones geologic notes stylolite zones consist of an irregular seam and often a variety of associated fracture sets the geometry of this zone can be used to determine paleostress directions of the fracture sets commonly observed in close proximity to stylolites one is generally induced by the coring procedure unloading fractures and another is natural and possibly associated with stylolites of tectonic origin so called tension gashes within a unit possessing abundant stylolites the stylolites are most common in zones of relatively low porosity in addition because of the relatively compact poorly sorted fine grained nature of the seam itself stylolite zones commonly have much reduced permeability compared to the undeformed rock above and below laboratory measured permeability associated with stylolite zones can however be misleadingly large owing to the presence of unloading fractures and or tension gashes these fractures may dramatically increase laboratory permeability but commonly are either not present in the reservoir or are relevant only to the size of the laboratory measurement sample it is critical therefore to understand the origin and scale of associated fracture development in interpreting su h data

opposite vergence of a kink fold and pressure solution cleavage southeast spain a study of the relation between paleostress and fold kinematics abstract pressure solution cleavages define vergences that are opposite to those of asymmetric kink folds in limestones from the betic foreland southeast spain this cleavage fold relation is explained by an evaluation of paleostress and kinematics during kinking it is concluded that stress orientations deduced from stylolites match with models of kinking in non metamorphic rocks in this case opposite vergence of cleavage and folds is the logical consequence of the deformation mechanisms operating at different scales

late quaternary history of the mackenzie beaufort region arctic canada from modelling of permafrost temperatures 2 the mackenzie delta tuktoyaktuk coastlands in the mackenzie beaufort region maximum permafrost thickness is 750 m in the pleistocene tuktoyaktuk coastlands less than 100 m in the holocene mackenzie delta and 500 m and anomalously warm in the big lake delta plain between the two areas numerical modelling has been used to derive surface temperature histories that fit ground temperatures and permafrost conditions at 12 wells in the unipkat kumak and taglu hydrocarbon fields the models indicate that the present holocene mackenzie delta was built by fluvial processes into a submarine trough the delta front passed a site presently some 20 km from the coast about 4 5 ka and subsequently 58 m of ice bonded permafrost has aggraded in contrast the big lake delta plain was a subaerial platform for much of the wisconsinan it experienced several thousand years of inundation in the holocene probably due to widespread development of thermokarst lakes at sites 8 12 km from the coast the present subaerial conditions were established 0 5 1 5 ka throu

populations of faults and fault displacements and their effects on estimates of fault related regional extension abstract measured populations of fault displacements derived from regional seismic oilfield seismic coalmine plans and outcrop data show a power law distribution with exponents s of 0 45 to 0 95 for singleline samples across an array of faults the more negative values indicate relatively larger numbers of smaller faults an expression for a population of active faults derived from the gutenberg richter magnitude frequency relation for earthquakes is log n a b d log d where d maximum displacement of a fault n number of faults of maximum displacement d or greater and b d 1 0 and has the same value as b for the corresponding earthquake population populations of dead faults existing at the end of a tectonic episode have been numerically derived using a fault growth model and satisfy the relation log n a e log d where e has a value between 1 6 and 2 0 numerically derived populations of fault displacements in a dead fault population have slopes of s where s e 1 the contribution of an individual fault to the regional strain varies with the lifetime seismic moment of the fault and is proportional to d 2 estimation of fault related extension by summing heaves on faults of a limited size range is valid only if the measured size range of faults accommodates most of the extension correction can be made if the s value of the fault displacement population is known

simulation of surface dynamics during dissolution as a function of the surface orientation implications for non constant dissolution rates a b s t r a c t an important problem in geochemistry is the understanding of how changes occurring on a surface during dissolution affect the variability of measured dissolution rates in this study a new approach to study the effect of surface dynamics on dissolution rates is tested by coupling experimental data with a numerical model that simulates the retreat of surface profiles during dissolution we present specific results from the simulation of dissolution of fluorite surfaces the equations that determine the retreat of a surface are based on experimentally obtained equations that relate the retreat rate of a surface to a single variable the crystallographic orientation of the surface our results show that depending on the starting orientation different types of topography are developed similar to those observed experimentally during the initial dissolution phase changes of topography are rapid and associated with fast dissolution rates the progressively slower dissolution rates are coupled with the development of surface segments with orientations that dissolve at a slower rate consequently the overall retreat rate of a profile decreases during the simulation and tends to a near constant value the results show a close relationship between dissolution rates surface orientation and surface dynamics which suggests that the dissolution rate of a specific mineral phase is not constant but varies with dissolution time and surface structure this variability needs to be considered in the evaluation of experimentally derived dissolution rates future dissolution experiments and predictive kinetic models of dissolution 2014 elsevier b v all rights reserved

experimental evidence for different strain regimes of crack populations in a clay model we report results from clay extension experiments used as a model for the evolution of fault populations due to stress interactions at yielding cracks begin to appear and the brittle strain due to them quickly reaches a rate matching the applied stretching rate the crack density number of cracks per unit area initially increases apace then reaches a maximum at a critical strain decreasing thereafter at low strains where the crack population is dilute a power law length distribution is observed which at high strain gradually transitions to an exponential this agrees with fault populations data observed in low and high strain settings these results indicate that fault populations ranging from power law to exponential size frequency distributions reflect the population evolution with increased strain

recent arctic deltaic sedimentation olivier islands mackenzie delta north west territories canada despite a low tidal range and relatively low wave conditions the mackenzie delta is not prograding seaward but rather is undergoing transgressive shoreface erosion and drowning of distributary channel mouths in the olivier islands region of the mackenzie delta the resultant morphology consists of a network of primary and secondary channels separated by vegetated islands new ground is formed through channel infilling and landward directed bar accretion this sedimentation is characterized by seven sedimentary facies 1 hard cohesive silty clay at the base of primary channels which may be related to earlier offshore deposition 2 ripple laminated sand beds believed to be channel fill deposits 3 ripple laminated sand and silt interpreted as flood stage subaqueous bar deposits 4 ripple laminated or wavy bedded sand silt and clay representing the abandonment phase of channel fill deposits and lateral subaqueous bar deposition from suspension settling 5 a well sorted very fine sand bed presumed to result from a single storm event 6 parallel or wavy beds of rooted silt sand and clay interpreted as lower energy emergent bar deposits and 7 parallel or wavy beds of rooted silt and clay believed to represent present day subaerial bar aggradation the distribution of sedimentary facies can be interpreted in terms of the morphological evolution of the study area initial bar deposition of facies 3 and channel deposition of facies 2 was followed by lateral and upstream bar sedimentation of facies 3 and 4 which culminated with the deposition of the storm bed of facies 5 facies 6 and 7 signify bar stabilization and abandonment patterned ground formed by thermal contraction and preserved in sediments as small v shaped sand wedges provides the most direct sedimentological indicator of the arctic climate however winter ice and permafrost also govern the stratigraphic development of interchannel and channel mouth deposits ice cover confines flow at primary channel mouths promoting the bypassing of sediments across the delta front during peak discharge in the spring permafrost minimizes consolidation subsidence and accommodation in the nearshore further enhancing sediment bypass storms limit the seaward extent of bar development and promote a distinctive pattern of upstream and lateral island growth the effects of these controls are reflected in the vertical distribution of facies in the olivier islands the sedimentary succession differs markedly from that of a low latitude delta

development and scaling relationships of a stylolite population abstract the frequencies amplitudes and insoluble residue thicknesses of 4639 stylolites have been measured from 674 3 m of core from four vertical wells in the khuff formation a permo triassic carbonate reservoir offshore abu dhabi although there are similar numbers of stylolites per metre of core in dolomites and limestones the stylolites in the limestones have approximately double the cumulative amplitudes and insoluble residue thicknesses than the stylolites in dolomites this indicates that stylolites in the limestones have grown at approximately twice the speed or for twice as long as the stylolites in the dolomites stylolite amplitudes in dolomites and limestones together appear to obey a power law scaling relationship over about one order of magnitude 20 150 mm stylolite amplitudes in dolomites however have a higher power law exponent than those in the limestones and appear to obey a power law down to 10 mm this indicates that stylolites in the limestones have merged more than the stylolites in the dolomites the amount of pressure solution and possibly the scaling of a population of stylolites may also be controlled by location within the fold with less pressure solution in the hinge region into which hydrocarbons migrated earlier than in the limbs

a new stylolite classification scheme to estimate compaction and local permeability variations we modeled the geometrical roughening of bedding parallel mainly layer dominated stylolites in order to understand their structural evolution to present an advanced classification of stylolite shapes and to relate this classification to chemical compaction and permeability variations at stylolites stylolites are rough dissolution seams that develop in sedimentary basins during chemical compaction in the zechstein 2 carbonate units an important lean gas reservoir in the southern permian zechstein basin in germany stylolites influence local fluid flow mineral replacement reactions and hence the permeability of the reservoir our simulations demonstrate that layer dominated stylolites can grow in three distinct stages an initial slow nucleation phase a fast layer pinning phase and a final freezing phase if the layer is completely dissolved during growth dissolution of the pinning layer and thus destruction of the stylolite s compaction tracking capabilities is a function of the background noise in the rock and the dissolution rate of the layer itself low background noise needs a slower dissolving layer for pinning to be successful but produces flatter teeth than higher background noise we present an advanced classification based on our simulations and separate stylolites into four classes 1 rectangular layer type 2 seismogram pinning type 3 suture sharp peak type and 4 simple wave like type rectangular layer type stylolites are the most appropriate for chemical compaction estimates because they grow linearly and record most of the actual compaction up to 40 mm in the zechstein example seismogram pinning type stylolites also provide good tracking capabilities with the largest teeth tracking most of the compaction suture sharp peak type stylolites grow in a non linear fashion and thus do not record most of the actual compaction however when a non linear growth law is used the compaction estimates are similar to those making use of the rectangular layer type stylolites simple wave like stylolites are not useful for compaction estimates since their growth is highly non linear with a very low growth exponent in the case where sealing material is collected at the tooth during dissolution stylolites can act as barriers for local fluid flow as they intensify sealing capabilities of pinning layers however the development of teeth and spikes offsets and thus destroys continuous stylolite seams so that the permeability across the stylolite becomes very heterogeneous and they are no continuous barriers this behavior is best shown in rectangular layer and seismogram pinning type stylolites that develop efficient fluid barriers at teeth tips but destroy sealing capabilities of layers by offsetting them at the flank leading to a permeability anisotropy along 2 d stylolite planes suture sharp peak stylolites can create fluid barriers if they collect enough sealing material however if the collecting material does not seal or if spikes offset the sealing material the stylolite leaks we propose that our classification can be used to realistically estimate chemical compaction in reservoirs and gives an indication on how heterogeneous the permeability of stylolites can be

fingerprinting stress stylolite and calcite twinning paleopiezometry revealing the complexity of progressive stress patterns during folding the case of the monte nero anticline in the apennines italy in this study we show for the first time how quantitative stress estimates can be derived by combining calcite twinning and stylolite roughness stress fingerprinting techniques in a fold and thrust belt first we present a new method that gives access to stress inversion using tectonic stylolites without access to the stylolite surface and compare results with calcite twin inversion second we use our new approach to present a high resolution deformation and stress history that affected meso cenozoic limestone strata in the monte nero anticline during its late miocene pliocene growth in the umbria marche arcuate ridge northern apennines italy in this area an extensive stylolite joint vein network developed during layer parallel shortening lps as well as during and after folding stress fingerprinting illustrates how stress in the sedimentary strata did build up prior to folding during lps the stress regime oscillated between strike slip and compressional during lps before ultimately becoming strike slip again during late stage fold tightening our case study shows that high resolution stress fingerprinting is possible and that this novel method can be used to unravel temporal relationships that relate to local variations of regional orogenic stresses beyond regional implications this study validates our approach as a new powerful toolbox to high resolution stress fingerprinting in basins and orogens combining joint and vein analysis with sedimentary and tectonic stylolite and calcite twin inversion techniques

a sea level curve for the canadian beaufort shelf radiocarbon dated peat and peaty clay samples from geotechnical boreholes in the canadian beaufort continental shelf have been used to reconstruct a late quaternary relative sea level rsl curve the samples were carefully selected and evaluated using palynological techniques to ensure that reasonable age error limits could be given to each sample the dated samples were then related to the local geological setting using seismic profiles to determine the environment of deposition the resulting data show a rise of 140 m in rsl since 27 000 years bp a minor lowering of rsl at some time between 20 000 and 10 000 years bp is inferred from acoustic data contributions from basin subsidence sediment loading and consolidation account for 35 m of the total rsl rise the rsl curve is interpreted in the light of recent models of the isostatic and eustatic responses of the earth s crust at the laurentide ice sheet margin ice may have been more extensive during the middle wisconsinan than previously thought a

globsed updated total sediment thickness in the world s oceans we present globsed a new global 5 arc minute total sediment thickness grid for the world s oceans and marginal seas globsed covers a larger area than previously published global grids and incorporates updates for the ne atlantic arctic southern ocean and mediterranean regions which results in a 29 7 increase in estimated total oceanic sediment volume we use this new global grid and a revised global oceanic lithospheric age grid to assess the relationship between the total sediment thickness and age of the underlying oceanic lithosphere and its latitude an analytical approximation model is used to mathematically describe sedimentation trends in major oceanic basins and to allow paleobathymetric reconstructions at any given geological time this study provides a much needed update of the sediment thickness distribution of the world oceans and delivers a model for sedimentation rates on oceanic crust through time that agrees well with selected drill data used for comparison

fractal structure of stylolites abstract the recognition of fractal structure in stratigraphic systems is becoming increasingly widespread within the plethora of scale invariant sedimentary structures stylolites are one of the most visually suggestive of fractal form traces of stylolites viewed in vertical section have been studied by standard fourier spectral analysis and are found to possess spectra typical of 1 f fractional noises the power distribution is significantly shifted towards the low frequency end of the spectrum this red shifted spectrum is best modeled as a persistent fractional noise such noise spectra are those where successive positions along the data series in this case the trace of the stylolite are strongly positively correlated therefore stylolites are readily modeled as strongly persistent brownian trails regression of the noise spectrum shows the fractal dimension of the stylolite trace to be 1 346

prevention of carbonate cementation in petroleum reservoirs by the time a carbonate unit has been buried to the depths of most petroleum reservoirs the significant question is often not how did the pores originate but rather why are they still there preservation of porosity regardless of its origin is a consequence of one or more of the following mechanisms 1 minimal burial 2 reduced burial stress generally due to overpressured pore fluids 3 increased framework rigidity which prevents compaction 4 exclusion of pore waters by petroleum entry 5 stable mineralogy 6 permeability barriers isolating porous intervals from diagenetic fluids and 7 pore resurrection a consequence of the temporary filling of pores with cement that is subsequently removed examples from the stratigraphic record demonstrate that each of these pore preserving mechanisms may control reservoir quality

mechanics of the formation of orthogonal sets of solution seams and solution seams and veins and parallel solution seams and veins abstract commonly observed networks of pressure solution seams psss and psss and veins can be broken down to three basic assemblages orthogonal pss sets orthogonal pss vein sets and parallel pss vein sets we investigate stress distributions around psss idealized as localized volume reduction structures lvrss to identify the conditions for forming these three fundamental assemblages various geometries of lvrss are taken into account including elliptical lvrss with smooth flanks lvrss with triangular and rectangular asperities on their flanks and lvrss with overall irregular geometries such as columnar and conical shapes the modeling results indicate that if the first pss set has elliptical shapes with smooth flanks the conditions for generating the fundamental assemblages listed above are highly restrictive primarily due to relatively large average aspect ratios of psss as measured in the field which indicate lower stresses around psss as they grow however both laboratory and field observations have shown that pss surfaces are extremely rough we find that psss with relatively rough flanks and psss with overall irregular trace geometry such as sutured and zig zag or wiggly are much more favorable for generating the stresses for the formation of these fundamental structural assemblages based on a series of stress domain maps from our mechanical model we evaluated the stress strain and geometric conditions for the formation of each of the three assemblages it turns out that there are a wide variety of loading and geometric factors favoring the formation of a particular type of assemblage

stress fields about strike slip faults inferred from stylolites and tension gashes abstract in general the long axis of the tension gashes and stylolitic columns developed in limestones during a single phase of compressional deformation occur parallel to the direction of the maximum compressive stress 1 this is the case in the languedoc for structures developed in the jurassic limestones during the n s pyrenean compression exceptionnally however these microstructures turn in direction and become oblique even orthogonal one to the other probably as a consequence of a variation in intensity and direction of the stress field at the end of a microfault this mechanism also occurs in a larger scale structure involving segments of pre tectonic joints that act as en echelon microfaults in a brittle kink band equivalent to a peculiar type of potential wrench fault

quantitative analysis of stylolite networks in different platform carbonate facies abstract stylolites are rough surfaces that form by pressure solution and present variable geometries and spatial distributions despite being ubiquitous in carbonate rocks and potentially influencing fluid flow it is not yet clear how the type and distribution of stylolite networks relate to lithofacies this study investigates lower cretaceous platform carbonates in the benicassim area maestrat basin spain to statistically characterise stylolite morphology and stylolite network distributions in a selection of typical shallow marine carbonate lithofacies from mudstones to grainstones bedding parallel stylolite networks were sampled in the field to quantify stylolite spacing wavelength amplitude intersection morphology and connectivity grain size sorting and composition were found to be the key lithological variables responsible for the development of rough anastomosing stylolite networks poorly connected stylolites with large vertical spacings were found to be dominant in grain supported lithofacies where grains are fine and well sorted anastomosing stylolite networks appear well developed in mud supported lithofacies with poorly sorted clasts that are both heterogenous in size and composition mud supported facies feature stylolites that are closely spaced have high amplitudes and intersection densities and predominantly present suture and sharp peak type morphologies larger grains and poor sorting favour the formation of stylolites with small vertical spacings low wavelengths and high amplitudes this statistical analysis approach requires only limited information such as that from drill core and can be used to characterise stylolite morphology and distributions in subsurface carbonate reservoirs

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

the formation and growth of pressure solution seams in clastic rocks a field and analytical study abstract pressure solution seams psss are closing mode structures of localised dissolution resulting in a volume reduction we present new observations constraining the processes by which psss initiate and grow in low porosity clastic rocks from southern ireland psss initiate as inter granular psss at quartz grain to grain contacts as quartz dissolves clay remains as a residue along the contacts as well as filling the adjacent pores to form incipient psss involving multiple grain boundaries further lengthening and thickening occurs by lateral linkage and transverse coalescence of neighbouring segments of incipient psss multiple pss segments are observed to concentrate in thin tabular zones that appear as single macroscopic psss visible in hand samples published numerical modelling results show the ability of both lateral and transverse growth of psss due to the presence of asperities on their flanks which confirm our interpretations based on our laboratory and field observations

anisotropic scaling of tectonic stylolites a fossilized signature of the stress field 1 vertical stylolites are pressure solution features which are considered to be caused by horizontal tectonic loading with the largest principal compressive stress being sub parallel to the earth s surface in the present study we analyze the roughness of such tectonic stylolites from two tectonic settings in southern germany and northeastern spain aiming to investigate their scaling properties with respect to the stress during formation high resolution laser profilometry was carried out on opened stylolite surfaces of nine samples these data sets were then analyzed using one and two dimensional fourier power spectral approaches we found that tectonic stylolites show two self affine scaling regimes separated by a distinct crossover length l as known for bedding parallel stylolites in addition tectonic stylolites exhibit a clear in plane scaling anisotropy that modifies l since the largest and smallest crossover lengths are oriented with the sample vertical and horizontal directions i e 2 and 3 and l is a function of the stress field during formation as analytically predicted we conclude that the scaling anisotropy of tectonic stylolites is possibly a function of the stress field knowledge of this crossover length anisotropy would enable the reconstruction of the full three dimensional stress tensor if independent constraints of the depth of formation can be obtained

the geometry and petrogenesis of dolomite hydrocarbon reservoirs the wide distribution of dolomite rocks in north american middle and far eastern hydrocarbon reservoirs is reason enough for their intensive study in this volume dolomite enthusiasts review progress and define the current boundaries of dolomite research related particularly to the importance of these rocks as reservoirs as might be expected reviews provide critical analyses of past ideas on origins and why many are no longer tenable discussions range between conceptual models and numerical simulations of the flow paths of dolomitizing fluids geochemical modelling and microbial mediation case studies from areas as diverse as north america the middle east se asia and australia provide a solid background but illustrate important differences in views on the origins of these enigmatic rocks

a mechanism for development of stylolites a sequence of processes is offered by which a rock that is initially almost homogeneous could become stylolitic the host rock is assumed to contain initially a not quite uniform distribution of clay particles that have two properties when dispersed they are sites where dissolution of host rock is enhanced but when concentrated and compacted they can form a low permeability obstacle to migrating fluids initially compression is isotropic then extra compression is imposed along some single direction the first property of the clay causes initial small fluctuations in clay abundance to be self accentuating and also leads to development of contrasted layers normal to the extra compression flow of solvent parallel to these layers ultimately bifurcates because of the clay s second property thereafter to an increasing extent flow of solvent takes advantage of those portions of the clay rich seam that form the sides of stylolitic columns and are not compressed by the extra compression

the fractal geometry of some stylolites from the calcare massiccio formation italy stylolites are serrated surfaces that form by stress enhanced dissolution though their geometry and morphology reflects their formation and evolution only a few studies have attempted to quantify them here we present results indicating that stylolites in limestone of the calcare massiccio formation jurassic italy are fractal over 4 5 orders of magnitude in spatial bandwidth with an average fractal dimension obtained by spectral and scaled windowed variance analyses clustering at 1 47 some stylolites from the skene cambrian usa and tamar cenomanian israel formations are fractal over 3 orders of magnitude with fractal dimensions of 1 26 and 1 43 these values are high relative to other natural surfaces and reflect the jagged topography of the stylolites preliminary results indicate that the fractal dimension and power are constant throughout the stylolite surface and are not orientation dependent furthermore we show that stylolite contours are fractal too the grain size does not register in our analyses implying that the grain is not a cutoff between processes rather stylolite generating processes operate similarly below and above the grain size our results suggest that the geometry of these stylolites especially at long wavelengths may not be sensitive to the immediate fabric surrounding them

low stress deformation of garnet by incongruent dissolution precipitation creep abstract microstructures indicating incongruent dissolution precipitation creep of garnet in eclogite facies graphitic micaschist tauern window eastern alps are investigated garnet dissolution is observed where garnet poikiloblasts grown at eclogite facies metamorphism approached each other as a consequence of progressive deformation during exhumation with estimated p t conditions between 570 c 1 7 gpa and 470 c 0 9 gpa the poikiloblasts are separated by a dissolution seam and flanked by strain shadows filled with quartz white mica and chlorite there is no evidence for crystal plastic deformation of garnet two cases are investigated a stylolitic contact zone b smooth contact zone in both cases internal fabrics of the poikiloblasts and concentric chemical zoning are truncated material previously forming inclusions in the garnet poikiloblasts is now passively enriched in a dissolution seam the original microstructure of fine grained mica graphite aggregates remaining preserved though microstructures suggest that garnet dissolution was driven by local stress concentration the level of differential stress remained too low for plastic deformation of the fine grained white mica graphite aggregates set free from the stress supporting garnet incongruent dissolution precipitation creep appears to be a particularly effective deformation mechanism at low stress in a subduction channel

the influence of rock heterogeneity on the scaling properties of simulated and natural stylolites abstract stylolites are among the most prominent deformation patterns in sedimentary rocks that document localized pressure solution recent studies revealed that stylolite roughness is characterized by two distinct scaling regimes the main goal of the present study is to decipher whether this complex scaling behavior of stylolites is caused by the composition of the host rock i e heterogeneities in the material or is governed by inherent processes on respective scales namely the transition from a surface energy to an elastic energy dominated regime as theoretically predicted for this purpose we have developed a discrete numerical technique based on a lattice spring model to simulate the competition between stress strain and dissolution during stylolite roughening we varied systematically the quenched noise initially present in the material which controls the roughening we also changed the size amount and dissolution rate of the heterogeneities introduced in our model and evaluated the influence on the scaling exponents our findings demonstrate that the roughness and growth exponents are independent of the exact nature of the heterogeneities we discovered two coinciding crossover phenomena in space and time that separate length and time scales for which the roughening process is either balanced by surface or elastic energies our observations are consistent with analytical predictions and with investigations quantifying the scaling laws in the morphology of natural stylolites the findings presented here can further be used to refine volume loss compaction estimates from the finite strain pattern of stylolites

stress sensitivity of stylolite morphology abstract stylolites are rough surfaces that form by localized stress induced dissolution using a set of limestone rock samples collected at different depths from a vertical section in cirque de navacelles france we study the influence of the lithostatic stress on the stylolites morphology on the basis of a recent morphogenesis model we measured the roughness of a series of bedding parallel stylolites and show that their morphology exhibits a scaling invariance with two self affine scaling regimes separated by a crossover length l at the millimeter scale consistent with previous studies the importance of the present contribution is to estimate the stylolite formation stress from the sample position in the stratigraphic series and compare it to the crossover length l using the expected relationship l 2 we obtained a successful prediction of the crossover behavior and reasonable absolute stress magnitude estimates using relevant parameters depth of stylolite formation between 300 to 600 m with corresponding normal stress in the range of 10 18 mpa accordingly the stylolite morphology contains a signature of the stress field during formation and we thus suggest that stylolites could be used as paleo stress gauges of deformation processes in the upper crust

syn to late orogenic quartz veins marking a retrograde deformation path in a slate belt examples from the high ardenne slate belt belgium abstract an integrated structural petrographic and microthermometric methodology has been applied on syn to late orogenic quartz veins from the high ardenne slate belt belgium to define their relative timing the quartz precipitates which do not show any mutual cross cutting relationships represent the meso scale brittle accommodation during fold initiation amplification and locking crystal plastic deformation structures and p t trapping conditions indicate that the different processes accommodating folding occurred in a progressive manner along a retrograde deformation path associated with the gradual exhumation of the slate belt from ca 7 5 to 6 km depth successive veining occurred from peak metamorphic conditions ca 300 c and 190 mpa measured in extrados veins to subsequent lower p t conditions in the periphery of a lenticular vein ca 275 c and 180 mpa late orogenic saddle reef filling ca 245 c and 160 mpa and the core of a lenticular vein ca 220 c and 150 mpa open cavity growth and fluid assisted brecciation indicate that veining occurred under overpressured fluid conditions it is therefore fair to assume that the high ardenne slate belt acted at least episodically as a mid crustal overpressured fluid reservoir not only in the earliest and latest stages but also during the main stage of orogeny

modeling ground thermal conditions and the limit of permafrost within the nearshore zone of the mackenzie delta canada 1 this study examines the interrelated effects of snow and ice on ground thermal conditions beneath regions of shallow water within the nearshore zone of the mackenzie delta field and model based data were used to determine the thermal boundary conditions at the sediment bed surface and to define the contemporary limit of permafrost over two consecutive winters mean sediment bed temperatures deviated up to 9 8 c beneath bottom fast ice that ranged from 10 cm to 100 cm thick with intrasite variability as much as 4 7 c measured and modeled temperatures were found to exponentially relate to the duration of time ice is bottom fast with the sediment bed mean winter ground temperatures at this boundary were predicted within 0 25 c of the observed measurements using numerical thermal modeling as on ice snow depth decreased the limit of equilibrium permafrost shifted toward progressively deeper water because of longer durations of ice contact and greater heat loss from the ground the critical water depth for permafrost under equilibrium conditions was 84 cm calculated from an ice thickness of 93 cm which is equivalent to an ice contact time of 142 days equilibrium permafrost was mapped beneath 393 8 km2 of bottom fast ice an additional 387 9 km2 exhibited seasonal ground freezing in the winter of 2006 2007 areas affected by bottom fast ice represent locations that are actively receiving sediment from distributary channels these results provide the first estimates of contemporary permafrost distribution for shallow water regions of the outer mackenzie delta

bedding parallel stylolites as a tool to unravel maximum burial depth in sedimentary basins application to middle jurassic carbonate reservoirs in the paris basin france in recent years stylolites which are rough dissolution surfaces commonly found in carbonates have been used for paleopiezometry estimates the stylolite roughness inversion technique srit applied on sedimentary bedding parallel stylolites bps grants access to the maximum principal vertical stress experienced by the host carbonates and thus to their maximum burial paleo depth this study reports the results of srit applied to a bps population hosted in carbonate platform reservoirs of the paris basin sub surface france middle jurassic carbonates from two well cores from the depocenter and margin of the basin for which the burial and thermal history are known based on a thermally calibrated 3 d basin model were analyzed by defining a consistency criterion and using two signal treatment methods we propose a new approach to select which bps can be reliably used to reconstruct the maximum vertical stress undergone by the host carbonates which then can be converted into maximum burial depth the study of a bps population shows that there is a control operated by the host rock texture and the stylolite morphology on the burial depth recorded especially suture and sharp peak bps are better suited to estimate the real maximum depth whereas seismogram pinning bps record preferentially intermediate depths median values of maximum depth derived from our data set 1300 and 1650 m for the margin and depocenter cores respectively are in line with maximum burial estimates provided by conventional basin modeling 1450 and 1800 m respectively thus showing that srit is a standalone robust depth gauge in sedimentary basins provided sample selection and data treatment are carried out in a rigorous and thoughtful manner

the hydrocarbon generation potential and migration in an alkaline evaporite basin the early permian fengcheng formation in the junggar basin northwestern china abstract the permian fengcheng formation in the mahu sag in the junggar basin represents deposition in a rare alkaline saline lake with hydrologically closed conditions alkaline saline brines and intense volcanic activity the fengcheng formation contains large volumes of high quality source rocks which form not only in the depocenter but also in the wide shallow lake margins the source rocks analyzed in this study are different from those in most other ancient lakes in the following aspects genesis and occurrence of organic matter kerogen type lithological composition and hydrocarbon migration pathway this study showed that the fengcheng formation has high hydrocarbon generation potential and that combinations of multiple paths enhanced the hydrocarbon expulsion and migration benthic microbial mats and algae that bloomed in the alkaline saline lake represent the dominant types of organic matter due to their specific composition the evaporites may have catalyzed hydrocarbon generation via organic inorganic interactions while intergranular seams in bedded laminated evaporites provided paths for hydrocarbon migration stylolites with high contents of brittle minerals and low clay content also allowed favorable paths for hydrocarbon expulsion and migration combining hydrocarbon expulsion fractures in the organic rich laminae fractures and microfractures caused by compressive tectonic stress pathway networks formed that enhanced the efficiencies of both hydrocarbon expulsion and migration

growth of stylolite teeth patterns depending on normal stress and finite compaction abstract stylolites are spectacular rough dissolution surfaces that are found in many rock types they are formed during a slow irreversible deformation in sedimentary rocks and therefore participate to the dissipation of tectonic stresses in the earth s upper crust despite many studies their genesis is still debated particularly the time scales of their formation and the relationship between this time and their morphology we developed a new discrete simulation technique to explore the dynamic growth of the stylolite roughness starting from an initially flat dissolution surface we demonstrate that the typical steep stylolite teeth geometry can accurately be modelled and reproduce natural patterns the growth of the roughness takes place in two successive time regimes i an initial non linear increase in roughness amplitude that follows a power law in time up to ii a critical time where the roughness amplitude saturates and stays constant we also find two different spatial scaling regimes at small spatial scales surface energy is dominant and the growth of the roughness amplitude follows a power law in time with an exponent of 0 5 and reaches an early saturation conversely at large spatial scales elastic energy is dominant and the growth follows a power law in time with an exponent of 0 8 in this elastic regime the roughness does not saturate within the given simulation time our findings show that a stylolite s roughness amplitude only captures a very small part of the actual compaction that a rock experienced moreover the memory of the compaction history may be lost once the roughness growth saturates we also show that the stylolite teeth geometry tracks the main compressive stress direction if we rotate the external main compressive stress direction the teeth are always tracking the new direction finally we present a model that explains why teeth geometries form and grow non linearly with time why they are relatively stable and why their geometry is strongly deterministic while their location is random

rheology of the plate interface dissolution precipitation creep in high pressure metamorphic rocks abstract subduction zone models invoke deformation to be concentrated along the plate interface in a region of particularly low temperature geophysical observations do not provide constraints on temperature stress and deformation patterns with desired resolution in contrast the record of high pressure metamorphic rocks exhumed from subduction zones provides details on p t history deformation mechanisms and stress state albeit not readily correlated with the former dynamic situation on larger scale here we review available information on dissolution precipitation creep dpc in high pressure metamorphic rocks which if representative for subduction zones in general can pose constraints on conditions rheology and flow patterns along the plate interface the key observations and conclusions are that 1 deformation is typically highly inhomogeneous and localized into shear zones 2 stresses are generally too low to drive crystal plastic deformation 3 microfabrics suggest dissolution precipitation creep to be the predominant deformation mechanism 4 an aqueous fluid at quasi lithostatic pressure is available throughout allowing for tensile fracturing and crack healing or sealing 5 low stress combined with high strain rates required for localized deformation at typical subduction rates implies low viscosity and 6 contribution of shear heating to the thermal budget of subduction zones should be moderate the dominant deformation mechanism dpc is reviewed in some detail including experimental and theoretical approaches various examples of dpc in high pressure metamorphic rocks are illustrated emphasizing the role of interphase boundaries as sites of dissolution rheology governed by dpc is proposed to control interplate coupling and development of a subduction channel with return flow being a likely candidate for rapid exhumation of high pressure metamorphic rocks

modeling the growth of stylolites in sedimentary rocks stylolites are ubiquitous pressure solution seams found in sedimentary rocks their morphology is shown to follow two self affine regimes analyzing the scaling properties of their height over their average direction shows that at small scale they are self affine surfaces with a hurst exponent around 1 and at large scale they follow another self affine scaling with hurst exponent around 0 5 in the present paper we show theoretically the influence of the main principal stress and the local geometry of the stylolitic interface on the dissolution reaction rate we compute how it is affected by the deviation between the principal stress axis and the local interface between the rock and the soft material in the stylolite the free energy entering in the dissolution reaction kinetics is expressed from the surface energy term and via integration from the stress perturbations due to these local misalignments the resulting model shows the interface evolution at different stress conditions in the stylolitic case i e when the main principal stress is normal to the interface two different stabilizing terms dominate at small and large scales which are linked respectively to the surface energy and to the elastic interactions integrating the presence of small scale heterogeneities related to the rock properties of the grains in the model leads to the formulation of a langevin equation predicting the dynamic evolution of the surface this equation leads to saturated surfaces obeying the two observed scaling laws analytical and numerical analysis of this surface evolution model shows that the cross over length separating both scaling regimes depends directly on the applied far field stress magnitude this method gives the basis for the development of a paleostress magnitude marker we apply the computation of this marker i e the morphological analysis on a stylolite found in the dogger limestone layer located in the neighborhood of the andra underground research laboratory at bure eastern france the results are consistent with the two scaling regimes expected and the practical determination of the major principal paleostress from the estimation of a cross over length is illustrated on this example

active transsection faults in rift transfer zones evidence for complex stress fields and implications for crustal fragmentation processes in the western branch of the east african rift new structural and seismologic evidence from the rwenzori mountains uganda indicate that continental rifts can capture and rotate fragments of the lithosphere while rift segments interact in a manner analogous to the interaction of small scale fractures the rwenzori mountains are a basement block within the western branch of the east african rift system that is located at the intersection of two rift segments and is apparently rotating clockwise structural data and new seismological data from earthquake epicentres indicate a large scale 20 km long transsection fault is currently detaching the rwenzori micro plate on its northern margin from the larger victoria plate tanzania craton whereas it is already fully detached in the south we propose that this fault develops due to the rotation of the rwenzori block in a numerical model we show how rift segment interaction block rotation and the development of transsection faults faults that cut through the rwenzori mountains evolve through time the model suggests that uplift of the rwenzori block can only take place after the rift has opened significantly and rotation leads to the development of transsection faults that connect two rift segments so that the block is captured within the rifts our numerical model suggests that the majority of the uplift has taken place within the last 8 ma

ecology of a polymetallic nodule occurrence gradient implications for deep sea mining abyssal polymetallic nodule fields constitute an unusual deep sea habitat the mix of soft sediment and the hard substratum provided by nodules increases the complexity of these environments hard substrata typically support a very distinct fauna to that of seabed sediments and its presence can play a major role in the structuring of benthic assemblages we assessed the influence of seafloor nodule cover on the megabenthos of a marine conservation area area of particular environmental interest 6 in the clarion clipperton zone 3950 4250 m water depth using extensive photographic surveys from an autonomous underwater vehicle variations in nodule cover 1 20 appeared to exert statistically significant differences in faunal standing stocks some biological diversity attributes faunal composition functional group composition and the distribution of individual species the standing stock of both the metazoan fauna and the giant protists xenophyophores doubled with a very modest initial increase in nodule cover from 1 to 3 perhaps contrary to expectation we detected little if any substantive variation in biological diversity along the nodule cover gradient faunal composition varied continuously along the nodule cover gradient we discuss these results in the context of potential seabed mining operations and the associated sustainable management and conservation plans we note in particular that successful conservation actions will likely require the preservation of areas comprising the full range of nodule cover and not just the low cover areas that are least attractive to mining

generation of evenly spaced pressure solution seams during late diagenesis a kinetic theory stylolites and pressure solution seams can form during diagenesis of rocks subjected to stress through a feedback involving texture and pore fluid solute concentration this feedback destabilizes the state of uniform texture represented here only by porosity for simplicity a mathematical kinetic model that includes pressure solution diffusion and reprecipitation predicts the spontaneous generation even in initially uniform rocks of regions alternatingly in space more and less soluble a region that becomes more soluble also becomes simultaneously more porous the kinetic theory predicts that stylolites can form at roughly constant spacings this agrees with many field and petrographic observations bedding planes between beds that have initially different texture are shown by the theory to be the focus of a porosity instability that can lead to the formation of a stylolite and to the generation of more stylolites within each bed this prediction agrees with the observation that many stylolites have developed at bedding planes

origin and petrophysics of dolostone pore space abstract the common claim that dolomitization creates 12 porosity is based on the mole for mole replacement equation however in the past 50 years data have been collected demonstrating that dolomitization does not create porosity instead dolostones inherit the porosity and fabric of the precursor limestone and porosity is reduced by overdolomitization the porosity of the precursor limestone depends on the diagenetic history up to the time of dolomitization data show that 1 carbonates are born with high porosity and lose porosity gradually over a long period and 2 mud dominated fabrics compact more readily than grain dominated fabrics the problem of estimating the time of dolomitization is minimized by confining observations to young limestones and associated dolostones limited data from holocene dolomitic sediments suggest no change in porosity with dolomitization study of plio pleistocene carbonates in bonaire netherlands antilles demonstrates that precursor limestones are more porous than dolostones limestones average 25 porosity whereas dolostones average 11 porosity data from the neogene of the great bahama bank show that dolostones and adjacent limestones both have 40 porosity porosity studies of the jurassic arab d formation show that dolostones and associated grain dominated limestones have similar porosity ranges and that the decrease in porosity with increasing dolomitization results from compaction of the mud dominated fabrics these data suggest that porosity in dolostone is not created by a mole for mole replacement mechanism instead dolostone porosity is 1 inherited from the precursor limestone and 2 occluded by the process of overdolomitization palaeozoic dolostones however are commonly more porous than juxtaposed limestones the explanation for this observation is that limestones lose porosity through compaction and cementation whereas dolostones resist compaction and retain much of their porosity permeability studies have demonstrated that dolomitization of grain dominated limestones usually does not change porosity permeability relationships instead precursor limestone fabric controls pore size distribution the dolomite crystal size of a muddominated dolostone may however be larger than the carbonate mud size improving the porosity permeability relationship substantially hence there is a predictable relationship between interparticle grains or crystals porosity permeability precursor grain size and dolomite crystal size

the jabal akhdar dome in the oman mountains evolution of a dynamic fracture system the mesozoic succession of the jabal akhdar dome in the oman mountains hosts complex networks of fractures and veins in carbonates which are a clear example of dynamic fracture opening and sealing in a highly overpressured system the area underwent several tectonic events during the late cretaceous and cenozoic including the obduction of the samail ophiolite and hawasina nappes followed by uplift and compression due to the arabia eurasia convergence this study presents the results of an extensive tectonic survey and correlates subseismic scale structures in jabal akhdar faults fractures veins and stylolites with the main tectonic events in the northeastern arabian plate as some of the studied formations host large oil reserves in neighboring areas determining the relative timing of these events in the exhumed rocks is important to understand hydrocarbon distribution and fracture patterns in these reservoirs the formation of early veins and stylolites in the oman mountains is followed by top to the south layer parallel shearing that may be associated with the obduction of the samail and hawasina nappes this compressional tectonic event is followed by normal dip slip to oblique slip faults and veins top to the northeast layer parallel shearing which corresponds to the first stage of exhumation of the autochthonous rocks offsets these structures our new data indicate that this first phase of events is overprinted by complex strike slip networks of veins and fractures as well as by the reactivation and onset of seismic scale faults strike slip structures belong to three distinct events the first one nw se oriented compression is probably associated with the oblique collision of the indian plate against the arabian platform during the late campanian to the mid eocene the second event e w oriented compression is likely to have been formed during the late oligocene middle miocene during uplift the last event ne sw oriented compression probably took place during the miocene pliocene structures of the first two strike slip events have the same orientation as seismic scale faults observed in the subsurface of oman and abu dhabi in addition increasing vein intensity towards the top of the autochthonous formations in the oman mountains as well as the small angle between conjugate vein sets indicate that high fluid pressures that are thought to be present during strike slip deformation

discovery of widely available abyssal rock patches reveals overlooked habitat type and prompts rethinking deep sea biodiversity habitat heterogeneity and species diversity are often linked on the deep seafloor sediment variability and hard substrate availability influence geographic patterns of species richness and turnover the assumption of a generally homogeneous sedimented abyssal seafloor is at odds with the fact that the faunal diversity in some abyssal regions exceeds that of shallow water environments here we show using a ground truthed analysis of multibeam sonar data that the deep seafloor may be much rockier than previously assumed a combination of bathymetry data ruggedness and backscatter from a trans atlantic corridor along the vema fracture zone covering crustal ages from 0 to 100 ma show rock exposures occurring at all crustal ages extrapolating to the whole atlantic over 260 000 km2 of rock habitats potentially occur along atlantic fracture zones alone significantly increasing our knowledge about abyssal habitat heterogeneity this implies that sampling campaigns need to be considerably more sophisticated than at present to capture the full deep sea habitat heterogeneity and biodiversity

diagenetic implications of stylolitization in pelagic carbonates canterbury basin offshore new zealand abstract stylolites are irregular discontinuity surfaces that are thought to result from localized stress induced dissolution during burial or tectonic compression the genesis of stylolites and the controls on stylolitization are still debated and the interplay between stylolitization generation of carbonate rich fluids diagenetic fluid flow within fractures and matrix cementation and porosity modifications is complex all of these processes have important diagenetic effects potentially altering the intrinsic properties of the host rock with implications for hydrocarbon exploration and water resources in aquifers we investigate the process of stylolitization by a macroscopic petrographic and geochemical study of pressure solution features in eocene to early oligocene limestones in cores from the integrated ocean drilling program iodp hole 317 u1352c canterbury basin the results indicate correlations among stylolite amplitude stylolite density and siliciclastic content of the host rock these relationships are interpreted to suggest that siliciclastic content in carbonate rocks increases heterogeneity which in turn impacts stylolite nucleation moreover the geochemical data support that clay along the stylolite is not authigenic but a relict from impurities in the limestone host rock the statistical approach of stylolite spacing used in this study which is different than previous studies reinforces the model of random occurrence of stylolites in carbonate lithologic units this study shows that local stresses in tectonically passive areas may allow the formation of rare oblique stylolites with peaks perpendicular to the stylolite plane estimation of the amount of limestone dissolved during stylolitization minimum 7 to 12 of the depositional limestone and the volume of sparite in the host rock up to 1 6 of the compacted limestone suggests that the pressure solution fluids cemented the micropores reducing porosity to about 10 from a common porosity of about 40 in mechanically compacted chalk this study thus highlights the importance of microporosity as a sink for burial cements an observation difficult to make in thin section analysis of stylolite infills at site u1352 shows no evidence that the stylolites acted as conduits for diagenetic fluids unless if the fluid was host rock buffered and thus its chemistry indistinguishable from that of the host rock the link between siliciclastic content in carbonate rocks and the spacing and amplitude of stylolites improves understanding of burial compaction processes predicting the morphology and spacing of stylolites in the subsurface can be used to identify baffles to cross stylolite fluid flow or cementation of microporosity influencing heterogeneity of petrophysical properties in subsurface reservoir host rocks

stylolites a review abstract stylolites are ubiquitous geo patterns observed in rocks in the upper crust from geological reservoirs in sedimentary rocks to deformation zones in folds faults and shear zones these rough surfaces play a major role in the dissolution of rocks around stressed contacts the transport of dissolved material and the precipitation in surrounding pores consequently they play an active role in the evolution of rock microstructures and rheological properties in the earth s crust they are observed individually or in networks in proximity to fractures and joints and in numerous geological settings this review article deals with their geometrical and compositional characteristics and the factors leading to their genesis the main questions this review focuses on are the following how do they form how can they be used to measure strain and formation stress how do they control fluid flow in the upper crust geometrically stylolites have fractal roughness with fractal geometrical properties exhibiting typically three scaling regimes a self affine scaling with hurst exponent 1 1 0 1 at small scale up to tens or hundreds of microns another one with hurst exponent around 0 5 to 0 6 at intermediate scale up to millimeters or centimeters and in the case of sedimentary stylolites a flat scaling at large scale more complicated anisotropic scaling scaling laws depending of the direction of the profile considered is found in the case of tectonic stylolites we report models based on first principles from physical chemistry and statistical physics including a mechanical component for the free energy associated with stress concentrations and a precise tracking of the influence of grain scale heterogeneities and disorder on the resulting micro structures experimental efforts to reproduce stylolites in the laboratory are also reviewed we show that although micrometer size stylolite teeth are obtained in laboratory experiments teeth deforming numerous grains have not yet been obtained experimentally which is understandable given the very long formation time of such geometries finally the applications of stylolites as strain and stress markers to determine paleostress magnitude are reviewed we show that the scalings in stylolite heights and the crossover scale between these scalings can be used to determine the stress magnitude its scalar value perpendicular to the stylolite surface during the stylolite formation and that the stress anisotropy in the stylolite plane can be determined for the case of tectonic stylolites we also show that the crossover between medium millimetric scales and large pluricentimetric scales in the case of sedimentary stylolites provides a good marker for the total amount of dissolution which is still valid even when the largest teeth start to dissolve which leads to the loss of information since the total deformation is not anymore recorded in a single marker structure we discuss the impact of the stylolites on the evolution of the transport properties of the hosting rock and show that they promote a permeability increase parallel to the stylolites whereas their effect on the permeability transverse to the stylolite can be negligible or may reduce the permeability depending on the development of the stylolite

rift nucleation rift propagation and the creation of basement micro plates within active rifts abstract in this contribution we study the dynamics of rift nucleation and the interaction of propagating rift segments we use the east african rift system ears as a case study with special emphasis on the albertine rift system situated within the western branch of the ears with the 5000 m high rwenzori horst a basement block that was captured by two rift segments fieldwork in the rwenzori mountains shows that the range is not only affected by range parallel faults but that major fault sets cut across the rwenzoris in order to understand these complex fault patterns and the dynamics of the process that leads to the capturing of basement blocks within the extending rift system we developed a two dimensional visco elasto plastic spring model the model shows that propagating rift faults commonly capture micro plates with shapes similar to the rwenzori mountains these micro plates rotate during successive rift opening in a clockwise or anti clockwise sense depending on the direction of the rift segment overstep a left lateral overstep as is the case for the albertine rift system produces a clockwise rotation of the associated micro plate indicating that the rwenzori mountains rotate clockwise during the rotation of the micro plate the local stress field at the rift segment tips is perturbed so that the rifts turn 70 to 90 and propagate towards each other to capture the plates completely this perturbed stress field produces an extensional fault set that is oriented almost parallel to the far field extension direction and explains the range cutting faults that we find in the rwenzori mountains the large scale geometry of the rift system seems to be strongly controlled by rigid cratons in the lithosphere leading to a curvature of the western branch of the ears and a sinistral wrench component in the lake albert rift north of the rwenzori mountains capturing of micro plates of various sizes within the rift system is a common phenomenon and leads to strong perturbations of the local stress field during micro plate rotation the resulting structures are normal and strike slip faults that cut through the micro plates and local reverse faults

upper bound on stylolite roughness as indicator for amount of dissolution stylolites are rough surfaces that form by localized dissolution despite their abundance in carbonates and sandstones and their importance for fluid flow and rock deformation many fundamental issues concerning their structure and evolution are still unresolved this manuscript studies the roughening of long parallel stylolites here we report measurements of stylolite surface roughness at a scale larger than ever measured before 10 2 10 1 m measurements were performed using ground based lidar on 6 naturally exposed surfaces of 4 km long stylolites in northern israel producing a topographic map of the surfaces from which roughness characteristics were derived our results show that for length scales below 50 cm the stylolite morphology exhibits self affine behavior with a hurst exponent h 0 65 consistent with previous studies made on smaller samples the self affine behavior changes for measurements made on scales above 50 cm with h decreasing almost to zero on long length scales this observed upper bound of self affine roughness is measured here for the first time but has been previously predicted by theory ebner et al 2009b koehn et al 2007 our measurements support these theoretical models and together with them present a scenario in which the investigated stylolites evolve from preferential dissolution along an existing surface that was initially smooth and progressively roughened with time such a mechanism of stylolites growth is different from previously suggested mechanisms for other classes of stylolites which might propagate sideways from an initial defect based on the theoretical roughening model that we adopted the upper limit to fractality for this class of stylolites may be used as a measure of the amount of dissolution on stylolites indeed the amount of dissolution on the stylolites in our field site which we calculated from the upper limit to fractality is comparable to though slightly larger than our estimates of dissolution from two additional independent techniques reflecting compactive strain of 50

influence of ground ice and permafrost on coastal evolution richards island beaufort sea coast n w t a long term sediment budget 1947 1985 for northern richards island shows that when ground ice and offshore erosion are accounted for there is a near balance between headland erosion and coastal deposition excess ice constitutes about 20 of the total volume of eroded material from the headlands with massive ground ice contributing nearly 9 and segregated ice lenses and ice wedges making up the remainder coastal response to major storms in 1987 and 1993 suggests that erosion is episodic with short periods of intense disruption followed by readjustment of cliff profiles processes characteristic of this environment include mechanical erosion of ice bonded sediments creating unstable erosional niches mechanical failure of niches along ice wedge planes and longer term thermal erosion of ice bonded sediments where ice contents are high localized thaw slumps initiated by coastal erosion may retreat at rates substantially higher than those observed at other sections of the coast cliff top retreat r

late quaternary history of the mackenzie beaufort region arctic canada from modelling of permafrost temperatures 1 the onshore offshore transition five offshore drill holes northeast of richards island reveal permafrost conditions which are interpreted in terms of the sea level and paleoenviromental history of the canadian beaufort shelf the top of ice bonded permafrost lies 76 88 m below the seabed within 12 km of the shore 11 m below the seabed 20 km offshore and at 60 m some 50 km offshore the base of permafrost is 500 m to over 700 m deep temperature depth gradients are negative or nearly isothermal and permafrost is degrading geothermal modelling of the temperatures and permafrost observations indicates that the sites were subaerially exposed throughout most of the wisconsinan and during the early holocene three sites 2 10 km from the present shoreline experienced inundation at 3 5 4 0 ka these times support dates of marine transgression predicted by the sea level curve but the sites may have been occupied by thermokarst lakes prior to transgression in contrast the site 20 km offshore with shallow ice bonding was inundated about 0 4 ka this area may have persisted as an island until recently shoals observed nearby may be analogues of this process being outliers that are now being eroded below sea level marine transgression occurred about 6 ka some 50 km offshore rbsumb cinq trous de forage en mer au nord est de l ile richards rtvklent la presence de conditions de pergelisol elles sont interpr6t6es en fonction de l histoire du niveau marin et du paltomilieu de la plate forme de beaufort au canada a moins de 12 km vers le large le sommet du perg6lisol cimentk par la glace se trouve entre 76 et 88 m sous le fond marin i 20 km en mer il n est qu i 11 m sous le fond marin et a quelques 50 km en mer il passe b 60 m la

are stylolites fluid flow efficient features abstract it sounds counter intuitive to consider contraction features such as stylolites as potential conduits for flow however this idea has grown since 1980 with geoscientists finding many examples principally in carbonate reservoirs where stylolites can be considered as fluid efficient features among others these features can be reactivated stylolites can generate positive porosity and permeability anomalies can drive corrosive fluids or can remain open in an overpressured system conversely stylolites can also be closed forever these impermeable stylolites can generate permeability anisotropy that may impact fluid movements stylolites require particular attention to evaluate whether they act as drains or as barriers to flow compartmentalisation we review some of the key studies of the past thirty years with a special attention to the most recent ones we end up considering their mechanical origin their nucleation and growth their past and present impact on reservoir properties and performances as key factors influencing the flow efficiency differentiation of these features this short review presents the latest theories and observations about stylolites with respect to the key factors aforementioned the authors support herein that a distinction should be made between processes occurring in the past and the present day impact the stylolite had on reservoir properties

sedimentary stylolite networks and connectivity in limestone large scale field observations and implications for structure evolution stylolites are rough surfaces formed by localized rock dissolution and prevalent in carbonates and other sedimentary rocks their impact on porosity and permeability and capacity to accommodate compactive strain are well documented this paper presents a meso scale field study on sedimentary stylolites in carbonates characterizing large scale distributions of stylolites including measurements conducted on longer than kilometer long stylolites our field study suggests that on large scales connections between stylolites become important since connectivity and also lack of connectivity are expected to play a significant role in strain accommodation and hydraulic rock properties we suggest that large scale analysis may require a new characterization scheme for stylolites populations based on their connectivity we therefore divide sedimentary stylolite populations into three end member types which are correlated with the three possibilities for percolation of such systems isolated stylolites with zero percolation connectivity long parallel stylolites with 2 dimensional percolation connectivity and interconnected stylolite networks with 3 dimensional percolation connectivity new statistical parameters and measures are devised and used to quantitatively characterize the different population types schematic mechanistic models are then offered to explain the evolution of the three end member connectivity classes in addition we discuss the effect on fluid flow of the different population types

fault size distributions are they really power law abstract power law fault size throw distributions spanning ca seven orders of magnitude are analysed using sample lines from seismic coal mine plan and outcrop data sets outcrop data sets generally have lower power law exponent values than seismic data sets consistent with a general decrease in exponent value with decrease in fault size if such a relationship does exist then probably it cannot be accounted for by sampling bias alone we suggest that either i fault size populations are not power law over a large scale range or ii they are power law but at smaller scales show a greater range of exponent values due to spatial clustering

morphological analysis of stylolites for paleostress estimation in limestones surrounding the andra underground research laboratory site abstract we develop and test a methodology to infer paleostress from the morphology of stylolites within borehole cores this non destructive method is based on the analysis of the stylolite trace along the outer cylindrical surface of the cores it relies on an automatic digitisation of high resolution photographs and on the spatial fourier spectrum analysis of the stylolite traces we test and show on both synthetic and natural examples that the information from this outer cylindrical surface is equivalent to the one obtained from the destructive planar sections traditionally used the assessment of paleostress from the stylolite morphology analysis is made using a recent theoretical model which links the morphological properties to the physical processes acting during stylolite evolution this model shows that two scaling regimes are to be expected for the stylolite height power spectrum separated by a cross over length that depends on the magnitude of the paleostress during formation we develop a non linear fit method to automatically extract the cross over lengths from the digitised stylolite profiles results on cores from boreholes drilled in the surroundings of the andra underground research laboratory located at bure france show that different groups of sedimentary stylolites can be distinguished and correspond to different estimated vertical paleostress values for the oxfordian formation one group of stylolites indicates a paleostress of around 10 mpa while another group yields 15 mpa for the dogger formation two stylolites indicate a paleostress of around 10 mpa while others appear to have stopped growing at paleostresses between 30 and 22 mpa starting at an erosion phase that initiated in the late cretaceous and continues today this method has a high potential for further applications on reservoirs or other geological contexts where stylolites are present

divergent and convergent non isochoric deformation plane strain flow with zero elongation parallel to but widening or shortening perpendicular to the flow plane results in either divergent or convergent non isochoric deformation during this special type of flow the kinematic dilatancy number a measure of the rate at which a surface changes area with time is directly dependent on the kinematic vorticity number a measure of the rotational quality of a flow type and vice versa thus the velocity gradients tensor can be simplified being only defined by the vorticity and the instantaneous area change if these numbers can be deduced from natural deformed rocks with the help of quantitative kinematic indicators the finite deformation can be calculated if the volume change is known from independent criteria we quantitatively examine a marble mylonite from the tauern window which deformed by stress induced solution mass transfer that exhibits convergent non isochoric deformation

impact of stylolitization on fluid flow and diagenesis in foreland basins evidence from an upper jurassic carbonate gas reservoir abu dhabi united arab emirates

the permeability of stylolite bearing limestone abstract stylolites are planar features that form due to intergranular pressure solution due to their planar geometry and relative abundance in limestone reservoirs their impact on regional fluid flow has attracted considerable interest we present laboratory permeability data that show that stylolites can be considered as conduits for flow in the stylolite bearing limestones measured a combination of analysis techniques shows that this is due to a zone that surrounds these stylolites that is more porous and contains larger pores than the host rock our data also show that the water permeability of a sample containing a stylolite parallel to fluid flow is typically lower than its permeability to gas explained here as a result of the expansion of minor amounts of clay found in the stylolite and that due to their microstructural similarities tectonic and sedimentary stylolites affect sample permeability similarly finally we show that the permeability anisotropy that develops in the rock mass due to the presence of sedimentary stylolites makes it appear as though the stylolites are acting as barriers to fluid flow and may explain the discrepancy between laboratory measurements and field scale observations this approach can provide estimates for the equivalent permeability and permeability anisotropy for stylolite bearing limestone reservoirs worldwide

geoelectric observations of the degradation of nearshore submarine permafrost at barrow alaskan beaufort sea 1 submarine permafrost degradation rates may be determined by a number of interacting processes including rates of sea level rise and coastal erosion sea bottom temperature and salinity regimes geothermal heat flux and heat and mass diffusion within the sediment column observations of ice bearing permafrost in shelf sediments are necessary in order to determine its spatial distribution and to quantify its degradation rate we tested the use of direct current electrical resistivity to ice bearing permafrost in elson lagoon northeast of barrow alaska beaufort sea a sharp increase in electrical resistivity was observed in profiles collected perpendicular to and along the coastline and is interpreted to be the boundary between ice free sediment and underlying ice bearing submarine permafrost the depth to the interpreted ice bearing permafrost increases from 2 m below sea level to over 12 m below sea level with increasing distance from the coastline the dependence of the saline sediment electrical resistivity on temperature and freezing was measured in the laboratory to provide validation for the field measurements electrical resistivity was shown to be effective for detection of shallow ice bearing permafrost in the coastal zone historical coastal retreat rates were combined with the inclination of the top of the ice bearing permafrost to calculate mean vertical permafrost degradation rates of 1 to 4 cm yr 1

stylolite interfaces and surrounding matrix material nature and role of heterogeneities in roughness and microstructural development rough pressure solution interfaces like stylolites are one of the most evident features of localized slow deformation in rocks of the upper crust there is a general consensus that the development of these rough structures is a result of localized stress enhanced dissolution of material along a fluid filled interface but little is known on the initiation of this roughness the aim of this article is to reveal the role of heterogeneities initially present in the host rock on roughness initiation this should give insights on whether stylolite roughness is generated by a stress induced instability or by the presence of disorder in the material i e quenched noise we use a microstructural approach based on sem ebsd analysis combined with orientation contrast oc image analysis of stylolites in limestones we found that the stylolite roughness is induced by heterogeneities in the host rock clay particles and detrital quartz grains in our case in addition close to mature stylolite interfaces matrix modifications occur which can be attributed to the compaction along the stylolite the grain size decreases by 15 25 and a pre existing shape and lattice preferred orientation spo lpo are significantly modified in the vicinity of the stylolite the results presented here imply that localized pressure solution along stylolites is not necessarily restricted to the actual interface but influences the adjacent matrix the heterogeneity data might serve as a quantitative basis for elaborate numerical models of localized compaction

reactivity of dolomitizing fluids and mg source evaluation of fault controlled dolomitization at the benicassim outcrop analogue maestrat basin e spain abstract the mechanisms responsible for the formation of huge volumes of dolomitized rocks associated with faults are not well understood we present a case study for high temperature dolomitization of an early cretaceous aptian albian ramp in benicassim maestrat basin e spain in this area seismic scale fault controlled stratabound dolostone bodies extend over several kilometres away from large scale faults this work aims at evaluating different mg sources for dolomitization estimating the reactivity of dolomitizing fluids at variable temperature and quantifying the required versus available fluid volumes to account for the benicassim dolostones field relationships stable 13 c and 18 o isotopes as well as radiogenic 87 sr 86 sr isotopes indicate that dolomitization at benicassim was produced by a high temperature fluid 80 c 13 c and 18 o isotopic compositions for dolomite vary from 0 5 to 2 9 v pdb and from 21 1 to 24 3 v smow respectively a mg source analysis reveals that the most likely dolomitizing fluid was seawater derived brine that interacted with underlying triassic red beds and the paleozoic basement geochemical models suggest that evolved seawater can be considerably more reactive than high salinity brines and the maximum reactivity occurs at about 100 c mass balance calculations indicate that interstitial fluids with high pressure and or high temperature relative to the normal geothermal gradient cannot account for the volume of dolomite at benicassim instead a pervasive fluid circulation mechanism like thermal convection is required to provide a sufficient volume of dolomitizing fluid which most likely occurred during the late cretaceous post rift stage of the maestrat basin this study illustrates the importance of fluid budget quantification to critically evaluate genetic models for dolomitization and other diagenetic processes

morphological instabilities of stressed and reactive geological interfaces 1 interfaces between contacting rocks of the earth s crust are shown to be unstable and corrugating and develop roughness at various scales when submitted to nonhydrostatic stress this instability may occur in various geological settings as long as a coherent deformation of the interface is allowed and the bodies that the interface separates have different material properties i e viscosity density or elastic moduli relevant examples include fault planes dissolution interfaces or grain boundaries performing a two dimensional linear stability analysis we consider two cases one solid in contact with a viscous layer and two solids separated by a thin viscous layer in both cases either shear and or normal loads are imposed on the interface and thermodynamical conditions for the initiation of roughening are established applied on several geological systems such as grain contacts and fault planes we propose that our analysis can explain how complex patterns may emerge at rock rock interfaces finally we provide an analysis of the evolution of the static friction coefficient along sheared interfaces the evolution is shown to depend solely on poisson s ratio of the solid and the ratio of the shear and compressional stresses along the interface

vorticity analysis in the zagros orogen shiraz area iran quantitative vorticity analyses in orogenic belts are essential for studying the kinematics of deformation and can be performed using a range of methods the combination of microstructural analysis for vorticity with other methods creates a more rigorous analysis in order to determine the degree of non coaxiality and spatial pattern of vorticity during deformation in the zagros orogenic belt a study area containing the boundary of the zagros folded belt and the zagros fold and thrust belt is selected the study area is situated in the shiraz region of e zagros in iran the kinematic vorticity analysis is carried out using 4 methods based on 1 the degree of asymmetry of the calcite c axis fabric 2 the assumption that the orientation of the long axes of calcite within an oblique stylolite foliation delineates the direction of the instantaneous stretching axis 3 the assumption that the tension gash tips determine the direction of the instantaneous stretching axis and 4 stylolite teeth determine the direction of the instantaneous stretching axis c axis data from calcite give a kinematic vorticity number between 0 68 and 0 83 and the orientation of the long axes of calcite grains yields a range between 0 5 and 0 84 stylolites provide a kinematic vorticity number between 0 5 and 0 79 and tension gashes provide a kinematic vorticity number between 0 56 and 0 81 this range of vorticity numbers confirms the contributions of both simple 33 59 and pure shear 41 67 twining of calcite also reveals that the last stage of deformation occurred at a temperature of 170 200 c spatial analysis reveals an increase in the simple shear component from the sw of the zagros folded belt to the ne of the zagros fold and thrust belt

variety of stylolites morphologies and statistical characterization of the amount of heterogeneities in the rock the surface roughness of several stylolites in limestones was measured using high resolution laser profilometry the 1d signals obtained were statistically analyzed to determine the scaling behavior and calculate a roughness exponent also called hurst exponent statistical methods based on the characterization of a single hurst exponent imply strong assumptions on the mathematical characteristics of the signal the derivative of the signal or local increments should be stationary and has finite variance the analysis of the measured stylolites shows that these properties are not always verified simultaneously the stylolite profiles show persistence and jumps and several stylolites are not regular with alternating regular and irregular portions a new statistical method is proposed here based on a non stationary but gaussian model to estimate the roughness of the profiles and quantify the heterogeneity of stylolites this statistical method is based on two parameters the local roughness h which describes the local amplitude of the stylolite and the amount of irregularities on the signal m which can be linked to the heterogeneities initially present in the rock before the stylolite formed using this technique a classification of the stylolites in two families is proposed those for which the morphology is homogeneous everywhere and those with alternating regular and irregular portions 2006 elsevier ltd all rights reserved

temperature changes and thaw of permafrost adjacent to richards island mackenzie delta n w t thawing of ice bonded sediment below the sea floor accompanies sea level rise and shoreline retreat along the beaufort sea coast the rate of thaw is primarily controlled by the warm spring and summer discharge of the mackenzie river which affects sea bottom temperatures to water depths of 10 20 m the intensity of the warming at any one location decreases with depth until continuous sub 0 c temperatures are encountered sea level rise eventually brings the sea floor into the cold sea water zone and thawing stops therefore thawing is also controlled by the residence time in the warm zone sedimentation or scouring can respectively slow or accelerate the increase in water depth and thereby modify the rate of thaw progression this combined with changes in the rate of coastal retreat can produce a subbottom frost table with considerable relief in the extreme ice bonding within a few metres of the sea floor can be explained by accelerated submergence

stylolite controlled diagenesis of a mudstone carbonate reservoir a case study from the zechstein_2_carbonate central european basin nw germany this study was developed within the framework of dgmk german society for petroleum and coal science and technology project 718 funded by the companies exxonmobil production deutschland gmbh gdf suez e p deutschland gmbh rwe dea ag and wintershall holding gmbh the authors would like to acknowledge exxonmobil production deutschland gmbh that kindly provided core data elliot humphrey thanks the natural environment research council nerc centre for doctoral training cdt in oil gas for a phd grant egr acknowledges agaur agencia de gestio d ajuts universitaris i de recerca for a beatriu de pinos research project additional funding was provided by the generalitat de catalunya government 2017sgr 824 and the spanish government projects cgl2015 66335 c2 1 r cgl2015 69805 p and pgc2018 093903 b c22 we acknowledge theresa straub and simon gast for their assistance during core data collection we would like to thank miroslaw mirek slowakiewicz and an anonymous reviewer for their critical and constructive comments together with the editorial guidance of edoardo perri

compaction of porous rock by dissolution on discrete stylolites a one dimensional model 1 compaction of sedimentary porous rock by dissolution and precipitation is a complex deformation mechanism that is often localized on stylolites and pressure solution seams we consider a one dimensional model of compaction near a thin clay rich stylolite embedded in a porous rock under the assumption that the clay enhances solubility the model predicts a reactive transport away from the clay layer followed by pore cementation the evolution of the porosity reactant transport and compaction rate are studied as functions of model parameters and shown to reach a stationary state we find good agreement between the porosity distribution predicted by the model and previously reported field measurements the model provides quantitative estimates for compaction rates on stylolitic surfaces

recent and future trends in paleopiezometry in the diagenetic domain insights into the tectonic paleostress and burial depth history of fold and thrust belts and sedimentary basins paleopiezometry provides an access to the past stress magnitude key to better understand the behaviour of the earth s crust over long period of time this contribution presents a review of some paleopiezometric techniques that can be used in the diagenetic domain in fold and thrust belts and sedimentary basins calcite twinning and stylolite roughness techniques have been selected and are presented through a critical description of their methodologies along with approaches to further reconstruct the complete effective stress tensor major geological lessons learned over the past decades from published studies are summarized and discussed along with a way forward to potential breakthroughs

quasi flexural folding of pseudo bedding the disharmonic outcrop scale folds and associated structures in a 300 m thick cretaceous limestone formation in the pindos group exposed on mount lykaion arcadia greece can be understood only in the context of superposed pre tectonic and tectonic mass transfer dissolution creep though the structures described may seem unusual they are undoubtedly abundant in strongly deformed pseudo bedded limestone formations in this example the thick white limestone beds twlb formation displays pervasive flaggy pseudo bedding which is a diagenetic stylolitic layering resulting from pressure dissolution the mass transfer dissolution creep that produced the diagenetic stylolitic surfaces was achieved during gravitational loading accompanying burial compaction and lithification and was driven by high stress concentrations at grain contacts the diagenetic stylolitic surfaces are lined with insoluble residue and commonly are marked by interlocking stylolite teeth oriented perpendicular to the pseudo bedding at the outcrop scale individual pseudo beds display significant thickness variability moreover the individual pseudo beds not uncommonly wedge out and disappear laterally over very short distances along with all the pindos group strata the twlb formation was profoundly shortened in the late cretaceous and early tertiary as a result of inversion tectonics the pindos group limestone dominated formations underlying and overlying twlb readily accommodated flexural slip folding for these formations are marked by optimum mechanical stratigraphy ubiquitous thin bedding and pervasive bedding plane slip surfaces for the twlb formation however strain accommodation by flexural slip kinematics was spotty and inefficient primarily because individual diagenetic stylolite surfaces are by no means planar or smoothly curviplanar they tip out over short distances and their interlocking stylolite teeth create elevated frictional resistance to layer parallel slip these factors plus the apparent ease with which the limestone pseudo beds deform by tectonically induced mass transfer dissolution creep were responsible for the distinctive structures observed in outcrop these include indentation structures where a part of one fold limb indents into the other or where the hanging wall of a small thrust indents into its footwall or where the limbs of a common anticline or syncline migrate toward one another by pressure dissolution removal of the axial trace region in terms of the overall progressive deformation tectonically driven layer parallel shortening of pseudo beds first resulted in tectonic stylolites perpendicular to pseudo bedding with teeth parallel to pseudo bedding this was superseded at the mesoscopic scale by a layer parallel shortening achieved by buckling of pseudo beds with loci of buckling and incipient buckling geometries influenced primarily by pseudo bed thickness and variations in same wedge outs of pseudo beds and the mechanical properties of the pseudo beds in some cases shortening and tightening of buckle folds involved flexural slip kinematics accommodated in part by slip or shear along clayey insoluble residue at pseudo bed contacts where diagenetic stylolite surfaces abruptly tipped out or where friction along them was excessively high the slip deficit and thus shortening deficit was replaced by mass interpenetration of pseudo beds stylo faulting stylo duplexing and other forms of mass transfer dissolution creep slip toward the tip lines of wedge outs even may have produced end loading that in turn generated adjacent localized buckle folds the properties of the folds and associated structures in the twlb formation are introduced here as a new category of quasi flexural folds in the donath and parker 1964 classification