on late miocene to recent vertical motions in the cretan segment of the hellenic arc abstract high resolution foraminiferal and calcareous nannoplankton biostratigraphy and reliable paleobathymetry estimates based on plankton benthos ratios in foraminifera make it possible to reconstruct in detail late neogene vertical motions along the central cretan segment of the hellenic arc these motions are considered to express the surficial effect of the roll back process of the hellenic subduction zone which started about 12 ma ago in contrast to earlier views there is no sustained uplift since the late middle miocene successive paleotopographic profiles for central crete show a predominance of subsidence coupled with an increase of differential reliefs from the latest serravallian until the messinian subsidence was most pronounced between the tortonian messinian boundary interval and the early part of the early pliocene locally up to a magnitude of more than 1000 m a two phased uplift history coupled with tilting to the north or northeast can be inferred from the late early pliocene recent record separated by a short early late pliocene episode of subsidence rates of uplift were highest in the early pliocene up to about 125 cm ka the central cretan late neogene to recent paleotopographic profiles are compared with those reconstructed from seismic interpretations and drilling data from the cretan sea the combined results show that paleotopographic configurations between the cyclades and crete were fairly similar to those on central crete until messinian time foundering of the cretan basin started in the course of the early pliocene but subsidence rates were less than the contemporaneous uplift rates of crete the timing and magnitude of the vertical motions along the cretan sea central cretan transect put detailed geological constraints on tectonophysical modelling of the surficial effects of the roll back process these vertical motions are discussed in view of the model of southward translation of a large supracrustal slab resulting in the origin of the cretan sea and in thrusting and uplift in the frontal parts of the slab where it thrusted over the northern limb of the subducted ionian plate

coastal uplift on active normal faults the eliki fault greece the eliki fault forms part of a system of major normal fault segments that borders the southern margin of the gulf of corinth half graben radiocarbon dating of elevated marine fossils reveals broadly uniform holocene coastal uplift at a time averaged rate of 1 5 mm yr both along the eliki fault and in the transfer zone that separates it from the neighbouring fault segment coseismic uplift increments are considered to account for only a minor part of the 6 m of emergence recorded here in the last 3000 years reappraisal of shoreline data from the perachora peninsula at the eastern end of the gulf of corinth indicates a similar though less rapid 0 7 mm yr pattern of uniform holocene emergence as these holocene coastal records embody both coseismic and interseismic deformation they can be used to characterise long term tectonic strain

spectrum of pore types and networks in mudrocks and a descriptive classification for matrix related mudrock pores matrix related pore networks in mudrocks are composed of nanometer to micrometer size pores in shale gas systems these pores along with natural fractures form the flow path permeability network that allows flow of gas from the mudrock to induced fractures during production a pore classification consisting of three major matrix related pore types is presented that can be used to quantify matrix related pores and relate them to pore networks two pore types are associated with the mineral matrix the third pore type is associated with organic matter om fracture pores are not controlled by individual matrix particles and are not part of this classification pores associated with mineral particles can be subdivided into interparticle interp pores that are found between particles and crystals and intraparticle intrap pores that are located within particles organic matter pores are intrap pores located within om interparticle mineral pores have a higher probability of being part of an effective pore network than intrap mineral pores because they are more likely to be interconnected although they are intrap om pores are also likely to be part of an interconnected network because of the interconnectivity of om particles in unlithifed near surface muds pores consist of interp and intrap pores and as the muds are buried they compact and lithify during the compaction process a large number of interp and intrap pores are destroyed especially in ductile grain rich muds compaction can decrease the pore volume up to 88 by several kilometers of burial at the onset of hydrocarbon thermal maturation om pores are created in kerogen at depth dissolution of chemically unstable particles can create additional moldic intrap pores

shale gas transport model in 3d fractal porous media with variable pore sizes abstract a model for gas transport in shale is proposed by accounting for three major fluid flow mechanisms in shale stratum which is modeled as a 3d fractal media the proposed apparent permeability of shale is an analytical expression that also accounts for heterogeneous pore sizes in shale stratum and is verified using experimental datasets for methane and helium flow in shale results of sensitivity analysis indicate that surface diffusion of adsorbed gas plays an important role specifically in smaller pores while surface diffusion would be negligible in larger pores further the proposed model shows that flow due to surface diffusion decreases moderately with the increase of isosteric adsorption heat while it increases significantly with the increase of the maximum adsorption capacity one of the key novelties of the proposed permeability model is that it accounts for pore size distribution to reveal novel insights on gas transport in shale that can be used to optimize gas production by operational controls e g controlling reservoir pressure as flow regimes change with time

pore structure and fractal characteristics of organic rich shales a case study of the lower silurian longmaxi shales in the sichuan basin sw china abstract shales from the lower silurian longmaxi formation in the sichuan basin are among the most important shale gas reservoirs in china and have been investigated because of their great shale gas potential to understand the pore structure and fractal characteristics of the shales a series of experiments was conducted on core samples from the lower silurian longmaxi formation in the sichuan basin of china including x ray diffraction xrd total organic carbon toc content and vitrinite reflectance ro analysis field emission environmental scanning electron microscope fe esem observation and low pressure n 2 adsorption desorption experiments frenkel halsey hill fhh method was applied to calculate fractal dimensions in addition the pore genesis the relationships between composition and thermal maturity the pore structure parameters and the fractal dimensions are discussed fe esem observation results show that the longmaxi formation shales are dominated by organic matter om pores along with interparticle interp pores intraparticle intrap pores and fracture pores this study identified the fractal dimensions at relative pressures of 0 0 45 and 0 45 1 as d 1 and d 2 respectively d 1 ranged from 2 60 to 2 71 and d 2 ranged from 2 71 to 2 82 d 1 was typically smaller than d 2 indicating that the smaller pores in shales were more homogeneous than the larger ones the formation of these om pores is owing to kerogen deformation during the thermal maturation which results in a large number of nanopores the pore structure of the longmaxi formation shales is primarily controlled by toc content and thermal maturity toc content is a controlling factor on the fractal dimensions as it exhibited positive correlations with d 1 and d 2 fractal dimensions are useful for the characterization of the pore structures complexity of the longmaxi formation shales because d 1 and d 2 correlate well with pore structure parameters as they both increase with the increase of surface area and the decrease of average pore diameter

a comparison of 103 105 year uplift rates on the south alkyonides fault central greece holocene climate stability and the formation of coastal notches 1 measurements of holocene coastal notch sequences exposed in the footwall of the active south alkyonides normal fault greece reveal 3 holocene paleoshorelines near the lateral fault tip rising in elevation eastward toward the center of the fault where a 4th paleoshoreline appears the implied eastward increase in holocene uplift rate mirrors that for an uplifted quaternary marine terrace 0 29 mm yr 0 55 mm yr from west to east assuming these uplift rates were constant through the holocene notch elevations predict ages of 650 1900 3700 and 6500 years b p comparable with published 14 c ages on notch fauna and well correlated with periods of relatively stable holocene climate we propose that the notch sequences formed when post glacial sea level rise became outpaced by the coastal uplift rate whilst individual notches formed when stable climate facilitated sustained erosion the parity of the holocene and quaternary uplift rates suggests that notch sequences could be used to characterize long term patterns of uplift slip rate and seismic hazards on active normal faults if 6500 years is long enough to fully characterize temporal variation in the seismic cycle citation cooper f j g p roberts and c j underwood 2007 a comparison of 10 3 1 0 5 year uplift rates on the south alkyonides fault central greece holocene climate stability and the formation of coastal notches geophys res lett 34 l14310

organic matter clay mineral intergranular pores in the lower cambrian lujiaping shale in the north eastern part of the upper yangtze area china a possible microscopic mechanism for gas preservation abstract gas shales with a high gas content were encountered in the lower cambrian lujiaping formation in the northeast part of the upper yangtze area china in this area the tectonic condition is complex and the organic matter is over matured so conventional oil and gas exploration have not previously been considered during a recent shale gas exploration canister desorbed gas contents of more than 1 m 3 t were detected from 490 to 825 m depth with a maximum value of 3 18 m 3 t at 762 m hence to understand the mechanism of preservation of the gas is important the gas shales have a total organic carbon toc content of between 0 44 and 6 91 and vitrinite like macerals reflectance r o between 3 3 and 4 3 with type ii kerogen the porosity of 22 gas shale samples ranges between 0 4 and 2 29 and their permeability is between 6 9 10 5 and 3 8 10 1 md to investigate the shale s pore structure and its relation to gas storage behavior we studied the microscopic mechanism of gas preservation using a combination of pore characterization techniques including focused ion beam scanning electron microscope fib sem imaging and comparison of gas sorption and free gas storage capacity folding thrusting and subsequent rapid uplifting movements occurred after most of the dry gas had been originally generated and the present gas is a mixture originated from the cracking of liquid hydrocarbons at high maturity and kerogen pyrolysis in the early hydrocarbon generation phase sem observations combined with low temperature gas adsorption and mercury injection capillary pressure analyses show that pores within the organic matter or the mineral particles in the lujiaping shale are rare while the nanometer sized pores 1 4 nm between organic matter and clay mineral particles especially in cleavage domains are greatly developed thus the gas in these shales is mainly adsorbed gas due to the limited free gas storage space this is unlike most other shale gas reservoirs pores within the organic matter and pores between or within mineral particles are dominant moreover the desorbed gas content correlates well with toc content and the microporous and mesoporous specific surface area determined by low temperature co 2 and n 2 respectively suggesting that the nanometer sized pores associated with the organic matter make up the fundamental storage space for this shale the calculations based on fib sem observation showed that the nanometer sized intergranular pores have large specific surface areas with their small pore throat diameters resulting in high capillary pressure these characteristics have contributed to the preservation of shale gas in this complex tectonic area

laboratory characterization of the porosity and permeability of gas shales using the crushed shale method insights from experiments and numerical modelling gas production from shale resource plays has transformed the usa energy market despite the knowledge gained from the analysis of large amounts of shale core appraisal of shale gas resource plays requires a large number of wells to be drilled and tested ideally core analysis results would provide an indication of both the gas filled porosity and permeability of shale resource plays which could then be used to reduce the number of wells needed during appraisal a combination of laboratory experiments numerical modelling and a round robin test have been conducted to assess the validity of the crushed shale method csm which has been widely used in industry to assess the porosity and permeability of shale the results suggest that the csm can provide reasonably precise estimates of porosity measured at ambient stress if a standard sample cleaning method is adopted although a reliable method to correct these values to subsurface conditions needs to be developed the csm does not however appear to provide useful information on shale permeability a round robin test shows that differences of up to four orders of magnitude in permeability were provided by different laboratories when analysing the same sample these huge differences seem to occur due to a combination of errors in calculating permeabilities from pressure transients differences in the way that permeability is calculated as well as uncertainties regarding the effective size of crushed shale particles however even if standardized the csm may not be particularly useful for characterizing the flow capacity of shale because it is insensitive to the presence of high permeability zones that would control flow in the subsurface

coastline retreat via progressive failure of rocky coastal cliffs despite much research on the myriad processes that erode rocky coastal cliffs accurately predicting the nature location and timing of coastline retreat remains challenging and is confounded by the apparently episodic nature of cliff failure the dominant drivers of coastal erosion marine and subaerial forcing are anticipated to increase in the future so understanding their present and combined efficacy is fundamental to improving predictions of coastline retreat we captured change using repeat laser scanning across 2 7 104 m2 of near vertical rock cliffs on the uk north sea coast over 7 yr to determine the controls on the rates patterns and mechanisms of erosion for the first time we document that progressive upward propagation of failure dictates the mode and defines the rate at which marine erosion of the toe can accrue retreat of coastline above this is a failure mechanism not conventionally considered in cliff stability models propagation of instability and failure operates at these sites at 10 yr time scales and is moderated by local rock mass strength and the time dependence of rock fracture we suggest that once initiated failure propagation can operate ostensibly independently to external environmental forcing and so may not be tightly coupled to prevailing subaerial and oceanographic conditions our observations apply to coasts of both uniform and complex lithology where failure geometry is defined by rock mass strength and structure and not intact rock strength alone and where retreat occurs via any mode other than full cliff collapse

estimating permeability of shale gas reservoirs from porosity and rock compositions it is challenges for effectively estimating the permeability of shale gas reservoirs by traditional models however the study on this area is lacked and deficient we proposed a method for predicting permeability of shale gas reservoirs from porosity and rock compositions including mineralogy and organic matter content which is applicable to laboratory data and downhole measurements first two sets including 38 samples from the longmaxi formations were tested for porosity permeability grain density total organic carbon toc content mineralogical compositions and low temperature nitrogen adsorption we used the kozeny s equation to calculate the specific surface area which was viewed as the effective specific surface in shale formations through comparing with the specific surface from low temperature nitrogen adsorption further the effective specific surface was found to be positively correlated with clays pyrite and toc contents while negatively with quartz feldspar and carbonates then an

new empirical relationships among magnitude rupture length rupture width rupture area and surface displacement source parameters for historical earthquakes worldwide are compiled to develop a series of empirical relationships among moment magnitude m surface rupture length subsurface rupture length downdip rupture width rupture area and maximum and average displacement per event the resulting data base is a significant update of previous compilations and includes the additional source parameters of seismic moment moment magnitude subsurface rupture length downdip rupture width and average surface displacement each source parameter is classified as reliable or unreliable based on our evaluation of the accuracy of individual values only the reliable source parameters are used in the final analyses in comparing source parameters we note the following trends 1 generally the length of rupture at the surface is equal to 75 of the subsurface rupture length however the ratio of surface rupture length to subsurface rupture length increases with magnitude 2 the average surface displacement per event is about one half the maximum surface displacement per event and 3 the average subsurface displacement on the fault plane is less than the maximum surface displacement but more than the average surface displacement thus for most earthquakes in this data base slip on the fault plane at seismogenic depths is manifested by similar displacements at the surface log linear regressions between earthquake magnitude and surface rupture length subsurface rupture length and rupture area are especially well correlated showing standard deviations of 0 25 to 0 35 magnitude units most relationships are not statistically different at a 95 significance level as a function of the style of faulting thus we consider the regressions for all slip types to be appropriate for most applications regressions between magnitude and displacement magnitude and rupture width and between displacement and rupture length are less well correlated and have larger standard deviation than regressions between magnitude and length or area the large number of data points in most of these regressions and their statistical stability suggest that they are unlikely to change significantly in response to additional data separating the data according to extensional and compressional tectonic environments neither provides statistically different results nor improves the statistical significance of the regressions regressions for cases in which earthquake magnitude is either the independent or the dependent parameter can be used to estimate maximum earthquake magnitudes both for surface faults and for subsurface seismic sources such as blind faults and to estimate the expected surface displacement along a fault for a given size earthquake

tidal notches in mediterranean sea a comprehensive analysis abstract recent works evelpidou et al 2012 suggest that the modern tidal notch is disappearing worldwide due sea level rise over the last century in order to assess this hypothesis we measured modern tidal notches in several of sites along the mediterranean coasts we report observations on tidal notches cut along carbonate coasts from 73 sites from italy france croatia montenegro greece malta and spain plus additional observations carried outside the mediterranean at each site we measured notch width and depth and we described the characteristics of the biological rim at the base of the notch we correlated these parameters with wave energy tide gauge datasets and rock lithology our results suggest that considering the development of tidal notches the consequence of midlittoral bioerosion as done in evelpidou et al 2012 is a simplification that can lead to misleading results such as stating that notches are disappearing important roles in notch formation can be also played by wave action rate of karst dissolution salt weathering and wetting and drying cycles of course notch formation can be augmented and favoured also by bioerosion which can in particular cases be the main process of notch formation and development our dataset shows that notches are carved by an ensemble rather than by a single process both today and in the past and that it is difficult if not impossible to disentangle them and establish which one is prevailing we therefore show that tidal notches are still forming challenging the hypothesis that sea level rise has drowned them

heterogeneity of intergranular intraparticle and organic pores in longmaxi shale in sichuan basin south china evidence from sem digital images and fractal and multifractal geometries abstract previous studies have determined many types of pores in shale such as organic pores inorganic pores and microfractures in this study pores are classified as intergranular intraparticle and organic pores based on the location of their occurrence the heterogeneities of the three pore types and their effects on the occurrence of shale gas which is of utmost practical importance for shale gas exploration and development are discussed in this study the three types of pores are quantitatively characterized using fractal and multifractal methods the mean fractal dimension and mean width of the multifractal spectrum of these pores are found to be different i e 1 5985 and 1 665 for intraparticle pores 1 5869 and 1 475 for intergranular pores and 1 6 and 1 3725 for organic pores intraparticle pores have the highest heterogeneity intergranular pores have intermediate heterogeneity and organic pores have the lowest heterogeneity sem images show that organic pores have good connectivity homogeneous distribution and small range of aperture change but have the lowest heterogeneity even where pores are abundant thus they provide the largest shale gas occurrence space in contrast intergranular pores are less abundant have lower connectivity and have higher heterogeneity than organic pores thereby providing a relatively smaller shale gas occurrence space finally intraparticle pores are the least abundant and possess the poorest connectivity largest range of aperture change and highest heterogeneity of the three pore types thereby providing the smallest shale gas occurrence space we conclude that organic pores are crucial to the occurrence of shale gas and can provide a new index for the evaluation of shale gas exploration and development

a late pleistocene holocene lacustrine record from lake manas zunggar northern xinjiang western china information on the late quaternary palaeoclimate in the zunggar desert northern xinjiang is deduced from the study of three 5 m long cores taken from lake manas analyses including the mineralogical composition of bulk sediments stable isotope contents of carbonates organic matter pollen and diatoms were performed to help reconstruct the environmental evolution of the area the chronology is provided by 9 ams 14c dates done on carbonates or organic matter the record suggests a late pleistocene humid episode radiocarbon dated at 37 000 32 000 yr b p this episode is followed by a period of extreme aridity attributed to the last glacial maximum the early mid holocene record indicates conditions generally wetter than today as previously established for western china however our results show that the holocene period is rather complex after a minor wet warm pulse estimated to be around 12 000 yr b p the most important environmental change is recorded at 10 000 yr b p it led to the establishment of a steppic vegetation cover in the catchment and of a permanent lake which lasted 4000 years fluvial sedimentation took place between about 6000 and 4500 yr b p and it coincided with a decrease in moisture availability for vegetation growth a second lacustrine episode is recorded from about 4500 to 2500 yr b p although the pollen record and a sudden influx in detrital organic matter suggest a short term dry event around 3800 3500 yr b p the last 2500 years show climate unstability and the step wise establishment of hypersaline conditions in lake manas the major post glacial environmental changes appear to be roughly in phase with those observed in tibet

lateral propagation of the surface trace of the south alkyonides normal fault segment central greece its impact on models of fault growth and displacement length relationships abstract the evolution of deformed marine terraces and drainage systems have been examined in order to investigate the growth and lateral propagation of an active normal fault geological mapping has revealed three distinct raised marine terraces in the immediate footwall of the western end of the active south alkyonides fault segment safs gulf of corinth central greece we correlate these terraces with sea level highstands at 125 240 and 330 ka using elevation estimates of the inner edges of the terraces we show that uplift rates decrease towards the perachora fault segment boundary at the western end of the safs analysis of terraces and drainage wind gaps in the footwall of the fault shows that the surface trace of the safs propagated westwards at a rate of 12 1 16 7 mm y over at least the last 330 ka whilst the surface trace length has increased analysis of the geometry and kinematics of fault slip suggests that fault length at depth has remained fixed implying progressive increase in the values for the displacement length ratio if this is correct growth is not self similar and fault length has been established early in the evolution of the system i e before 330 ka

innovative tidal notch detection using tls and fuzzy logic implications for palaeo shorelines from compressional crete and extensional gulf of corinth tectonic settings abstract tidal notches are a generally accepted sea level marker and maintain particular interest for palaeoseismic studies since coastal seismic activity potentially displaces them from their genetic position the result of subsequent seismic events is a notch sequence reflecting the cumulative coastal uplift in order to evaluate preserved notch sequences an innovative and interdisciplinary workflow is presented that accurately highlights evidence for palaeo sea level markers the workflow uses data from terrestrial laser scanning and iteratively combines high resolution curvature analysis high performance edge detection and feature extraction based on the assumptions that remnants such as the roof of tidal notches form convex patterns edge detection is performed on principal curvature images in addition a standard algorithm is compared to edge detection results from a custom fuzzy logic approach the results pass through a hough transform in order to extract continuous line features of an almost horizontal orientation the workflow was initially developed on a single distinct and sheltered exposure in southern crete and afterwards successfully tested on laser scans of different coastal cliffs from the perachora peninsula this approach allows a detailed examination of otherwise inaccessible locations and the evaluation of lateral and 3d geometries thus evidence for previously unrecognised sea level markers can be identified even when poorly developed high resolution laser scans of entire cliff exposures allow local variations to be quantified edge detection aims to reduce information on the surface curvature and hough transform limits the results towards orientation and continuity thus the presented objective methodology enhances the recognition of tidal notches and supports palaeoseismic studies by contributing spatial information and accurate measurements of horizontal movements beyond that recognised during traditional surveys this is especially useful for the identification of palaeo shorelines in extensional tectonic environments where coseismic footwall uplift only 1 2 to 1 4 of net slip per event is unlikely to raise an entire notch above the tidal range

improved estimation of mineral and fluid volumetric concentrations from well logs in thinly bedded and invaded formations abstractcalculation of mineral and fluid volumetric concentrations from well logs is one of the most important outcomes of formation evaluation conventional estimation methods assume linear or quasi linear relationships between volumetric concentrations of solid fluid constituents and well logs experience shows however that the relationship between neutron porosity logs and mineral concentrations is generally nonlinear more importantly linear estimation methods do not explicitly account for shoulder bed and or invasion effects on well logs nor do they account for differences in the volume of investigation of the measurements involved in the estimation the latter deficiencies of linear estimation methods can cause appreciable errors in the calculation of porosity and hydrocarbon pore volume we investigated three nonlinear inversion methods for assessment of volumetric concentrations of mineral and fluid constituents of rocks from multiple well logs all three of these methods accounted for the gen

tidal notches a sea level indicator of uncertain archival trustworthiness abstract in this paper after a short summary on the processes and rates of bioerosion that contribute to the deepening of a tidal notch profile some mediterranean case studies are presented where a tidal notch is prevented either from forming or from being preserved furthermore as shown also in a complementary paper the recent global sea level rise is preventing the development of new tidal notches in the present mid littoral zone this very useful sea level indicator of past temporary standstills of the relative sea level in carbonate rock areas is of great value in assisting interpretations of relative sea level change in locations where it is preserved the possibilities of absence of formation or of preservation however imply that it should be interpreted carefully before reconstructing local relative sea level histories in particular the lack of fossil tidal notches cannot be relied upon to interpret the absence of past periods of relative sea level stabilization

active faulting within the offshore western gulf of corinth greece implications for models of continental rift deformation discrimination between different lithospheric extension models focusing on the roles of low angle vs high angle faulting and how strain is distributed requires high fidelity imaging of brittle deformation high resolution seismic reflection and multibeam bathymetric data in the western gulf of corinth continental rift were collected to establish the contribution of offshore faults to extension onshore fault slip here is significantly less than expected from geodetic strain rates the rift at this location is a half graben tilted to the north by s dipping faults within the uppermost crust a basement horst on the northern margin is uplifted by the north and south eratini faults and the axial channel is fault controlled subsided lowstand shorelines in the hanging wall of the north eratini and the well studied aigion fault suggest that the faults have similar displacements summed extension from the four major faults across this part of the rift eliki subchannel south eratini north eratini is 8 16 mm yr thereby reconciling geologic and geodetic data sets distributed deformation across isolated multiple faults can model this part of the rift without recourse to and potentially incompatible with an underlying low angle detachment

disruption of the hellenic arc late miocene extensional detachment faults and steep pliocene quaternary normal faults or what happened at corinth 1 extensional faults exposed in the peloponnesus and mainland greece most of which are described here for the first time record a transition from regional extension of the aegean domain to the modern tectonic system the east peloponnesus detachment system trends north northwest from the southern peloponnesus to 30 km north of the gulf of corinth dips gently northeast and is late miocene early pliocene in age it has a minimum displacement of 25 30 km and appears to be the youngest of the regional scale extensional systems with significant displacement that formed parallel to the hellenic arc the partially coeval east sterea extensional system which extends from the gulf of corinth to the aegean sea contains low angle normal faults that both crosscut and trend parallel to older structures of the hellenic arc late miocene to early pliocene displacement within this zone disrupted the arc parallel structures of the hellenides upper pliocene quaternary normal faults which trend approximately east west and generally dip steeply at the surface continue the disruption of the hellenic arc much of the subsidence within the gulf of corinth appears to be unrelated to the younger faults and is instead related to the motion on the east peloponnesus detachment which crosscuts the modern graben

the 8 5 magnitude ad365 earthquake in crete coastal uplift topography changes archaeological and historical signature abstract an up to 9 m uplift of western crete a cluster of coastal uplifts in the east mediterranean radiocarbon dated approximately 1500 bp as well as historical and archaeological data are evidence for major although poorly documented seismic destruction on a nearly mediterranean scale in the 4th to 5th c ad including the destruction of the nile delta in egypt by a tsunami in ad365 these data represent parts of a puzzle for historians archaeologists geologists and seismologists detailed analysis of geological historical and archaeological data including precise numismatic evidence permits recognition of a major earthquake in crete responsible for coastal uplift at ad365 elastic dislocation analysis of coastal uplift data reveals that this earthquake was associated with a reverse fault offshore of southwestern crete that its minimum magnitude was 8 5 and that this model is consistent with the available seismological and large scale tectonic data despite its magnitude this earthquake cannot have produced the necessary short period high energy waves which are necessary to explain the seismic damage which occurred circa ad365 in a very broad region from sicily to cyprus and libya hence the ad365 earthquake sequence included at least two other major events with epicentres close to cyprus and sicily although significant changes in the coastal morphology widespread destruction and a high human death toll occurred the ad365 crete earthquake was not responsible for any major cultural change it occurred during the transition from the roman to the christian period characterized by vast luxurious villas and modest dwellings on crete respectively

bicyclic alkanes in source rocks of the triassic yanchang formation in the ordos basin and their inconsistency in oil source correlation abstract the triassic yanchang formation is the main source rocks for mesozoic oil in ordos basin the formation includes 10 oil bearing beds ch 1 ch 10 that each can be further divided into two to three intervals abundant c12 c14 and c15 c16 bicyclic alkanes have been detected in the formation in the xifeng oilfield ordos basin the c12 c14 group is dominated by c12 and c13 and the c15 c16 group contains abundant c15 the groups show three distribution patterns a the c12 c14 group is the major component in the non source rocks of the ch 7 1 and ch 8 1 intervals b both groups are abundant and are common in source rocks of the ch 7 3 interval and c the c15 c16 group is the major component in source rocks of the ch 7 3 interval and also in sediments that contain type or partial sapropel type 1 organic matter om in the ch 7 2 and ch 8 1 intervals although thermal maturities of the source rocks in the ch 7 section are similar they show significant differences with respect to the drimane isomerisation index which indicates that the drimane rearrangement is controlled by thermal evolution of the sediments but may also be closely related to the depositional environment this study determined that reducing environments are more conducive to preservation of drimane than oxic environments the drimane isomerisation index and the value of the hopane parameter tm ts are positively correlated the parameter tm ts varies over a wide range within the sequence and the large variations may be a result of terrigenous om input by turbidity currents and or gravity flows mixed with the autochthonous sediments abundant homodrimane in both source rocks may reflect reducing environments in deep lakes and major input of higher plant om organic rich shale and oil shale in the ch 7 3 interval of the yanchang formation are the primary sources of oil in reservoirs in the xifeng area the crude oil is rich in bicyclic alkanes that are dominated by c15 c16 as source rocks with pattern c for bicyclic alkanes which indicates an origin mainly from the ch 7 3 interval the main peaks in all of the crude oils are associated with 8 h drimane and lower abundance of rearranged drimane however most of the source rocks have a main peak associated with 8 h homodrimane or rearranged drimane weak microbial action selective degradation and water washing may be the cause of the significant difference in bicyclic sesquiterpane composition between the crude oil and the source rocks the result suggests that oil source correlations based on the bicyclic sesquiterpanes are questionable

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

abrasive notches along the atlantic patagonian coast and their potential use as sea level markers the case of puerto deseado santa cruz argentina patagonia argentina is a key area for the study of sea level changes in the southern hemisphere but the availability of reliable sea level markers in this area is still problematic in fact the storm deposits beach ridge commonly used here to reconstruct past sea level oscillations introduce a wide error along the puerto deseado coast santa cruz morphometric analyses of 11 features were carried out using traditional measurement tools and a digital software based method tested on one selected feature with the aim to investigate the possibility of their use as sea level markers by undertaking accurate topographic profiles we identified the relationship between notches and current sea level in detail we identified two clusters of notch retreat point elevations with a very low internal variability the lower was located a little below the mean high tide level mht and the upper located at least 0 5 m above the maximum high tide level mht field observations of tidal levels and the position of notches suggest that the lower notches are active and the upper are inactive this study on the abrasive notches attests their quality as sea level markers and opens up the use of fossil abrasive notches as palaeo sea level markers because the error linked to these features is substantially smaller than that introduced by beach ridges commonly used in the study area copyright 2014 john wiley sons ltd

localization of quaternary slip rates in an active rift in 105 years an example from central greece constrained by 234u 230th coral dates from uplifted paleoshorelines mapping dating and modeling of paleoshorelines uplifted in the footwall of the 1981 gulf of corinth earthquake fault greece ms 6 9 6 7 are used to assess its slip rate history relative to other normal faults in the area and study strain localization the 234u 230th coral ages from cladocora caespitosa date uplifted shoreface sediments and paleoshorelines from glacioeustatic sea level highstands at 76 possibly 100 125 175 200 216 240 and 340 ka uplifted quaternary and holocene paleoshorelines decrease in elevation toward the western tip of the fault exhibiting larger tilt angles with age showing that uplift is due to progressive fault slip since 125 ka uplift rates varied from 0 25 to 0 52 mm yr over a distance of 5 km away from the fault tip tilting was also occurring prior to 125 ka but uplift rates were lower because the 125 ka paleoshoreline is at 77 of the elevation of the 240 ka paleoshoreline despite being nearly half its age comparison of paleoshoreline elevations and sedimentology with the quaternary sea level curve shows that slip rates increased by a factor of 3 2 0 2 at 175 75 ka synchronous with cessation of activity on a neighboring normal fault at 382 112 ka we suggest that the rapid localization of up to 10 15 mm yr of extension into the narrow gulf 30 km wide resulted from synchronous fault activity on neighboring faults followed by localization rather than sequential faulting with consequences for the mechanism controlling localization of extension

estimating permeability of carbonate rocks from porosity and vp vs we present a method for predicting permeability from sonic and density data the method removes the porosity effect on the ratio vp vs of dry rock and it addresses the specific surface as an indirect measure of permeability we look at ultrasonic data porosity and the permeability of 114 carbonate core plugs in doing so we establish an empirical relationship between the specific surface of the solid phase as calculated by kozeny s equation and vp vs linearly transformed to remove the porosity effect one must view the specific surface derived by using kozeny s equation as an effective specific surface because kozeny s equation only holds for homogeneous rock with interconnected pores the ratio vp vs of dry rocks on the other hand seems to be controlled by the true specific surface pointing to an inherent limitation in the method the 114 carbonate plugs originate in three geological settings and comprise 83 calcitic and 31 dolomitic samples their depositional texture varies from mud do

fractal analysis of tight shaly sandstones using nuclear magnetic resonance measurements assessing quantitatively the microscopic pore structures of porous rocks including irregularities of pore shapes and pore size distributions is becoming one of the most challenging efforts nuclear magnetic resonance nmr measurements were used to provide insights into the pore geometry pore size and shape and pore connectivity of the chang 7 tight shaly sandstones in situ permeability 0 1 md in ordos basin the incremental transverse relaxation time t2 distributions for the 100 brine saturated samples display unimodal and bimodal behaviors presenting a geometrical arrangement composed of small to large pore size domains the nmr parameters such as bulk volume irreducible bvi capillary and clay bound water free fluid index ffi movable water the value of t2 separating the bvi from ffi the amplitude weighted mean on a logarithmic scale t2gm and the value of t2 that shows the highest frequency on the t2 spectrum t2peak for each sample were determined then the fractal theory was adopted to quantitatively express the complexity and heterogeneity of the sandstones the results show that only minor primary intergranular porosity remains and variable amounts of micropores and secondary intragranular porosity with poor connectivity occur in the chang 7 tight shaly sandstones assuming spherical pores a new model to calculate the fractal dimension of pore structure from the nmr t2 distributions is proposed the fractal dimensions of all the samples are calculated and the accuracy of the proposed model is verified by the regression coefficients the microscopic pore structures are heterogeneous in these tight sandstones according to the high value of fractal dimensions micropores are the primary causes of heterogeneity in tight sandstones and samples with unimodal t2 distribution behaviors and high content of short components have the highest fractal dimension and heterogeneity the calculated fractal dimension is strongly correlated with t2peak and t2gm therefore the fractal model proposed in this study can be used to calculate the fractal dimensions and evaluate the heterogeneities of the porous rocks satisfactorily the fractal model proposed in this study helps to quantitatively assess the pore structures of tight sandstones using nmr measurements

a new method for estimating total organic carbon content from well logs with the booming exploration and development of unconventional hydrocarbon resources in source rocks the estimation of total organic carbon toc content from well logs has become increasingly important because of the significance of toc in the formation evaluation of those resources in this paper a new log overlay method is developed to estimate the toc content of source rocks with excess radioactivity but containing little or no potassium feldspar specifically on the basis of previous results of log responses of source rocks it is believed that the natural gamma ray gr log responses of source rocks in the applicable conditions are predominantly contributed by clay minerals and organic matter a practical clay indicator is established to reflect the clay content using density and neutron logs the indicator is effective not only in nonsource rocks that contain oil or water but also in source rocks furthermore a new method was developed by overlaying the properly scaled clay indicator curve on the gr curve in nonsource rocks including clay rich rocks and reservoirs saturated with oil or water the two curves overlie each other whereas a separation between the curves occurs in organic rich source rocks the separation between the curves was defined and expressed and can be used to calculate the toc consecutively after careful calibration with core data this method has been successfully applied to two shale gas plays with high maturity kerogen in the sichuan basin china in addition a source rock with low maturity kerogen was used to verify the new method for its effectiveness reliability and widespread adaptability

holocene coastal notches in the mediterranean region indicators of palaeoseismic clustering abstract marine tidal notches are developed by bioerosion in the intertidal zones of rocky coasts but a combination of sea level change and crustal movements can result in them being raised above or submerged below the water line for that reason the present day elevation of these former shorelines relative to the mean sea level has long been used to quantify relative coastal uplift and subsidence in tectonically active areas assuming that the sea level eustatic change component is known along the microtidal mediterranean littoral it is generally assumed that notches develop during relative stillstands of sea level when tectonic and eustatic trends are in unison and that discrete notch levels record abrupt shoreline changes caused by local seismic displacements recently however a climatic model for notch formation has been proposed in which stable periods of holocene climate favour enhanced erosion in this competing model the rate of sea level rise is lower than the tectonic uplift rate and individual notches are not specific seismic indicators because marine notches are widely used as geomorphic markers of tectonic and in some cases palaeoseismic movements a reappraisal of the geological significance of these strandlines is warranted in this paper we explore the two conflicting notch models using a database of eastern mediterranean palaeoshorelines although we conclude that the spatial and temporal distribution of the notches supports a dominantly tectonic control on notch genesis as a result of earthquake clustering we highlight how the diachronous timing of notch development tempers their value as tectonic markers

quaternary evolution of the corinth rift and its implications for the late cenozoic evolution of the aegean summary we present geological and morphological observations at different scales to constrain rates of faulting and the distribution of deformation in the seismically active aegean region we focus first on the 130 km long corinth rift an asymmetric graben where a flight of terraces of marine origin are uplifted we show that the edges of the terraces lie in the footwall of the normal fault bounding the corinth rift and correspond to sea level highstands of laic pleistocene age using a detailed analysis of aerial and spot imagery supported by field observations we have mapped 10 terrace platforms and strandlines ranging in elevation from 10 to 400 m over distances of 2 to 20 km from the fault the elevation of the terraces inner edges was estimated at 172 sites with an error of 5m this data set contains a precise description of the uplift and flexure of 10 different palaeohorizontal lines with respect to the present sea level to date the deformation we correlate the corinth terraces with late pleistocene oxygen isotope stages of high sea level stands and with global sea level fluctuations using a thick elastic plate model consistent with our current understanding of the earthquake cycle and a boundary element technique we reproduce the geometry of the shorelines to constrain both mechanical parameters and the slip on the fault we show that the seismogenic layer behaves over the long term as if its elastic modulus were reduced by a factor of about 1000 all the terraces are fitted for fault slip increasing in proportion to terrace age and the component of regional uplift is found to be less than 0 3 mm yr 1 the best fits give a slip rate of 11 3 mm yr 1 on the main rift bounding fault over the last 350 kyr other geological and morphologic information allows us to estimate the total age of the main fault 1 ma and to examine the mechanical evolution of the corinth rift the minimum observed sediment thickness in the gulf places an extreme check on the results of the modelling and a lower bound on slip rate of 6 7 mm yr 1 40 per cent less than estimated with modelling even this slip rate is nearly 10 times higher than for comparable features in most of the aegean and elsewhere in the world at a larger scale the spacing and asymmetry of the rift systems in the aegean suggest strain localization in the upper mantle with slow extension starting 15 myr ago or earlier the more recent 1 myr rapid phase of rifting in corinth partly reactivated this earlier phase of extension the younger faulting in corinth appears to result from its present location in the inhomogeneous stress field process zone of the south westward propagating tip of the southern branch of the north anatolian fault we extend these relations to propose a mechanical model for the late cenozoic evolution of the aegean as the arabia europe collision progressed in eastern turkey it caused anatolia to move to the west and the north anatolian fault to propagate into the aegean where the early slow extension started to be modified about 5 ma ago the process of propagation dramatically increased the activity of some but not all of the earlier rifts the model we present is compatible with tectonic observations as well as with the seismicity the palaeomagnetic rotations and the displacement field now observed with gps and slr

coastal notches their morphology formation and function deep coastal notches develop through undercutting of steep coastal slopes consisting of rocks that are strong enough to support the weight of the overburden notches are found from the tropics to the poles and in a wide range of rock types virtually tideless to megatidal seas and high to low wave energy environments the emphasis in the literature has been on notches in calcareous rocks in warm microtidal seas and with the general assumption that they have been produced by bioerosion or chemical dissolution few scientifically rigorous attempts have been made to determine the processes responsible for notch formation in different environments and rock types however or to determine whether different processes produce distinct notch morphologies within the same tidal and wave environments the use of notches as palaeo sea level markers and to determine rates of tectonic uplift has been particularly important in the mediterranean notches are more difficult to employ for this purpose in the middle latitudes where higher waves and tides amplify the range of elevations over which the erosional mechanisms are effective as well as increasing the exposure and effect of rocks of variable resistance to erosion to maximize the utility of notches as sea level markers and to better understand and model their development in a wide range of environments we need to understand and be able to quantify the relationship between notch shape and size and the elevational efficacy of the various erosional processes

marine notches in coastal cliffs indicators of relative sea level change perachora peninsula central greece abstract in several sites in the complex faulted western part of perachora peninsula central greece three principal marine notches in rocky coasts are present in each site no holocene notches occur above the upper of the three notches only subaerial weathering affected the rocks lateral variation in the heights of notches demonstrates differential uplift due to fault control and illustrates the complexity of application of marine notches in interpretation of tectonic history the lower undated notch is prominent in places coincides with modern sea level and is interpreted to be forming now it suggests that the western part of the peninsula has been stable for a considerable time the middle and upper notches vary in height between sites and may not be time equivalent but represent earlier sea level positions in the harbour adjacent to the heraion archaeological site the middle and upper notches are preserved in most places as notch roofs so that gradual uplift led to removal of notch floors by physical chemical and biotic processes in exposed locations however within a few hundred metres west of the harbour four uplifted plus a fifth forming now notches have been illustrated by pirazzoli et al tectonophysics 229 1994 201 that cannot be readily correlated to the harbour site and indicate differential uplift by fault displacement in a more complex situation at mylokopi 6 km ne of heraion three different notch profiles occur in three blocks separated by two faults however within the central block of the three two very different profiles are preserved only tens of metres apart beneath one continuous upper notch roof at the same height this complex arrangement interpreted as variability of exposure to marine processes on different parts of this irregular embayment such that one profile containing three notches was controlled largely by abrasion and formed notches that are vertically more extensive while the other profile containing five narrow notches formed by dissolution and or biological erosion at the same time in the protected east end of the block however if only one or the other profile was visible very different tectonic interpretations would result the bedrock of perachora peninsula also shows important variations in resistance to erosion affecting the resulting notch profiles and some sites are influenced by structurally controlled differential subaerial weathering forming ridges and grooves giving the false impression of extra minor notches the distinction between dissolution controlled and structure controlled minor notches may not be possible in some places the interpretations of notch profiles can be highly complex and influence views of tectonic history in a given region overall the occurrence of three principal notches beneath one uplifted notch roof in several sites indicates that a holocene uplift rates outpaced post glacial sea level rise b there were three principal periods of relative sea level stillstand affecting the perachora peninsula and c uplift of the entire western part of the perachora peninsula is an important component of its tectonic processes probably more important than fault movement within the peninsula

corinth rift margin uplift new evidence from late quaternary marine shorelines 1 new evidence for uplift of the southern margin to the corinth rift one of the world s most rapidly extending continental regions defines an area of uniform uplift separating a more rapidly uplifting western rift flank from a slowly backtilting eastern flank this major tectonic boundary coincides with geophysical evidence for a junction between flat underlying subducted oceanic plate and steep subduction we propose that trench rollback by the anatolian plate over the subducting african plate has led to differential uplift and possible migration of active faulting at the southern rift margin in the last few million years

reprint of bedrock fault scarp history insight from t lidar backscatter behaviour and analysis of structure changes abstract this paper provides a research approach and develops a methodology that helps natural weathered bedrock fault scarps to be understood in terms of their structural changes and backscatter behaviour when using terrestrial laser scanning t lidar we tested our approach on the pisia fault in greece that ruptured during the 1981 alkyonides earthquake sequence in corinth gulf the method describes how to correlate fault geometry and structural variations with the backscatter signal of t lidar data from naturally exhumed bedrock fault scarps using this method we are able to reconstruct the past slip history we used t lidar for the analysis of the monochromatic laser beam s backscattered signal to define unsupervised classes of unknown objects on fault surface seven classes were created based on the dendrogram technique using the maximum likelihood method these were used to determine their spatial distribution throughout the scarp height and to calculate the terrain ruggedness index tri in the defined classes the combination of these results shows that i the ruggedness increases with the scarp height and ii the ruggedness and backscattering describe different fault plane conditions we found evidence for past earthquakes on the pisia fault at our study site with average displacements in the range of 30 60 cm with corresponding magnitudes of 6 4 6 6 0 1 ms these results help to reconstruct the recent fault history and potential palaeo events and can also be used i to detect appropriate sample sites on the fault plane for absolute dating and ii as an independent constraint on tracing slip events assisting absolute dating techniques this method can significantly reduce the sampling requirements and costs of cosmogenic absolute dating techniques overall it might be a valuable tool for extracting data regarding the faulting history and slip events for defining seismic hazard parameters

eastern mediterranean tectonics and tsunami hazard inferred from the ad 365 earthquake historical accounts describe an earthquake and tsunami on 21 july ad 365 that destroyed cities and drowned thousands of people in coastal regions from the nile delta to modern day dubrovnik the location and tectonic setting of this earthquake have been uncertain until now here we present evidence from radiocarbon data and field observations that western crete was lifted above sea level by up to 10 m synchronously with the ad 365 earthquake the distribution of uplift combined with observations of present day seismicity suggest that this earthquake occurred not on the subduction interface beneath crete but on a fault dipping at about 30 within the overriding plate calculations of tsunami propagation show that the uplift of the sea floor associated with such an earthquake would have generated a damaging tsunami through much of the eastern mediterranean measurement of the present rate of crustal shortening near crete yields an estimate of 5 000 yr for the repeat time of tsunamigenic events on this single fault in western crete but if the same process takes place along the entire hellenic subduction zone such events may occur approximately once every 800 yr in the year ad 365 an earthquake and tsunami destroyed much of the eastern mediterranean coastal regions the distribution of uplift at the time suggests that the earthquake occurred on a fault within the overriding plate at the subduction zone beneath crete and not on the subduction interface itself

normal faulting and crustal deformation alkyonides gulf and perachora peninsula eastern gulf of corinth rift greece geophysical structural geochronological and geomorphological data indicate that the psatha east alkyonides skinos and pisia faults are holocene active structures whereas the status of the west alkyonides strava perachora and loutraki faults is less certain we see no evidence for significant lateral surface fault growth new data for late pleistocene footwall uplift of the psatha fault are comparable with previously estimated holocene rates pre holocene stratigraphic sequences in the alkyonides gulf allow calculation of vertical displacement on the skinos fault of 1 42 1 60 km over a period of 0 6 ma previous palaeoseismological studies indicate comparable displacement rates extrapolated to 0 61 2 20 ma whereas extrapolation of previous geodetic data indicate a range of 0 17 0 46 ma the latter is too short given the evidence of the stratigraphic record signifying either that these data may not be representative of longer term rates or that significant deformation has taken place elsewhere for example on offshore antithetic faults a case is established for uniform late quaternary post mis 7 uplift of the perachora peninsula at rates of c 0 2 0 3 mm a 1 the lack of regional tilting over perachora corinth isthmia is in marked contrast to the situation in the alkyonides megara basins to the east

fractal characteristics of nano pores in the lower silurian longmaxi shales from the upper yangtze platform south china abstract to better understand the fractal characteristics of nano pore structure and their effects on methane adsorption in marine shales we have conducted ultra low pressure nitrogen adsorption methane adsorption x ray diffraction xrd total organic carbon toc and vitrinite reflectance for eleven shale samples of the lower silurian longmaxi formation from the upper yangtze platform south china two fractal dimensions d 1 and d 2 at relative pressures of 0 0 5 and 0 5 1 respectively were obtained using the fractal frenkel halsey hill fhh method based on low pressure nitrogen adsorption isotherms the relationships among composition of the longmaxi shale toc clay minerals brittle minerals the pore structure parameters i e average pore diameter surface area pore volume and the fractal dimensions were investigated the results show that the longmaxi shale possesses fractal geometries with fractal dimension d 1 values ranging from 2 3542 to 2 4715 and fractal dimension d 2 values ranging from 2 5818 to 2 7497 the good positive correlation between fractal dimensions d 1 and the bet surface area and the strongly negative relationship between fractal dimensions d 2 and the average pore diameter indicate that d 1 can adequately characterize pore surface fractal dimension while d 2 represents the pore structure fractal dimension organic matter has a positive influence on the bet surface area and the bjh pore volume and a negative effect on the average pore diameter the bjh pore volume and the average pore diameter have a positive relationship trend with the clay minerals content whereas a negative linear trend with the brittle minerals content the mineralogical compositions and toc of the longmaxi shale have different impacts on the pore structures which in turn exert different effects on the fractal dimensions d 1 and d 2 both the fractal dimensions d 1 and d 2 have positive effects on the langmuir volume of methane adsorption however the fractal dimensions d 1 and d 2 have opposite influence on the langmuir pressures of methane adsorption thus the fractal dimensions can well be used to evaluate gas shale reservoir and shale gas accumulation in south china

an improved model for estimating the toc in shale formations abstract determination of the total organic carbon toc from well logs is an important step in formation evaluation of shale reservoirs the logr model is one of the most commonly used methods in determining the toc of the source rocks wang et al 2016 made three revisions on logr model to enhance the prediction accuracy one of which is to use a changeable slope of log 10 r t versus porosity logs to replace a fixed value based on the original logr model and wang s revision we propose an improved model for a better toc estimation in this paper specifically the approximate linear baseline is replaced by a theoretical one under this condition both the slope and resistivity and porosity log values of the baselined rocks vary from depth to depth the determination of theoretical baseline is presented and the varied baseline log values are obtained by a simple mathematical technique in addition to the shale play of western canada sedimentary basin two study areas of sichuan basin and ordos basin in china were used to assess the applications of the proposed model and its improvement over the original model the analysis and discussions presented in this paper indicate that the improved model offers more reliable results in shale plays with large lithological variations also the toc content of the three study areas was estimated using the proposed model the results showed that the toc values estimated from well logs and core analysis are in good agreement

a preliminary study on the pore characterization of lower silurian black shales in the chuandong thrust fold belt southwestern china using low pressure n2 adsorption and fe sem methods although lower silurian black shales within and around the sichuan basin have received renewed attention during the past few years because of their potential prospectivity for shale gas studies associated with shale gas reservoir evaluation are still rare in this study eight black shale core samples were collected from a well drilled recently in the chuandong thrust fold belt southwestern china and their geochemistry and pore structures were investigated using low pressure n2 adsorption analysis and field emission scanning electron microscopy fe sem observations the results show that the black shales have total organic carbon toc values ranging from 1 01 to 3 98 and their equivalent vitrinite reflectance values are in the range of 2 84 3 05 both mineral matrix and organic matter pores are well developed with pore sizes ranging from several to several hundred nanometers the total porosity for the eight samples ranges from 2 60 to 4 74 and the percentages of organic matter pores are estimated to be in the range of 31 62 the total surface area ranges from 5 06 m2 g to 19 32 m2 g and the micropore 2 nm surface area estimated by the t plot method ranges from 3 13 m2 g to 9 27 m2 g the toc values have positive relationships with the total porosity total surface area and the micropore 2 nm volume and surface area indicating toc may be an effective parameter for shale gas reservoir evaluation in the studied area

investigation on the pore structure and multifractal characteristics of tight oil reservoirs using nmr measurements permian lucaogou formation in jimusaer sag junggar basin abstract pore structure is a critical parameter to estimate the reservoir quality and evaluate the resource potential however the pore structure and heterogeneity of the unconventional tight oil reservoirs of permian lucaogou formation of jimusaer sag junggar basin are not studied well in this paper the multifractal analysis based on the nmr t 2 distributions was applied to investigate the pore structure and heterogeneity the reservoir quality index rqi and flow zone indicator fzi were calculated using porosity and permeability two parameters t 35 and t 50 were newly defined as relaxation times corresponding to the 35 and 50 saturation on the t 2 reverse accumulative curve respectively the results showed that the rqi and fzi values were extremely low and that the nmr t 2 distributions of water saturated samples had much short relaxation components with no or little long relaxation components indicating a complex and poor microscopic pore structure of tight oil rocks the typical multifractal characteristics such as the large values of singularity strength range revealed that the pore structures of samples were strongly heterogeneous it was also found that the clay contents have an obvious influence on the multifractal parameters and the fzi and new defined t 35 are two good indicators for heterogeneity of pore structure in addition the feasibility and applicability of calculating the multifractal parameters from nmr and other well logs were discussed

active faulting on the island of crete greece in order to characterize and quantify the middle late quaternary and ongoing deformation within the southern aegean forearc we analyse the major tectonic structures affecting the island of crete and its offshore the normal faults typically consist of 4 30 km long dipslip segments locally organised in more complex fault zones they separate carbonate and or metamorphic massifs in the footwall block from loose to poorly consolidated alluvial and colluvial materials within the hangingwall all these faults show clear evidences of recent re activations and trend parallel to two principal directions wnw ese and nne ssw based on all available data for both onland and offshore structures morphological and structural mapping satellite imagery and airphotographs remote sensing as well as the analysis of seismic profiles and the investigation of marine terraces and holocene raised notches along the island coasts for each fault we estimate and constrain some of the principal seismotectonic parameters and particularly the fault kinematics the cumulative amount of slip and the slip rate following simple assumptions and empirical relationships maximum expected magnitudes and mean recurrence periods are also suggested summing up the contribution to crustal extension provided by the two major fault sets we calculate both arc normal and arcparallel long term strain rates the occurrence of slightly deeper and more external low angle thrust planes associated with the incipient continental collision occurring in western crete is also analysed although these contractional structures can generate stronger seismic events m 7 5 they are probably much rarer and thus providing a minor contribution to the overall morphotectonic evolution of the island and the forearc a comparison of our geologicallybased results with those obtained from gps measurements show a good agreement therefore suggesting that the present day crustal deformation is probably active since middle quaternary and mainly related to the seismic activity of upper crustal normal faults characterized by frequent shallow 20 km moderate to strong seismic events seldom alternating with stronger earthquakes occurring along blind low angle thrust planes probably ramping from a deeper aseismic detachment ca 25 km this apparently contradicting co existence of juxtaposed upper tensional and lower compressional tectonic regimes is in agreement with the geodynamics of the region characterised by continental collision with nubia and the aegean mantle wedging

episodic uplift deduced from holocene shorelines in the perachora peninsula corinth area greece four raised shorelines between 1 1 m and 3 5 m have been identified at two localities on the perachora peninsula and were dated by ams 14c to between 6400 and 1500 calibrated years ago uplift movements seem to have occurred in increments of 0 8 0 3 m with a return period of about 1600 years the last uplift coincided with a regional tectonic paroxysm which has already been documented in several areas of the eastern mediterranean the average uplift rate was probably faster during the holocene than the average since the last interglacial period no important vertical displacement occurred in this area at the time of or after the 1981 earthquake but a new episode of coseismic uplift may be in preparation

permeability prediction from micp and nmr data using an electrokinetic approach theaccuratemodelingofoil gas andwaterreservoirsdependsfundamentallyuponaccesstoreliablerockpermeabilitiesthatcannotbeobtaineddirectlyfromdownholelogs instead a range of empirical models are usually employed we propose a new model that has been derived analytically from electrokinetic theory and is equally valid for all lithologies the predictions of the new model and four other common models kozeny carman berg swanson and van baaren have been compared using measurements carried out on fusedandunfusedglassbeadpacksaswellason91rocksamples representing 11 lithologies and three coring directions the new model provides the best predictions for the glass beadpacksaswellforallthelithologies thecruxofthenew modelistohaveagoodknowledgeoftherelevantmeangrain diameter forexample frommicpdata hence wehavealso predictedthepermeabilitiesof21northseawellcoresusing all five models and five different measures of relevant grain size these data show that the best predictions are provided by the use of the new model with the geometric mean grain size wehavealsoappliedthenewmodeltothepredictionof permeability from nmr data of a 500 m thick sand shale succession in the north sea by inverting the t2 spectrum to provide a value for the geometric mean grain size the new model shows a good match to all 348 core measurements fromthesuccession performingbetterthanthesdr timurcoates hscm andkozeny carmanpredictions