from a deformed peri tethyan carbonate platform to a fold and thrust belt an example from the central apennines italy abstract in the central apennines of italy the relationships between the foreland deformation of a peri tethyan carbonate platform lazio abruzzi domain and the subsequent contractional pattern have been clearly documented by means of stratigraphic and structural evidence stratigraphic and structural data point out the occurrence of pre thrusting normal fault systems and allow us to define their relationships with contractional structures miocene normal faults are particularly well documented by thickness and facies variation of foredeep deposits and by structural evidence these faults controlled sedimentation during tortonian early messinian times foredeep stage and produced most of the accommodation space for clastic deposits in their hanging walls on the contrary the subsequent positive inversion appears to be quite limited and generally the hanging wall sequences are not uplifted above the regional clear evidence that normal faults formed first and were later cut and or rotated during thrusting is supported by analyses carried out along the main fault surfaces the restoration of a balanced geological section across the study area based on the inference of an extended foreland affected by later contraction provided a total small shortening value this is lower than the previous estimated by several authors for the same foreland fold and thrust belt

the permian triassic transition and the onset of mesozoic sedimentation at the northwestern peri tethyan domain scale palaeogeographic maps and geodynamic implications the main aim of this paper is to review middle permian through middle triassic continental successions in european secondly areas of middle late permian sedimentation the permian triassic boundary ptb and the onset of triassic sedimentation at the scale of the westernmost peri tethyan domain are defined in order to construct palaeogeographic maps of the area and to discuss the impact of tectonics climate and sediment supply on the preservation of continental sediment at the scale of the western european peri tethyan basins the upper permian is characterised by a general progradational pattern from playa lake or floodplain to fluvial environments in the northern variscan belt domain areas of sedimentation were either isolated or connected to the large basin which was occupied by the zechstein sea in the southern variscan belt during the late permian either isolated endoreic basins occurred with palaeocurrent directions indicating local sources or basins underwent erosion and or there was no deposition these basins were not connected with the tethys ocean which could be explained by a high border formed by corsica sardinia palaeorelief and even parts of the kabilia microplate the palaeoflora and sedimentary environments suggest warm and semi arid climatic conditions at the scale of the whole study area an unconformity more or less angular is observed almost everywhere between deposits of the upper permian and triassic except in the central part of the germanic basin the sedimentation gap is more developed in the southern area where in some basins upper permian sediment does not occur the large sedimentary supply erosion and or lack of deposition during the late permian as well as the variable palaeocurrent direction pattern between themiddle late permian and the early triassic indicate a period of relief rejuvenation during the late permian during the induan all the intra belt basins were under erosion and sediment was only preserved in the extra belt domains the northern and extreme southern domains in the northern domain the central part of the germanic basin sediment was preserved under the same climatic conditions as during the latest permian whereas in the extreme southern domain it was probably preserved in the tethys ocean implying a large amount of detrital components entering themarinewaters mesozoic sedimentation began in the early olenekian the ephemeral fluvial systems indicate arid climatic conditions during this period three distinct areas of sedimentation occur a northern and southern domain separated by an intra belt domain the latter accumulated sediments during the early middle permian and experienced erosion and or no deposition conditions between the middle late permian and the beginning of mesozoic sedimentation dated as anisian to hettangian at the top of the lower triassic another tectonically induced more or less angular unconformity is observed the hardegsen unconformity which is dated as intra spathian and is especially found in the north european basins this tectonic activity created new source areas and a new fluvial style with marine influences at the distal part of the systems during the anisian and ladinian continental sedimentation was characterised by a retrogradational trend in other words the fluvial system evolved into fluvio marine environments attesting to a direct influence of the tethys ocean in the southern and northern domains both at the end of the olenekian spathian and during the anisian the presence of palaeosols micro andmacrofloras indicate less arid conditions throughout this domain

aeolian sand sea development along the mid cretaceous western tethyan margin spain erg sedimentology and palaeoclimate implications the existence of a mid cretaceous erg system along the western tethyan margin iberian basin spain was recently demonstrated based on the occurrence of wind blown desert sands in coeval shallow marine deposits here the first direct evidence of this mid cretaceous erg in europe is presented and the palaeoclimate and palaeoceanographic implications are discussed the aeolian sand sea extended over an area of 4600 km2 compound crescentic dunes linear draa and complex aeolian dunes sand sheets wet dry and evaporitic interdunes sabkha deposits and coeval extradune lagoonal deposits form the main architectural elements of this desert system that was located in a sub tropical arid belt along the western tethyan margin sub critically climbing translatent strata grain flow and grain fall deposits pin stripe lamination lee side dune wind ripples soft sediment deformations vertebrate tracks biogenic traces tubes and wood fragments are some of the small scale structures and components observed in the aeolian dune sandstones at the boundary between the aeolian sand sea and the marine realm intertonguing of aeolian deposits and marine facies occurs massive sandstone units were laid down by mass flow events that reworked aeolian dune sands during flooding events the cyclic occurrence of soft sediment deformation is ascribed to intermittent marine flooding of aeolian dunes and associated rise in the water table the aeolian erg system developed in an active extensional tectonic setting that favoured its preservation because of the close proximity of the marine realm the water table was high and contributed to the preservation of the aeolian facies a sand drift surface marks the onset of aeolian dune construction and accumulation whereby aeolian deposits cover an earlier succession of coastal coal deposits formed in a more humid period a prominent aeolian super surface forms an angular unconformity that divides the aeolian succession into two erg sequences this super surface formed in response to a major tectonic reactivation in the basin and also marks the change in style of aeolian sedimentation from compound climbing crescentic dunes to aeolian draas the location of the mid cretaceous palaeoerg fits well to both the global distribution of other known cretaceous erg systems and with current palaeoclimate data that suggest a global cooling period and a sea level lowstand during early mid cretaceous times the occurrence of a sub tropical coastal erg in the mid cretaceous of spain correlates with the exposure of carbonate platforms on the arabian platform during much of the late aptian to middle albian and is related to this eustatic sea level lowstand

high precision analysis of an embryonic extensional fault related fold using 3d orthorectified virtual outcrops the viewpoint importance in structural geology abstract image based 3d modeling has recently opened the way to the use of virtual outcrop models in geology an intriguing application of this method involves the production of orthorectified images of outcrops using almost any user defined point of view so that photorealistic cross sections suitable for numerous geological purposes and measurements can be easily generated these purposes include the accurate quantitative analysis of fault fold relationships starting from imperfectly oriented and partly inaccessible real outcrops we applied the method of image based 3d modeling and orthorectification to a case study from the northern apennines italy where an incipient extensional fault affecting well layered limestones is exposed on a 10 m high barely accessible cliff through a few simple steps we constructed a high quality image based 3d model of the outcrop in the model we made a series of measurements including fault and bedding attitudes which allowed us to derive the bedding fault intersection direction we then used this direction as viewpoint to obtain a distortion free photorealistic cross section on which we measured bed dips and thicknesses as well as fault stratigraphic separations these measurements allowed us to identify a slight difference i e only 0 5 between the hangingwall and footwall cutoff angles we show that the hangingwall strain required to compensate the upward decreasing displacement of the fault was accommodated by this 0 5 rotation i e folding and coeval 0 8 thickening of strata in the hangingwall relatively to footwall strata this evidence is consistent with trishear fault propagation folding our results emphasize the viewpoint importance in structural geology and therefore the potential of using orthorectified virtual outcrops

stratigraphy and facies architecture of the fluvial aeolian lacustrine sergi formation upper jurassic reconcavo basin brazil abstract the sergi formation encompasses an upper jurassic fluvial eolian lacustrine succession deposited within a wide intracratonic basin its sand bodies represent the largest and more important reservoirs in the reconcavo basin hosting 362 million m 3 of oil in place the main goal of this paper is to provide a detailed stratigraphic analysis of the sergi formation based on core and outcrop data it was achieved through the recognition and correlation of regional surfaces that have allowed the subdivision of this unit into distinct depositional sequences and the reconstruction of its depositional history the studied succession can be subdivided into three unconformity bounded sequences sequence i is composed of lacustrine mudstone at its base which is overlain by fine to medium grained sandstone related to aeolian dune and sand sheet and ephemeral fluvial stream deposits fluvial strata indicate northeastward flowing streams whereas aeolian dune deposits suggest the action of southwestward blowing winds the regional unconformity bounding sequences i and ii denotes both a climate change and tectonic rearrangement of the basin this surface delineates a change in the depositional style from fluvial aeolian lacustrine sequence i to entirely fluvial sequence ii the latter includes coarse grained to conglomeratic sandstone deposited within northwestward flowing braided channel belts changes in fluvial palaeocurrent from sequence i to ii indicate rearrangement of the drainage system related to basin tectonism furthermore a change in the fluvial discharge regime took place as a result of a change from a drier to a wetter climate fluvial deposition in sequence i was related to ephemeral streams whereas fluvial facies architecture of the sequence ii deposits indicates perennial braided streams with significant discharge variation another regional unconformity this time related to a stratigraphic base level fall and consequent widespread basinwide aeolian deflation separates the braided fluvial facies of sequence ii from the fine to medium grained sandstones ascribed to sheet floods aeolian dunes and aeolian sand sheets of sequence iii the resumption of aeolian sedimentation indicates a return to drier conditions in the basin the abrupt change from fluvial aeolian deposits to the lacustrine deposits of the overlying itaparica formation suggest a rapid rise of the water table and consequent basinwide flooding

sequential architecture and cyclicity in permian desert deposits brodick beds arran scotland this study of ancient desert deposits permian brodick beds tests the possibility that cyclicityin these interbedded aeolian fluvial and lacustrine deposits was orbitally controlled the 740 m thicksuccession of desert deposits forms one sequence which can be divided into three genetic units a majordeflation surface forms the basal sequence boundary and represents a drop in base level groundwatertable on top of the sequence boundary are rather uniform aeolian dune and sand sheet sediments unit1 formed in an erg during low base level with increasing rates of base level rise they are followed byinterbedded aeolian dune aeolian sand sheet and flood reworked aeolian sediments unit 2 representingerg margin deposits formed during increasing rates of base level rise the uppermost part of the sequenceis composed of gravel sheets unit 3 representing alluvial fan deposition during a high base level withdecreasing rates of base level rise the succession is cyclic and spectral analysis of sedimentary andgeochemical parameters reveal cycles with a thickness of 25 7 29 3 m 34 5 m and 64 5 m and fieldworkreveals cycles of 155 m and 675 m these sedimentary cycles are thought to reflect climatic oscillations the lack of detailed time control makes it diffcult to link these climatic fluctuations to orbital cycles although the detected cyclicity matches well with milankovitch theory

evaluating roughness scaling properties of natural active fault surfaces by means of multi view photogrammetry abstract fault roughness is a measure of the dimensions and distribution of fault asperities which can act as stress concentrators affecting fault frictional behaviour and the dynamics of rupture propagation studies aimed at describing fault roughness require the acquisition of extremely detailed and accurate datasets of fault surface topography fault surface data have been acquired by methods such as lidar laser profilometers and white light interferometers each covering different length scales and with only lidar available in the field here we explore the potential use of multi view photogrammetric methods in fault roughness studies which are presently underexplored and offer the advantage of detailed data acquisition directly in the field we applied the photogrammetric method to reproduce fault topography by using seven dm sized fault rock samples photographed in the lab three fault surfaces photographed in the field and one control object used to estimate the model error we studied these topographies estimating their roughness scaling coefficients through a fourier power spectrum method our results show scaling coefficients of 0 84 0 17 along the slip direction and 0 91 0 17 perpendicularly to it and are thus comparable to those results obtained by previous authors this provides encouragement for the use of photogrammetric methods for future studies particularly those involving field based acquisition where other techniques have limitations

roughness of fault surfaces over nine decades of length scales 1 we report on the topographic roughness measurements of five exhumed faults and thirteen surface earthquake ruptures over a large range of scales from 50 m to 50 km we used three scanner devices lidar laser profilometer white light interferometer spanning complementary scale ranges from 50 m to 10 m to measure the 3 d topography of the same objects i e five exhumed slip surfaces vuache sillingy bolu corona heights dixie valley magnola a consistent geometrical property i e self affinity emerges as the morphology of the slip surfaces shows at first order a linear behavior on a log log plot where axes are fault roughness and spatial length scale covering five decades of length scales the observed fault roughness is scale dependent with an anisotropic self affine behavior described by four parameters two power law exponents h constant among all the faults studied but slightly anisotropic h 0 58 0 07 in the slip direction and h 0 81 0 04 perpendicular to it and two pre factors showing variability over the faults studied for larger scales between 200 m and 50 km we have analyzed the 2 d roughness of the surface rupture of thirteen major continental earthquakes these ruptures show geometrical properties consistent with the slip perpendicular behavior of the smaller scale measurements our analysis suggests that the inherent non alignment between the exposed traces and the along or normal slip direction results in sampling the slip perpendicular geometry although a data gap exists between the scanned fault scarps and rupture traces the measurements are consistent within the error bars with a single geometrical description i e consistent dimensionality over nine decades of length scales

fault roughness at seismogenic depths from lidar and photogrammetric analysis fault surface roughness is a principal factor influencing earthquake mechanics and particularly rupture initiation propagation and arrest however little data currently exist on fault surfaces at seismogenic depths here we investigate the roughness of slip surfaces from the seismogenic strike slip gole larghe fault zone exhumed from ca 10 km depth the fault zone exploited pre existing joints and is hosted in granitoid rocks of the adamello batholith italian alps individual seismogenic slip surfaces generally show a first phase of cataclasite production and a second phase with beautifully preserved pseudotachylytes of variable thickness we determined the geometry of fault traces over almost five orders of magnitude using terrestrial laser scanning lidar ca 500 to 1 10 m is not anisotropic and less evolved than at smaller scales these observations are consistent with an evolution of roughness due to fault surface processes that takes place only at scales smaller or comparable to the observed net slip differences in roughness evolution between shallow and deeper faults the latter showing evidences of seismic activity are interpreted as the result of different weakening versus induration processes which also result in localization versus delocalization of deformation in the fault zone from a methodological point of view the technique used here is advantageous over direct measurements of exposed fault surfaces in that it preserves in cross section all of the structures which contribute to fault roughness and removes any subjectivity introduced by the need to distinguish roughness of original slip surfaces from roughness induced by secondary weathering processes moreover offsets can be measured by means of suitable markers and fault rocks are preserved hence their thickness composition and structural features can be characterised providing an integrated dataset which sheds new light on mechanisms of roughness evolution with slip and concomitant fault rock production

evolution of the lower saxony basin abstract the lower saxony basin is a 300 km long and 65 km wide late jurassic and early cretaceous trough which parallels the northern margin of the rhenish massif this basin became inverted during the senonian and paleocene the lower saxony basin is the most important oil province of germany past production amounts to 200 10 6 t of oil 1 5 10 9 bbl the lower saxony basin is superimposed on the late carboniferous variscan foredeep basin and the frontal structures of the variscan fold belt during the permian to middle jurassic the area formed part of the northwest european basin differential subsidence of the lower saxony basin was initiated during the late jurassic and persisted till albian time this involved reactivation of permo carboniferous fracture systems by divergent wrenching a major aptian deep seated laccolith is evident in the western part of the lower saxony basin during the senonian and paleocene sinistral convergent wrenching induced uplift of the basin floor and folding of its sedimentary fill the margins of the inverted lower saxony basin are thrust over the adjacent stable platform areas the differential subsidence of the lower saxony basin can be related to a period of major crustal extension in the north sea rift basin inversion coincides with important orogenic events in the alpine system and is thought to have been induced by intra plate compressional stresses

structural anisotropy of normal fault surfaces abstract precise description of natural fault surfaces is indispensable to understanding the geometry mechanics and fluid transport properties of faults profiles of fault surfaces in the wasatch fault zone and oquirrh mountains utah are measured at 30 increments within the fault plane to determine the directional anisotropy of surface roughness at wavelengths between 10 3 m and 30 m and then compared with profiles of larger scale fault surfaces surface anisotropy and an increasing ratio of surface amplitude to wavelength are consistent with self affine fault topography at wavelengths between 1 mm and approximately 5 km fractal dimension of surface profiles generally decreases systematically as the angle to the slip direction increases directional anisotropy is described by an azimuthal scaling function k sin 0 or af af max 1 sin 1 where and af are the amplitude to wavelength ratio and anisotropy factor respectively at azimuth measured clockwise relative to slip direction within the fault surface and 0 is the amplitude to wavelength ratio parallel to slip direction k 90 0 is an anisotropy coefficient and increases systematically with spatial wavelength on the fault surface characterization of natural fault surfaces provides parameters such as fractal dimension d intercept log c of power spectra profile variance and variation in anisotropy factor af which are needed to generate fractal models of natural fault surfaces using spectral synthesis we generate sample models which illustrate the differences between fault surfaces characterized by constant versus azimuthally varying fractal dimension the latter model surfaces contain low amplitude corrugations superimposed on elongate ridges which parallel slip direction this surface texture resembles that of natural fault surfaces that refract across lithologic layering or are cut by secondary faults such as r and r shears

evolution of slip surface roughness through shear a significant part of displacement in fault zones occurs along discrete shear surfaces the evolution of fault surface topography is studied here in direct shear laboratory experiments matching tensile fracture surfaces were sheared under imposed constant normal stress and sliding velocity the roughness evolution was analyzed using measurements of surface topography before and after slip we show that shearing reduces the initial surface roughness at all measurement scales at all wavelengths the roughness ratio between initial and final roughness increases as a function of the slip distance for a given test the roughness ratio increases with wavelength up to a few millimeters beyond which the ratio becomes wavelength independent at this region the roughness measured after slip follows a power law similar to that of the initial tensile fracture surface we interpret this geometrical evolution as a consequence of the deformation stage of interlocked asperities which is followed by shear induced dilation

roughness of natural fault surfaces the roughness of fault surfaces is important in the mechanics of fault slip and could play a role in determining whether sliding occurs via earthquakes or fault creep we have made preliminary measurements of the power spectral density of several fault surfaces over the wavelength range from 10 5 to 1 m using field and laboratory scale profilimeters the fault surfaces are strongly anisotropic profiles parallel to the slip direction have amplitudes about one order of magnitude lower than those perpendicular to the slip direction over most of the wavelength interval measured fault roughness perpendicular to the slip direction is similar to the roughness of natural joints the greater smoothness in the slip direction presumably represents wear resulting from slip combining our data with previous measurements of the roughness spectrum of the san andreas fault shows that fault surfaces are fractal over nearly eleven orders of magnitude in wavelength

sedimentary architecture of an ancient linear megadune barremian neuquen basin insights into the long term development and evolution of aeolian linear bedforms linear aeolian bedforms are the most abundant bedform type in modern earth sand seas and are very common in our solar system despite their abundance the long term development of these bedforms and its impact upon the resulting sedimentary architecture in the geological record is still poorly understood the aims of this paper are to study the exposed record of an ancient linear megadune in order to discuss the factors that impact the development and sedimentary architecture of aeolian linear bedforms the outcrops of the ancient troncoso sand sea barremian neuquen basin argentina provide a unique opportunity to access a preserved megadune record with an external body geometry that unequivocally confirms its linear morphology architectural analysis of the bedform record reveals significant differences for several aspects of cross stratified set bodies and bounding surfaces and allows for the identification of three architectural complexes insights from deterministic models analysis of set body relative chronology and distribution suggest that complexes result from distinctive phases in bedform development it also clearly shows that the megadune s construction was achieved by expansion from a core where the oldest deposits are located and that its development was characterized by sustained growth and strong longitudinal dynamics factors that impact the development and architecture of linear bedforms are identified discussed and compared to bedforms of transverse dynamics finally a scheme of expected styles of sedimentary architecture for linear bedforms is presented this case study shows how growth can be a critical factor conditioning linear bedform architecture and indicates how the preservation of certain styles of sedimentary architecture in the geological record may not be as unusual as previously thought

intensifying aeolian activity following the end permian mass extinction evidence from the late permian early triassic terrestrial sedimentary record of the ordos basin north china

controls on marine erg margin cycle variability aeolian marine interaction in the mid cretaceous iberian desert system spain the interaction between aeolian dunes of the iberian erg and tethys waters during the mid cretaceous led to a variety of sedimentary facies associations such as subtidal deposits aeolian dunes playa lakes coastal lakes with tidal creeks and marshes and lagoonal embayments with tide influenced delta deposits facies associations are organized in several stacked cycles every cycle is defined by a sand drift surface separating playa lake deposits below from aeolian dune deposits above followed by a transgressive surface separating aeolian deposits below from shallow marine deposits above the latter are covered by playa lake deposits and finally topped by the next sand drift surface similar marine erg margin cycles have been explained previously in terms of high order relative sea level variations normally controlled by glacioeustasy the studied erg margin developed during the mid cretaceous which is considered to be the archetypal example of a polar ice free greenhouse period this manuscript presents an alternative explanation for the cycles as caused by climate induced variations in the aeolian sediment supply in this scenario orbitally induced latitudinal shifts of the boundary between climate belts led to alternating periods of increased and decreased precipitation in the highland catchments of the back erg system variscan iberian massif when climate belts shifted to lower latitudes back erg highlands were under the influence of the northern warm humid belt while arid conditions prevailed in the lowland central erg increased precipitation in the highlands and the consequent recharge of ground water led to a rise of the phreatic level in the erg system that diminished wind erosion and windblown sediment input to the fore erg so that the desert margin contracted with ongoing basin subsidence this favoured the transgression the increased desert ground water flux favoured permanent coastal lakes in the fore erg margin and the local development of vegetation in places where such lakes lagoons were connected to the sea tidal channels were active as seen nowadays along the desert coast of qatar persian gulf when climate belts moved to higher latitudes the catchment areas in the back erg iberian massif were under the influence of the northern hot arid belt and a decrease of precipitation led to a drop of the phreatic level allowing deflation of dunes and exposed wadi channel floors and the formation of desert pavements and deflation lags in the back erg area this favoured the import of large volumes of windblown sand and dust forcing progradation of the erg and consequently a retreat of the coastline the sand fraction accumulated in climbing aeolian dunes and dust was trapped in extensive playa lake systems another long term allocyclic control is formed by active extensional tectonics that enhanced the creation of accommodation space especially in the first cycle a high ground water table sustained by subsurface water supply from the variscan iberian massif generated coastal fresh brackish lakes in which tide influenced meandering channels and salt marshes developed erg margin cycles thin upward in response to a decrease of the rate of basin subsidence suggesting that transgressions led to deep erosion of the underlying aeolian dune sands

ground based and uav based photogrammetry a multi scale high resolution mapping tool for structural geology and paleoseismology this contribution reviews the use of modern 3d photo based surface reconstruction techniques for high fidelity surveys of trenches rock exposures and hand specimens to highlight their potential for paleoseismology and structural geology we outline the general approach to data acquisition and processing using ground based photographs acquired from standard dslr cameras and illustrate the use of similar processing approaches on imagery from unmanned aerial vehicles uavs it is shown that digital map and trench data can be acquired at ultra high resolution and in much shorter time intervals than would be normally achievable through conventional grid mapping the resulting point clouds and textured models are inherently multidimensional x y z point orientation colour texture archival and easily transformed into orthorectified photomosaics or digital elevation models dems we provide some examples for the use of such techniques in structural geology and paleoseismology while pointing the interested reader to free and commercial software packages for data processing visualization and 3d interpretation photogrammetric models serve to act as an ideal electronic repository for critical outcrops and observations similar to the electronic lab book approach employed in the biosciences this paper also highlights future possibilities for rapid semi automatic to automatic interpretation of the data and advances in technology

complex sedimentology and palaeohabitats of holocene coastal deserts their topographic controls and analogues for the mid cretaceous of northern iberia abstract desert coasts in plate margins contain one of the most variable sedimentary records in terms of facies and stacking patterns reliefs in these basins together with massif palaeogeography and palaeotopography strongly control the spatial distribution of facies belts and complex lateral facies changes between very different coeval sub environments leading to mixtures of sedimentary particles with variable composition palaeotopography and palaeogeography also control the distribution of flora palaeohabitats in the desert basins depending on the spatial distribution of fresh water the basin geometry the topographic variability and associated phreatic level as well as the effective distance from highlands to the coast the albian desert basin that developed in northern iberia presents similarities with the geomorphology of modern oman uae and eritrea desert coasts in both systems cretaceous and holocene the distance between highlands and arid coastline determines the occurrence of extensive aeolian sand seas e g wide desert basin where distance between the highlands and the coastline increases or the development of wadi fed alluvial fans that reach directly the desert coast e g narrow desert basin leading to a variety of clastic and mixed carbonate facies due to prevailing arid conditions vegetation is mainly restricted to highlands and water conditioned lowland environments such as wadis tidal coastal marshes and lagoons depending on sea influence and water availability cretaceous vegetation in iberia were characterized by montane communities including arboreal shrubby gymnosperms mainly conifers and lowland communities composed by a patchy mixture of ferns cupressaceae cypress family cheirolepidiaceae and early angiosperms and or costal woodlands incorporating araucariaceae monkey puzzle tree family this distribution presents similarities with the ecosystems observed today in eritrea mountains and other holocene desert coasts

constant dimensionality of fault roughness from the scale of micro fractures to the scale of continents 1 many faults and fractures in various natural and man made materials share a remarkable common fractal property in their morphology we report on the roughness of faults in rocks by analyzing the out of plane fluctuations of slip surfaces they display a statistical power law relationship with a nearly constant fractal exponent from millimeter scale micro fractures in fault zones to coastlines measuring thousands of kilometers that have recorded continental breakup a possible origin of this striking fractal relationship over 11 orders of magnitude of length scales is that all faulting processes in rocks share common characteristics that play a crucial role in the shaping of fault surfaces such as the effects of elastic long range stress interactions and stress screening by mechanical heterogeneities during quasi static fracture growth

relation between continental strike slip earthquake segmentation and thickness of the crust 1 high resolution maps of large continental strike slip earthquake surface ruptures show that they are formed of fault segments these segments are bounded by fault bends step overs or combinations of the two the lowest limit in size for such segments may not be relevant in the understanding of earthquake mechanics as it pertains to the granular properties of fault zones the maximum limit in segment length however is important as it is directly relates to the maximum extent of seismic rupture to measure the length of the segments a new quantitative method based on piecewise linear fitting is developed and is used to automatically retrieve segments from earthquake rupture maps next this approach is tested against a set of ten continental strike slip earthquake ruptures derived from similar high quality maps the test suggests that segments have a maximum length of 18 km independent of regional tectonic setting slip inversions for earthquakes based on seismological and or geodetic data most often are not unique and can show some variability even for one particular event some basic characteristics however such as total moment release or general source geometry seem to persist that are relevant to earthquake mechanics measurements of the maximum horizontal extent of individual slip patches derived from seismic source inversion for strike slip ruptures show that their strike dimension does not increase infinitely with magnitude but instead reaches a maximum value of 25 km these two independent lines of observations complemented by earlier data and analog experiments suggest that it is the thickness of the seismogenic crust that controls the structural scaling of the length of seismic segments and that it is independent of the ultimate size of individual earthquakes

mapping folds and fractures in basement and cover rocks using uav photogrammetry cape liptrap and cape paterson victoria australia abstract brittle and ductile deformation of alternating layers of devonian sandstone and mudstone at cape liptrap victoria australia resulted in upright folds with associated fold accommodation faults and multiple fracture sets structures were mapped at the fold stack locality at cape liptrap using high resolution aerial photographs acquired by a digital camera mounted on an unmanned aerial vehicle uav subsequent photogrammetric modelling resulted in georeferenced spatial datasets point cloud digital elevation model and orthophotograph with sub cm resolution and cm accuracy which were used to extract brittle and ductile structure orientation data an extensive dataset of bedding measurements derived from the dense point cloud was used to compute a 3d implicit structural trend model to visualise along strike changes of devonian tabberabberan folds at the fold stack locality and to estimate bulk shortening strain this model and newly collected data indicate that first generation shallowly south southwest plunging upright folds were gently refolded about a steeply plunging subvertical fold axis during a devonian low strain north south shortening event this also led to the local tightening of first generation folds and possibly strike slip movement along regional scale faults in order to distinguish fractures associated with devonian compression from those that formed during cretaceous extension and later inversion we compared the five fracture sets defined at cape liptrap to previously mapped joints and faults within the overlying sedimentary cover rocks of the cretaceous strzelecki group gippsland basin which crop out nearby an east southeast trending fracture set that is not evident in the strzelecki group can be linked to the formation of devonian folds additionally hinge line traces extracted from the fold stack dataset are aligned parallel to a dominant fracture set within the overlying cover sediments this suggests that basement structures folds and coeval parallel faults have an important influence on fault and joint orientations within cretaceous cover rocks

braided rivers within an arid alluvial plain example from the lower triassic western german basin recognition criteria and expression of stratigraphic cycles based on a detailed sedimentological analysis of lower triassic continental deposits in the western germanic sag basin i e the eastern part of the present day paris basin the conglomerat basal gres vosgien and conglomerat principal formations three main depositional environments were identified i braided rivers in an arid alluvial plain with some preserved aeolian dunes and very few floodplain deposits ii marginal erg i e braided rivers aeolian dunes and aeolian sand sheets and iii playa lake an ephemeral lake environment with fluvial and aeolian sediments most of the time aeolian deposits in arid environments that are dominated by fluvial systems are poorly preserved and particular attention should be paid to any sedimentological marker of aridity such as wind worn pebbles ventifacts sand drift surfaces and aeolian sand sheets in such arid continental environments stratigraphic surfaces of allocyclic origin correspond to bounding surfaces of regional extension elementary stratigraphic cycles i e the genetic units have been identified for the three main continental environments the fluvial type fluvial aeolian type and fluvial playa lake type at the time scale of tens to hundreds of thousands of years these high frequency cycles of climatic origin are controlled either by the groundwater level in the basin or by the fluvial siliciclastic sediment input supplied from the highland lower triassic deposits from the germanic basin are preserved mostly in endoreic basins the central part of the basin is arid but the rivers are supplied with water by precipitation falling on the remnants of the hercynian variscan appalachian mountains consequently a detailed study of alluvial plain facies provides indications of local climatic conditions in the place of deposition whereas fluvial systems only reflect climatic conditions of the upstream erosional catchments

preservation of pre vegetational mixed fluvio aeolian deposits in a humid climatic setting an example from the middle proterozoic eriksfjord formation southwest greenland abstract sedimentological studies of a 30 m thick coastal cliff section within the middle proterozoic eriksfjord formation in western south greenland reveals three distinct types of fluvial sand sheet deposits that reflect perennial streams type i semi perennial streams type ii and ephemeral flash floods type iii perennial river sand sheets are characterised by co sets of medium scale trough cross beds interbedded with isolated medium and large scale high angle tabular cross beds indications of desiccation or subaerial exposure are absent semi perennial fluvial sand sheets consist predominantly of low angle cross beds interbedded with isolated sets of high angle tabular cross beds with common reactivation surfaces horizontal lamination and climbing ripple lamination form subordinate structures associated with the sand sheets are adhesion structures and 0 05 0 4 m thick sets of wind ripple lamination indicating periods of subaerial exposure and aeolian reworking high energy ephemeral flash flood sand sheets consist almost exclusively of planar parallel lamination and climbing ripple lamination with some isolated sets of low angle cross bedding scouring and internal truncation surfaces are common the three types of sand sheets are considered to reflect deposition under changing climatic conditions varying from humid to arid or semi arid aeolian deposits are preserved within the sand sheets showing characteristics of dominantly perennial flow punctuated by shorter periods of desiccation type ii while sand sheets showing features typical of arid and or semi arid flow conditions type iii contain no preserved aeolian deposits this selective preservation is interpreted to be a result of the combined effect of groundwater table level and fluvial style which in turn are inferred to have been controlled by the climatic regime the deposits show that during pre vegetational times the preservation of aeolian deposits under certain conditions may be more optimal in fluvial systems formed in a humid climate than in fluvial systems formed under semi arid or arid circumstances the occurrence of aeolian deposits within a precambrian succession of fluvial deposits therefore need not be an indication of the most arid environmental conditions

aeolian sediments in lower to middle triassic rocks of central wyoming abstract the lower to middle triassic red peak and crow mountain formations of central wyoming have commonly been interpreted as being of shallow marine or shelf origin this paper presents conclusive evidence of an aeolian origin for parts of the two formations the interpretation is based on highly indicative sedimentary structures including wind ripple grainfall and grainflow strata lag deposits and granule ripples in the sediments of these formations facies in the upper red peak and lower crow mountain formations represent aeolian dune sandsheet wet interdune and sabkha environments emphasis is placed on the recognition and interpretation of correlative surfaces of regional extent which not only allow subdivision of the aeolian sediments into different genetic sequences but also aid in the reconstruction of the depositional history the recognition of an aeolian deposystem and of regional bounding surfaces adds valuable information to the efforts of reconstructing the triassic paleogeography of the western interior

evolution of hierarchical self similar geometry of experimental fault zones implications for seismic nucleation and earthquake size 1 the geometry of fault zones and its evolutionary trend were experimentally investigated for samples of calcareous siltstone nodule through a repetitive procedure of axial loading to grow faults a little close up photographing of faults that appeared on the side surface of the samples and axial loading again irrespective of their size fault zones are composed of three or four fault segments and compression type fault jogs smaller segment jog structures are nested in larger segments forming a hierarchical fault zone structure as a whole and they show self similarities fault zones grow keeping this self similar hierarchical structure on the basis of this fault zone geometry we successfully derived the gutenberg richter s law as well as the previously known relationship of seismic nucleation sizes to seismic moments these results suggest that fundamentally any seismic rupture nucleates at a smaller jog asperity of a lower hierarchical rank and terminates eventually at a larger jog barrier of a higher rank mimicking the hierarchical fault zone geometry

structural evolution timing and tectonic style of the sole pit inversion abstract the nw se oriented sole pit high located in the western half of the southern north sea basin is the result of three different structural processes initiated during the late palaeozoic basin subsidence probably related to late hercynian pull apart movements led to continuous sedimentation from the permian to the middle jurassic mid jurassic doming of its eastern flank followed by erosion transtensional movements and differential subsidence until the early cretaceous reflect the mid and late kimmerian crustal distension and fragmentation of the north sea rift basinwide inversion occurred between the turonian and the campanian and was repeated in the oligocene resulting in a total uplift of some 1500 m the present structural style is represented by a complex network of transpressional and transtensional faults at permian rotliegend levels which are thought to represent the upward termination of a series of wrench induced flower structures with a right lateral sense of displacement these faults are detached by zechstein and triassic salt from more orderly transtensional faults systems at shallower levels in areas where salt is absent late kimmerian normal faults became reactivated in a reverse sense during inversion however the relationship of these shallow mappable tectonic components to the deeper pre permian structure of the sole pit high and to the underlying crustal configuration remains speculative

upper permian zechstein supergroup carbonate evaporite platform palaeomorphology in the uk southern north sea abstract seismic interpretation geological mapping and depth conversion of the zechstein supergroup z2 cycle using high quality well calibrated three dimensional 3 d seismic has revealed the complex palaeomorphology of a deeply buried ancient carbonate shelf margin on the southwestern margin of the southern permian basin the new mapping shows that the margin comprises a series of corrugated embayments and promontories which extend up to 5 km 3 mi into the basin and locally have a palaeobathymetric relief of 200 m 650 ft well calibration across the margin demonstrates a strongly bipartite lateral thickness distribution between a high velocity anhydrite dominated shelf and a lower velocity halite dominated basin strong lateral and vertical velocity variations in the upper permian zechstein supergroup are known to have major impacts upon seismic imaging and depth conversion in the spb the resulting uncertainty remains one of the major challenges when interpreting and assessing the prospectivity of the underlying upper permian rotliegend group leman sandstone formation reservoirs in the uk southern north sea an understanding of the zechstein shelf edge s 3 d physiography and its velocity variation has implications for the delineation of traps containing the prospective reservoirs that lie below recognition of the complexity and effects of this shelf margin contributed to the recent juliet discovery whose position outside of the presently defined rotliegend group play fairway suggests that prospectivity is more extensive along the basin margin than previously thought as such the work provides a means by which to identify and delineate new structures and extend the life of this mature yet prolific gas province

high resolution 3d laser scanner measurements of a strike slip fault quantify its morphological anisotropy at all scales 1 the surface roughness of a recently exhumed strike slip fault plane has been measured by three independent 3d portable laser scanners digital elevation models of several fault surface areas from 1 m2 to 600 m2 have been measured at a resolution ranging from 5 mm to 80 mm out of plane height fluctuations are described by non gaussian distribution with exponential long range tails statistical scaling analyses show that the striated fault surface exhibits self affine scaling invariance with a small but significant directional morphological anisotropy that can be described by two scaling roughness exponents h1 0 7 in the direction of slip and h2 0 8 perpendicular to the direction of slip

euclidean and fractal models for the description of rock surface roughness accurate description of the topography of rock surfaces is essential because surface roughness affects frictional strength the flow of fluids in joints and fractures the seismic behavior of faults and the formation of gouge and breccia in fault zones real rock surfaces can be described using self similar and self affine fractal models of surface roughness if a surface is self similar a small portion of the surface when magnified isotropically will appear statistically identical to the entire surface if a surface is self affine a magnified portion of the surface will only appear statistically identical to the entire surface if different magnifications are used for the directions parallel and perpendicular to the surface at least two parameters are required to describe a fractal model one parameter typically describes how roughness changes with scale while the other specifies the variance or surface slope at a reference scale the divider method and the spectral method are in common use to determine the best fit fractal model from surface profile data power spectra from self similar surfaces have slopes of 3 on log log plots of power spectral density versus spatial frequency while spectra from self affine surfaces have slopes other than 3 power spectra can be interpreted with greater facility if dimensionless amplitude to wavelength ratios are contoured on plots of power spectral density versus frequency the topography of many natural rock surfaces including both fractures and faults is approximately self similar within the 6 5 order of magnitude wide wavelength band of 10 m to 40 m within smaller wavelength bands natural rock surfaces may exhibit self affine behavior

high resolution stratigraphic architecture and lithological heterogeneity within marginal aeolian reservoir analogues marginal aeolian successions contain different lithological units with variable geometries dimensions and spatial distributions such variations may result in considerable heterogeneity within hydrocarbon reservoirs developed in successions of this type which poses a high risk to their efficient development here such heterogeneity is described and characterized at inter well 1 km scales using two well exposed outcrop analogues of end member marginal aeolian deposits from the permian cedar mesa sandstone and jurassic page sandstone of south central utah usa the sedimentology and stratigraphic architecture of the cedar mesa sandstone was studied in a 1 2 km2 area in the indian creek region of southern utah where the interval consists of interbedded fluvial and aeolian deposits representative of a fluvial dominated erg margin the page sandstone was studied in a 4 3 km2 area near escalante close to the utah arizona border where it consists of interbedded sabkha and aeolian deposits representative of a transitional marine erg margin the three dimensional stratigraphic architectures of both reservoir analogues have been characterized in order to establish the dimensions geometries and connectivity of high permeability aeolian sandstones facies architecture of the aeolian sabkha deposits is characterized by laterally continuous aeolian sandstone layers of relatively uniform thickness that alternate with layers of heterolithic sabkha deposits aeolian sandstones are thus likely to form vertically unconnected but laterally widespread flow units in analogous reservoirs facies architecture in the aeolian fluvial deposits is more complex because it contains alternating intervals of aeolian sandstone and fluvial heterolithic strata both of which may be laterally discontinuous at the studied length scales aeolian sandstones encased by fluvial heterolithic strata may form small isolated flow units in analogous reservoirs although the limited continuity of fluvial heterolithic strata results in vertical connectivity between successive aeolian sandstones in other locations these architectural templates may be used to condition zonation schemes in models of marginal aeolian reservoirs

sedimentary cycles and facies architecture of aeolian fluvial strata of the upper jurassic guara formation southern brazil the upper jurassic guara formation comprises an 80 200 m thick continental succession exposed in the western portion of the rio grande do sul state brazil it comprises four distinct facies associations i simple to locally composite crescentic aeolian dune sets ii aeolian sand sheets iii distal floodflows and iv fluvial channels the vertical stacking of the facies associations defines several 5 14 m thick wetting upward cycles each cycle starts with aeolian dune sets followed by aeolian sand sheets deposits and culminating in either fluvial channels or distal flood strata within some cycles aeolian sand sheets are absent and fluvial deposits rest directly above aeolian dune facies the transitions from one facies association to another are abrupt and marked by erosive surfaces that delineate distinct episodes of sediment accumulation the origin of both the wetting upward cycles and the erosive surfaces was controlled by the ground water table level dry sand availability and aeolian and fluvial sediment transport capacity variations related to climatic fluctuations between relatively arid and humid conditions preservation of the fluvial aeolian deposits reflects an overall relative water table rise driven by subsidence

depth and modes of pliocene pleistocene crustal extension of the apennines italy since early pliocene times the apenninic chain has been dissected by normal faults propagating towards the adriatic foreland in the tyrrhenian sea extension involved deep crustal sections whereas in the central apennines downfaulted area it affected the shallow crust the tyrrhenian back arc domain is connected to the overall flexural retreat of the adriatic apulia plate in front of the apenninic collisional wedge in the outer apenninic belt thin skinned delamination and gravitational collapse occurred in the hanging wall of a thickened wedge overthrusting the uplifted buoyant crust of the apulia foreland differential sinking velocity of the foreland plate results from the inherited competence contrast between the rigid gargano apulia carbonate platform to the south and the low competence lithology of the pelagic sequence of the adriatic basin to the north during late messinian early pliocene times this palaeogeographical boundary acted as a lithospheric tear separating segments of the apulia plate subjected to different subduction modes

sand drift surfaces a neglected type of bounding surface sand drift surfaces are sharp generally erosional surfaces separating waterlaid deposits from overlying eolian sand sheet deposits they form in many modern playa lake ephemeral stream and alluvial fan environments but have rarely been reported from ancient sequences sand drift surfaces are an important type of bounding surface one which marks the transition from subaqueous to eolian depositional processes thereby providing valuable information for environmental reconstructions architectural element analysis and short and long term climate changes because of their nature sand drift surfaces cannot be described by existing bounding surface classifications to overcome some of the classification problems we suggest a simple nonhierarchical terminology

characterization of fault roughness at various scales implications of three dimensional high resolution topography measurements accurate description of the topography of active fault surfaces represents an important geophysical issue because this topography is strongly related to the stress distribution along fault planes and therefore to processes implicated in earthquake nucleation propagation and arrest to date due to technical limitations studies of natural fault roughness either performed using laboratory of field profilometers were obtained mainly from 1 d profiles with the recent development of light detection and ranging lidar apparatus it is now possible to measure accurately the 3 d topography of rough surfaces with a comparable resolution in all directions both at field and laboratory scales in the present study we have investigated the scaling properties including possible anisotropy properties of several outcrops of two natural fault surfaces vuache strike slip fault france and magnola normal fault italy in limestones at the field scale digital elevation models of the fault roughness were obtained over surfaces of 0 25 m2 to 600 m2 with a height resolution ranging from 0 5 mm to 20 mm at the laboratory scale the 3 d geometry was measured on two slip planes using a laser profilometer with a spatial resolution of 20 m and a height resolution less than 1 m

bounding surfaces in a mixed aeolian fluvial system rotliegend wessex basin sw uk the dawlish sandstone formation is a late permian succession of mixed aeolian and fluvial deposits in the wessex basin sw england it is used to illustrate two contrasting types of fluvial aeolian bounding surface planar and incised planar bounding surfaces separate tabular bodies of fluvial conglomerate and aeolian dune sandstone they were produced primarily by wind scour to groundwater table with the later emplacement of conglomerates resulting in local fluvial erosion of cemented aeolian dune sandstones incised bounding surfaces were produced by fluvial downcutting the erosive relief was infilled with mixed aeolian fluvial deposits the dawlish sandstone formation may provide the first outcrop example of these incised valley fills which have recently been identified as a major component of the subsurface rotliegend in the southern north sea basin the potential variability of aeolian fluvial sedimentary architecture has important implications for well to well correlation and reservoir modelling

evidence for 2 0 ga continental microbial mats in a paleodesert setting abstract early evolved microbial communities characterized the initial biological invasion of precambrian continental landscapes in modern arid settings microbial mats and biological soil crusts are well developed and stabilize sediment the paleoproterozoic makgabeng formation in south africa is one of the oldest and best preserved dryland systems on earth six types of microbial mat related structures are now recognized within these depositional systems this paper presents three newly discovered structures that include tufted microbial mat biological soil crusts and gas escape features in addition to three previously documented structures that include roll up features sand cracks and wrinkled features these discoveries demonstrate that microbial communities were well established and inhabited diverse continental settings by 2 0 ga approximately 200 million years after the onset of the great oxidation event

facies distribution as a response to early rift tectonic activity in the sergipe alagoas basin northeastern brazil abstract accommodation rates in rift basins are mainly controlled by tectonics however during early rift stages normal fault activity is dispersed and incipient which makes it difficult to recognize the effects of early crustal extension the sedimentary stacking pattern of rift related depositional environments can be decisive to address this question this paper aimed to evaluate the stratigraphic record of the tithonian berriasian serraria formation sergipe alagoas basin brazil which was deposited in the afro brazilian depression as a result of the early extension of west gondwana in total 14 lithofacies were described interpreted and arranged into 7 facies associations at the base of the formation bars and sand sheets were deposited by low discharge braided channels which were deposited on top of lacustrine mudstones of the bananeiras formation there is a change in stratigraphic architecture in the middle of the section where fluvial channels become deeper due to increasing discharge promoting an increase in grain size of the transported bedload and greater rates of coarse sand and gravel bar stacking rare crevasse channels and restricted aeolian dune fields occur adjacent to braided channel belts upwards the serraria formation becomes dominated by delta front and delta plain deposits the fluvial and aeolian facies associations represent a progressive decrease in accommodation while the upper fluvio deltaic interval means an increase in accommodation pointing to the early rift stage climax the fluvial caioba sandstone on top of the serraria formation indicates reestablishment of fluvial drainage either due to decreasing tectonism or due to low accommodation at the time of deposition thus the sedimentary stacking pattern of serraria formation represents higher frequency cycles within an early rift tectonic system tract

lower triassic sequence stratigraphy of the western part of the germanic basin west of black forest fluvial system evolution through time and space abstract the aim of this paper is to analyse the fluvial evolution of the lower triassic in the western part of the germanic basin through time and space as well as the impact of the geodynamic and climatic setting on the preservation of fluvial deposits the lower triassic crops out only in the vosges massif and the black forest so well log studies are required to realise sequence stratigraphy correlations and establish comparisons with others parts of the germanic basin in a first step we use well log data analyses to characterise the electrofacies associations in the triassic and then define the well log signatures of each formation in a second step the characterisation and recognition of genetic sequences and their stacking pattern allow us to define seven minor cycles integrated into two major cycles finally the quantification of the lithologies at different stages of basin evolution leads to the reconstruction of paleoenvironmental maps to illustrate facies evolution through space and time a comparison with cycles defined in the germanic basin allows us to propose correlations of the lower triassic on either side of the rhine graben and leads to a discussion of the evolution of fluvial systems through time and space during the scythian the fluvial style is characterised by braided fluvial systems evolving laterally into lake deposits towards the central part of the germanic basin during this stage the basin was a huge depression with very few marine connections in its extreme eastern part the stratigraphic cycles represent rhythmic fluctuations in relative lake level that could be attributed to sediment supply and or lake level variations in an arid setting four minor stratigraphic cycles are observed that are integrated within a single major stratigraphic cycle during the period of the stratigraphic base level rise of the major cycle a maximum of 233 m of sediment would represent a duration of sedimentation in the paris basin of at least 1 8 m y during the period of the stratigraphic base level fall of the major cycle a maximum of 65 m of sediment would have accumulated over 2 5 m y on the western edge of the germanic basin the top of the scythian is marked by a major sedimentary break characterised by a planation surface with preservation of the first paleosols followed by the hardegsen unconformity this unconformity is tectonically deformed leading to the development of a new sedimentation area in the west of the basin the fluvial sedimentation above this discontinuity shows a trend towards enhanced development of floodplain or lacustrine type environments at its western margin with the formation of paleosols the fluvial systems are linked with sabkhas and then with a shallow sea connected to the tethys ocean in this context the stratigraphic cycles are caused by variations in relative sea level and or sediment supply the fluvial deposits are preserved in an exoreic basin

development of n w europe s southern permian gas basin summary the southern permian basin contains over 4 1 10 12 m 3 of recoverable non associated gas most of which is found in early permian rotliegend sandstones the most important source of this gas is carboniferous coal deposited in a proto tethys foredeep basin where the coals were overlain by rotliegend desert sands and by late permian zechstein halite the scene was set for creating important reservoirs for gas deformation of the reservoir and seal to create a trap and the generation and migration of carboniferous gas resulted from the structural history of the area which was shaped in part by underlying crustal blocks and zones of crustal weakness much of this history was related to events most clearly expressed beyond the limits of n w europe in the north atlantic and tethys 1 e w tension which gave rise to the oblique slip induced subsidence of many sub basins within the southern permian basin caused the consecutive creation of the viking central graben system and rockall trough and ended with the crustal spreading of the atlantic ocean and 2 the early mesozoic opening of tethys its cretaceous closure and ensuing alpine orogeny which induced inversion in many areas of the southern permian basin that are now gas bearing

scaling of the shear rupture process from nucleation to dynamic propagation implications of geometric irregularity of the rupturing surfaces a series of systematic high resolution laboratory experiments have been performed on the nucleation of propagating slip failure on preexisting faults having different surface roughnesses to demonstrate how the size scale and duration of shear rupture nucleation are affected by geometric irregularity of the rupturing surfaces on the basis of the experimental results it has been discussed theoretically how consistently scale dependent physical quantities inherent in shear rupture are scaled the experiments led to conclusive results that the nucleation process consists of two phases phase i an initial quasi static phase and phase ii a subsequent accelerating phase and that the nucleation process is greatly affected by geometric irregularities on the rupturing surfaces in phase i the rupture grows at a slow steady speed which is independent of the rupture growth length l in contrast during phase ii the rupture develops at accelerating speeds v which increase with an increase in l obeying a power law v vs l c n where vs is the shear wave velocity c is the characteristic length representing the geometric irregularity of the fault surfaces and and n are constants 8 87 10 29 and n 7 31 scale dependency of scale dependent physical quantities including the nucleation zone size and its duration is commonly ascribed to scale dependency of the slip dependent constitutive law parameter dc which is in turn governed by c it has been discussed that a unified comprehension can be provided for shear rupture of any size scale if the constitutive law for shear rupture is formulated as a slip dependent law

straightforward reconstruction of 3d surfaces and topography with a camera accuracy and geoscience application topographic measurements for detailed studies of processes such as erosion or mass movement are usually acquired by expensive laser scanners or rigorous photogrammetry here we test and use an alternative technique based on freely available computer vision software which allows general geoscientists to easily create accurate 3d models from field photographs taken with a consumer grade camera the approach integrates structure from motion sfm and multi view stereo mvs algorithms and in contrast to traditional photogrammetry techniques it requires little expertise and few control measurements and processing is automated to assess the precision of the results we compare sfm mvs models spanning spatial scales of centimeters a hand sample to kilometers the summit craters of piton de la fournaise volcano with data acquired from laser scanning and formal close range photogrammetry the relative precision ratio achieved by sfm mvs measurement precision observation distance is limited by the straightforward camera calibration model used in the software but generally exceeds 1 1000 i e centimeter level precision over measurement distances of 10s of meters we apply sfm mvs at an intermediate scale to determine erosion rates along a 50 m long coastal cliff seven surveys carried out over a year indicate an average retreat rate of 0 70 0 05 m a 1 sequential erosion maps at 0 05 m grid resolution highlight the spatio temporal variability in the retreat with semivariogram analysis indicating a correlation between volume loss and length scale compared with a laser scanner survey of the same site sfm mvs produced comparable data and reduced data collection time by 80

the interaction of aeolian and fluvial processes during deposition of the upper cretaceous capping sandstone member wahweap formation kaiparowits basin utah u s a abstract detailed examination of the upper cretaceous capping sandstone member of the wahweap formation in the kaiparowits basin utah reveals the presence of aeolian stratification deposition by aeolian processes is recognized and distinguished from subaqueous deposition by the presence of centimeter scale inversely graded wind ripple stratification the aeolian stratification in the wahweap formation is the first occurrence reported from upper cretaceous strata on the colorado plateau of the western u s a aeolian stratification occurs as thin wind reworked caps of fluvial bar sandstones deposited within low sinuosity braided streams and as more extensive deposits of small scale dunes that developed in geographically restricted dune fields aeolian reworking of bars took place during low stage flow and was possibly controlled by intermittent seasonal discharge variations prolonged aridity led to increased sand supply entering the aeolian system dunes nucleated and grew rapidly between the braided stream systems these small scale dunes rarely developed extensive or tall slip faces as evidenced by the rare preservation of grain flow strata and the dominance of wind ripple stratification the dune field was characterized by sinuous crested dunes probably barchans amid and linked to the extensive braided stream systems based on modern analogs the resulting change in sand storage supply probably is related to a short term shift to a more semi arid arid climate possibly seasonally however a longer term climate change to semi arid arid may be indicated for the dune complex near the boundary with the overlying kaiparowits formation

the minimum scale of grooving on faults at the field scale nearly all fault surfaces contain grooves generated as one side of the fault slips past the other grooves are so common that they are one of the key indicators of principal slip surfaces here we show that at sufficiently small scales grooves do not exist on fault surfaces a transition to isotropic roughness occurs at 4 500 mm although the scale of the transition can vary even between locales on a single fault the aspect ratio of the roughness at the transition is well defined for a given fault we interpret the transition between grooved and ungrooved scales as a transition in deformation mode of asperities on the slip surface grooves can form when a hard indenter slides past a softer surface at small scales the asperities appear to yield plastically and therefore do not generate grooves as hard indenters the plastic yielding can be a consequence of the high shear strains required to deform the surfaces at small scales where the aspect ratio roughness is high the transition to plastic yielding is predicted to occur at a specific aspect ratio for each fault as observed the new observation both shows a limit to one of the most commonly observed features of faults and suggests a change in the mode of failure of faults as a function of scale 2016 the authors