release fault a variety of cross fault in linked extensional fault systems in the sergipe alagoas basin ne brazil abstract two types of cross faults are herein recognized transfer faults and the newly termed release faults transfer faults form where cross faults connect distinct normal faults and horizontal displacements predominate over vertical ones in contrast release faults form where cross faults associated with individual normal faults die out within the hangingwall before connecting to other normal faults and have predominantly vertical displacements release faults are geometrically required to accommodate variable displacements along the strike of a normal fault thus they form to release the bending stresses in the hangingwall and do not cut normal fault planes nor detachment surfaces at depth release faults have maximum throws adjacent to normal faults and may be nearly perpendicular or obliquely oriented to the strike of the latter such geometry appears not to depend upon pre existing weaknesses but such variable orientation to normal faults is an inherent property of release faults release faults commonly appear as simple normal faults in seismic sections without implying extension along the strike of rift and basins three dimensional strain deformation occurs in the hangingwall only between the terminations of an individual normal fault but regionally release faulting is associated with plane strain deformation in linked extensional fault systems

relay zone geometry and displacement transfer between normal faults recorded in coal mine plans abstract overlap lengths separations and throw gradients were measured on 132 relay zones recorded on coal mine plans throws on the relay bounding fault traces are usually 2 m and individual structures are recorded on only one seam throw gradients associated with relay zones are not always higher than on single faults but asymmetry of throw profiles is diagnostic of relay zones bed geometries around larger faults in opencast mines are used to assess the displacement accommodated by shear in the vertical plane normal to the faults and displacement transfer accommodated by shear in the fault parallel plane three dimensional structure is defined for two relay zones each recorded on five seam plans these relay zones are effectively holes through the fault surfaces and overlap occurs between salients or lobes of the parent fault surfaces lobes initially terminated at tip lines but as the faults grew gradually rejoined the main fault surfaces along branch lines this type of relay zone originates by bifurcation of a single fault surface at a locally retarded tip line and is an almost inevitable result of a tip line irregularity

high resolution fault displacement mapping from three dimensional seismic data evidence for dip linkage during fault growth abstract detailed mapping using high resolution three dimensional seismic data has revealed a number of sub horizontal anomalies in the distribution of vertical displacement throw on the planes of growth faults in the gulf of mexico recognition of these anomalies is highly sensitive to the interval at which the fault displacements are sampled because they represent local decreases in throw which are confined to small discrete parts of the fault planes the distribution of the anomalies is inconsistent with model displacement fields of quasi elliptical concentric contours and is therefore incompatible with models of fault growth by uniform slip distribution and radial tip line propagation an alternative model is proposed whereby the evolution of a fault plane is established by the propagation and linkage of precursor fault segments in the dip direction dip linkage overlap and linkage of fault tips in the dip direction results in relay structures that are sub parallel to fault strike and therefore displacement minima that are sub horizontal on normal and thrust faults however since they are orthogonal to the main slip direction on the fault these structures have a low preservation potential and are therefore unlikely to be well resolved on cross sectional seismic profiles

effect of mechanical interaction on the development of strike slip faults with echelon patterns abstract the overlapping geometry of echelon strike slip faults is well known we have quantified this observation by measuring the amount of overlap and separation and plotting them against each other for over 120 examples although there is large scatter the data show a linear trend suggesting that the overlap increases proportionally with separation up to a limiting value we have analyzed this conspicuous relationship in terms of fault interaction by using a numerical model based on displacement discontinuity the results show that fault interaction is in fact an important factor in contributing to the overlapping geometry of echelon strike slip faults

transverse versus longitudinal extension in the foredeep peripheral bulge system role of cretaceous structural inheritances during early miocene extensional faulting in inner central apennines belt this study reports on the rocca di cave extensional fault system which is located in the prenestini mountains central italy of the apennines fold and thrust belt and presently represents the oldest exposure of early orogenic foreland fault system of the apennines this fault system was oriented perpendicular to the strike of the foredeep peripheral bulge system indicating that the onset of convergence was marked by a foredeep parallel extension instead of the commonly observed foredeep perpendicular stretching associated with lithosphere flexuring the studied fault system is formed by a 10 km long and 2 km wide e w elongated area that includes two mutually orthogonal sets of faults oriented about e w and n s respectively e w and mainly n s striking faults developed during a preorogenic santonian to campanian in age e w oriented extension kinematics which caused first uplift and erosion and then drowning of the cretaceous carbonate platform and the onset of a pelagic environment both fault sets were later reactivated in the early miocene when the area was forming part of the foreland region ahead of the eastward migrating apennines fold and thrust belt and was undergoing local n s oriented i e foredeep parallel stretching this extensional stage implied the sedimentation of hundreds of meters of synkinematic strata in the northern block of the rocca di cave fault system coevally with episodes of subaerial erosion in areas of the southern block further extensional and right lateral reactivation of inherited faults occurred in the late miocene during the progressive incorporation of the area into the apennines belt

the complete apennines orogenic cycle preserved in a transient single outcrop near san fele lucania southern italy orogenic cycles may be viewed as comprising two extensional stages that are separated by a stage of contraction this sequence has characterized the evolution of most mountain belts resulting from continental collision and the structural signature of individual stages is recognized on a wide variety of scales i e from microscopic to regional whereas the history of mountain belts is generally inferred from observations carried out at different sites the entire sequence of deformation is very rarely recorded in single exposures the double switch in tectonic regime that led to the development of the lucanian apennines in southern italy from pre orogenic drifting through synorogenic thrusting to post orogenic extension is preserved in a superb metre scale outcrop at serra manarella in the vicinity of san fele a late jurassic synsedimentary normal fault is sealed by strata affected by a mid pliocene thrust related fold this composite structure in turn is truncated by a mid pleistocene normal fault observation of these relationships represents a unique opportunity to unequivocally establish the relative chronology of deformations in the lucanian apennines and may provide useful constraints for regional cross section restoration

relay ramp forms and normal fault linkages canyonlands national park utah fieldwork within a series of mesoscale grabens in southeast utah has revealed a particularly well exposed system of interlinked extensional faults a series of down faulted grabens are developed within a 460 m thick brittle layer of upper paleozoic sandstone and shale which overlies a ductile layer with a high gypsum content all the major grabens consist of two or more overlapping elements which are composed of fault segments these segments may be hard linked fault surfaces are joined or soft linked fault surfaces are isolated but linked by ductile strain of the rock volume between them in map view relay structures are defined as zones connecting the footwalls and hanging walls of overlapping fault segments representing soft linkage of fault segments in the canyonlands grabens the transfer of displacement between soft linked fault segments is characterized by well de fined dipping relay ramps commonly rotated and extended to accommodate the ductile strain between the overlapping fault segments relay ramps develop as ephemeral structures eventually becoming breached by hard linkage of the fault segments breakdown of ramps by breaching is part of the process of fault growth by segment linkage within the canyonlands graben system four orders of segmentation are present this may be a consequence of different scales of mechanical heterogeneity but evidence from the canyonlands grabens and elsewhere points to a fundamental process of discontinuous fault growth by segment linkage

stratigraphic and structural relationships between meso cenozoic lagonegro basin and coeval carbonate platforms in southern apennines italy abstract stratigraphic studies and facies analysis integrated with a new geological and structural survey of the meso cenozoic units outcropping in the campania lucania apennines southern italy allowed us to restore the palaeogeographic pattern and the tectonic evolution of the chain during oligo miocene times the southern apennines are a n150 striking and ne verging fold and thrust belt mainly derived from the deformation of the african apulian passive margin four wide belts with different features have been recognized in the chain area from east to west the following units outcrop a successions characterized by basinal to marginal facies ranging in age from cretaceous to miocene tectonically lying on plio pleistocene foredeep deposits b successions characterized by shallow water basinal and shelf margin facies ranging in age from middle triassic to miocene lagonegro units overthrust on the previous ones c triassic to miocene carbonate platform successions apenninic platform units overthrust on the lagonegro units d jurassic cretaceous to miocene deep water successions ophiolite bearing or internal units and associated siliciclastic wedges outcropping along the tyrrhenian belt and the calabria lucania boundary overthrust on the apenninic platform units all these units tectonically lie on the buried apulian platform which is covered at least in the eastern sector of the chain by pliocene to pleistocene foredeep deposits stratigraphic patterns of the cretaceous to lower miocene lagonegro successions are coherent with the platform margin ones calcareous clastics of the lagonegro basin are in fact supplied by an adjacent western platform as inferred by several sedimentological evidences slump and palaeocurrent directions and decreasing grain size towards the depocentre of the basin tectonic relationships among the different units of the chain with particular emphasis on the lagonegro and apenninic platform units of the lucanian segment are shown by means of both regional and detailed geological cross sections the lagonegro units constantly underlie the carbonate units originating from detachment and thrusting of the western platform and overlie the eastern i e apulian platform the lagonegro units show a strong lateral variability of map scale structures dome and basin folds are in fact largely observable in the lucanian apennine further the belt is widely affected by plio quaternary strike slip and extensional faults yet excluding the brittle deformation due to quaternary faulting the complexity of structural styles seems to result from the neogene refolding of more ancient structures produced by oligo miocene intraplate deformation this hypothesis is supported by two independent lines of evidence the first is the recognition of unconformities between the lower miocene numidian sandstone and the underlying lagonegro successions at least in the southwestern sectors the second is that the internal i e western platform remains undeformed until the early miocene both stratigraphic and structural data suggest an external position of the meso cenozoic lagonegro basin with regard to the coeval apenninic platform

low angle normal faulting and focused exhumation associated with late pliocene change in tectonic style in the southern apennines italy in the southern apennines low temperature thermochronometry data indicate that exhumation of previous tectonically buried sedimentary units started at around 10 ma and took place mostly during the last 6 ma relatively high exhumation rates are obtained from apatite fission track aft and u th he ahe analysis pointing to a substantial contribution of tectonic processes to rock exhumation besides erosion exhumation rates derived from new apatite u th he data ahe for the last 3 ma are generally lower than rates determined by aft data and almost in line with erosion rates inferred from cosmogenic nuclides and sediment yield thus suggesting that tectonic exhumation was dominant during the older exhumation stages of this region however younger cooling ages in the monte alpi area from both aft and ahe analyses point out focused exhumation during the last 3 ma structural and morphotectonic analyses indicate that fast exhumation occurred specifically in this area where the apulian platform reservoir carbonates elsewhere buried beneath a several kilometer thick allochthonous cover are exposed at the surface as a result of a complex interplay between steep rooted reverse faulting and shallow low angle extension this deformation involved the development of foreland dipping low angle normal faults affecting the allochthonous cover units during the late stages of reverse fault related anticlinal growth in the underlying buried carbonates extension of the region triggered focused exhumation in the footwall of the extensional low angle faults which was followed by widespread crustal extension and associated development of high angle normal faults leading to surface uplift of monte alpi

the origin of the apenninic arcs abstract the apennine area is composed of a variety of arcs some of them forming the mountain chain and some of them being submerged below the po plain and the adriatic sea the structure of the apennine mountain belt is that of a succession of northeast east and southeastward directed arcs corresponding to single thrust sheets each arc is limited by n s oriented dextral transcurrent faults data from volcanology gravimetry and reflection seismic surveys show that an important section of the upper mantle is involved in these features the geodynamic reconstruction during neogene times i e the period of apenninic up building suggests that a unique arc existed from oligocene to middle miocene times as a result of the rotation of the sardo corso continental block this arc was successively disrupted in several segments which advanced and shortened differentially as a function of the resistance to the orogenic expansion opposed by the rigid adriatic foreland this new tectonic phase which is responsible for most of the apenninic features has been triggered by the differential evolution of anomalous mantle domes in the tyrrhenian area from post middle miocene times onwards

fault growth mechanisms and scaling properties in foreland basin system the case study of monte alpi southern apennines italy abstract the present work focuses on the comprehension of the growth mechanisms and dimensional properties of the pre pliocene monte alpi fault network by mean of integrated field and laboratory analyses after this multidisciplinary approach detailed throw profiles are computed for each fault belonging to the monte alpi network subsequently the dimensional properties of the individual faults are calculated data obtained from this work are discussed in terms of fault growth mechanisms and timing of deformation and reported in a conceptual tectonic evolution model of the messinian foreland basin system data suggest that originally isolated fault segments developed during the earliest stages of foreland basin formation by re activation of a pre existing early cretaceous fault set and formation of an orthogonal one these two fault sets formed a scale independent network differently the same fault sets were also active during its subsequent development forming a scale dependent fault network characterized by t and y shaped fault intersections this deformation controlled the half graben depocenters evolution filled by up to ca 600 meters of terrigenous deposits during the late messinian time

tectonic model and three dimensional fracture network analysis of monte alpi southern apennines abstract the monte alpi southern italy is well known as an outcropping analogue of the val d agri subsurface units which host a number of oil fields of economic importance this paper presents an example of a detailed study which integrates stratigraphy structural geology tectonic analysis and fracture network study the new structural model presented is based on a detailed 1 12 500 field survey of the area whose results are illustrated in a comprehensive outcrop map geological map and structural cross sections and stereographic projections and palaeostress inversion calculations of a mesostructural data set the monte alpi unit is characterised by a 2000 m thick sequence of jurassic cretaceous platform carbonates conformably covered by middle upper miocene calcarenites this sequence is unconformably covered by upper messinian terrigenous clastics mainly along a number of major growth faults our detailed mapping revealed that the monte alpi unit is tectonically overlain by the lagonegro basinal unit thin siliceous carbonates and remnants of pelagic pelitic and carbonate deposits all highly deformed and by the monte la spina unit cataclastic mesozoic carbonates and dolomites this solves earlier raised questions concerning the palaeogeographic provenance of the carbonates outcropping in the area which can thus without any doubt be correlated with the external carbonate domains known from the subsurface the present day structure shows a structural inversion along the major late miocene growth faults which acted as sinistral transpressive faults the latter faults are part of a regional set dissecting the southern apennines active up till at least middle pleistocene times a fracture study was performed on the mesozoic carbonates of the area in order to collect data regarding length distribution orientation density and spatial heterogeneity of the fracture network to be used for considerations regarding exploration and development of the val d agri reservoirs the data were collected on 37 horizontal strata parallel and vertical outcrop surfaces through photographic restitution and digitising of fracture lineament traces and measurements of orientations of all visible fractures furthermore three major outcropping rock walls along the flanks of monte alpi and santa croce were photographed and fracture and fault zone lineaments were digitised all data were inserted and calibrated in a three dimensional 3d geographic information systems and computer aided design giscad environment consisting of a database and a 3d geographical framework comprising topographic map digital terrain model dtm geological map aerial photograph lineament map and a 3d reconstruction of major fault surfaces making use of the potential of the 3d working environment outcrop surfaces and rock walls were reconstructed at their correct 3d position and orientation data analysis comprised stereographic contour diagrams and rosette diagrams of 1800 fracture orientations in order to recognise main fracture sets three corrections were performed on these data length weighting terzaghi correction removal of sample orientation bias and tilt removal from a comparison between orientation data on various scales combined with field evidence it can be deduced that fault and fracture sets are part of the same structural pattern and that fracture sets were generated prior to plio pleistocene tectonics and passively rotated fracture and fault length distribution was analysed by the generation of diagrams which plot cumulative frequency versus length in log log space normalising for area of observation these diagrams composed of about 30 000 measurements and constituting the most complete data set presented in the literature up till now show that small scale and large scale features form part of one scale invariant system with fractal properties no scale gap is present in our data set which comprises rock wall data in the subseismic scale range it appears that the 3d fracture network can best be described by a fractal dimension of 2 98 and a coefficient of 0 25 the outcome of the study places important constraints on fracture network simulation exercises in hydrocarbon reservoir simulation studies which use numerical input parameters in order to make predictions of the tectonic texture present in the subsurface

structural interpretation of hydrocarbon traps sealed by basement normal block faults at stable flank of foredeep basins and at rift basins closures sealed by basement normal block faults are most commonly formed by a grid of faults with multiple orientations and by a favorable dip of the reservoir strata hydrocarbons are trapped updip by structural upturns along the edge of the downdropped blocks or at the upthrown or downthrown edge of blocks where block tilt is away from the sealing faults closure parallel with reservoir strike is provided by 1 updip junction of primary oblique or oblique and longitudinal block bounding faults 2 internal secondary faults that trend transverse or oblique to the block boundaries 3 positive bend of reservoir strata 4 plunge of block edge folds and or 5 stratigraphic terminations of the reservoir fault seal upward along the faults is most likely where a thick section of impervious strata above the reservoir is in contact with itself across the fault or where the fault does not extend upward into shallower permeable zones seal across the fault surface is most certain where impermeable rocks are laterally juxtaposed against the reservoir impervious material within the fault zone such as shaly smear gouge cataclastic gouge mineral deposits and asphalt or tar impregnations can be effective barriers where reservoir facies are juxtaposed across the fault the traps can form a major hydrocarbon play on the stable shelves of foredeep or foreland basins as demonstrated by the san joaquin valley and eastern venezuela basins the traps provide secondary prospects in rift basins uch as the viking graben and vienna basin

structural evolution of the lucanian apennines southern italy abstract in this paper we present a study of an entire segment of the southern apennines of italy extending from the pollino mountain range to the south to the agri valley to the north in which all the units of the chain are represented combining regional information with detailed structural data obtained from the different tectonic units forming the orogenic belt the structure as well as the tectonic evolution of this portion of the orogenic belt are proposed the overall architecture of this segment of the southern apennines mountain chain represents the result of a complete orogenic cycle in which oceanic subduction syn collisional and post collisional events are well recorded structurally this segment of the orogenic belt exhibits two distinct structural levels separated by a major detachment surface the sole thrust of the accretionary wedge that occur at the surface in the allochthonous nappes and at depth in the adria continental margin the upper level is characterized by an imbricated fan system affecting the allochthonous terranes emplaced during oceanic subduction and the first stages of continent continent collision the lower level is represented by a duplex geometry that has developed in the post collisional stage during evolution of the foreland migrating thrust system involving the carbonate platform basin system of the adria block during the last stages of the mountain building process when the foreland thrust migration was locked by the thickening of the colliding continental crusts the southern apennines were thus affected by a severe strike slip tectonics that dissects the entire mountain belt deeply modifying the previous thrust geometry

subduction platform subsidence and foreland thrust loading the late tertiary development of taranaki basin new zealand borehole seismic and gravity data are used to investigate deformation of continental lithosphere at a miocene collisional zone deformation is manifested in the three following principal forms a long wavelength 500 km platform subsidence ascribed to mantle convection flexural deformation on a scale of 100 200 km due to crustal thrusting at the eastern boundary of the taranaki basin and a ductile thickening evident on the deep seismic section of taranaki basin that occurs on a scale of 10 km evidence for flexural deformation principally comes from the deep seismic section that shows a 150 km wavelength bending of the moho down toward the major zone of thrusting within the taranaki fault zone paleowater depths however provide evidence for an initial early miocene regional subsidence that is too long in wavelength to be explained by flexure induced from thrust sheet loading instead we propose that this broad platform subsidence was driven by loading from a deep source probably subduction induced flow in the mantle by 22 19 ma 1 2 km of water existed over most of the area now occupied by south taranaki basin by 19 17 ma the water depth in the zone east of the taranaki basin the taranaki fault zone had been replaced by rock due to submarine thrusting and crustal thickening this build up of submarine topography in the taranaki fault zone constitutes part of the load 25 8 mpa that created and maintains south taranaki basin gravity data place further constraints on loading at the thrust front and point to an additional intracrustal loading equivalent to 15 7 mpa over a 50 km wide zone this intracrustal load is explained as being due to thick skinned thrusting bringing denser lower crustal rocks nearer to the surface in the thrust zone the complete load on the taranaki foreland is therefore in three parts the submarine topographic load the intracrustal load and the loading of infilling sediments

tectono stratigraphic and kinematic evolution of the southern apennines calabria peloritani terrane system italy abstract temporal controls such as sedimentation ages in foredeep and wedge top basins combined with information about stratigraphic and metamorphic evolution ages and characterization of magmatic rocks deep structures burial and exhumation histories allowed us to obtain kinematic estimations of the southern apennines calabria peloritani terrane system evolution from the late oligocene to recent calculated thrust front velocities suggest to subdivide the orogenic evolution in main five kinematic stages characterized by different velocity trends nine kinematic complexes from a to i i e sets of tectonic units deformed in the same time range are determined according to foredeep ages these complexes bounded by main regional thrust faults encompass one or more tectonic sub units and successions of different paleoenvironment domains paleogeographic evolution model indicates according to available paleomagnetic data a counterclockwise rotation with a mean angle of 60 for the apennine platform carbonates whereas a mean angle of 20 for the eastern sector of the apennine platform and western side of apulian platform shortening estimations for the apennine successions show values ranging between 55 and 88 and a linear best fit indicating an increase from 60 nw sector to ca 90 se sector such high values are consistent with a deformation dominated by a thin skinned tectonics on the contrary the low value of 28 calculated for mt alpi suggests an exhumation ruled by high angle deep seated structures characterized by limited displacements tectonic vergences referred to middle late miocene late miocene and pliocene middle pleistocene when restored indicate an average eastward tectonic transport finally tectonic evolution is summarized in eleven schematic cross sections and corresponding paleogeographic maps

the liguride complex of southern italy a cretaceous to paleogene accretionary wedge abstract the ophiolite bearing allochthonous flysch liguride complex of the southern apennines italy has traditionally been divided into two tectonic units the metamorphic frido unit and the unmetamorphosed cilento unit the two units have hitherto been considered to derive from two distinct paleogeographic domains however the identification of cilento unit sediments within frido unit successions implies that the sediments of both units were coeval deposits within the same sedimentary basin cilento unit sediments also occur as the sedimentary cover of kilometre scale oceanic slices within the liguride complex indicating deposition on oceanic basement and not continental basement as was previously considered thrust transport directions and sediment provenance indicate that during late jurassic time this ocean basin lay to the east of the calabrian terrain and to the west of apulia calabria and apulia representing the european and african margins of neotethys respectively northwestwards subduction of oceanic crust beneath the calabrian terrain from late cretaceous time onwards produced an accretionary wedge which was later emplaced onto the apulian margin during the burdigalian collision of calabria and apulia the liguride complex represents the obducted remains of this accretionary wedge this interpretation contains three important implications for pre tertiary plate tectonic reconstructions of the western mediterranean region these are 1 1 the calabrian continental terrain formed part of the iberian plate on the north margin of neotethys this may have implications for the former location and continuation of the north pyrenean fault 2 2 the existence of a continuation of the eo alpine belt through calabria and the kabylies is placed in doubt thus requiring only one constant polarity nw dipping subduction direction to explain the structures now seen in these regions 3 3 the existence of a transform fault between the europe vergent structures of corsica and the africa vergent structures of calabria this transform must have been active from at least late cretaceous time in a position now occupied by the tyrrhenian sea

osl based lateral progradation and aeolian sediment accumulation rates for the apalachicola barrier island complex north gulf of mexico florida article i nfo vertical sediment cores in five separate beach ridge complexes along the north east gulf of mexico coast were recovered and dated using optically stimulated luminescence osl dating of quartz these are located on cape san blas csb little st george island lsgi richardson s hammock rh st joseph peninsula sjp and saint vincent island svi all of these landforms are coastal barrier systems situated along a 100 km stretch of the florida panhandle u s a two samples were collected for dating from each core ridge accumulation rates rar associated with lateral progradation were calculated from the dated samples we also determined average sediment accumulation rates asar for two intervals within each sediment core all osl ages within the sediment cores were found to be in stratigraphic order or in a few cases statistically indistinguishable moreover all dated ridges were found to be in correct temporal sequence based on their geomorphic positions rapidly accreted sequences were found to be backed by st joseph bay in the western region of the study area more slowly accreted sequences were associated with the more eastern stretches of the study area backed by st vincent sound and apalachicola bay our asar results are in accord with an australian study of modern dune accumulation perhaps our most important finding is that in the barrier island environments of this north eastern gulf coast region aeolian sedimentation continues well after full vegetative cover develops and stranding of landward ridges takes place this confirms our similar earlier observation on svi lopez and rink 2008 we find that up to approximately one order of magnitude lower sedimentation rates occur after an initial period of more rapid aeolian accumulation for the vertical intervals studied in foredune ridges lateral progradation rates of ridge sequences were highly variable within the study area ranging from 92 to 848 m 100 years but we did find agreement between some of our slower ridge accumulation rates and those in other areas of florida and around the world determined using osl and 14 c dating we conclude that osl may be used in a regional context to establish variation in progradation rates and aeolian accumulation that varies among systems

a review of deformation pattern templates in foreland basin systems and fold and thrust belts implications for the state of stress in the frontal regions of thrust wedges aesthetically appealing thrust systems and related large scale anticlines in both active and fossil foreland fold and thrust belts and the economic potential associated with the m have captured the interest of structural geologists for many decades as a consequence a large amount of data on sub seismic deformation patterns from thrust related an ticlines is available in the literature we provide a review of deformation pattern templates from fi eld data in foreland fold and thrust belts and show that the most frequent tre nds of sub seismic syn orogenic deformation structures hosted in km scale thrust related folds frequently and pa radoxically indicate a syn th rusting strike slip stress fi eld con fi guration with a near vertical 2 and a sub horizontal 3 rather than a contractional one where the latter is expected to be the vertical principal axis of the stress ellipsoid this a pparent inconsistency between sub seismic syn orogenic deformation structures and stress fi eld orientation is here named the 2 paradox field data support a possible expla nation of the paradox provided by the major role played by i nherited early orogenic extensional deformation struc tures on thrust fault nucleation nucleation of major thru sts and their propagation is facilitated and driven by the positive inversion and linkage of the early orogenic sub s eismic extensional inheritance developed in the foreland basin this process eventually leads to the development of l argereversefaultzonesandcanoccurbothincontractional and strike slip stress fi eld con fi gurations

transpressive inversion of a mesozoic extensional forced fold system with an intermediate decollement level in the basque cantabrian basin spain 1 in the basque cantabrian basin spain normal faulting and associated folding occurred during late jurassic to early cretaceous rifting cenozoic pyrenean thick skinned transpressive inversion in the western parts of the basin preserved the first order extensional architecture integration of geological maps and seismic profiles has permitted to fully constrain the style of extensional deformation and subsequent inversion in the western portion of the basque cantabrian basin extensional faults offset the paleozoic basement up to lower triassic rocks the presence of an efficient decollement level represented by triassic evaporites produced the decoupling between basement rocks and the upper triassic to middle jurassic prerift cover sequence extensional forced folding occurred in the cover driven by basement faulting and the migration of evaporites toward the hanging wall of the extensional faults with salt welds developing away from them upper jurassic to lower cretaceous syn rift sediments deposited synchronously with forced folding which led to the development of extensional growth geometries associated with both master faults and nearly transverse faults syn rift growth sequences are characterized by downlap and onlap relationships with the underlying prerift units interpreted as the result of along strike variations of master fault extensional displacement rate cenozoic pyrenean contraction generated the right lateral transpressive inversion of basement master faults and the almost dip slip reactivation of transverse extensional faults

inelastic yielding and forebulge shape across a modern foreland basin north west shelf of australia timor sea the timor trough is a modem underfilled fore land basin created by partial subduction of the outer north west continental shelf of australia beneath timor island in the outer banda arc of eastern indonesia during the cenozoic a change of the effective elastic thickness eet of the continen tal foreland lithosphere from 80 20 km to 25 km over a distance of 300 km explains 1 the high curvature 10 m on the outer trough wall 2 the low shelf forebulge 200 m as measured along a reference base pliocene unconformity and 3 observed gravity an inelastically yielding quartzite quartz diorite dunite continental rheology can explain the eet gradient new shallow crustal 8 km seismic reflection im ages indicate that jurassic basement normal faults are reacti vated during bending of the foreland

slip distributions on intersecting normal faults abstract slip distributions on normal faults often are asymmetric and display multiple local maxima numerically computed slip distributions from elastic models indicate that such irregular slip distributions can be caused by mechanical interaction between intersecting faults that produce local perturbations of the stress field resolved on the faults a three dimensional boundary element model based on the displacement discontinuity method has been used to analyze the mechanical interaction of faults that form y or t shaped intersections slip distributions are asymmetric with a steeper slip gradient toward the line of intersection multiple slip maxima occur depending on the angle between the faults but generally they are not located along the intersections nor at the fault centers examples of intersecting normal faults taken from oil reservoir seismic surveys and sandbox experiments have been used to confirm the application of the theoretical results despite considerable simplifications in terms of geometry and boundary conditions the computed slip distributions capture the characteristics of the observed slip distributions

formation of regional cross fold joints in the northern appalachian plateau abstract fold axis parallel elongation associated with the development of arcuate fold and thrust belts is proposed as a causal mechanism for syn orogenic cross fold joints such a mechanism can be coupled with other joint propagation models providing a widely applicable resolution to the enigmatic origin of regional systematic joints the fold axis parallel elongation model is compatible with kinematic indicators as recorded by a sequence of cross fold joints and related deformational fabrics in the central and northern appalachian plateau modeling of an arcuate tectonic boundary subjected to normal compressive loading demonstrates that tangential tensile stress can be large enough to initiate cross fold joints on the convex side of the tectonic boundary simulated stress trajectories from boundary element modeling bear a strong resemblance to the stress trajectories inferred from the regional cross fold joint patterns in the central and northern appalachian plateau modeling also displays a cratonward decrease in both the tangential stress and the tangential strain such a decrease is consistent with the deformation styles observed in the central and northern appalachian plateau

regional exploration for channel and playa uranium deposits in western australia using groundwater abstract shallow calcrete aquifers in the central north of the yilgarn craton in western australia are the host to numerous secondary carnotite u deposits sampling and analysis of approximately 1400 shallow aquifer groundwaters were conducted to test if u mineralisation of this type may be found using a 5 km sample spacing results show this can be achieved all the economic deposits and most of the minor deposits and occurrences are associated with groundwater that has carnotite kuo2vo4 approaching or exceeding saturated conditions soluble u concentrations alone identified the largest deposit yeelirrie and several smaller deposits but this parameter was not as successful as the mineral saturation indices palaeodrainage distribution and thickness of cover combined with surface drainage and catchment boundaries provided background information of u primary sources and for areas with the highest exploration potential for channel and playa u deposits granites in the se of the study area are less prospective with regard to secondary u deposits groundwater geochemistry in conjunction with palaeodrainage mapping may greatly improve exploration through cover where radiometric geophysics is not effective the study of regional shallow groundwater for u shows multiple benefits for mineral exploration the economy and potable water quality

neogene to quaternary sedimentary basins in the south adriatic central mediterranean foredeeps and lithospheric buckling up to several kilometers deep sedimentary basins of neogene to quaternary age are found in the south adriatic between the apennines and the dinarides albanides they are the apennines foredeep the central adriatic basin and the south adriatic basin two regional seismic lines 260 and 170 km long across the entire system provide hitherto unavailable constraints on the kinematics and dynamics of basin development the apennine foredeep imaged along the lines formed in middle to late pliocene times through a rapid westward tilting of the basin floor a paleobathymetry of few kilometers was created in which allochthonous bodies were emplaced and sediments deposited unaffected by deformation and farther rotations the central and south adriatic basins formed in neogene to quaternary times and are both characterized by strong subsidence in their central parts gradually diminishing toward the edges in the sw and ne depocenters did not shift laterally through time subsidence rates increase through time and subsidence continued also following the end of main shortening episodes in the dinarides albanides the central and south adriatic basins form two crustal scale synclines with subsidence concentrated in their central parts basins geometries and subsidence patterns indicate that the adriatic crust has undergone episodes of buckling since miocene times wavelengths and amplitudes of such folds change along strike corresponding to mechanical changes of the folded medium

formation of segmented normal faults a 3 d perspective the interpretation of fault kinematics from geometric data is an essential step in developing an understanding of the growth of fault systems constraints on fault geometry are however often restricted to 2 d maps or cross sections in this article we consider the extent to which kinematic interpretations of faulting benefit from a 3 d rather than 2 d geometrical perspective concentrating on relay zones and segmented normal fault arrays we suggest that very different interpretations of their evolution arise from the recognition that the propagation directions of faults and fault segments will rarely be contained within the inspection plane of 2 d data a 3 d perspective favours an interpretation in which the segments of a fault array are kinematically interrelated from their initiation individual segments in such systems may link into a single fault surface out of the plane of inspection or may be unconnected in 3 d we argue that this interpretation which conflicts with the often suggested model of incidental overlap of originally isolated faults should be the preferred model for the generation and growth of segmented normal fault arrays

palinspastic restoration and paleogeographic reconstruction of the peri tyrrhenian area during the neogene abstract this paper presents the results of research carried out on the paleogeographic and geodynamic post collisional evolution of the peri tyrrhenian area from the southern alps to sicily during this post collisional evolution a back arc area thrust belt foredeep system developed in which the following tectono sedimentary zones can be distinguished from the external to the internal ones the foreland zone connected to the foredeep through a slope generally controlled by normal faults the foredeep an assymmetric depression with strong subsidence related to the compressional activity of the thrust zone the chain whose outward migration from the late oligocene onward was discontinuus with important stages of crisis partially connected to the mechanical response of different crustal thicknesses existing in the foreland the discontinuous satellite basins developed within the thrust belt the back arc basins developed in the inner part of the chain where the superposition of the extensional tectonics over previous compressional domains causes the fragmentation of the thrust belt leading to its destruction according to this model seven palinspatic maps are discussed regarding the following time intervals late oligocene 25 24 m y burdigalian 22 20 m y langhian 17 16 m y serravallin 15 13 m y tortonian 10 9 m y late messinian 5 5 5 3 m y and early pliocene 5 3 4 6 m y during five of these time intervals significant geodynamic modifications occurred in the whole peri tyrrhenian area leading to paleogeographic changes in any case the geodynamic evolution of the whole area seems clearly controlled by the activity of important bundles of tectonic lines transversal to the chain which in the same time interval in the outermost part of the thrust belt separated areas with different values of shortening and in tthe most internal zones separated segments having different amount of extension these tectonic lines certainly have a crustal significance and have probably acted along previous formed discontinuities