stratigraphic development of synkinematic deposits in a large growth fault system onshore brunei darussalam kilometre scale synsedimentary faults associated with well preserved sedimentary successions on both hanging wall and footwall sides are rarely seen in outcrop however one such example is found in a middle miocene deltaic sand shale sequence exposed along the jerudong anticline in onshore brunei darussalam integration of detailed outcrop information with regional geophysical subsurface data documents that 1 initiation of the jalan tutong growth fault was related to delta front instability and failure 2 sediment loading under shallow marine conditions maintained syndepositional faulting 3 growth fault abandonment coincided with a significant basinward shift of deposition and subaerial exposure high resolution analysis of facies characteristics stratal expansion and throw development within the studied growth sequence indicates that differential fault movement strongly influenced facies composition sedimentary geometry and bedding characteristics sandstone poor shelf to lower shoreface successions developed during periods of rapidly increasing fault movement whereas sandstone rich amalgamated upper shoreface deposits preferentially formed during intervals of constant or decreasing throw development the data and interpretations presented may help to focus attention on the complex interplay between tectonics and sedimentation associated with the growth and decay of deltaic faults by providing for the first time an outcrop based view on a feature documented in similar scale only by geophysical subsurface data

laboratory testing of an automatic method for determining normal fault geometry at depth abstract a general kinematic method for determining two dimensional normal fault geometries from a large number of hanging wall horizons has been tested on synthetic data and laboratory models the method assumes that the hanging wall deforms by a combination of arbitrarily inclined bulk simple shear and differential compaction it should be applicable to normal faults which do not change shape as deformation proceeds fault geometry the inclination of simple shear and compaction parameters may all be uniquely determined provided that the geometry of the hanging wall stratigraphy is accurately known prior to and after deformation testing the method on synthetic data has shown that unique solutions can be found solutions obtained using large numbers of hanging wall horizons of laboratory modelled faults are encouraging in each case the method was able to predict a fault geometry close to the fault geometry used in the laboratory model hence bulk simple shear appears to be a good approximation of hanging wall deformation the inclination of simple shear appears to be controlled by the underlying fault geometry rather than the amount of extension or the composition of the hanging wall fill in future it is hoped that a general method similar to this one can be applied routinely to depth converted seismic reflection data

3d seismic study of a shale expulsion syncline at the base of the champion delta offshore brunei and its implications for the early structural evolution of large delta systems an example of a late miocene expulsion rollover syncline related to mobile shale is described from 3d seismic data offshore brunei prodelta shales accumulated in the subsiding syncline were altered after deep burial by overpressure increase and hydraulic fracturing consequently seismic facies was modified from a continuous divergent reflection pattern to a low amplitude disrupted to chaotic seismic facies bounded by a high amplitude event that cross cuts original stratification without the resolution provided by 3d data the high amplitude event would be mistaken for early growth faults and the subdued country rock reflections for mobile shale typical features at the base of large deltas this study shows the existence of expulsion rollovers related to mobile shale which have not been described before and demonstrates that not all bright reflections at chaotic coherent facies boundaries are actually fault planes it also suggests that expulsion synclines even during early phases of delta development may be compaction related features rather than ones that drive the shale mass out of the area of progradation

the influence of pre existing structure on the growth of syn sedimentary normal faults in a deltaic setting niger delta abstract three dimensional seismic reflection data from the western niger delta were used to investigate the segmentation and linkage of a syn sedimentary normal fault array and to estimate the influence of a pre existing normal fault on the geometry and growth of younger faults the nucleation growth and linkage of a regional seaward dipping deltaic fault system were analyzed on reflectivity time horizon slices and vertical seismic sections in the deep subsurface a master fault that consists of two segments northwestern nw and southeastern se grew through time into a single fault by lateral tip propagation reaching a final length of about 15 km after attaining this length displacement along the fault system developed non uniformly through time the analysis of the hanging wall sediments of the deep seated master fault shows two different processes of vertical linkage above the nw and se segment the se segment links vertically to several younger faults contemporaneously with displacement accumulation on the master fault in contrast fault linkage above the nw segment occurred only after an interval of master fault inactivity connecting the deep seated structure upwards to a single syn sedimentary normal fault the observed differences in fault development suggest that although multi segment deltaic faults form single fault systems after segment linkage individual pre linkage characteristics can be preserved supporting a possibly diverse upward growth and connection to younger faults in the overburden the geological interpretations presented highlight the influence of large deep rooted structures on the development location and geometry of shallow deltaic faults documenting the influence of an older structural grain on delta tectonics

activity along the osning thrust in central europe during the lateglacial ice sheet and lithosphere interactions abstract the osning thrust is one of the major fault systems in central europe with a length of approximately 115 km it underwent a polyphase tectonic evolution in the mesozoic that ranged from extensional movements in the jurassic to reverse faulting and thrusting during inversion in the late cretaceous a series of complex metre scale faults and related fold structures are developed within the upper pleistocene alluvial aeolian complex of the upper senne 1 km away from the thrust the faults dip towards the north and show offsets in a range of several decimetres growth strata indicate a two fold evolution of the structures the faults began as normal faults and were later transformed into reverse faults which resulted in the formation of small scale inversion structures with a typical harpoon shape glaciotectonics can be ruled out as the driving mechanism for these structures because new optically stimulated luminescence osl ages imply that the sedimentary succession was deposited during the late pleistocene between 29 3 2 9 ka and 13 1 1 5 ka at which time the ice margin was much further to the northeast we believe the inversion structures were caused by movement on the osning thrust due to generation of a forebulge of the late pleistocene weichselian ice sheet this led to normal faulting as a consequence of extension in the forebulge area during glaciation the osl ages for the normal fault related growth strata are in a range of 16 13 ka later reverse movements occurred during deglaciation due to the n s directed compressional stress field in northern germany numerical simulations of the deglaciation seismicity point to seismic events with a thrust mechanism in the study area between 15 5 and 12 3 ka bp although normal faulting is also possible in this time period numerous soft sediment deformation structures imply that movement on the osning thrust caused earthquakes with a significant magnitude in the autumn of 1612 an earthquake took place in this area it is very likely that this event is related to background seismicity on this fault although movement due to the influence of the ongoing glacial rebound in fennoscandia is also possible

origin of transverse folds in an extensional growth fault setting evidence from an extensive seismic volume in the western gulf of mexico abstract growth faults in gravity driven extensional provinces are dominated by coast parallel trends but coast perpendicular transverse trends are far less documented the clemente tomas fault in the inner texas shelf has corrugations that are transverse to the fault and that plunge downdip a large 8500 km2 high quality 3d seismic survey allows a uniquely encompassing perspective into hanging wall deformation above this corrugated fault surface synextensional strata in the hanging wall are folded into alternating transverse ridges and synclines typically spaced 10 km apart forward modelling in dip profiles of an extensional fault having three ramps produces ramp basin rollover pairs that compare with the seismically revealed ridges and synclines as they translated down the undulose fault plane ramp basins and rollovers were juxtaposed along strike forming the hanging wall ridges and synclines observed offshore texas fault surface corrugations correlate broadly with footwall structure we infer that corrugations on the clemente tomas fault formed by evacuation of an allochthonous salt canopy emplaced in the late eocene to early oligocene early salt evacuation oligocene created an undulose topography that influenced incipient clemente tomas fault segments as they merged to form an inherently undulose fault late salt evacuation early miocene further deformed this fault surface

kinematic analysis of faults in a physical model of growth faulting above a viscous salt analogue abstract syn sedimentary faults overlying an extended ductile layer within a sand model provide an analogue for studying some aspects of the geometry and kinematics of basin scale extensional listric faults associated with salt rollers the displacement analysis techniques used to examine displacement variations over fault surfaces within the sand model show that displacement varies in a regular and predictable manner deviations from simple fault displacement patterns are due to transfers of displacement onto adjacent synthetic faults aggregation of the displacements on adjacent synthetic faults produces more regular patterns of displacement distribution and demonstrates the geometric coherence of the aggregated faults rapid upward decreases in displacement on the model faults are due to fault growth during sedimentation elsewhere in the model post sedimentary faulting is associated with very low upward displacement gradients and pre and syn faulting sedimentation are readily distinguished on cross sectional fault traces in three dimensions a non horizontal line separating the pre faulting and syn faulting sequences tracks the lateral extent of a fault through time backstripping of fault displacements by subtracting the fault displacement of a sedimentary horizon from the displacements of underlying horizons gives the displacement distribution on a fault surface at the time of deposition of the backstripped horizon backstripped fault displacement distributions also allow examination of the general fault structure through time backstripping of fault displacements on one of the larger faults within the model and on an associated hanging wall synthetic splay shows that the two structures originated as a relay zone which was breached by lateral propagation of one of the overlapping faults which form the relay zone the backstripping technique allows determination of the geometrical changes during growth of a fault system

fault relays bends and branch lines abstract branch lines between normal faults and their sub parallel splays mapped from 3d seismic reflection data show a range of forms from straight lines to closed loops the different geometries are interpreted as representing stages in the failure of relay zones and in the progressive replacement of fault tip lines with fault branch lines the geometries of these normal fault branch lines are similar to those for thrusts previously inferred from limited two dimensional data the orientation of the axis of a relay and its associated bends relative to a fault slip direction is identified as an important control on the structures developed within the relay neutral restraining and releasing bends can each occur on any fault type normal reverse and strike slip but data bias is a major factor in determining which bend geometry is most often observed with each fault type on normal faults the initial relay zone geometry controls the dominant branch line orientation and the same control is likely on branch lines associated with the other modes of faulting a review of the relay geometries and strains occurring with all three modes of faulting highlights the role of the orientation of the mechanical anisotropy of a bedded sequence relative to the orientations of fault surface and slip directions this relative orientation determines how the relay strain is accommodated and hence the degree of hard linkage and development of branch lines

structural evolution of shale diapirs from reactive rise to mud volcanism 3d seismic data from the baram delta offshore brunei darussalam two areas of shale diapirism in a deltaic setting were examined using 3d seismic data from offshore brunei to determine the origin evolution and geometry of shale diapirs the study areas cover parts of the egret and ampa fields within the baram delta province the ampa diapir consists of a small bulge of the mobile setap shale around which lies a zone of chaotically disrupted country rock reflections at the crest of this chaotic zone vertical cylindrical shale pipes arise that end in a wider head the diapir heads wear halos of high amplitude reflections probably due to the presence of methane gas the egret data show the same features except that the bulge of the source layer is not detected due to low reflectivity and chaotic reflections at the base of the overburden the bulging of the setap shale on the ampa data is interpreted as modified reactive diapirism in response to differential loading the initial reactive diapir shape was modified by lateral or oblique upward migration of fluidized shales into the hanging wall of the fault controlling the reactive diapir this probably occurred as a network of dykes and sills the presence of some preserved bedding is indicated by weak but coherent reflectivity from the area initially defined as chaotic shale the spreading of overpressure and the injection of shale into the overburden is thought to be a late phenomenon possibly late pliocene or early pleistocene and the mobility of the shale is attributed to overpressure increase due to gas generation within the setap shale and maybe the lower part of the overburden gas migration perhaps ahead of the diapir intrusion probably facilitated the mud injection the ampa and egret diapirs formed in two diapiric phases an early reactive diapirism and a later active diapirism but the phases have little in common they are seperated by about 9 million years of inactivity and differ in process and probably differ in degree of overpressure in overpressure generating mechanism and in properties of the diapiric mud

how normal faulting and sedimentation interact to produce listric fault profiles and stratigraphic wedges abstract in a series of scale experiments we generated listric normal faults by extending models composed of colored sand layers deposited at regular time intervals throughout deformation during syntectonic sedimentation progressive bulk extension along a single set of faults caused domino type tilting of fault blocks underlying tilted faults propagated upwards with constant dips into newly sedimented layers hence fault profiles become progressively more listric tilting of the free surface resulted in asymmetrical depressions and in fan shaped deposits stepwise or continuous geometric models of domino tilting and synchronous sedimentation yield the same structural and stratigraphic features as observed in the sand models the continuous geometric model shows that a critical parameter governing fault curvature is the ratio r between rates of bulk strain and sedimentation both types of models reveal that synchronous sedimentation and bulk extension are capable by themselves of generating listric normal faults

hanging wall fault kinematics and footwall collapse in listric growth fault systems we describe the structure of a listric growth fault system from se asia using high resolution 3 d seismic data the fault system shows systematic changes in geometry and kinematics that are sympathetic with along strike changes in the structure of the bounding fault where the position of the bounding fault remained fixed there is an overall landward decrease in the age of the hanging wall growth faults along strike three phases of footwall collapse caused by the active bounding fault stepping back into the footwall block were responsible for the punctuated stepwise landward migration of the rollover hinge and associated hanging wall growth faults during extension the migration of these hanging wall structures is similar to that predicted by simple analogue models with fixed detachment surfaces care should therefore be taken in defining kinematic models in areas where the geometry of the bounding fault is either poorly defined or unknown

the influence of differential sedimentary loading and compaction on the development of a deltaic rollover abstract three dimensional seismic data and wireline logs from the western niger delta were analyzed to reveal the sedimentary and tectonic history of a major deltaic growth fault depocenter comprising a kilometer scale rollover anticline the seismic units of the rollover show a non uniform thickness distribution with their respective maximum near the main bounding growth fault on the landward side of the system this wedge shaped sediment storage architecture ultimately reflects the non uniform creation of accommodation space in the study area that was controlled by 1 the differential compaction of the hanging wall and footwall strata 2 the lateral variation of fault induced tectonic subsidence above the listric master fault and possibly 3 local subsidence related to the subsurface movement of mobile shale reacting to loading and buoyancy a sequential three dimensional decompaction of the interpreted deltaic rollover units allowed to reconstruct and measure the compaction development of the rollover succession through time documenting that sediment compaction contributed per depositional interval to between 25 and 35 of the generation of depositional space subsequently filled by deltaic sediments the incremental decompaction of sedimentary units was further used to quantify the cumulative amount of accommodation space at and around the studied rollover that was created by fault movement shale withdrawal regional tectonic subsidence isostasy and changes in sea level if data on the regional subsidence and eustasy are available the contribution of these basinwide controls to the generation of depositional space can be subtracted from the cumulative accommodation balance which ultimately quantifies the amount of space for sediments to accumulate created by fault movement or shale withdrawal this observation is important in that it implies that background knowledge on subsidence stratigraphic age and sea level changes allows to reconstruct and quantify fault movement in syn tectonic deltaic growth successions and this solely based on hanging wall isopach trends independent of footwall information

early tertiary sinistral transpression and fault reactivation in the western voring basin norwegian sea implications for hydrocarbon exploration and pre breakup deformation in ocean margin basins the nyk high is an approximately northeast trending late cretaceous to early tertiary structural high situated in the western voring basin offshore norway it is defined by a thick sequence of upper cretaceous to lower tertiary sediments that dip toward the southeast and are cut by normal faults with throws up to 1500 m 4921 ft across fault sediment thickness variations and stratigraphic onlap relationships show that these faults were active during campanian to early paleocene extension prior to the separation of norway from greenland ca 55 ma sediments preserved in the hanging walls of these rift related normal faults are deformed by two populations of folds one set is oriented clockwise of the fault strike the other is oriented parallel to the fault strike stratigraphic relationships show that both sets of folds formed subsequent to rifting during the latest paleocene to the earliest eocene we interpret these folds as having developed during minor sinistral transpression which was partitioned between the northeast southwest sinistral strike slip reactivation of the normal faults and the northwest southeast coaxial shortening folding within the fault hanging walls the nyk high is oriented counterclockwise to the inferred line of the continental breakup we speculate that transpression was driven by north northwest forces arising from the differential topography along the incipient plate boundary and the presence of hot buoyant material beneath this elevated axial region such deformation will not necessarily impact significantly on source rock maturity or the distribution of reservoir sands but can give rise to unusual structural trap geometries it is also likely to increase the connectivity of trap bounding faults

late wisconsinan helmeted muskoxen bootherium bombifrons from southwestern alberta canada the first known occurrence of helmeted muskox in the late wisconsinan ca 16 000 11 000 radiocarbon years bp of alberta is recorded and described 14c dating places the specimen at 10 980 80 ra

seismic and strain studies on large laboratory rock samples being stressed to failure abstract large granite 700 700 700 mm and basalt 580 580 915mm samples were cyclicly loaded to failure strain and ultrasonic velocity measurements were made and acoustic emissions recorded during deformation all measurements were correlated in space and time several zones of acoustic emission sources were identified the acoustic patterns of emission activity within these zones varied greatly with increasing stress 1 a initially active then quiet 2 b initially active then quiet and active again before failure and 3 c activity increasing continuously and at accelerating rate toward failure at constant applied stress the seismic character of the acoustic emission signals was quite different in terms of frequency content and amplitude for the different zones the signals emanating from within a particular zone were very reproducible as recorded on a particular transducer but quite different from transducer to transducer the kaiser effect seems to hold up to about one half of the stress of failure i e very few acoustic emissions were detected when the sample was cycled below previously attained stress as long as was less than about one half of the eventual stress at failure as failure was approached the individual acoustic emission events became more energetic and relatively more power was recorded at lower frequencies strain and ultrasonic velocity measurements indicate large variations in dilatancy in the sample similar measurements on much smaller samples are consistent with these results

seismic structure of the north central chilean convergent margin subduction erosion of a paleomagmatic arc we study the erosive convergent margin of north central chile at similar to 31 degrees s by using high resolution bathymetric wide angle refraction and multichannel seismic reflection data to derive a detailed tomographic 2 d velocity depth model in the overriding plate our velocity model shows that the lowermost crustal velocities beneath the upper continental slope are 6 0 6 5km s which are interpreted as the continental basement composed by characteristic metamorphic and igneous rocks of the coastal cordillera beneath the lower and middle continental slope however the presence of a zone of reduced velocities 3 5 5 0km s is interpreted as the outermost fore arc composed of volcanic rocks hydrofractured as a result of frontal and basal erosion at the landward edge of the outermost fore arc the bathymetric and seismic data provide evidence for the presence of a prominent trenchward dipping normal scarp similar to 1km offset which overlies a strong lateral velocity contrast from similar to 5 0 to similar to 6 0km s this pronounced velocity contrast propagates deep into the continental crust and it resembles a major normal listric fault we interpret this seismic discontinuity as the volcanic continental basement contact of the submerged coastal cordillera characterized by a gravitational collapse of the outermost fore arc subduction erosion has most likely caused large scale crustal thinning and long term subsidence of the outermost fore arc

impacts of small scale faults on continental to coastal plain deposition evidence from the realgrunnen subgroup in the goliat field southwest barents sea norway abstract in this study we synthesise sedimentological fault and amplitude versus angle ava analysis and propose that the fruholmen and tubaen formations realgrunnen subgroup are syn kinematic deposits that record a previously undocumented early phase of mesozoic rifting on the troms finnmark fault complex and within the hammerfest basin the realgrunnen subgroup hosts one of two triassic reservoirs currently being produced in the goliat field here the subgroup sits unconformably on top of the storfjorden subgroup carnian snadd formation away from the goliat field which is characterised by a periclinal anticline the realgrunnen subgroup also comprises the lower middle jurassic nordmela and sto formations sedimentological analysis of six exploration wells reveals that the fruholmen formation was deposited in a prodelta to delta plain environment where tide influenced and fluvial dominated distributary channels are represented by clay siltstones and very fine grained sandstones the overlying tubaen formation is characterised by medium to very coarse grained deposits locally conglomeratic and represents a widespread braid plain with localised alluvial fans displacement profiles of faults and along fault thickness variations demonstrate that an immature fault system was active during deposition of the realgrunnen subgroup a series of unconnected fault segments hosted isolated sub basins and erosional catchment areas in their hanging and footwalls respectively an ava attribute map generated from a 10 ms interval of the uppermost part of the subgroup reveals gross sand prone depositional bodies i e individual and amalgamated channels some of which show meandering geometries ox bow lakes and alluvial fans sand bodies frequently show elongate geometries parallel to faults indicative of syn depositional fault related subsidence driving mechanisms responsible for the norian to rhaetian event may relate to contemporaneous rejuvenation of the fennoscandian hinterland development of the novaya zemlya fold and thrust belt and or the early cimmerian tectonic phase in northern europe

a new 3d geological model and interpretation of structural evolution of the world class rio tinto vms deposit iberian pyrite belt spain abstract a new 3d geological model and interpretation of structural evolution of the rio tinto world class vms deposit are presented in this work the rio tinto volcanogenic massive sulfide vms deposit is located in the spanish segment of the iberian pyrite belt and is hosted by felsic porphyritic volcanic rocks and tuffs computer generated 3d modeling of the different orebodies and host rocks has been carried out using data from around 3000 drill core logs allowing us to build 93 cross sections and 6 plants both 50 m spacing this has enabled us to recognize the geometry and relationships between the mineralization and the earliest carboniferous transtensional tectonics through the development of an extensional pull apart basin with two sub basins separated by the nw se trending eduardo fault the sub basins cerro colorado and san dionisio were limited by two e w strike slip faults the northern and southern faults and bounded in the east and west by the nw se trending nerva and western faults respectively the generated pull apart basin was first filled by a basaltic magmatism of mantle origin and later following the deposition of the intermediate complex sedimentary unit by rhyodacitic volcanic rocks of crustal origin the evolution of the subsiding basins caused the development of an e w oriented rollover anticline that affected these filling rocks as a result of a counterclockwise rotation of the stress axes the primitive pull apart basin evolved into a basin affected by e w transtensional sinistral shearing its northern and southern limits were favorable areas for increased hydrothermal fluid flow which gave way to the huge concentration of vms mineralization located near the limits the northern and to a lesser degree the southern extensional faults thus become channel areas for feeding and discharging of the vms and stockwork ores the main mineralizing period was related to this stage subsequently during the variscan transpressional phase the e w extensional faults were reactivated as inverse faults affecting the volcanic sequence of mafic to felsic composition and the intermediate complex sedimentary unit fault propagation folds developed above these faults affecting the massive sulfides the transition series and the culm flysch sediments with buttressing playing a significant role in the geometry of tectonically inverted structures the vms mineralization and cupriferous stockworks were folded and dismembered from the original conduits in the volcanic series and a dextral reactivation of the nw se trending faults also developed finally it should be emphasized that this new 3d geological model is an approach to provide a better insight into the 3d structure of the world class vms rio tinto deposit and could be a key point for further studies providing a new tool to increase knowledge of the vms mineralizations and exploration guidelines elsewhere in the ipb

impacts of data sampling on the interpretation of normal fault propagation and segment linkage abstract throw distance t d and throw depth t z plots are widely used by researchers and industry to examine the growth of normal faults this study uses high quality three dimensional 3d seismic and outcrop information to review the effect of data sampling on the interpretation of normal fault growth the results show that the accuracy of t d and t z data and of resulting fault slip tendency and leakage factor analyses are dependent on the sampling strategy followed by interpreters and field geologists i e on a sampling interval fault length ratio for discrete structures in particular this work demonstrates that significant geometric changes in t d plots occur when a module error ei for the ratio is larger than 6 9 for faults of all scales and growth histories this implies that a minimum number of measurements should be gathered on discrete faults to produce accurate t d and t z plots and that the number of measurements is dependent on fault length with no prior knowledge of fault segmentation a value of 0 05 should be applied when interpreting faults to fulfil the pre requisite of a i

new insights into deformation mechanisms in the gravitationally driven niger delta deep water fold and thrust belt we use two and three dimensional seismic reflection data from the deep water niger delta fold and thrust belt to document evidence for two discrete postfaulting deformation mechanisms an early phase of thrust propagation folding is followed by folding caused by thickness changes within the basal shale detachment unit the later phase of folding is caused by a lateral redistribution of the strata within the basal detachment unit this example of late deformation occurred over a 4 5 m y period as a result of the displacement of approximately 590 km3 370 mi3 of the underlying strata within the detachment unit in another deformation event in the basal detachment unit about 160 km3 100 mi3 moved laterally creating a synform in the overburden and parallel onlap fill indicative of the relatively rapid creation of accommodation space on the basis of seismic reflection data from the delta and a consideration of the volumes and rates of movement of sedimentary rock we conclude that the poorly imaged succession commonly referred to as mobile shale cannot deform solely by ductile mechanisms as interpretations of shale tectonic provinces have commonly suggested but instead by brittle processes that involve thickening by thrust faulting and subseismic accommodation structures processes such as liquefaction where a complete loss of shear strength is observed had a minimal function therefore the term mobile shale in this setting is widely exaggerated an awareness of postfaulting deformation mechanisms will be important for the successful exploration of gravitationally driven fold and thrust belts

connecting seismically active normal faults with quaternary geological structures in a complex extensional environment the colfiorito 1997 case history northern apennines italy 1 the northern apennines of italy are characterized by a complex tertiary tectonic history where superposed compressional and extensional deformation occurred in such regions characterized by low active extensional strain rate the coseismic surface ruptures are rare and often a matter of much debate resulting in a difficult connection between geological faults i e faults which can be mapped at the surface and seismological faults i e faults which actually generate earthquakes the availability of detailed geological mapping and high resolution seismological data for the colfiorito area struck in 1997 by a sequence of six 5 mw 6 normal faulting earthquakes allow us to compare and verify the existence of geometric and kinematic correspondence between the mapped geological quaternary faults and the activated structures in map view the earthquakes distribution reflects the fault pattern mapped at the surface the length of activated and mapped faults is quite similar 7 10 km the coseismic subsided region imaged by interferometric synthetic aperture radar data is located in the hanging wall of the mapped normal faults that bound the quaternary basins in section view there is a geometric connection between mapped normal faults and the aftershock alignments used to image fault geometry at depth comparison of striated fault planes and aftershock focal mechanism solutions show a strong kinematic consistency this study points out that the quaternary tectonosedimentary evolution and the present day geological and geomorphologic setting of the colfiorito area can be interpreted as the result of repeated extensional earthquakes similar to the 1997 events occurring on nw se trending normal faults our data also show that the main shocks of the colfiorito sequence nucleated close to the intersections between the normal faults and the preexisting compressional transpressional structures which in 1997 acted as lateral barriers to rupture propagation and consequently constrained the fault size

overlapping faults intrabasin highs and the growth of normal faults normal fault systems bounding extensional basins are typically adjoined by a series of subbasins separated by intrabasin highs the strata within these basins form syndepositional anticlines and synclines whose axes are transverse to the strike of the main bounding fault one possible explanation for these intrabasin highs is that they result from persistent along strike deficits in fault displacement such deficits are incompatible with scaling relationships observed between fault displacement and length based on large populations of faults we present data from active normal faults within the basin and range province and from inactive normal faults of the newark basin of eastern north america demonstrating a clear correlation between the along strike position of overlapping splay faults and the location of intrabasin highs as well as syndepositional transverse folds summed displacements for all faults within an intrabasin high are comparable to the displacements on faults bounding flanking subbasins o

sequence stratigraphic responses to shoreline perpendicular growth faulting in shallow marine reservoirs of the champion field offshore brunei darussalam south china sea the champion field offshore brunei darussalam comprises a thick middle upper miocene succession of shallow marine sediments associated with major growth fault systems and deposited as part of the paleo baram delta the structural evolution of the champion field has resulted in an unusual situation where growth faults strike perpendicular to the paleoshoreline orientation shoreface parasequences and tidal estuarine complexes are mapped directly from three dimensional 3 d seismic data calibrated from wells the seismic interpretations provide chronostratigraphic correlations that are more robust than some well based markers because the seismic interpretations have better spatial coverage depositional responses to growth faulting are defined by two end member models 1 layer thickening and 2 addition of layers in the hanging wall layer addition makes correlation across faults problematical growth may be accommodated by either or a combination of these processes and areas of layer addition are related to transgressive events in the hanging wall topographic changes thought to be associated with fault movements may fundamentally change shoreline type sand body orientations and petrophysical properties for discrete periods of time these stratigraphic complexities are linked spatiotemporally to accommodation history but cannot be adequately predicted from well data alone

extensional fault systems in sedimentary basins a review of analogue model studies abstract scaled analogue models have provided graphic new insights into the progressive development of extensional fault systems this paper reviews recent results of an on going analogue modelling programme and compares the structural styles in the models with examples of natural extensional fault systems four fundamental model styles scaled to simulate deformation in brittle sedimentary rocks in the upper 10 km of the crust are reviewed extension above a basal detachment which undergoes stretching over a limited are produces an asymmetric rift graben bounded by planar faults and in which the internal deformation is accommodated by rotational domino faults these experimental results are directly comparable to structures found in intracontinental rifts extension above a basal detechment which undergoes extension under the whole model and which has no constraints at the ends produces domino style fault arrays in the pre rift sequence and listric growth faults in the syn rift sequence these results compare with highly extended rift basins and terranes such as the basin and range province usa extension above a simple listric fault produces a characteristic hangingwall roll over and crestal collapse graben system at high values of extension superposed crestal collapse grabens occur and a fan of listric growth faults is developed these structures bear striking similarities to growth faults in progradational delta systems ramp flat listric extensional fault systems using sand mica models produce a characteristic family of structures with an upper roll over crestal collapse system a ramp syncline and reverse fault fold zone and a lower roll over crestal collapse system an example of a ramp flat fault system from the gulf coast usa is presented as a comparison with the analogue model results preliminary results of three dimensional extensional model experiments are presented to illustrate the complexities in such fault systems in all of the experimental models it is found that the geometry of the underlying detachment system exerts fundamental control on structures produced in the hangingwall the analogue models illustrated in this review provide valid geometric and kinematic templates for the progressive evolution of extensional fault systems in sedimentary basins

listric normal faults an illustrated summary movement along listric normal faults is instrumental in formation of several types of structural traps e g rollover anticlines and upthrown fault block closures this type of fault may occur where brittle rocks overlie ductile rocks in an extensional regime the extensional regime may be locally derived within a broader stress regime of another type as evidenced by transtension associated with strike slip movement and arched strata in a compressive setting the flattening of the fault reflects an increase in ductility of the rocks with depth and in some cases deformation of the fault due to compaction or tilting of the upthrown block the dip angle may vary along the strike of the fault in response to changes in throw in cross section a listric fault may consist of relatively short en echelon fault segments this geometry may be particularly characteristic of growth faults sedimentary faults may sole in ductile strata or they may represent the brittle part of a fault flow system fault patterns commonly are characterized by bifurcation some of which may occur near the ends of individual faults comprising a zone although unequivocal recognition of listric normal faults requires unusually extensive outcrop data close subsurface control or high quality seismic data their presence is suggested indirectly by such features as increasing dip either depth toward the controlling fault reverse drag thick progradational sandstone overlying ductile strata and in some cases arcuate fault patterns basins or uplifts listric normal faults form during rifting drifting and evolution of passive continental margins with concomitant basinal development the basement is offset by listric faults as a fundamental element in the development of other types of basins including those which formed during postorogenic extension they also occur as secondary extensional features in an overall compressive stress regime due to plate convergence and during transform or strike slip faulting modified journal abstract