exploring seismic inversion methodologies for non stationary geological environments a benchmark study between deterministic and geostatistical seismic inversion this paper presents a comparison between subsurface impedance models derived from different deterministic and geostatistical seismic inversion methodologies applied to a challenging synthetic dataset geostatistical seismic inversion methodologies nowadays are common place in both industry and academia contrasting with traditional deterministic seismic inversion methodologies that are becoming less used as part of the geo modelling workflow while the first set of techniques allows the simultaneous inference of the best fit inverse model along with the spatial uncertainty of the subsurface elastic property of interest the second family of inverse methodology has proven results in correctly predicting the subsurface elastic properties of interest with comparatively less computational cost we present herein the results of a benchmark study performed over a realistic three dimensional non stationary synthetic dataset in order to assess the performance and convergence of different deterministic and geostatistical seismic inverse methodologies we also compare and discuss the impact of the inversion parameterisation over the exploration of the model parameter space the results show that the chosen seismic inversion methodology should always be dependent on the type and quantity of the available data both seismic and well log and the complexity of the geological environment versus the assumptions behind each inversion technique the assessment of the model parameter space shows that the initial guess of traditional deterministic seismic inversion methodologies is of high importance since it will determine the location of the best fit inverse solution

strike slip duplexes abstract strike slip fault systems often contain zones of steep imbricate faults geometrically similar to imbricate fans and duplexes in dip slip thrust and normal fault systems they are evident in map view rather than in vertical sections examples of duplexes are cited from both active and ancient systems and from theoretical and physical models duplexes may form at bends on strike slip faults by a process kinematically analogous to the sequential imbrication of ramps on dip slip faults however some may form and many may initiate as non sequential riedel fractures at fault offsets or on straight fault segments this process is more marked than in dip slip systems where primary anisotropy such as bedding exerts more control on fault geometry strike slip duplexes may be shunted along the fault system parallel to the regional slip vector however duplexes or individual horses will usually also move up or down perpendicular to the slip vector because of the unconstrained upper surface to the fault system these factors mean that no section through a strike slip system should be expected to area balance the faults of strike slip duplexes and imbricate fans may root in kinematically necessary low dip faults or may converge downwards and appear in vertical sections as flower structures

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

cenozoic structural deformation and dynamic processes of the bohai bay basin province china abstract cenozoic structures in the bohai bay basin province can be subdivided into eleven extensional systems and three strike slip systems the extensional systems consist of normal faults and transfer faults the normal faults predominantly trend nne and ne and their attitudes vary in different tectonic settings paleogene rifting sub basins were developed in the hanging walls of the normal faults that were most likely growth faults neogene quaternary sequences were deposited in both the rifting sub basins and horsts to form a unified basin province the extensional systems were overprinted by three nne trending right lateral strike slip systems fault zones although the principal displacement zones pdz of the strike slip fault zones are developed only in the basement and lower basin sequences in some cross sections the structural deformation characteristics of the upper basin sequences also indicate that they are basement involved right lateral strike slip fault zones according to the relationships between faults and sedimentary sequences the extensional systems were mainly developed from the middle paleocene to the late oligocene whereas the strike slip systems were mainly developed from the oligocene to the miocene strike slip deformation was intensified as extensional deformation was weakened extensional deformation was derived from horizontal tension induced by upwelling of hot mantle material whereas strike slip deformation was probably related to a regional stress field induced by plate movement

revitalization of a mature oil bearing basin by a paradigm shift in the exploration concept a case history of bohai bay offshore china abstract the bozhong depression in bohai bay was previously ranked as an unfavorable exploration region due to concerns about reservoir trapping integrity and top seal risks in the mid 1900s a few explorationists began to view the petroleum accumulation conditions more positively they argued that rapid neogene subsidence could have generated a new suite of source potential and that recent continued fault movements may have provided the needed conduits for upward hydrocarbon migration they predicted the existence of lacustrine facies that could supply the needed lateral and top seals for the intensively faulted traps these radical thoughts were gradually formulated into a new concept for the neogene targets this paradigm shift in exploration concepts has since 1995 led to the discovery of nine 9 major oil fields with a combined in place reserves more than double those discovered in the previous thirty 30 years some of these neogene reservoirs appear to be at a dynamic balance between hydrocarbon escape and charge it is speculated that the required driving energy for the charge may have come from earthquake activities

analogue modelling of intraplate strike slip tectonics a review and new experimental results abstract intraplate strike slip zones commonly display intricate 3 d geometries with rapid changes in structural style along strike and with depth strike slip deformation typically results in complex vertical and horizontal sections that can be difficult to interpret coherently physical modelling of strike slip fault systems is a powerful and graphic tool to help in providing a unified picture of the evolution of strike slip zones with considerable spatial and temporal detail a large number of experimental studies have investigated different aspects of strike slip tectonics using materials such as dry sand wet clay or silicone the choice of analogue material and experimental design exerts a strong control on the structures that form in the model here we present a review of different experimental setups used to investigate intraplate strike slip tectonics from the classical riedel experiment to more sophisticated setups using brittle and viscous analogue materials we review our current understanding from models of distributed shear transtension transpression pull apart basins formed in releasing stepovers and popups formed in restraining stepovers in addition we present the results of two new experimental series that investigated 1 the effect of crustal weak zones on strike slip fault zone segmentation and 2 strike slip and transpressional reactivation of extensional basins

progressive localisation of strain during the evolution of a normal fault population abstract the evolution of a syn sedimentary normal fault population has been established from the analysis of a high quality 3d seismic reflection survey from the timor sea offshore nw australia growth of the fault population which initiated ca 6 ma ago occurred in three distinct but temporally overlapping stages the initial stage of fault population evolution was characterised by rapid growth of fault length in the first 1 2 ma of extension displacement rates of individual faults were established during this stage and were constant throughout subsequent fault growth the second stage involved amplification of fault displacements on existing fault traces with minimal fault propagation during the third stage shortening of the traces of active faults and high mortality rates for small faults resulted in a net decrease in fault trace length on successively younger horizons this stage was accompanied by a declining extension rate fault throw populations have constant slopes on each syn faulting horizon however an up sequence shallowing of the slope of length and geometric moment populations demonstrates a progressive concentration of strain onto fewer and larger faults through time if extension were to continue beyond the present value of 4 5 this strain localisation might culminate in the formation of a single active through going fault

tectonics of strike slip restraining and releasing bends restraining and releasing bends are common but enigmatic features of strike slip fault systems occurring in all crustal environments and at regional to microscopic scales of observation regional scale restraining bends are sites of mountain building transpressional deformation and basement exhumation whereas releasing bends are sites of topographic subsidence transtensional deformation basin sedimentation and possible volcanism and economic mineralization because restraining and releasing bends often occur as singular self contained domains of complex deformation they are appealing natural laboratories for earth scientists to study fault processes earthquake seismology active faulting and sedimentation fault and fluid flow relationships links between tectonics and topography tectonic and erosional controls on exhumation and tectonic geomorphology this volume addresses the tectonic complexity and diversity of strike slip restraining and releasing bends with 18 contributions divided into four thematic sections 1 a topical review of fault bends and their global distribution 2 bends sedimentary basins and earthquake hazards 3 restraining bends transpressional deformation and basement controls on development 4 releasing bends transtensional deformation and fluid flow

tectonic evolution of the penglai 7 6 structure and its implications for petroleum exploration in a releasing bend of a strike slip fault system tan lu fault zone east china abstract the penglai 7 6 pl7 6 structure is located on the tan lu fault zone a huge fault zone in east asia tectonism of the tan lu fault zone produced complex structural deformation and was an important factor in petroleum accumulation three dimensional seismic data were employed to document the structural geometry and evolutionary process of the pl7 6 structure and implications for petroleum exploration in a releasing bend of a strike slip fault system were discussed systematic analysis of the seismic data indicates that the main fault the bd2 fault of the tan lu fault system slipped right laterally during the cenozoic strike slip movement of the bd2 fault peaked during deposition of e 1 2 k to e 3 d 3 and decreased largely in intensity during e 3 d 1 2 deposition in the neogene and quaternary the bd2 fault was reactivated formation of the bodongnan low uplift is related to the connection between the bodongnan low uplift n and bodongnan low uplift s the bodongnan low uplift n is represented by an anticline produced by strike slip movement of the bd2 fault and the bodongnan low uplift s is represented by the relatively uplifted strata in the vicinity of an extensional fault the bd3 fault the pl7 6 structure developed above a releasing bend formed by the subsequent strike slip movement of the curved bd3 fault orientations of the shallow faults in the pl7 6 structure are not only associated with the lower bd3 fault but also controlled by the basement high unlike traditional releasing bends that are generally disadvantage to petroleum accumulation due to the lower structural elevation in the center the releasing bend in the pl7 6 structure is favorable for petroleum accumulation because of the three reasons 1 adjacent to generative kitchens 2 located on a regional structural high and 3 served by the releasing bend related faults acting as conduits for vertical petroleum migration

fluid evolution in the strange lake granitic pluton canada implications for hfse mobilisation abstract strange lake is a mid proterozoic peralkaline granite pluton quebec labrador canada that underwent extreme enrichment in high field strength elements hfse including the rare earth elements ree the hfse mineralisation is confined to highly altered pegmatites and the most altered parts of the granites implying a genetic association between hydrothermal fluids and hfse enrichment this study uses analyses of fluid inclusions to investigate the hydrothermal evolution of the strange lake pluton and the role of hydrothermal processes in concentrating the hfse to potentially exploitable levels five groups of inclusions were distinguished from earliest to latest these groups are primary aqueous inclusions 25 wt nacl eq associated with melt inclusions group 1 primary aqueous inclusions 13 23 wt nacl eq associated with ch 4 inclusions groups 2a and b primary aqueous inclusions 9 wt nacl eq associated with co 2 inclusions group 3 primary aqueous inclusions 9 wt nacl eq which contain no carbonic component group 4 and finally secondary aqueous inclusions 19 wt nacl eq including inclusions that outline mineral pseudomorphs also with no detectable carbonic component group 5 most of the inclusions except those in group 5 have conspicuous implosion haloes evident as numerous tiny voids this indicates that the inclusions re equilibrated most likely during isobaric cooling fluid evolution commenced with the exsolution of a saline aqueous liquid 25 wt nacl eq and an immiscible ch 4 h 2 gas from the pegmatitic melt at temperatures of 450 500 c and a pressure of 1100 bars during isobaric cooling the gas component of the fluid was gradually oxidised evolving from being ch 4 dominant to a ch 4 fluid with a significant proportion of higher order hydrocarbons due to oxidative coupling of methane induced by the consumption of o 2 through the alteration of arfvedsonite to aegirine 325 360 c and finally to a co 2 dominated fluid at 300 c the apparent salinity of the aqueous fluid decreased from 25 to 4 5 wt nacl eq due to fluid rock interaction the latter also caused precipitation of nahcolite as a result of the reaction of newly formed co 2 with sodium from decomposing minerals formation of pseudomorphs after primary na zirconosilicates and na titanosilicates and replacement of primary ree silicates by bastnasite ce owing to this interaction the carbonic component of the fluid was consumed which together with the consumption of h 2 o to form al k and fe phyllosilicates contributed to an increase in the fluid salinity up to 19 wt nacl eq light rare earth elements lree were remobilised over 10s to 100 s of metres by the high temperature high salinity fluid preserved as group 1 and 2a inclusions whereas heavy rare earth elements hree were remobilised on a much smaller scale by a late low temperature high salinity fluid trapped as inclusion group 5 fluid preserved as inclusion group 3 may have been responsible for remobilisation of zr and ti

mechanisms of petroleum accumulation in the bozhong sub basin bohai bay basin china part 1 origin and occurrence of crude oils the origin of the fourteen major oil fields in the bozhong sub basin bohai bay basin was studied based on the results of rock eval pyrolysis on more than 700 samples and biomarker analysis on 61 source rock samples and 87 oil samples the three possible source rock intervals have different biomarker assemblages and were deposited in different environments the third member of the oligocene dongying formation e3d3 32 8 30 3 ma in age is characterized mainly by high c19 c23 tricyclic terpane 0 75 high c24 tetracyclic terpane c26 tricyclic terpane 2 5 low gammacerane c30 hopane 0 15 and low 4 methyl steranes c29 steranes 0 15 ratios and was deposited in sub oxic to anoxic environments with significant terrigenous organic matter input the first e2s1 35 8 32 8 ma and third e2s3 43 0 38 0 ma members of the eocene shahejie formation have low c19 c23 tricyclic terpane and low c24 tetracyclic terpane c26 tricyclic terpane ratios and were deposited in anoxic environments with minor terrestrial organic matter input but have different abundances of 4 methyl steranes and gammacerane the hydrocarbon generating potential and biomarker associations of these three source rock intervals were controlled by tectonic evolution of the sub basin and climate changes three oil families derived from e2s3 e2s1 and e3d respectively and three types of mixed oils have been identified all large oil fields in the bozhong sub basin display considerable heterogeneities in biomarker compositions and originated from more than one source rock interval which suggests that mixing of oils derived from multiple source rock intervals or multiple generative kitchens and or focusing of oils originated from a large area of a generative kitchen is essential for the formation of large oil fields in the bozhong sub basin e2s3 and e2s1 derived oils experienced relatively long distance lateral migration and accumulated in traps away from the generative kitchen e3d3 derived oils had migrated short distances and accumulated in traps closer to the generative kitchen such a petroleum distribution pattern has important implications for future exploration there is considerable exploration potential for dongying derived oils in the bozhong sub basin and traps close to or within the generative kitchens have better chance to contain oils generated from the dongying formation

cenozoic evolution of the tan lu fault zone east china constraints from seismic data abstract the tan lu fault zone tlfz is a continental scale strike slip fault zone in the east china that contains rich and significant information about the mesozoic cenozoic evolution of eastern asia it experienced a long term and complex superimposed deformation characterized by mesozoic sinistral and cenozoic dextral motions the fault has a well documented mesozoic sinistral displacement history but its cenozoic history is poorly known in this study based on the observations of the interrelationships of fault kinematics fault geometry and concomitant sedimentation the cenozoic evolution of the tlfz is constrained by abundant seismic data from oil fields numerous bends along the cenozoic master fault sensitively record changes in the stress field during strike slip motion taking into account the cenozoic evolution of the bohai bay basin east china the evolutionary history of these strike slip bends is investigated and the results indicate that dextral motion along the tlfz began at about 40 ma furthermore the cenozoic evolutionary history of the tlfz is suggested to include an extensional deformation with a possible weak sinistral shear from 65 to 40 ma from 40 to 0 ma dextral motion occurred due to a change in the subduction direction of the pacific plate relative to the eurasian plate causing the fault to experience dextral shear with a component of extensional deformation dextral motion was most intense from 40 to 25 ma and then the dextral direction may have suddenly changed from a nearly ne sw trend to a nearly n s trend at around 25 ma dextral motion was relatively enhanced again after 12 ma and was particularly strong after 5 ma episodic and ephemeral thrusting deformation might have occurred during the quaternary the cumulative cenozoic dextral displacement of the tlfz is far smaller than its mesozoic sinistral strike slip displacement may be no more than 21 km

neogene volcanism and holocene earthquakes in the tanlu fault zone eastern china abstract in this paper we study the relationship between neogene volcanism and holocene earthquakes in the tanlu fault eastern china we find that fault segments through which neogene and quaternary magma have extruded do not show holocene slip because they are covered by unfaulted basalts in contrast fault branches that are away from the quaternary volcanic centers display quaternary faulting and are responsible for earthquakes as recorded both historically and geomorphologically therefore magma intrusion appears to modify fault activity in two different ways 1 within the faults the cooling magma serves as a cohesion or barrier welding the faults so that they become stronger in resisting slip 2 beneath the faults the upwelling magma promotes slip of faults above the magma body and hence generation of earthquakes physically the first case results from contraction of the cooling magma which causes a relative increase in fault normal stress so that the fault failure resistance is enhanced the second case results from the upward dynamic force and the heat brought in by the magma body both of which cause the effective fault normal stress to decrease so that the fault failure resistance is reduced that could explain why earthquakes occur on faults bypassing the volcanic centers as typified in the yishu fault zone and in the regions where heat flows are relatively high as shown in the bohai bay area

cenozoic faulting of the bohai bay basin and its bearing on the destruction of the eastern north china craton abstract the cenozoic bohai bay basin is located at the center of the eastern block of the north china craton the structural architecture of this basin provides important clues on the deep seated lithosphere thinning of the north china craton the cenozoic regional stress field is characterized by nw oriented extension however the various cenozoic structural patterns of normal faulting and related transverse folding in the bohai bay basin are controlled not only by cenozoic stress field but also by strain field and mesozoic basement fault assemblages in this area regionally the cenozoic tectonic features and the dynamic evolution of the eastern north china craton are dominated by two lithosphere penetrating fault systems including the sinistral tan lu fault system and the dextral lan liao fault system to the west of the lan liao fault system cenozoic extensional tectonics includes nne trending listric normal faults that controlled half grabens however between these two fault systems are wnw trending half grabens which show basement involved faulting in the north and overlapping relations between sedimentary cover and basement in the south to the east of the tan lu fault the north yellow sea basin is a wnw trending fault depression with faulting in the south and overlapping relations in the north these structural features are inherited from the mesozoic tectonic framework of this area whose tectonic characteristics were completely controlled by two opposite strike slipping faults the trans extensional or oblique rifting in the paleogene followed by extensional faulting and subsequent subsidence furthermore the culmination of the decratonization of the north china craton was also related to an eastward jump of cenozoic subduction of the pacific plate and the far field effect of eastward extrusion of cenozoic subduction of the indian plate and was not essentially restricted to the early mesozoic processes therefore the cenozoic especially 25 ma marks the time of cessation of the processes that led to lithosphere thinning and destruction of the eastern block of the north china craton

neogene quaternary postrift tectonic reactivation of the bohai bay basin eastern china bohai bay basin located in eastern china is considered a cenozoic rifted basin the basin is atypical in terms of its neogene quaternary postrift subsidence history in that it experienced intensive tectonic reactivation rather than the relative tectonic quiescence experienced during this stage by most rift basins this neogene quaternary tectonic reactivation arose principally in response to two tectonic events 1 activity on a dense array of shallow faults and 2 accelerated tectonic subsidence that occurred during the postrift stage these two events were neither strictly temporally nor spatially equivalent the dense array of shallow faults form a northwest southeast trending belt in the central part of the basin with displacement induced by the reactivation of older northeast and northwest trending basement faults and an associated substantial component of strike slip displacement occurring after 5 3 ma the intensive reactivation of these faults contributed to the atypically accelerated rate of postrift tectonic subsidence of the basin that commenced ca however this was not the sole cause of this accelerated tectonic subsidence a combination of geological activity deep within the crust led to the buildup of intraplate stresses and this combined with ongoing thermal subsidence acted as an additional contributory factor that drove unusually high rates of subsidence for this basin this episode of accelerated postrift tectonic reactivation resulted in conditions favorable for hydrocarbon accumulation

fault zone development and strain partitioning in an extensional strike slip duplex a case study from the mesozoic atacama fault system northern chile abstract upper crustal strike slip duplexes provide an excellent opportunity to address the fundamental question of fault zone development and strain partitioning in an evolving system detailed field mapping of the mesozoic atacama fault system in the coastal cordillera of northern chile documents the progressive development of second and third order faults forming a duplex at a dilational jog between two overstepping master faults the sinistral strike slip nnw striking jorgillo and bolfin faults these are constituted by a meter wide core of foliated s c ultracataclasite and cataclasite flanked by a damage zone of protocataclasite splay faults and veins lateral separation of markers along master faults is on the order of a few kilometers second order nw striking oblique slip subsidiary fault zones do not show foliated ultracataclasite lateral sinistral separations are in the range of 10 to 200 m with a relatively minor normal dip slip component in turn third order east west striking normal faults exhibit centimetric displacement oblique slip sinistral normal fault zones located at the southern termination of the bolfin fault form a well developed imbricate fan structure they exhibit a relatively simple architecture of extensional and extensional shear fractures bound by low displacement shear fractures kinematic analysis of fault slip data from mesoscopic faults within the duplex area document that the nw striking and the ew striking faults accommodate transtension and extension respectively examination of master and subsidiary faults of the duplex indicates a strong correlation between total displacement and internal fault structure faults started from arrays of en echelon extensional extensional shear fractures that then coalesced into throughgoing strike slip faults further displacement leads to the formation of discrete bands of cataclasite and ultracataclasite that take up a significant part of the total displacement we interpret that the duplex formed by progressive linkage of horsetail like structures at the southern tip of the bolfin fault that joined splay faults coming from the jorgillo and coloso faults the geometry and kinematics of faults is compared with that observed in analog models to gain an insight into the kinematic processes leading to complex strike slip fault zones in the upper crust

hydrocarbon habitat of the offshore bohai basin china the bohai basin is a major continental petroliferous basin located in eastern china of which the offshore part of the basin contains more than one third of the total petroleum resources in the basin although the basin has been explored for nearly 40 years the offshore part of the basin is just reaching a moderately mature stage of exploration and its petroleum geological features are gradually becoming known the subduction of the pacific plate to the eurasia plate resulted in the convective upwelling of the mantle in the bohai area and triggered the development of nne and ne striking extensional faults along the mesozoic structures in the late paleocene causing the formation of the rift basin during the oligocene the depocenters and subsidence centers of the greater bohai basin migrated from west to east and from south to north and finally concentrated in the offshore part of the basin since the oligocene especially during the neogene due to the indentation of the india block to the eurasia plate the right lateral strike slip movement of the tan lu fault was relatively intense in the offshore part of the basin these characteristics led to the differences between the offshore and onshore sectors in sedimentation structural features and petroleum geology during the deposition of the dongying formation the offshore sector became the depocenter and subsidence center of the basin resulting in the deposition of the lower dongying formation mudstone source rocks while these mudstones are immature in the onshore part of the basin in the offshore bohai most major discoveries have been made in the drape anticlines on the rises in the upper tertiary reservoirs while the lower tertiary reservoirs within the half grabens only serve as secondary reservoirs as the neogene depocenter of the basin the offshore part accommodated some fine grained shallow lacustrine clastics of the lower minghuazhen formation serving as important regional seals for the neogene reservoirs a set of shallow faults and a central faulted anticlinal belt in the shallow upper tertiary sequences were formed during the neogene in the offshore sector under the influence of right lateral strike slip faulting of the tan lu fault these shallow faults networked with deep extensional faults serving as hydrocarbon conduits the central faulted anticline belt along the tan lu fault system also provides significant traps

evolutionary characteristics of the sags to the east of tan lu fault zone bohai bay basin china implications for hydrocarbon exploration and regional tectonic evolution abstract some cenozoic half grabens sags have been found to the east of the tan lu fault zone in the bohai bay basin east china the evolutionary history of these sags is consistent with the entire bohai bay basin besides some remarkable characteristics which had not been mentioned in previous studies of the bohai bay basin are presented and they are the keys to understand the regional tectonic evolution among them two characteristics are emphasized 1 the structural and evolutionary features of the sags were markedly changed at about 38 ma 2 the paleogene basin underwent several times of uplifts and denudations during paleogene the first characteristic shows that the normal faulting was the dominant structural deformation before 38 ma and after then the strike slip movement might initiate to influence the basin the second characteristic indicates remarkable reducing of the present day residual basin relative to the original basin and implies the episodic uplifting of the jiaoliao massif besides our estimation on the hydrocarbon exploration potential of these sags shows that part of them can sustain the formation of medium large oilfield independently while part can contribute to the formation of large oilfield

extensional fault arrays in strike slip and transtension abstract sedimentary basins developed under conditions of strike slip or transtension are subject to significant rotational strains yet faults developed in such regimes are commonly explained using simplified models that ignore rotation the heaves of extensional faults developed provide a means of quantifying this rotation for ideal strike slip simple shear the apparent stretch due to fault heaves can be related simply to shear strain at shear strains above 1 0 previously formed extensional faults begin to show inversion as reverse faults becoming fully inverted at 2 0 in transtensional basins the apparent stretch is related in addition to the initial orientation of the faults which may itself be related to the incremental strain in the stellarton basin of nova scotia canada fault heaves and orientations can be measured from subsurface mine plans measurements of these quantities indicate that strain was only mildly transtensional with a small the measurement of fault heaves potentially provides detailed information on strain wherever strike slip or transtensional basins have been explored in detail by seismic or other subsurface methods

3d seismic characterisation of an array of blind normal faults in the levant basin eastern mediterranean the geometry throw distribution and kinematics of an array of blind normal faults were investigated using a high resolution 3d seismic dataset located in the levant basin offshore israel to establish criteria allowing true blind faults to be distinguished from minor synsedimentary faults a detailed analysis of throw distribution on the fault planes shows that the displacement exhibits a crudely concentric pattern about a maximum region located centrally on a fault plane as expected for ideal blind faults however vertical displacement profiles do not exhibit classical linear or triangular profiles but are mostly flat topped or hybrid in type comparison of unrestricted blind faults to those that interacted with a mechanical boundary or another structure suggests that such interactions significantly modify the throw spatial distribution on a fault plane to distinguish small synsedimentary faults from blind faults we use a combination of three criteria to assess whether a fault grew by blind propagation 1 plunging upper tip region and complementary pattern in the throw contours 2 presence of upper tip propagation fold and 3 absence of stratigraphic evidence that the fault interacted with the free surface

growth of normal faults in multilayer sequences a 3d seismic case study from the egersund basin norwegian north sea abstract we investigate the structural style and evolution of a salt influenced extensional fault array in the egersund basin norwegian north sea through analysis of 3d reflection seismic and well data analysis of fault geometry morphology throw distribution and syn kinematic strata reveal an intricate but systematic style of displacement and growth suggesting an evolution of 1 initial syn sedimentary fault growth contemporaneous with salt mobilization initiated during the late triassic 2 cessation of fault activity and burial of the stagnant fault tips and 3 subsequent nucleation of new faults in the cover above contemporaneous salt re mobilization initiated during the late cretaceous with downward propagation and linkage with faults stage 3 was apparently largely controlled by salt mobilization in response to basin inversion as reactivated faults are located where the underlying salt is thick while the non reactivated faults are found where salt is depleted based on the 3d throw analyses we conclude that a combination of basement faulting and salt re mobilization is the driving mechanisms behind fault activation and reactivation even though the sub and supra salt faults are mainly geometrically decoupled through the salt a kinematic coupling must have existed as sub salt faults still affected nucleation and localization of the cover faults

structural records of the late cretaceous cenozoic extension in eastern china and the kinematics of the southern tan lu and qinling fault zone anhui and shaanxi provinces pr china abstract our study of the late cretaceous cenozoic extension in eastern china is a kinematic analysis of faults 1500 striated fault data 175 stress solutions at 90 sites that has permitted us to separate stress fields belonging to six tectonic events a wnw ese extension 1 has affected eastern china from the campanian to the late palaeocene early ypresian under this extension the qinling qlfz and southern tan lu stlfz fault zones have been dextral transtensional fault zones a first transpressional event 2 nne ssw shortening has occurred during the late ypresian lower lutetian the qlfz and the stlfz have been dextral transpressional fault zones a ne sw extension 3 has affected the weihe graben during the palaeogene after a second transpressional event 4 the ne sw extension 5 has been rejuvenated during the late miocene and the qlfz has been a normal fault zone again and the stlfz a sinistral transtensional fault zone synrift subsidence has occurred in the weihe graben the second transpressional event 4 wnw ese shortening has occurred during the late oligocene early miocene during a period of uplifting and exhumation at that time the stlfz and the qlfz have become sinistral transpressional fault zones a period of extension 6 has taken place during the late pliocene quaternary the extensional direction has trended nnw sse during this event the qlfz has been a sinistral transtensional fault zone and the stlfz a dextral transtensional fault zone these results are compared with those previously published in order to evaluate the regional significance of these tectonic events