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1.
The central part of the Zagros Fold-Thrust Belt is characterized by a series of right-lateral and left-lateral transverse tear fault systems, some of them being ornamented by salt diapirs of the Late Precambrian–Early Cambrian Hormuz evaporitic series. Many deep-seated extensional faults, mainly along N–S and few along NW–SE and NE–SW, were formed or reactivated during the Late Precambrian–Early Cambrian and generated horsts and grabens. The extensional faults controlled deposition, distribution and thickness of the Hormuz series. Salt walls and diapirs initiated by the Early Paleozoic especially along the extensional faults. Long-term halokinesis gave rise to thin sedimentary cover above the salt diapirs and aggregated considerable volume of salt into the salt stocks. They created weak zones in the sedimentary cover, located approximately above the former and inactive deep-seated extensional faults. The N–S to NNE–SSW direction of tectonic shortening during the Neogene Zagros folding was sub-parallel with the strikes of the salt walls and rows of diapirs. Variations in thickness of the Hormuz series prepared differences in the basal friction on both sides of the Precambrian–Cambrian extensional faults, which facilitated the Zagros deformation front to advance faster wherever the salt layer was thicker. Consequently, a series of tear fault systems developed along the rows of salt diapirs approximately above the Precambrian–Cambrian extensional faults. Therefore, the present surface expressions of the tear fault systems developed within the sedimentary cover during the Zagros orogeny. Although the direction of the Zagros shortening could also potentially reactivate the basement faults as strike-slip structures, subsurface data and majority of the moderate-large earthquakes do not support basement involvement. This suggests that the tear fault systems are detached on top of the Hormuz series from the deep-seated Precambrian–Cambrian extensional faults in the basement.  相似文献   

2.
A discrete element model is used to investigate progressive cover deformation above a steep (70°), basement normal fault. The cover materials are homogenous with frictional material behavior. In the model shown here both normal and reverse faults in the cover accommodate displacement on the underlying basement fault. The earliest faults are curved, reverse faults which propagate upwards from the basement fault tip into the proto hanging wall. These are replaced, progressively towards the footwall, by subvertical to steep normal faults and finally by a normal fault which dips at an angle predicted by Mohr-Coulomb theory. Thus, most early, secondary structures are located in the hanging-wall of the final, through-going, fault. This structural evolution produces an asymmetric, triangular zone of deformation above the basement fault tip which superficially resembles that associated with trishear; however, its progressive development is quite different. Results also emphasize that the occurrence of reverse faults in extensional settings is not diagnostic of inversion.  相似文献   

3.
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.  相似文献   

4.
This study analyzes the structural development of the Gunsan Basin in the central Yellow Sea, based on multi-channel seismic reflection profiles and exploratory well data. The basin comprises three depressions (the western, central, and eastern subbasins) filled with a thick (ca. 6000 m) Cretaceous to Paleogene nonmarine succession. It was initiated in the early Cretaceous due to intracontinental extension caused by oblique subduction of the Izanagi plate under the Eurasian plate and sinistral movement of the Tan-Lu fault. The basin appears to have undergone transtension in the late Cretaceous–Eocene, caused by dextral movement of the Tan-Lu and its branching faults. The transtension was accommodated by oblique intra-basinal normal faults and strike-slip (or oblique-slip) movement of a NE-trending bounding fault in the northern margin of the central subbasin. The entire basin was deformed (NE–SW contraction) in the Oligocene when tectonic inversion occurred, possibly due to the changes in strike-slip motion, from right- to left-lateral, of the Tan-Lu fault. During the early Miocene, extension resumed by reactivation of the pre-existing normal and transpressional faults. A combination of extension, uplift, and erosion resulted in differential preservation of the early Miocene succession. At the end of the early Miocene, extension ceased with mild contraction and then the basin thermally subsided with ensued rise in sea level.  相似文献   

5.
Flow-parallel linear ridge–runnel (R–R) bedforms composed of mainly cohesive sediments have been investigated at an intertidal site located at Hills Flats in the Severn Estuary, UK. It is argued that the sequences of sand–mud laminae in the ridge sediments indicate strongly that R–R are depositional bedforms. Faint R–R topography scoured in the underlying soft bedrock and parallel rows of coarser particle now found at the base of ridges are evidence of secondary vortices that may have provided a catalyst for mud ridge growth. Bed shear stress remains below the erosion threshold for all but the most recent and weak surficial mud deposits which are removed by evorsion [mechanical erosion by turbulent flows that may also carry sand and/or gravel] during Spring tidal flow ca. 60 cm/s. Differences in flow characteristics between ridges and runnel are minor. Corrasion [to erode or be eroded by abrasion] by sparse coarse sediment largely prevents net deposition in the runnels. Over time a slight imbalance between mud deposition and erosion rates allows slow growth of the ridges suggesting that these mudflats may be especially sensitive to slight changes in the local hydrodynamic regime and/or sediment supply.  相似文献   

6.
张性环境中与断裂相关的褶皱类型及特征   总被引：1，自引：0，他引：1  
张性环境下与断裂相关的褶皱作用 (包括纵向褶皱作用和横向褶皱作用 )的研究刚刚起步 ,以往的研究都将后者归因于走滑扭动或挤压反转的结果。但最新研究表明 ,横向褶皱多与张性环境下正断层作用相关的位移变化密切相关 ,也即横向褶皱是应变控制的构造 ,而不是应力控制的构造。根据相关断裂级别 ,横向褶皱级别也分为 5类 :盆地级别 (一级 )的横向褶皱、控坳及控隆横向褶皱、控凹及控凸横向褶皱、控制断鼻的横向褶皱、小尺度孤立横向褶皱 ,并与断裂分级对应。对张性环境下褶皱同时的干涉和先后的叠加 (统称复合作用 )进行了系统研究 ,对复合褶皱样式进行创新与探讨。这一研究不仅有助于伸展区发现新的圈闭类型 ,指导油气勘探 ;而且在于可创新性地在平面构造图上进行断裂生长顺序和组合规律的定性分析 ,同时还可对沉积相分布、沉积厚度变化等进行对应分析。  相似文献   

7.
北部湾盆地北部坳陷构造——沉积特征及其演化   总被引：1，自引：0，他引：1  
在二维和三维地震资料解释基础上,对北部湾盆地北部坳陷地层分布及断裂系统进行了研究,建立了坳陷断裂分布格局及构造样式;结合地层和钻井资料分析了断裂活动期次和特征,揭示古近纪坳陷构造演化经历了三期幕式断陷活动：古新世,初期拉张裂陷阶段,形成狭小的半地堑;始新世早中期,第二期强烈拉张裂陷阶段,形成统一的湖盆,发育两个沉积中心;渐新世,断坳转换期,涠西南低凸起和3号断裂强烈活动,沉积中心迁移至海中凹陷.这为进一步油气勘探工作提供了有价值的参考.  相似文献   

8.
Swath MR1 data from the remnant Colville and active Kermadec arc margins, south of 33°30 S (SW Pacific), record the structural morphology and evolution of the rifted, and now separate portions, of the proto-Colville–Kermadec arc flanking the actively widening southern Havre Trough back-arc basin associated with Pacific-Australian plate convergence. Both the remnant Colville and active Kermadec arc margins comprise opposing, asymmetric, partially basement exposed, segmented ridges. Differences in morphology between the two ridges are, however, observed. The single, near linear, border fault system, with relief of 1000 m, along the western edge of the Kermadec margin is interpreted to be the exposed fault escarpment of a major, west-dipping, detachment fault. In contrast, two major zig-zag border fault systems along the eastern edge of the Colville Ridge, bounding a back-tilted ridge flank terrace, are interpreted as major antithetic faults between the remnant arc and back-arc region. This contrast in structural morphology coincides with, respectively, lesser and greater degrees of both active tectonism and channel-canyon erosion, on the remnant Colville and active Kermadec margins. These differences are interpreted to reflect the progressive trenchward collapse and associated greater rift flank uplift and incisive erosion of the Kermadec foot-wall contrasting with the non-collapse and relatively lesser rift flank uplift and ridge erosion of the Colville hanging-wall. The data provide further constraints on the early evolution of the Havre Trough in particular, and back-arc basins in general.  相似文献   

9.
An extensive carbonate system in the Gulf of Papua (GoP), developed in the late Oligocene–middle Miocene, was buried by huge influx of siliciclastics originated from Papua New Guinea. Major episodes of siliciclastic influx in the carbonate system are related to tectonic activity in the fold and thrust belt during the Oligocene Peninsular Orogeny, late Miocene Central Range Orogeny, and late Pliocene renewed uplift and exhumation of peninsular region. Siliciclastics did not influence the carbonate deposition during the late Oligocene–middle Miocene, since they were accumulated in the Aure Trough, proximal foreland basin protecting the carbonate system. The most significant burial of the carbonate system started during the late Miocene–early Pliocene in the result of the Central Range Orogeny. However, the largest influx was related to the renewed uplift of the Papuan Peninsula during the early late Pliocene. The shelf edge prograded ∼150 km and formed more than 80% of the modern shelf. This high siliciclastic influx was also enhanced by the “mid” Pliocene global warmth period and intensified East Asian monsoons at 3.6–2.9 Ma. Although many publications exist on carbonate–siliciclastic mixing in different depositional environments, this study helps understand the carbonate–siliciclastic interactions in space and time, especially at basinal scale, and during different intervals of the carbonate system burial by siliciclastic sediments.  相似文献   

10.
A Seabeam reconnaissance of the 400 km-long fast-slipping (88 mm yr-1) Heezen transform fault zone and the 55 km-long spreading center that links it to Tharp transform defined and bathymetrically described several types of ridges built by tectonic uplift and volcanic construction. Most prominent is an asymmetric transverse ridge, at which abyssal hills adjacent to the fault zone have been raised 2–3 km above normal rise-flank depths. Topographic and petrologic evidence suggests that this uplift, which has produced a 5400 m scarp from the crest of the ridge to the floor of a 10 km-wide transform valley, is caused by rapid serpentinization of upper mantle which has been exposed to hydrothermal circulation by fault-zone fracturing of an unusually thin crust. Transverse ridges have been thought atypical of fast-slipping transforms. One class of volcanic ridge more common at these sites is the overshot ridge, formed by prolongation of spreading-center rift zones obliquely across the transform. Overshot ridges are well developed at Heezen transform, especially at the eastern end where an eruptive rift zone extending 60 km from the southern tip of the East Pacific Rise has built a transform-parallel ridge that fills the eastern transform valley. Obliteration of fault-zone structure by ridges overshooting from the spreading center intersections means that the topography of the aseismic fracture zones is not just inherited from that of the active transform fault zone. The latter has several en echelon and overlapping fault traces, linked by short oblique spreading axes that generally form pull-apart basins rather than volcanic ridges. Interpretation of the origin and pattern of the fault zone's tectonic and volcanic relief requires refinement of the plate geography and history of this part of the Pacific-Antarctic boundary, using new Seabeam and magnetic traverses to supplement and adjust the existing geophysical data base.  相似文献   

11.
The synsedimentary faults and basin-marginal fans located in the central part of the deep-water area of the early Oligocene Qiongdongnan Basin have been investigated using seismic profiles, boreholes, and well-log data.Through the formations of the characterized paleogeomorphology, such as transverse anticlines, fault ditches,and step-fault belts, the synsedimentary faults are known to have controlled the development position,distribution direction, and extension scales of the basin-marginal fans. For example, at the pitching ends of two adjacent faults, transverse anticlines developed, which controlled the development positions and distributions of the fans. During the early Oligocene, the faults controlled the subsidence center, and fault ditches were formed at the roots of the faults. In the surrounding salient or low salient areas, which were exposed as provenance areas during early Oligocene, the fault ditches acted as the source channels and determined the flow paths of the clastics, where incised valley fills were obviously developed. The fault ditches which developed in the sedimentary basins were able to capture the drainage systems and influenced the distributions of the fans. The large boundary faults and the secondary faults generated two fault terraces and formed step-fault belts. The first fault terrace caused the clastics to be unloaded. As a result, fans were formed at the entrance to the basin. Then, the second fault terrace caused the fans to move forward, with the fans developing in a larger extension scale. The results obtained in this study will potentially be beneficial in the future prospecting activities for reservoirs and coalmeasure source rocks in the basins located in the deep-water areas of the South China Sea.  相似文献   

12.
The North Gabon coastal rift basins consist of a set of 130–150 long-segment asymmetrically tilted half grabens (Interior Basin) and 000–020 short-segment en échelon half grabens (N'Komi Basin) separated by 040–060 major transverse faults. Tectono-sedimentary analysis of field and subsurface data reveals the control exerted by extensional tectonism over continental sedimentation. During Berriasian to early Barremian times, uniform uniaxial 040–060 extension was responsible for the stretching of the brittle upper crust over a 100-km wide domain. During late Barremian–early Aptian times, the main locus of extension stepped westward resulting in severe end-rift uplift and erosion of the failed Interior and N'Komi rift basins. Early Cretaceous coastal rifts in North Gabon display a wide range of styles from oblique rifting (N'Komi Basin), normal rifting (Interior Basin) to transform rifting. The pre-existing Precambrian tectonic fabric exerts a strong control over the mode and over the 100–300 km-scale segmentation of the rifting.  相似文献   

13.
A discrete element model is used to investigate the progressive deformation of a thin basaltic cover overlying a pre-existing, blind, normal fault as it propagates to the surface. The cover materials representing basalt are homogeneous, strong and display elastic-brittle material behaviour. Cover deformation is seen to evolve through a series of distinct stages. Initial displacement on the underlying fault produces a very gentle, monoclinal, flexure. With continued displacement, open fractures develop at the monocline surface and propagate downwards, whilst the deeper fault propagates upwards. Simultaneously, a series of fractures, in the future hanging-wall of the main fault, develop in the upper part of the cover. The monoclinal flexure is then cut by these structures, producing a surficial fault- and fracture-bounded wedge. Finally, a prominent surface fracture and the upward-propagating fault link, cutting the entire cover sequence. This fault is dilatant in the upper c. 100 m of the cover, has a significant surface aperture and forms a prominent fault scarp. Many of the key model results are strikingly similar to those seen in natural settings, and emphasise that the occurrence of dilatant faults, open fractures and cavities/caves in extensional settings is not necessarily restricted to the very shallow section but can extend to several hundred metres depth. Therefore, the results have implications for permeability and fluid flow in such settings. Comparison is also made with a weak cover experiment, using granular materials with no cohesion or tensile strength, similar to the dry sand used in many analogue modelling studies.  相似文献   

14.
The Melinau carbonate platform initiated during the Mid-Eocene on a rotating slice of the Rajang accretionary prism. The differential sedimentary loading enhanced a rotation of the mobile substratum and created an elongated, asymmetrical wedge-top basin. The extensional southern margin of the basin consists of a 2100–2200-m-thick section of Eocene-to-Oligocene carbonates. These thin laterally towards the northern margin of the basin, where a carbonate factory was active on a postulated underlying thrust. Backstepping and dismemberment of the carbonate system started during the latest Oligocene and deep-marine sedimentation became prevalent over the entire region during the Early Miocene.  相似文献   

15.
Investigations of multi-layer current regime, variations in sea level and wave parameters using a bottom-mounted RDCP (Recording Doppler Current Profiler) during 20 December 2006–23 May 2007 were integrated with surveys on changes of shorelines and contours of beach ridges at nearby Harilaid Peninsula (Saaremaa Island). A W-storm with a maximum average wind speed of 23 m s−1 occurred on 14–15 January with an accompanying sea level rise of at least 100 cm and a significant wave height of 3.2 m at the 14 m deep RDCP mooring site. It appeared that in practically tideless Estonian coastal waters, Doppler-based “vertical velocity” measurements reflect mainly site-dependent equilibrium between resuspension and sedimentation. The mooring site, 1.5 km off the Kelba Spit of Harilaid, was located in the accumulation zone, where downward fluxes dominated and fine sand settled. As a result of storms in January and April, the distal part of the accumulative gravel spit advanced by 50 m, whereas a 30–50 m retreat of the shoreline in the western and northern parts occurred at Cape Kiipsaare. The location of the beach ridges shows that the development of the spit occurs through relatively short-period but infrequent storm events, roughly 2–3 times each decade.  相似文献   

16.
Calcite veins and cements occur widely in Carboniferous and Permian reservoirs of the Hongche fault zone, northwestern Junggar Basin in northwest China. The calcites were investigated by fluid inclusion and trace-element analyses, providing an improved understanding of the petroleum migration history. It is indicated that the Hongche fault behaved as a migration pathway before the Early Cretaceous, allowing two oil charges to migrate into the hanging-wall, fault-core and footwall reservoirs across the fault. Since the Late Cretaceous, the Hongche fault has been sealed. As a consequence, meteoric water flowed down only into the hanging-wall and fault-core reservoirs. The meteoric-water incursion is likely an important cause for degradation of reservoir oils. In contrast, the footwall reservoirs received gas charge (the third hydrocarbon event) following the Late Cretaceous. This helps explain the distribution of petroleum across the fault. This study provides an example of how a fault may evolve as pathway and seal over time, and how reservoir diagenetic minerals can provide clues to complex petroleum migration histories.  相似文献   

17.
In recent years, exploration of the Lower Congo Basin in Angola has focused on the Neogene turbidite sand play of the Malembo Formation. Gravity tectonics has played an important role during deposition of the Malembo Formation and has imparted a well-documented structural style to the post-rift sediments. An oceanward transition from thin-skinned extension through mobile salt and eventually to thin-skinned compressional structures characterises the post-rift sediments. There has been little discussion, however, regarding the influence of these structures on the deposition of the Malembo Formation turbidite sands. Block 4 lies at the southern margin of the Lower Congo Basin and is dominated by the thin-skinned extensional structural style. Using a multidisciplinary approach we trace the post-rift structural and stratigraphic evolution of this block to study the structural controls on Neogene turbidite sand deposition.In the Lower Congo Basin the transition from terrestrial rift basin to fully marine passive margin is recorded by late Aptian evaporites of the Loeme Formation. Extension of the overlying post-rift sequences has occurred where the Loeme Formation has been utilised as a detachment surface for extensional faults. Since the late Cretaceous, the passive margin sediments have moved down-slope on the Loeme detachment. This history of gravity-driven extension is recorded in the post-rift sediments of Block 4. Extension commenced in the Albian in the east of the block and migrated westwards with time. In the west, the extension occurred mainly in the Miocene and generated allochthonous fault blocks or “rafts”, separated by deep grabens. The Miocene extension occurred in two main phases with contrasting slip vectors; in the early Miocene the extension vector was to the west, switching to southwest-directed extension in the late Miocene. Early Miocene faults and half-grabens trend north–south whereas late Miocene structures trend northwest–southeast. The contrast in slip vectors between these two phases emphasises the differences in driving mechanisms: the early Miocene faulting was driven by basinward tilting of the passive margin, but gravity loading due to sedimentary progradation is considered the main driver for the late Miocene extension. The geological evolution of the late Miocene grabens is consistent with southwest-directed extension due to southwest progradation of the Congo fan.High-resolution biostratigraphic data identifies the turbidite sands in Block 4 as early Miocene (17.5–15.5 Ma) and late Miocene (10.5–5.5 Ma) in age. Deposition of these sands occurred during the two main phases of gravity-driven extension. Conditions of low sedimentation rates relative to high fault displacement rates were prevalent in the early Miocene. Seafloor depressions were generated in the hangingwalls of the main extensional faults, ultimately leading to capture of the turbidity currents. Lower Miocene turbidite sand bodies therefore trend north–south, parallel to the active faults. Cross-faults and relay ramps created local topographic highs capable of deflecting turbidite flows within the half grabens. Flow-stripping of turbidity currents across these features caused preferential deposition of sands across, and adjacent to, the highs. Turbidite sands deposited in the early part of the late Miocene were influenced by both the old north–south fault trends and by the new northwest–southeast fault trends. By latest Miocene times turbidite channels crosscut the active northwest–southeast-trending faults. These latest Miocene faults had limited potential to capture turbidity currents because the associated hangingwall grabens were rapidly filled as pro-delta sediments of the Congo fan prograded across the area from the northeast.  相似文献   

18.
Heat flow anomalies provide critical information in active tectonic environments. The Gulf of Cadiz and adjacent areas are affected by the plate convergence between Africa and Europe, causing widespread deformation and faulting. Active thrust faults cause lateral movement and advection of heat that produces systematic variations in surface heat flow. In December 2003 new heat flow data were collected during the research vessel Sonne cruise SO175 in the Gulf of Cadiz over two sites of recent focused research activity: (i) the Gulf of Cadiz sedimentary prism and (ii) the Marques de Pombal escarpment. Both features have also been discussed as potential source areas of the Great Lisbon earthquake and tsunami of 1755. Background heat flow at the eastern terminus of the Horseshoe abyssal plain is about 52–59 mW/m2. Over the Gulf of Cadiz prism, heat flow decreases from ∼57 mW/m2 to unusually low values of 45 mW/m2 roughly 120 km eastward. Such low values and the heat flow trend are typical for active thrusting, supporting the idea of an east-dipping thrust fault. Slip rates are 10 ± 5 mm per year, assuming that the fault dips at 2°. A fault dipping at 5°, however, would result into slip rates of 1.5–5 mm per year, suggesting that subduction has largely ceased. Based on seismic data, the Marques de Pombal fault is interpreted as part of an active fault system located ∼100 km westward of Cape San Vincente. Heat flow over the fault is affected by refraction of heat caused by the 1 km high escarpment. Thermal models suggest that the slip rate along the fault must either be small or shear stresses acting on the fault are rather high. With respect to other fault zones, however, it is reasonable to assume that the fault's slip rate is small.  相似文献   

19.
Many simple (univariate, bivariate) and complex (multivariate) statistical techniques are used to investigate trends in biological communities and to test hypotheses about potential relationships between ecosystem components. However, the simple methods that are commonly used (regression and correlation) are prone to Type I error (rejecting a true null hypothesis) when applied repeatedly. Although multivariate methods are preferable for community analysis, their computations are mathematically demanding and the interpretation of their outputs can be challenging. We present simple community analysis (SCA), an intuitive methodology with which to test for trend and correlation at the community-level. We demonstrate SCA using fish survey and phytoplankton count data: the non-parametric test statistic, Kendall's tau, is used to determine the strength of trends in abundance in 65 species of fish sampled during the Irish groundfish survey (maximal length of sampling periods were 1999–2007 in ICES division VIIg and 2002–2007 in divisions VIa, VIIb and VIIj, however catches of numerous species were not recorded prior to 2003) and in 77 genera of phytoplankton sampled at Irish aquaculture sites (1991–2002). The sample distribution of the test statistic (tau is used here, but other measures may be used) is compared to the expected distribution using distributional tests (Kolmogorov–Smirnov) to evaluate the significance of community-level trends. The phytoplankton community has been increasing in abundance on Irish western and southwestern coasts (Kolmogorov–Smirnov test D > 0.5, p < 0.001). Similarly, and in agreement with previously published long-term studies, Lusitanian fish have been increasing on the shelf to the north and west of Ireland (D ≥ 0.35, p < 0.001), while the boreal community has been declining to the south (southeast, D = 0.47, p < 0.001; southwest, D = 0.32, p = 0.03). Although SCA cannot identify causality, the trends in fish communities are as expected given the combined impacts of climate change and fishing: thus, we suggest that these are currently the main drivers of change and the precise mechanisms at play merit further study with long-term data. Biological processes at aquaculture sites should be investigated further as possible mechanisms explaining both the observed positive trends in the phytoplankton community and the restriction of negative trends to Heterosigma and eight dinoflagellate genera. Applied in conjunction with other statistical tools, SCA should aid researchers who aim to describe change in communities and community-level relationships with covariates. SCA is a powerful tool for hypothesis testing at the community-level, which simultaneously produces information at the community member level for more detailed insight, while providing simple summary statistics for managers and policy makers.  相似文献   

20.
The coupled tectonic and depositional history of extensional basins is usually described in terms of stratigraphic sequences linked with the activity of normal faults. This depositional-kinematic interplay is less understood in basins bounded by major extensional detachments or normal fault systems associated with significant exhumation of footwalls. Of particular interest is the link between tectonics and sedimentation during the migration of normal faulting in time and space across the basin. One area where such coupled depositional-kinematic history can be optimally studied is the Late Oligocene - Miocene Sarajevo-Zenica Basin, located in the Dinarides Mountains of Bosnia and Herzegovina. This intra-montane basin recorded Oligocene – Pliocene sedimentation in an endemic and isolated lake environment. We use field kinematic and sedimentological mapping in outcrops correlated with existing local and regional studies to derive a high-resolution evolutionary model of the basin. The novel results demonstrate a close correlation between moments of normal faulting and high-order sedimentological cycles, while the overall extensional basin was filled by a largely uni-directional sediment supply from the neighbouring mountain chain. The migration in time and space of listric NE-dipping normal faults was associated with a gradual shift of the sedimentological environment. Transgressive-regressive cycles reflect sequential displacements on normal faults and their footwall exhumation, defining a new sedimentological model for such basins. This Early - Middle Miocene extension affected the central part of the Dinarides and was associated with the larger opening of the neighbouring Pannonian Basin. The extension was preceded and followed by two phases of contraction. The Oligocene - Early Miocene thrusting took place during the final stages of the Dinarides collision, while the post-Middle Miocene contraction is correlated with the regional indentation of the Adriatic continental unit. This latter phase inverted the extensional basin by reactivating the inherited basal listric detachment.  相似文献   

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