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1.
A two-dimensional numerical modelling that simulate the kinematic and thermal response of the lithosphere to thinning was used for the quantitative reconstruction of the late Neogene to Recent times tectonic and stratigraphic evolution of the North Sicily continental margin (southern Tyrrhenian Sea). The numerical study of the evolution of the North Sicily margin builds on the crustal image and kinematic interpretation of the margin obtained by Pepe et al. [Tectonics 19 (2000) 241] on the basis of seismic data and gravity modelling. Tectonic modeling indicate that different segments of the margin were undergoing different vertical movements, which are mainly expression of the rifting and thinning of the lithosphere occurred during tectonic evolution of the southern Tyrrhenian Sea. A prediction of the pre-rift basement topography and the Moho along the margin converges to a value of 6.5 km for the depth of necking and a temperature-dependent EET (500° isotherm). The model fails to reproduce the morphology of the Solunto High confirming its non-extensional origin. A polyphase evolution is required to reproduce the observed syn- and post-rift stratigraphy. During the first rifting stage (between 9 and 5 Ma), crustal thinning factors reach maximum values of 1.27 in the Cefalù basin. A similar value is predicted for the subcrustal thinning around 60 km NNE of the profile margin. Crustal thinning factors increase during the second rifting stage (from 4 to 2 Ma) and reach values of 2 and up to 3.5 in the Cefalù basin and in the continent–oceanic transition zone, respectively. Similarly, subcrustal lithospheric thinning factors reach values up to 2.5 in the distal sector of the margin. An uplift of more than 100 m is predicted for the North Sicily shelf and surrounding onshore areas during the post-rift stage. The evolution of thermal structure with time is very sensitive to the partial thinning factors describing the evolution of the thinning itself during time. The lithosphere preserved part of its strength during extension. The effective elastic thickness (EET) along the margin through time is 24 km at the onset of rifting and reaches values less to 8 km during the second rifting stage in the northeastern end of the margin.  相似文献   

2.
Tectono-stratigraphic analysis of the East Tanka fault zone (ETFZ), Suez Rift, indicates that the evolution of normal fault segments was an important control on syn-rift depositional patterns and sequence stratigraphy. Sedimentological and stratigraphic analysis of the Nukhul Formation indicates that it was deposited in a narrow (ca 1–2 km), elongate (ca 5 km), fault-bounded, tidally influenced embayment during the low subsidence rift-initiation phase. The Nukhul Formation is composed of transgressive (TST) and highstand (HST) systems tract couplets interpreted as reflecting fault-driven subsidence and the continuous creation of accommodation in the hangingwall to the ETFZ. The overlying Lower Rudeis Formation was deposited during the high subsidence rift-climax phase, and is composed of forced regressive systems tract (FRST) shallow marine sandbodies, and TST to HST offshore mudstones. Activity on the ETFZ led to marked spatial variability in stratal stacking patterns, systems tracts and key stratal surfaces, as footwall uplift, coupled with regressive marine erosion during deposition of FRST sandbodies, led to the removal of intervening TST–HST mudstone-dominated units, and the amalgamation of FRST sandbodies and the stratal surfaces bounding these units in the footwall. This study indicates that the evolution of normal fault segments over relatively short (i.e. <1 km) length-scales has the potential to enhance or suppress a eustatic sea-level signal, leading to marked spatial variations in stratal stacking patterns, systems tracts and key stratal surfaces. Crucially, these variations in sequence stratigraphic evolution may occur within time-equivalent stratal units, thus caution must be exercised when attempting to correlate syn-rift depositional units based solely on stratal stacking patterns. Furthermore, local, tectonically controlled variations in relative sea level can give rise to syn-rift stacking patterns which are counterintuitive in the context of the structural setting and perceived regional subsidence rates.  相似文献   

3.
Subsidence mechanisms that may have controlled the evolution of the eastern Black Sea have been studied and simulated using a numerical model that integrates structural, thermal, isostatic and surface processes in both two- (2-D) and three-dimensions (3-D). The model enables the forward modelling of extensional basin evolution followed by deformation due to subsequent extensional and compressional events. Seismic data show that the eastern Black Sea has evolved via a sequence of interrelated tectonic events that began with early Tertiary rifting followed by several phases of compression, mainly confined to the edges of the basin. A large magnitude (approximately 12 km) of regional subsidence also occurred in the central basin throughout the Tertiary. Models that simulate the magnitude of observed fault controlled extension (β=1.13) do not reproduce the total depth of the basin. Similarly, the modelling of compressional deformation around the edges of the basin does little to enhance subsidence in the central basin. A modelling approach that quantifies lithosphere extension according to the amount of observed crustal thinning and thickening across the basin provides the closest match to overall subsidence. The modelling also shows that deep crustal and mantle–lithosphere processes can significantly influence the rate and magnitude of syn- to post-rift subsidence and shows that such mechanisms may have played an important role in forming the anomalously thin syn-rift and thick Miocene–Quaternary sequences observed in the basin. It is also suggested that extension of a 40–45 km thick pre-rift crust is required to generate the observed magnitude of total subsidence when considering a realistic bathymetry.  相似文献   

4.
This work focuses on quantitative discrimination of fault segment growth and its effect on sedimentation and stratigraphic evolution in the Tanan Depression, the Tamtsag Basin, Mongolia. Integrated seismic data sets and stratigraphic data suggest that normal faults evolve as fault segments grow, link and amalgamate to form a larger fault. Three main stages in the evolution of fault zone are recorded in the syn-rift stratigraphy. This paper applies a method to effectively discriminate the locus of fault segments by ‘three diagrams’ and quantitatively reconstruct process of fault growth by the maximum throw subtraction method. Backstripped to T23 SB event, the F1 fault comprises four hard-linked segments, and the F2 fault is divided into four soft-linked segments (F2-4 and F2-5 segments are shown by hard linkage) at the T23 structural level. The F1 and F2 fault comprise hard-linked segments at the T23-1 structural level when the F1 and the F2 are backstripped to the T22 (133.9 Ma) SB event. The F1 fault is divided into three soft-linked segments (F1-2 and F1-3 segments are shown by hard linkage), and the F2 fault is divided into four isolated fault segments at the T23-1 structural level when the F1 and the F2 is backstripped to the T23 SB event. Incorporation of paleo-fault geometry, isochron thickness map and sedimentary facies suggest that the transfer zone provided accommodation space for sediment discharge and deposition, and the depocentres were formed at the locus of maximum throw along a fault segment during its overall deposition.  相似文献   

5.
The geometry and architecture of a well exposed syn-rift normal fault array in the Suez rift is examined. At pre-rift level, the Nukhul fault consists of a single zone of intense deformation up to 10 m wide, with a significant monocline in the hanging wall and much more limited folding in the footwall. At syn-rift level, the fault zone is characterised by a single discrete fault zone less than 2 m wide, with damage zone faults up to approximately 200 m into the hanging wall, and with no significant monocline developed. The evolution of the fault from a buried structure with associated fault-propagation folding, to a surface-breaking structure with associated surface faulting, has led to enhanced bedding-parallel slip at lower levels that is absent at higher levels. Strain is enhanced at breached relay ramps and bends inherited from pre-existing structures that were reactivated during rifting. Damage zone faults observed within the pre-rift show ramp-flat geometries associated with contrast in competency of the layers cut and commonly contain zones of scaly shale or clay smear. Damage zone faults within the syn-rift are commonly very straight, and may be discrete fault planes with no visible fault rock at the scale of observation, or contain relatively thin and simple zones of scaly shale or gouge. The geometric and architectural evolution of the fault array is interpreted to be the result of (i) the evolution from distributed trishear deformation during upward propagation of buried fault tips to surface faulting after faults breach the surface; (ii) differences in deformation response between lithified pre-rift units that display high competence contrasts during deformation, and unlithified syn-rift units that display low competence contrasts during deformation, and; (iii) the history of segmentation, growth and linkage of the faults that make up the fault array. This has important implications for fluid flow in fault zones.  相似文献   

6.
The controls and development of early-post-rift, deep-water depositional systems are poorly understood due to their commonly deeply-buried nature. As a consequence, in the subsurface there is usually a lack of well penetrations and/or weak seismic imaging. At outcrop, early post-rift strata have commonly been deformed beyond reasonable recognition by later inversion tectonics. In contrast to these systems, the North Viking Graben shows a well-imaged Cretaceous early post-rift package with good well control and little effect from inversion. Therefore, this paper examines the early post-rift, deep-water depositional systems of the North Viking Graben to determine the controls on their stratigraphic position, geometry and evolution, and thus provide an analogue for comparable systems. Greater understanding of such systems will allow for the enhanced prediction of reservoir units in the subsurface and development of new play models since post-rift intervals are generally under-explored.The basin configuration inherited by the Cretaceous early post-rift in the northern North Sea was set up by Permo-Triassic and Late Jurassic rifting. In the North Viking Graben this established considerable along-strike variability, resulting in a northern basin segment surrounded by steep slopes and faulted-bounded structural highs and a southern basin segment margined by slopes with noticeably gentler gradients. Associated with the Cretaceous post-rift is an overall transgressional trend, which drowned local source areas, resulting in prevalent carbonate and hemipelagic mudstone deposition in the basins. In the North Viking Graben, the uplifted Oseberg fault-block provided the sub-aerial clastic source area until it was submerged in the early Upper Cretaceous.The early post-rift infill of the North Viking Graben was divided into four key seismic stratigraphic units (K1, K2, K3 and K4) using an integration of seismic and well data. Inside this stratigraphic framework, the depositional systems within each K-unit were resolved from characteristic seismic facies, amplitude anomalies, relationship with adjacent reflections, and geomorphologies. In the northern basin segment, the early post-rift stratigraphy contains basin-floor fans, a channel complex and a shoreline-like geometry, whereas the southern basin segment is solely characterised by hemipelagic and carbonate deposition. This spatial variability indicates that one of the dominant controls on the development of the early post-rift depositional systems in the North Viking Graben was the inherited syn-rift fault-controlled topography. The steep slopes bounding the northern basin segment aided the delivery of sediment from the sub-aerial Oseberg source area to the graben whereas the submerged, gentle slopes in the southern basin segment were relatively sediment-starved.Long- and short-term changes in relative sea-level also heavily influenced the evolution of the early post-rift basin stratigraphy. Short-term relative sea-level fall allowed basin-floor fan emplacement whereas short-term relative sea-level stand-still favoured deposition of a channel complex. Deposition of the shoreface-like geometry is associated with a short-term relative sea-level rise. This temporal difference in the style and scale of the depositional systems is also interpreted to reflect the gradual denudation and drowning of the Oseberg source area. Regional short-term trangressive and anoxic events in the northern North Sea further influenced the early post-rift strata, resulting in the deposition of stratigraphic units that can be correlated across the North Sea.  相似文献   

7.
Adakitic intrusive rocks of  430–450 Ma were discovered in the North Qilian orogenic belt, the western section of the Central Orogenic System (COS) in China. These adakitic rocks were lower crust melts rather than slab melts as indicated by their crustal Ce/Pb, Nb/U, Ti/Eu, and Nd/Sm ratios and radiogenically enriched (87Sr/86Sr)i of 0.7053–0.7066 and εNd(t) of − 0.9 to − 1.7. While they are all characterized by low Yb (< 1.1 ppm) and Y (< 11.5 ppm) abundances with high Sr/Y (> 65) and (La/Yb)N (> 13.7) ratios, these adakitic rocks are classified into the low-MgO–Ni–Cr and high-MgO–Ni–Cr groups. The low-MgO samples were derived from partial melting of thickened lower crust, whereas the high-MgO samples were melts from delaminated lower crust, which subsequently interacted with mantle peridotite upon ascent. Adakitic rocks from the adjacent North Qinling orogenic belt also originated from thickened lower crust at  430 Ma. In addition, the North Qilian and North Qinling orogenic belts both consist of lithological assemblages varying from subduction-accretionary complexes at south to central arc assemblages, which include adakitic rocks, then to backarc phases at north. Such a sequence reflects northward subduction of the Qilian and Qinling oceans. In these two orogenic belts, the occurrence of adakitic rocks of common origin and ages together with the similarities in tectonic configurations and lithological assemblages are considered to be the evidence for the continuity between eastern Qilian and western Qinling, forming a > 1000 km Early Paleozoic orogenic belt. In such a tectonic configuration, the Qilian and Qinling oceans that subducted from south possibly represent parts of the large “Proto-Tethyan Ocean”. This inference is supported by the coexistence of Early Paleozoic coral and trilobite specimens from Asia, America and Australia in the North Qilian orogenic belt. Post-400 Ma volcanic rocks occur in the North Qinling orogenic belt but are absent in the North Qilian orogenic belt, indicating that these two orogenic belts underwent distinct evolution history after the closure of the Proto-Tethyan Ocean ( 420 Ma).  相似文献   

8.
A quantitative analysis is presented of the scaling properties of faults within the exceptionally well-exposed Kino Sogo Fault Belt (KSFB) from the eastern part of the 200-km-wide Turkana rift, Northern Kenya. The KSFB comprises a series of horsts and grabens within an arcuate 40-km-wide zone that dissects Miocene–Pliocene lavas overlying an earlier asymmetric fault block. The fault belt is 150 km long and is bounded to the north and south by transverse (N50°E and N140°E) fault zones. An unusual feature of the fault system is that it accommodates very low strains (<1%) and since it is no older than 3 Ma, it could be characterised by extension rates and strain rates that are as low as 0.1 mm/yr and 10−16 s−1, respectively. Despite its immaturity, the fault system comprises segmented fault arrays with lengths of up to 40 km, with individual fault segments ranging up to 9 km in length. Fault length distributions subscribe to a negative exponential scaling law, as opposed to the power law scaling typical of other fault systems. The relatively long faults and segments are, however, characterised by maximum throws of no more than 100 m, providing displacement/length ratios that are significantly below those of other fault systems. The under-displaced nature of the fault system is attributed to early stage rapid fault propagation possibly arising from reactivation of earlier underlying basement fabrics/faults or magmatic-related fractures. Combined with the structural control exercised by pre-existing transverse structures, the KSFB demonstrates the strong influence of older structures on rift fault system growth and the relatively rapid development of under-displaced fault geometries at low strains.  相似文献   

9.
The co-seismic deformations produced during the September 27, 2003 Chuya earthquake (Ms = 7.5) that affected the Gorny Altai, Russia, are described and discussed along a 30 km long segment. The co-seismic deformations have manifested themselves both in unconsolidated sediments as R- and R′-shears, extension fractures and contraction structures, and in bedrock as the reactivation of preexisting schistosity zones and individual fractures, as well as development of new ruptures and coarse crushing zones. It has been established that the pattern of earthquake ruptures represents a typical fault zone trending NW–SE with a width reaching 4–5 km and a dextral strike–slip kinematics. The initial stress field that produced the whole structural pattern of co-seismic deformations during the Chuya earthquake, is associated with a transcurrent regime with a NNW–SSE, almost N–S, trending of compressional stress axis (σ1), and a ENE–WSW, almost E–W, trending of tensional stress axis (σ3). The state of stress in the newly-formed fault zone is relatively uniform. The local stress variations are expressed in insignificant deviation of σ1 from N–S to NW–SE or NE–SW, in short-term fluctuations of relative stress values in keeping their spatial orientations, or in a local increase of the plunge angle of the σ1. The geometry of the fault zone associated with the Chuya earthquake has been compared with the mechanical model of fracturing in large continental fault zones with dextral strike–slip kinematics. It is apparent that the observed fracture pattern corresponds to the late disjunctive stage of faulting when the master fault is not fully developed but its segments are already clearly defined. It has been shown that fracturing in widely different rocks follows the common laws of the deformation of solid bodies, even close to the Earth surface, and with high rates of movements.  相似文献   

10.
Qiongdongnan Basin is a Cenozoic rift basin located on the northern passive continental margin of the South China Sea. Due to a lack of geologic observations, its evolution was not clear in the past. However, recently acquired 2-D seismic reflection data provide an opportunity to investigate its tectonic evolution. It shows that the Qiongdongnan Basin comprises a main rift zone which is 50–100 km wide and more than 400 km long. The main rift zone is arcuate in map view and its orientation changes from ENE–WSW in the west to nearly E–W in the east. It can be divided into three major segments. The generally linear fault trace shown by many border faults in map view implies that the eastern and middle segments were controlled by faults reactivated from NE to ENE trending and nearly E–W trending pre-existing fabrics, respectively. The western segment was controlled by a left-lateral strike-slip fault. The fault patterns shown by the central and eastern segments indicate that the extension direction for the opening of the rift basin was dominantly NW–SE. A semi-quantitative analysis of the fault cut-offs identifies three stages of rifting evolution: (1) 40.4–33.9 Ma, sparsely distributed NE-trending faults formed mainly in the western and the central part of the study area; (2) 33.9–28.4 Ma, the main rift zone formed and the area influenced by faulting was extended into the eastern part of the study area and (3) 28.4–20.4 Ma, the subsidence area was further enlarged but mainly extended into the flanking area of the main rift zone. In addition, Estimates of extensional strain along NW–SE-trending seismic profiles, which cross the main rift zone, vary between 15 and 39 km, which are generally comparable to the sinistral displacement on the Red River Fault Zone offshore, implying that this fault zone, in terms of sinistral motion, terminated at a location near the southern end of the Yinggehai Basin. Finally, these observations let us to favour a hybrid model for the opening of the South China Sea and probably the Qiongdongnan Basin.  相似文献   

11.
The Liaohe Group is an important Paleoproterozoic stratigraphic unit in the northeastern part of the North China Craton and is traditionally subdivided into the North and South Liaohe Groups. Associated with both the North and South Liaohe Groups are voluminous Paleoproterozoic granitoid rocks, named the Liaoji granitoids. Different tectonic models, including terrane amalgamation, continent–arc collision and rift closure, have been proposed to interpret the tectonic setting and evolution of the North and South Liaohe Groups and associated Liaoji granitoids. At the centre of the controversy between these models is whether or not the North and South Liaohe Groups developed on the same Archean basement. Nd isotopic geochemistry of the Liaoji granitoids provides important constraints on this controversial issue. The Liaoji granitoids associated with the North and South Liaohe Groups display similar εNd values, restricted to a narrow range from 0 to 2, implying that these granitoid rocks were derived from the same or a similar magma source. Moreover, the Liaoji granitoids associated with the North and South Liaohe Groups have similar Nd model ages (TDM), ranging from 2.4 to 2.6 Ga, suggesting that the protoliths of the Liaoji granitoids associated with both groups may have formed simultaneously, and that the basement rocks underneath the Liaoji granitoids and associated North and South Liaohe Groups belong to the same continental block rather than two different blocks. Combining lithological, structural and geochronological considerations, we interpret the North and South Liaohe Groups as having developed on a single late Archean basement that underwent Paleoproterozoic rifting associated with the intrusion of the Liaoji granitoids and the formation of the Liaohe Group, and closed upon itself in the Paleoproterozoic.  相似文献   

12.
潍北凹陷中新生代层序地层的沉积模式   总被引：2，自引：1，他引：2       下载免费PDF全文
潍北凹陷是受郯庐断裂带直接控制而发育起来的一个小型中新生代富含油气沉积盆地。根据财震反射界面特征，在凹陷孔店组和沙四段（沙河街组四段）内鉴别出6个地震层序界面，进而划分为5个三级层序。在分析初始湖泛面和最大湖泛面的基础上，对层序内体系域和沉积特征进行了划分与分析。盆地沉积演化可划分为开裂期，早期沉降，再沉降，早期萎缩和晚期沉降五个阶段，并对凹陷内两种层地层的沉积模式进行了总结。  相似文献   

13.
Physical models predict that multiphase rifts that experience a change in extension direction between stretching phases will typically develop non-colinear normal fault sets. Furthermore, multiphase rifts will display a greater frequency and range of styles of fault interactions than single-phase rifts. Although these physical models have yielded useful information on the evolution of fault networks in map view, the true 3D geometry of the faults and associated interactions are poorly understood. Here, we use an integrated 3D seismic reflection and borehole dataset to examine a range of fault interactions that occur in a natural multiphase fault network in the northern Horda Platform, northern North Sea. In particular we aim to: i) determine the range of styles of fault interaction that occur between non-colinear faults; ii) examine the typical geometries and throw patterns associated with each of these different styles; and iii) highlight the differences between single-phase and multiphase rift fault networks. Our study focuses on a ca. 350 km2 region around the >60 km long, N–S-striking Tusse Fault, a normal fault system that was active in the Permian–Triassic and again in the Late Jurassic-to-Early Cretaceous. The Tusse Fault is one of a series of large (>1500 m throw) N–S-striking faults forming part of the northern Horda Platform fault network, which includes numerous smaller (2–10 km long), lower throw (<100 m), predominantly NW–SE-striking faults that were only active during the Late Jurassic to Early Cretaceous. We examine how the 2nd-stage NW–SE-striking faults grew, interacted and linked with the N–S-striking Tusse Fault, documenting a range of interaction styles including mechanical and kinematic isolation, abutment, retardation and reactivated relays. Our results demonstrate that: i) isolated, and abutting interactions are the most common fault interaction styles in the northern Horda Platform; ii) pre-existing faults can act as sites of nucleation for 2nd-stage faults or may form mechanical barriers to propagation; iii) the throw distribution on reactivated 1st-stage faults will be modified in a predictable manner if they are intersected or influenced by 2nd-stage faults; iv) sites of fault linkage and relay-breaching associated with the first phase of extension can act as preferential nucleation sites for 2nd-stage faults; and v) the development of fault intersections is a dynamic process, involving the gradual transition from one style to another.  相似文献   

14.
The Lingshan Island in Shandong Province in the eastern North China Craton, well known for the Late Mesozoic multi-scale slide-slump structures is related to paleo-earthquake. Terrigenous clastic rocks, volcanic clastic rocks and volcanic lavas are extensively exposed in the Lingshan Island and its adjacent regions of the Shandong Province, which led to fierce debates on their ages, sedimentary characteristics and tectono-sedimentary evolution. In this contribution, we present the characteristics of the Late Mesozoic stratigraphy in the Lingshan Island. Whole-rock K–Ar dating of dyke at Beilaishi and rhyolites at Laohuzui of the Lingshan Island yielded ages of 159 Ma and \(106\hbox {–}92\hbox { Ma}\) which coincides with the Laiyang Period rifting and the Qingshan Period rifting in the Jiaolai Basin, respectively. On the basis of the analysis to the Late Mesozoic sedimentary environment of ‘flysch’ and ‘molasse’-like formations as well as tectonic stress fields reconstruction, four episodes of the tectono-sedimentary evolution were established in the Lingshan Island and its adjacent regions in the eastern North China Craton. They consist of two episodes of extensional events for the syn-rift, and two episodes of compression events for the inversion of the post-rift. The entire episodes can be summarized as follows: (1) the first syn-rift NW–SE extension in Laiyang Period can be identified by the ‘flysch’ formation (Unit 1) and by emplacement of the NE-trending dyke in the Laiyang Group. This syn-rift episode can be related to the NW–SE post-orogenic extension resulted from the gravity collapse of the thickened lithosphere along the Sulu Orogen. (2) The first post-rift NW–SE inversion, which was caused by the NW-directed subduction of Izanaqi Plate, can be well documented by the ‘X’ type conjugate joints as well as slide slump folds in Unit 1. (3) The second syn-rift NW–SE extension in Qingshan Period is characterized by rhyolite rocks (Unit 2). This syn-rift episode can be considered to be associated with lithospheric delamination of the thickened lithosphere in the eastern North China Craton. And finally, (4) the second post-rift NW–SE inversion which resulted from the subduction of the Pacific Plate under the eastern North China Craton in the NW direction at the end of the Qingshan Period is recorded by ‘molasse’-like formation (Unit 3).  相似文献   

15.
裂陷盆地蕴含丰富的油气资源,盆地不同演化阶段发育独特的地层结构样式及其砂体成因类型,形成各具特色的油气藏系统。近年来湖盆初始裂陷层系不断获得油气勘探突破,使之成为石油工业界重要关注对象,其多级次断裂演化、组合关系、地貌特征及其与水系和沉积响应关系已成为当前地质学领域关注的热点科学问题。蒙古塔南凹陷下白垩统铜钵庙组良好记录了一套初始裂陷沉积序列,丰富的钻井及地震资料使之可作为理想的研究对象。综合利用地震、岩心及测录井资料,在构造—沉积学理论指导下重建了塔南凹陷初始裂陷构造—沉积演化及源—汇响应模式。研究表明,塔南凹陷初始裂陷第一阶段以新生的分割型小洼陷群为特征,与前裂陷阶段“高山深谷”地貌背景联控下形成短距离输送且数量众多的小型扇群;初始裂陷第二阶段伴随控洼断层长度的迅速增加发生软联结,形成连通且宽浅的盆地结构,发育多套低坡降构造转换带（面积大于50 km2）和西北侧缓坡带（延伸约28 km）供给型大套扇三角洲体系,长轴及陡坡方向水系运输距离较短。实例解析结合调研结果表明,先存水系和盆地地貌结构联合控制初始裂陷盆地源—汇系统,进而形成初始裂陷第一阶段盆地满盆富砂（沟通先存水系）或欠补偿（不沟通先存水系）,年轻短程水系主导的孤立小湖盆群则主要发育小规模近源碎屑沉积物;初始裂陷第二阶段源—汇系统则与该时期断裂体系联结方式有关:断裂晚期联结型湖盆主要发育以短程断崖或小型转换带水系为特征,而断裂早期联结型湖盆形成大型构造转换带水系及三角洲体系,其缓坡带长度亦快速增大,盆地整体具有“富砂”特征。本研究为其他裂陷盆地寻找大型优质砂体提供了科学理论依据。  相似文献   

16.
During the Late Palaeozoic and the Mesozoic, the development and evolution of the North West Shelf of Australia have been mostly driven by rifting phases associated with the break-up of Gondwana. These extensional episodes, which culminated in the opening of the Neotethys Ocean during the Permo-Carboniferous and a series of abyssal plains during the Jurassic-Cretaceous, are characterised by different stress regimes and modes of extension, and therefore had distinctive effects on the margin, and particularly on the Northern Carnarvon Basin.Interpretation of 3D and 2D seismic data enables a structural and stratigraphic analysis of the Late Palaeozoic sediments deposited in the proximal part of the Dampier Sub-basin (Mermaid Nose). Based on their seismic characters, stratigraphic relationship, internal patterns, lateral continuity, and architecture, these units are associated here with the Pennsylvanian?–Early Sakmarian glaciogenic Lyons Group and the Sakmarian–Artinskian Callytharra Formation. The former were deposited in a half-graben whose development is associated with the onset of the Neotethys rifting, and the latter is characterised by restricted deposition, inversion of prograding patterns, and uplift.The integration of seismo-stratigraphic characterisation of the Late Palaeozoic sequences and Mesozoic data from one exploration well (Roebuck-1) enables the construction of subsidence curves for the Mermaid Nose and the interpretation of its geohistory.The tectonic subsidence curves show a striking Permo-Carboniferous rifting phase related to the Neotethys rifting and a discrete Late Jurassic–Early Cretaceous event coeval with the opening and the spreading of the Argo Abyssal Plain.This result points out the predominance of the effects of the Permo-Carboniferous Neotethys episode, whereas the extension related to the Argo Abyssal Plain rifting that occurred later and closer to the studied area, had only limited effects on the subsidence of the proximal Dampier Sub-basin. Therefore, it supports a tectonic model with two distinct modes of extension for the Late Palaeozoic (widespread) and the Mesozoic (localised) rifting phases.  相似文献   

17.
Stratigraphic assessment of the “Tierra Caliente Metamorphic Complex” (TCMC) between Arcelia and Teloloapan in southern Mexico, based on photo interpretation of Landsat Thematic Mapper images and field mapping at the 1:100,000 scale, tests different tectonic evolution scenarios that bear directly on the evolution of the southern North American plate margin. The regional geology, emphasizing the stratigraphy of a portion of the TCMC within the area between Arcelia and Teloloapan is presented. Stratigraphic relationships with units in adjacent areas are also described. The base of the stratigraphic section is a chlorite grade metamorphic sequence that includes the Taxco Schist, the Roca Verde Taxco Viejo Formation, and the Almoloya Phyllite Formation. These metamorphic units, as thick as 2.7 km, are covered disconformably by a sedimentary sequence, 2.9 km thick, composed of the Cretaceous marine Pochote, Morelos, and Mexcala Formations, as well as undifferentiated Tertiary continental red beds and volcanic rocks. The geology may be explained as the evolution of Mesozoic volcanic and sedimentary environments developed upon attenuated continental crust. Our results do not support accretion of the Guerrero terrane during Laramide (Late Cretaceous–Paleogene) time.  相似文献   

18.
Displacement rates of normal faults deduced from stratigraphic data are often unreliable. Here we calculate the velocity of motion on a normal fault from the variations in accommodation potential on both sides of the fault within a high‐resolution time‐frame established by biostratigraphy and physical stratigraphy. Our example is the Ornon normal fault bounding the Early Jurassic Bourg‐d'Oisans Basin formed during Tethyan rifting. We show that motion on the fault was discontinuous when examined at high resolution and over a long time interval. During a first interval (Hettangian to Sinemurian Arietites bucklandi zone) a low rate of displacement (=202–423 m Myr?1) coeval with diffused extensional deformation throughout the sedimentary basin is observed. A second interval of localized deformation (Early Sinemurian Caenisites turneri zone) is characterized by higher rates of displacement on the fault (1846 m Myr?1). Our results concur with recent numerical models identifying the main stages of extensional deformation.  相似文献   

19.
Possibilities for the fate of oceanic plateaus at subduction zones range from complete subduction of the plateau beneath the arc to complete plateau–arc accretion and resulting collisional orogenesis. Deep penetration, multi-channel seismic reflection (MCS) data from the northern flank of the Solomon Islands reveal the sequence stratigraphy, structural style, and age of deformation of an accretionary prism formed during late Neogene (5–0 Ma) convergence between the 33-km-thick crust of the Ontong Java oceanic plateau and the 15-km-thick Solomon island arc. Correlation of MCS data with the satellite-derived, free-air gravity field defines the tectonic boundaries and internal structure of the 800-km-long, 140-km-wide accretionary prism. We name this prism the “Malaita accretionary prism” or “MAP” after Malaita, the largest and best-studied island exposure of the accretionary prism in the Solomon Islands. MCS data, gravity data, and stratigraphic correlations to islands and ODP sites on the Ontong Java Plateau (OJP) reveal that the offshore MAP is composed of folded and thrust faulted sedimentary rocks and upper crystalline crust offscraped from the Solomon the subducting Ontong Java Plateau (Pacific plate) and transferred to the Solomon arc. With the exception of an upper, sequence of Quaternary? island-derived terrigenous sediments, the deformed stratigraphy of the MAP is identical to that of the incoming Ontong Java Plateau in the North Solomon trench.We divide the MAP into four distinct, folded and thrust fault-bounded structural domains interpreted to have formed by diachronous, southeast-to-northwest, and highly oblique entry of the Ontong Java Plateau into a former trench now marked by the Kia–Kaipito–Korigole (KKK) left-lateral strike-slip fault zone along the suture between the Solomon arc and the MAP. The structural style within each of the four structural domains consists of a parallel series of three to four fault propagation folds formed by the seaward propagation of thrust faults roughly parallel to sub-horizontal layering in the upper crystalline part of the OJP. Thrust fault offsets, spacing between thrusts, and the amplitude of related fault propagation folds progressively decrease to the west in the youngest zone of active MAP accretion (Choiseul structural domain). Surficial faulting and folding in the most recently deformed, northwestern domain show active accretion of greater than 1 km of sedimentary rock and 6 km, or about 20%, of the upper crystalline part of the OJP. The eastern MAP (Malaita and Ulawa domains) underwent an earlier, similar style of partial plateau accretion. A pre-late Pliocene age of accretion (3.4 Ma) is constrained by an onshore and offshore major angular unconformity separating Pliocene reefal limestone and conglomerate from folded and faulted pelagic limestone of Cretaceous to Miocene age. The lower 80% of the Ontong Java Plateau crust beneath the MAP thrust decollement appears unfaulted and unfolded and is continuous with a southwestward-dipping subducted slab of presumably denser plateau material beneath most of the MAP, and is traceable to depths >200 km in the mantle beneath the Solomon Islands.  相似文献   

20.
Displacement ratio (Dr) is the ratio between salt thickness (Tv) and sub-salt normal fault displacement (D) (Dr = Tv/D), and it is typically used to predict the degree of geometric and kinematic linkage between sub- and supra-salt fault populations, and the overall structural style in salt-influenced extensional settings. However, we currently lack natural examples of how Dr and the underlying geological controls vary, and how these may control the three-dimensional geometry and evolution of salt-influenced normal fault systems. Furthermore, it is currently unknown if kinematic coherence in salt-influenced extensional settings can be maintained over relatively long length-scales (101–103 m) and for relatively long timeframes, and how this may impact the growth and geometry of large-throw (>500 m), salt-influenced normal fault systems. In this paper we use a 3600 km2, high-quality 3D seismic reflection dataset and borehole data from the Stavanger Fault System (SFS), Egersund Basin, eastern North Sea Basin to investigate; (i) how pre-rift salt thickness (Tv) and sub-salt fault throw (T) control the structural style and evolution of a basin-bounding, salt-influenced normal fault system; and (ii) the role salt plays in maintaining kinematic coherence in normal fault systems. We demonstrate that; (i) pre-rift salt distribution (Tv), specifically its presence in the proto-footwall (i.e., when Tv > 0), is the primary control on partitioning of faulting and (forced) folding along the fault system, and the style of linkage (i.e., hard- or soft-linkage) between sub- and supra-salt fault populations; and (ii) sub- and supra-salt fault populations represent brittle elements of a single, geometrically and kinematically coherent structure, the geometry and evolution of which is related to the ductile translation of strain on a scale (up to 8 km) and duration (c. 65 Myr) that believe is significantly greater and longer than previously documented.  相似文献   

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