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1.
陆相断陷盆地的构造层序地层分析 总被引：10，自引：3，他引：7
陆相盆地层序地层构型是构造运动、古气候、古湖平面变化与沉积物补给等动力学要素对沉积基准面控制的综合效应。其中,构造运动对盆地层序界面形成与层序内部充填起至关重要的作用。因此,陆相盆地层序地层研究须以构造层序地层为主线,即通过构造对层序形成与演化的控制分析解释层序地层构型,预测其内部充填特征。经研究,断陷盆地构造运动对层序地层的控制主要表现在:(1)断裂活动通过控制基底升降运动直接制约着盆地沉积物堆积的可容纳空间的变化及至层序地层构型;(2)构造转换带或调节带控制盆地主体物源补给方向和沉积体系分布;(3)断裂活动及其塑造的古地貌控制着沉积体系与砂体分布特征。 相似文献
2.
层序充填动力学——层序地层研究的新方向 总被引：11，自引：3，他引：8
层序地层学经过近半个世纪的发展 ,研究领域由当初的被动大陆边缘盆地扩展到了活动大陆边缘盆地、前陆盆地和陆相盆地 ;从研究全盆地的层序地层到研究盆地中某一具体相带的层序地层 ,研究时代也从起初的中新生代拓宽到了古生代。定年技术的发展和同位素等手段的使用 ,使得对层序级别的划分越来越细 ,对层序发育控制因素的研究更加具体 ,冰川、气候、沉积物供应速率等因素对高级别 (三级或三级以上 )层序发育的控制较为明显 ,但对影响层序发育四大因素 (全球海平面变化、构造、气候、沉积物供应 )的动力机制一直未作根本性的探讨 ;大陆地质是地球动力学的信息库 ,沉积盆地是大陆地质过程的信息反馈和载体 ,是壳、幔动力活动的记录和见证 ,层序作为盆地演化的充填块体 ,记载着盆地的成生、发展、演化的信息 ,层序的旋回性是地球运动节律的直接反映。因此 ,以此为研究对象的层序充填动力学是沉积盆地动力学乃至地球动力学研究的基础 ,是层序地层研究的新方向。 相似文献
3.
A RIFTING STORY OF SOUTH CHINA, WITH PARTICULAR REFERENCE TO RODINIA BREAKUP 相似文献
4.
This paper presents examples of various large tidal sandbodies from the Eocene Roda Sandstone in the southern Pyrenees and the Late Pleistocene and Early Holocene in the East China Sea. An attempt is made to summarize the geometric variability of these large tidal sandbodies in relation to the sediment supply and tidal discharge of the depositional system. Transverse sand bars were developed in low-sinuosity, high-gradient channels with high influxes of coarse sediments and water from fluvial systems. Tidal point bars were formed in meandering low-gradient estuarine channel where tidal influence was stronger and sediment was finer than those of the transverse sand bar. A tidal delta complex was built up at the estuary mouth with an abundant sediment supply and an increased tidal discharge. Tidal sand ridges were formed when relict fluvial or deltaic sands were eroded and reworked by strong tidal currents during subsequent sea-level rise.
Since the sediment supply and the tidal discharge of the depositional system were closely related to the eustatic sea-level change and basin subsidence, i.e. the relative sea-level change, special attention will be given to the relationship between geometric variability of tidal sandbodies and the sequence stratigraphic framework in which various sandbodies occurred. Three orders of eustatic sea-level fluctuations can be recognized. The third-order eustatic sea-level cycle, together with basin subsidence, controlled the development of systems tracts and the occurrence of different tidal sandbodies, such as estuary and tidal flat facies during the late stage of a LSW systems tract (type 1 sequence) or a SM systems tract (type 2 sequence); tidal point bar facies, tidal delta facies or tidal sand-ridge facies during a TR systems tract; estuary facies during an early HS systems tract; and fluvial sand bar facies in a late HS systems tract and the early stage of a SM or LSW systems tract. There are also the fourth-order and fifth-order eustatic fluctuations, which are superimposed on the third-order eustatic changes and have important control on the build-up, abandonment and preservation of composite and single tidal sandbodies, respectively.
Since the deposition of tidal sandbodies is very sensitive to eustatic sea-level changes, recognition of various tidal sandbodies is important in sequence stratigraphy analyses of sedimentary basins and in the facies prediction of clastic sediments in basin modelling. 相似文献
5.
Pratul Kumar Saraswati Urbashi Sarkar Santanu Banerjee 《Journal of the Geological Society of India》2012,79(5):476-482
Three successive subspecies of Nummulites burdigalensis evolved from N. solitarius. These include N. burdigalensis keupperi, N. burdigalensis burdigalensis and N. burdigalensis cantabricus. The evolving lineage is traced in a borehole drilled through the Naredi Formation of Kutch. The associated taxa include N. solitarius and N. fraasi in the lower part and Assilina laxispira and A. spinosa in the upper part of the formation. The better stratigraphic resolution achieved by subspecies identification and the lately redefined Ilerdien Stage in the background of Early Eocene carbon isotope excursion marker, lead to constrain the age of Naredi Formation as Early Eocene, ranging from shallow-benthic zones SBZ6 to SBZ11. 相似文献
6.
SHU Liangshu ZHOU Xinmin DENG Ping ZHU Wenbin 《《地质学报》英文版》2007,81(4):573-586
The Late Triassic to Paleogene(T_3-E) basin occupies an area of 143100 km~2,being the sixth area of the whole of SE China;the total area of synchronous granitoid is about 127300 km~2;it provides a key for understanding the tectonic evolution of South China.From a new 1:1500000 geological map of the Mesozoic-Cenozoic basins of SE China,combined with analysis of geometrical and petrological features,some new insights of basin tectonics are obtained.Advances include petrotectonic assemblages, basin classification of geodynamics,geometric features,relations of basin and range.According to basin-forming geodynamicai mechanisms,the Mesozoic-Cenozoic basin of SE China can be divided into three types,namely:1) para-foreland basin formed from Late Triassic to Early Jurassic(T_3-J_1) under compressional conditions;2) rift basins formed during the Middle Jurassic(J_2) under a strongly extensional setting;and 3) a faulted depression formed during Early Cretaceous to Paleogene (K_1-E) under back-arc extension action.From the rock assemblages of the basin,the faulted depression can be subdivided into a volcanic-sedimentary type formed mainly during the Early Cretaceous(K_1) and a red -bed type formed from Late Cretaceous to Paleogene(K_2-E).Statistical data suggest that the area of all para-foreland basins(T_3-J_1) is 15120 km~2,one of rift basins(J_2) occupies 4640 km~2,and all faulted depressions equal to 124330 km~2 including the K_2-E red-bed basins of 37850 km~2.The Early Mesozoic (T_3-J_1) basin and granite were mostly co-generated under a post-collision compression background, while the basins from Middle Jurassic to Paleogene(J_2-E) were mainly constrained by regional extensional tectonics.Three geological and geographical zones were surveyed,namely:1)the Wuyishan separating zone of paleogeography and climate from Middle Jurassic to Tertiary;2)the Middle Jurassic rift zone;and 3)the Ganjiang separating zone of Late Mesozoic volcanism.Three types of basin-granite relationships have been identified,including compressional(a few),strike-slip(a few), and extensional(common).A three-stage geodynamical evolution of the SE-China basin is mooted:an Early Mesozoic basin-granite framework;a transitional Middle Jurassic tectonic regime; intracontinental extension and red-bed faulted depressions since the Late Cretaceous. 相似文献
7.
Stratigraphic patterns and sequence development in tectonically active extensional basins remain poorly documented in comparison with passive‐margin settings. Rift basin fills are generally characterized by coarsening‐upward trends in response to the rapid creation of accommodation by extensional faulting, and the progressive filling of graben during more quiescent periods. The Early Permian Irwin River Coal Measures in the Northern Perth Basin (Western Australia) record a complex stratigraphic arrangement of conglomerate, sandstone, mudstone and coal, and have been attributed to delta plain depositional environments that developed in a cool–temperate climatic setting during syn‐rift activity. Sedimentary analysis of outcrop and core data from the fault‐bounded Irwin Terrace is used to distinguish nine facies associations reflecting deposition in braided rivers, fixed‐anastomosed channel belts, tide‐influenced coastal environments and storm‐affected distal bays. The broader depositional system is interpreted as a morphologically asymmetrical tide‐dominated embayment with a fluvial and wave influence. The stratigraphic architecture of the Irwin River Coal Measures was strongly influenced by the evolving rift basin margin. Fault reactivation of the major basin‐bounding Darling Fault in the early syn‐rift phase caused footwall uplift and the inception of transverse palaeo‐valleys occupied by braided fluvial systems. Fault block subsidence during the subsequent balanced, backstepping and drowning phases resulted in a dominantly retrogradational stacking pattern indicating progressive flooding of marginal‐marine areas and culminating in deposition of distal marine elements. In the active rift basin, it is proposed that preservation of a shallow‐marine syn‐rift sequence was promoted by the geomorphological confinement of the embayed system increasing tidal current acceleration and hampering transgressive ravinement. The proposed sequence model demonstrates that transgressive successions can develop in the early syn‐rift phase in response to footwall uplift and tectonic subsidence. The syn‐rift sequence recording the filling of an embayment on a rift basin margin may be applied in similar tectonic and/or depositional contexts worldwide. 相似文献
8.
The role of tectonics in controlling temporal and spatial variations in sediment provenance during the evolution of extensional basins from initial rifting to continental breakup and passive margin development are not well established. We test the influence of tectonics in a rift basin that has experienced minimal uplift but significant extension throughout its history: the Perth Basin, Western Australia. We use published zircon U–Pb and Hf isotope data from basin inception through to continental drift and complement this with new data from samples deposited synchronously with the continental breakup of eastern Gondwana. Three primary source regions are inferred, namely the Archean Yilgarn Craton to the east, the Paleo- and Mesoproterozoic Albany–Fraser–Wilkes Orogen to the south and east, and the Mesoproterozoic and Ediacaran–Cambrian Pinjarra Orogen underlying the rift basin and comprising the dominant crustal components to the west and southwest. From mid-Paleozoic basin inception to Early Cretaceous breakup of eastern Gondwana, drainage in the Perth Basin was primarily north- to northwest-directed as evidenced by the dominant Mesoproterozoic detrital zircon cargo, paleodrainage patterns and paleocurrent directions. Thus, provenance was primarily parallel to the rift axis and perpendicular to the extension direction, particularly during periods of thermal subsidence. During episodes of mechanical extension, detrital zircon ages are polymodal and consistently dominated by Paleo- and Mesoproterozoic grains derived from the Albany–Fraser–Wilkes Orogen, but with significant Archean and Neoproterozoic inputs from the rift margins. It is inferred that during mechanical extension the rate of subsidence exceeded sediment supply, which generated basin-margin scarps and enhanced direct input from the rift shoulders. Detrital zircon spectra from temporally-equivalent samples at the rift margin and in the rift axis reveal that distinct sedimentary routing operated on the flanks. In summary, sediment provenance in the Perth Basin (and probably other rift basins) is tectonically controlled by: (1) extension direction, (2) episodes of mechanical extension (rift) or thermal subsidence (post-rift), and (3) proximity to rift axis or rift margin. 相似文献
9.
断陷湖盆缓坡带的构造掀斜作用对其地层叠置样式和沉积体系展布具有重要的控制作用。通过基于“源—汇”系统理论的地层正演模拟研究方法,在三级层序地层格架下（以2 Myr为总时长）对断陷盆地缓坡带构造掀斜型层序地层发育样式及其相关地貌演化、沉积物通量变化进行了定量表征。以恒定的绝对湖平面为研究前提,共建立了高/低沉积物供给的背景下4种不同的地层正演模型。两种不同缓坡带掀斜初始位移模型的设定反映了掀斜点和沉积滨线的相对位置,以便于不同掀斜层序样式对比分析。研究表明,掀斜支点位于滨线之上的模型常形成湖侵和正常湖退,而掀斜支点位于滨线之下的模型常形成强制湖退。滨线迁移轨迹和层序叠置样式的不一致性贯穿整个层序发育过程,是沉积物通量及滨线迁移共同作用的结果。该模型中沉积物通量的变化直接响应于源区地貌演变,滨线迁移则受控于新增可容空间和沉积物供给的相互关系。这一系列构造掀斜型层序模型及其相关成因解释对断陷盆地层序地层格架及其叠置样式的精细解剖具有重要的指导意义。该模拟研究对断陷湖盆的高频湖平面变化特征也有较为合理的解释（如海洋同位素3期以来的贝加尔湖）。然而本次正演模拟所设置的初始地貌较为单一,在相同构造、气候条件下和不同沉积物供给背景下所形成地层模型无法涵盖所有缓坡带层序地层类型。由此可见,基于“源—汇”系统思想探讨断陷盆地层序地层多样性的相关模拟工作仍然任重道远。 相似文献
10.
Lake sedimentological and ecological response to hyperthermals: Boltysh impact crater,Ukraine 
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下载免费PDF全文 The Boltysh meteorite impact crater, Ukraine, formed at the Cretaceous–Palaeogene boundary at ca 65·2 Ma. A borehole drilled in the central part of the crater cored a >400 m thick high‐resolution lacustrine succession that covers the Dan‐C2 hyperthermal event associated with a negative carbon isotope excursion. Continuous terrestrial records of past hyperthermals are of limited availability, which makes this record a unique case study of the continental impact of rapid climate warming. This study uses high‐resolution sedimentological core log data together with thin‐section, X‐ray diffraction, microprobe and palynological analyses to: (i) reconstruct lake sedimentological and ecological development across the carbon isotope excursion; and (ii) assess the environmental effect of hyperthermals on terrestrial ecosystems. Based on detailed facies analysis, five gradual stages of lake formation are identified, which show a strong relationship to carbon isotope shifts and associated climatic trends. Initially, sediment supply into the Boltysh lake was controlled by crater morphology. During later lake stages, sediment supply was increasingly controlled by changes in inflow–evaporation ratios which affected seasonal stratification patterns and longer term lake levels. An inferred increase in atmospheric pCO2 related to the carbon isotope excursion, together with increasing mean annual temperatures, was probably responsible for periodic increases in biological activity of photosynthesising organisms and biomass production. These fluctuations in facies and lake settings largely correspond to orbital‐paced moisture availability oscillations. The gradual reduction in sediment supply commencing during early lake formation prior to carbon isotope excursion inception suggest that the Dan‐C2 event did not initiate sedimentary changes, but intensified sedimentary response to orbital controlled climate change. 相似文献
11.
《Sedimentary Geology》2005,173(1-4):233-275
The lacustrine Ermenek Basin evolved as a SE-trending intramontane graben affected by strike–slip deformation, with the initial two lakes merging into one and receiving sediment mainly through fan deltas sourced from the basin's southern margin. The northern margin was a high-relief rocky coast with a wave-dominated shoreline. The Early Miocene lacustrine sedimentation was terminated by a late Burdigalian marine invasion that drowned the basin and its surroundings. The lacustrine basin-fill succession is up to 300 m thick and best exposed along the southern margin, where it consists of four sequences bounded by surfaces of forced regression. The offshore architecture of each sequence shows a thin lowstand tract of shoreface sandstones overlain by a thick transgressive systems tract of mudstones interbedded with sandy tempestites and delta-derived turbidites, which form a set of coarsening-upward parasequences representing minor normal regressions. The corresponding nearshore sequence architecture includes a thick lowstand tract of alluvial-fan deposits overlain by either a well-developed transgressive systems tract (backstepping parasequence set or single fan-deltaic parasequence) and poorly preserved highstand tract; or a thin transgressive tract (commonly limited to flooding surface) and a well-developed highstand tract (thick fan-deltaic parasequence). The sequences are poorly recognizable along the northern margin, where steep shoreline trajectory rendered the nearshore system little responsive to lake-level changes. The resolution of local stratigraphic record thus depends strongly upon coastal morphology and the character of the depositional systems involved.The sequential organization of the basin-fill succession reflects syndepositional tectonics and climate fluctuations, whereas the lateral variation in sequence architecture is due to the localized sediment supply (deltaic vs. nondeltaic shoreline), varied coastal topography and differential subsidence. The study points to important differences in the sequence stratigraphy of lacustrine and marine basins, related to the controlling factors. A crucial role in lacustrine basin is played by climate, which controls both the lake water volume and the catchment sediment yield. Consequently, the effects of tectonics and the dynamics of changes in accommodation and sediment supply in a lacustrine basin are different than in marine basins. 相似文献
12.
Sebastian Hinsken Kamil Ustaszewski Andreas Wetzel 《International Journal of Earth Sciences》2007,96(6):979-1002
Eocene to Early Oligocene syn-rift deposits of the southern Upper Rhine Graben (URG) accumulated in restricted environments.
Sedimentation was controlled by local clastic supply from the graben flanks, as well as by strong intra-basinal variations
in accommodation space due to differential tectonic subsidence, that in turn led to pronounced lateral variations in depositional
environment. Three large-scale cycles of intensified evaporite sedimentation were interrupted by temporary changes towards
brackish or freshwater conditions. They form three major base level cycles that can be traced throughout the basin, each of
them representing a stratigraphic sub-unit. A relatively constant amount of horizontal extension (ΔL) in the range of 4–5 km has been estimated for the URG from numerous cross-sections. The width of the rift (L
f
), however, varies between 35 and more than 60 km, resulting in a variable crustal stretching factor between the bounding
masterfaults. Apart from block tilting, tectonic subsidence was, therefore, largely controlled by changes in the initial rift
width (L
0). The along-strike variations of the graben width are responsible for the development of a deep, trough-like evaporite basin
(Potash Basin) in the narrowest part of the southern URG, adjacent to shallow areas in the wider parts of the rift such as
the Colmar Swell in the north and the Rhine Bresse Transfer Zone that delimits the URG to the south. Under a constant amount
of extension, the along-strike variation in rift width is the principal factor controlling depo-centre development in extensional
basins. 相似文献
13.
During the Cenozoic numerous shallow epicontinental evaporite basins formed due to tectonic movements in the Northern Province of the Central Iran Tectonic Zone (the Great Kavir Basin). During the Miocene, due to sea‐level fluctuations, thick sequences of evaporites and carbonates accumulated in these basins that subsequently were overlain by continental red beds. Development of halite evaporites with substantial thickness in this area implies inflow of seawater along the narrow continental rift axis. The early ocean basin development was initiated in Early Eocene time and continued up to the Middle Miocene in the isolated failed rift arms. Competition between marine and non‐marine environments, at the edge of the encroaching sea, produced several sequences of both abrupt and gradual transition from continental wadi sediments to marginal marine evaporites in the studied area. These evaporites show well‐preserved textures indicative of relatively shallow‐brine pools. The high Br content of these evaporites indicates marine‐derived parent brines that were under the sporadic influence of freshening by meteoric water or replenishing seawater. However, the association of hopper and cornet textures denotes stratified brine that filled a relatively large pool and prevented rapid variations in the Br profile. Unstable basin conditions that triggered modification of parent brine chemistry prevailed in this basin and caused variable distribution patterns for different elements in the chloride units. The presence of sylvite and the absence of Mg‐sulphate/chlorides in the paragenetic sequence indicate SO4−depleted parent brine in the studied sequence. Petrographic examinations along with geochemical analyses on these potash‐bearing halites reveal parental brines which were a mixture of seawater and CaCl2‐rich brines. The source of CaCl2‐rich brines is ascribed to the presence of local rift systems in the Great Kavir Basin up to the end of the Early Miocene. Copyright © 2007 John Wiley & Sons, Ltd. 相似文献
14.
裂谷作用对层序地层充填样式的控制——以西非裂谷系Termit盆地下白垩统为例 总被引：1，自引：0，他引：1
Termit盆地位于尼日尔东南部,属于西非裂谷系的北延部分,是发育于前寒武系—侏罗系基底之上的中、新生代裂谷盆地。该盆地早白垩世—古近纪经历了"裂谷—坳陷—裂谷"的构造演化过程及"陆相—海相—陆相"的沉积演化过程,表现为晚白垩世大规模海侵、早白垩世和古近纪两期裂谷叠置的特点。基于构造作用影响裂谷盆地层序发育的观点,分析了Termit盆地下白垩统裂谷阶段内的层序地层充填样式。根据裂谷作用的强弱,将早白垩世裂谷阶段划分为裂谷初始期、裂谷深陷期及裂谷萎缩期3个阶段。裂谷初始期层序断裂活动弱,构造沉降小,长轴物源体系较为发育,陡坡带为加积至退积型河流或三角洲沉积,缓坡带发育加积型河流或三角洲体系。裂谷深陷期层序断裂活动强烈,构造沉降大,陡坡带形成退积型水下扇或滑塌扇沉积,缓坡带发育退积型三角洲体系,盆地中心为泥岩充填。裂谷萎缩期层序断裂活动减弱并趋于停止,陡坡带为进积型扇三角洲沉积,缓坡带发育进积型三角洲体系。研究表明:裂谷作用对层序地层充填样式具有明显的控制作用,以构造作用为主线的裂谷盆地层序地层分析方法,能有效预测沉积体系和储层分布。 相似文献
15.
The Piceance Creek basin formed as a continental foreland basin ca 53 to 48 Ma in the early to middle Eocene. On a global basis, the basin contains one of the richest oil shale resources known, where the profundal oil shale deposits, kerogen‐rich mudstones (clay and carbonate), exist over most of the basin. Despite its economic importance, the evolution of the Piceance Creek basin is still somewhat unclear. Based on facies association analysis, depositional trends, and gamma ray and Fischer assay data, six evolutionary lake stages are recognized: (i) fresh lake; (ii) transitional lake; (iii) highly fluctuating lake; (iv) rising lake; (v) high lake; and (vi) closing lake. Lake stages are composed of depositional units and characterize large‐scale changes in sedimentological patterns, depositional trends and fluctuations in the oil shale richness related to changes in climate and tectonics. Lake stage evolution is also consistent with the global Eocene climate trend. Stage 1 formed prior to the Eocene climate optimum. At the beginning of the Eocene climate optimum, a saline‐restricted lake formed (Stage 2) and evolved into the highly fluctuating lake (Stage 3) indicating rapid climate changes during the peak of the Eocene climate optimum. This stage was followed by the rising and high lakes (Stages 4 and 5) after the climate optimum and during a change to a more humid climate. The closing of the lake (Stage 6) was caused by increased sand input from the north, indicating the influence of both tectonics and climate. Based on depositional trends and climate evolution, it is suggested that, during the arid climate, laterally heterogeneous highly cyclic depositional units dominate, whereas, during the humid climate, depositional units form laterally continuous sediments that can be traced over long distances. 相似文献
16.
In large parts of the Kachchh Basin, a Mesozoic rift basin situated in western India, the Oxfordian succession is characterized by strong condensation and several depositional gaps. The top layer of the Early to Middle Oxfordian Dhosa Oolite member, for which the term ‘Dhosa Conglomerate Bed’ is proposed, is an excellent marker horizon. Despite being mostly less than 1 m thick, this unit can be followed for more than 100 km throughout the Kachchh Mainland. A detailed sedimentological analysis has led to a complex model for its formation. Signs of subaerial weathering, including palaeokarst features, suggest at least two phases of emersion of the area. Metre‐sized concretionary slabs floating in a fine‐grained matrix, together with signs of synsedimentary tectonics, point to a highly active fault system causing recurrent earthquakes in the basin. The model takes into account information from outcrops outside the Kachchh Mainland and thereby considerably refines the current understanding of the basin history during the Late Jurassic. Large fault systems and possibly the so‐called Median High uplift separated the basin into several sub‐basins. The main reason for condensation in the Oxfordian succession is an inversion that affected large parts of the basin by cutting them off from the sediment supply. The Dhosa Conglomerate Bed is an excellent example, demonstrating the potential of condensed units in reconstructing depositional environments and events that took place during phases of non‐deposition. Although condensed sequences occur frequently throughout the sedimentary record, they are particularly common around the Callovian to Oxfordian transition. A series of models has been proposed to explain these almost worldwide occurrences, ranging from eustatic sea‐level highstands to glacial phases connected with regressions. The succession of the Kachchh Basin shows almost stable conditions across this boundary with only a slight fall in relative sea‐level, reaching its minimum not before the late Early Oxfordian. 相似文献
17.
18.
塔里木盆地寒武系层序地层格架 总被引：16，自引：0，他引：16
通过露头、钻测井及地震层序地层特征综合分析,建立了塔里木盆地寒武系三级层序地层格架,将寒武系划分出6个可全盆地追踪与对比的三级层序。结合反映全球海平面相对变化的全岩碳同位素旋回与反映沉积古水深相对变化的沉积旋回的对比分析,可将塔里木盆地寒武系三级层序分为主要受全球海平面变化控制形成的全球海平面层序(层序CSQ2、CSQ4、CSQ5、CSQ6)及主要受地区性构造沉降作用控制形成的构造层序(层序CSQ1、CSQ3)2类。塔北轮南地区寒武系台地边缘总体呈现由早寒武世的缓坡向中—晚寒武世的镶边台地的演变以及由西向东的进积叠置型式,推测主要与寒武纪全球海平面总体微弱下降及塔里木盆地基底沉降速率总体稳定且较小有关。 相似文献
19.
ABSTRACT A three‐dimensional numerical model of sediment transport and deposition in coarse‐grained deltas is used to investigate the controls on depositional sequence variability in marine half‐graben extensional basins subject to eustatic sea‐level change. Using rates of sea‐level change, sediment supply and fault slip reported from active rift basins, the evolution of deltas located in three contrasting structural settings is documented: (1) footwall‐sourced deltas in high‐subsidence locations near the centre of a fault segment; (2) deltas fed by large drainage catchments at fault tips; and (3) deltas sourced from drainage catchments on the hangingwall dip slope. Differences in the three‐dimensional form and internal stratigraphy of the deltas result from variations in tilting of the hangingwall and the impact of border fault slip rates on accommodation development. Because subsidence rates near the centre of fault segments are greater than all but the fastest eustatic falls, footwall‐sourced deltas lack sequence boundaries and are characterized by stacked highstand systems tracts. High subsidence and steep bathymetry adjacent to the fault result in limited progradation. In contrast, the lower subsidence rate settings of the fault‐tip and hangingwall dip‐slope deltas mean that they are subject to relative sea‐level fall and associated fluvial incision and forced regression. Low gradients and tectonic tilting of the hangingwall influence the geometry of these deltas, with fault‐tip deltas preferentially prograding axially along the fault, creating elongate delta lobes. In contrast, broad, sheet‐like delta lobes characterize the hangingwall dip‐slope deltas. The model results suggest that different systems tracts may be coeval over length scales of several kilometres and that key stratal surfaces defining and subdividing depositional sequences may only be of local extent. Furthermore, the results highlight pitfalls in sequence‐stratigraphic interpretation and problems in interpreting controlling processes from the preserved stratigraphic product. 相似文献
20.
构造沉积学不仅强调大地构造背景条件对盆地演化的控制作用,同时还注重盆地内部的构造特征与沉积充填特征之间的控制及响应关系研究。陆相裂谷盆地发育过程中,构造作用强烈,盆地沉积充填过程复杂,进行构造沉积学研究对揭示盆地构造沉积演化过程具有重要意义。以大量地震、钻测井资料为基础,结合大地构造背景资料,研究松辽盆地伏龙泉断陷发育过程中的构造、沉积演化特征,分析构造活动与沉积作用之间的响应及控制关系,并由此讨论半地堑陆相湖盆的沉积充填演化规律及其控制因素。研究表明,在伏龙泉断陷盆地演化过程中,早期的火山岩隆起对盆地初始裂陷期形态具有明显的影响作用;边界断层的分布及其生长速率特征则对盆地结构演化过程起着首要的控制作用。盆地裂陷期,研究区古气候环境比较稳定,构造因素是控制该陆相裂谷盆地地层序列与沉积特征的首要因素;断裂发育特征决定了盆地的古地貌特征,而盆地的古地貌特征直接影响着盆地内部的沉积充填类型与沉积体系展布格局;区域构造抬升与断块掀斜是该半地堑盆地内部发育不整合面的主要因素。在陆相裂陷盆地的构造沉积特征研究中,构造沉积学显示出了其必要性与适用性,有利于在揭示构造沉积现象的同时,合理解释其地质成因。 相似文献