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1.
The Marnoso–arenacea basin was a narrow, northwest–southeast trending, foredeep of Middle–Late Miocene age bounded to the southwest by the Apennine thrust front. The basin configuration and evolution were strongly controlled by tectonics.

Geometrical and sedimentological analysis of Serravallian turbidites deposited within the Marnoso–arenacea foredeep, combined with palaeocurrent data (turbidite flow provenance, reflection and deflection), identify topographic irregularities in a basin plain setting in the form of confined troughs (the more internal Mandrioli sub-basin and the external S. Sofia sub-basin) separated by an intrabasinal structural high. This basin configuration was generated by the propagation of a blind thrust striking northwest to southeast, parallel to the main trend of the Apennines thrust belt.

Ongoing thrust-induced sea bed deformation, marked by the emplacement of large submarine landslides, drove the evolution of the two sub-basins. In an early stage, the growth and lateral propagation of a fault-related anticline promoted the development of open foredeep sub-basins that were replaced progressively by wedge-top or piggy-back basins, partially or completely isolated from the main foredeep. Meanwhile, the depocenter shifted to a more external position and the sub-basins were incorporated within an accretionary thrust belt.  相似文献   


2.
The Periadriatic foredeep (Italy) was generated by Neogene downbending of the Adria Plate under the Apennine Chain. The basin is filled with Plio-Pleistocene siliciclastic turbidites. Its substratum consists of the carbonate succession of the southwestern Adria Plate margin. The influence of the basin’s morphology on sedimentation and subsequent tectonic evolution is investigated in the Abruzzo sector of the foredeep (Cellino Basin). The substratum is composed of Messinian evaporites that dip towards the Apennines (W). A NNW component along the depocentral axis is divided into four blocks with different depths. The substratum was also affected by a Messinian extensional fault system, not involving the overlying Pliocene sequence. This morphology controlled the distribution of the turbidites in the lower part of the Cellino Basin. The Plio-Pleistocene compressional deformation of the foredeep produced an inner complex structure (Internal Structure), involving the foredeep substratum and an outer imbricate thrust system (Coastal Structure), detached over the faulted Messinian evaporites. This thrust system is parallel to the extensional faults, suggesting a strong influence of the substratum morphology on the development of the compressional structures. The overall structural setting was validated with a balanced cross-section. Out-of-sequence thrusting and non-coeval deformation within each thrust sheet characterize the local tectonic history.  相似文献   

3.
The space/time evolution of the Umbria-Romagna-Marche domains of the northern Apennine Miocene foredeep is proposed. In this period, the turbidite siliciclastic sedimentation is represented mainly by the Miocene Marnoso-Arenacea Formation, which generally ends with mainly marly deposits. From the internal Apennine sectors (Umbria-Romagna domain) to the external Adriatic Margin (Marche domain) the siliciclastic succession overlies hemipelagic marly deposits (Schlier Formation). The whole depositional area can be considered as a single wide basin with depocenter or main sedimentation areas progressively migrating eastwards. This basin is characterized by some morphological highs which did not constitute real dams for the sedimentary flows (turbidity currents). Multiple feeding (arkose, litharenites, calcarenites) from different sources is related to palaeogeographical and palaeotectonic reorganization of the most internal, previously deformed, Apennine areas. The activation of the foredeep stage is marked by the beginning of the siliciclastic sedimentation (Late Burdigalian in the most internal sector). This sedimentation ends in the most external sector in the Early Messinian, pointing to a depositional cycle of about 9?C10?Ma. The diachronism of the base of the siliciclastic deposition proves to be almost 5?Ma. The syn-depositional compressional deformation, which shows a marked diachronism, affected the internal area of the foredeep in the Early-Middle Serravallian, and progressively migrated up to Late Miocene, involving more and more external sectors. The deformed siliciclastic sedimentary wedge constitutes an orogenic pile incorporated in the Apennine Chain, represented by different tectonic elements superimposed by means of NE-vergent thrusts. The main stratigraphic and tectonic events of the Toscana-Romagna-Marche Apennines are presented in a general framework, resulting also in a terminological revision.  相似文献   

4.
A new genetic facies model for deep-water clastic evaporites is presented, based on work carried out on the Messinian Gessoso-solfifera Formation of the northern Apennines during the last 15 years. This model is derived from the most recent siliciclastic turbidite models and describes the downcurrent transformations of a parent flow mainly composed of gypsum clasts. The model allows clearer comprehension of processes controlling the production and deposition of clastic evaporites, representing the most common evaporite facies of the northern Apennines, and the definition of the genetic and stratigraphic relationship with primary shallow-water evaporites formed and preserved in marginal settings. Due to the severe recrystallization processes usually affecting these deposits, petrographic and geochemical analyses are needed for a more accurate interpretation of the large spectrum of recognized gravity-driven deposits ranging from debrisflow to low-density turbidites. Almost all the laminar ‘balatino’ gypsum, previously considered a deep-water primary deposit, is here reinterpreted as the fine-grained product of high to low-density gravity flows. Facies associations permit the framing of the distribution of clastic evaporites into the complex tectonically controlled depositional settings of the Apennine foredeep basin. The Messinian Salinity Crisis occurred during an intense phase of geodynamic reorganization of the Mediterranean area that also produced the fragmentation of the former Miocene Apennine foredeep basin. In this area, primary shallow-water evaporites equivalent to the Mediterranean Lower Evaporites, apparently only formed in semi-closed thrust-top basins like the Vena del Gesso Basin. The subsequent uplift and subaerial exposure of such basins ended the evaporite precipitation and promoted a widespread phase of collapse leading to the resedimentation of the evaporites into deeper basins. Vertical facies sequences of clastic evaporites can be interpreted in terms of the complex interplay between the Messinian tectonic evolution of the Apennine thrust belt and related exhumation–erosional processes. The facies model here proposed could be helpful also for better comprehension of other different depositional and geodynamic contexts; the importance of clastic evaporites deposits has been overlooked in the study of other Mediterranean areas. Based on the Apennine basins experience, it is suggested here that evaporites diffused into the deeper portions of the Mediterranean basin may consist mainly of deep-water resedimented deposits rather than shallow-water to supratidal primary evaporites indicative of a complete basin desiccation.  相似文献   

5.
Recognition of the occurrence and extent of hemipelagic and pelagic deposits in turbidite sequences is of considerable importance for environmental analysis (palaeodepth, circulation, distance from land, hemipelagic or pelagic versus turbidite sedimentation rates) of ancient basins. Differentiation between the finegrained parts (E-division) of turbidites and the (hemi-) pelagic layers (F-division of turbidite-pelagite alternations) is facilitated in basins where carbonate turbidites were deposited below the carbonate compensation depth (CCD) such as the Flysch Zone of the East Alps but may be difficult in other basins where less compositional contrast is developed between the fine-grained turbidites and hemipelagites. This difficulty pertains particularly in Palaeozoic and older basins. For Late Mesozoic-Cenozoic oceans with a relatively deep calcite compensation level three other types of turbidite basins may be distinguished for which differentiation becomes increasingly more difficult in the sequence from (1) to (3): (1) terrigenous turbidite basins above the CCD; (2) carbonate turbidite basins above the CCD; (3) terrigenous turbidite basins below the CCD. Criteria and methods useful for the differentiation between turbiditic and hemipelagic mudstone in the Upper Cretaceous of the Flysch Zone of the East Alps include calcium carbonate content, colour, sequential analysis, distribution of bioturbation, and microfaunal content. In modern turbidite basins clay mineral content, organic matter content, plant fragments, and grain-size (graded bedding, maximum grain diameter) have reportedly also been used as criteria (see Table 3). Deposition of muddy sediment by turbidity currents on weakly sloping sea bottoms such as the distal parts of deep-sea fans or abyssal plains is not only feasible but may lead to the accumulation of thick layers. Contrary to earlier speculation it can be explained by the hydrodynamic theory of turbidity currents, if temperature differences between the turbidity current and the ambient deep water as well as relatively high current velocities for the deposition of turbiditic muds (an order of magnitude higher on mud surfaces than commonly assumed) are taken into consideration. The former add to the capacity of turbidity currents to carry muddy sediment without creating a driving force on a low slope.  相似文献   

6.
The evolution of the oceanic Maghrebian Flysch Basin and its continuation in the Southern Apennines was studied by reconstructing mainly representative stratigraphic successions. In all sectors a common evolution has been identified. Rifting and drifting phases are indicated by remnants of oceanic crust, Jurassic limestones, Cretaceous–Palaeogene turbiditic and pelagic deposits. The pre-orogenic sedimentation was mainly controlled by extensional tectonics and sea-level changes. The occurrence of a generalized foredeep stage since the Early Miocene is testified by thick siliciclastic and volcaniclastic syn-orogenic flysch successions. The deformation of the oceanic areas began in the Burdigalian and the resulting nappes were stacked in the growing chains. During the Middle Miocene, piggy-back basins developed and the building of the chains was accomplished in the Late Tortonian. Areal distribution and ages of flysch deposits represent an important tool for the study of the diachronous growth of the accretionary wedges.  相似文献   

7.
This work presents the stratigraphy and facies analysis of an interval of about 2500 m in the Langhian and Serravallian stratigraphic succession of the foredeep turbidites of the Marnoso‐arenacea Formation. A high‐resolution stratigraphic analysis was performed by measuring seven stratigraphic logs between the Sillaro and Marecchia lines (60 km apart) for a total thickness of about 6700 m. The data suggest that the stratigraphy and depositional setting of the studied interval was influenced by syndepositional structural deformations. The studied stratigraphic succession has been subdivided into five informal stratigraphic units on the basis of how structurally controlled topographic highs and depocentres, a consequence of thrust propagation, change over time. These physiographic changes of the foredeep basin have also been reconstructed through the progressive appearance and disappearance of thrust‐related mass‐transport complexes and of five bed types interpreted as being related to structurally controlled basin morphology. Apart from Bouma‐like Type‐4 beds, Type‐1 tripartite beds, characterized by an internal slurry unit, tend to increase especially in structurally controlled stratigraphic units where intrabasinal topographic highs and depocentres with slope changes favour both mud erosion and decelerations. Type‐2 beds, with an internal slump‐type chaotic unit, characterize the basal boundary of structurally controlled stratigraphic units and are interpreted as indicating tectonic uplift. Type‐3 beds are contained‐reflected beds that indicate different degrees of basin confinement, while Type‐5 are thin and fine‐grained beds deposited by dilute reflected turbulent flows able to rise up the topographic highs. The vertical and lateral distribution of these beds has been used to understand the synsedimentary structural control of the studied stratigraphic succession, represented in the Marnoso‐arenacea Formation by subtle topographic highs and depocentres created by thrust‐propagation folds and emplacements of large mass‐transport complexes.  相似文献   

8.
ABSTRACT The Upper Carboniferous deep‐water rocks of the Shannon Group were deposited in the extensional Shannon Basin of County Clare in western Ireland and are superbly exposed in sea cliffs along the Shannon estuary. Carboniferous limestone floors the basin, and the basin‐fill succession begins with the deep‐water Clare Shales. These shales are overlain by various turbidite facies of the Ross Formation (460 m thick). The type of turbidite system, scale of turbidite sandstone bodies and the overall character of the stratigraphic succession make the Ross Formation well suited as an analogue for sand‐rich turbidite plays in passive margin basins around the world. The lower 170 m of the Ross Formation contains tabular turbidites with no channels, with an overall tendency to become sandier upwards, although there are no small‐scale thickening‐ or thinning‐upward successions. The upper 290 m of the Ross Formation consists of turbidites, commonly arranged in thickening‐upward packages, and amalgamated turbidites that form channel fills that are individually up to 10 m thick. A few of the upper Ross channels have an initial lateral accretion phase with interbedded sandstone and mudstone deposits and a subsequent vertical aggradation phase with thick‐bedded amalgamated turbidites. This paper proposes that, as the channels filled, more and more turbidites spilled further and further overbank. Superb outcrops show that thickening‐upward packages developed when channels initially spilled muds and thin‐bedded turbidites up to 1 km overbank, followed by thick‐bedded amalgamated turbidites that spilled close to the channel margins. The palaeocurrent directions associated with the amalgamated channel fills suggest a low channel sinuosity. Stacks of channels and spillover packages 25–40 m thick may show significant palaeocurrent variability at the same stratigraphic interval but at different locations. This suggests that individual channels and spillover packages were stacked into channel‐spillover belts, and that the belts also followed a sinuous pattern. Reservoir elements of the Ross system include tabular turbidites, channel‐fill deposits, thickening‐upward packages that formed as spillover lobes and, on a larger scale, sinuous channel belts 2·5–5 km wide. The edges of the belts can be roughly defined where well‐packaged spillover deposits pass laterally into muddier, poorly packaged tabular turbidites. The low‐sinuosity channel belts are interpreted to pass downstream into unchannellized tabular turbidites, equivalent to lower Ross Formation facies.  相似文献   

9.
Extensional deformations are common within foredeep basins and generally consist of hinterland-dipping normal faults located at the foredeep–foreland transition zones. Foreland-dipping normal faults at the belt–foredeep boundaries, by contrast, are far less documented and their occurrence is not predicted by simple orogenic load models. New surface data integrated with seismic reflection profiles across the Central Apennines of Italy reveal the occurrence of foreland-dipping normal faults located in the inner edges of foredeep depressions. Extensional deformations are systematically found within sequentially younger Tortonian, Messinian and Early Pliocene foredeep basins, thus suggesting that normal fault development was an intrinsic feature of the evolving belt–foredeep–foreland system and could have influenced the stratal architectures of the host syn-orogenic deposits. Foreland extension is consistent with existing geodynamic models for the Apennines and could represent the effects of lithospheric bending: its recognition and documentation elsewhere could provide significant insights to improve our understanding of syn-orogenic basin dynamics.  相似文献   

10.
Río Fardes剖面位于西班牙南部Granada东北,构造上属于深水环境的Subbetic中带。该剖面主要由白垩纪Fardes组第Ⅱ段和第Ⅲ段(半)远洋沉积构成,并出现浊流沉积和混杂沉积。本次研究在Fardes组浊流层序内首次发现两段红色沉积。钙质超微化石表明红层的时间从Turonian早期(UC7 带)到Coniacian中期—晚期界线(UC10/?UC11带)。红层由mm级红色泥岩夹灰色、杂色、偶尔黑色泥岩和钙质泥岩组成。沉积学研究表明新发现的Turonian Coniacian远洋红色泥岩沉积形成于CCD面之下深水盆地环境,浊流和碎屑流沉积强烈地影响着(半)远洋环境的背景泥岩相,并成为红色沉积结束的原因。  相似文献   

11.
Owing to its expanded stratigraphic sections, the Apennine thrust belt offers the opportunity to better understand the evaporitic and post-evaporitic Messinian events. A physical stratigraphic framework of Messinian deposits, based on facies analysis and basin-wide correlation of key surfaces and sedimentary cycles, is presented. It is shown that the Messinian Apennine foredeep had marginal basins with shallow-water primary evaporites and deeper basins where resedimented evaporites accumulated under relatively deep-water conditions. Like many other Mediterranean examples, primary shallow-water evaporites of Apenninic marginal basins show evidence for subaerial exposure and erosion. However, the development of such an erosional surface does not correspond to the deposition of primary evaporites in the deepest part of the basin(s); here, the unconformity can be traced towards the base of resedimented evaporites or to a level within them, implying that the deeper basins of the Apennine foredeep never underwent desiccation during the Messinian salinity crisis, but rather received the eroded marginal evaporites. This fact, usually overlooked, raises important questions about the deep desiccation model of the Mediterranean.  相似文献   

12.
The Cervarola Sandstones Formation, Aquitanian–Burdigalian in age, was deposited in an elongate, north‐west stretched foredeep basin formed in front of the growing northern Apennines orogenic wedge. As other Apennine foredeep deposits, such as the Marnoso‐arenacea Formation, the stratigraphic succession of the Cervarola Sandstones Formation records the progressive closure of the basin due to the propagation of thrust fronts towards the north‐east, i.e. towards the outer and shallower foreland ramp. This process produces a complex foredeep that is characterized by syn‐sedimentary structural highs and depocentres that strongly influence lateral and vertical turbidite facies distribution. This work describes and discusses this influence, providing a high‐resolution physical stratigraphy with ‘bed by bed’ correlations of an interval ca 1000 m thick, parallel and perpendicular to the palaeocurrents and to the main structural alignments, on an area of ca 30 km that covers the proximal portion of the Cervarola basin in the northern Apennines. The main aim is to show, for the first time ever, a detailed facies analysis of the Cervarola Sandstones Formation, based on a series of bed types that have proven fundamental to understand the morphology of the basin. The knowledge of the vertical and lateral distribution of these bed types, such as contained‐reflected and slurry (i.e. hybrid) beds, together with other important sedimentary structures, i.e. cross‐bedded bypass facies and delamination structures, is the basis for better understanding of facies processes, as well as for proposing an evolutionary model of the foredeep in relation to the syn‐sedimentary growth of the main tectonic structures. This makes the Cervarola Sandstones, like the Marnoso‐arenacea Formation, a typical example of foredeep evolution.  相似文献   

13.
The Devonian of East Greenland comprises a thick sequence of continental clastic sediments infilling an extensional basin. West of the main basin bounding fault (Western Fault Zone) are scattered outliers of Devonian conglomerate which accumulated in small basins such as found on the island, Ella Ø. The Ella Ø Basin formed by extensional movement along the Narhval Sund Fault accompanied by the formation of a prominent bedding parallel detachment surface which was subsequently modified by sub-aerial exposure to become the unconformity surface. Mapping of this unconformity surface shows major vertical relief. A thick sequence of conglomerate occurs on Ella Ø, which, close to its exposed basal unconformity, has three lacustrine beds intercalated within it. Detailed analysis of one lake unit shows it to have significant lateral variation. At proximal localities it largely comprises lacustrine turbidites, whereas more distal locations were within a stratified lake. The interpreted sequence of events on Ella Ø is an interval of fluvial sedimentation followed by rapid drowning of the topography with lacustrine sediments onlapping onto basement. After an interval of deeper lacustrine sedimentation including laminites, the lake shallowed, the lithology changed to limestone and the lake dried out. Conglomerate deposition then recommenced. Maximum lake water depth of 100 m is estimated following correction (7°) for post-Devonian rotation, both determined using the distribution of lacustrine sediments on the unconformity surface. The preferred mechanism for flooding of the Ella Ø Basin is episodic flooding of the entire basin system. Lacustrine sediment preservation results purely from its deposition amongst topography at the edge of the active fluvial system. In such fluvial systems lacustrine sediments may be part of the normal sedimentary cycle but were almost always removed by reworking.  相似文献   

14.
右江盆地层序格架中的生储盖组合特征及勘探意义   总被引：7，自引：0，他引：7  
在层序地层研究基础上,结合右江盆地油气勘探成果,建立了右江盆地层序地层格架与油气生储盖组合之间的关系模型。具体是以南盘江凹陷及十万大山地区为重点,通过泥盆纪-中三叠世层序地层中生储盖组合的研究,阐述相应的不同级别层序格架 (二级及三级 )中储集体的成因类型及时空分布规律,进而探讨不同成因层序中有利储集体的发育模式。  相似文献   

15.
基于对玻利维亚区域构造演化与沉积充填特征的分析,研究盆地烃源岩、储集层及盖层等油气成藏地质条件的差异,分析盆地勘探潜力。玻利维亚境内发育查科、贝尼和马德雷德迪奥斯等3个重点盆地,均是在前寒武系基底基础上发育起来的叠合盆地,盆内依次充填了古生代克拉通边缘海相沉积层序、三叠纪-白垩纪裂谷期海相-海陆过渡沉积层序和晚白垩世至今前陆陆相沉积层序。油气成藏地质条件综合对比分析认为,3个盆地均发育泥盆系主力烃源岩,储集层以泥盆系-石炭系和白垩系砂岩为主,发育古生界泥岩和碳酸盐岩及古近系泥岩等多套区域盖层。成熟烃源岩主要分布在冲断带和前渊区,油气必须通过垂向和侧向运移才能聚集成藏,具有晚期生烃、晚期成藏的特点。马德雷德迪奥斯盆地前渊-斜坡带低幅构造圈闭和地层圈闭、查科盆地和贝尼盆地逆冲褶皱带构造圈闭是主要的勘探目标。  相似文献   

16.
The San Andreas fault system in northern California forms an 80–90 km wide zone of right-lateral shear. Extensional tectonism within this broad shear zone is indicated by both Neogene silicic volcanic rocks that gradually young in the direction of shear propagation to the north-west and by numerous Neogene faultbounded structural basins filled with thick non-marine sequences. The Little Sulphur Creek basins, three well-exposed 1·5–2 km wide pull apart basins within this shear system, have sedimentation patterns analogous to those of much larger pull-apart basins. They were formed and subsequently deformed by east-west extension and by north-west to south-east-orientated right-slip concurrently with basin filling. Palaeocurrent and maximum-clast size data indicate both lateral sediment transport from fault-bounded basin margins and longitudinal transport down the basin axes. The basins are filled primarily with coarse alluvial-fan and streamflow deposits derived from a surrounding igneous, sedimentary, and metamorphic provenance. Two of the basins contain basin-plain-type lacustrine turbidites that grade laterally into distal alluvial fan, fan-delta, and sublacustrine delta deposits. Talus deposits along the south-west margin of the basins contain megabreccia indicative of active uplift. Structures indicative of dewatering, liquefaction, and slumping suggest penecontemporaneous tectonism.  相似文献   

17.
The International Ocean Discovery Program (IODP) Expedition 367/368 reported massive Upper Miocene deep-sea turbidite in the northern South China Sea basin. The Upper Miocene turbidite sand-bodies at Site U1500 were examined with detrital zircon U-Pb dating to conduct the source-to-sink analysis. This study shows that the U-Pb age spectrums of Site U1500 sample are similar to those detrital zircons from the Miocene Qiongdongnan Basin and the Pearl River Mouth Basin. Multidimensional scaling (MDS) plot also shows that the turbidite sand-bodies at Site U1500 are closely related to the sediments in the Pearl River Mouth Basin and Qiongdongnan Basin. It is likely that the thick deep-sea turbidite succession in the deep-water basin of northern South China Sea was formed by a mixed provenance pattern during the late Miocene. On the one hand, terrigenous sediments from the west of the South China Sea were transported along the Central Canyon to the eastern South China Sea deep-sea basin in the form of turbidity current. On the other hand, terrigenous sediments were also transported from the Pearl River through the slope canyon system to the northern South China Sea in the form of gravity flow . Those mixed sediments from two different source areas have collectively deposited at the deep-sea basin and thus, give rise to turbidite sequence of hundred meters. Provenance analysis of the thick turbidites sand-bodies in the deep-sea basin is of great significance to the profound understanding of the tectonic evolution, filling processes, provenance evolution, and the palaeogeographic characteristics of the Cenozoic basins of the South China Sea.  相似文献   

18.
源- 汇系统是目前国内外地球科学领域的研究热点,对于含油气盆地古地理重建以及源储预测评价有着重要的指导作用。本文以准噶尔盆地二叠系为研究对象,通过基于盆地地质大剖面的构造- 层序特征分析、定年数据的物源体系演化分析和沉积过程约束的正演模拟等方法,深化了对准噶尔盆地二叠纪古地理格局的认识,探讨了二叠纪源- 汇系统演化特征与二叠系源储分布规律。早二叠世为盆地断陷发育期,以石炭系为主物源,除东南部发育海相- 海陆过渡相沉积外,总体以近物源扇三角洲- 湖相沉积体系为主,多断陷的沉积格局控制了玛湖等凹陷优质烃源岩的分布,与火山岩相关的扇三角洲前缘砂体与混积云质岩构成有利储集体;中二叠世为盆地断- 拗转换期,物源年龄开始趋于复杂,沉积中心、沉降中心较早二叠世明显向盆内迁移,早期断陷趋于连通,盆地西部仍以近物源的扇三角洲群- 湖相沉积体系为主,东南部则转换为远物源三角洲群- 湖盆沉积体系,在盆地中部发育连片分布的规模烃源岩,可与同期（扇）三角洲前缘形成良好的源储组合;晚二叠世进入盆地拗陷发育期,物源供给范围更广,物源年龄进一步复杂化,大型浅水湖盆发育远物源为主的退覆型河流- 三角洲沉积体系,为盆地规模油气成藏奠定了储层基础。  相似文献   

19.
IODP367/368航次在南海北部深海盆地多个站位发现上中新统厚达数百米的大规模深海浊积岩。采用碎屑锆石U-Pb年龄谱系分析方法对U1500站上中新统浊积砂体进行源汇对比分析。研究结果表明U1500站上中新统浊积岩碎屑锆石年龄谱系与其西侧琼东南盆地和北侧珠江口盆地中新世沉积物特征类似。多维排列分析(MDS)结果也显示,该站位样品与珠江口盆地、琼东南盆地沉积物关系密切,表明南海北部深海盆地内厚达数百米的上中新统浊积砂体为南海北部物源和南海西部物源混合堆积形成。南海西部陆源输入物质以浊流搬运的方式,沿中央峡谷从西到东搬运至南海东部深海盆地;南海北部珠江物源以重力流的形式,经南海北部陆坡峡谷搬运至深海盆地中,两种来源的沉积物在深海盆地发生混合沉积,形成U1500站厚达数百米的浊积砂体。南海北部深海盆地厚层浊积砂体物质来源的准确识别,对深刻理解南海新生代盆地的构造演化、沉积物充填过程、物源演变以及古地理特征均具有重要意义。  相似文献   

20.
以库车前陆盆地为例,对陆相前陆盆地的形成、沉积充填与层序地层结构、不整合面与层序界面、层序地层组成与其模式、生储盖组合与岩性地层圈闭等关键问题进行了探讨。认为前陆层序是盆缘构造运动的响应,由低位(冲积)体系域、湖侵体系域、高位体系域组成。前陆盆地层序界面表现为构造或沉积不整合面,代表了一次构造幕的发生,其层序地层样式是盆缘造山带构造楔推进作用的结果,是盆地演化的不同阶段的响应,反映了构造运动由强到弱的间歇变化。前陆层序界面代表了沉积结构的大转换,之下为构造稳定阶段的湖相泥岩或膏泥岩,之上为代表构造运动的冲积扇—扇三角洲相的巨厚磨拉石沉积充填。在构造活动期和静止期,盆地不同位置形成不同的沉积充填和地层结构特点。构造活动期以低位(冲积)体系域为主,在毗邻造山带侧以巨厚的冲积扇-扇三角洲-辫状河三角洲相等冲积沉积物为主;构造静止期以湖侵体系域为主,为广泛的河流-湖泊相沉积。沉积厚度从靠近冲断带侧向盆地内逐渐变小。陆相前陆盆地的生储盖组合配置好,储集体广泛分布于低位、湖侵和高位体系域中,以辫状河三角洲和滨湖相为主。其岩性地层圈闭主要分布在前缘斜坡带上,包括沿古隆起边缘的地层超覆不整合圈闭和地层削蚀不整合圈闭,将会成为今后油气勘探的新领域。  相似文献   

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