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1.
Marginal marine deposits of the John Henry Member, Upper Cretaceous Straight Cliffs Formation, were deposited within a moderately high accommodation and high sediment supply setting that facilitated preservation of both transgressive and regressive marginal marine deposits. Complete transgressive–regressive cycles, comprising barrier island lagoonal transgressive deposits interfingered with regressive shoreface facies, are distinguished based on their internal facies architecture and bounding surfaces. Two main types of boundaries occur between the transgressive and regressive portions of each cycle: (i) surfaces that record the maximum regression and onset of transgression (bounding surface A); and (ii) surfaces that place deeper facies on top of shallower facies (bounding surface B). The base of a transgressive facies (bounding surface A) is defined by a process change from wave‐dominated to tide‐dominated facies, or a coaly/shelly interval indicating a shift from a regressive to a transgressive regime. The surface recording such a process change can be erosional or non‐erosive and conformable. A shift to deeper facies occurs at the base of regressive shoreface deposits along both flooding surfaces and wave ravinement surfaces (bounding surface B). These two main bounding surfaces and their subtypes generate three distinct transgressive – regressive cycle architectures: (i) tabular, shoaling‐upward marine parasequences that are bounded by flooding surfaces; (ii) transgressive and regressive unit wedges that thin basinward and landward, respectively; and (iii) tabular, transgressive lagoonal shales with intervening regressive coaly intervals. The preservation of transgressive facies under moderately high accommodation and sediment supply conditions greatly affects stratigraphic architecture of transgressive–regressive cycles. Acknowledging variation in transgressive–regressive cycles, and recognizing transgressive successions that correlate to flooding surfaces basinward, are both critical to achieving an accurate sequence stratigraphic interpretation of high‐frequency cycles. 相似文献
2.
Sedimentary response to Late Quaternary sea-level changes in the Romagna coastal plain (northern Italy) 总被引：5，自引：0，他引：5
Data from 17 continuously cored boreholes, 40–170 m deep, reveal the subsurface stratigraphy of the Romagna coastal plain. Sedimentological and microfaunal data allow the distinction of eight facies associations of Late Pleistocene–Holocene age, including 18 lithofacies and 16 faunal associations. Ten 14C dates provide the basis to establish a sequence stratigraphic framework for the succession corresponding to the upper part 35 ky BP of the last glacio-eustatic cycle. The eight facies associations can be grouped into lowstand, transgressive and highstand systems tracts. The upper part of the lowstand systems tract consists of alluvial plain deposits. These accumulated during the Late Pleistocene when the shoreline was ≈250 km south of its present-day position. A pronounced stratigraphic hiatus (between 25 and 8·8 ky BP) is invariably recorded at the upper boundary (transgressive surface) of these Pleistocene, indurated and locally pedogenized alluvial deposits. The succeeding postglacial history is represented by a well developed transgressive–regressive cycle. Transgressive deposits, interpreted to reflect the rapid landward migration of a barrier–lagoon system, include two wedge-shaped, paralic and marine units. These thicken in opposite directions and are separated by a ravinement surface. Above the transgressive deposits, the maximum flooding surface (MFS) marks the change from a transgressive barrier–lagoon complex to a prograding, wave-dominated delta system (early Po delta). The MFS can be traced landwards, where it constitutes the base of lagoonal deposits. An aggradational to progradational stacking pattern of upper delta plain (marsh), lower delta plain (lagoon/bay), and delta front (beach ridge) deposits reflects the progressive increase in the sediment supply/accommodation ratio during the following highstand. The alluvial deposits capping the sequence accumulated by the 13th century AD, in response to an avulsion event that caused abandonment of the former Po delta lobe and the northward migration of the Po River towards its present position. 相似文献
3.
The Late Eocene-Early Oligocene sedimentary fill of the Lemnos Island, NE Greece, is represented by a submarine fan and shelf
deposits. Turbidites in the system occur as a laterally isolated body, with one sediment influx center present. The influx
center is a proximal distributary channel that occupies a position approximately in the fan’s center and displays the coarsest
sediment in the study area. It also suggests in association with the main palaeocurrent direction toward NE a curved shape
for the fan. The stratigraphic succession of the submarine fans indicates that their sedimentation started during the base
level fall and completed shortly after the base level rise. As a consequence, the study area was filled by turbidites that
correspond to forced regressive, lowstand normal regressive, and transgressive genetic units. The progradational bedsets,
within the basal part of the turbidite deposits, recorded the history of the base level fall. The mixed progradational/aggradational
style of the upper part of the submarine fan system suggests that the regression of the shoreline is driven by sediment supply
during a period of base-level rise at the shoreline, or at a time of baselevel stillstand. The overlying shelf facies consist
of thick to medium bedded sandstones and mudstones, which display a general thinning upward trend. The base of the mudstone
facies that overlie the thick-bedded, amalgamated sandstones corresponds to a transgressive surface. This surface separates
the low-stand deposits (thick-bedded sandstones) from the high stand deposits (mudstone facies), suggesting that deposition
of shelf facies occurred during a transgressive system tract. 相似文献
4.
The Eocene Trihueco Formation is one of the best exposed successions of the Arauco Basin in Chile. It represents a period of marine regression and transgression of second-order duration, during which barrier island complexes developed on a muddy shelf. The strata are arranged in classical shoaling-upward parasequences of shoreface and beach facies capped by coal-bearing, back-barrier lagoon deposits. These fourth-order cycles are superimposed upon third-order cycles which caused landward and seaward shifts of the coastal facies belts. The final, punctuated rise in sea level is represented by shelf mudrocks with transgressive incised shoreface sandstones. Relative sea-level oscillations as revealed in the stratigraphy of the Trihueco Formation show a reasonable correlation with published Eocene eustatic curves. 相似文献
5.
The mid-Cenomanian Dunvegan Formation represents a delta complex deposited on a foreland basin ramp over about 2 my. The Dunvegan is divided into 10 transgressive–regressive allomembers, labelled J–A in ascending order, each defined by regional marine transgressive surfaces. Parasequences within allomembers show an aggradational to offlapping stacking pattern that reflects alternate generation and removal of accommodation. The upper surfaces of allomembers H–E are incised by extensive valley systems traceable for up to 320 km and over about 50 000 km2. Valley depths range up to 41 m and can change significantly over short distances. However, the average depth of incision (mean 21 m) shows no systematic variation in longitudinal profiles and no evidence of headward shallowing. Valleys are typically 1–2 km wide, but locally widen to about 8 km. Widening is sometimes associated with confluence zones, but elsewhere it is not. Updip reaches of valleys are dominated by cross-bedded fluvial sandstone forming multistorey point-bar deposits. Sandstones contain widespread but uncommon paired carbonaceous drapes recognizable as tidal bundles. Inclined heterolithic stratification is locally well developed at the top of the valley fill. Downdip reaches of valleys, typically within 50 km of the lowstand shoreline, have a sandstone-dominated lower part and, locally, a mud-rich upper portion consisting of a variety of laminated heterolithic facies with a clear tidal signature. These heterolithic deposits may represent central basin, tidal flat, bayhead delta and point-bar environments. Valley filling took place mainly during the transgressive systems tract (TST) when tidally influenced environments migrated upvalley. Semi-diurnal tidal backwater effects extended at least 30 km landward of the regional maximum transgressive marine shoreline. The aggradational late TST and highstand systems tract (HST) includes deltaic and coastal plain deposits comprising lake and anastomosed river deposits that suggest a very low gradient (≈ 1:3000). Delta parasequences of the falling stage systems tract (FSST) offlap seaward and have no equivalent coastal plain deposits. The FSST has an average width of 60 km and an inferred gradient of 1:2500. The upper surfaces of the HST and FSST are extensively incised by valleys. The lowstand systems tract (LST) is subtly aggradational, lacks valleys and is characterized by large delta lobes fed by major distributaries. The width and inferred slope of the FSST, coupled with the thickness of aggradational TST and HST deposits on the coastal plain, suggest a vertical accommodation of about 35 m per transgressive event. About 11 m of this is attributed to isostatic subsidence resulting from water and sediment loads; the residual 24 m is attributed to eustatic rise. This sea-level change is of the same order of magnitude as the valley depths. The length of valleys, however, does not seem to be explicable solely in terms of downstream forcing by sea-level change, and an additional, upstream-forcing mechanism, possibly related to precipitation cycles in the Milankovitch band, might be inferred. 相似文献
6.
The Neoproterozoic and Palaeozoic Taoudeni basin forms the flat-lying and unmetamorphosed sedimentary cover of the West African Craton. In the western part of this basin, the Char Group and the lower part of the Atar Group make up a 400-m-thick Neoproterozoic siliciclastic succession which rests on the Palaeoproterozoic metamorphic and granitic basement. Five erosional bounding surfaces of regional extent have been identified in this succession. These surfaces separate five stratigraphic units with lithofacies associations ranging from fluvial to coastal and fluvial-, tide-, or wave-dominated shallow marine deposits. Owing to their regional extent and their position within the succession, the erosive bounding surfaces correspond to relative sea-level falls, and accordingly the five stratigraphic units they bound represent allocyclic transgressive–regressive depositional sequences (S1–S5). Changes in the nature of the deposits forming the transgressive–regressive cycles reflect landward or seaward shifts of the stacked sequences. These successive relative sea-level changes are related to the reactivation of basement faults and tilting during rifting of the Pan-Afro-Brasiliano supercontinent 1000 m.y. ago. The stromatolite bearing carbonate-shale sequences which form the rest of the Atar Group mark the onset of a quiet period of homogeneous subsidence contemporaneous with the Pan-African I oceanization 800–700 m.y. ago. 相似文献
7.
STEPHEN T. ABBOTT 《Sedimentology》1997,44(5):805-824
Richly fossiliferous and disconformity-bounded facies successions, termed Mid-Cycle Condensed Shellbeds (MCS), occupy a mid-cycle position within depositional sequences in the Castlecliff section (mid-Pleistocene, Wanganui Basin, New Zealand). These shell-rich intervals (0.1–4.5 m thick) comprise the upper of two loci of shell accumulation in Castlecliff sequences. The lower disconformable contacts are sharp and variably burrowed, and are interpreted as submarine transgressive surfaces formed by storm or tidal current erosion at the feather-edge of contemporary transgressive systems tracts. Above (i.e. seaward) of this erosion surface, macrofossil remains (mainly bivalves and gastropods) accumulated, with little reworking, on the inner-shelf under conditions of reduced terrigenous sediment supply. The upper contacts are sharp transitions from shell-rich to relatively shell-poor lithofacies; parautochthonous shell accumulation was ‘quenched’by downlapping highstand systems tract shelf siltstones and muddy fine sandstones. Castlecliff MCS, together with the basal shell-rich part of overlying highstand systems tracts, occupy a stratigraphic position which corresponds to the condensed section that forms at the transgressive/highstand systems tract boundary in the sequence model of Haq et al. (1987). Palaeoenvironmental analysis indicates that Castlecliff MCS are substantially, if not entirely, transgressive deposits. This study therefore shows that the ‘condensation maximum’within a depositional sequence does not necessarily bracket the transgressive systems tract/highstand systems tract boundary. 相似文献
8.
The Lower Jurassic Mashabba Formation crops out in the core of the doubly plunging Al-Maghara anticline, North Sinai, Egypt. It represents a marine to terrestrial succession deposited within a rift basin associated with the opening of the Neotethys. Despite being one of the best and the only exposed Lower Jurassic strata in Egypt, its sedimentological and sequence stratigraphic framework has not been addressed yet. The formation is subdivided informally into a lower and upper member with different depositional settings and sequence stratigraphic framework. The sedimentary facies of the lower member include shallow-marine, fluvial, tidal flat and incised valley fill deposits. In contrast, the upper member consists of strata with limited lateral extension including fossiliferous lagoonal limestones alternating with burrowed deltaic sandstones. The lower member contains three incomplete sequences (SQ1-SQ3). The depositional framework shows transgressive middle shoreface to offshore transition deposits sharply overlain by forced regressive upper shoreface sandstones (SQ1), lowstand fluvial to transgressive tidal flat and shallow subtidal sandy limestones (SQ2), and lowstand to transgressive incised valley fills and shallow subtidal sandy limestones (SQ3). In contrast, the upper member consists of eight coarsening-up depositional cycles bounded by marine flooding surfaces. The cycles are classified as carbonate-dominated, siliciclastic-dominated, and mixed siliciclastic-carbonate. The strata record rapid changes in accommodation space. The unpredictable facies stacking pattern, the remarkable rapid facies changes, and chaotic stratigraphic architecture suggest an interplay between allogenic and autogenic processes. Particularly syndepositional tectonic pulses and occasional eustatic sea-level changes controlled the rate and trends of accommodation space, the shoreline morphology, the amount and direction of siliciclastic sediment input and rapid switching and abandonment of delta systems. 相似文献
9.
《Sedimentary Geology》2006,183(1-2):1-13
Integrated sedimentological and micropaleontological (foraminifers and ostracods) analyses of two 55 m long borehole cores (S3 and S4) drilled in the subsurface of Lesina lagoon (Gargano promontory—Italy) has yielded a facies distribution characteristic of alluvial, coastal and shallow-marine sediments. Stratigraphic correlation between the two cores, based on strong similarity in facies distribution and AMS radiocarbon dates, indicates a Late Pleistocene to Holocene age of the sedimentary succession.Two main depositional sequences were deposited during the last 60-ky. These sequences display poor preservation of lowstand deposits and record two major transgressive pulses and subsequent sea-level highstands. The older sequence, unconformably overlying a pedogenized alluvial unit, consists of paralic and marine units (dated by AMS radiocarbon at about 45–50,000 years BP) that represent the landward migration of a barrier-lagoon system. These units are separated by a ravinement surface (RS1). Above these tansgressive deposits, highstand deposition is characterised by progradation of the coastal sediments.The younger sequence, overlying an unconformity of tectonic origin, is a 10 m-thick sedimentary body, consisting of fluvial channel sediments overlain by transgressive–regressive deposits of Holocene age. A ravinement surface (RS2), truncating the transgressive (lagoonal and back-barrier) deposits in core S4, indicates shoreface retreat and landward migration of the barrier/lagoon system. The overlying beach, lagoon and alluvial deposits are the result of mid-Holocene highstand sedimentation and coastal progradation. 相似文献
10.
PIRET PLINK-BJÖRKLUND 《Sedimentology》2005,52(2):391-428
Eighteen coastal-plain depositional sequences that can be correlated to shallow- to deep-water clinoforms in the Eocene Central Basin of Spitsbergen were studied in 1 × 15 km scale mountainside exposures. The overall mud-prone (>300 m thick) coastal-plain succession is divided by prominent fluvial erosion surfaces into vertically stacked depositional sequences, 7–44 m thick. The erosion surfaces are overlain by fluvial conglomerates and coarse-grained sandstones. The fluvial deposits show tidal influence at their seaward ends. The fluvial deposits pass upwards into macrotidal tide-dominated estuarine deposits, with coarse-grained river-dominated facies followed further seawards by high- and low-sinuosity tidal channels, upper-flow-regime tidal flats, and tidal sand bar facies associations. Laterally, marginal sandy to muddy tidal flat and marsh deposits occur. The fluvial/estuarine sequences are interpreted as having accumulated as a series of incised valley fills because: (i) the basal fluvial erosion surfaces, with at least 16 m of local erosional relief, are regional incisions; (ii) the basal fluvial deposits exhibit a significant basinward facies shift; (iii) the regional erosion surfaces can be correlated with rooted horizons in the interfluve areas; and (iv) the estuarine deposits onlap the valley walls in a landward direction. The coastal-plain deposits represent the topset to clinoforms that formed during progradational infilling of the Eocene Central Basin. Despite large-scale progradation, the sequences are volumetrically dominated by lowstand fluvial deposits and especially by transgressive estuarine deposits. The transgressive deposits are overlain by highstand units in only about 30% of the sequences. The depositional system remained an estuary even during highstand conditions, as evidenced by the continued bedload convergence in the inner-estuarine tidal channels. 相似文献
11.
Strata of the Bardas Blancas Formation (lower Toarcian–lower Bajocian) are exposed in northern Neuquén Basin. Five sections have been studied in this work. Shoreface/delta front to offshore deposits predominate in four of the sections studied exhibiting a high abundance of hummocky cross-stratified, horizontally bedded and massive sandstones, as well as massive and laminated mudstones. Shell beds and trace fossils of the mixed Skolithos-Cruziana ichnofacies appear in sandstone beds, being related with storm event deposition. Gravel deposits are frequent in only one of these sections, with planar cross-stratified, normal graded and massive orthoconglomerates characterizing fan deltas interstratified with shoreface facies. A fifth outcrop exhibiting planar cross-stratified orthoconglomerates, pebbly sandstones with low-angle stratification and laminated mudstones have been interpreted as fluvial channel deposits and overbank facies. The analysis of the vertical distribution of facies and the recognition of stratigraphic surfaces in two sections in Río Potimalal area let recognized four transgressive–regressive sequences. Forced regressive events are recognized in the regressive intervals. Comparison of vertical distribution of facies also shows differences in thickness in the lower interval among the sections studied. This would be related to variations in accommodation space by previous half-graben structures. The succession shows a retrogradational arrangement of facies related with a widespread transgressive period. Lateral variation of facies let recognize the deepening of the basin through the southwest. 相似文献
12.
MASSIMO ZECCHIN DARIO CIVILE MAURO CAFFAU GIOVANNI STURIALE CESARE RODA 《Sedimentology》2011,58(2):442-477
The Cutro Terrace is a mixed marine to continental terrace, where deposits up to 15 m thick discontinuously crop out in an area extending for ca 360 km2 near Crotone (southern Italy). The terrace represents the oldest and highest terrace of the Crotone area, and it has been ascribed to marine isotope stage 7 (ca 200 kyr bp ). Detailed facies and sequence‐stratigraphic analyses of the terrace deposits allow the recognition of a suite of depositional environments ranging from middle shelf to fluvial, and of two stacked transgressive–regressive cycles (Cutro 1 and Cutro 2) bounded by ravinement surfaces and by surfaces of sub‐aerial exposure. In particular, carbonate sedimentation, consisting of algal build‐ups and biocalcarenites, characterizes the Cutro 1 cycle in the southern sector of the terrace, and passes into shoreface and foreshore sandstones and calcarenites towards the north‐west. The Cutro 2 cycle is mostly siliciclastic and consists of shoreface, lagoon‐estuarine, fluvial channel fill, floodplain and lacustrine deposits. The Cutro 1 cycle is characterized by very thin transgressive marine strata, represented by lags and shell beds upon a ravinement surface, and thicker regressive deposits. Moreover, the cycle appears foreshortened basinwards, which suggests that the accumulation of its distal and upper part occurred during forced regressive conditions. The Cutro 2 cycle displays a marked aggradational component of transgressive to highstand paralic and continental deposits, in places strongly influenced by local physiography, whereas forced regressive sediments are absent and probably accumulated further basinwards. The maximum flooding shoreline of the second cycle is translated ca 15 km basinward with respect to that of the first cycle, and this reflects a long‐term regressive trend mostly driven by regional uplift. The stratigraphic architecture of the Cutro Terrace deposits is the result of the interplay between regional uplift and high amplitude, Late Quaternary glacio‐eustatic changes. In particular, rapid transgressions, linked to glacio‐eustatic rises that outpaced regional uplift, favoured the accumulation of thin transgressive marine strata at the base of the two cycles. In contrast, the combined effect of glacio‐eustatic falls and regional uplift led to high‐magnitude forced regressions. The superposition of the two cycles was favoured by a relatively flat topography, which allowed relatively complete preservation of stratal geometries that record large shoreline displacements during transgression and regression. The absence of a palaeo‐coastal cliff at the inner margin of the terrace supports this interpretation. The Cutro Terrace provides a case study of sequence architecture developed in uplifting settings and controlled by high‐amplitude glacio‐eustatic changes. This case study also demonstrates how the interplay of relative sea‐level change, sediment supply and physiography may determine either the superposition of cycles forming a single terrace or the formation of a staircase of terraces each recording an individual eustatic pulse. 相似文献
13.
This work presents the first detailed facies analysis of the upper Nyalau Formation exposed around Bintulu, Sarawak, Malaysia. The Lower Miocene Nyalau Formation exposures in NW Sarawak represent one of the closest sedimentological outcrop analogues to the age equivalent, hydrocarbon-bearing, offshore deposits of the Balingian Province. Nine types of facies associations are recognised in the Nyalau Formation, which form elements of larger-scale facies successions. Wave-dominated shoreface facies successions display coarsening upward trends from Offshore, into Lower Shoreface and Upper Shoreface Facies Associations. Fluvio-tidal channel facies successions consist of multi-storey stacks of Fluvial-Dominated, Tide-Influenced and Tide-Dominated Channel Facies Associations interbedded with minor Bay and Mangrove Facies Associations. Estuarine bay facies successions are composed of Tidal Bar and Bay Facies Associations with minor Mangrove Facies Associations. Tide-dominated delta facies successions coarsen upward from an Offshore into the Tidal Bar Facies Association. The Nyalau Formation is interpreted as a mixed wave- and tide-influenced coastal depositional system, with an offshore wave-dominated barrier shoreface being incised by laterally migrating tidal channels and offshore migrating tidal bars. Stratigraphic successions in the Nyalau Formation form repetitive high frequency, regressive–transgressive cycles bounded by flooding surfaces, consisting of a basal coarsening upward, wave-dominated shoreface facies succession (representing a prograding barrier shoreface and/or beach-strandplain) which is sharply overlain by fluvio-tidal channel, estuarine bay or tide-dominated delta facies successions (representing more inshore, tide-influenced coastal depositional environments). An erosion surface separates the underlying wave-dominated facies succession from overlying tidal facies successions in each regressive–transgressive cycle. These erosion surfaces are interpreted as unconformities formed when base level fall resulted in deep incision of barrier shorefaces. Inshore, fluvio-tidal successions above the unconformity display upward increase in marine influence and are interpreted as transgressive incised valley fills. 相似文献
14.
A thick Maastrichtian‐Ypresian succession, dominated by marine siliciclastic and carbonate deposits of the regionally recognized Nile Valley and Garra El‐Arbain facies associations, is exposed along the eastern escarpment face of Kharga Oasis, located in the Western Desert of Egypt. The main objectives of the present study are: (i) to establish a detailed biostratigraphic framework; (ii) to interpret the depositional environments; and (iii) to propose a sequence stratigraphic framework in order to constrain the palaeogeographic evolution of the Kharga sub‐basin during the Maastrichtian‐Ypresian time interval. The biostratigraphic analysis suggests the occurrence of 10 planktonic zones; two in the Early Maastrichtian (CF8b and CF7), four in the Palaeocene (P2, P3, P4c and P5) and four in the Early Eocene (E1, E2, E3 and E4). Recorded zonal boundaries and biostratigraphic zones generally match with those proposed elsewhere in the region. The stratigraphic succession comprises seven third‐order depositional sequences which are bounded by unconformities and their correlative conformities which can be correlated within and outside Egypt. These depositional sequences are interpreted as the result of eustatic sea‐level changes coupled with local tectonic activities. Each sequence contains a lower retrogradational parasequence set bounded above by a marine‐flooding surface and an upper progradational parasequence set bounded above by a sequence boundary. Parasequences within parasequence sets are stacked in landward‐stepping and seaward‐stepping patterns indicative of transgressive and highstand systems tracts, respectively. Lowstand systems tracts were not developed in the studied sections, presumably due to the low‐relief ramp setting. The irregular palaeotopography of the Dakhla Basin, which was caused by north‐east to south‐west trending submerged palaeo‐highs and lows, together with the eustatic sea‐level fluctuations, controlled the development and location of the two facies associations in the Kharga Oasis, the Nile Valley (open marine) and Garra El‐Arbain (marginal marine). 相似文献
15.
沉积盆地的层序和沉积充填结构及过程响应 总被引：13，自引：4，他引：9
现代层序地层学的理论发展,把沉积过程纳入到地质演化的时空框架中并与地球的多旋回或节律演化结合研究,形成了一套带有革命性的、在等时地层格架中研究沉积作用的新方法,成为了油气资源等沉积矿产预测勘探的重要工具。沉积盆地的沉积充填可划分出与各级沉积旋回相对应的层序地层单元。追踪对比由不整合面或不整合面及其对应的整合面为界的高级别层序地层单元建立的区域性等时地层格架,对盆地构造古地理再造和油气勘探战略性研究至关重要;追踪四、五级等低级别层序地层单元和体系域建立的高精度层序地层格架,可为重点区域或区带的沉积体系和储集体的沉积构成和分布等的解剖提供精细的地层对比基础。依据沉积基准面的变化,从层序内水进到水退的沉积旋回中可划分出正常水退沉积、强制性水退沉积、水进沉积及垂向加积等成因沉积类型。海相或湖相盆地中三级层序地层单元内均可较好地划分出低位、水进、高位及下降体系域。盆地构造作用、气候变化、海、湖平面升降过程对层序发育的控制作用及沉积响应研究,一直是层序地层学或沉积地质分析领域的研究热点。沉积盆地的层序地层序列演化是盆地地球动力学过程的总体响应。层序地层学把盆地古构造、古地理的变迁纳入到统一的地球演化系统中研究,形成了与区域地球演化史或盆地动力学演化相结合的重要研究领域。多旋回盆地或叠合盆地中多期次的构造变革导致了多个区域性不整合面所分隔的多个构造层序的叠加。注重构造—层序地层的结合分析,揭示盆地的层序地层序列与多期盆地构造作用的成因联系,是构造活动盆地或大型叠合盆地沉积地质演化和油气聚集规律研究的关键。盆地构造作用,如前陆盆地多期次的逆冲挠曲沉降和回弹隆起的构造作用、多幕裂陷过程、多期构造反转等与重要不整合及区域性沉积旋回或层序的形成密切相关;而由气候变化引起的海或湖平面变化是控制高频沉积旋回或低级别层序发育的主要因素。在构造活动盆地中,构造坡折带对沉积体系域和沉积相的发育分布具重要控制作用。 相似文献
16.
The Haystack Mountains Formation (Campanian, Mesaverde Group, US Western Interior Basin, Wyoming) contains a series of shallow-marine sandbodies, extending tens of kilometres out from a basin margin. The study succession (around 200 m thick) is composed of eight major sandstone tongues (Bolten Ranch, O'Brien Spring, Seminoe 1–2–3–4, Hatfield 1 and 2 members), each partially encased within marine shale intervals. The Formation is ‘sequential’at several scales. At the largest scale, the whole succession presents an aggradational to basinward-stepping stacking pattern of the sandstone tongues. At a lower level, each tongue (member) is characterized internally by two different types of lithosome: the first represents shoreface progradation with hummocky cross-strata passing up to swaley and trough cross-stratified sandstones. This lithosome is erosively truncated at its top in most cases, and has a general sheet-like geometry along strike, whereas down dip it displays a series of sharp-bounded clinothems. The latter sometimes indicate a downward as well as a basinward shift through time, as suggested by the occurrence of coarser and/or shallower facies at a lower level in the shoreface profile. The second type of lithosome is sheet- or wedge-like and sharply overlies the shoreface deposits. The lithosome consists of laterally widespread units of planar tabular to trough cross-bedded medium sandstones passing laterally (in a dip direction) into bioturbated sandstones. The lower part of this lithosome is progradational, becoming retrogradational into the overlying shales. The facies within the cross-bedded lithosome suggest a tidally dominated delta front to estuarine depositional setting. The two types of lithosome are not related genetically. The erosion surface separating the two lithosomes is a sequence boundary separating forced-regressive (relative sea-level fall) shoreface deposits from lowstand to transgressive (early relative sea-level rise), cross-bedded deposits. The uppermost part of the cross-stratified lithosome shows a landward-stepping of component parasequences and is abruptly blanketed by open-marine shales. The most widespread cross-bedded lithosomes are apparently best developed in the lowermost members of the Haystack Mountains Formation, i.e. in the aggradational part of the large-scale progradational succession. In the uppermost, highly progradational sandstone tongues, the shoaling-upward shoreface lithosome dominates, whereas the cross-bedded lithosome occurs in narrow, lensoid belts, or is absent. The middle portion of the succession shows intermediate characteristics. The vertical variation in geometry, thickness and progradational extent of successive cross-bedded lithosomes results from greater confinement of the incised nearshore systems both in space (landward direction) and in time (from the aggradation to the progradation architecture). The latter is a consequence of a decreasing rate of accommodation creation through time. 相似文献
17.
The Travenanzes Formation is a terrestrial to shallow‐marine, siliciclastic–carbonate succession (200 m thick) that was deposited in the eastern Southern Alps during the Late Triassic. Sedimentary environments and depositional architecture have been reconstructed in the Dolomites, along a 60 km south–north transect. Facies alternations in the field suggest interfingering between alluvial‐plain, flood‐basin and shallow‐lagoon deposits, with a transition from terrestrial to marine facies belts from south to north. The terrestrial portion of the Travenanzes Formation consists of a dryland river system, characterized by multicoloured floodplain mudstones with scattered conglomeratic fluvial channels, merging downslope into small ephemeral streams and sheet‐flood sandstones, and losing their entire discharge subaerially before the shoreline. Calcic and vertic palaeosols indicate an arid/semi‐arid climate with strong seasonality and intermittent discharge. The terrestrial/marine transition shows a coastal mudflat, the flood basin, which is usually exposed, but at times is inundated by both major river floods and sea‐water storm surges. Locally coastal sabkha deposits occur. The marine portion of the Travenanzes Formation comprises carbonate tidal‐flat and shallow‐lagoon deposits, characterized by metre‐scale shallowing‐upward peritidal cycles and subordinate intercalations of dark clays from the continent. The depositional architecture of the Travenanzes Formation suggests an overall transgressive pattern organized in three carbonate–siliciclastic cycles, corresponding to transgressive–regressive sequences with internal higher‐frequency sedimentary cycles. The metre‐scale sedimentary cyclicity of the Travenanzes Formation continues without a break in sedimentation into the overlying Dolomia Principale. The onset of the Dolomia Principale epicontinental platform is marked by the exhaustion of continental sediment supply. 相似文献
18.
Sedimentology and lithostratigraphy of Upper Eocene sponge‐rich sediments,southern Western Australia
P. R. Gammon N. P. James J. D. A. Clarke Y. Bone 《Australian Journal of Earth Sciences》2013,60(6):1087-1103
Late Eocene time in the Bremer and western Eucla Basins of southern Western Australia was a period of terrigenous clastic and abundant, unusual, biosiliceous sponge sedimentation. The Pallinup Formation (revised) consists of five units; 1 and 2 are basal sandstones, 3 and 4 are variably spiculitic mudstones, whilst the uppermost unit is spiculite and spongolite, and formalised as the Fitzgerald Member (new). The Pallinup Formation, plus coeval spiculites in palaeovalleys and carbonates in the western Eucla Basin, accumulated during one large‐scale, transgressive‐regressive relative sea‐level cycle. Drowned, low‐gradient rivers supplied mud but little sand. Instead, sand was locally sourced via transgressive shoreface erosion of deeply weathered regolith. Regression terminated shoreface erosion, eliminated the sand source, and resulted in a river‐supplied, clay‐dominated shallow‐marine depositional system. The unit 2–3 sandstone‐mudstone transition, which would normally be interpreted as transgressive drowning, is in this case the result of regressive cessation of sand supply. The peak relative sea‐level (highstand) horizon thus lies within unit 2 sandstones, a facies that would usually be considered wholly transgressive, and no highstand systems tract was deposited. The maximum flooding and downlap surfaces are the same horizon and cap the transgressive systems tract. They formed coincidentally or subsequent to peak relative sea‐level, but prior to initiation of unit 3 mudstone deposition. Upper unit 2 plus unit 3 represent a condensed section systems tract, and unit 4 plus the Fitzgerald Member comprise a regressive systems tract. 相似文献
19.
Investigation of the Upper Carboniferous to Lower Permian sedimentary strata of central Spitsbergen shows that this highly cyclic rock succession is composed of four long-term transgressive–regressive cycles. These long-term cycles are themselves composed of stacked higher order cycles. Transgressive phases are characterized by increasing accommodation space, and include a basal transgressive part of marked retrogradation of facies belts and thickening-upward component cycles. Regressive phases are characterized by decreasing accommodation space, displayed by progradation of facies belts, overall shallowing and increased restriction of the depositional environment, influx of coarse terrigenous sediments and increasing evidence of exposure and/or non-deposition. The oldest transgressive–regressive sequence identified, Sequence 1, is of Serpukhovian to Bashkirian age and represents a syn-rift sequence. Also composed of syn-rift sediments is the transgressive–regressive Moscovian to mid-Gzhelian-aged Sequence 2. The late Gzhelian to late Asselian Sequence 3 is mainly a post-rift sequence. The youngest sequence, Sequence 4, is of Sakmarian to possible Artinskian age, and is also composed of post-rift sediments. The individual transgressive–regressive cycles are defined as second-order cycles, based on lithological signatures, lateral extent of bounding unconformities, and the actual time period the cycles span. Local tectonic activity is believed to control to some extent the development of short-term cycles in the syn-rift succession. However, cyclicity within the long-term cycles is mainly controlled by eustatic sea-level fluctuations, and therefore enables them to be correlated to other Circum-Arctic regions. Copyright © 1999 John Wiley & Sons, Ltd. 相似文献
20.
Sequence stratigraphical analysis was applied to the Upper Carboniferous–Lower Permian sedimentary succession of the northeastern Ordos Basin, north China based on data acquired from ten entire logging curves and eight outcrops. The facies framework of the lithostratigraphical unit, the Taiyuan Formation comprises seven facies in two facies associations, varying from fluvio-delta to shelf-barrier islands. The facies are presented within a chronostratigraphical framework, linked by systems tract, which in turn are limited by flooding surfaces and sequence boundaries. Six third-order depositional sequences are recognised, bounded by six type 2 unconformities. An upwards-shallowing epicontinental sea sedimentary model is created, which consists of a sandstone, coal seam and carbonate succession. 相似文献