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1.
Luca Basilone 《Central European Journal of Geosciences》2009,1(3):251-273
Sequence stratigraphic studies of the Triassic through Paleogene carbonate successions of platform, slope and basin in western Sicily (Palermo and Termini Imerese Mountains) have identified a sedimentary cyclicity mostly caused by relative oscillations of sea level. The stratigraphic successions of the Imerese and Panormide palaeogeographic domains of the southern Tethyan continental margin were studied with physical-stratigraphy and facies analysis to reconstruct the sedimentary evolution of this platform-to-basin system. The Imerese Basin is characterized by a carbonate and siliceous-calcareous succession, 1200–1400m thick, Late Triassic to Eocene in age. The strata display a typical example of a carbonate platform margin, characterized by resedimented facies with progradational stacking patterns. The Panormide Carbonate Platform is characterized by a carbonate succession, 1000–1200 m thick, Late Triassic to Late Eocene, mostly consisting of shallow-water facies with periodic subaerial exposure. The cyclic arrangement has been obtained by the study of the stratigraphic signatures (unconformities, facies sequences, erosional surfaces and stratal geometries) found in the slope successions. The recognized pattern has been compared with coeval facies of the shelf. This correlation provided evidence of sedimentary evolution, influenced by progradation and backstepping of the shelf deposits. The stratigraphic architecture of the platform-to-basin system is characterized by four major transgressive/regressive cycles during the late Triassic to late Eocene. These cycles, framed in a chronostratigraphic chart, allows the correlation of the investigated shelf-to-basin system with the geological evolution of the African continental margin during the Mesozoic, showing tectono-eustatic cycles. The first cycle, encompassing the late Triassic to early Jurassic, appears to be related to the late syn-rift stage of the continental margin evolution. The following three cycles, spanning from the Jurassic to Eocene, can be related to the post-rift evolution and to thermal subsidence changes. 相似文献
2.
The 600 m thick prograding sedimentary succession of Wagad ranging in age from Callovian to Early Kimmeridgian has been divided
into three formations namely, Washtawa, Kanthkot and Gamdau. Present study is confined to younger part of the Washtawa Formation
and early part of the Kanthkot Formation exposed around Kanthkot, Washtawa, Chitrod and Rapar. The depositional architecture
and sedimentation processes of these deposits have been studied applying sequence stratigraphic context.
Facies studies have led to identification of five upward stacking facies associations (A, B, C, D, and E) which reflect that
deposition was controlled by one single transgressive — regressive cycle. The transgressive deposit is characterized by fining
and thinning upward succession of facies consisting of two facies associations: (1) Association A: medium — to coarse-grained
calcareous sandstone — mudrocks alternations (2) Association B: fine-grained calcareous sandstone — mudrocks alternations.
The top of this association marks maximum flooding surface as identified by bioturbational fabrics and abundance of deep marine
fauna (ammonites). Association A is interpreted as high energy transgressive deposit deposited during relative sea level rise.
Whereas, facies association B indicates its deposition in low energy marine environment deposited during stand-still period
with low supply of sediments. Regressive sedimentary package has been divided into three facies associations consisting of:
(1) Association C: gypsiferous mudstone-siltstone/fine sandstone (2) Association D: laminated, medium-grained sandstone —
siltstone (3) Association E: well laminated (coarse and fine mode) sandstone interbedded with coarse grained sandstone with
trough cross stratification. Regressive succession of facies association C, D and E is interpreted as wave dominated shoreface,
foreshore to backshore and dune environment respectively.
Sequence stratigraphic concepts have been applied to subdivide these deposits into two genetic sequences: (i) the lower carbonate
dominated (25 m) transgressive deposits (TST) include facies association A and B and the upper thick (75m) regressive deposits
(HST) include facies association C, D and E. The two sequences are separated by maximum flooding surface (MFS) identified
by sudden shift in facies association from B to C. The transgressive facies association A and B represent the sediments deposited
during the syn-rift climax followed by regressive sediments comprising association C, D and E deposited during late syn-rift
stage. 相似文献
3.
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
4.
O. P. Korsakova V. V. Kolka A. N. Tolstobrova N. B. Lavrova D. S. Tolstobrov T. S. Shelekhova 《Stratigraphy and Geological Correlation》2016,24(3):294-312
The complex lithological, geochemical, geochronological, and micropaleontological (diatoms, spores, pollen) investigations of stratified bottom sediments that constitute facies-variable sedimentary sequences in a small isolated lake located near the upper limit of the sea on the White Sea coast made it possible to define lithostratigraphic units (LSU) forming the complete sedimentary succession in deep parts of isolated basins. It is shown that stratigraphy of heterogeneous sequences is determined by two regional transgressive–regressive cycles in relative sea level fluctuations: alternating late Glacial and Holocene transgressions and regressions. The lower part of a clastogenic clayey–sandy–silty sequence successively composed of freshwater (LSU 1) and brackish-water (LSU 2) sediments of the ice-marginal basins and marine postglacial facies (LSU 3) was formed during the late Glacial glacioeustatic marine transgression. Its upper part formed in different isolated basins at different stages of the Holocene is represented depending on its altimetric position on the coastal slope by costal marine sediments (LSU 4) and facies of the partly isolated inlet (LSU 5). The organogenic sapropelic sequence, which overlies sediments of the marine basin and partly isolated bay, corresponds to lithostratigraphic units represented by Holocene sediments accumulated in the meromictic lake (LSU 6), onshore freshwater basin (LSU 7), and freshwater basin with elevated water mineralization (LSU 8) deposited during maximum development of Holocene transgression and lacustrine sediments (LSU 9) formed in coastal environments during terminal phases of the Holocene. The defined lithostratigraphic units differ from each other in lithological, micropaleontological, and geochemical features reflected in structural and textural properties of their sediments, their composition, inclusions, and composition of paleophytocoenoses and diatom assemblages. 相似文献
5.
《Cretaceous Research》2002,23(3):409-438
Four transgressive-regressive (T-R) cycles and five T-R subcycles have been recognized in Lower Cretaceous strata of the northeastern Gulf of Mexico. These T-R cycles are the LKEGR-TR 1 (Lower Cretaceous, Eastern Gulf Region) (upper Valanginian–upper Aptian), the LKEGR-TR 2 (upper Aptian–middle Albian), the LKEGR-TR 3 (middle–upper Albian), and the LKEGR-TR 4 (upper Albian–lower Cenomanian) cycles. The LKEGR-TR 1 Cycle consists of three subcycles: LKEGR-TR 1–1 (upper Valanginian–lower Aptian), LKEGR-TR 1–2 (lower Aptian) and LKEGR-TR 1–3 (upper Aptian) subcycles. The LKEGR-TR 2–1 (upper Aptian–lower Albian) and the LKEGR-TR 2–2 (lower–middle Albian) subcycles constitute the LKEGR-TR 2 Cycle. The LKEGR-TR 3 and the LKEGR-TR 4 cycles consist of a single T-R cycle.Recognition of these T-R cycles is based upon stratal geometries, nature of cycle boundaries, facies stacking patterns within cycles, and large-scale shifts in major facies belts. The T-R subcycles are characterized by shifts in major facies belts that are not of the magnitude of a T-R cycle. The cycle boundary may be marked by a subaerial unconformity, ravinement surface, transgressive surface or surface of maximum regression. A single T-R cycle consists of an upward-deepening event (transgressive aggrading and backstepping phases) and an upward-shallowing event (regressive infilling phase). These events are separated by a surface of maximum transgression. The aggrading phase marks the change from base-level fall and erosion to base-level rise and sediment accumulation; this phase signals the initiation of the creation of shelf-accommodation space. The marine transgressive and flooding events of the backstepping phase are widespread and provide regional correlation datums. Therefore, these T-R cycles and subcycles can be identified, mapped, and correlated in the northeastern Gulf of Mexico area. The progradational events associated with the regressive infilling phase represent a major influx of siliciclastic sediments into the basin, the development of major reef build-ups at the shelf margin, and a significant loss of shelf-accommodation space. These T-R cycles are interpreted to be the result of the amount of and change in shelf-accommodation due to a combination of post-rift tectonics, loading subsidence, variations in siliciclastic sediment supply and dispersal systems, carbonate productivity and eustasy associated with a passive continental margin. The T-R cycles, where integrated with biostratigraphic data, can be correlated throughout the northern Gulf of Mexico region and have the potential for global correlation of Lower Cretaceous strata. 相似文献
6.
H. D. SINCLAIR 《Sedimentology》1993,40(5):955-978
High resolution stratigraphical analysis divides a rock succession into the basic genetic units of stratigraphy which are here termed small scale stratigraphical cycles. Each cycle records the sedimentological response to an episode of shallowing and deepening. Assuming that these changes in water depth reflect changes in the shoreline position, they can be considered as regressive/transgressive episodes. Each cycle comprises a regressive and transgressive facies tract which will be variably proportioned; in some examples a facies tract may only be represented by a hiatal surface of no deposition, erosion and/or bypass. In the Annot Sandstones of south-east France, variations in facies types, proportions and associations can be demonstrated both laterally and vertically through the succession. First, it is demonstrated that facies variations occur within regressive or transgressive facies tracts as a function of the stratigraphical stacking pattern of the cycles (i.e. landward, vertical or seaward stacked); this is termed ‘vertical facies differentiation’. Second, the proportions of facies tracts and their constituent facies types within an individual cycle vary between more landward and more seaward palaeogeographical locations; this is termed ‘lateral facies differentiation'. The upper Eocene/lower Oligocene Annot sandstones outcrop in the Maritime Alps of south-east France, within the thin skinned outer fold and thrust belt of the Alpine arc. The sandstones are well exposed in the area of the Col de la Cayolle on the north-west margin of the Argentera Massif, where lithostratigraphical correlations are possible over 3·5 km in a NNW/SSE direction, perpendicular to the edge of the depositional basin. Traditionally, these outcrops have been interpreted as deep marine turbidite lobe sediments; this study reflects a significant reinterpretation of this succession as having been deposited in a shallow marine environment. Seven sedimentary sections were measured through the succession, which is divided into 10 small scale stratigraphical cycles. These cycles are described in terms of eight facies which are separated into their transgressive or regressive facies tracts. In eight of the 10 cycles, the regressive facies tracts reflect the progradation of storm influenced braid deltas over shelf muds and silts. In two of the 10 cycles, the regressive facies tracts reflect barrier inlet and wash-over sands interfingering with back barrier deposits. These latter two cycles are located within landward stepping cycle sets; this is an example of vertical facies differentiation. Transgressive facies tracts locally reworked the upper surface of the regressive facies tract and also comprise barrier and back barrier deposits. The facies succession within each cycle varies according to its position with respect to the palaeoshoreline. The more landward portion of an individual cycle comprises a deltaic shoaling upward succession, culminating in coarse distributary channel conglomerates, overlain by a transgressive barrier/inlet system with extensive back barrier deposits. Beyond the delta front, the more seaward equivalent of individual cycles comprises an erosive base, with aggradational massive pebbly sandstones sitting directly upon offshore heterolithics; these sandstones are interpreted as hyperconcentrated fluvial efflux into the nearshore environment. This grades upward into offshore heterolithics and graded storm deposits representing the products of ravinement, which are then overlain by shelf mudstones. In summary, the more landward portions of cycles preserve predominantly regressive facies tracts, whereas the more seaward portions preserve aggradational to retrogradational strata of the transgressive facies tract; this is an example of lateral facies differentiation. 相似文献
7.
During the early Middle Devonian in South China, an extensive carbonate platform was broken up through extension to create a complex pattern of platforms, and interplatform basins. In Givetian and Frasnian carbonate successions, five depositional facies, including peritidal, restricted shallow subtidal, semi‐restricted subtidal, intermediate subtidal and deep subtidal facies, and 18 lithofacies units are recognized from measured sections on three isolated platforms. These deposits are arranged into metre‐scale, upward‐shallowing peritidal and subtidal cycles. Nine third‐order sequences are identified from changes in cycle stacking patterns, vertical facies changes and the stratigraphic distribution of subaerial exposure indicators. These sequences mostly consist of a lower transgressive part and an upper regressive part. Transgressive packages are dominated by thicker‐than‐average subtidal cycles, and regressive packages by thinner‐than‐average peritidal cycles. Sequence boundaries are transitional zones composed of stacked, high‐frequency, thinner‐than‐average cycles with upward‐increasing intensity of subaerial exposure, rather than individual, laterally traceable surfaces. These sequences can be further grouped into catch‐up and keep‐up sequence sets from the long‐term (second‐order) changes in accommodation and vertical facies changes. Catch‐up sequences are characterized by relatively thick cycle packages with a high percentage of intermediate to shallow subtidal facies, and even deep subtidal facies locally within some individual sequences, recording long‐term accommodation gain. Keep‐up sequences are characterized by relatively thin cycle packages with a high percentage of peritidal facies within sequences, recording long‐term accommodation loss. Correlation of long‐term accommodation changes expressed by Fischer plots reveals that during the late Givetian to early Frasnian increased accommodation loss on platforms coincided with increased accommodation gain in interplatform basins. This suggests that movement on faults resulted in the relative uplift of platforms and subsidence of interplatform basins. In the early Frasnian, extensive siliceous deposits in most interplatform basins and megabreccias at basin margins correspond to exposure disconformities on platforms. 相似文献
8.
Syn-rift shallow-marine carbonates of Late Aptian to Early Albian age in the southern Maestrat Basin (E Spain) register the thickest Aptian sedimentary record of the basin, and one of the most complete carbonate successions of this age reported in the northern Tethyan margin. The host limestones (Benassal Formation) are partially replaced by dolostones providing a new case study of fault-controlled hydrothermal dolomitization. The syn-rift sediments filled a graben controlled by normal basement faults. The Benassal Fm was deposited in a carbonate ramp with scarce siliciclastic input. The lithofacies are mainly characterized by the presence of orbitolinid foraminifera, corals and rudist bivalves fauna. The succession is stacked in three transgressive–regressive sequences (T–R) bounded by surfaces with sequence stratigraphic significance. The third sequence, which is reported for the first time in the basin, is formed by fully marine lithofacies of Albian age and represents the marine equivalent to the continental deposits of the Escucha Fm in the rest of the basin.The dolomitization of the host rock is spatially associated with the basement faults, and thus is fault-controlled. The dolostone forms seismic-scale stratabound tabular geobodies that extend several kilometres away from the fault zones, mostly in the hanging wall blocks, and host Mississippi Valley Type (MVT) deposits. The dolostones preferentially replaced middle to inner ramp grain-dominated facies from the third T–R sequences consisting of bioclastic packestones and peloidal grainstones. Field and petrology data indicate that the replacement took place after early calcite cementation and compaction, most likely during the Late Cretaceous post-rift stage of the basin. The dolostone registers the typical hydrothermal paragenesis constituted by the host limestone replacement, dolomite cementation and sulfide MVT mineralization. The Aptian succession studied provides a stratigraphic framework that can be used for oil exploration in age-equivalent rocks, especially in the València Trough, offshore Spain. Moreover, this new case study constitutes a world class outcrop analogue for similar partially stratabound, dolomitized limestone reservoirs worldwide. 相似文献
9.
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
10.
Middle Tithonian-Berriasian shallow platform carbonates of the Maestrat Basin (Salzedella and Montanejos sections, NE Spain) are stacked in sequence stratigraphic units of different orders. Higher-order sequences (parasequences and subunits) have a shallowing or deepening-shallowing evolution. They have been related to the short-term eccentricity and precession cycles. Major facies changes and stacking pattern of parasequences reveal the presence of two 2nd-order sequences. The Lower Sequence is middle Tithonian-mid early Berriasian in age. The Upper Sequence extends up to the mid-late Berriasian. It is suggested that local subsidence changes along with regional sea-level changes controlled the long-term evolution of accommodation in the Maestrat Basin. Facies evolution, stacking pattern and sharp lithological changes have allowed the definition of five 3rd-order sequences in the Lower Sequence in Montanejos. The transgressive deposits are characterised by the progressive absence of the restricted lagoon facies, and the presence of deepening-upward intervals in the parasequences. The highstand deposits display an increase in siliciclastics and a progressive predominance of restricted lagoon facies. Some of the 3rd-order sequence boundaries match the sequence boundaries identified in other European basins and may be related to sea-level falls (induced by the long-term eccentricity cycle) enhanced during periods of long-term loss of accommodation. 相似文献
11.
A siliciclastic-dominated succession (～11 m thick) underlying Harrat Rahat, belonging to the Miocene–Pliocene Bathan Formation is recently exposed at Al-Rehaili area, North Jeddah, Saudi Arabia. It covers a wide spectrum of grain sizes varying from clay-rich mudstones to cobble grade conglomerate and consists of a variety of facies vary from fluvial to marginal and open lacustrine deposited in a half-graben basin formed along the eastern margin of the extensional Red Sea Basin. Field-based sedimentologic investigation enables to identify ten facies grouped into three facies associations (A–C). The depositional history is subdivided into two stages. The first stage represents deposition in gravel to sand-dominated fluvial system sourced from a southern source and grade northward into lacustrine delta and open lacustrine setting. The second stage on the other hand includes deposition of fluvial channels running in E–W direction with attached bank sand bar. Sequence stratigraphic interpretations of the lacustrine deposits enable to identify three unconformity-bounded sequences (SQ1–3). The basal sequence is incomplete, consisting of three aggradationally to progradationally stacked delta plain and delta front parasequences. The second sequence is sharply and erosively overlying a red paleosol bed that defines the upper boundary of the first sequence. It includes two system tracts; upward-fining and deepening lacustrine offshore mudstones of the transgressive system tracts unconformably overlain by red paleosol of the regressive systems tracts. The top of this sequence is delineated at the sharp transgressive surface of erosion at the base of delta mouth bar deposits of sequence 3. Changes in the accommodation and sedimentation rates by basin subsidence under the influence of tectonics and sediment compaction and loading as well as climatic oscillation between semi-arid to arid conditions were the major controls on the fluvio-lacustrine sedimentation and their facies distribution. Tectonic reorganization of the drainage system resulted in the formation of E–W flowing fluvial streams in the second stage. 相似文献
12.
Biplab Bhattacharya Joyeeta Bhattacharjee Sandip Bandyopadhyay Sudipto Banerjee Kalyan Adhikari 《Journal of Earth System Science》2018,127(2):29
The present research is an attempt to assess the Barakar Formation of the Raniganj Gondwana Basin, India, in the frame of fluvio-marine (estuarine) depositional systems using sequence stratigraphic elements. Analysis of predominant facies associations signify deposition in three sub-environments: (i) a river-dominated bay-head delta zone in the inner estuary, with transition from braided fluvial channels (FA-B1) to tide-affected meandering fluvial channels and flood plains (FA-B2) in the basal part of the succession; (ii) a mixed energy central basin zone, which consists of transitional fluvio-tidal channels (FA-B2), tidal flats, associated with tidal channels and bars (FA-B3) in the middle-upper part of the succession; and (iii) a wave-dominated outer estuary (coastal) zone (FA-B4 with FA-B3) in the upper part of the succession. Stacked progradational (P1, P2)–retrogradational (R1, R2) successions attest to one major base level fluctuation, leading to distinct transgressive–regressive (T–R) cycles with development of initial falling stage systems tract (FSST), followed by lowstand systems tract (LST) and successive transgressive systems tracts (TST-1 and TST-2). Shift in the depositional regime from regressive to transgressive estuarine system in the early Permian Barakar Formation is attributed to change in accommodation space caused by mutual interactions of (i) base level fluctuations in response to climatic amelioration and (ii) basinal tectonisms (exhumation/sagging) related to post-glacial isostatic adjustments in the riftogenic Gondwana basins. 相似文献
13.
The Erlian Basin is one of the non-marine Cretaceous basins of north-east China that developed during the late Mesozoic continental extension in eastern Asia. This basin experienced two major tectonic events: (i) a syn-rift stage that was dominated by a fluvial–lacustrine depositional environment and (ii) a post-rift stage that was dominated by a fluvial environment. A new sedimentological study performed on Erlian Formation drill cores has led to the determination of an architectural model and to the subsequent characterisation of the stratigraphic evolution of this sedimentary unit during the late Cretaceous. The palynological occurrences that were identified in samples provided a possible stratigraphical age for the Erlian Formation.Sediments of the Erlian Formation occur at the top of the Cretaceous stratigraphic column of the Erlian Basin and were deposited during the post-rift stage. Facies architecture and the ideal succession of facies that were identified for this formation exhibit two different members, both dominated by a fluvial depositional environment: (i) the lower member, which is dominated by channels of a braided river system and (ii) the upper member, which is dominated by overbank deposits. The lower member expresses a tectonically induced uplift as indicated by channels clustering under negative accommodation, whereas a period of stratigraphic base-level rise that is associated with an increase of accommodation is identified in the upper member. Therefore the Erlian Formation highlights an alternation of short uplifts that were dominated by braided fluvial channel deposits with periods of stratigraphic base-level rise that were dominated by overbank deposits. This sedimentological architecture has significant metallogenic implications for the origin of confined permeable sandstone layers, which represent adequate host-rocks for roll front-type uranium deposits.The palynological assemblage Exesipollenites, Ulmipollenites/Ulmoideipites, Buttinia and Momipites that were recognised in two samples of the Erlian Formation has revealed a post-late Campanian age therefore more likely indicating a late Cretaceous age of deposition for the sediments of the Erlian Formation. 相似文献
14.
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
15.
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
16.
《International Geology Review》2012,54(10):866-892
The stratigraphic and structural evolution of the Pattani Basin, the most prolific petroleum basin in Thailand, reflects the extensional tectonic regime of continental Southeast Asia. E-W extension resulting from the northward collision of India with Eurasia since the Early Tertiary resulted in the formation of a series of N-S-trending sedimentary basins, which include the Pattani Basin. The sedimentary succession in the Pattani Basin is divisible into synrift and post-rift sequences. Deposition of the synrift sequence accompanied rifting and extension, with episodic block faulting and rapid subsidence. The synrift sequence comprises three stratigraphic units: (1) Upper Eocene to Lower Oligocene alluvial-fan, braidedriver, and floodplain deposits; (2) Upper Oligocene to Lower Miocene floodplain and channel deposits; and (3) a Lower Miocene regressive package consisting of marine to nonmarine sediments. Post-rift succession comprises: (1) a Lower to Middle Miocene regressive package of shallow marine sediments through floodplain and channel deposits; (2) an upper Lower Miocene transgressive sequence; and (3) an Upper Miocene to Pleistocene transgressive succession. The post-rift phase is characterized by slower subsidence and decreased sediment influx. The present-day shallow-marine condition in the Gulf of Thailand is the continuation of this latest transgressive phase. The subsidence and thermal history of the Pattani Basin is consistent with a nonuniform lithospheric-stretching model. The amount of extension as well as surface heat flow generally increases from the margin to the basin center. The crustal stretching factor (β) varies from 1.3 at the basin margin to 2.8 in the center. The subcrustal stretching factor (5) ranges from 1.3 at the basin margin to more than 3.0 in the basin center. The stretching of the lithosphere may have extended the basement rocks by as much as 45 to 90 km and has led to passive upwelling of the aesthenosphere, resulting in high heat flow (1.9 to 2.5 Heat Flow Units [HFU]) and high geothermal gradient (45 to 60° C/km). The validity of nonuniform lithospheric stretching as a mechanism for the formation of the Pattani Basin is confirmed by the good agreement between the level of organic maturation modeled on the basis of the predicted heatflow history and measured vitrinite reflectance at various depths measured in some 30 boreholes. 相似文献
17.
《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
18.
贵州南部的泥盆系为一个大型的楔状体。从深水背景的广西南丹罗富剖面到古陆边缘的贵阳乌当剖面,泥盆系由13个层序变薄尖灭成5个层序,这是泥盆纪早期海侵尖灭与晚期海退尖灭的结果。研究区泥盆系由海侵碎屑岩岩系到清水台地碳酸盐岩岩系地层序列构成2个二级层序,又可进一步划分为13个三级层序。二级层序和三级层序均由其特殊的沉积相序列组成。研究区泥盆系层序地层划分和层序地层格架的建立提供了一个在年代地层与海平面变化框架内研究“相迁移”的良好实例。 相似文献
19.
应用800多口钻孔及文献资料,讨论了中国沿海滦河扇三角洲、长江三角洲和珠江三角洲及钱塘江河口湾4个地区的下切河谷体系,这些皆为丰沙河流形成的河口三角洲。这些河口三角洲地区的下切河谷为长形或扇形,长数十至数百千米,宽数十千米,深40～90 m。河口三角洲地区的下切河谷相序可分为4种类型,即FS-Ⅰ,FS-Ⅱ,FS-Ⅲ和FS-Ⅵ。可以将这4类相序自海向陆排成一个理想序列：FS-Ⅰ位于海岸线附近,FS-Ⅳ位于河口三角洲的顶部,显示海的影响逐渐减弱,陆相作用逐渐增强。下切河谷层序可分为海侵和海退序列。海侵序列的厚度占下切河谷层序的50％以上,体积占60％～70％。海侵序列是在海平面上升过程中,溯源堆积依次叠置而成的,其下部的河床相是在溯源堆积能到达、而涨潮流未能到达的下游河段产生的,往往不含海相微体化石和潮汐沉积构造。在海侵序列中未见区域上可对比的侵蚀面,表明冰后期海平面上升速率的变化、甚至小幅下降也未留下统一的侵蚀记录。下切河谷中的海退序列由河口湾充填及三角洲进积而成,其进程是各不相同的：长江古河口湾先被强潮河口湾相、后由三角洲相所充填,河口湾也经历了由强潮型向中潮型的转变;滦河扇三角洲和珠江三角洲,其古河口湾则被河流相和三角洲相所充填;钱塘江河口湾正被强潮河口湾相所充填。 相似文献
20.
N. A. Azerbaev 《Lithology and Mineral Resources》2001,36(1):13-22
The lithofacial study of Vendian–Lower Paleozoic sedimentary sequences of the Greater Karatau and Baikonur synclinorium, which are the constituents of the Ishim–Karatau lithostructural zone, revealed that Vendian, Cambrian, and Ordovician rocks form a continuous succession composing the Caledonian cyclic unit. In duration (220–240 Ma), the latter corresponds to a megacycle. The cyclic unit consists of the transgressive and regressive parts. The upper part of the transgressive succession includes facies of the continental slope, slope foot, near-continental area, and transitional zone between the near-continental and pelagic areas of the abyssal plain. It is shown that an avalanche sedimentation of the second global level occurred twice during the transgressive and regressive phases. The formation of transgressive facies was related to the extension regime during the basin opening, whereas regressive facies accumulated under the compression regime. The Ishim–Karatau zone is located in the western, outer part of Caledoninian structures in Kazakhstan. The Caledonian cyclic unit formed on the Vendian–Early Paleozoic Atlantic-type margin of the Kazakhstan microcontinent. Specific features of the cyclic development of mobile areas are outlined. 相似文献