Shelf construction in a foreland basin: storm beds, shelf sandbodies, and shelf-slope depositional sequences in the Upper Cretaceous Mesaverde Group, Book Cliffs, Utah

The Upper Cretaceous (Campanian) Kenilworth Member of the Blackhawk Formation (Mesaverde Group) is part of a series of strand plain sandstones that intertongue with and overstep the shelfal shales of the western interior basin of North America. Analysis of this section at a combination of small (sedimentological) and large (stratigraphical) scales reveals the dynamics of progradation of a shelf-slope sequence into a subsiding foreland basin. Four major lithofacies are present in the upper Mancos and Kenilworth beds of the Book Cliffs. A lag sandstone and channel-fill shale lithofacies constitutes the thin, basal, transgressive sequence, which rests on a marine erosion surface. It was deposited in an outer shelf environment. Shale, interbedded sandstone and shale, and amalgamated sandstone lithofacies were deposited over the transgressive lag sandstone lithofacies as a wave-dominated delta and its flanking strand plains prograded seaward. Analysis of grain size and primary structures in Kenilworth beds indicates that there are four basic strata types which combine to build the observed lithofacies. The fine- to very fine-grained graded strata of the interbedded facies are tempestites, deposited out of suspension by alongshelf storm flows (geostrophic flows). There is no need to call on cross-shelf turbidity currents (density underflows) to explain their presence. Very fine- to fine-grained hummocky strata are likewise suspension deposits created by waning storm flows, but were deposited under conditions of more intense wave agitation on the middle shoreface. Cross-strata sets in this region are bed-load deposits that accumulated on the upper shore-face, in the surf zone. Lag strata are multi-event, bed-load deposits that are the product of prolonged storm winnowing. They occur on transgressive surfaces. While the graded beds are tempestites in the strict sense, all four classes of strata are storm deposits. The distribution of strata types and their palaeocurrent orientations suggests a model of the Kenilworth transport system driven by downwelling coastal storm flows, and probably by a northeasterly alongshore pressure gradient. The stratification patterns shift systematically from upper shoreface to lower shoreface and inner shelf lithofacies partly because of a reduction in fluid power expenditure with increasing water depth, but also because of progressive sorting, which resulted in a decrease in grain size in the sediment load delivered to successive downstream environments. The Kenilworth Member and an isolated outlier, the Hatch Mesa lentil, constitute a delta-prodelta shelf depositional system. Their rhythmically bedded, lenticular, sandstone and shale successions are a prodelta shelf facies, and may be prodelta plume deposits. Major Upper Cretaceous sandstone tongues in the Book Cliffs are underlain by erosional surfaces like that beneath the Blackhawk Formation, which extend for many tens of kilometres into the Mancos shale. These surfaces are the boundaries of Upper Cretaceous depositional sequences. The sequences are large-scale genetic stratigraphic units. They result from the arranging of facies into depositional systems; the depositional systems are in turn stacked in repeating arrays, which constitute the depositional sequences. The anatomy of these foreland basin sequences differs     

Signatures of storms, oceanic floods and forearc tectonism in marine shelf strata of the Quinault Formation (Pliocene), Washington, USA

Marine shelf strata of the Quinault Formation reflect the influences of storm–flood processes and convergent margin tectonism on sedimentation and palaeocommunity distributions in an active forearc basin of Early Pliocene age, western Washington, USA. The sedimentologic, ichnologic and invertebrate megafaunal character of coastal sea cliff exposures in the Pratt Cliff–Duck Creek area, Quinault Indian Nation, reveal five different sedimentary facies – scoured, Rosselia, bioturbated, mixed and Acharax. These facies document the shifting interplay and intensities among storms, waves and river‐flood plumes during transgression in inner to mid‐shelf settings. Storm sedimentation on the inner shelf is recorded north of Pratt Cliff by amalgamated, proximal tempestites of the scoured facies, which grade up‐section to thick deposits of hummocky cross‐stratified sandstone, indicative of strong wave influences. These hummocky beds alternate, in metre‐scale packages, with banded mudstone and siltstone that have distinctive sedimentologic and ichnofaunal characteristics (Rosselia facies). In particular the mudstone and siltstone occur as 1–15 cm‐thick, rhythmic, parallel beds that are laterally continuous, internally homogeneous to faintly laminated, and thus similar in nature to fine‐grained, oceanic flood deposits reported from shelf settings offshore the modern Eel River, northern California. The Quinault flood deposits are dominated by the ubiquitous trace fossil Rosselia socialis, comprising vertical, mud‐packed, flaring burrows with a sand‐filled central shaft which has been inferred as the feeding‐dwelling structure of a vermiform invertebrate adapted to high sedimentation rates in inner‐shelf settings. Fairweather conditions in between the higher energy periods of storms, waves and floods are recorded north of Pratt Cliff by the mixed facies, which is interpreted as representing the sand and mud zone of the inner‐ to mid‐shelf transition. Quieter, deeper, mid‐shelf, fairweather settings are typified by the bioturbated facies south of Pratt Cliff, where lower sedimentation rates and lower physical energies produced extensively bioturbated deposits of sandy siltstone punctuated, in places, by isolated sandy beds of distal tempestites. Quinault strata also chronicle stratigraphic signatures of subduction of the Juan de Fuca plate beneath western Washington during the Pliocene. For example, the imprint of geochemically unusual authigenic carbonates and a chemosynthetic palaeocommunity (Acharax facies) have been interpreted as a methane seep on the Quinault seafloor. Furthermore, a mobile rockground epifauna of pholadid bivalves became established on abundant, dark mudstone cobbles and pebbles sourced from the Hoh Assemblage, a Miocene accretionary prism that was actively deforming as well as interacting with Quinault forearc sediments during the Pliocene. Hoh mudstone clasts were supplied to the Quinault shelf via seafloor‐piercing diapirs and eroding mélange shear zones, exposures of which today occur in fault contact with Quinault strata along the coast from Taholah to the Raft River.     

张家界地区中晚寒武世岩相古地理特征

张家界地区中晚寒武世岩相带3分格局明显，自NW向SE依次为台地相、台缘斜坡相和陆棚相。3相区之间分别以花坦－张家界、古丈－张家界深大断裂为界。台地相欧孔王溪组属邻近盆缘陡坡地带类似于深水陆棚沉积，重力沉积发育；娄山关组北西小区记录了由台地边缘浅滩→局限台地潮坪→台地边缘浅滩的变迁过程；而东南小区则属台地边缘与斜坡的过渡地带。台缘斜坡相区敖溪组反映了缓慢的海退过程，沉积环境由陆棚向陆棚内缘带变迁；车夫组属台地前缘斜坡带，重力沉积转化为蚀流沉积；比条组为背景沉积综合产物，反映了台地前缘斜坡上带环境，陆棚相区探溪组旋回性明显。反映了陆棚内缘沉积特点；田家坪属台缘斜坡下带－陆棚内缘环境，沉积了一套多具鲍玛层序的远源风暴岩。各自有其岩石类型组合特征及沉积构造特征，并讨论了岩相古地一的演化规律。     

Palaeoenvironments, palaeogeography, and physiography of a large, shallow, muddy ramp: Late Cenomanian-Turonian Kaskapau Formation, Western Canada foreland basin

The Kaskapau Formation spans Late Cenomanian to Middle Turonian time and was deposited on a low‐gradient, shallow, storm‐dominated muddy ramp. Dense well log control, coupled with exposure on both proximal and distal margins of the basin allows mapping of sedimentary facies over about 35 000 km². The studied portion of the Kaskapau Formation is a mudstone‐dominated wedge that thins from 700 m in the proximal foredeep to 50 m near the forebulge about 300 km distant. Regional flooding surfaces permit mapping of 28 allomembers, each of which represent an average of ca 125 kyr. More than 200 km from shore, calcareous silty claystone predominates, whereas 100 to 200 km offshore, mudstone and siltstone predominate. From about 30 to 100 km offshore, centimetre‐bedded very fine sandstone and mudstone record along‐shelf (SSE)‐directed storm‐generated geostrophic flows. Five to thirty kilometres from shore, decimetre‐bedded hummocky cross‐stratified fine sandstone and mudstone record strongly oscillatory, wave‐dominated flows whereas some gutter casts indicate shore‐oblique, apparently mostly unidirectional geostrophic flows. Nearshore facies are dominated by swaley cross‐stratified or intensely bioturbated clean fine sandstone, interpreted as recording, respectively, areas strongly and weakly affected by discharge from distributary mouths. Shoreface sandstones grade locally into river‐mouth conglomerates and sandstones, including conglomerate channel‐fills up to 15 m thick. Locally, brackish lagoonal shelly mudstones are present on the extreme western margin of the basin. There is no evidence for clinoform stratification, which indicates that the Kaskapau sea floor had extremely low relief, lacked a shelf‐slope break, and was probably nowhere more than a few tens of metres deep. The absence of clinoforms probably indicates a long‐term balance between rates of accommodation and sediment supply. Mud is interpreted to have been transported >250 km offshore in a sea‐bed nepheloid layer, repeatedly re‐suspended by storms. Fine‐grained sediment accumulated up to a ‘mud accommodation envelope’, perhaps only 20 to 40 m deep. Continuous re‐working of the sea floor by storms ensured that excess sediment was redistributed away from areas that had filled to the ‘accommodation envelope’, being deposited in areas of higher accommodation further down the transport path. The facies distributions and stratal geometry of the Kaskapau shelf strongly suggest that sedimentary facies, especially grain‐size, were related to distance from shore, not to water depth. As a result, the ‘100 to >300 m’ depth interpreted from calcareous claystone facies for the more central parts of the Interior Seaway, might be a significant overestimate.     

Biostratigraphy, depositional environments, and diagenesis of the Tamana Formation, Trinidad: a tectonic marker horizon

The Tamana Formation of the Central Range of Trinidad was studied in order to determine its importance in the stratigraphical and structural development of north-eastern South America. Biostratigraphical, petrological and mineralogical data, combined with field mapping show that the Tamana sediments are composed of five distinct lithofacies: inner to outer shelf, burrowed shaley mudstone; outer shelf, Fe-rich sandy limestone; submarine channel, conglomeratic mudstone; middle shelf to nearshore, algal-foram packstone/grainstone; and intertidal to nearshore, algal-stromatolite-coral boundstone with coral bioherms. Maximum thickness of the Tamana Formation is 244 m. Deposition of the Tamana limestones occurred between the Praeorbulina glomerosa (latest early Miocene) and Globorotalia fohsi robusta (middle part of the middle Miocene) planktonic foraminiferal zones, and in a more continuous trend than is seen in the current outcrop belt. Detailed biostratigraphy shows that the Tamana Formation is a facies equivalent of the shallow- and deep-water shales of the Brasso Formation, and the deep water turbidites of the Herrera Member of the Cipero Formation. The early diagenetic history of the Tamana limestones was dominated by the precipitation of authigenic glauconitic smectite, and the dissolution of skeletal grains and carbonate matrix. Late burial diagenesis was dominated by the precipitation of illite and illite/smectite. Comparative mineralogy and textural analyses indicate a minimum range of burial depth for the Tamana Formation at 800–1500m, with a maximum of 2400 m. Alteration of Fe-bearing minerals to geothite and late fracturing occurred during post-Pliocene tectonic uplift and unroofing of the Central Range. The Tamana Formation sediments can be used as a structural and stratigraphical event marker within the Late Tertiary geological history of Trinidad. These units record a phase of the tectonic interaction between the Caribbean and South American plates in the south-eastern Caribbean, and reflect the onset of contractile deformation in the Central Range.     

Lithofacies, taphonomy, and brachiopod assemblages in the Silurian of western Argentina: A review of Malvinokaffric Realm communities

Distribution of faunal associations in the Silurian sequences of the Precordilleran and Northwestern Basins of Argentina is integrated with sedimentologic and taphonomic data, demonstrating that marked temporal and spatial changes in the Malvinokaffric brachiopod assemblages are related mainly to the type and intensity of the hydraulic regime of the shelf environment. The vertical arrangement of associations within each basin is controlled by local fluctuations in water depth, whereas the spatial variations are linked to minor environmental changes (substrate type and oxygen content). The basal strata of the Middle-Upper Silurian Los Espejos Formation of the Precordilleran Basin are mudstones of an open-shelf environment. These pass upward into facies of a storm-dominated shelf and shoreface. Four brachiopod assemblages have been recognized in the muddy facies: the Harringtonina Low-Diversity and Australina-Dominated associations characterize distal storm beds; the Harringtonina High-Diversity and Coelospira-Dominated communities occur in the fine-grained rocks of proximal tempestites. Storm shell beds, which dominate the middle-upper part of the sequence, are represented by allochthonous and parautochthonous coquinas. The Clarkeia Association flourished in shallow-water, high-energy, nearshore environments. Silurian rocks in the Northwestern Basin were deposited in an offshore, low-energy, restricted environment, and two main faunal assemblages have been recognized: a more distal Heterorthella Association and a relatively more proximal Ancillotoechia Association.     

Upper Cretaceous Gongila Formation in the Hawal Basin, northeast Benue Trough: a storm and wave dominated regressive shoreline complex

The Gongila Formation in the Hawal Basin displays lithological characteristics, textural variations and sedimentary structures that facilitate palaeoenvironmental reconstruction. The 41 m thick Gongila succession is divisible into: (i) a mudstone facies association (at the bottom) composed of fossiliferous limestone, clay shale, and sharp-based, graded and swaly-bedded shell debris; and (ii) a cross-stratified sandstone facies association that constitutes the uppermost 60% of the entire succession. The cross-stratified sandstone facies association is further subdivided, on the basis of sedimentary structures, into: (i) a lower interval represented by a coarsening upward fine- to medium-grained sandstone, siltstone and shale in which units characterised by parallel lamination and hummocky cross-stratification pass upward through a zone of small-scale low angle cross-stratification into units characterised by planar cross-stratification and sparse Teichichnus and Skolithos burrow traces; and (ii) an upper interval dominated by fine- to medium-grained sandstone and bioturbated siltstone characterised by erosive based, high angle tangential foresets, subhorizontal laminations and burrow structures belonging to the Thalassinoides, Ophiomorpha and Skolithos ichnogenera.The overall sequence of the Gongila Formation represents progradation on a wave influenced coast, passing from shelf mudstone at the base to lower and upper shoreface sandstones at the top. Each facies association displays an alternation between relatively high energy conditions when sediment was mainly deposited by decelerating suspension laden currents, and relatively low energy conditions when wave reworked fine-grained sediment as it was deposited from suspension. The influence of storms in these conditions is inferred from the associated lithofacies, textural characteristics and sedimentary structures.     

Eastern Mississippi delta: late Wisconsin unconformity, overlying transgressive facies, sea level and subsidence

Analysis of 92 engineering core logs located in the Balize sector of the eastern Mississippi delta focuses on the late Wisconsin unconformity and lithofacies of strata lying immediately below and above this stratigraphic horizon. This major sequence boundary is a key feature used to correlate strata across shelf and slope to the basin. Observations emphasize lithofacies distributions of the latest Pleistocene sediments underlying the unconformity, the late Pleistocene to early Holocene transgressive facies, and the immediately overlying deltaic deposits. Maps and a cross-section compiled with this information highlight the critical relation between lithofacies distributions and late Wisconsin sea-level oscillations. Core analysis reveals that the transgressive facies comprises distinct environments of deposition, offshore to onshore. Findings identify criteria to determine the approximate position of the shoreline at the late Wisconsin maximum sea-level lowstand and at the extent of early Holocene maximum marine inundation in the Balize complex. Mapping of lithologies along the late Wisconsin unconformity serves to improve correlation of sediment facies with changes in acoustic response along high-resolution seismic profiles. An estimate of long-term averaged land subsidence suggests lowering of at least 1 mm/year near the shelfedge during the past 18 000 years. This mapping also refines sea-level response models for the Mississippi delta, including criteria to locate key paleogeographic features such as shelfedges and maximum flooding surfaces in other Recent marine deltas and in older, stacked deltaic sequences.     

Mid-cycle condensed shellbeds from mid-Pleistocene cyclothems, New Zealand: implications for sequence architecture

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.     

Plio‐Pleistocene tectonics and eustasy in the Gippsland Basin,southeast Australia: Evidence from magnetic imagery and marine geological data

The Pliocene and Pleistocene sediments of the Gippsland shelf are dominated by mixed carbonates and siliciclastics. From a detailed stratigraphic study that combines conventional marine geology techniques with magnetic imagery, the Late Neogene tectonic and eustatic history can be interpreted and correlated to the onshore section. Stratigraphic analyses of eight oil and gasfield foundation bores drilled to 150 m below the seabed revealed three principal facies types: (i) Facies A is fine‐grained limestone and limey marl deeper than 50 m below the seabed, of Late Pliocene age (nannofossil zones CN11–12); (ii) Facies B is a fine‐coarse pebble quartz‐carbonate sand that occurs 10–50 m below the seabed in the inner shelf, grading down into Facies A in wells in the outer shelf, and is of Early‐Middle Pleistocene age (nannofossil subzones CN13a-14b: ca 1.95–0.26 Ma); and (iii) discontinuous horizons of Facies C composed of carbonate‐poor carbonaceous and micaceous fine quartz sand occurring 10–50 m below the seabed. The sparse benthic foraminifers in Facies C are inner shelf or Gippsland (euryhaline) Lakes forms. Holocene sands dominate the upper 1.5–2.5 m of the Gippsland shelf and disconformably overlie cemented limestones with aragonite dissolution, indicating previous exposure to meteoric water. Nannofossil dating of the limestones indicates ages within subzone CN14b (dated between ca 0.26 and 0.47 Ma). Airborne magnetic imaging across the Gippsland shelf and onshore provides details of buried magnetic palaeoriver channels and barrier systems. The river systems trend south‐southeast from the Snowy, Tambo, Mitchell, Avon, Macalister and Latrobe Rivers across the shelf. Sparker seismic surveys show the magnetic palaeochannels as seismic ‘smudges’ 20–40 m below the seabed. They appear to correspond to Facies C lenses (i.e. are Early to Middle Pleistocene features). Magnetic palaeobarrier systems trending south‐southwest in the inner shelf and onshore beneath the Gippsland Lakes are orientated 15° different to the modern Ninety Mile Beach barrier trend. Offshore, they correlate stratigraphically to progradation packages of Facies B. Analysis of bore data in the adjacent onshore Gippsland Lakes suggests that a Pliocene barrier sequence 100–120 m below surface is overlain by fluvial sand‐gravel and lacustrine mud facies. The ferruginous sandstone beds resemble offshore Facies C, and are located where magnetic palaeoriver channel systems occur, implying Early to Middle Pleistocene ages. Presence of the estuarine bivalve Anadara trapezia in the upper lacustrine mud facies suggests that the Gippsland Lakes/Ninety Mile Beach‐type barriers developed over the past 0.2 million years. Further inland, magnetic river channels that cut across present‐day uplifted structures, such as the Baragwanath Anticline, suggest that onshore Gippsland uplift continued into the Middle Pleistocene.     

Paucispecific macroinvertebrate communities in the Upper Cretaceous of El Hassana Dome (Abu Roash,Egypt): Environmental controls vs adaptive strategies

Based on rock and fossil data from the Upper Cretaceous of the El Hassana Dome (Abu Roash, Egypt), factors controlling facies architecture and the nature of biotopes are highlighted. The succession formed on a non-rimmed shelf, the architecture of which varied from an inner to an outer shelf setting upsection. Macrobenthic biotopes are reconstructed and their palaeoecological significance assessed using a novel ternary plot. Based on diversity and community structure (770 specimens assigned to 28 bivalve and gastropod taxa), four paucispecific associations are identified. These are: 1. the ‘Cucullaea’ Assemblage, a low-energy, soft-substrate, oligotrophic outer shelf environment with reduced terrigenous input dominated by infaunal bivalves and hexactinellid sponges; 2. the ‘Plicatula’ Assemblage, a low-energy, restricted inner shelf lagoonal setting with soupy substrates and dysoxia below the sediment-water interface dominated by plicatulid and ostreid bivalves, 3. the ‘Durania’ Assemblage, a high-energy, high-temperature, shoal environment dominated by elevator rudists with minor numbers of echinoids, corals and bryozoans, which together form several biostromes. and 4. The ‘Trochactaeon’ Assemblage, which share the same characteristics of the ‘Durania’ Assemblage. The paucispecific nature of these biotopes is indicative of different stress factors. Consequently, the predominant taxa exhibit different degrees of adaptive strategies. In addition to global sea level, local tectonics have significantly affected facies distribution and biotope structure. The shallower facies during the early Turonian and the dysoxia spanning the Coniacian–Santonian were linked to synsedimentary tectonics, which formed many barriers and led to circulation restrictions.     

Early Cretaceous ostracoda from the Goban Spur; D.S.D.P. leg 80, site 549

Site 549 recovered a Lower Cretaceous succession which has been shown to include parts of the Barremian and Albian stages. Forty-four species of Ostracoda are illustrated and their stratigraphic distribution used to recognise three major facies units. An high diversity inner shelf facies earlier in the Barremian gives way to a low diversity, outer shelf facies, higher in the succession. The early Albian appears to indicate a return to an inner shelf fauna. The faunas recovered have been compared to similar faunas elsewhere in N. W. Europe.     

Depositional framework and controls on mixed carbonate-siliciclastic gravity flows: Pennsylvanian-Permian shelf to basin transect, south-western Great Basin, USA

Mixed carbonate-siliciclastic sediment gravity flow deposits of Late Pennsylvanian to Early Permian age are exposed in the Death Valley - Owens Valley region of east-central California. The Mexican Spring unit constitutes the upper part of the Keeler Canyon Formation and is characterized by turbidites, debris flow deposits and megabreccias, all of mixed carbonate-siliciclastic composition. The mixed composition of the Keeler Canyon Formation provides an opportunity to link facies architecture to controls on depositional system development. Depositional relationships indicate that the deposits represent a non-channellized base of slope carbonate apron system with inner, outer and basinal facies associations. These gravity flow deposits are characterized by repeated stacked, small scale (<15 m) coarsening and thickening upward cycles with superimposed medium scale (>100 m) coarsening and thickening upward cycles. Contemporaneous outer shelf and upper slope deposits of the Tippipah Limestone are exposed at Syncline Ridge on the Nevada Test Site. The deposits consist of carbonate buildups directly overlain by cross bedded, quartz-rich sandstone and conglomerate which filled channels that traversed across the previously existing carbonate shelf. Detritus was transported to the west, down the upper slope by gully systems that fed the temporally persistent base of slope apron of the upper part of the Keeler Canyon Formation. This style of deposition differs from point-sourced siliciclastic submarine fan depositional systems. However, the Keeler Canyon system has lithofacies similar to some sandy siliciclastic turbidite systems, such as the delta-fed submarine ramp facies model, which is a line-sourced, shelf-fed system that is not supply limited. The mixed clastic apron systems of the Keeler Canyon Formation differ from classical carbonate aprons in that the former is characterized by an abundance of sedimentary cycles. Controls on the development of these cycles and of the facies distribution may have resulted from changes in type and rate of sediment supply, relative sea level changes and/or tectonic events. Interpretation of the data is focused on relative changes in sea level as the most significant control on development of the depositional system. Relative sea level changes serve two important functions: (1) they provide a mechanism for bringing coarse siliciclastic and bioclastic grains together on the outer shelf, and (2) shelf margin collapse may be initiated during relative lowstands allowing for transport of the sediment to the deep basin and development of deep basinal cycles. Therefore, an abundance of mixed clastic gravity flow deposits such as these in the rock record may be an indicator of periods of high frequency changes in relative sea level, which is a characteristic of Late Palaeozoic sea level history.     

湘鄂地区晚寒武世末至早奥陶世特马豆克期层序地层与岩相古地理

从寒武纪末至早奥陶世特马豆克期（牙形类Cordylodus intermedius 带至Serratognathus 带）,地处扬子陆块的湘鄂地区分为三个沉积区：浅水碳酸盐台地、台地东南缘碳酸盐岩、泥质岩混合沉积区和较深水细碎屑岩沉积区。前二个沉积区的层序地层分为4个正层序,在同一陆块内不同沉积区这四个三级层序相互可对比,代表了四次三级海侵、海退旋回。其中牙形类Paltodus deltifer 带中、下部是特马豆克期最大的海侵时期。特马豆克早期（Glyptoconus quadraplicatus 带）和晚期（Serratognathus带中、上部）分别发生过大的海退事件。各正层序的体系域岩相古地理格局能更客观地反映该地区特马豆克期古地理演化特征。特马豆克初期（C.lindstromi 带至C.angulatus带下部）自鄂西北至湘中地区依次为潮坪、潮间泻湖白云岩相、开阔碳酸盐台地、台地边缘浅滩、碳酸盐岩台地边缘斜坡、黑色碳质页岩盆地的古地理格局。特马豆克早期（Glyptoconus quadraplicatus 带）缓慢海退时期海水普遍变浅,自北向南依次为潮坪、潮间泻湖白云岩相、局限台地相、台地边缘浅滩相和较深水碳酸盐外陆架。特马豆克中期海进时期,生屑灰岩和页岩沉积向北超覆,扩展至青峰襄广断裂。湘鄂浅水碳酸盐沉积区为开阔碳酸盐台地,混合沉积区为较深水碳酸盐外陆架,湘中地区为深水泥质下外陆架。特马豆克晚期缓慢海退时期海水再度变浅,在湖北、湘西北开阔碳酸盐台地上,出现台内生屑浅滩、台地边缘生屑浅滩,浅滩上发育有海绵、苔藓虫礁丘。     

Microfacies analysis and cyclostratigraphy of the upper cretaceous- lower paleogene succession of Bir Dakhl section,north eastern desert,Egypt

The Bir Dakhl section which is located in the southern Galala plateau, north eastern desert was sampled for microfacies analysis of the upper Cretaceous–lower Paleogene succession. Microfacies analysis led to the recognition of eight mixed clastic-carbonate facies types (black shale lithofacies MF-1, pure shale lithofacies MF-2, sandy shale lithofacies MF-3, marly shale lithofacies MF-4, mudstone microfacies MF-5, foraminiferal wackestone microfacies MF-6, bioclastic wackestone microfacies MF-7, and bioclastic packstone microfacies MF-8) of the studied interval. These microfacies can be grouped into three depositional environments: inner, middle and outer ramp. The interpreted depositional environments have been suggested to range from neritic to middle bathyal (~ 700 m). Based on cyclostratigraphy, five deepening upward cycles and three shallowing upward cycles have been differentiated in Bir Dakhl section.     

Storm-dominated sedimentation along a rocky transgressive shoreline in the Silurian (Llandovery) of Western Ireland

Sedimentation patterns are described from the Kilbride Formation west of the Maam Fault zone, north Galway, Ireland. Seven distinct facies are described using faunal and lithological parameters. Environments of deposition range from marginal marine to deep shelf conditions. Lateral facies distributions were largely controlled by a rocky topographic high which influenced sedimentation until being buried by outer shelf sediments in middle-upper Kilbride Formation times. Four distinct sequences are described: in the lower Kilbride Formation, sequences I and IV are dominated by proximal storm deposits; sequence II was deposited in the lee of the topographic high and is interpreted as barred estuarine deposits; and in sequence III, at the topographic high, no deposition took place. In the upper Kilbride Formation the barrier was buried and uniform outer shelf conditions prevailed throughout the area. Faunal assemblages were strongly controlled by local environmental conditions and do not conform directly with the expected pattern of depth-related brachiopod communities. The Lingula and Eocoelia communities are amalgamated and alloch-thonous, the Pentameroides and Costistricklandia communities are absent, and only the Clorinda community is well represented, though parautochthonous.     

Late Pliocene to Holocene platform evolution in northern Belize, and comparison with coeval deposits in southern Belize and the Bahamas

Lithostratigraphy, depositional facies architecture, and diagenesis of upper Pliocene to Holocene carbonates in northern Belize are evaluated based on a ca 290 m, continuous section of samples from a well drilled on Ambergris Caye that can be linked directly to outcrops of Pleistocene limestone, and of overlying Holocene sediments. Upper Pliocene outer‐ramp deposits are overlain unconformably by Pleistocene and Holocene reef‐rimmed platforms devoid of lowstand siliciclastics. Tectonism controlled the location of the oldest Pleistocene platform margin and coralgal barrier reef, and periodically affected deposition in the Holocene. A shallow, flat‐topped, mostly aggradational platform was maintained in the Holocene by alternating periods of highstand barrier‐reef growth and lowstand karstification, differential subsidence, and the low magnitude of accommodation space increases during highstands. Facies in Pleistocene rocks to the lee of the barrier reef include: (i) outer‐shelf coralgal sands with scattered coral patch reefs; (ii) a shoal–water transition zone comprising nearshore skeletal and oolitic sands amidst scattered islands and tidal flats; and (iii) micritic inner‐shelf deposits. Four glacio‐eustatically forced sequences are recognized in the Pleistocene section, and component subtidal cycles probably include forced cycles and autocycles. Excluding oolites, Holocene facies are similar to those in the Pleistocene and include mud‐mounds, foraminiferal sand shoals in the inner shelf, and within the interiors of Ambergris and surrounding cayes, mangrove swamps, shallow lagoons, and tidal and sea‐marginal flats. Meteoric diagenesis of Pliocene and Pleistocene rocks is indicated by variable degrees of mineralogic stabilization, generally depleted whole‐rock δ¹⁸O and δ¹³C values, and meniscus and whisker‐crystal cements. Differences in the mineralogy and geochemistry of the Pliocene and Pleistocene rocks are attributed to variable extent of meteoric alteration. Dolomitization in the Pliocene carbonates may have begun syndepositionally and continued into the marine shallow‐burial environment. Positive dolomite δ¹⁸O and δ¹³C values suggest precipitation from circulating, near‐normal marine fluids that probably were modified somewhat by methanogenesis. Sedimentologic and diagenetic attributes of the Pliocene–Pleistocene rocks in the study area are similar to those in the Bahamas with which they share a common history of sea‐level fluctuations and climate change.     

http://www.sciencedirect.com/science/article/pii/S1674987111000600

Detailed studies on Late Devonian to Early Carboniferous carbonate rocks in central Hunan, southern China have led to the recognition of 25 lithofacies which can be grouped into:(1) inner ramp peritidal platform,(2) inner ramp organic bank and mound.(3) mid ramp,(4) outer ramp,and(5) shelf basin fades associations.The peritidal platform fades association dominates the Zimenqiao Formation (Namurian A or late Datangian) and is characterized by gypsum and dolostone-containing sequences, indicating a peritidal platform environment.The other four fades associations dominate the Menggongao Formation(late Famennian).Liujiatang Formation(Tournaisian or Yangruanian).Shidengzi Formations (early Visean or early Datangian).Five upward-shallowing cycles were distinguished in these three Formations.The predominant fades associations developed in each Formation demonstrate an overall transgression-regression cycle in the Late Devonian to Early Carboniferous in central Hunan.The overall transgressive sequence was preserved in the Shaodong.Menggongao.and Liujiatang Formations,and the overall regressive sequence was preserved in the Liujiatang.Shidengzi.Ceshui and Zimenqiao Formations.