scholarly journals A forced regressive shelf-margin wedge formed by transition-slope progradation: lowermost Cretaceous Rauk Plateau Member, Jameson Land, East Greenland

2005 ◽  
Vol 52 ◽  
pp. 227-243 ◽  
Author(s):  
F. Surlyk
Keyword(s):  
Sea Level ◽  
Large Scale ◽  
Coarse Grained ◽  
Shelf Edge ◽  
High Angle ◽  
Seismic Profiles ◽  
East Greenland ◽  
Shelf Slope ◽  
Forced Regression ◽  
Shelf Margin

The Middle Jurassic – lowermost Cretaceous succession of Jameson Land, East Greenland records a marine, overall regressive–transgressive–regressive cycle with regressive maxima in the Late Bajocian and Late Volgian separated by a transgressive maximum in the Kimmeridgian. Smaller-scale regressive interludes took place in the Late Callovian and Mid Oxfordian. A shelf-slope-basin physiography started to develop in the Late Callovian due to increasing rifting and a relief of several hundred metres was attained during maximum end-Jurassic regression and deposition of the Volgian Raukelv Formation. The formation consists of a forestepping stack of laterally extensive shelf-edge wedges, each several tens of metres thick, composed of coarse-grained sandstone, showing highangle clinoform bedding and containing marine body and trace fossils. These clinoform beds are superimposed on the large-scale clinoforms of the shelf–slope–basin. The wedges onlap older shelf deposits in a landward direction and are overlain by thin transgressive sandstones or mudstones, or directly by the next coarse-grained wedge. The top wedge, comprising the Rauk Plateau Member, is of Late Volgian (i.e. earliest Cretaceous) age and is characterized by steep clinoforms truncated by internal erosional downlap surfaces. The clinoforms are simple avalanche beds, a few tens of centimetres thick, or they may be several metres thick and contain large-scale cross-bedded intrasets of probable tidal origin. The erosional events were associated with downshift of the succeeding clinoforms, recording minor sea-level fall and forced regression. The top surface of the Rauk Plateau wedge is incised by a system of minor channels leading to a large canyon-like valley. The wedge was deposited by transition-slope progradation below wave base during a period of sea-level stillstand punctuated by minor, stepwise falls. It provides an excellently exposed example of a laterally derived, coarse-grained shelf-margin wedge, showing high-angle clinoform bedding and representing an ancient counterpart to Holocene and Late Pleistocene prograding infralittoral wedges seen on seismic profiles across Mediterranean shelf edges.

The arrival of the paleo–Orinoco Delta at Trinidad: The Cruse Formation delta lobes and delivery to deepwater Atlantic

2020 ◽  
Vol 90 (8) ◽  
pp. 938-968
Author(s):  
Ariana Osman ◽  
Ronald J. Steel ◽  
Ryan Ramsook ◽  
Cornel Olariu ◽  
Si Chen
Keyword(s):  
Sea Level ◽  
Late Miocene ◽  
Sediment Supply ◽  
Average Height ◽  
Shelf Edge ◽  
Sea Level Changes ◽  
Orinoco Delta ◽  
Basin Floor ◽  
Shelf Margin ◽  
High Sediment

ABSTRACT Icehouse continental-shelf-margin accretion is typically driven by high-sediment-supply deltas and repeated glacio-eustatic, climate-driven sea-level changes on a ca. 100 ky time scale. The paleo–Orinoco margin is no exception to this, as the paleo–Orinoco River Delta with its high sediment load prograded across Venezuela, then into the Southern and Columbus basins of Trinidad since the late Miocene, depositing a continental-margin sedimentary prism that is > 12 km thick, 200 km wide, and 500 km along dip. The Cruse Formation (> 800 m thick; 3 My duration) records the first arrival of the paleo–Orinoco Delta into the Trinidad area. It then accreted eastwards, outwards onto the Atlantic margin, by shallow to deepwater clinoform increments since the late Miocene and is capped by a major, thick flooding interval (the Lower Forest Clay). Previous research has provided an understanding of the paleo–Orinoco Delta depositional system at seismic and outcrop scales, but a clinoform framework detailing proximal to distal reaches through the main fairway of the Southern Basin has never been built. We integrate data from 58 wells and outcrop observations to present a 3-D illustration of 15 mapped Cruse clinoforms, in order to understand the changing character of the first Orinoco clastic wedge on Trinidad. The clinoforms have an undecompacted average height of 550 m, estimated continental slope of 2.5° tapering to 1°, and a distance from shelf edge to near-base of slope of > 10 km. The clinoform framework shows trajectory changes from strong shelf-margin progradation (C10–C13) to aggradation (C14–C20) and to renewed progradation (C21–24). Cruse margin progradational phases illustrate oblique clinothem geometries that lack well-developed topsets but contain up to 70 m (200 ft) thick, deepwater slope channels. This suggests a high supply of sediment during periods of repeated icehouse rise and fall of eustatic sea level, with fall outpacing subsidence rates at times, and delivery of sand to the deepwater region of the embryonic Columbus channel region. Also, evidence of wholesale shelf-edge collapse and canyon features seen in outcrop strongly suggest that deepwater conduits for sediment dispersal and bypass surfaces for Cruse basin-floor fans do exist. The change to a topset aggradational pattern with a rising shelf trajectory may be linked to increased subsidence associated with eastward migration of the Caribbean plate. The Cruse-margin topsets were dominated by mixed fluvial–wave delta lobes that were effective in delivery of sands to the basin floor. The preservation of a fluvial regime of the delta may have been impacted by basin geometry which partly sheltered the area from the open Atlantic wave energy at the shelf edge. Ultimately, understanding shelf-edge migration style as well as process-regime changes during cross-shelf transits of the delta will help to predict the location of bypassed sands and their delivery to deepwater areas.

Temporary late Holocene barrier-chain deterioration due to insufficient sediment availability, Wadden Sea, Denmark

Geology ◽  
2020 ◽  
Author(s):  
Mikkel Fruergaard ◽  
Lasse Sander ◽  
Jérôme Goslin ◽  
Thorbjørn J. Andersen
Keyword(s):  
Sea Level ◽  
Large Scale ◽  
Wadden Sea ◽  
Sediment Cores ◽  
Regional Scale ◽  
Barrier Islands ◽  
Seismic Profiles ◽  
Littoral Drift ◽  
Data Set ◽  
Coastal Barrier

Understanding the coupling between sediment availability and sea-level change is important for forecasting coastal-barrier (barrier islands and barrier spits) response to future sea-level rise (SLR). An extensive data set of sediment cores, seismic profiles, and a high-resolution chronology from the Wadden Sea (southeastern North Sea) documents that long-term barrier-chain progradation was interrupted by a period of widespread barrier deterioration between ca. 3.5 and 2.0 ka. The decay of the barrier islands resulted from a decrease in littoral drift triggered by regional-scale coastal reconfiguration. The formation of a large cuspate foreland updrift caused the depositional locus to shift away from the barrier coast. Our results demonstrate that the resulting reduction in marine sediment availability substantially decreased the stability of the barrier chain, causing the regional SLR thresholds to fall from between 2 and 9 mm yr–1 to ~0.9 mm yr–1, and thus below contemporary rates of SLR. Hence, we argue that predicting the response of barrier coasts to ongoing SLR requires consideration of possible changes in sediment availability and the role of large-scale geomorphological feedbacks due to human and natural causes.

scholarly journals Shallow marine syn-rift sedimentation: Middle Jurassic Pelion Formation, Jameson Land, East Greenland

2003 ◽  
Vol 1 ◽  
pp. 813-863 ◽  
Author(s):  
Michael Engkilde ◽  
Finn Surlyk
Keyword(s):  
Sea Level ◽  
Middle Jurassic ◽  
Large Scale ◽  
Significant Shift ◽  
Shallow Marine ◽  
East Greenland ◽  
Upper Bajocian ◽  
Stacking Pattern ◽  
Facies Associations ◽  
Middle Callovian

The Middle Jurassic Pelion Formation – Fossilbjerget Formation couplet of Jameson Land, East Greenland, is a well-exposed example of the Middle Jurassic inshore–offshore successions characteristic of the rifted seaways in the Northwest European – North Atlantic region. Early Jurassic deposition took place under relatively quiet tectonic conditions following Late Permian – earliest Triassic and Early Triassic rift phases and the Lower Jurassic stratal package shows an overall layer-cake geometry. A long-term extensional phase was initiated in Middle Jurassic (Late Bajocian) time, culminated in the Late Jurassic (Kimmeridgian–Volgian), and petered out in the earliest Cretaceous (Valanginian). The Upper Bajocian – Middle Callovian early-rift succession comprises shallow marine sandstones of the Pelion Formation and correlative offshore siltstones of the Fossilbjerget Formation. Deposition was initiated by southwards progradation of shallow marine sands of the Pelion Formation in the Late Bajocian followed by major backstepping in Bathonian–Callovian times and drowning of the sandy depositional system in the Middle–Late Callovian. Six facies associations are recognised in the Pelion–Fossilbjerget couplet, representing estuarine, shoreface, offshore transition zone and offshore environments. The north–southtrending axis of the Jameson Land Basin had a low inclination, and deposition was sensitive to even small changes in relative sea level which caused the shorelines to advance or retreat over tens to several hundreds of kilometres. Eight composite sequences, termed P1–P8, are recognised and are subdivided into a total of 28 depositional sequences. The duration of the two orders of sequences was about 1–2 Ma and 360,000 years, respectively. The Upper Bajocian P1–2 sequences include the most basinally positioned shallow marine sandstones, deposited during major sealevel lowstands. The lowstands were terminated by significant marine flooding events, during which sandstone deposition was restricted to northern, more proximal parts of the basin. The Upper Bajocian – Middle Bathonian P3–4 sequences show an overall progradational stacking pattern. The sequence boundary at the top of P4 marks a significant shift in stacking pattern, and the Upper Bathonian – Middle Callovian P5–8 sequences show large-scale backstepping, terminating in a widespread condensed succession at the distal, southern end of the basin. The largescale backstepping was governed by combined tectonically-induced subsidence, reflecting increased rates of extension, and eustatic sea-level rise. The depositional trends of the Pelion Formation – Fossilbjerget Formation couplet provide a well-exposed analogue to contemporaneous subsurface deposits which form major hydrocarbon reservoirs on the west Norway shelf, and in the Northern North Sea.

Nass River on the move: radar facies analysis of glaciofluvial sedimentation and its response to sea-level change in northwestern British Columbia

2006 ◽  
Vol 43 (11) ◽  
pp. 1733-1746 ◽  
Author(s):  
S J McCuaig ◽  
M C Roberts
Keyword(s):  
British Columbia ◽  
Sea Level ◽  
Facies Analysis ◽  
Late Glacial ◽  
Depositional Environments ◽  
Coarse Grained ◽  
Sea Levels ◽  
Stratal Architecture ◽  
Forced Regression ◽  
Radar Facies

The Nass Valley of northwestern British Columbia is a glacial fiord containing extensive glaciomarine and glaciofluvial sediments. Two parallel braidplains, separated by a bedrock ridge, were deposited within the fiord. Mapping of these deposits led to the hypothesis that the braidplains must have terminated at deltas. However, a lack of surface exposures meant that ground-penetrating radar was needed to investigate these deposits. Radar facies analysis aided in the identification of braidplain, braid delta and glaciomarine depositional environments, as well as underlying bedrock. Several deltas graded to different sea levels were discovered, allowing inferences to be made about the relationship of falling sea level to sediment architecture. The upper section of the western braidplain is graded to a sea level of 185 m above sea level (asl), indicating that the proto-Nass River flowed on the western side of the bedrock ridge when the sea was at that level. However, the river moved to the east side of the ridge as sea level fell, depositing the extensive Aiyansh Braidplain – Braid Delta, which is graded to a 152 m sea-level stand. Several other deltas also formed at this sea-level stand. Avulsion occurred and the river flowed on the west side of the ridge again when sea level fell to 134 m asl. The river remained in this position throughout late glacial time and eventually evolved into the modern Nass River. The coarse-grained deposits are indicative of forced regression, with both stepped-top attached and detached stratal architecture present.

scholarly journals Submarine fan sedimentation along fault scarps on tilted fault blocks (Jurassic-Cretaceous boundary, East Greenland)

1978 ◽  
Vol 128 ◽  
pp. 1-108
Author(s):  
F Surlyk
Keyword(s):  
Large Scale ◽  
Sediment Supply ◽  
Coarse Grained ◽  
East Greenland ◽  
Submarine Fans ◽  
Clastic Sediments ◽  
Sediment Gravity Flow ◽  
Facies Associations ◽  
The One ◽  
Fault Scarps

In late Jurassic times large-scale faulting, which partly occurred along old lines of weakness, fragmented the East Greenland shelf into several westerly tilted blocks. The sediments of the syntectonic Middle Volgian-Valanginian Wollaston Forland Group were deposited along and away from the fault scarps formed at the uptilted western margin of each block. To the west the group comprises thick syntectonic clastic wedges of submarine rock-fall breccias which pass laterally into thick conglomerates and sandstones deposited by various types of sediment gravity flow. Further to the east these facies pass rapidly into mudstones. The depositional regime was characterized by repeated fault activity resulting in deepening of the depositional basins, followed by rapid erosion of borderlands and sedimentation of very coarse clastic sediments on a narrow coastal fringe of fan-deltas leading into submarine fans. This pattern continued into Ryazanian time (early Lower Cretaceous), and in the Valanginian a major regional transgression initiated an open shelf where light grey mudstones and sandstone turbidites were deposited. These Middle Volgian to Valanginian sediments are interpreted as showing a progressively collapsing and submerging platform. The model presented for submarine sedimentation along fault scarps on tilted fault blocks displays the same facies associations as the one for deep-sea fans. Distinguishing characters are seen in the intern al distribution of facies. The sediment prism is arranged in several hundred metres thick fining-upward megacycles corresponding to major phases of faulting and down-tilting of fault blocks. They also indicate gradually diminishing sediment supply following rapid erosion and retreat of borderlands. Megacycles are internally composed of fining-upward cycles a few metres to tens of metres thick. These cycles reflect progressive tilling and abandonment of inner and midfan channels. The very coarse-grained proximal units wedge out very rapidly in a distal direction where the seaward dipping fan slope is checked due to the dip slope of the opposite fault block.

scholarly journals Estimation of the Effect of Eddies on Coastal El Niño Flows Using Along-Track Satellite Altimeter Data

2013 ◽  
Vol 43 (6) ◽  
pp. 1209-1224 ◽  
Author(s):  
Emma M. Giunipero ◽  
Allan J. Clarke
Keyword(s):  
Sea Level ◽  
El Niño ◽  
Time Scale ◽  
Large Scale ◽  
El Nino ◽  
Altimeter Data ◽  
Western Coast ◽  
Shelf Edge ◽  
Shelf Sea ◽  
Along Track

Abstract Previous work has shown that the El Niño sea level signal leaks through the gappy western equatorial Pacific to the coasts of western and southern Australia. South of about 22°S, in the region of the Leeuwin Current, the amplitude of this El Niño signal falls. Using coastal sea level measurements and along-track altimetry data from the Ocean Topography Experiment (TOPEX)/Poseidon, Jason-1, and OSTM/Jason-2 satellites, this study finds that the interannual divergence of the eddy momentum flux D′ is correlated with the southward along-shelf sea level amplitude decay, consistent with the eddies removing energy from the large-scale sea level signal. The quantity D′ is also correlated with the interannual flow with a surprisingly short dissipation time scale of only 2 days, much shorter than the interannual time scale. A similar analysis off the western coast of South America, site of the originally named “El Niño” current, was carried out. Interannual sea level decay along the shelf edge is observed, and the interannual southward flow along the shelf edge is found to be highly positively correlated with the along-shelf sea level decay with a dissipation time scale of a few days. Dynamics similar to the Australian case likely apply.

scholarly journals Peneplains and tectonics in North-East Greenland after opening of the North-East Atlantic

2021 ◽  
Vol 45 (1) ◽  
Author(s):  
Johan M. Bonow ◽  
Peter Japsen
Keyword(s):  
Sea Level ◽  
Large Scale ◽  
Continental Margins ◽  
Rift Basins ◽  
East Greenland ◽  
Planation Surface ◽  
Base Level ◽  
North East ◽  
The North ◽  
Late Neogene

Elevated plateaus with deeply incised valleys characterise elevated, passive continental margins (EPCMs) in all climate zones. These features are, however, a topic of debate regarding when and how the large-scale landscapes formed. We have investigated and mapped the partly glaciated landscape of North-East Greenland (70–78°N). The area consists of crystalline basement and Palaeozoic–Mesozoic rift basins, capped by Palaeogene basalts that erupted during the northeast Atlantic break-up. Our stratigraphic landscape analysis reveals a typical EPCM dominated by two elevated erosion surfaces, extending 200 km east–west and 900 km north–south. The low-relief Upper Planation Surface (UPS; c. 2 km above sea level) cuts across basement and Palaeogene basalts, indicating that it was graded to base level defined by the Atlantic Ocean in post-basalt times and subsequently uplifted. The UPS formed prior to the deposition of mid-Miocene lavas that rest on it, south of the study area. In the interior basement terrains, the Lower Planation Surface (LPS) forms fluvial valley benches at c. 1 km above sea level, incised below the UPS. The LPS is thus younger than the UPS, which implies that it formed post mid-Miocene. Towards the coast, the valley benches merge to form a coherent surface that defines flat-topped mountains. This shows that the LPS was graded to near sea level and was subsequently uplifted. Hence, both the UPS and the LPS formed as peneplains – erosion surfaces graded to base level. The fluvial valley benches associated with the LPS further indicates that full glacial conditions were only established after the uplift of the LPS in the early Pliocene (c. 5 Ma). The uplift of the LPS led to re-exposure of a Mesozoic etch surface. We conclude that episodes of late Neogene tectonic uplift shaped the stepped landscape and elevated topography in North-East Greenland.

scholarly journals Stratigraphy of the marine Lower Triassic succession at Kap Stosch, Hold with Hope, North-East Greenland

2017 ◽  
Vol 65 ◽  
pp. 87-123
Author(s):  
Finn Surlyk ◽  
Morten Bjerager ◽  
Stefan Piasecki ◽  
Lars Stemmerik
Keyword(s):  
Arctic Region ◽  
Lower Triassic ◽  
Coarse Grained ◽  
The Arctic ◽  
Delta Front ◽  
East Greenland ◽  
Fine Grained ◽  
North East ◽  
The North ◽  
Shelf Slope

The classical marine uppermost Permian – Lower Triassic succession exposed on the north-east coast of Hold with Hope in East Greenland, south-east of Kap Stosch, is placed in the Wordie Creek Group. A new lithostratigraphic subdivision of the group is proposed here. The group comprises the revised Kap Stosch Formation overlain by the new Godthåb Golf Formation. The Kap Stosch Formation is dominated by alternating fine- and coarse-grained, cliff-forming units that constitute the basis for the erection of eight new members. They are (from below): 1. The Nebalopok Member, uppermost Permian, Hypophiceras triviale ammonoid zone, and lowermost Triassic, lower Griesbachian, Hypophiceras triviale – H. martini ammonoid zones, composed of basinal and base-of-slope siltstones and turbiditic sandstones. 2. The conglomeratic Immaqa Member (H. martini ammonoid zone), consisting of a thick clinoform-bedded unit commonly overlain by horizontally bedded deposits, representing the foreset and topset, respectively, of a Gilbert-type delta. 3. The fine-grained Fiskeplateau Member (H. martini ammonoid zone), composed of siltstones and fine-grained sandstones, representing basinal and delta front deposits. 4. The conglomerate-dominated Knolden Member (H. martini ammonoid zone), comprising a clinoform-bedded unit overlain by horizontally-bedded deposits, representing foreset and topset, respectively, of a Gilbert-type delta. 5. The fine-grained Pyramiden Member, (lower–upper Griesbachian Metophiceras subdemissum, Ophiceras commune and Wordieoceras decipiens ammonoid zones), composed of variegated siltstones and sandstones deposited in proximal basin and slope environments. 6. The Naasut Member (top Griesbachian, probably Wordieoceras decipiens ammonoid zone), dominated by thick structureless coarse-grained sandstones commonly showing clinoform bedding, deposited in slope, base-of-slope and proximal basin environments. 7. The Falkeryg Member (lowermost Dienerian, Bukkenites rosenkrantzi ammonoid zone), comprising thick, commonly pebbly sandstones deposited in shelf, slope and base-of-slope environments. 8. The Vestplateau Member (lower Dienerian, Bukkenites rosenkrantzi ammonoid zone) composed of siltstones and fine-grained sandstones deposited in basinal environments. The overlying Godthåb Golf Formation (Dienerian, Anodontophora breviformis – A. fassaensis bivalve zones) is dominated by shallow marine sandstones with several coarser grained levels. The rich ammonoid faunas of the Wordie Creek Group allow a biostratigraphic zonation which can be correlated with schemes from other parts of the Arctic region. This zonation is complemented with information on palyno, conodont, fish and isotope stratigraphy.

scholarly journals Late Jurassic evolution of the Jameson Land Basin, East Greenland – implications of the Blokelv-1 borehole

2018 ◽  
pp. 149-168
Author(s):  
Morten Bjerager ◽  
Peter Alsen ◽  
Jørgen A. Bojesen-Koefoed ◽  
Tove Nielsen ◽  
Stefan Piasecki ◽  
...  
Keyword(s):  
Sea Level ◽  
Field Studies ◽  
Upper Jurassic ◽  
Shelf Edge ◽  
Block Rotation ◽  
Sea Level Changes ◽  
Relative Sea Level ◽  
East Greenland ◽  
Half Graben ◽  
Basin Floor

Data from the recently drilled, fully cored Blokelv-1 borehole and previous cored boreholes in the Upper Jurassic of Jameson Land, central East Greenland, are integrated with published field studies to address the depositional evolution of the Jameson Land Basin in the Oxfordian–Volgian. In Jameson Land, the succession represents a marine shelf-to-basin transect in a W–SW-dipping half-graben. Laminated organic-rich mudstones were deposited in the central deep parts of the basin and grade up-slope into bioturbated sandy mudstones. Extensive shallow marine – deltaic sand prograded from the western and northern basin margins and formed prominent sandy shelf-edge wedges. Sand-rich density flows initiated by periodic collapse of the shelf edge deposited massive sand bodies on the slope and basin floor; these sands were prone to post-burial remobilisation to form injectite bodies. Basin evolution was controlled both by relative sea-level changes, typically correlatable with regional and global sea-level curves, and by rift tectonics. During periods with high relative sea level, the organicrich muddy facies onlapped the sandy shelf environments; such periods of basinal expansion and onlap are recorded in the lower Oxfordian (Q. mariae Chronozone), the middle–upper Oxfordian (C. tenuiserratum – A. glosense Chronozones) and uppermost Oxfordian – upper Kimmeridgian (A. regulare – A. autissiodorensis Chronozones); the deepening, transgressive trend culminated in the mid-Kimmeridgian (A. eudoxus Chron). Marked progradation of the sandy shelf and associated deposition of gravity-flow sands on the slope and basin floor occurred in the early Oxfordian (C. cordatum Chron), the middle Oxfordian (C. densiplicatum Chron), the late Oxfordian (A. serratum Chron) and the early Volgian (P. elegans Chron). The basin architecture reflects periodic differential subsidence on the W- to SW-dipping fault block. The lower to middle Oxfordian is highly condensed in the east (<10 m) and thickens markedly towards the west (>300 m), reflecting accumulation during rift/fault-controlled block rotation. The upper Oxfordian – Kimmeridgian, in contrast, shows a broadly symmetrical distribution and records uniform regional subsidence.

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