Genetic sequence stratigraphy for the North Sea Late Jurassic and Early Cretaceous: distribution and prediction of Kimmeridgian–Late Ryazanian reservoirs in the North Sea and adjacent areas

1993 ◽  
Vol 4 (1) ◽  
pp. 347-370 ◽  
Author(s):  
M. A. PARTINGTON ◽  
B. C. MITCHENER ◽  
N. J. MILTON ◽  
A. J. FRASER
Keyword(s):  
Sequence Stratigraphy ◽  
North Sea ◽  
Early Cretaceous ◽  
Late Jurassic ◽  
Genetic Sequence ◽  
The North ◽  
The North Sea

scholarly journals Early Cretaceous

1982 ◽  
Vol 8 ◽  
pp. 45-49
Author(s):  
Jens Morgen Hansen ◽  
Arne Buch
Keyword(s):  
North Sea ◽  
Early Cretaceous ◽  
Late Cretaceous ◽  
Late Jurassic ◽  
Significant Feature ◽  
Marine Clay ◽  
The North ◽  
Marine Sand ◽  
The North Sea ◽  
Early Late

The Early Cretaceous sea primarily covered the same basinal regions as the Late Jurassic sea but, late in the Early Cretaceous the sea also covered Late Jurassic land masses. During Early Cretaceous time the topography of the North Sea region became gradually buried. The following major transgression comprises the transition Early/Late Cretaceous. At the Jurassic/ Cretaceous transition, the Late Cimmerian unconformity is a significant feature (fig. 24), known from large parts of the North Sea region. The subsequent transgression and sedimentation of marine clay (the Valhall Formation), and marine sand (the LC-1 Unit), started late in Late Jurassic. Therefore, the formations described in the present chapter also comprise sediments of Late Jurassic age. Thicknesses of the Lower Cretaceous sediments are given in fig. 15.

Late Palaeozoic to Early Cenozoic geological evolution of the northwestern German North Sea (Entenschnabel): New results and insights

2014 ◽  
Vol 93 (4) ◽  
pp. 147-174 ◽  
Author(s):  
Jashar Arfai ◽  
Fabian Jähne ◽  
Rüdiger Lutz ◽  
Dieter Franke ◽  
Christoph Gaedicke ◽  
...  
Keyword(s):  
North Sea ◽  
Lower Cretaceous ◽  
Late Jurassic ◽  
Structural Element ◽  
The North ◽  
Sedimentary Evolution ◽  
Basin Subsidence ◽  
The North Sea ◽  
Thickness Variations ◽  
Zechstein Salt

AbstractThe results of a detailed seismic mapping campaign of 13 horizons in the northwestern German North Sea, covering Late Permian to Palaeogene sedimentary successions, are presented. Based on the interpretation of four 3D and two 2D seismic surveys, thickness and depth maps of prominent stratigraphic units were constructed. These maps provide an overview of key structural elements, the sedimentation and erosion, and give insights into the evolution of the German Central Graben. The base of the Zechstein Group reaches a maximum depth of 7800 m within the German Central Graben. Lateral thickness variations in the Zechstein reflect the extensive mobilisation of Zechstein salt. Complex rift-related structures, with the Central Graben as the main structural element, were found not later than the Early Triassic. Up to 3000-m thick Triassic sediments are preserved in the eastern German Central Graben of which 1800 m consist of Keuper sediments. The Lower Buntsandstein unit shows increasing thicknesses towards the southeastern study area, likely related to distinct lateral subsidence. As a consequence of uplift of the North Sea Dome, Middle Jurassic sediments were eroded in large parts of the northwestern German North Sea and are only preserved in the German Central Graben. The NNW–SSE oriented John Basin is another important structural element, which shows maximum subsidence during the Late Jurassic. In most parts of the study area Lower Cretaceous sediments are absent due to either erosion or non-deposition. Lower Cretaceous deposits are preserved in the Outer Rough Basin in the northwest and within the German Central Graben. Upper Cretaceous sediments are found at depths between 1500 and 3600 m, reaching a maximum thickness of approximately 1600 m on the Schillgrund High. Contraction and inversion of pre-existing Mesozoic faults during the Late Cretaceous is distinct at the Schillgrund Fault, i.e. the eastern border fault of the Central Graben. The Palaeogene is predominantly a period of strong basin subsidence. Within 37 Myrs, up to 1400 m of Palaeogene sediments were deposited in the northwesternmost part of the study area. Detailed mapping of salt structures enables a reconstruction of halokinetic movements over time and a deciphering of the influence of the Zechstein salt on the sedimentary evolution during the Mesozoic and Cenozoic. Increasing sediment thicknesses in rim-synclines indicate that most of the salt structures in the German Central Graben had their main growth phase during the Late Jurassic.

Lithology and subsidence in the North Sea

1982 ◽  
Vol 305 (1489) ◽  
pp. 85-99 ◽  
Keyword(s):  
North Sea ◽  
Late Jurassic ◽  
Late Carboniferous ◽  
Delta Front ◽  
Submarine Fans ◽  
The North ◽  
Late Tertiary ◽  
Moray Firth ◽  
Deltaic Sedimentation ◽  
The North Sea

The North Sea sedimentary basin has developed on the northwestern margin of the European tectonic plate and contains an almost continuous record of epeirogenic marine and deltaic sedimentation from Carboniferous to Recent times. The subsidence required to accommodate the pile of sediment deposited, which in places exceeds 12 km, has been brought about at various times and in various places by differing geodynamical processes. As a result the types of sedimentary rocks deposited vary widely both in time and space, but the nature of the mechanism is reflected in the sedimentary type deposited. The following broad generalizations can be made. The late Carboniferous was a period of deltaic sedimentation during which eustatic changes in sea level or local variations in subsidence rates are reflected in the typical Coal Measures swamp deposits. Late Carboniferous - early Permian times saw the silting up of this basin, and in an arid climate aeolian sands were deposited grading laterally to sabkha shales and evaporites. The Permian culminated in a series of widespread marine incursions during which repetitive evaporites were deposited. Triassic times were marked by a period of major rifting and the deposition of thick sequences of continental elastics in the north, while widespread marine sedimentation persisted in southern areas. Jurassic times saw the re-establishment of marine to deltaic deposition in a series of basins possibly controlled in their distribution by the Triassic fault systems. Late Jurassic deposits were laid down in a sea whose bathymetry reflected the structure of the underlying horsts and grabens inherited from Triassic times, and towards the close of the Jurassic the bottom waters at least of this sea become increasingly stagnant. Sands deposited during the late Jurassic were deposited as near-shore marine bars, beach sands, and proximal and distal submarine fans. Triassic to early Cretaceous deposition was concentrated in the areas now occupied by the main grabens of the North Sea, i.e. the Viking, Central and Moray - Witch Ground grabens. Subsequent deposition in late Cretaceous to Tertiary times took place in a more widely subsiding area, resulting in progressive onlap onto the surrounding basin margins. Deposition within this broadly subsiding and relatively unfaulted basin is characterized by chalky limestones in southern areas, giving way laterally to shales and minor sands to the north. During early Tertiary times a large delta was formed in the area beneath the present Moray Firth, and from this delta a supply of sand was fed into submarine fans to the northeast and southeast of the delta front. Late Tertiary deposition is largely represented by a monotonous sequence of marine shales.

scholarly journals Structural outline and development

1982 ◽  
Vol 8 ◽  
pp. 9-26
Author(s):  
Claus Andersen ◽  
Jens Christian Olsen ◽  
Olaf Michelsen ◽  
Erik Nygaard
Keyword(s):  
North Sea ◽  
Early Cretaceous ◽  
Southern North Sea ◽  
The North ◽  
Moray Firth ◽  
History Of ◽  
The North Sea ◽  
Broad Complex ◽  
East West ◽  
German Basin

The Central Graben is a broad, complex trough with a long history of differential subsidence. It was probably initiated in the Permian and was controlled by major rifting during the Mesozoic. To the south in the Dutch sector the trough is divided into two parts. From here it passes northwards and divides the southern North Sea Basin into the Anglo-Dutch Basin and the Northwest German Basin. It also separates the Mid North Sea High from the Ringkøbing-Fyn High. These highs form broad, east-west trending, relative stable ridges. The further continuation of the Central Graben is to the northwest, towards the centre of the North Sea, where it passes into the Viking Graben and the Moray Firth Basin at about 58° N. Where the Central Graben divides the two major highs, there is an elongate central narrow horst, the Dogger High, which is the southernmost of a row of mid-Graben highs. Both sides of the Graben are clearly defined by normal rotational faults that were intermittently active from Triassic to Early Cretaceous times.

AN EARLY CRETACEOUS SOURCE ROCK IN THE KENDREW TERRACE, DAMPIER SUB-BASIN?

1996 ◽  
Vol 36 (1) ◽  
pp. 477 ◽  
Author(s):  
S. Ryan-Grigor ◽  
C. M. Griffiths
Keyword(s):  
Source Rock ◽  
North Sea ◽  
Early Cretaceous ◽  
Late Jurassic ◽  
Large Scale ◽  
Free Water ◽  
Organic Content ◽  
Source Rocks ◽  
The North ◽  
Northern North Sea

The Early to Middle Cretaceous is characterised worldwide by widespread distribution of dark shales with high gamma ray readings and high organic contents defined as dark coloured mudrocks having the sedimentary, palaeoecological and geochemical characteristics associated with deposition under oxygen-deficient or oxygen-free bottom waters. Factors that contributed to the formation of the Early to Middle Cretaceous 'hot shales' are: rising sea-level, a warm equable climate which promoted water stratification, and large scale palaeogeographic features that restrict free water mixing. In the northern North Sea, the main source rock is the Late Jurassic to Early Cretaceous Kimmeridge Clay/Draupne Formation 'hot shale' which occurs within the Viking Graben, a large fault-bounded graben, in a marine environment with restricted bottom circulation and often anaerobic conditions. Opening of the basin during a major trans-gressive event resulted in flushing, and deposition of normal open marine shales above the 'hot shales'. The Late Callovian to Berriasian sediments in the Dampier Sub-basin are considered to have been deposited in restricted marine conditions below a stratified water column, in a deep narrow bay. Late Jurassic to Early Cretaceous marine sequences that have been cored on the North West Shelf are generally of moderate quality, compared to the high quality source rocks of the northern North Sea, but it should be noted that the cores are from wells on structural highs. The 'hot shales' are not very organic-rich in the northern Dampier Sub-basin and are not yet within the oil window, however seismic data show a possible reduction in velocity to the southwest in the Kendrew Terrace, suggesting that further south in the basin the shales may be within the oil window and may also be richer in organic content. In this case, they may be productive source rocks, analogous to the main source rock of the North Sea.

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