scholarly journals Upper Jurassic – Lower Cretaceous of the Danish Central Graben: structural framework and nomenclature

2003 ◽  
Vol 1 ◽  
pp. 231-246 ◽  
Author(s):  
Peter Japsen ◽  
Peter Britze ◽  
Claus Andersen
Keyword(s):  
North Sea ◽  
Early Cretaceous ◽  
Lower Cretaceous ◽  
Late Jurassic ◽  
Upper Jurassic ◽  
The South ◽  
Structural Element ◽  
Maximum Thickness ◽  
The North ◽  
Half Graben

The Danish Central Graben is part of the mainly Late Jurassic complex of grabens in the central and southern North Sea which form the Central Graben. The tectonic elements of the Danish Central Graben in the Late Jurassic are outlined and compared to those in the Early Cretaceous based on reduced versions of published maps (1:200 000), compiled on the basis of all 1994 public domain seismic and well data. The Tail End Graben, a half-graben which stretches for about 90 km along the East North Sea High, is the dominant Late Jurassic structural feature. The Rosa Basin (new name) is a narrow, north–south-trending basin extending from the south-western part of the Tail End Graben. The Tail End Graben ceased to exist as a coherent structural element during the Early Cretaceous and developed into three separate depocentres: the Iris and Gulnare Basins to the north and the Roar Basin to the south (new names). The Early Cretaceous saw a shift from subsidence focused along the East North Sea High during the Late Jurassic to a more even distribution of minor basins within the Danish Central Graben. The depth to the top of the Upper Jurassic – lowermost Cretaceous Farsund Formation reaches a maximum of 4800 m in the northern part of the study area, while the depth to the base of the Upper Jurassic reaches 7500 m in the Tail End Graben, where the Upper Jurassic attains a maximum thickness of 3600 m. The Lower Cretaceous Cromer Knoll Group attains a maximum thickness of 1100 m in the Outer Rough Basin.

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.

New multituberculate mammal from the Early Cretaceous of eastern North America

2013 ◽  
Vol 50 (3) ◽  
pp. 315-323 ◽  
Author(s):  
Richard L. Cifelli ◽  
Cynthia L. Gordon ◽  
Thomas R. Lipka
Keyword(s):  
North America ◽  
Iberian Peninsula ◽  
Early Cretaceous ◽  
North American ◽  
Lower Cretaceous ◽  
Late Jurassic ◽  
Relative Length ◽  
Central Position ◽  
Eastern North America ◽  
The North

Multituberculates, though among the most commonly encountered mammalian fossils of the Mesozoic, are poorly known from the North American Early Cretaceous, with only one taxon named to date. Herein we describe Argillomys marylandensis, gen. et sp. nov., from the Early Cretaceous of Maryland, based on an isolated M2. Argillomys represents the second mammal known from the Arundel Clay facies of the Patuxent Formation (Lower Cretaceous: Aptian). Though distinctive in its combination of characters (e.g., enamel ornamentation consisting of ribs and grooves only, cusp formula 2:4, presence of distinct cusp on anterobuccal ridge, enlargement of second cusp on buccal row, central position of ultimate cusp in lingual row, great relative length), the broader affinities of Argillomys cannot be established because of non-representation of the antemolar dentition. Based on lack of apomorphies commonly seen among Cimolodonta (e.g., three or more cusps present in buccal row, fusion of cusps in lingual row, cusps strongly pyramidal and separated by narrow grooves), we provisionally regard Argillomys as a multituberculate of “plagiaulacidan” grade. Intriguingly, it is comparable in certain respects to some unnamed Paulchoffatiidae, a family otherwise known from the Late Jurassic – Early Cretaceous of the Iberian Peninsula.

scholarly journals A Cretaceous dinoflagellate cyst zonation for NE Greenland

2019 ◽  
Vol 157 (10) ◽  
pp. 1658-1692 ◽  
Author(s):  
H. Nøhr-Hansen ◽  
S. Piasecki ◽  
P. Alsen
Keyword(s):  
North Sea ◽  
Lower Cretaceous ◽  
Upper Cretaceous ◽  
Barents Sea ◽  
The South ◽  
Norwegian Sea ◽  
Dinoflagellate Cyst ◽  
The North ◽  
Northern North Sea ◽  
First Time

AbstractA palynostratigraphic zonation is for the first time established for the entire Cretaceous succession in NE Greenland from Traill Ø in the south to Store Koldewey in the north (72–76.5° N). The zonation is based on samples from three cores and more than 100 outcrop sections. The zonation is calibrated to an updated ammonite zonation from the area and to palynozonations from the northern North Sea, Norwegian Sea and Barents Sea areas. The palynozonation is primarily based on dinoflagellate cyst and accessory pollen. The Cretaceous succession is divided into 15 palynozones: seven Lower Cretaceous zones and eight Upper Cretaceous zones. The two lowermost zones are new. The following five (Lower Cretaceous) zones have already been described. Two of the Upper Cretaceous zones are new. The zones have been subdivided into 20 subzones, 11 of which have been described previously and one of which has been revised/redefined. Nine subzones (Upper Cretaceous) are new. More than 100 stratigraphical events representing more than 70 stratigraphic levels have been recognized and presented in an event-stratigraphic scheme.

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.

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.

The Auk Field, Block 30/16, UK North Sea

1991 ◽  
Vol 14 (1) ◽  
pp. 227-236 ◽  
Author(s):  
Nigel H. Trewin ◽  
Mark G. Bramwell
Keyword(s):  
North Sea ◽  
Lower Cretaceous ◽  
Upper Cretaceous ◽  
The South ◽  
Well Control ◽  
Western Margin ◽  
The North ◽  
Fault Block ◽  
Definition Of ◽  
Central North Sea

AbstractThe Auk field is located in Block 30/16 at the western margin of the Central Graben. Oil is contained in a combination stratigraphic and structural trap which is sealed by Cretaceous chalk and Tertiary claystones. An oil column of up to 400 ft is contained within Rotliegend sandstones, Zechstein dolomites, Lower Cretaceous breccia and Upper Cretaceous chalk. Production has taken place since 1975 with 80% coming from the Zechstein, in which the best reservoir lithology is a vuggy fractured dolomite where porosity is entirely secondary due to the dolomitization process and leaching of evaporites. Both Rotliegend dune slipface sandstones, and the Lower Cretaceous breccia comprising porous Zechstein clasts in a sandy matrix, also contribute to production. Poor seismic definition of the reservoir results in reliance on well control for detailed reservoir definition. The field has an estimated ultimate recovery of 93 MMBBL with 13 MMBBL remaining at the end of 1988.The Auk field is situated in Block 30/16 of the Central North Sea about 270 km ESE from Aberdeen in 240-270 ft of water (Fig. 1). The field covers an area of about 65 km2 and is a combination of tilted horst blocks and stratigraphic traps, located at the western margin of the South West Central Graben. The Auk horst is about 20 km long and 6-8 km wide, with a NNW-SSE trend. It is bounded on the west by a series of faults with throws of up to 1000 ft, and the eastern boundary fault has a throw of 5000 ft in the north reducing to zero in the south (Fig. 2). The horst is a westward tilted fault block in the north which grades into a faulted anticline in the south. The Auk accumulation is largely contained within Zechstein dolomites and is ultimately sealed by Cretaceous chalk which overlies the base Cretaceous erosion surface. An E-W cross-section of the field is illustrated by Fig. 3. Auk was the first of the alphabetical sequence of North Sea sea-bird names used for Shell/ Esso fields.

The Miller Field, Blocks 16/7B, 16/8B, UK North Sea

1991 ◽  
Vol 14 (1) ◽  
pp. 159-164 ◽  
Author(s):  
S. K. Rooksby
Keyword(s):  
North Sea ◽  
Seismic Data ◽  
Lower Cretaceous ◽  
Upper Jurassic ◽  
Oil Field ◽  
The South ◽  
Submarine Fan ◽  
Western Margin ◽  
Average Porosity ◽  
Slow Velocity

AbstractThe Miller Oil Field is located on the western margin of the South Viking Graben in UKCS Blocks 16/7b and 16/8b. The oil is trapped in Upper Jurassic turbidite sands shed from the Fladen Ground Spur via the Brae complex submarine fan systems. The reservoir sands are of good quality with an average porosity of 16% and permeabilities occasionally in excess of 1 Darcy. The trap is formed within a subtle structural-stratigraphic combination. Overlying slow velocity Lower Cretaceous sediments produce a time flat which, after depth conversion, produces a 3-way dip closed feature. The trap is completed by stratigraphic pinchout of the reservoir sands to the northwest. The most recent (1985) seismic data allow the top reservoir reflector to be picked directly, which was not the case during the exploration and appraisal phase, when only the Top Kimmeridge Clay seismic pick could be made. The estimate of recoverable hydrocarbons is currently 300 MMBBL of oil and 570 BCF of gas. Development drilling commenced early in 1989. No results are yet available.

Jura-Cretaceous (Oxfordian to Cenomanian) stratigraphy of the north-central Bowser Basin, northern British Columbia

1989 ◽  
Vol 26 (5) ◽  
pp. 1001-1012 ◽  
Author(s):  
H. O. Cookenboo ◽  
R. M. Bustin
Keyword(s):  
British Columbia ◽  
Lower Cretaceous ◽  
Middle Jurassic ◽  
Late Jurassic ◽  
Upper Jurassic ◽  
Thick Section ◽  
North Central ◽  
The North

Three new formations of Late Jurassic and Early to mid-Cretaceous age are defined for a 2000 m thick section of Jura-Cretaceous rocks exposed in the north-central Bowser Basin. The Currier Formation (Oxfordian to Kimmeridgian or Tithonian) consists of 350–600 m of interbedded shales, siltstones, sandstones, coals, and carbonates. The McEvoy Formation (Barremian to as young as Albian) consists of 400–800 m of siltstones and shales with minor sandstones, thin coals, limestones, and conglomerates. The Devils Claw Formation (in part mid-Albian to Cenomanian) consists of 300–600 m of strata characterized by thick pebble and cobble conglomerates, with associated coarse sandstones and minor siltstones and shales.Two successive coarsening-upward sequences are identified in the study area. The first begins with Middle Jurassic marine shales of the Jackson unit grading upwards to coarser Upper Jurassic facies of the Currier Formation. The Currier Formation is conformably or unconformably overlain by siltstones and shales of the Lower Cretaceous McEvoy Formation, which forms the base of a second coarsening-upward sequence. Conglomerates appear with increasing frequency in the upper McEvoy and are the dominant lithology of the overlying Devils Claw Formation. The contact between the McEvoy and Devils Claw formations is gradational. The Devils Claw Formation forms the top of the second coarsening-upward sequence.The Currier Formation (Late Jurassic) is equivalent to the upper units of the Bowser Lake Group. The McEvoy and the Devils Claw formations (Barremian to Cenomanian) are coeval with the Skeena Group (Hauterivian? to Cenomanian). A probable unconformity separating the Upper Jurassic Currier Formation from the Lower Cretaceous McEvoy Formation correlates with a hiatus in the southern Bowser Basin and probably represents a regional unconformity.

Depositional environments and paleogeography in the Albian Moosebar Formation and adjacent fluvial Gladstone and Beaver Mines formations, Alberta

1984 ◽  
Vol 21 (6) ◽  
pp. 698-714 ◽  
Author(s):  
David R. Taylor ◽  
Roger G. Walker
Keyword(s):  
Brackish Water ◽  
Late Jurassic ◽  
Major Change ◽  
Depositional Environments ◽  
Fluvial Deposits ◽  
Maximum Thickness ◽  
The North ◽  
Major Exception ◽  
Flow Directions ◽  
Sand Bodies

The marine Moosebar Formation (Albian) has a currently accepted southerly limit at Fall Creek (Ram River area). It consists of marine mudstones with some hummocky and swaley cross-stratified sandstones indicating a storm-dominated Moosebar (Clearwater) sea. We have traced a tongue of the Moosebar southward to the Elbow River area (150 km southeast of Fall Creek), where there is a brackish-water ostracod fauna. Paleoflow directions are essentially northwestward (vector mean 318°), roughly agreeing with turbidite sole marks (329°) in the Moosebar of northeastern British Columbia.The Moosebar sea transgressed southward over fluvial deposits of the Gladstone Formation. In the Gladstone, thick channel sands (4–8 m) are commonly multistorey (up to about 15 m), with well developed lateral accretion surfaces. The strike of the lateral accretion surfaces and the orientation of the walls of channels and scours indicate northwestward flow (various vector means in the range 307–339°). The Moosebar transgression was terminated by construction of the Beaver Mines floodplain, with thick, multistorey sand bodies up to about 35 m thick. Flow directions are variable, but various vector means roughly cluster in the north to northeast segment. This indicates a major change in dispersal direction from the Gladstone and Moosebar formations.A review of many Late Jurassic and Cretaceous units shows a dominant dispersal of sand parallel to regional strike. This flow is mostly north-northwestward (Passage beds, Cadomin, Gladstone, Moosebar, Gates, Chungo), with the southeasterly dispersal of the Cardium being the major exception. Only at times of maximum thickness of clastic input (Belly River and higher units, and possibly Kootenay but there are no published paleocurrent data) does the sediment disperse directly eastward or northeastward from the Cordillera toward the Plains.

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