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The AAPG/Datapages Combined Publications Database
AAPG Bulletin
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The Jurassic-lowermost Cretaceous succession of East Greenland was deposited in a seaway formed over a series of old extensional basins between Greenland and Norway. The succession is interpreted within a sequence stratigraphic framework with the main emphasis on the Middle and Upper Jurassic. The vertical and lateral dimensions of the stratigraphic units are measured in kilometers and hundreds of kilometers, respectively. The interpretation is comparable to seismic-scale sequence stratigraphy, and the results can be compared directly to those derived from conventional reflection-seismic studies of subsurface successions. Sequence boundaries, and thus sequences, are defined differently by various research groups. In contrast, systems
tracts
representing linkages of deposi
ional
systems
are considered the basic building blocks in both genetic and sequence stratigraphy. In the present study,
systems
tracts
are recognized as the unit of highest rank within the concept of sequence stratigraphy. Ten major
systems
tracts
are recognized. A Pliensbachian-Toarcian transgressive
systems
tract consisting of a slightly retrogradational parasequence set is overlain by a thin uppermost Toarcian-Aalenian(?) highstand
systems
tract (290-420 m in total thickness). The 140-700 m thick upper Bajocian-middle Callovian interval is represented by a basal aggradational to slightly retrogradational parasequence set interpreted as a shelf margin
systems
tract transitional to a transgressive
systems
tract. This interval is overlain by a strongly onlapping retrogradational set form
d under rapid
sea
level
rise and high sediment input, and interpreted as a transgressive
systems
tract. The upper Callovian-middle Oxfordian forms a composite progradational parasequence set that downlaps onto the top of the transgressive
systems
tract and represents a highstand
systems
tract. The transitional strata between the two
systems
tracts
are highly condensed distally and contain the maximum flooding surface. Major regional deepening began in the late Oxfordian, and a thick succession of shales and turbiditic gully sandstones was deposited across the whole region. This succession represents another transgressive
systems
tract formed during a rapid
sea
level
rise reaching highstand in the early Volgian when a sandy highstand
systems
tract prograded into the basin. The middle Volg
an-Valanginian interval was characterized by rotational block faulting in northern East Greenland, in contrast to southern East Greenland, which continued its regular subsidence. A succession of a lowstand or shelf margin
systems
tract, a transgressive
systems
tract, and a highstand
systems
tract is recognized in both regions. This similarity may allow separation of
sea
level
and tectonic signals in the two contemporaneous successions.
The sequence stratigraphic analysis forms the basis for a coherent genetic model for the Jurassic-lowermost Cretaceous succession. The model may prove to be of value in interpreting deeply buried correlative hydrocarbon reservoirs in the northern North Sea
and the Norwegian shelf.
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