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Megaspore assemblages from the Are Formation (Rhaetian-Pliensbachian) offshore mid-Norway, and their value as field and regional stratigraphical markers

Peter H. Morris, Alex Cullum, Martin A. Pearce and David J. Batten
Megaspore assemblages from the Are Formation (Rhaetian-Pliensbachian) offshore mid-Norway, and their value as field and regional stratigraphical markers
Journal of Micropalaeontology (November 2009) 28, Part 2: 161-181

Abstract

A megaspore biozonation of the non-marine Are Formation is proposed, based on a micropalaeontological analysis of key Haltenbanken area wells (Block 6608/11). The lower part of the Are Formation is divisible into Banksisporites pinguis, Nathorstisporites hopliticus and Horstisporites areolatus zones, and subzones, occupying the Rhaetian-Hettangian interval. In the upper Are Formation a marked turnover of megaspore assemblages is evident, with the appearance of several species of Trileites and the mesofossil Kuqaia quadrata. On this basis, the biozonation is extended into the Sinemurian-Pliensbachian, with the recognition of the Kuqaia quadrata Zone and subzones. Reference to selected wells in the Urd Field (Block 6608/10) and further south demonstrates that these biozones correlate across the northern Haltenbanken region. Biozonal boundaries are calibrated with miospore/microplankton markers where possible, to provide a robust bio-chronostratigraphical framework with which to evaluate the stratigraphy of the Are Formation and its reservoir units. Comparison with published European biostratigraphical data shows that a similar megaspore succession exists through the Rhaeto-Liassic interval, with shifts in megaspore composition occurring within the same time intervals. On this evidence it is suggested that the megaspore biozones identified are regionally extensive and may reflect palaeoclimatic controls on the distribution of the megaspore-producing plants. It is concluded that megaspores are a stratigraphically important microfossil group, which should be utilized routinely in Upper Triassic-Jurassic oil field and regional biostratigraphical studies. J. Micropalaeontol. 28(2): 161-181, November 2009.


ISSN: 0262-821X
EISSN: 2041-4978
Serial Title: Journal of Micropalaeontology
Serial Volume: 28, Part 2
Title: Megaspore assemblages from the Are Formation (Rhaetian-Pliensbachian) offshore mid-Norway, and their value as field and regional stratigraphical markers
Affiliation: Microstrat Services Southcott, Devon, United Kingdom
Pages: 161-181
Published: 200911
Text Language: English
Publisher: British Micropalaeontological Society, London, United Kingdom
References: 43
Accession Number: 2011-042500
Categories: Stratigraphy
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. strat. col., 3 plates, 1 table, geol. sketch map
N65°00'00" - N66°00'00", E07°00'00" - E08°00'00"
Secondary Affiliation: StatoilHydro, NOR, NorwayUniversity of Manchester, GBR, United Kingdom
Country of Publication: United Kingdom
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute.
Update Code: 201124
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