The Botneheia Formation (Middle Triassic) in Edgeøya and Barentsøya, Svalbard: lithostratigraphy, facies, phosphogenesis, paleoenvironment

• Main Author: Krzysztof P. Krajewski
• Other Authors: The Pennsylvania State University CiteSeerX Archives
• Format: Text
• Language: English
• Subjects: Key words; Svalbard; Middle Triassic; Botneheia Formation; lithostratigraphy; facies; Barentsøya; Blanknuten; Botneheia; Edgeøya; Muen
• Online Access: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.617.5212; http://www.polar.pan.pl/ppr29/PPR29-319.pdf

Svalbard embraces an organic carbon−rich, fine−grained clastic succession (up to 100 m thick) that makes the best petroleum source unit in the region. This paper presents new lithostratigraphic subdivision and detailed description of the formation, followed by its paleoenvironmental interpretation and reconstruction of the depositional history. The Botneheia Fm is subdivided into two members occurring in stratigraphic order: (1) the lower Muen Mb (new unit), and (2) the upper Blanknuten Mb (extended description). Nine informal lithostratigraphic units are defined as well in the formation, five in the Muen Mb (units 1 to 5), and four in the Blanknuten Mb (units 6 to 9). The Botneheia Fm records a sec− ond−order transgressive−regressive cycle in the Triassic succession of Svalbard that was de− veloped in an open shelf environment. It embraces two superimposed, third−order trans− gressive pulses followed by stepwise regression. The rises of sea level were associated with consequent deterioration of bottom environment, from prevailing oxic bottoms in the Muen Mb, through mostly dysoxic bottoms in the upper part of the Muen Mb and the lower part of the Blanknuten Mb, to euxinic conditions in the middle part of the Blanknuten Mb. The re− gressive trend terminated the Svalbard euxinia, and ended up in regional disconformity at top of the Botneheia Fm. Superimposed on the second transgressive pulse was the develop− ment and maintenance of high biological productivity in surficial waters that led to in− creased contribution of organic carbon in sediment and phosphogenesis.