科研之友
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摘要
The Bravaisberget Formation of southern Spitsbergen (the youngest formation of the Sassendalen Group; Middle Triassic-Carnian) comprises a succession of organic-rich and sandy phosphogenic deposits that developed in a marginal part of the Svalbard basin, in response to a high biological productivity event in the Barents Shelf. The basin margin was bounded on the southwest by the elevated structure of the Sorkapp-Hornsund High. North of the high, the subsiding shelf bot tom stretched from south ern to west ern Spitsbergen. The organic-rich, fine-grained sedimentation that gave rise to the formation of the Passhatten Member extended south ward after the Anisian transgression; it reached the top most part of the Sorkapp-Hornsund High during the maximum flooding of the basin in the early Ladinian. The sudden appearance of deltaic deposits of the Karentoppen Member directly after the maximum flooding was a consequence of short-lived tectonic activity of the Sorkapp-Hornsund High and the adjacent land area. Reworking and redistribution of the deltaic sediments during the Ladinian brought about the formation of shallow-marine clastic facies of the Somovbreen Member. Decreasing depositional rates close to the Middle-Late Triassic boundary led to a regional hiatus and the formation of a condensed phosphorite horizon at the top of the Somovbreen Member. The sedimentation of the Bravaisberget Formation ended in the early Carnian. The youngest siliciclastic and spiculitic sediments of the Van Keulen-fjorden Member were deposited in south ern and west ern Spitsbergen in shallow- to marginal-marine environments.
- 出版日期2015
