Micropalaeontological evidence of brackish water conditions during deposition of the Knorringfjellet Formation, Late Triassic–Early Jurassic, Spitsbergen

Polar research

Jenö Nagy¹  Sigrid H. Berge² 

[1] Department of Geosciences, University of Oslo, PO Box 1047 Blindern, NO-0316 Oslo, NorwayCorrespondence;Geoservices, Jakob Askelandsvei 21, P.O. Box 1058 Lura, NO-4391 Sandnes, Norway

关键词: Foraminiferal facies;    hyposaline;    hypoxic tendency;    low diversity;    marine shelf;    stratigraphy.;   

DOI  :  10.1111/j.1751-8369.2007.00038.x

学科分类：自然科学（综合）

来源: Co-Action Publishing

【 摘 要 】

The Knorringfjellet Formation is a succession of mudstones and sandstones, ranging in age from Norian to Toarcian in western and west-central Spitsbergen, and contains several unconformities with associated hiatuses. Its foraminiferal succession consists almost exclusively of agglutinated taxa, shows extremely low assemblage diversities and a dominance of small-sized species. These faunal features signalize restricted environmental conditions (in contrast to those of a normal marine shelf). Comparisons with ancient and modern analogues suggest that the main restricting factor was hyposaline conditions, to a lesser extent augmented by hypoxia in near-bottom waters. These conditions were caused by high fluvial influx creating gravity stratified water masses. The depositional area was part of an extensive but shallow shelf embayment, which had an open connection to the north to the polar ocean basin. Discontinuities recognized in the foraminiferal succession indicate depositional unconformities within the fo...

【 授权许可】

CC BY-NC