Orthocone nautiloid orientations in Arenig and Llanvirn limestones of Öland, Sweden
作者:
Yngve Grahn,
期刊:
Geologiska Föreningen i Stockholm Förhandlingar
(Taylor Available online 1986)
卷期:
Volume 108,
issue 4
页码: 321-330
ISSN:0016-786X
年代: 1986
DOI:10.1080/11035898609454723
出版商: Taylor & Francis Group
关键词: Orthocone nautiloids;preferred orientation;Ordovician;Öland;neighbour effect
数据来源: Taylor
摘要:
Orientations of the orthocone nautiloids on twenty-three bedding planes in Arenig and Llanvirn (Ordovician) limestones on Öland are analyzed. Nine bedding planes display a bipolar orientation indicating very shallow water. The other fourteen have polymodal orientations, although uniform distributions are rejected statistically. Clusters of orthocones with abnormal distributions are very common on Oland. Experimental data suggest that the clusters are reflecting irregularities on the sea bottom, the so calledneighbour effect.The distribution on either side of the flow direction is probably a combination of the neighbour effect and the particle rotation between conch and sediment. The currents in the Ordovician sea around Öland flowed south and may have paralleled the depth contours. The closest land at that time was probably to the west.
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