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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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