کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
4729534 | 1640245 | 2010 | 9 صفحه PDF | دانلود رایگان |
![عکس صفحه اول مقاله: Foraminiferal biostratigraphy of the Toarcian deposits (Lower Jurassic) from the Middle Atlas (Morocco). Comparison with western Tethyan areas Foraminiferal biostratigraphy of the Toarcian deposits (Lower Jurassic) from the Middle Atlas (Morocco). Comparison with western Tethyan areas](/preview/png/4729534.png)
The Toarcian sediments of the Middle Atlas show hemipelagic facies deposited in platform to basinal environments. They are represented by: (a) marly thick sections that accumulated in troughs under restricted dysoxic conditions, and (b) condensed sections of marly limestones found on fairly high ridges. The micropaleontological study of benthic foraminifera allowed us to establish the biostratigraphic extension of the different registered species. From the stratigraphic distribution of the benthic foraminifera two renewal phases can be characterized: one at the base of the Polymorphum Zone, and the other inside the Bifrons Zone. Five biozones were thus established (Lingulina gr. tenera and Marginulina gr. prima Biozone; Lenticulina obonensis mg Planularia Biozone; Lenticulina pennensis mg Marginulinopsis and Ichtyolaria hauffi Biozone; Nodosariapulchra and Lenticulina ferruginea mg Falsopalmula Biozone; Lenticulinadorbignyi Biozone). These stratigraphic sub-divisions based on the benthic foraminifera are a useful tool when ammonoids are scarce. The Toarcian benthic foraminifera of the Middle Atlas are similar to the foraminiferal associations from neighbouring regions in the Maghreb (Morocco and Algeria) and Southwestern Europe (Spain, France and Portugal).
Journal: Journal of African Earth Sciences - Volume 57, Issues 1–2, April 2010, Pages 154–162