کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
4747219 1642083 2013 21 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
Stratigraphic framework and calcareous nannofossil productivity of the Essaouira-Agadir Basin (Morocco) during the Aptian–Early Albian: Comparison with the north-Tethyan margin
ترجمه فارسی عنوان
چارچوب چینه شناسی و عملکرد نانوفسیل آهکی موجود در حوضه اسوانیرا-آگادیر (مراکش) در دوران آلبین زودرس آپتایان: در مقایسه با حاشیه شمال تتییف
موضوعات مرتبط
مهندسی و علوم پایه علوم زمین و سیارات فسیل شناسی
چکیده انگلیسی

In the southern Tethyan margin, the Essaouira-Agadir Basin (EAB), south of Morocco, exhibits well-exposed and fossiliferous sections of Aptian–Albian age. Biostratigraphy by ammonoids and sedimentological analysis have been realized for five sections located along an E-W transect in the EAB. The studied successions were dated from the latest Early Aptian to the Early Albian and are characterized by five major sedimentary discontinuities defining at least four main sedimentary sequences. The Late Aptian–Early Albian succession can be considered a gently westward-dipping ramp, marked by a deepening upward evolution. A quantitative study of calcareous nannofossils and calcium carbonate content has been performed on three of these sections. At this time, the EAB was located in the tropical-equatorial hot arid belt. The decrease in both calcium carbonate content and Nannoconus abundances at the Aptian–Albian transition could be the result of cooler climatic conditions recognized in the EAB, and/or of the associated increasing terrigenous input and nutrients, which hindered carbonate production. In the EAB, the nannofossil productivity is higher below the deposition of dark levels, which are coeval with the Niveau Paquier, recognized as the expression in southern France of the OAE 1b (Early Albian). During the Early Albian, the EAB was characterized by nannofossil fluxes two times lower than the upwelling-influenced Mazagan Plateau (southern Tethyan margin) and eight times lower than the Vocontian Basin (northern Tethyan margin). These results show that, with respect to the northern Tethyan margin, trophic conditions in sea surface waters of the pelagic realm of the southern Tethyan margin were lower. Comparable results obtained by Heldt et al. in the neritic realm of the southern Tethyan margin have been ascribed to more arid climatic conditions.


► Sections of the Essaouira-Agadir Basin (Morocco) are studied for the Aptian–Albian.
► Biostratigraphy by ammonoids and sedimentological analyses are realized.
► Quantitative study of calcareous nannofossils is performed.
► Decrease in carbonate production is observed, linked to cooler climatic conditions.
► Nannofossil fluxes are lower in the southern tethyan margin compared to the north.

ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Cretaceous Research - Volume 39, February 2013, Pages 149–169
نویسندگان
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