Abstract
In the western part of the Anti Atlas, the Cambrian formations known since long (Nice, 1924; Bourcard, 1927; Bung & Netlner, 1933), have been the subject of a very detailed stratigraphic approach. The sedimentological work affecting the lower Cambrian of the Western Anti Atlas is rare. It concerns mainly: a lithostratigraphic description and a summary interpretation of the environmental sedimentary formations. Indeed, recent sedimentological data allowed a new lithostratigraphic division of the Lower Cambrian succession in three lithostratigraphic series. These, are characterized, each one, by a particular microbialitic builds ups, resulted, probably, from Lower Cambrian marine ecosystem variations. The first step, the stromatolitic series, represents a long period in which a large area of the Anti-Atlasic platform was occupied by peritidal cyanobacterial mats. The second step, represented by the Thrombolites series, marks a global sea level rise (Thrombolites proliferation) relayed by a massive silico-clastic supply inputs. And the third stage of evolution during which the medium sufficiently deepened to allow the installation of the distal facies platform. The development of the Archaeocyaths seems to be one of the precursors of dendritic form acquired by certain microbial communities. Dating Neoproterozoic, the Archaeocyaths of Ifrane, whose morphological diversity and the microbial communities associated with them, are a focus for the industry of ornamental rocks in Ifrane in the Moroccan western Anti-Atlas. In this area, the structural diversity of the Archaeocyaths is very pronounced, which facilitates the systematic division and their use in stratigraphy. The perforations or pores vary in number, size and arrangement, those whose walls are stretched in the subdivision pore channels or tubes which may be linear, bent, or inclined in the case of thicker walls. Indeed, the main objective of this work is to highlight the “Archaeocyathans mounds” as a geological heritage through the study of varied silico-clastic and carbonate predominate components facies. Regrettably, the surexploitation of the Archaeocyaths in the ornamental industry and mining activities may lead to their death in the absence of regulatory laws of their exploitation. Clues are offered to make the Archaeocyaths a geological site, a geological destination, thing that necessitate the conduct of a number of approaches, the mobilization of various networks of actors but also the establishment or adaptation of infrastructure, home or mediation.
Highlights
Appearing at the onset of the Cambrian (Tommotian), the Archaeocyatheans mounds were already singular again by the end of the mid-Cambrian
They were most abundant during the Lower Cambrian, when they played an important biostratigraphic role (Enay, 1993). These are metazoans that originate directly, but independently from ancestors protozoa. These bioconstructions, can be described as reef structures (Benssaou, 2003; Hamoumi, 2004), by analogy with those described in the formations of Lower and Middle Cambrian trans-Antarctic mountains (Rees et al, 1989)
They thrive under relatively turbulent hydrodynamic conditions (Wood, 1997) and preferably along the edges of slopes of offshore platforms in a hot climate
Summary
Appearing at the onset of the Cambrian (Tommotian), the Archaeocyatheans mounds were already singular again by the end of the mid-Cambrian They were most abundant during the Lower Cambrian, when they played an important biostratigraphic role (Enay, 1993). These are metazoans that originate directly, but independently from ancestors protozoa. These bioconstructions, can be described as reef structures (Benssaou, 2003; Hamoumi, 2004), by analogy with those described in the formations of Lower and Middle Cambrian trans-Antarctic mountains (Rees et al, 1989).
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