|Botoman (Lower Cambrian) turbid- and clear-water reefs and associated environments from the High Atlas, Morocco|
Álvaro, J.J.; Clausen, S. (2007). Botoman (Lower Cambrian) turbid- and clear-water reefs and associated environments from the High Atlas, Morocco, in: Álvaro, J.J. et al. (Ed.) Palaeozoic reefs and bioaccumulations: climatic and evolutionary controls. Geological Society Special Publication, 275: pp. 51-70
In: Álvaro, J.J. et al. (Ed.) (2007). Palaeozoic reefs and bioaccumulations: climatic and evolutionary controls. Geological Society Special Publication, 275. Geological Society: London. ISBN 978-1-86239-221-2. viii, 291 pp., more
In: Hartley, A.J. et al. (Ed.) Geological Society Special Publication. Geological Society of London: Oxford; London; Edinburgh; Boston, Mass.; Carlton, Vic.. ISSN 0305-8719, more
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Exposures of the Botoman (Lower Cambrian), Lemdad and Issafen formations on the Lemdad syncline, southern High Atlas, provide an excellent example of the interactions between tectonic events, magmatic activity and carbonate productivity. The major factors that controlled the nucleation of carbonate factories on the Botoman High Atlas platform were: (i) synsedimentary tectonism, as normal faulting resulted in tilting of fault blocks causing irregular topographies and subsequent sharp erosion; (ii) volcanism, because pyroclastic influx smothered carbonate factories except in distal areas of the platform or during quiescent episodes of volcanic activity; and (iii) the influence of successive shoaling parasequences. The Botoman reefs exhibit a wide range of external morphologies, including tabular (biostromes) and domal (bioherms and patches) boundstones, which do not exceed 3.5 m of thickness. Although archaeocyathan-microbial reefs only developed under clearwater conditions, microbial reefs grew also under turbid-water conditions. Domal and digitate stromatoids, Girvanella crusts, Epiphyton bushes and thromboid-stromatoid intergrowths document the ability of some microbial communities to develop heterotrophic strategies when submitted to a moderate terrigenous input. Turbidity was a major ecological factor that constrained development of filter/suspension-feeder and phototrophic organisms, but not necessarily of benthic non-phototrophic microbial communities.