The Central Atlantic Magmatic Province (CAMP) volcanic sequences of Berrechid and Doukkala basins (Western Meseta, Morocco): Volcanology and geochemistry
Abstract
The Late Triassic-Early Jurassic volcanic succession of the Berrechid and Doukkala basins (Western Meseta, Morocco) comprises two lava flow fields. At the base, the Sidi Mohamed Larbi-Sidi Saïd Mâachou Formation is composed of 1 to 5 flows, while the upper Aïn Bouhachad Formation presents 1 or 2 flows. Lavas are mainly compound pahoehoe flows showing evidence of endogenous growth by inflation, suggesting slow emplacement during sustained eruptive episodes. Textures vary vertically in each lobe (fine to medium-grained intergranular, subophitic to ophitic in the lava core, and aphanitic to glomeroporphyritic in the lava crust). The mineralogy is typical of continental tholeiites: plagioclase, clinopyroxene (augite and pigeonite), and minor amounts of olivine and ferro-titanium oxides. The major and trace element concentrations and/or ratios of the two formations match, respectively, the compositions described elsewhere for the Lower and Intermediate formations of the Central Atlantic Magmatic Province (CAMP) from the Central High Atlas and Argana basin. © 2011 LNEG - Laboratório Nacional de Geologia e Energia, IP.