Discussion of the paper by Yahya et al. 2018 entitled 'Paleoenvironmental and paleoclimatic conditions during the deposition of the bauxite layer (Upper Cretaceous) using multi-proxy geochemical and palynological analyses, in the Zabirah Area, Northern Saudi Arabia' (Arabian Journal of Geosciences v.11, Article No.15)

摘要

Yahya et al. (2018) interpreted the palaeoenvironmental and palaeoclimatic conditions prevalent during the formation of the Late Cretaceous Az Zabirah Bauxite in Northern Saudi Arabia. They suggest that claystones associated with the bauxite profile are of Maastrichtian age based on palynology. This age interpretation is counter to the evidence of decades of detailed mapping and biostratigraphic analyses conducted by specialists from the Bureau de Recherches Geologiques et Minieres (BRGM) that demonstrate an Albian to Cenomanian age for the Az Zabirah Bauxite. This older age is even reported in Yahya et al.'s text quoting BRGM and Arabian American Oil Company palynology reports yet, for reasons that remain obscure, was rejected in favour of an unsubstantiated Maastrichtian age. More recent publications on the Cretaceous stratigraphy of Saudi Arabia were not cited. Furthermore, the palynology presented in the paper does not confirm their age interpretation. A second bauxite horizon, the "Pre-Aruma Bauxite" is present nearby but all descriptions and illustrations in the paper suggest that this is not the studied horizon. Moreover, recent Sr isotope dating suggests that the "Pre-Aruma Bauxite" is older than Middle Campanian. The value of sedimentological, palaeoclimatic and palaeoenvironmental interpretations requires them to be placed in their correct stratigraphic context. The authors have singularly failed to achieve this in their publication.