Palygorskite in the Eocene Rocks of the Dammam Dome, Saudi Arabia

Abstract

Abstract--Clay mineralogy and petrography of the Early to Middle Eocene succession of the Dammam dome, Saudi Arabia, comprising the Rus and Dammam Formations, were studied using X-ray powder diffraction, light microscopy, and scanning electron microscopy. These formations consist of alternations of dolomite, dolomitic marl, claystone, and shale. The rocks were deposited and subjected to early diagenetic dolomitization in a shallow, coastal marginal basin characterized by rapid changes in salinity. Palygorskite occurs as interwoven fibrous mats forming fine laminae in shales and as coatings and porefilling and pore-bridging cements in dolomitic marls. This textural evidence suggests a direct chemical precipitation, mostly post-dating dolomitization. Magnesium concentrations in presence of dolomite was sufficient for palygorsldte precipitation; the necessary Si and AI were derived by dissolution of silicates under alkaline conditions. The maximum development of palygorskite was near the top of the Dammam Formation, which was deposited during a marine transgression in the Lutetian. The formation of palygorskite in marginal restricted basins in eastern Saudi Arabia took place during Paleocene-Middle Eocene time and was contemporaneous with similar occurrences in the Tertiary basins of West Africa.

Dolomite dissolution: An alternative diagenetic pathway for the formation of palygorskite clay

“…Based on the observation that palygorskite formed cements around dolomite crystals, Çağatay () concluded that palygorskite must have precipitated after dolomitization. Çağatay () further contended that the presence of dolomite is evidence that Mg concentrations in the pore fluids were high enough to support subsequent palygorskite precipitation, with Si and Al supplies coming from the dissolution of detrital silicate minerals under alkaline conditions. The Çağatay () model postulated that marine‐derived pore fluids could provide the necessary Mg to form dolomite and palygorskite in sequence.…”

Engineering geological characterisation of the Barzaman Formation, with reference to coastal Dubai, UAE

“…Aiban (2006Aiban ( , 2007 observed palygorskite coated gypsum in eastern Saudi Arabia that suggested precipitation from hypersaline solutions during dry intervals. Cagatay (1990) investigated the occurrence of palygorskite in the Dammam Dome, eastern Saudi Arabia and suggested that the palygorskite was authigenic forming in a marginal restricted basin during Palaeocene-Middle Eocene time. Aqrawi (1993) O -Ciullo, 1996) is a member of the palygorskite and sepiolite (formerly hormite) clay mineral group of phyllosilicates which include attapulgite (Anthony et al, 2001).…”

Synthesis, characterization of palygorskite supported zero-valent iron and its application for methylene blue adsorption

“…The unmodified palygorskite (Fig. 5a) shows bundles of close packed fibres [33] or mat of tightly interwoven fibres [34], with variable thickness and length. These fibres have flat or straight shapes and are oriented randomly in aggregates similar to that observed in some other studies [11,35].…”