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Facies and early diagenesis of rainwater-fed paleospring calcareous tufas in the Kurkur Oasis area (southern Egypt)

Carbonates and Evaporites • 2022
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Publication Information
Authors Sallam E.S.
Keywords Facies analysis · Depositional environments · Early diagenesis · Tufa · Kurkur oasis
Journal Carbonates and Evaporites
Publisher Springer
Volume 37
Issue 46
Pages Not Available
publication.type International
Paper Link Open Link
Supplementary Materials Not Available
Abstract
The Quaternary calcareous tufas precipitated in the Kurkur Oasis area in the southern Western Desert of Egypt were analyzed
to determine their implications for the construction of environmental conditions during their formation. X-ray diffraction
analysis showed that the tufas consist of low-Mg calcite, whereas macroscopic and microscopic analyses showed
the presence of both allochthonous (clastic) and autochthonous components consisting predominantly of pisoliths, oncoids,
intraclasts, lithoclasts, stromatolites and encrusted plant materials. These tufas form four facies associations that represent
pisolitic intraclastic/lithoclastic oncoidal rudstones, phytohermal /bryophyte framestones, stromatolite-algal boundstones,
and speleothem-like flowstones. These tufa associations were formed within a karstified carbonate terrain by a rainwater-fed
paleospring system comprising waterfalls, slopes, dammed areas, lacustrines-paludal, and fluvial channel margin environments.
Early diagenetic features are cementation, neomorphism and subaerial dissolution. Isotope-geochemical analysis
indicated that the negative δ18O values (between – 13.26 and – 8.89‰ V-PDB) and the negative δ13C values (between
– 3.16 and – 1.62‰ V-PDB) of the studied tufas are consistent with carbonates deposited from meteoric water in regions
with much precipitation.