The closed basin of the Qa’ Al-Azraq, Jordan records gypsum and sulfur depositions. Analysis of the cored sediments used smear slides, isotope geochemistry of gypsum and sulfur, XRD, and SEM. This study distinguishes the sources of gypsum and sulfur in the basin from four different processes. Algae production was responsible for the presence of laminated sulfur at a depth of 48 m where paleolake levels were at a high stand. Primary gypsum, represented by laminated, thick massive beds, records sulfur isotope values of +15.7‰. This period of the paleolake indicates evaporation processes exceeded precipitation, leading to the deposition of thick, massive bed of gypsum. Other sources of gypsum originate from pyrite oxidation, indicated by the overlapping of sulfur isotope values of gypsum and pyrite at −0.7‰. Bassanite and anhydrite identified in this section resulted from dissolution and recrystallization processes. The application of sulfur isotopic analyses identifies environmental distinct formation processes of sulfate minerals in the Al-Azraq basin. This provides the basis for a model of basin evolution and associated changing climates. Finally, this research considers the effect of sulfate minerals on Al-Azraq basin groundwater.
Bibliographical noteFunding Information:
Our sincere gratitude to the National Resources Authority of Jordan for providing drilling equipment and crews. Their continued support and cooperation is deeply appreciated. We thank the staff of the American Center of Oriental Research ACOR, Amman, Jordan who provided assistance while working in the Al-Azraq Basin. The authors thank Dr. Adina Paytan, University of California Santa Cruz and Dr. Louis Gonzales, University of Kansas for all their support and assistance in offering laboratory access for the geochemistry analyses. The authors also thank reviewers for their valuable contributions. This work was supported by a research fellowship from the American Center of Oriental Research, Amman, Jordan, a grant from the University of Missouri Research Board, and material support from the Natural Resources Authority, Amman, Jordan.
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- Arid lake
- Stable isotope
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