- 1Ludwig-Maximilians-Universität München, Faculty of Geosciences, Department of Earth and Environmental Sciences, Munich, Germany (m.dusingizimana@lmu.de)
- 2Lehrstuhl für Astronomische und Physikalische Geodäsie, Technische Universität München, Munich, Germany
- 3Department of Geological Sciences, University of Cape Town, South Africa
- 4Institute of Geophysics ASCR, the Czech Academy of Sciences (CAS), Prague, Czech Republic
Salt-diapir-caprock systems form both subsurface and surface halokinetic features. The world’s best exposed salt-diapir-caprock systems are hosted in the Zagros Mountains, in the arid and mountainous part of Iran. Due to their economic significance, subsurface salt-diapir-caprock systems in various tectonic settings have long been the focus of geosciences research. Biogeochemical subsurface processes, which are thought to be responsible for caprock formation, are also genetically linked to the formation of Pb-Zn deposits and some of the largest native sulfur deposits. In addition, the subsurface systems form hydrocarbon traps that are important for energy exploration. For this reason, extensive studies have been conducted on subsurface caprocks to establish a conceptual lithological model that describes the formation processes and the spatiotemporal relationships of salt-diapir-caprock facies. On the contrary, studies on fully extruded caprock systems remain limited. This scarcity hampers the comparative assessment of the lithological makeup of both extruded and subsurface salt-diapir caprock systems. It also restricts our understanding of the compositional evolution of salt-diapir and caprock materials as they diapirically extrude and become exposed to further modification by subaerial surface processes.
In this study, we explored the potential of satellite-based multispectral ASTER (Advanced Spaceborne Thermal Emission and Reflection Radiometer) and hyperspectral EnMAP (Environmental Mapping and Analysis Program) remote sensing for producing lithological maps of exposed salt-diapir-caprock features in the Zagros Region. We tested our method on three geomorphologically different salt diapirs ― Karmostaj, Siah Taq, and Champeh. We further examined the similarities and differences between our results and the established lithological model of subsurface salt-diapir-caprock systems.
Our results indicate that satellite-based remote sensing offers an efficient approach to producing lithological maps of exposed salt deposits and related caprocks, hence allowing the identification of caprock lithological facies. However, the accuracy of these maps depends on the spectral and spatial resolutions of satellite data. Furthermore, the results allow us to define the fundamental compositional differences between caprock formed under subsurface biogeochemical environments and caprock formed under the influence of surface processes. Specifically, subsurface salt dissolution results in the accumulation of a substantial anhydrite cap. Microbially-driven subsurface caprock-forming processes alter Ca-sulfates into an extensive calcite cap and simultaneously cause iron sulfide mineralization. As diapiring microbial iron sulfides reach shallow-depths and subaerial conditions, they alter into ferric oxides and ferric oxy-hydroxides. Therefore, together with microbial carbonate, the ferric oxides and oxy-hydroxides serve as diagnostic proxies for subsurface caprocks. In contrast, under surface conditions, microbial processes are likely to be unfavorable, leading to the limited amount or lack of biogenic calcite caprocks and iron sulfide mineralization. Caprocks formed under surface conditions thus predominantly comprise quartz- and clay-rich lithologies, which are the main residuals of the dissolution of salt-rich extruded materials, and a limited amount of the Ca-sulfates as surface processes hamper their accumulation.
How to cite: Dusingizimana, M. W., Friedrich, A., Kahle, B., Rieger, S., Heuss-Aßbichler, S., Závada, P., and Zebari, M.: Lithological Characterization of Extruded Salt-Diapir-Caprock Systems in the Zagros Mountains in Iran Using Satellite-Based Multispectral and Hyperspectral Remote Sensing , EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-17849, https://doi.org/10.5194/egusphere-egu25-17849, 2025.