Clastic Dikes in the Dead Sea Basin
Partners:
Ram Weinberger, Geological Survey of Israel
Amotz Agnon, Institute of Earth Sciences, The Hebrew University, Jerusalem
Naomi Porat , Geological Survey of Israel
Zafrir Levy (PhD student, co-supervisor Yehuda Eyal), Dep. of Geology, Ben Gurion University
Publications: Terra Nova v14, 2002
Abstract
Fanning structures radiating from a central perturbation are known in various geological environments, where different processes produced similar geometry. We describe and analyze fanning clastic dikes in the Dead Sea rift, a new example of diapir-related deformation. The dikes are opening-mode fractures exposed in lacustrine varved marl of the 70-15 ka Lisan Formation. They are arranged mainly in a radial and tangential geometry. The radial traces converge at the “Black Hill” structural dome. The geometry of the fractures is consistent with stresses exerted by the rise of a salt diapir located underneath the Black Hill. The estimated extension of the radial fractures is in good agreement with the present topographic elevation of the hill. The absence of fractures in the overlying Holocene alluvium probably indicates that either the rise of the Black-Hill salt diapir paused or is associated now with a different style of deformation.
The second stage of the clastic dikes research is the core of Zafrir Levi's PhD project. Zafrir is currently completing the map of the dikes, analyzing the strain, and characterizing the fill materials of the dikes, in particular the composition, sources, and transport directions. Analyses of anisotropy of magnetic susceptibility (AMS) were done in collaboration with Tahar Aifa of Rennes 1 university, France.
Study area (left). White arrows on the air photo show examples of radial clastic dikes, which converge at the Black Hill. The circles (dashed white) are centered at the Black Hill, near the white circle.
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Zafrir Levy studies a clastic dike in the Peratzim Creek.
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Rami and Zafrir examine one of the widest dikes in the Amiaz Plain.
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Two types of fill in a clastic dike. A sample for TL dating was collected from the hole behind the hammer. |
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Clastic dikes overlain by Holocene alluvium.
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The "Flour Cave" formed by erosion along a clastic dike, which is seen in the back.
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A natural bridge formed by erosion of a clastic dike, Amiaz Plain. Mount Sedom is in the horizon. |
Incipient erosion reveals a tangential clastic dike on the Amiaz Plain. Mount Sedom is on the right side. back to top
Incipient erosion reveals a radial raclastic dike on the Amiaz Plain. Mount Sedom is in the horizon.
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Rami measures the orientation of a sample for AMS analysis.
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A clastic dike near Masada. The individual dikes here a similar to the dikes in the Peratzim. The general pattern is currently under investigation.
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 Jean Piere near a vertically-layered dike |
 From left: Tahar, Naomi, Zafrir, Rami, Jean Piere in the Peratzim Creek |
 Rami (left) and Zafrir in the Peratzim Creek. |
 Naomi shows a vertically-layered dike |