Abeer Salman
Ryan J. McAleer
Cees W. Passchier
Ghaleb H. Jarrar
Hind Ghanem
2025
<p><span id="_mce_caret" data-mce-bogus="1" data-mce-type="format-caret"><span>Ediacaran dike swarms in the Arabian-Nubian Shield (ANS) provide key insights into post-collisional tectonics and magmatism. This study presents new chemical data, two </span><sup>40</sup><span>Ar/</span><sup>39</sup><span>Ar ages, and spatial distribution analysis for dike swarms in the northernmost ANS exposures in SW Jordan. Hornblende from a lamprophyre sill intruding the Saramuj Conglomerate yielded a plateau age of ∼592 ± 3 Ma, interpreted as the crystallization age of the sill. Micro-cores of sericite-rich domains in altered plagioclase phenocrysts from a dolerite dike intruding ∼586 Ma alkali granite produced ages of ∼580–570 Ma, interpreted as hydrothermal alteration ages, constraining dike emplacement to 586–580 Ma. The geochemistry of investigated dikes varies from alkaline to subalkaline and crosscuts calc-alkaline magmatic rocks. This transition reflects a shift from compression to extension (∼610-590 Ma), lithospheric thinning, and changes in mantle sources. After 590 Ma, magmatism became exclusively alkaline, forming A-type granitoids and dolerites, marking a shift to extensional magmatism. Dikes predominantly follow NE-SW and E-W orientations, with rare N-S, NW-SE, and WNW-ESE trends, suggesting a major horizontal extension direction from NW-SE to N-S. Dike density ranges from 5 to 13 %, averaging ∼9 %, with crustal extension estimates of 9–23 %, averaging 16 %. No correlation was found between dike composition, orientation, or order of emplacement, indicating consistent stress orientation during the final stage (605-580 Ma) of ANS evolution.</span></span></p>
application/pdf
10.1016/j.jafrearsci.2025.105743
en
Elsevier
Geochemistry and spatial distribution of Neoproterozoic dike swarms from the northwestern tip of the Arabian-Nubian Shield: Implications for crustal extension
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