Geochemistry and spatial distribution of Neoproterozoic dike swarms from the northwestern tip of the Arabian-Nubian Shield: Implications for crustal extension

Hind Ghanem; Abeer Salman; Ryan J. McAleer; Cees W. Passchier; Ghaleb H. Jarrar

doi:10.1016/j.jafrearsci.2025.105743

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Geochemistry and spatial distribution of Neoproterozoic dike swarms from the northwestern tip of the Arabian-Nubian Shield: Implications for crustal extension

Hind Ghanem·Abeer Salman·Ryan J. McAleer·Cees W. Passchier·Ghaleb H. Jarrar

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Abstract

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 40 Ar/ 39 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.

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Journal of African Earth Sciences Article

Source-reported bounding extent: 12.65452725801191° to 29.907477528272565° latitude; 31.797747826914417° to 45.178411722882146° longitude. This indicates report coverage, not an exact sampling location. View area on OpenStreetMap.

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Hind Ghanem, Abeer Salman, Ryan J. McAleer, Cees W. Passchier, Ghaleb H. Jarrar. 2025. Geochemistry and spatial distribution of Neoproterozoic dike swarms from the northwestern tip of the Arabian-Nubian Shield: Implications for crustal extension. https://doi.org/10.1016/j.jafrearsci.2025.105743

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