A Caltech Library Service

Formation of gold-bearing listvenite in the mantle section of the Neoproterozoic Bir Umq ophiolite, Western Arabian Shield, Saudi Arabia

Gahlan, Hisham A. and Azer, Mokhles K. and Asimow, Paul D. and Al-Kahtany, Khaled M. (2022) Formation of gold-bearing listvenite in the mantle section of the Neoproterozoic Bir Umq ophiolite, Western Arabian Shield, Saudi Arabia. Journal of African Earth Sciences, 190 . Art. No. 104517. ISSN 1464-343X. doi:10.1016/j.jafrearsci.2022.104517.

[img] PDF - Accepted Version
See Usage Policy.

[img] MS Word (Supplementary data) - Supplemental Material
See Usage Policy.

[img] MS Excel (Supplementary data) - Supplemental Material
See Usage Policy.


Use this Persistent URL to link to this item:


Serpentinized peridotite and associated listvenites of Neoproterozoic age outcrop in the Bir Umq area of western Saudi Arabia. The mantle section of the Bir Umq ophiolite is extensively serpentinized. Serpentinite host samples are low in Al₂O₃ (0.48–0.75 wt%) and CaO (0.28–1.24 wt%) and have high Mg# (0.90–0.92), indicating a strongly depleted mantle protolith, typically associated with supra-subduction zone environments and more specifically with fore-arc settings. Listvenite bodies of various shapes and sizes developed by alteration of serpentinite. Listvenites occupy the hanging walls of a stack of thrust faults, while serpentinite dominates the footwalls. Based on mineralogical composition and whole-rock geochemistry, the listvenites of Bir Umq are distinguished into carbonate listvenite and silica-carbonate listvenite; the latter is further divided into mineralized and non-mineralized samples. Carbonate listvenite is high in MgO, Fe₂O₃, and CaO, but depleted in SiO₂. Silica-carbonate listvenite is characterized by the presence of rhythmic banding of quartz and carbonate minerals and by the presence of fuchsite. The Bir Umq listvenites preserve various stages of the progressive alteration and metasomatic transformation of their ultramafic protoliths due to interaction with hydrothermal fluids enriched in CO₂, SiO₂, Au, K, and other fluid-mobile elements. The association with thrusting suggests that faults acted as conduits for fluids derived from metamorphism of the underlying units during subduction and obduction. Schistosity and deformation fabrics in carbonate listvenite imply that initial listvenitization took place at conditions similar to the conditions of serpentinization. On the other hand, the absence of deformation fabrics in silica-carbonate listvenite suggests that it postdates serpentinization and therefore represents a separate and later fluid infiltration event. Finally, the mineralized silica-carbonate listvenite is highly enriched in fluid-mobile elements Zn, Pb, Cu, Ag, and most notably Au; this enrichment is not correlated with silica content. This suggests that yet a third fluid infiltration event is responsible for the mineralization and Au enrichment. Au concentrations are 0.84–2.31 ng g⁻¹ in host serpentinite, 26–403 ng g⁻¹ in carbonate listvenite, 152–545 ng g⁻¹ in non-mineralized silica-carbonate listvenite, and 2286–3712 ng g⁻¹ in mineralized silica-carbonate listvenite.

Item Type:Article
Related URLs:
URLURL TypeDescription
Gahlan, Hisham A.0000-0002-4606-5657
Azer, Mokhles K.0000-0002-3711-8630
Asimow, Paul D.0000-0001-6025-8925
Additional Information:© 2022 Elsevier. Received 24 September 2021, Revised 7 March 2022, Accepted 8 March 2022, Available online 17 March 2022. The authors would like to extend their appreciation and gratitude to the Deanship of Scientific Research, King Saud University for funding and supporting this work through Research Group No. RG-1436-036. Analytical work at the Caltech GPS Division Analytical Facilities is partially supported by NSF Grants EAR-0318518 and DMR-0080065. PDA acknowledges NSF award 1911902. The authors are indebted to the editor (Prof. Mohamed G. Abdelsalam) and highly appreciate thoughtful reviews by Prof. Ghaleb Jarrar and an anonymous reviewer. The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
Funding AgencyGrant Number
King Saud UniversityRG-1436-036
Subject Keywords:Arabian shield; Ophiolite; Listvenite; Fuchsite; Sulphides; Gold
Record Number:CaltechAUTHORS:20220318-999082000
Persistent URL:
Official Citation:Hisham A. Gahlan, Mokhles K. Azer, Paul D. Asimow, Khaled M. Al-Kahtany, Formation of gold-bearing listvenite in the mantle section of the Neoproterozoic Bir Umq ophiolite, Western Arabian Shield, Saudi Arabia, Journal of African Earth Sciences, Volume 190, 2022, 104517, ISSN 1464-343X,
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:113972
Deposited By: George Porter
Deposited On:21 Mar 2022 15:29
Last Modified:18 Apr 2022 21:10

Repository Staff Only: item control page