The Jabel Sayid Complex, Arabian Shield; geochemical constraints on the origin of peralkaline and related granites

• Published in: Journal of the Geological Society Vol. 143; no. 2; pp. 287 - 295
• Main Authors: Harris, N. B. W, Marzouki, F. M. H, Ali, S
• Format: Journal Article
• Language: English
• Published: London Geological Society of London 01-03-1986; The Geological Society of London; Geological Society
• Subjects: actinides; alkaline earth metals; amphibole group; Arabian Peninsula; Arabian Shield; Asia; barium; biotite; calc-alkalic composition; chain silicates; clinoamphibole; composition; Earth sciences; Earth, ocean, space; europium; Exact sciences and technology; Geochemistry; granites; hornblende; igneous and metamorphic rocks; igneous rocks; isotopes; Jabel Sayid Complex; lithophile elements; magmas; metals; mica group; monzogranite; peralkalic composition; petrology; plutonic rocks; rare earths; Saudi Arabia; sheet silicates; silicates; Soil and rock geochemistry; Sr-87/Sr-86; stable isotopes; strontium; uranium; Paleozoic; Cambrian; Alkalic composition; Sr/Rb; Major elements; Igneous rocks; Trace elements; Absolute age; Arabian Shield; Granites
• ISSN: 0016-7649; 2041-479X
• DOI: 10.1144/gsjgs.143.2.0287

The two main rocks in the area require separate sources. The approx 572 m.y.-old biotite-hornblende monzogranite shows both LIL-enrichment and HREE-depletion, characteristic of a calc- alkaline magma derived from within a hydrated mantle wedge. The approx 534 m.y.-old aegirine-arfvedsonite peralkaline granite is enriched in high-field-strength (HFS) elements and depleted in Sr, Ba and Eu, and a F-bearing fluid phase is necessary. The resulting metasomatic rock types include an aplitic rim with a high content of HFS elements which is a potential economic source of U, and a red granite with varying abundances of trace elements and strong Eu depletion. The peralkaline granite is typical of an intra-plate tectonic environment with trace elements controlled by volatiles, probably mantle-derived.