C.R. Ramsay C. E. Hedge W.K. Liddicoat 1986 <div id="preview-section-abstract"><div id="abstracts" class="Abstracts u-font-serif text-s"><div id="ab1" class="abstract author" lang="en"><div id="aep-abstract-sec-id9"><p>The only nepheline syenite complex presently known in the Arabian Shield is at Jabal Sawda, about 30 km S of Haql in the extreme NW of Saudi Arabia. It is a post-tectonic, composite intrusion with a crudely concentric structure. A core of leuco-nepheline syenite, a partial ring of mela-nepheline syenite, and an almost complete outer ring of alkali-feldspar syenite are the main rock units. Several mega-inclusions of porphyritic nepheline syenite, nepheline monzosyenite, malignite and ijolite are present in the leuco-nepheline syenite. The chemical composition is notable for very high values of Al₂O₃, Na₂O, Ba, La, Nb, Sr and Zr. U<img src="https://sdfestaticassets-us-east-1.sciencedirectassets.com/shared-assets/55/entities/sbnd.gif" alt="single bond" data-mce-src="https://sdfestaticassets-us-east-1.sciencedirectassets.com/shared-assets/55/entities/sbnd.gif">Pb isotope dating indicates an emplacement age of 553 ± 4 Ma, one of an increasing number of reliable Cambrian isotope dates in the northern Red Sea region.</p></div></div></div></div> application/pdf 10.1016/S0899-5362(86)80075-6 en Elsevier Cambrian nepheline syenite complex at Jabal Sawda, Midyan region, Kingdom of Saudi Arabia article