| Abstract: | 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{single bond}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. ?? 1986. |
| Genre: | Article |
| ProdID: | 70030615 |
| Citation Author: | Liddicoat, W. K.; Ramsay, C. R.; Hedge, C. E. |
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| Citation End Page: | 150 |
| Citation Issue: | C |
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| Citation Language: | English |
| Citation Larger Work Title: | Journal of African Earth Sciences |
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| Citation Number Of Pages: | 12 |
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| Citation Search Results Text: | Cambrian nepheline syenite complex at Jabal Sawda, Midyan region, Kingdom of Saudi Arabia; 1986; Article; Journal; Journal of African Earth Sciences; Liddicoat, W. K.; Ramsay, C. R.; Hedge, C. E. |
| Citation Start Page: | 139 |
| Citation Volume: | 4 |
| Citation Year: | 1986 |
| Type: | citation/reference |
| Text: | Cambrian nepheline syenite complex at Jabal Sawda, Midyan region, Kingdom of Saudi Arabia; 1986; Article; Journal; Journal of African Earth Sciences; Liddicoat, W. K.; Ramsay, C. R.; Hedge, C. E. |
| URL (THUMBNAIL): | http://pubs.er.usgs.gov/thumbnails/outside_thumb.jpg |
| Date Other: | Wed, 1 Jan 1986 00:00 -0600 |
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