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Zircon morphology and U-Pb geochronology of seven metaluminous and peralkaline post-orogenic granite complexes of the Arabian Shield, Kingdom of Saudi Arabia

January 1, 1994

The U-Pb zircon method was used to determine the ages of seven metaluminous-to-peralkaline post-orogenic granites located throughout the Late Proterozoic Arabian Shield of Saudi Arabia. Zircons from the metaluminous rocks are prismatic, with length-to-width ratios of about 2-4:1 and small pyramidal terminations. In contrast, zircons from three of the four peralkaline complexes either lack well developed prismatic faces (are pseudo-octahedral) or are anhedral. Some of the zircons from the peralkaline granites contain inherited radiogenic lead. This complicates interpretation of the isotopic data and. in many cases, may make the U-Pb method unsuitable for determining the age of a peralkaline granite. Zircons in the metaluminous granites do not contain inheritance and thus, best-fit chords calculated through the data have upper concordia intercepts that indicate the age of intrusion, and lower intercepts that indicate simple episodic lead loss. The results show that these granites were emplaced during multiple intrusive episodes from 670 to 510 Ma (Late Proterozoic to Cambrian).

Citation Information

Publication Year 1988
Title Zircon morphology and U-Pb geochronology of seven metaluminous and peralkaline post-orogenic granite complexes of the Arabian Shield, Kingdom of Saudi Arabia
DOI 10.3133/ofr88604
Authors John Nicholas Aleinikoff, D. B. Stoeser
Publication Type Report
Publication Subtype USGS Numbered Series
Series Title Open-File Report
Series Number 88-604
Index ID ofr88604
Record Source USGS Publications Warehouse