Quartz Typology And Heavy Minerals As A Provenance Tools For Some Sedimentary Cover (Lower Cretaceous) At Jibal Ad - Dughm, Biyad Formation, East Riyadh District, Saudi Arabia Kingdom

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Author(s) Antar Abdel-Wahab
Pages 792-807
Volume 6
Issue 5
Date May, 2017
Keywords Provenance,Ad-Dughm Sandstone, ZTR Group, Biyad Formation

The purposes of this study is to shed some light on the nature of the source area of the present sandstones using quartz typology and heavy mineral suites. Feldspar and rock fragments do n't give much contribution to the provenance investigation because only very few of them survived weathering and diagenetic processes. No satisfactory provenance studies have been carried out on the basal Biyad Formation of lower Cretaceous sandstone can be regarded as definitive.The Riyadh-1 sandstone ranges in composition of the three components: framework, cement and porosity, varies from a minimum of F52.4C11.8P35.8 to a maximum of F80..3 C8..3 P11.4 and averages F63.0 C10.9 P26.1. Sandstone of the Riyadh-2 area ranges in composition from a minimum of F52.4C11..9P35.7 to a maximum of F78.3.C10..3. P11..4 and averages F63.5 C11.0 P25. 5. Folk Ternary diagram of quartz, feldspar and rock fragments (QFR) illustrate that the range of these sandstones is from Q96.1F0.0R3..9 to Q100F0.0R0.0 with an average Q98F0.0R2..00 (Riyadah – 1) and Q96.0 F0.0 R4.0 to Q98F0.0R2.00with an average Q98.1F0.0R1.9 (Riyadah – 2).Undulosity and polycrystallinity point count data, and heavy suites were used as provenance indicators which suggest the medium and high rank metamorphism as dominant provenance with subordinate plutonic source and few low rank metamorphism. Two ratios, polycrystalline/monocrystalline quartz and undulose/ non-undulose quartz, successfully distinguish the two sandstone variety. Polycrystalline / monocrystalline ratios for Riyadh-1 & Riyadh-2 are very similar, 0.29 & 0.28 respectively. The ratio of undulose / non-undulose at Riyadh-1 & Riyadh-2 show clear difference, 0.34 & 0.60 respectively. These may lead to believe that the Riyadh-2 sandstones were originated from mix sources or had suffered rigorous thermodynamic diagenetic regime.Heavy mineral analysis offers a high-resolution approach to identify sandstone provenance, because of the diversity of mineral species found in sandstones.

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