Date of Award

12-2001

Document Type

Thesis

Degree Name

Master of Science (MS)

Department

Environmental Science

First Advisor

Mohammed Abu - Zeid

Second Advisor

Dr. Mamdouh Shebl

Third Advisor

Dr. V. Balasubramaniam

Abstract

Combined microscopic, heavy mineral, X-ray diffraction and chemical analyses have been carried out on the Jurassic limestone, the upper cretaceous Hawasina cherts and the coastal and inland sand dunes in several localities in the Ras Al Khaimah Emirate. The obtained results revealed that a number of represents cherts subfacies; namely: ferruginous radiolarian ribbon chert, carbonaceous radiolarian ribbon chert, colloform ribbon chert, calcareous chert and siliceous mud stone. These rocks consist of (in order of decreasing abundance): quartz, calcite, dolomite and hematite. The carbonate rocks are made up of lime mudstone, wackestone; pack stone and, rarely, crystalline limestone. Various types of wackestone and pack stone were recorded. Mineral1ogically, these limestone consist of calcite and much lesser proportions of quartz and dolomite. Diagenesis greatly modified the original textural and compositional characteristics of the rocks especially the limestone. On the other hand, the light fractions of the coastal sand dunes contain higher concentrations of carbonate lithoclasts and skeletal grains and lower proportions of quartz and chert than those of the inland dunes. Also, the heavy fractions of the former sediments are slightly more enriched in opaques, pyroxenes, epidotes and hornblende while depleted in rutile, tourmaline, garnet and monazite.

The obtained geochemical data confirm the presence of the main chert types; namely: (i) radiolarites (R), (ii) calcareous cherts (CC), and (iii) siliceous mudstones(SM). Each type has a homogeneous and characteristics major and trace element confirmed by the increase of Ti02, Al2O3), MgO, Fe203) and HFSE ( High Field Strength Elements). The cherts exhibit LREE (Light Rare Earth Elements) fractionated patterns with moderate negative Eu anomalies. R-mode cluster analysis shows three clusters. The first is for the carbonate minerals the second includes the terrigenous components and the third is the silica cluster. Factor analysis produced a two-factor model, which accounts for 85.85% of the data variability. The first is the terrigenous factor (Ti02,Al2O3) FeO, K20, P205 Rb, Ga, Zr and REE), and the second is the carbonate factor.

The majority of the studied limestones and a few of the chert rocks are

Compositionally similar to those presently used by the Ras Ai Khaimah Rock Company for cement

Production and, consequently can be considered for possible future needs. On the other hand, the compositional characteristics of the dune sands, especially the coastal dunes, do not permit their use as a possible source of silica.

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