SILICIFICATION IN THE RUS AND DAMMAM FORMATIONS IN SAMAWA AREA, SOUTHERN IRAQ | ||
| Iraqi Bulletin of Geology and Mining | ||
| Article 1, Volume 12, Issue 3, December 2016, Pages 11-25 | ||
| Authors | ||
| Basma A. Al-Samarraie; ; a Ph. Basher | ||
| Abstract | ||
| Various diagenetic processes have affected the Rus and Dammam Formations of Eocene age. These include dolomitization, dedolomitization, neomorphism, micritization, dissolution, cementation and silicification. In the present study the prominent and distinguished diagenetic process that influenced the rocks of the studied boreholes is the silicification. The petrographic examinations confirm the presence of three main types of silicification including selective, pervasive and minor. The selective silicification is the most common type in the Rus Formation as pore- filling cement after dissolution of sulfates while in the Dammam Formation occurs primarily as replacement material and as late diagenetic void-filling quartz. The pervasive silicification occurs within the Dammam Formation particularly in the middle part where both matrix and bioclasts are completely silicified. Minor silicification only affects echinoderm plates in the Dammam Formation. The petrographic study of the subsurface rocks show that the silicification of the Rus Formation and few rocks of the Dammam Formation occur in meteoric environments as the silica replaced sulfates while the silicification of the Dammam Formation occur within a mixs zone environment where meteoric water, which is the carrier of silica, mixed with marine water producing a solution supersaturated with silica and undersaturated in calcite. | ||
| Keywords | ||
| Silicification; Rus; Dammam; Carbonate Rocks; Iraq | ||
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