MINERALOGY OF COPPER DEPOSITS AND ANCIENT SLAGS AT THE VICINITY OF JABAL SAMRAN ARC METAVOLCANICS, WESTERN CENTRAL SAUDI ARABIA | ||
| Delta Journal of Science | ||
| Article 12, Volume 31, Issue 1, June 2007, Pages 146-173 PDF (4.81 M) | ||
| Document Type: Research and Reference | ||
| DOI: 10.21608/djs.2007.153127 | ||
| Author | ||
| Talal Moustafa Qadi | ||
| Department of Mineral Resources and Rocks, Faculty of Earth Sciences, King Abdulaziz University, p. o. Box 80206, Jeddah 21589, Saudi Arabia | ||
| Abstract | ||
| Secondary copper mineralizations at Jabal Samran area are located essentially in the form of a NE-trending shear zone characterized by hydrothermally altered metadacite formed in Precambrian arc setting. The disseminated sulphides in the metavolcanics host might also played an important role in the genesis of secondary copper mineralization that are confined to the shear zone. Hence, it is suggested that seawater and/or magmatic water were circulating and then emanated into the sea floor along deep-seated fractures forming an oxidizing hydrothermal cell rich in Co2. The movement of such hydrothermal fluids was responsible for dissolution of the Cu-bearing disseminated sulphides and the formation of contemporaneous extensive alteration zone in the underlying metadacites and to lesser extent in the metatuffs. It is believed here the formation of paratacamite by Cl-rich seawater oxidation of primary sulphides on the seafloor. It is believed that albitization and silicification of the host metavolcanics at Jabal Samran, mostly metadacite, promoted a type of acid neutralizing hydrolysis reactions at low pH leading to the formation of hydrous Cu-phases, chrysocolla and paratacamite. The mineralogical investigation of Samran copper slags revealed that the badly processed native copper prills still preserve relict chalcocite which is here considered as the main copper ore used by the ancients (the Abbasiyeen in particular) in addition to paratacamite, brochantite and other S-bearing phases (e.g. barite and jarosite).A mixture of copper ore minerals and two different types of fluxes (calcium carbonate and hematite) in order to lower the fluxing temperature of copper. Some of the collected slags still preserve relics of charcoal that acted as the source of energy. The copper slags of Jabal Samran area are air-cooled slags which are supported by the rope-like surface. | ||
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