Abstract
Dallol area is located in Afar region of northeastern Ethiopia. From west to east, the geology of the area is characterized by: i) Neoproterozoic metavolcanics and metasediments, ii) Quaternary alluvial fan deposits and red beds, iii) a transitional zone of mud and salt mixture, and iv) evaporites, which consist of rock salt (commonly halite and potash) and sulfur/sulfides. The metavolcanic-sedimentary rocks of the area are sheared and locally affected by pervasive chloritization, silicification, and carbonatization as well as quartz-carbonate veining suggesting that it has a good potential for orogenic gold mineralization. The around 5 m thick alluvial sediments of Gehartu and Musely Fans are also favorable for the occurrence of placer gold deposits. This study reveals that industrial minerals such as kaolin and mica are also encountered in the Dallol area in addition to the already known sulfur and salt deposits. In surrounding areas of mount Dallol, hot springs of varying temperature and extent are being erupted forming semicircular to circular ponds. In this study, two types of hot springs, light-yellowish and yellowish brines are recognized which are contaminated with mud. Field observations show that both brines have indications for the presence of oil as sensed by greasy feelings. To know the general compositions of the hot springs and test the presence of liquid hydrocarbons, 8 water samples were collected and analyzed for major element contents, sulfide, sulfate and Total Organic Carbon (TOC) concentrations. The preliminary results show that TOC values are moderately low (94 to 902 ppm). Sulfate (19 to 60 ppm) and sulfide (27 to 111 ppm) concentrations are low except for one sample with higher concentrations for both complexes. Their low sulfide and sulfate content suggest that these compounds are converted into sulfur/sulfide by bacterial reduction of magmatic and/or sea water SO2 or sulfate. Therefore, the Dallol hot springs are interpreted to be derived from heated groundwater mixed with sulfides/sulfates of magmatic and/or sea water origin. Although low, the up to 902 ppm TOC concentrations in the hydrothermal fluids could suggest the presence of hydrocarbon containing rocks at depth and/or fluid mixing with laterally and/or vertically migrating hydrocarbon fluids. Generally, the Dallol area contains huge metallic and non metallic resources, which warrant detailed exploration and further scientific study.
Highlights
Located in Afar Regional State, northeastern Ethiopia, Dallol area represents the second lowest water uncovered oceanic crust on Earth with a depth of ~120 m below sea level
This paper presents an overview of the geology and mineral potential of the region, nature and characteristics of the hot springs, which were observed and sampled during field excursions in and around Dallol organized by Mekelle University with an objective of assessing its natural resources potential. 1.1
The geology of the area is characterized by: (i) Neoproterozoic metavolcanic and metasedimentary rocks, (iii) gently dipping Quaternary alluvial deposits intercalated with red beds, and (iv) evaporites, which mainly consists of salt deposits and sulfur especially on mount Dallol and its vicinities (Fig. 2)
Summary
Located in Afar Regional State, northeastern Ethiopia, Dallol area represents the second lowest water uncovered oceanic crust on Earth with a depth of ~120 m below sea level ( reference missing Fig.). In addition to the salt resources, hot springs are continuously erupting at different spots of mount Dallol and its surroundings by forming circular to sub circular ponds. They are becoming tourist destinations for visitors from all over the world. Accessibility and physiography The Dallol area is located about 200 km NE of Mekelle, in Afar Regional State, northeastern Ethiopia (Fig. 1). Dallol region is very sparsely populated by the Afar people who are nomads and pastoralists Their main means of living is livestock production and traditional salt mining
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