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Cavalazzi B, Barbieri R, Gómez F, Capaccioni B, Olsson-Francis K, Pondrelli M, Rossi A, Hickman-Lewis K, Agangi A, Gasparotto G, Glamoclija M, Ori G, Rodriguez N, Hagos M. The Dallol Geothermal Area, Northern Afar (Ethiopia)-An Exceptional Planetary Field Analog on Earth. Astrobiology 2019; 19:553-578. [PMID: 30653331 PMCID: PMC6459281 DOI: 10.1089/ast.2018.1926] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/07/2023]
Abstract
The Dallol volcano and its associated hydrothermal field are located in a remote area of the northern Danakil Depression in Ethiopia, a region only recently appraised after decades of inaccessibility due to severe political instability and the absence of infrastructure. The region is notable for hosting environments at the very edge of natural physical-chemical extremities. It is surrounded by a wide, hyperarid salt plain and is one of the hottest (average annual temperatureDallol: 36-38°C) and most acidic natural systems (pHDallol ≈0) on Earth. Spectacular geomorphologies and mineral deposits produced by supersaturated hydrothermal waters and brines are the result of complex interactions between active and inactive hydrothermal alteration of the bedrock, sulfuric hot springs and pools, fumaroles and geysers, and recrystallization processes driven by hydrothermal waters, degassing, and rapid evaporation. The study of planetary field analog environments plays a crucial role in characterizing the physical and chemical boundaries within which life can exist on Earth and other planets. It is essential for the definition and assessment of the conditions of habitability on other planets, including the possibility for biosignature preservation and in situ testing of technologies for life detection. The Dallol area represents an excellent Mars analog environment given that the active volcanic environment, the associated diffuse hydrothermalism and hydrothermal alteration, and the vast acidic sulfate deposits are reminiscent of past hydrothermal activity on Mars. The work presented in this paper is an overview of the Dallol volcanic area and its hydrothermal field that integrates previous literature with observations and results obtained from field surveys and monitoring coupled with sample characterization. In so doing, we highlight its exceptional potential as a planetary field analog as well as a site for future astrobiological and exploration programs.
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Affiliation(s)
- B. Cavalazzi
- Dipartimento di Scienze Biologiche, Geologiche e Ambientali, Università di Bologna, Bologna, Italy
- Department of Geology, University of Johannesburg, Johannesburg, South Africa
- Address correspondence to: Barbara Cavalazzi, Dipartimento di Scienze Biologiche, Geologiche e Ambientali - BiGeA, Università di Bologna, Via Zamboni 67, I-40126 Bologna, Italy
| | - R. Barbieri
- Dipartimento di Scienze Biologiche, Geologiche e Ambientali, Università di Bologna, Bologna, Italy
| | - F. Gómez
- Centro de Astrobiologia and Instituto Nacional de Técnica Aeroespacial, Madrid, Spain
| | - B. Capaccioni
- Dipartimento di Scienze Biologiche, Geologiche e Ambientali, Università di Bologna, Bologna, Italy
| | - K. Olsson-Francis
- School of Environment, Earth and Ecosystem Sciences, The Open University, Milton Keynes, United Kingdom
| | - M. Pondrelli
- Int'l Research School of Planetary Sciences, Università d'Annunzio, Chieti Scalo, Italy
| | | | - K. Hickman-Lewis
- Dipartimento di Scienze Biologiche, Geologiche e Ambientali, Università di Bologna, Bologna, Italy
- CNRS Centre de Biophysique Moléculaire, Orléans, France
| | - A. Agangi
- Department of Geology, University of Johannesburg, Johannesburg, South Africa
| | - G. Gasparotto
- Dipartimento di Scienze Biologiche, Geologiche e Ambientali, Università di Bologna, Bologna, Italy
| | - M. Glamoclija
- Department of Earth and Environmental Sciences, Rutgers University, Newark, New Jersey, USA
| | - G.G. Ori
- Int'l Research School of Planetary Sciences, Università d'Annunzio, Chieti Scalo, Italy
| | - N. Rodriguez
- Centro de Astrobiologia and Instituto Nacional de Técnica Aeroespacial, Madrid, Spain
| | - M. Hagos
- Department of Earth Sciences, Mekelle University, Mekelle, Ethiopia
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