User:Rachelso2020/Dallol: Difference between revisions

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Much research has been conducted over the past two decades about the geology (e.g. formations, volcanic activity, seismicity) of the Dallol region.<ref name= Hovland>[https://www-sciencedirect-com.ezproxy.galter.northwestern.edu/science/article/pii/S0264817206000882?via%3Dihub Hovland, M., Rueslatten, H. G., Johnsen, H. K., Kvamme, B., & Kuznetsova, T. (2006). Salt formation associated with sub-surface boiling and supercritical water. Marine and Petroleum Geology, 23(8), 855-869. Article.]</ref><ref name= Carniel>[https://www-sciencedirect-com.ezproxy.galter.northwestern.edu/science/article/pii/S1464343X10000257?via%3Dihub Carniel, R., Jolis, E. M., & Jones, J. (2010). A geophysical multi-parametric analysis of hydrothermal activity at Dallol, Ethiopia. Journal of African Earth Sciences, 58(5), 812-819. Article.]</ref><ref name= Hagos>[https://www.ajol.info/index.php/mejs/article/view/134809 Hagos, M., Konka, B., & Ahmed, J. (2016). A preliminary Geological and Generalized Stratigraphy of Western Margin of Northern Afar Depression, Dallol Area, Northern Ethiopia. Momona Ethiopian Journal of Science, 8(1), 1-22. Article.]</ref> However, studies on the diversity of life at Dallol have only been published over the past few years. Until recently, it was believed that Dallol hosted conditions too harsh for life.<ref name= Kotopoulou/>  
Much research has been conducted over the past two decades about the geology (e.g. formations, volcanic activity, seismicity) of the Dallol region.<ref name= Hovland>[https://www-sciencedirect-com.ezproxy.galter.northwestern.edu/science/article/pii/S0264817206000882?via%3Dihub Hovland, M., Rueslatten, H. G., Johnsen, H. K., Kvamme, B., & Kuznetsova, T. (2006). Salt formation associated with sub-surface boiling and supercritical water. Marine and Petroleum Geology, 23(8), 855-869. Article.]</ref><ref name= Carniel>[https://www-sciencedirect-com.ezproxy.galter.northwestern.edu/science/article/pii/S1464343X10000257?via%3Dihub Carniel, R., Jolis, E. M., & Jones, J. (2010). A geophysical multi-parametric analysis of hydrothermal activity at Dallol, Ethiopia. Journal of African Earth Sciences, 58(5), 812-819. Article.]</ref><ref name= Hagos>[https://www.ajol.info/index.php/mejs/article/view/134809 Hagos, M., Konka, B., & Ahmed, J. (2016). A preliminary Geological and Generalized Stratigraphy of Western Margin of Northern Afar Depression, Dallol Area, Northern Ethiopia. Momona Ethiopian Journal of Science, 8(1), 1-22. Article.]</ref> However, studies on the diversity of life at Dallol have only been published over the past few years. Until recently, it was believed that Dallol hosted conditions too harsh for life.<ref name= Kotopoulou/> New research using next generation sequencing and biomarker analysis suggests that microbial life is indeed present though their spatial distribution and general abundance is relatively low.<ref name= Belilla/> Belilla et al. identified diverse archaeal and bacterial phyla at certain sites in the Dallol geothermal system.<ref name= Belilla/> Water and geological samples were collected from the Dallol dome pools, adjacent salt plains, Black Lake, Lake Gaet'ale, and Lake Assale (30 km south of the dome), but sequencing and culturing only found evidence of microbes in the salt plain samples and in Lake Assale.
 
Diverse microbial phyla have been detected living in the Dallol hydrothermal system though research thus far suggests their spatial distribution is limited and their general abundance is low. A study of water and sinter deposit samples collected from the Dallol dome pools, adjacent salt plains, Black Lake, Lake Gaet'ale, and Lake Assale (30 km south of the dome) found evidence of life only in the salt plain samples and in Lake Assale.<ref name= Belilla/>


==Volcanic Evolution==
==Volcanic Evolution==

Revision as of 07:38, 29 May 2020

Dallol Hydrothermal System

Overview

Pools and terraces of the Dallol hydrothermal system.[1]

By Rachel So

(Introduce environment. Give key information relevant to the microbial ecology of the environment.)

The Dallol hydrothermal system is located in the northern part of the Danakil Depression in the Afar Triangle (also called Afar triple junction or Afar Depression) of northeastern Ethiopia.[1][2] Dallol is a desert that receives less than 200 mm of rainfall a year and holds the record as the hottest location on the planet (mean annual temperature of 34.5°C).[3][4] Its hydrothermal pools form a unique hyperthermal (25-110°C), hypersaline (33% to > 50% salinity), and hyperacidic (pH < -1.5 to 6.0) polyextreme environment that pushes the limits of life.[5] In addition, the pools contain high concentrations of chlorides, sulfates, and dissolved iron (both Fe2+ and Fe3+), the last giving them their colorful appearance.[1]

About the Environment

(Describe the physical and geochemical environment that you are reporting on. How well is has this been studied? Is it current or is most of the work from the 80s? What are the geochemical characteristics? Include some current research, with at least one figure showing data.)

(map of Dallol geographic region, any)

Located at the junction of the Nubian, Somali, and Arabian plates, the Danakil Depression is part of the East African Rift system and experiences high tectonic and geothermal activity.[3][6] The Depression exists at the northern end of a line of Holocene-age active volcanoes that run north-northwest to south-southeast.[3] While not a proper volcano itself, its physical appearance, geothermal activity, and location along this volcanic range has caused the Dallol dome (within the Depression) to sometimes be referred to as the "Dallol volcano" or "Dallol protovolcano".[1][3] Despite its occasional designation as a volcano, the Dallol dome does not experience eruptions or have volcanic outcrops.[5]


The Danakil Depression is approximately 120 m below sea level with the Dallol dome rising up about 40 m from the Depression. [5] The area around the dome is a vast salt plain composed of 2 km thick evaporites (enriched in potassium, manganese, iron, magnesium, and zinc) deposited by repeated transgressions of the Red Sea.[1][7] The continental crust at Danakil is less than 15 km thick, a result of variable rifting over much of the Afar region.[6] A large variety of hydro-geothermal features are found at Dallol including hydrothermal springs, brine pools, geysers, and salt chimneys, pillars, and terraces.[1] These features are formed from evaporation of supersaturated brines and are highly dynamic.[1] The number of active springs changes year to year and some pools appear and disappear over periods of days to weeks.[1][6] A number of unique precipitate formations have also been recorded including, but not limited to, flower-like structures, eggshell-like structures, spherules, and thick crusts cracked into polygons.[1]


Due to the area's heterogeneity, water samples collected from Dallol vary in temperature, pH, salinity, and solute composition and concentrations. Though temperatures over 50°C, pH < 0, and salinities over 30% are common.[1][5][6] Several locations within the Dallol hydrothermal system have been studied including the hot springs and pools of the Dallol dome, Gaet'ale Lake (also called Yellow Lake) 4 km southeast of the dome, and Black Lake less than 2.5 km southwest of the dome.[1][2][5][6] At the dome hot springs, the anoxic, hyperacidic, iron-rich source water from vents had recorded temperatures of 105-108°C.[1] As the water emerges, the temperature quickly decreases causing supersaturation and rapid halite precipitation. The water flows into pools, moving progressively further away from the spring, falling to temperatures of around 30°C. These waters have pH values of 0 or lower and salinities ranging from 37%-42%.[1][5]


(image of colorful Dallol water samples in glass bottles, Belilla)
(image of green Dallol pools w/ temp and pH, Kotopoulou)

A well-known feature of the Dallol pools is their bright colors including shades of greens, blues, yellows, and browns.These colors have been attributed mainly to iron redox chemistry. High concentrations of dissolved iron (22.5 g/L), sulfates (~5200 ppm), and chlorides (>200 g/L) contribute to the formation of colorful iron hydroxo-complexes, iron chloro-complexes, and iron sulfates. Spring water start out with high concentrations of ferrous iron (Fe2+) that is slowly oxidized (as the water equilibrates with the atmosphere) to ferric iron (Fe3+), causing pool waters to move from bright green to dark green to brown. Outside the water, thin layers of precipitated iron-(oxy)hydroxides and iron sulfates over the halite structure give them a similarly colorful appearance.[1]


While the age of the Dallol Dome is not known, Black Lake and Gaet'ale Lake appeared after phreatic explosions in 1926 and 2005, respectively.[1] For Black Lake, Cavalazzi et al. recorded an average temperature of 56°C and a pH of 1.4.[6] Belilla et al. found slightly milder conditions at 40°C and a pH of 3 along with salinities of 35-60%.[5] For Gaet'ale Lake, a temperature of 55°C and a pH of 3 were measured by the former, while 40°C and pH 1.8 were recorded by the latter (as well as salinities ≥ 50%).[6][5] Both lakes contain high concentrations of calcium (Ca2+) and magnesium (Mg2+) (particularly magnesium chloride), and Gaet'ale Lake continuously bubbles up toxic gas.[5]

Dallol Microbial Ecology

(Discuss the alpha and beta diversity of the system. Include some current research, with at least one figure showing data.)

Much research has been conducted over the past two decades about the geology (e.g. formations, volcanic activity, seismicity) of the Dallol region.[8][9][10] However, studies on the diversity of life at Dallol have only been published over the past few years. Until recently, it was believed that Dallol hosted conditions too harsh for life.[1] New research using next generation sequencing and biomarker analysis suggests that microbial life is indeed present though their spatial distribution and general abundance is relatively low.[5] Belilla et al. identified diverse archaeal and bacterial phyla at certain sites in the Dallol geothermal system.[5] Water and geological samples were collected from the Dallol dome pools, adjacent salt plains, Black Lake, Lake Gaet'ale, and Lake Assale (30 km south of the dome), but sequencing and culturing only found evidence of microbes in the salt plain samples and in Lake Assale.

Volcanic Evolution

(How you expand upon the basics will depend on your environment. Pick a couple or three of interesting subtopics and describe them in detail. Include some current research, with at least one figure showing data.)


Analog for Extraterrestrial Environments

The Dallol hydrothermal system has been proposed as an analogue for the environment of Mars.[6]

Anthropological Significance


Key Microbial Players

In all of your systems there will be at least a couple of key microbial players. Describe these in detail. Where do they fall on the tree of life? Are they cultured? What do they do in general and as it relates to your target environment?

Conclusion

References

  1. ↑ 1.00 1.01 1.02 1.03 1.04 1.05 1.06 1.07 1.08 1.09 1.10 1.11 1.12 1.13 1.14 1.15 Kotopoulou, E., Huertas, A. D., Garcia-Ruiz, J. M., Dominguez-Vera, J. M., Lopez-Garcia, J. M., Guerra-Tschuschke, I., & Rull, F. (2019). A Polyextreme Hydrothermal System Controlled by Iron: The Case of Dallol at the Afar Triangle. Acs Earth and Space Chemistry, 3(1), 90-99. Article.
  2. ↑ 2.0 2.1 Gomez, F., Cavalazzi, B., Rodriguez, N., Amils, R., Ori, G. G., Olsson-Francis, K., et al. (2019). Ultra-small microorganisms in the polyextreme conditions of the Dallol volcano, Northern Afar, Ethiopia. Scientific Reports, 9, 9. Article.
  3. ↑ 3.0 3.1 3.2 3.3 Lopez-Garcia, J. M., Moreira, D., Benzerara, K., Grunewald, O., & Lopez-Garcia, P. (2020). Origin and Evolution of the Halo-Volcanic Complex of Dallol: Proto-Volcanism in Northern Afar (Ethiopia). Frontiers in Earth Science, 7, 24. Article.
  4. ↑ Pedgley, D. E. (1967). AIR TEMPERATURE AT DALLOL ETHIOPIA. Meteorological Magazine, 96(1142), 265-&. Article.
  5. ↑ 5.00 5.01 5.02 5.03 5.04 5.05 5.06 5.07 5.08 5.09 5.10 Belilla, J., Moreira, D., Jardillier, L., Reboul, G., Benzerara, K., Lopez-Garcia, J. M., et al. (2019). Hyperdiverse archaea near life limits at the polyextreme geothermal Dallol area. Nature Ecology & Evolution, 3(11), 1552-+. Article.
  6. ↑ 6.0 6.1 6.2 6.3 6.4 6.5 6.6 6.7 Cavalazzi, B., Barbieri, R., Gomez, F., Capaccioni, B., Olsson-Francis, K., Pondrelli, M., et al. (2019). The Dallol Geothermal Area, Northern Afar (Ethiopia)-An Exceptional Planetary Field Analog on Earth. Astrobiology, 19(4), 553-578. Review.
  7. ↑ Tadesse, S., Milesi, J. P., & Deschamps, Y. (2003). Geology and mineral potential of Ethiopia: a note on geology and mineral map of Ethiopia. Journal of African Earth Sciences, 36(4), 273-313. Article.
  8. ↑ Hovland, M., Rueslatten, H. G., Johnsen, H. K., Kvamme, B., & Kuznetsova, T. (2006). Salt formation associated with sub-surface boiling and supercritical water. Marine and Petroleum Geology, 23(8), 855-869. Article.
  9. ↑ Carniel, R., Jolis, E. M., & Jones, J. (2010). A geophysical multi-parametric analysis of hydrothermal activity at Dallol, Ethiopia. Journal of African Earth Sciences, 58(5), 812-819. Article.
  10. ↑ Hagos, M., Konka, B., & Ahmed, J. (2016). A preliminary Geological and Generalized Stratigraphy of Western Margin of Northern Afar Depression, Dallol Area, Northern Ethiopia. Momona Ethiopian Journal of Science, 8(1), 1-22. Article.



Authored for Earth 373 Microbial Ecology, taught by Magdalena Osburn, 2020, NU Earth Page.

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