Source: The Hindu
Manifest pedagogy: Dallol represents the region which is completely devoid of life. The physio-chemical conditions of such regions could be asked at preliminary stage. Brief preparation of the above helps in answering Science & Tech questions.
In news: Scientists recently discovered a place on earth which is devoid of any form of life.
Placing it in syllabus: Geothermal energy
- Dallol Geothermal Field
- Geographical location
- Its physio-chemical properties
Content: Geothermal energy is the heat derived within the sub-surface of the earth. Water and/or steam carry the geothermal energy to the Earth’s surface.
Dallol Geothermal Field:
- Scientists have discovered that hot, hyperacid ponds of Dallol Geothermal Field in Ethiopia and the nearby magnesium-filled salt pools have no life.
- The conditions here are so extreme that even microbes cannot adapt to survive.
- The importance of this finding is that it could help us understand the limits of habitability of life on Earth despite the presence of liquid water.
- This place has extreme conditions of heat (daily temperatures soar over 45 degrees Celsius even in winters) and dryness that the study experts have proposed it as a terrestrial analogue of early Mars.
- It is also one of the lowest land points on Earth which lies 410 feet below the mean sea level.
Its geographical location:
- Dallol lies in the evaporitic plain of the Danakil depression at the Afar Triangle.
- It lies in the prolongation of the Erta Ale basaltic volcanic range.
- The intrusion of basaltic magma in the marine sedimentary sequence of Danakil resulted in the formation of a salt dome structure, where the hydrothermal system is hosted.
- The wider area of Dallol is known as one of the driest and hottest places on the planet.
- Other known hydrothermal features nearby Dallol are Yellow and Black Lakes.
- Earlier findings had shown that microorganisms cannot survive in the magnesium-rich Black and Yellow lakes.
Physio-chemical properties of Dallol field:
- The hydrothermal springs of Dallol discharge anoxic, hyper-acidic, hyper-saline (almost 10 times more saline than seawater), high temperature brines that contain more than 26 g/L of iron.
- The pH scale measurements even reach negative readings at times.
- The main gas phases emitted from the springs are CO2, H2S, N2, SO2 and traces of H2, Ar, and O2.
- The coexistence of such extreme physicochemical characteristics has left Dallol to be one of the very few ‘poly-extreme’ sites on Earth.
- Parts of the region are nearly sterile, except for a diverse array of “ultrasmall” archaea.
- In contrast to other hydrothermal systems known for their colorful pools (e.g. Yellowstone), where the colors are generated by biological activity, the color palette of Dallol is produced by the inorganic oxidation of the abundant iron phases.
- It has a wide array of unusual mineral patterns like salt-pillars, miniature geysers, water-lilies, flower-like crystals, egg-shaped crusts, and pearl-like spheres.