Composition of the Primordial Ocean Just after Its Formation: Constraints from the Reactions between the Primitive Crust and a Strongly Acidic, CO<sub>2</sub>-Rich Fluid at Elevated Temperatures and Pressures

The Hadean was an enigmatic period in the Earth’s history when ocean formation and the emergence of life may have occurred. However, minimal geological evidence is left from this period. To understand the primordial ocean’s composition, we focused on the ocean’s formation processes from CO<sub>...

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Main Authors: Hisahiro Ueda, Takazo Shibuya
Format: Article
Language:English
Published: MDPI AG 2021-04-01
Series:Minerals
Subjects:
Online Access:https://www.mdpi.com/2075-163X/11/4/389
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spelling doaj-bd44cf25c45c48a0aa65a4a79d19cbdb2021-04-06T23:00:47ZengMDPI AGMinerals2075-163X2021-04-011138938910.3390/min11040389Composition of the Primordial Ocean Just after Its Formation: Constraints from the Reactions between the Primitive Crust and a Strongly Acidic, CO<sub>2</sub>-Rich Fluid at Elevated Temperatures and PressuresHisahiro Ueda0Takazo Shibuya1Super-Cutting-Edge Grand and Advanced Research (SUGAR) Program, Institute for Extra-Cutting-Edge Science and Technology Avant-Garde Research (X-Star), Japan Agency for Marine-Earth Science and Technology (JAMSTEC), 2-15, Natsushima-cho, Yokosuka 237-0061, JapanSuper-Cutting-Edge Grand and Advanced Research (SUGAR) Program, Institute for Extra-Cutting-Edge Science and Technology Avant-Garde Research (X-Star), Japan Agency for Marine-Earth Science and Technology (JAMSTEC), 2-15, Natsushima-cho, Yokosuka 237-0061, JapanThe Hadean was an enigmatic period in the Earth’s history when ocean formation and the emergence of life may have occurred. However, minimal geological evidence is left from this period. To understand the primordial ocean’s composition, we focused on the ocean’s formation processes from CO<sub>2</sub>- and HCl-bearing water vapor in the high-temperature atmosphere. When the temperature of the lower atmosphere fell below the critical point, high-temperature rain reached the ground surface. Then, hydrothermal reactions between the subcritical fluid and primordial crust started. Eventually, a liquid ocean emerged on the completely altered crust as the temperature decreased to approximately 25 °C. Here, we conducted two experiments and modeling to simulate the reactions of hypothetical primordial crustal rock (basalt or komatiite). The results indicate that the primordial ocean was mildly acidic and rich in CO<sub>2</sub>, Mg, and Ca relative to Na, irrespective of the rock type, which is different from the modern equivalents. Therefore, unlike the present seawater, the primordial seawater could have been carbonic, bitter, and harsh rather than salty.https://www.mdpi.com/2075-163X/11/4/389ocean formationprimordial ocean compositionwater–rock reactionsHadeanexperimentthermodynamic calculation
collection DOAJ
language English
format Article
sources DOAJ
author Hisahiro Ueda
Takazo Shibuya
spellingShingle Hisahiro Ueda
Takazo Shibuya
Composition of the Primordial Ocean Just after Its Formation: Constraints from the Reactions between the Primitive Crust and a Strongly Acidic, CO<sub>2</sub>-Rich Fluid at Elevated Temperatures and Pressures
Minerals
ocean formation
primordial ocean composition
water–rock reactions
Hadean
experiment
thermodynamic calculation
author_facet Hisahiro Ueda
Takazo Shibuya
author_sort Hisahiro Ueda
title Composition of the Primordial Ocean Just after Its Formation: Constraints from the Reactions between the Primitive Crust and a Strongly Acidic, CO<sub>2</sub>-Rich Fluid at Elevated Temperatures and Pressures
title_short Composition of the Primordial Ocean Just after Its Formation: Constraints from the Reactions between the Primitive Crust and a Strongly Acidic, CO<sub>2</sub>-Rich Fluid at Elevated Temperatures and Pressures
title_full Composition of the Primordial Ocean Just after Its Formation: Constraints from the Reactions between the Primitive Crust and a Strongly Acidic, CO<sub>2</sub>-Rich Fluid at Elevated Temperatures and Pressures
title_fullStr Composition of the Primordial Ocean Just after Its Formation: Constraints from the Reactions between the Primitive Crust and a Strongly Acidic, CO<sub>2</sub>-Rich Fluid at Elevated Temperatures and Pressures
title_full_unstemmed Composition of the Primordial Ocean Just after Its Formation: Constraints from the Reactions between the Primitive Crust and a Strongly Acidic, CO<sub>2</sub>-Rich Fluid at Elevated Temperatures and Pressures
title_sort composition of the primordial ocean just after its formation: constraints from the reactions between the primitive crust and a strongly acidic, co<sub>2</sub>-rich fluid at elevated temperatures and pressures
publisher MDPI AG
series Minerals
issn 2075-163X
publishDate 2021-04-01
description The Hadean was an enigmatic period in the Earth’s history when ocean formation and the emergence of life may have occurred. However, minimal geological evidence is left from this period. To understand the primordial ocean’s composition, we focused on the ocean’s formation processes from CO<sub>2</sub>- and HCl-bearing water vapor in the high-temperature atmosphere. When the temperature of the lower atmosphere fell below the critical point, high-temperature rain reached the ground surface. Then, hydrothermal reactions between the subcritical fluid and primordial crust started. Eventually, a liquid ocean emerged on the completely altered crust as the temperature decreased to approximately 25 °C. Here, we conducted two experiments and modeling to simulate the reactions of hypothetical primordial crustal rock (basalt or komatiite). The results indicate that the primordial ocean was mildly acidic and rich in CO<sub>2</sub>, Mg, and Ca relative to Na, irrespective of the rock type, which is different from the modern equivalents. Therefore, unlike the present seawater, the primordial seawater could have been carbonic, bitter, and harsh rather than salty.
topic ocean formation
primordial ocean composition
water–rock reactions
Hadean
experiment
thermodynamic calculation
url https://www.mdpi.com/2075-163X/11/4/389
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AT takazoshibuya compositionoftheprimordialoceanjustafteritsformationconstraintsfromthereactionsbetweentheprimitivecrustandastronglyacidiccosub2subrichfluidatelevatedtemperaturesandpressures
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