1. Data‐Driven Investigation Reveals Subaerial Proportion of Basalts Since the Early Archean.
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Liu, Chun‐Tao, Liu, Xiao‐Ming, and ZhangZhou, J.
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MACHINE learning , *SUPERVISED learning , *ARCHAEAN , *BASALT , *SURFACE of the earth , *CONTINENTAL crust , *CONTINENTS - Abstract
The subaerial exposure of the modern continental crust through time remains intensely debated, with estimates of the first exposure ranging from the late Archean to the Neoproterozoic. To constrain when and how much of the continental crust was exposed subaerially during Earth's history, we trained a supervised machine learning model on the compositions of modern subaerial and submerged basalts. Then, we applied this well‐trained model to a refined worldwide data set of basaltic compositions and calculated the mean proportions of basalts erupted subaerially since 3.8 billion years ago (Ga). Our results suggest that ∼20% of the basalts were exposed subaerially in the early Archean, which may have driven the synthesis of biopolymers crucial to the origins and evolution of life. The proportion of subaerial basalts increased markedly during two stages between the late Archean and the Paleoproterozoic before reaching the present‐day level no earlier than ∼1.8 Ga. Plain Language Summary: Although land only covers about 30% of Earth's surface, it plays a crucial role in our planet's ecosystem by interacting with the ocean and atmosphere. Scientists are still debating when and how much land was above sea level throughout history. In our study, we used a machine learning technique to analyze the chemical compositions of basalts and classified rocks that formed on land and under water. We then used this program to study rocks from different times in Earth's history and estimate how much land was above the oceans over time. We found that about 15%–30% of the continents were above the oceans about 3.8 to 2.8 billion years ago (Ga). This may have helped life evolve by creating molecules essential for living things. The amount of land above water increased significantly during two periods between 2.8 and 1.8 Ga and reached today's level no earlier than 1.8 Ga. Key Points: Improve the geochemical data quality of global basaltic rocksMachine learning can effectively classify subaerially and subaqueously erupted basaltsThe subaerial proportion of basalts may reach present‐day level at about 1.8 billion years ago to a maximum [ABSTRACT FROM AUTHOR]
- Published
- 2024
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