Solar radiation may have an impact on Earth's deep interior, according to a collaborative study by researchers from China and Romania.

The study, published in the journal Nature Communications, was conducted by the researchers from the Institute of Geology and Geophysics (IGG) at the Chinese Academy of Sciences, China University of Geosciences, and the University of Bucharest.

According to the researchers, solar radiation varies with latitude, creating temperature gradients on the sea surface that influence the distribution of marine life. These organisms, rich in carbon, are transported into Earth's interior through the subduction of oceanic plates. This process significantly affects the redox state of arc magma.

The researchers analyzed data from thousands of magma samples, including those from deep within the earth and the sea, collected by geologists worldwide. They examined tiny melt inclusions within olivine minerals and bulk rock data to determine the redox state of arc magma.

The study revealed that magma in lower latitude regions is less oxidized than in higher latitude areas. Additional evidence from ocean floor studies showed more reduced carbon deposits in lower latitudes. This carbon interacts with sulfur to form sulfide, which is then transported into the mantle, contributing to the observed redox pattern.

"This unexpected pattern suggests that the Earth's surface environment and climate, influenced by solar radiation, have a profound effect on mantle processes," said Wan Bo, co-author of the study and a researcher at IGG.

Many metal ores, such as copper, tin and lithium, are sensitive to redox conditions. Understanding the spatial and temporal distribution of redox state at global subduction zones has significant implications for predicting the locations and availability of these critical resources.

"The observed pattern offers new directions for exploring resources and understanding the environmental effects of subduction systems at different latitudes," said Hu Fangyang, the corresponding author of the study and a researcher at IGG.