A group of geologists from Cuba, Colombia and the Netherlands conducted a study that challenged traditional ideas about mantle flows in the Earth's interior. The study was published in a press release on Phys.org.
Easter Island in the Pacific consists of several extinct volcanoes, the oldest of which formed about 2.5 million years ago. Scientists have discovered ancient zircon minerals up to 165 million years old, challenging the traditional idea that mantle flows move with tectonic plates like a conveyor belt. Chemical analysis of the zircon showed that all the minerals have a similar composition, suggesting a common origin from magma.
To date the volcanic rocks, the research team used a method to radioactively decay uranium into zircons, which form when magma crystallizes. Many zirconia were found, confirming the age of the formations. However, their presence in large quantities and such ancient age call into question the traditional volcanic models of the island. The study found that the mantle beneath Easter Island probably remained active for 165 million years, consistent with periods when other areas of the mantle may have been absorbed into subduction zones. A volcanic plateau that existed 165 million years ago may have been swallowed beneath the Antarctic Peninsula. This explains how ancient zircons can be preserved in young volcanic material.
The Easter Island discovery therefore suggests that the Earth's mantle behaves differently than previously thought and moves more slowly. This discovery may lead to a revision of existing models of mantle processes and expand our understanding of Earth's geological processes. | BGNES
