26 December 2016

Publication in Nature Geoscience

Hidden rivers form deep down in the Earth’s subsurface layers

Earth scientists from among others Utrecht University and the Free University of Berlin have found new clues how water moves inside the Earth’s deep subsurface layers and ultimately back to the surface through volcanic activity. They published their results in the journal Nature Geoscience on 26 December 2016.

Two water cycles

Planet Earth has two water cycles. The first one involves our oceans, with cloud formation through evaporation resulting in rain on land and ultimately drainage back to the ocean, often through rivers. However, in the deep hidden layers of the Earth there is another cycle and up to this point the water flow of this second cycle was poorly understood.

Plates take water along

Within the Earth’s tectonic plates water molecules are trapped into the rock forming minerals of various chemical compositions. In areas where the plates collide one plate moves underneath the other one and sinks down into the mantle taking along the water molecules inside it. Without a chemical and physical mechanism whereby water gets returned to the Earth’s surface it is estimated that the oceans would get depleted in potentially 1.5 billion years. But as we can observe everyday this doesn’t happen.

An interdisciplinary team of scientists studied ancient rocks found in Italy in a quest to further understand Earth’s second inner water cycle.

Complex patterns of channels inside the rock on a scale of meters (left), centimeters (middle) and nanometers (right).

Hidden rivers

Oliver Plümper, researcher at Utrecht University and lead author of the paper, said: “Using state-of-the-art rock analysis, and advanced numerical modelling we were able to demonstrate a complex pattern of channels inside the rock. From nanoscale up to meters long we saw clear channels that form at the onset of water release, hence form surprisingly quickly. These channels resemble hidden river systems that move water along through the solid Earth interior and ultimately join up into big upward channels with water being pushed out again to the Earth’s surface often through volcanic activity.” Timm John, researcher at Free University of Berlin continued: “Previous concepts of Earth’s deep water cycle typically assume that water slowly moves throughout the entire rock without forming channels, but this is obviously not the case.”

The findings were published in the journal Nature Geoscience on 26 December 2016 by a team of researchers based at Utrecht University, Free University of Berlin, University of Lausanne, and the University of Genoa.

Publication details

Plümper O, John T, Podladchikov YY, Vrijmoed JC and Scambelluri M. 2016. Fluid escape from subduction zones controlled by channel-forming reactive porosity. Nature Geoscience. DOI: 10.1036/NGEO2865. Online publication date 26 December 2016.