Careful monitoring by geologists of special types of active volcanoes known as supervolcanoes has shown that these volcanoes rise and lower in accordance with the magma moving below the surface of the earth. Magmas rich in silica like those in the Yellowstone region and also along the western margins of America often erupt suddenly and violently, causing huge amounts of ash to be hurled into the air, followed by lesser amounts of glassy magma.
Until now however we have not known what the actual magma chambers look like beneath the surface of the earth. Scientists from the University of Wyoming have suggested that it is possible to venture back into the past to study the artefacts from past volcanic explosions – notably the solid magma chambers that have been exposed due to erosion of the underlying rocks. And this is exactly the mission they funded.
The recently published study examined one of the oldest and most famous granite bodies – a huge 2.6 billion year old batholith located in Wyoming. Researchers examining this body were able to identify key magma chambers that give insights into how the active subterranean chambers must look like. In the words of researcher Carol Frost – “The present is the key to the past”, in reference to the geology of volcanos.
It was found after extensive chemical and isotopic analysis that the huge batholith had its magma form via the melting of multiple rock sources that rose via conduits. The more precise geological configuration of the rocks and their ores were examined. Such studies in the past of the remnants of supervolcanic eruptions have not been without controversy however, says Brad Singer from the Department of Geoscience, University of Winconsin-Madison. Singer states that the research conducted by Frost and her associates has given a unique, novel perspective of the Wyoming batholith that suggests the vast magma system may have fed active supervolcanos, such as those that have erupted in Chile over the past 10 million years, via its frozen portions. If this is indeed the case, the insights could be key to understanding the structure of the subterranean magma chambers.
Questions however have been raised if this is really the case. The Wyoming granites contain high amounts of potassium and silica that differ from the magma accumulations commonly found in Andean supervolcanoes. Whilst the research may give unique insights into the chambers in the Wyoming region, whether this would translate to other supervolcanoes is less certain. Nevertheless, the paper does provide some unique new insights into volcano subterranean connections.
Carol D. Frost, B. Ronald Frost, and James S. Beard.
“On silica-rich granitoids and their eruptive equivalents”.
American Mineralogist, June 2016