The same process today is happening every hour and everywhere under midocean ridges and also on continents. "They are now uplifted and eroded to the level that allows us to sample the contacts of these basalts with the previous rocks. "The Columbia River basalts that are so dear to us in the Pacific Northwest," Bindeman said. "We found that when hot basaltic magma intruded into the crust it boiled groundwater and volatilized everything in and near its path, causing chemical and isotopic changes in the rocks and the release of greenhouse gases," said Ilya Bindeman, a professor in the Department of Earth Sciences, who led the study.Ĭollectively, the effects of the heating throughout the flood-basalt region may have lasted about 150 years after magma stopped flowing, building the landscape that is visible today across the region, the seven-member research team from three countries concluded. It formed one of the largest surface lava flows and chemically altered about 100 meters of surrounding bedrock. A 10-meter-thick feeder dike into the Wallowa batholith, formed from a mix of basaltic magma and granite 16 million years ago, for example, likely acted as a magma conduit for up to seven years. Pivotal to the research were 27 samples from 22 different dikes - wall-like bodies of magma that cut through the sheeted lava flow landscape during the eruptions. It covers roughly 210,000 square kilometers, extending from eastern Oregon and Washington to western Idaho and part of northern Nevada. The Columbia River Flood Basalts represent the youngest continental flood basalt province on Earth and one of the best preserved. The insights, published in Scientific Reports, were drawn from analyses of oxygen and hydrogen isotopes in crustal material, a mix of magma and original rocks, that is now exposed by geological uplifting and erosion.
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