5/30/2023 0 Comments Determining the age of waterMcIntosh leads the lab that conducted the research, and she co-authored the paper with Kim and Grant Ferguson, an adjunct faculty member in the Department of Hydrology and Atmospheric Sciences. "No one has ever tried to date the timescales of this process using groundwater before this paper." "Since then, groundwater recharge and circulation has been relatively shallow, until about 6 million years ago when the Colorado River started to cut into the landscape and allowed deep circulation of recharge from rain and snow," said Jennifer McIntosh, a professor in the Department Hydrology and Atmospheric Sciences. As the seawater receded, it left behind lagoons, which evaporated and left behind a thick salt layer and super salty seawater called brine. The sediments of the Paradox Basin were deposited 200 million to 300 million years ago when an ocean still existed in the region. About midway down the basin, they discovered ancient seawater from the Paleozoic era, more than 250 million years ago, trapped in impermeable salt deposits in the center of the basin. "Usually, the deeper the water, the older it is." "We were really surprised to find relatively young groundwater so deep in the subsurface," said Jihyun Kim, the paper's first author and a UArizona doctoral student in the Department of Hydrology and Atmospheric Sciences when the research was conducted. The findings are published in the journal Geophysical Research Letters. They discovered that rapid erosion of the Colorado Plateau – which led to the formation of the Colorado River and Grand Canyon – allowed newly recharged groundwater to circulate deep underground and flush away some of the much older and saltier, or saline, groundwater that settled there long ago. A University of Arizona-led team sampled the basin's groundwater from the Earth's surface down to the bottom of the basin, nearly 2 miles deep. The Paradox Basin, a deep depression filled in with sediments over millions of years, is found mostly in southeastern Utah and southwestern Colorado within the Colorado Plateau. The methods used to reveal the basin's history could also help determine the age of other bodies of groundwater in the future, as humans continue to drill deeper wells for drinking water. The groundwater there was much younger than it should have been at that depth. Roughly 6 million years after the Grand Canyon's formation, researchers studying the groundwater of the nearby Paradox Basin made a surprising discovery. The stripped gas is collected in the aluminum canister in the foreground that is sent off for analysis of individual krypton atoms using a laser system called Atom Trap Trace Analysis. Jihyun Kim and Rebecca Tyne collect dissolved krypton gas for dating groundwater.
0 Comments
Leave a Reply. |