Scientists at the Alberta University discovered the world’s oldest rock at 4.02 billion years old. The ancient rock’s composition is different than scientists expected, it suggests that early Earth was largely covered with an oceanic crust-like surface.
The lead author of the study, Jesse Reimink explained in a news release that the rock gives important information about the primal continents formed. And he added that as it’s so far back in time, they have to hold every single evidence they can. They have a very minimum data points with which to valuate what was happening on Earth at that time.
Scientists have now exposed rocks older than 4 billion years at 3 different places. The latest rock unit hails from Canada’s Northwest Territories. Scientists have previously unearthed likely ancient mineral grains in Western Australia, as well as a 4-billion-year-old rock in Northern Quebec.
The unique turn on that rock is the existence of well-preserved grains of the mineral zircon, leaving no doubt about the date it defined. Reimink said that zircons lock in also geochemical information that they exploited in the paper. He added that the rock records chemical information that the zircon grains don’t.
The rock sample was found by Tom Chacko, Reimink’s PhD supervisor in an area roughly 300 kilometers north of Yellowknife in Canada.
Reimink, who completed his PhD at the University of Alberta in Canada said, “”Rocks and zircon together give us much more information than either on their own. Zircon retains its chemical signature and records age information that doesn’t get reset by later geological events, while the rock itself records chemical information that the zircon grains don’t,”
The chemical mixture of the rock recalls of rocks forming today in Iceland, in an mediator zone between oceanic and continental crust.
While a few have posited Iceland as an ideal exemplary for how magma was first incorporated into Earth’s continental crust, scientists didn’t expect the findings from the latest study. Though the world’s oldest rock offers precious insights into the nature of early layer formation, it also increases more questions than answers.
“We examined the rock itself to analyze those chemical signatures to explore the way that the magma intrudes into the surrounding rock,” Reimink said, adding “While the magma cooled, it simultaneously heated up and melted the rock around it, and we have evidence for that.”
“There are constant feedback loops between chemistry and geology,” he said. “Though there are still a lot of unknowns, this is just one example that everything on earth is intertwined.”
The research has appeared in the Nature Geo-science journal.