Tibetan Plateau older than thought

The Tibetan Plateau may be as much as twice as old as previously thought, geologists studying mountain ranges along the eastern edge of the plateau said. It has long been assumed the plateau was created when the Indian tectonic plate began its collision with Asia between 55 and 50 million years ago, but "significant topographic relief (height) existed adjacent to the Sichuan Basin prior to the Indo-Asian collision," the researchers reported in Nature Geoscience. "Most researchers have thought that high topography in eastern Tibet developed during the past 10 to 15 million years, as deep crust beneath the central Tibetan Plateau flowed to the plateau margin, thickening the Earth's crust in this area and causing surface uplift," Penn State professor of geoscience Eric Kirby said. "Our study suggests that high topography began to develop as early as 30 million years ago, and perhaps was present even earlier." The researchers say their studies revealed two episodes of rapid erosion of the mountain surrounding the plateau, one beginning 30 to 25 million years ago and one beginning 15 to 10 million years ago that is still ongoing. "These results challenge the idea that the topographic relief along the margin of the plateau developed entirely in the Late Miocene, 5 to 10 million years ago," Kirby said. "The period of rapid erosion between 25 to 30 million years ago could only be sustained if the mountains were not only present, but actively growing, at this time." "We are still a long way from completely understanding when and how high topography in Asia developed in response to [the] India-Asia collision," he said. "However, these results lend support to the idea that much of what we see today in the mountains of China may have developed earlier than we previously thought."