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What happened di Southeast Asia 50 million years ago? Science answers!
NATURE Beyond

What happened di Southeast Asia 50 million years ago? Science answers!

Asia is not just the world's largest continent, but also its newest and most structurally complex. Despite the fact that Asia's evolution started almost four billion years ago, more than half of the continent is still seismically active. 

The island arc systems that encircle it to the east and southeast are currently producing new continental material. New land is constantly forming in such regions, and occasional collisions of the island arcs with the mainland add to the mass of the continent.

Asia also has the world's largest mountain ranges: the Tibetan Plateau and Himalayan surrounding mountains, Karakoram Range, Hindu Kush, Pamirs, Kunlun Mountains, and Tien Shan. 

Asia has several of the morphological extremes of Earth's land surface, such as the highest and lowest points, longest coastline, and biggest area of the continental shelf, due to its huge size and relative young. The huge mountain ranges, various coastlines, and massive continental plains and basins of Asia have had a tremendous impact on human history.

The fact that Asia produces vast amounts of fossil fuels—petroleum, natural gas, and coal—in addition to contributing significantly to the global production of many minerals (e.g., about three-fifths of the world's tin) emphasizes the significance of its geology for the welfare of the global population.

When the landmass that is now the Indian subcontinent collided with Asia 50 million years ago, it affected the continents' layout as well as the world climate.

A group of Princeton University scientists has discovered yet another effect: the amount of oxygen in the world's oceans has grown, altering life circumstances. The findings were reported in the Science magazine. The research was supported by the National Science Foundation's Division of Ocean Sciences.

Geoscientists utilized minute fossil shells to reconstruct a 40-million-year record of ocean nitrogen, from 70 million years ago, right before dinosaur extinction, to 30 million years ago. The researchers took soil containing fossils from the ocean's depths in the Atlantic and Pacific Oceans and studied the nitrogen trapped in the minuscule shells. The amount of oxygen dissolved in the water affects nitrogen levels.

Because oxygen is more soluble in cooler water, the researchers predicted that ocean oxygen would rise as the Earth's climate cooled. Data on nitrogen in those prehistoric times, on the other hand, revealed that oxygen levels surged several million years before widespread cooling.

The most likely offender? Tectonic plates. The collision of India and Asia closed off the Tethys, an ancient sea where low-oxygen waters evolved, altering the ocean's oxygen and nitrogen balance.

Source: Britannica.com, NSF.gov/discoveries

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