Mongol-Okhotsk Ocean

The Mongol-Okhotsk Ocean, also called the Khangai-Khantey Ocean, was a large, triangle-shaped ancient ocean. It existed from the Paleozoic to the Mesozoic time periods. Its rocks can still be found today in a special area called the Mongol-Okhotsk suture zone. This area stretches from Mongolia to the Sea of Okhotsk.

This ocean began to form during the early to middle Paleozoic era. It formed in a region called the Central Asian Orogenic Belt. Over millions of years, the ocean started to close up. This began in the Late Triassic period. The closing bent the western Mongolian landmasses and made a curved shape called the Tuva-Mongol Orocline.

Finally, the ocean closed quickly in a scissor-like motion. This led to a major event. The Erguna Block crashed into the Siberian Craton during the Late Jurassic and Early Cretaceous periods. This changed the shape of the Earth’s surface forever.

Sequence of events

When the supercontinent Pangea formed, the huge Panthalassa ocean covered most of Earth. Smaller oceans were there too, like the Tethys and the Mongol-Okhotsk Ocean.

Later, big land masses came together. This left a line of rocks called the Mongol-Okhotsk suture zone. Scientists study these rocks to learn about Earth's past. Some rocks are very old — about 325 million years!