The Kula Plate is an oceanic tectonic plate under the northern Pacific Ocean south of the Near Islands segment of the Aleutian Islands. It is subducting under the North American Plate at the Aleutian Trench and is surrounded by the Pacific Plate. There is a portion of the Kula Plate at the surface in the southern Bering Sea.
The Kula Plate began subducting under the Pacific Northwest region of North America during the Late Cretaceous period much like the Pacific Plate does, supporting a large volcanic arc system from northern Washington to southwestern Yukon called the Coast Range Arc.
There was a triple junction of three ridges between the Kula Plate to the north, the Pacific Plate to the west and the Farallon Plate to the east. The Kula Plate was subducted under the North American Plate at a relatively steep angle, so that the Canadian Rockies are primarily composed of thrusted sedimentary sheets with relatively little contribution of continental uplift, while the American Rockies are characterized by significant continental uplift in response to the shallow subduction of the Farallon Plate.
About 55 million years ago, the Kula Plate began an even more northerly motion. Riding on the Kula Plate was the Pacific Rim Terrane consisting of volcanic and sedimentary rocks. It was scraped off and plastered against the continental margin, forming what is today Vancouver Island.
By 40 million years ago, the compressional force of the Kula Plate ceased. The existence of the Kula Plate was inferred from the westward bend in the alternating pattern of magnetic anomalies in the Pacific Plate.
- Reconstruction of the Kula Plate
- Kula Plate in the area of the present Northwestern United States
- Kula plate when it separates from the Farallon plate