TheKula plate was an oceanictectonic plate under the northernPacific Ocean south of theNear Islands segment of theAleutian Islands. It has beensubducted under theNorth American plate at theAleutian Trench, being replaced by thePacific plate.
The nameKula is from aTlingit language word meaning "all gone".[1] As the name suggests, the Kula plate was entirely subducted around 48 Ma and today only a slab in the mantle under theBering Sea remains.[2] There is some evidence of aResurrection plate broken off from the Kula plate and also subducted.[3][4]
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The Kula plate begansubducting under thePacific Northwest region ofNorth America during theLate Cretaceous period much like thePacific plate does today, supporting a largevolcanic arc system from northernWashington to southwesternYukon called theCoast Range Arc.
There was atriple junction of three ridges between the Kula plate to the north, thePacific plate to the west and theFarallon plate to the east. The Kula plate was subducted under theNorth American plate at a relatively steep angle, so that theCanadian Rockies are primarily composed of thrustedsedimentary sheets with relatively little contribution of continentaluplift, 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 thePacific Rim Terrane consisting ofvolcanic andsedimentary rock. It was scraped off and plastered against thecontinental margin, forming what is todayVancouver 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 ofmagnetic anomalies in thePacific plate.
