The plates that are composed mostly of oceanic crust are called oceanic plates.

Here's a breakdown:

* Oceanic Crust: Thin, dense, and composed mainly of basalt and gabbro. It's found on the ocean floor.

* Continental Crust: Thicker, less dense, and composed mainly of granite and other granitic rocks. It makes up the continents.

While some plates contain both oceanic and continental crust, the following are considered primarily oceanic plates:

* Pacific Plate (largest)

* Nazca Plate

* Cocos Plate

* Philippine Sea Plate

* Antarctica Plate (large, but includes a continental portion)

Let me know if you have any other questions!