The Deep Submerged Continental Crust: The Central Arctic and Zealandia in the Southwest Pacific

AbstractA vast area of up to five million square kilometers is located in the Pacific Ocean to the east of Australia. The Earth’s crust up to 10–23 km thick is submerged here to a depth of 1–4 km. This contrasts with the surrounding Southwest Pacific where the crust is submerged up to 5–6 km and has a thickness of 7 km, which is more typical for oceans. As is known from dredging and deep-sea drilling, Zealandia is composed of the continental crust. For a long time, it was close to the sea level and then it subsided into the depths. The same thickness, water depths, and subsidence history are found for some domains in the Central Arctic, Lomonosov Ridge, Podvodnikov Basin, and Mendeleev Ridge. The continental nature of the crust has been proven here by drilling and is suggested by the results of study of the sea floor bedrock. Deep basins of the Central Arctic and Zealandia were formed without intense crustal stretching. Its origin can be explained by the increase in density of gabbroids in the lower crust due to prograde metamorphism.