THOUGHTS ON THE EVOLUTION OF MODERN OCEANS

Explanation of the evolution of the Earth's oceans, particularly the p rocesses involved in the generation of the oceans, are important for u nderstanding the general appearance of our planet, and for the solutio n of specific problems. A comparative study of the world's oceans show s there is a single genetic series in the evolution of oceans, and tha t the oceans of the world are at different stages in their evolution. The Arctic Ocean, dated as Cenozoic, is noted for its small size and s hallow oceanic floor, extensive but passive continental margins, limit ed volcanism, significant crustal thickness, and a lack of Benioff zon es. The Mesozoic, Indian and Atlantic oceans have much greater dimensi ons and depths than the Arctic Ocean, the crust is thinner beneath the m, volcanism is much more extensive, and active margins, while in the initial phase of evolution, are limited in extent. The area of the mos t ancient (probably Paleozoic) Pacific Ocean is equal to the sum of th e rest of the three oceans; it also has the greatest oceanic depth. Be neath the Pacific, the crust is thinned and is characterized by high p ermeability, because of which magmatism is particularly widespread. Ac tive continental margins are also extensive in the Pacific. The concep t of evolutionary development of the oceans enables us to predict the comparative potential of oceans with regards to their oil and gas and ore content.