Economically valuable materials such as diamonds, tin, and platinum are associated with which ocean floor resource?

Economically valuable materials such as diamonds, tin, and platinum are associated with sand and gravel.
There is no way that oil and natural gas, evaporative salts, and manganese nodules affect the creation of diamonds, platinum and tin, whereas sand and gravel do. The formation of sand and gravel is quite important for the "birth" of these materials, given that they need suitable conditions to form.