Magnetic Telechemistry of Oceanic Crust?

Abstract

IT is now established that basalts from Iceland^1–3, the Galapagos Islands⁴, and other volcanic island and seamount^5,6 chains in general, are richer in iron and titanium than normal abyssal tholeiites produced by seafloor spreading on the Mid-Oceanic Ridge. According to present thought, these chains are the volcanic derivatives of mantle plumes over which the lithospheric plates make their way⁷. Schilling² recently showed progressive decreases in minor and trace element concentrations along the Reykjanes Ridge south west away from Iceland; he interprets this as the result of mixing of a plume and a normal, depleted asthenosphere below the spreading axis, as the Icelandic asthenosphere travels southwards in a pipe or conduit below the spreading axis⁸. The model has been challenged⁹, but the geochemical variations seem to be characteristic of plumes the world over. From an economic point of view, mid-oceanic hydro-thermal muds and brines formed near plume centres would seem best suited as mineral reserves because of the inherently higher concentration of various metals in the upper crust. Is there any way to make a rapid assay of the ocean crust to identify such regions without tedious dredging and chemical analyses?