Why does the crust of a sea mountain have such an amazing concentration of minerals including rare earth minerals?
Is Tropic Seamount unique or are lots of sea mountains rich in minerals?
Why is the ocean floor around Tropic Seamount so flat?
Why does it have such a strange shape and sharp ridges?
A tropical sea mountain of minerals
British scientists exploring an underwater mountain in the Atlantic Ocean have discovered a treasure trove of rare minerals. Their investigation of a seamount more than 500km (300 miles) from the Canary Islands has revealed a crust of “astonishingly rich” rock. Samples brought back to the surface contain the scarce substance tellurium in concentrations 50,000 times higher than in deposits on land …
the crust is dark and fine-grained and stretches in a layer roughly 4cm thick over the entire surface of the mountain … he had been expecting to find abundant minerals on the seamount but not in such concentrations. “These crusts are astonishingly rich and that’s what makes these rocks so incredibly special and valuable from a resource perspective.” He has calculated that the 2,670 tonnes of tellurium on this single seamount represents one-twelfth of the world’s total supply.
Renewables’ deep-sea mining conundrum
Sea volcanoes or lava mountains?
If most seamounts are formed by volcanic activity why are volcanoes found on land not so rich in rare earth minerals and especially tellurium?
Most material dredged from seamounts is microcrystalline, or glassy, oceanic basalt that probably formed as submarine lava flows. The summits and flanks of seamounts are generally covered with a thin layer of marine sediment. Seamounts are exceedingly abundant and occur in all major ocean basins. By the late 1970s more than 10,000 seamounts had been reported from the Pacific Ocean basin alone. Virtually every oceanographic expedition discovers new seamounts, and it is estimated that approximately 20,000 exist in the oceans of the world.
A linear cluster of seamounts may result when several are fed by lava extruded from a single linear rift. Most Pacific seamounts occur in linear clusters or elongate groups of 10 to 100. The individual seamounts in a chain may share a common ridge connecting their bases, as in the Mid-Pacific Mountains. Seamount chains in the Pacific basin tend to be aligned northwesterly, and several chains are intimately associated with fracture zones; the Eltanin Fracture Zone in the southwestern Pacific is an example. At least one seamount chain, the New England Seamounts, lies in the northwestern Atlantic. No seamount chains have been reported from the Indian Ocean, possibly because that basin has been less extensively surveyed.
Seamount | Encyclopædia Britannica
Hotspot for minerals and seamounts
With all that plate tectonics, subduction and regurgitation the Canary Island Seamount Province and the Tropic Seamount have even been suggested as the oldest on planet, or ocean crust, Earth.
Is the rich layer of minerals just the surface layer or does it go deeper?
Where the rare minerals formed during the formation of the underwater mountain or was its surface transformed afterwards and the elements transmuted into minerals?
The Canary Island Seamount Province forms a scattered hotspot track on the Atlantic ocean floor ~1300 km long and ~350 km wide, perpendicular to lithospheric fractures, and parallel to the NW African continental margin. New 40Ar/39Ar datings show that seamount ages vary from 133 Ma to 0.2 Ma in the central archipelago, and from 142 Ma to 91 Ma in the southwest. Combining 40Ar/39Ar ages with plate tectonic reconstructions, I find that the temporal and spatial distribution of seamounts is irreconcilable with a deep fixed mantle plume origin, or derivation from passive mantle upwelling beneath a mid-ocean ridge. I conclude that shallow mantle upwelling beneath the Atlantic Ocean basin off the NW African continental lithosphere flanks produced recurrent melting anomalies and seamounts from the Late Jurassic to Recent, nominating the Canary Island Seamount Province as oldest hotspot track in the Atlantic Ocean, and most long-lived preserved on earth.
The origin of the Canary Island Seamount Province – New ages of old seamounts