British geologists have found out under what conditions metal ore is formed. The results of the study are published in the journal Nature Communications.
Scientists have identified the natural mechanism and conditions by which metals important for technology pass from the Earth’s mantle to the crust. In the future, this will lead to less expensive and more environmentally friendly methods of finding and extracting valuable metals. First of all, we are talking about copper, cobalt, tellurium and platinum. They are in high demand due to their use in electrical wiring and in battery devices, solar panels and fuel cells.
Metals are mostly stored in the Earth’s mantle – a thick layer of rock that lies between the planet’s core and its crust – more than 25 km deep, making them inaccessible to mining. However, in some parts of the world, natural processes “deliver” these metals to the surface through a stream of liquid rock. We are talking about magma that originates in the mantle and rises up into the earth’s crust.
However, when this happens, the metals often become trapped and cannot reach the surface if the temperature is too high or too low. However, this time they found that under ideal conditions, namely a temperature of about 1000 ° C, copper, gold and tellurium can “get out of the trap” and rise to the surface, forming ore deposits. Already there they can be mined. Up to this point, the path of metals to the place of their final deposition remained uncertain.
The results of the study will help analyze the surface and land and find places where it is more convenient to mine metals. This will allow for more targeted exploration of minerals, thereby reducing the impact on the environment.
Magmatic arcs are terrestrial environments where lithospheric cycling and recycling of metals and volatiles is enhanced. However, the first-order mechanism permitting the episodic fluxing of these elements from the mantle through to the outer Earth’s spheres has been elusive. To address this knowledge gap, we focus on the textural and minero-chemical characteristics of metal-rich magmatic sulfides hosted in amphibole-olivine-pyroxene cumulates in the lowermost crust. We show that in cumulates that were subject to increasing temperature due to prolonged mafic magmatism, which only occurs episodically during the complex evolution of any magmatic arc, Cu-Au-rich sulfide can exist as liquid while Ni-Fe rich sulfide occurs as a solid phase. This scenario occurs within a ‘Goldilocks’ temperature zone at ~1100–1200 °C, typical of the base of the crust in arcs, which permits episodic fractionation and mobilisation of Cu-Au-rich sulfide liquid into permeable melt networks that may ascend through the lithosphere providing metals for porphyry and epithermal ore deposits.
‘Mobilisation of deep crustal sulfide melts as a first order control on upper lithospheric metallogeny’ is published in Nature Communications.
