Failed eruptions are at the origin of copper deposits
Scientists reveal a surprising mechanism in the formation of copper
deposits, an essential metal for the energy transition.
Date:
May 9, 2022
Source:
Universite' de Gene`ve
Summary:
Copper is one of the most widely used metals on the planet today
due to its electrical and thermal conduction properties. The
greatest natural resources of this metal are the so-called
'porphyry' deposits that come from magmas deep in the Earth. In
recent research, scientists demonstrate that these deposits are
largely produced by mechanisms similar to those causing large
volcanic eruptions. At a time when current copper resources are
dwindling and this metal plays a key role in the energy transition,
this discovery opens up new avenues for the development of tools
to find new deposits.
FULL STORY ========================================================================== Copper is one of the most widely used metals on the planet today due to
its electrical and thermal conduction properties. The greatest natural resources of this metal are the so-called "porphyry" deposits that come
from magmas deep in the Earth. In a recent research, scientists from
the University of Geneva (UNIGE) demonstrate that these deposits are
largely produced by mechanisms similar to those causing large volcanic eruptions. At a time when current copper resources are dwindling and this
metal plays a key role in the energy transition, this discovery opens
up new avenues for the development of tools to find new deposits. These
results can be read in the journal Nature - - Communications Earth & Environment.
========================================================================== Copper is one of the most exploited natural resources on the planet. An excellent conductor and highly resistant to corrosion, it is used to
produce all types of wires and electrical connectors. It is also used
to make many alloys, such as bronze and brass. Considered an essential
material for the energy transition -- it is massively used to equip
electric cars -- its demand will exceed the resources currently available within a few decades. Discovering new deposits and acquiring new knowledge about their formation is therefore a crucial challenge.
Research led by Massimo Chiaradia, senior lecturer at the Department of
Earth and Environmental Sciences at the UNIGE Faculty of Science, has made
an important discovery in this field. It highlights the fact that the "porphyry" deposits -- named after a magmatic rock that contains copper
-- are the result of mechanisms very similar to those that cause large
volcanic eruptions. "We have discovered that large reserves of copper
are born of failed eruptions," explains the researcher.
From the magma Copper comes from hot fluids, mostly composed of water,
released by cooling magmas. These magmas, which are also the basis of eruptions, come from the intermediate layer between the core and the
crust of the Earth, known as the "mantle," and then rise to the surface
of the Earth where they form a "magma chamber." This chamber is generally located between 5km and 15km depth. "If the volume and speed of magma
injection into this reservoir is very large, a large quantity of fluids
can be emitted catastrophically into the atmosphere with the magma during
a volcanic eruption," explains Massimo Chiaradia, first author of the
research. But these fluids can also develop in a quieter way under the
earth's surface and give rise to a porphyry copper deposit at a depth
varying between 1km and 6km.
However, this phenomenon is much less frequent, which partly explains
the rarity of copper deposits. "It takes tens to hundreds of thousands
of years for a copper deposit to form, whereas volcanic eruptions are
more frequent. A failed eruption depends on the combination of several parameters: the speed of magma injection, the speed of its cooling and
the rigidity of the earth's crust that surrounds the magma chamber. The
latter must be flexible to absorb the pressure exerted by the new magma arrivals, so that the eruption does not take place," explains Luca
Caricchi, second author and associate professor at the Department of
Earth and Environmental Sciences.
Useful for future deposit exploration "The discovery of similarities
between large eruptions and deposits will make it possible to use a
large amount of knowledge acquired by vulcanologists to advance our understanding of the formation of porphyry deposits," says Massimo
Chiaradia. To reach their results, the UNIGE scientists relied on data
and figures provided by the mining companies and on those collected in
the field and in the laboratory by numerous researchers -- combined with petrological and geochemical models.
These discoveries open new avenues for the development of geological, mineralogical and geochemical tools for future successful exploration
of the largest porphyry copper deposits on Earth. "The next step will
be to work on a model that will help us to quantify the total copper
content and therefore the quality of a potentially exploitable deposit
as accurately as possible," concludes Massimo Chiaradia.
========================================================================== Story Source: Materials provided by Universite'_de_Gene`ve. Note:
Content may be edited for style and length.
========================================================================== Journal Reference:
1. Massimo Chiaradia, Luca Caricchi. Supergiant porphyry copper
deposits are
failed large eruptions. Communications Earth & Environment, 2022;
3 (1) DOI: 10.1038/s43247-022-00440-7 ==========================================================================
Link to news story:
https://www.sciencedaily.com/releases/2022/05/220509112044.htm
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