MSGID: 1:317/3 6279ea97   
   PID: hpt/lnx 1.9.0-cur 2019-01-08   
   TID: hpt/lnx 1.9.0-cur 2019-01-08   
    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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