tag:theconversation.com,2011:/nz/topics/subduction-48862/articlesSubduction – The Conversation2022-11-28T18:31:32Ztag:theconversation.com,2011:article/1916732022-11-28T18:31:32Z2022-11-28T18:31:32ZWhere did the Earth’s oxygen come from? New study hints at an unexpected source<p>The amount of oxygen in the Earth’s atmosphere makes it a habitable planet.</p>
<p>Twenty-one per cent of the atmosphere consists of this life-giving element. But in the deep past — as far back as the Neoarchean era 2.8 to 2.5 billion years ago — <a href="https://doi.org/10.1126/sciadv.aax1420">this oxygen was almost absent</a>. </p>
<p>So, how did Earth’s atmosphere become oxygenated? </p>
<p><a href="https://www.nature.com/articles/s41561-022-01071-5">Our research</a>, published in <em>Nature Geoscience</em>, adds a tantalizing new possibility: that at least some of the Earth’s early oxygen came from a tectonic source via the movement and destruction of the Earth’s crust.</p>
<h2>The Archean Earth</h2>
<p>The Archean eon represents one third of our planet’s history, from 2.5 billion years ago to four billion years ago. </p>
<p>This alien Earth was a water-world, covered in <a href="https://doi.org/10.1038/ngeo2878">green oceans</a>, shrouded in a <a href="https://doi.org/10.1089/ast.2007.0197">methane haze</a> and completely lacking multi-cellular life. Another alien aspect of this world was the nature of its tectonic activity. </p>
<p>On modern Earth, the dominant tectonic activity is called plate tectonics, where oceanic crust — the outermost layer of the Earth under the oceans — sinks into the Earth’s mantle (the area between the Earth’s crust and its core) at points of convergence called subduction zones. However, there is considerable debate over whether plate tectonics operated back in the Archean era. </p>
<p>One feature of modern subduction zones is their association with <a href="https://doi.org/10.1002/9781119473206.ch3">oxidized magmas</a>. These magmas are formed when oxidized sediments and bottom waters — cold, dense water near the ocean floor — are <a href="https://doi.org/10.1073/pnas.1821847116">introduced into the Earth’s mantle</a>. This produces magmas with high oxygen and water contents. </p>
<p>Our research aimed to test whether the absence of oxidized materials in Archean bottom waters and sediments could prevent the formation of oxidized magmas. The identification of such magmas in Neoarchean magmatic rocks could provide evidence that subduction and plate tectonics occurred 2.7 billion years ago.</p>
<h2>The experiment</h2>
<p>We collected samples of 2750- to 2670-million-year-old granitoid rocks from across the Abitibi-Wawa subprovince of the Superior Province — the largest preserved Archean continent stretching over 2000 km from Winnipeg, Manitoba to far-eastern Quebec. This allowed us to investigate the level of oxidation of magmas generated across the Neoarchean era. </p>
<figure class="align-left zoomable">
<a href="https://images.theconversation.com/files/489928/original/file-20221017-23-zslasf.jpeg?ixlib=rb-1.1.0&rect=0%2C619%2C3565%2C3116&q=45&auto=format&w=1000&fit=clip"><img alt="Dr. Xuyang Meng collecting a rock sample in Rouyn-Noranda, Que." src="https://images.theconversation.com/files/489928/original/file-20221017-23-zslasf.jpeg?ixlib=rb-1.1.0&rect=0%2C619%2C3565%2C3116&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/489928/original/file-20221017-23-zslasf.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/489928/original/file-20221017-23-zslasf.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/489928/original/file-20221017-23-zslasf.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/489928/original/file-20221017-23-zslasf.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/489928/original/file-20221017-23-zslasf.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/489928/original/file-20221017-23-zslasf.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">The 2750- to 2670-million-year-old granitoid rocks collected from the largest preserved Archean continent may help reveal the origin story of the Earth’s oxygen.</span>
<span class="attribution"><span class="source">(Dylan McKevitt)</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>Measuring the oxidation-state of these magmatic rocks — formed through the cooling and crystalization of magma or lava — is challenging. <a href="https://www.nationalgeographic.com/science/article/news-earth-rocks-sediment-first-life-zircon">Post-crystallization events may have modified these rocks through later deformation, burial or heating.</a></p>
<p>So, we decided to look at the <a href="https://www.mindat.org/min-29229.html">mineral <em>apatite</em></a> which is present in the <a href="https://www.mindat.org/min-4421.html">zircon crystals</a> in these rocks. Zircon crystals can withstand the intense temperatures and pressures of the post-crystallization events. They retain clues about the environments in which they were originally formed and provide precise ages for the rocks themselves. </p>
<p>Small apatite crystals that are less than 30 microns wide — the size of a human skin cell — are trapped in the zircon crystals. They contain sulfur. By measuring the amount of sulfur in apatite, we can establish whether the apatite grew from an oxidized magma. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/489940/original/file-20221017-11-1mj81z.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Map of Canada showing the location of the Superior Province in the east of the country." src="https://images.theconversation.com/files/489940/original/file-20221017-11-1mj81z.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/489940/original/file-20221017-11-1mj81z.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=511&fit=crop&dpr=1 600w, https://images.theconversation.com/files/489940/original/file-20221017-11-1mj81z.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=511&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/489940/original/file-20221017-11-1mj81z.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=511&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/489940/original/file-20221017-11-1mj81z.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=643&fit=crop&dpr=1 754w, https://images.theconversation.com/files/489940/original/file-20221017-11-1mj81z.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=643&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/489940/original/file-20221017-11-1mj81z.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=643&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Map of the Superior Province that stretches from central Manitoba to eastern Quebec in Canada.</span>
<span class="attribution"><span class="source">(Xuyang Meng)</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>We were able to successfully measure the <a href="https://doi.org/10.1007/978-3-642-11274-4_4021">oxygen fugacity</a> of the original Archean magma — which is essentially the amount of free oxygen in it — using a specialized technique called X-ray Absorption Near Edge Structure Spectroscopy (<a href="http://www.cei.washington.edu/education/science-of-solar/xray-absorption-near-edge-spectroscopy-xanes/">S-XANES</a>) at the Advanced Photon Source synchrotron at <a href="https://www.anl.gov/">Argonne National Laboratory in Illinois</a>. </p>
<h2>Creating oxygen from water?</h2>
<p>We found that the magma sulfur content, which was initially around zero, increased to 2000 parts per million around 2705 million years. This indicated the magmas had become more sulfur-rich. Additionally, the <a href="https://doi.org/10.1093/petrology/egab079">predominance of S6+ — a type of sulfer ion — in the apatite</a> suggested that the sulfur was from an oxidized source, matching <a href="https://doi.org/10.1016/j.precamres.2021.106104">the data from the host zircon crystals.</a></p>
<p>These new findings indicate that oxidized magmas did form in the Neoarchean era 2.7 billion years ago. The data show that the lack of dissolved oxygen in the Archean ocean reservoirs did not prevent the formation of sulfur-rich, oxidized magmas in the subduction zones. The oxygen in these magmas must have come from another source, and was ultimately released into the atmosphere during volcanic eruptions.</p>
<p>We found that the occurrence of these oxidized magmas correlates with major gold mineralization events in the Superior Province and Yilgarn Craton (Western Australia), demonstrating a connection between these oxygen-rich sources and global world-class ore deposit formation.</p>
<figure class="align-center ">
<img alt="Oxygen" src="https://images.theconversation.com/files/497078/original/file-20221123-16-sl0vkx.jpg?ixlib=rb-1.1.0&rect=40%2C172%2C5422%2C3448&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/497078/original/file-20221123-16-sl0vkx.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/497078/original/file-20221123-16-sl0vkx.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/497078/original/file-20221123-16-sl0vkx.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/497078/original/file-20221123-16-sl0vkx.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/497078/original/file-20221123-16-sl0vkx.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/497078/original/file-20221123-16-sl0vkx.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">The driving of ocean water deep into the Earth, caused by the sliding of oceanic plates under the Earth’s continental plates, may generate free oxygen as well as the mechanism to release it — volcanoes.</span>
<span class="attribution"><span class="source">(Shutterstock)</span></span>
</figcaption>
</figure>
<p>The implications of these oxidized magmas go beyond the understanding of early Earth geodynamics. Previously, it was thought unlikely that Archean magmas could be oxidized, when the <a href="https://doi.org/10.1126/science.1078265">ocean water</a> and <a href="https://doi.org/10.1038/nature25009">ocean floor rocks or sediments</a> were not. </p>
<p>While the exact mechanism is unclear, the occurrence of these magmas suggests that the process of subduction, where ocean water is taken hundreds of kilometres into our planet, generates free oxygen. This then oxidizes the overlying mantle. </p>
<p>Our study shows that Archean subduction could have been a vital, unforeseen factor in the oxygenation of the Earth, the early <a href="https://doi.org/10.1038/ngeo2939">whiffs of oxygen 2.7 billion years ago</a> and also the <a href="https://doi.org/10.1016/B978-0-08-095975-7.01307-3">Great Oxidation Event, which marked an increase in atmospheric oxygen by two per cent 2.45 to 2.32 billion years ago</a>.</p>
<p>As far as we know, the Earth is the only place in the solar system — past or present — with plate tectonics and active subduction. This suggests that this study could partly explain the lack of oxygen and, ultimately, life on the other rocky planets in the future as well.</p><img src="https://counter.theconversation.com/content/191673/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>David Mole received funding from Canada First Research Excellence Fund (CFREF) and additional federal, provincial, and industry partners as part of the Metal Earth project; a Canadian geoscience research program led by Laurentian University. The $104-million dollar project started in 2016, and is transforming our understanding of the genesis of base and precious metal deposits during Earth’s evolution. This initiative has created a strategic consortium of allied Canadian and international researchers, government, and industry. The Metal Earth grant project # is CFREF-2015-00005. David currently works for Geoscience Australia, who were not involved in this work.</span></em></p><p class="fine-print"><em><span>Adam C. Simon received funding from the U.S. National Science Foundation EAR grants #2214119 and 1924142.</span></em></p><p class="fine-print"><em><span>Xuyang Meng receives funding from Canada First Research Excellence Fund (CFREF-2015-00005), Natural Science Foundation of China, U.S. National Science Foundation EAR, and a doctoral scholarship from China Scholarship Council.</span></em></p>Could tectonic processes in the early Earth have contributed to the rise of oxygen?David Mole, Postdoctoral fellow, Earth Sciences, Laurentian UniversityAdam Charles Simon, Arthur F. Thurnau Professor, Earth & Environmental Sciences, University of MichiganXuyang Meng, Postdoctoral Fellow, Earth and Environmental Sciences, University of MichiganLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1612142021-06-01T11:28:50Z2021-06-01T11:28:50ZHow we discovered a giant new crustacean scavenging on the deepest depths of the ocean floor<figure><img src="https://images.theconversation.com/files/401617/original/file-20210519-13-168up36.JPG?ixlib=rb-1.1.0&rect=121%2C675%2C4039%2C2032&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">_Eurythenes atacamensis_, a giant scavenging amphipod from hadal depths of the Peru-Chile Trench.</span> <span class="attribution"><a class="source" href="https://doi.org/10.1007/s12526-021-01182-z">Alan Jamieson</a>, <span class="license">Author provided</span></span></figcaption></figure><p>Discovering a new species and placing it on the tree of life is a big responsibility. I have been fortunate to name four species from some of the <a href="https://doi.org/10.11646/zootaxa.4748.1.9">deepest</a>, most remote and <a href="https://doi.org/10.1080/14772000.2020.1729891">least sampled</a> parts of the ocean. Each new species helps us uncover how life thrives in the <a href="https://books.google.co.uk/books?hl=en&lr=&id=hqsPBgAAQBAJ&oi=fnd&pg=PR1&dq=jamieson+hadal+zone&ots=mwSGRXURPG&sig=UknVAyND0muPevPRqfvTtWB3BQs#v=onepage&q=jamieson%20hadal%20zone&f=false">hadal zone</a> (anywhere deeper than 6,000 metres or 3.7 miles). Now, let me introduce you to <a href="https://doi.org/10.1007/s12526-021-01182-z"><em>Eurythenes atacamensis</em></a>.</p>
<p><em>Eurythenes atacamensis</em> is an amphipod, a type of crustacean closely related to a shrimp, endemic to the <a href="https://www.britannica.com/place/Peru-Chile-Trench">Peru-Chile Trench</a> (also known as the Atacama Trench). Measuring more than 8cm in length, it is nearly twice the size of its nearest relative, making it a giant. Spanning an extensive vertical range, juveniles and adults can be found in the trench between 4,974 to 8,081 metres. This includes the deepest point, known as Richard’s Deep. </p>
<p>It is one of the most abundant members of the trench community, joining a <a href="https://theconversation.com/snailfish-how-we-found-a-new-species-in-one-of-the-oceans-deepest-places-103003">trio of snailfish</a> and long-legged, spider-like <a href="https://www.youtube.com/watch?v=txSOP_9yLCI">isopods</a>. As a <a href="https://doi.org/10.4319/lo.2007.52.4.1685">scavenger</a>, this amphipod plays a critical role within the food web by intercepting and redistributing food sinking down from above. They quickly detect and consume new carrion, like the mackerel bait we used to coax individuals into the trap. Unfortunately, they can accidentally ingest <a href="https://doi.org/10.1098/rsos.180667">microplastics</a> too.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/bFqluXB9HcE?wmode=transparent&start=10" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Timelapse of <em>Eurythenes atacamensis</em> feasting on the baited scientific lander at 6,980 metres deep in the Atacama Trench.</span></figcaption>
</figure>
<p>Their home is one of <a href="https://doi.org/10.1016/j.pocean.2018.01.007">35 trenches</a> that reach hadal depths. These trenches are formed by a geologic process called subduction (where one tectonic plate is forced under another causing the ocean floor to quickly plunge). The volume of the Atacama Trench is almost the same as the neighbouring Andes mountain range, also created by the tectonic subduction zone. </p>
<figure class="align-right ">
<img alt="Colour map of Atacama Trench." src="https://images.theconversation.com/files/402227/original/file-20210523-17-1agzf2x.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/402227/original/file-20210523-17-1agzf2x.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=1184&fit=crop&dpr=1 600w, https://images.theconversation.com/files/402227/original/file-20210523-17-1agzf2x.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=1184&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/402227/original/file-20210523-17-1agzf2x.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=1184&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/402227/original/file-20210523-17-1agzf2x.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1488&fit=crop&dpr=1 754w, https://images.theconversation.com/files/402227/original/file-20210523-17-1agzf2x.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1488&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/402227/original/file-20210523-17-1agzf2x.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1488&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Atacama Trench in dark blue running along the spine of Peru to Chile.</span>
<span class="attribution"><span class="source">NOAA/Wikipedia</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>Compared to the conditions at the surface, the <a href="https://doi.org/10.1016/j.tree.2009.09.009">hadal (or deep-sea) environment</a> seems extreme. It is pitch black with water temperatures varying between 1°C and 4°C at the deepest points. The hydrostatic pressure at hadal depths ranges from 600 to 1,100 atmospheres – equivalent to placing one-tonne on the end of your finger.</p>
<p>But this environment is entirely normal to the organisms that live there. Hadal inhabitants have a suite of biochemical, morphological and behavioural <a href="http://digital.ecomagazine.com/publication/?i=562381&article_id=3286789&view=articleBrowser&ver=html5">adaptions</a> that allow them to thrive in the trenches. Studying these ecosystems is not an easy task – which is why the hadal zone has been understudied compared to shallower parts of the ocean. </p>
<p>In 2018 two international research expeditions focused on the southern portion of the Atacama Trench. Scientists first set off on the Chilean vessel, RV Cabo de Hornos, to study the deepest part of the trench, Richard’s Deep, as part of the <a href="https://en.imo-chile.cl/post/2018-02-10-un-viaje-a-nuestro-mar-inescrutable-la-fosa-de-atacama.html">Atacamex expedition</a>. A month later, scientists on the German vessel, RV Sonne, <a href="https://epic.awi.de/id/eprint/49388/1/BzPM_0729_2019.pdf">studied</a> the wider trench ecosystem, sampling from 2,500 metres to Richard’s Deep.</p>
<p>During the expeditions, unmanned submersibles called <a href="https://www.sdu.dk/en/forskning/hadal/research/lander+work">landers</a> were deployed. Landers were equipped with robust deep-sea imaging equipment and baited traps to bring animals up for closer inspection. Both expeditions were a success and collected hundreds of hours of footage and thousands of amphipods – including <em>Eurythenes atacamensis</em> – as well as a <a href="https://theconversation.com/snailfish-how-we-found-a-new-species-in-one-of-the-oceans-deepest-places-103003">new species of snailfish</a>, affectionately nicknamed the “Little Purple Lovely” until its official scientific name is decided. </p>
<figure class="align-center ">
<img alt="A drawing of an deep-sea creature." src="https://images.theconversation.com/files/402228/original/file-20210523-13-1hlljwb.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/402228/original/file-20210523-13-1hlljwb.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=297&fit=crop&dpr=1 600w, https://images.theconversation.com/files/402228/original/file-20210523-13-1hlljwb.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=297&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/402228/original/file-20210523-13-1hlljwb.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=297&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/402228/original/file-20210523-13-1hlljwb.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=374&fit=crop&dpr=1 754w, https://images.theconversation.com/files/402228/original/file-20210523-13-1hlljwb.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=374&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/402228/original/file-20210523-13-1hlljwb.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=374&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Scientific illustration of the <em>Eurythenes atacamensis</em> holotype, a female from 8052 metres in the Atacama Trench.</span>
<span class="attribution"><span class="source">Johanna Weston/Marine Biodiversity</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>Once the specimens were back on land, the detailed work to sort, measure, identify and describe new species commenced. <em>Eurythenes atacamensis</em> is a member of a well-studied deep-sea genus (<em>Eurythenes</em>), which is notorious for what is known as <a href="https://doi.org/10.11646/zootaxa.3971.1.1">cryptic speciation</a>. In other words, when it is hard to visually tell one species from another. The fantastic photographs of <em>Eurythenes atacamensis</em> were actually taken back in a <a href="https://doi.org/10.3354/meps10489">2009 expedition</a> to the trench. </p>
<p>At the time, it was first identified as <em>Eurythenes gryllus</em>. With the new 2018 specimens, we accounted for cryptic speciation by applying an <a href="https://doi.org/10.1186/1742-9994-7-16">integrative taxonomy approach</a> – pairing traditional morphology (the detailed study of an organism’s shape) with <a href="https://theconversation.com/dna-barcoding-a-better-way-to-discover-species-4933">DNA barcoding</a>. This latest research showed it was actually a different and undescribed species. </p>
<p>This taxonomic process helped us categorise organisms so we could more easily communicate the biological information. Together, the detailed visual assessment and genetics gave us a clear result that <em>Eurythenes atacamensis</em> was a new species. Once confident in the data, we selected several individuals to be described and illustrated. These individuals are called type specimens – the most important of which is the <a href="https://ecologyforthemasses.com/2019/09/12/preserving-biological-heritage-the-importance-of-type-specimens/">holotype</a> or the “name-bearing” specimen. We chose the name <em>atacamensis</em> in tribute to its home.</p>
<p>This discovery is another piece in the puzzle of understanding the world that we live in and the subtle interactions between organisms and their environment. It helps us understand how life thrives in the deepest parts of the ocean, under conditions that seem impossible to terrestrial mammals like us. It also gives us a glimpse into the hadal zone – not an extreme habitat bereft of life, but one filled with extraordinary biodiversity.</p><img src="https://counter.theconversation.com/content/161214/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>The RV Sonne SO261 Expedition was funded by the HADES–ERC Advanced Grant “Benthic diagenesis and microbiology of hadal trenches” (Grant Agreement Number 669947) and the German Federal Ministry of Education and Research. The Atacamex Expedition was funded by the National Agency for Research and Development of Chile (ANID; Grant AUB 150006/12806). Additional support came from the Danish National Research Foundation, HADAL, (Grant number DNRF145), ANID through the Millennium Science Initiative Program (Grant ICN 12_019-IMO), and internal funding from Newcastle University</span></em></p>Deep ocean trenches are home to extraordinary biodiversity waiting to be discovered.Johanna Weston, PhD Marine Science candidate, School of Natural and Environmental Sciences, Newcastle UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1484042020-11-02T20:01:34Z2020-11-02T20:01:34ZMagnetism of Himalayan rocks reveals the mountains’ complex tectonic history<figure><img src="https://images.theconversation.com/files/365671/original/file-20201026-17-199ct3j.jpg?ixlib=rb-1.1.0&rect=155%2C0%2C2993%2C1999&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Himalayan rocks hold magnetic clues about their origins.</span> <span class="attribution"><span class="source">Craig Robert Martin</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span></figcaption></figure><p>Breathing quickly in the thin mountain air, my colleagues and I set down our equipment. We’re at the base of a jagged outcrop that protrudes upwards out of a steep gravel slope.</p>
<p>The muffled soundscape of the spectacular Himalayan wilderness is punctuated by a military convoy roaring along the Khardung-La road below. It’s a reminder how close we are to the long-disputed borders between India, Pakistan and China which lie on the ridgelines just a few miles away.</p>
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<p>This area also contains a different type of boundary, a narrow sinuous geological structure that stretches along the length of the Himalayan mountain range. Known as a suture zone, it’s only a few kilometers wide and consists of slivers of different types of rocks all sliced together by fault zones. It marks the boundary where two tectonic plates fused together and an ancient ocean disappeared.</p>
<p>Our team of geologists traveled here to collect rocks that erupted as lava more than 60 million years ago. By decoding the magnetic records preserved inside them, we hoped to reconstruct the geography of ancient landmasses – and <a href="https://doi.org/10.1073/pnas.2009039117">revise the story of the creation of the Himalayas</a>.</p>
<h2>Sliding plates, growing mountains</h2>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/366741/original/file-20201030-23-t6znxn.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="artist's rendering of two tectonic plates colliding at a subduction zone" src="https://images.theconversation.com/files/366741/original/file-20201030-23-t6znxn.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/366741/original/file-20201030-23-t6znxn.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=489&fit=crop&dpr=1 600w, https://images.theconversation.com/files/366741/original/file-20201030-23-t6znxn.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=489&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/366741/original/file-20201030-23-t6znxn.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=489&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/366741/original/file-20201030-23-t6znxn.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=614&fit=crop&dpr=1 754w, https://images.theconversation.com/files/366741/original/file-20201030-23-t6znxn.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=614&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/366741/original/file-20201030-23-t6znxn.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=614&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">At a subduction zone, two tectonic plates collide, with one slowly sliding beneath the other.</span>
<span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/illustration/tectonic-plates-world-map-royalty-free-illustration/889618718">VectorMine/iStock via Getty Images Plus</a></span>
</figcaption>
</figure>
<p>Tectonic plates make up the surface of Earth, and they’re constantly in motion – drifting at the <a href="https://www.sciencedirect.com/topics/earth-and-planetary-sciences/tectonic-plate">imperceptibly slow pace</a> of just a few centimeters each year. Oceanic plates are colder and denser than the mantle beneath them, so they sink downward into it at subduction zones.</p>
<p>The sinking edge of the ocean plate drags the ocean floor along behind it like a conveyor belt, pulling the continents toward each other. When the entire ocean plate disappears into <a href="https://www.nationalgeographic.org/encyclopedia/mantle/">the mantle</a>, the continents on either side plow into each other with enough force to uplift great mountain belts, like the Himalayas.</p>
<p>Geologists generally thought that the Himalayas formed <a href="https://doi.org/10.1130/0016-7606(2000)112%3C324:TOTHAS%3E2.0.CO;2">55 million years ago in a single continental collision</a> – when the Neotethys Ocean plate subducted under the southern edge of Eurasia and the Indian and Eurasian tectonic plates collided. </p>
<p>But by measuring the magnetism of rocks from northwest India’s remote and mountainous Ladakh region, our team has shown that the tectonic collision that formed the world’s largest mountain range was actually a complex, multi-stage process involving at least two subduction zones.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/366500/original/file-20201029-13-1784e5k.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="diagram of interior of Earth and magnetic field stretching from pole to pole" src="https://images.theconversation.com/files/366500/original/file-20201029-13-1784e5k.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/366500/original/file-20201029-13-1784e5k.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=646&fit=crop&dpr=1 600w, https://images.theconversation.com/files/366500/original/file-20201029-13-1784e5k.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=646&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/366500/original/file-20201029-13-1784e5k.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=646&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/366500/original/file-20201029-13-1784e5k.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=811&fit=crop&dpr=1 754w, https://images.theconversation.com/files/366500/original/file-20201029-13-1784e5k.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=811&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/366500/original/file-20201029-13-1784e5k.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=811&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Earth’s magnetic field is generated by movement within the planet’s outer core. Magnetic north and south drift and sometimes flip over time.</span>
<span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/illustration/earth-magnetic-field-scientific-vector-royalty-free-illustration/932342344">VectorMine/iStock via Getty Images Plus</a></span>
</figcaption>
</figure>
<h2>Magnetic messages, preserved for all time</h2>
<p>Constant movement of our planet’s metallic outer core creates electric currents which in turn generate <a href="https://cosmosmagazine.com/geoscience/what-creates-earth-s-magnetic-field/">Earth’s magnetic field</a>. It’s oriented differently depending where in the world you are. The magnetic field always points toward the magnetic north or the south, which is why your compass works, and averaged over thousands of years it points toward the geographic pole. But it also slopes downward into the ground at an angle which varies depending on how far you are from the equator. </p>
<p>When lava erupts and cools to form rock, the magnetic minerals inside lock in the direction of the magnetic field of that location. So <a href="https://doi.org/10.1016/B0-12-369396-9/00106-4">by measuring the magnetization of volcanic rocks</a>, <a href="https://scholar.google.com/citations?hl=en&user=aD8WioMAAAAJ">scientists like me</a> can determine what latitude they came from. Essentially, this method allows us to unwind millions of years of plate tectonic motions and create maps of the world at different times throughout geologic history.</p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/365226/original/file-20201023-20-172l0hn.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Member of our research team collecting samples in Ladakh." src="https://images.theconversation.com/files/365226/original/file-20201023-20-172l0hn.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/365226/original/file-20201023-20-172l0hn.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=884&fit=crop&dpr=1 600w, https://images.theconversation.com/files/365226/original/file-20201023-20-172l0hn.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=884&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/365226/original/file-20201023-20-172l0hn.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=884&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/365226/original/file-20201023-20-172l0hn.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1111&fit=crop&dpr=1 754w, https://images.theconversation.com/files/365226/original/file-20201023-20-172l0hn.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1111&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/365226/original/file-20201023-20-172l0hn.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1111&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Geologist collects core samples using a water-cooled electric core drill.</span>
<span class="attribution"><span class="source">Craig Robert Martin</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<p>Over multiple expeditions to the Ladakh Himalayas, our team collected hundreds of 1-inch diameter rock core samples. These rocks originally formed on a volcano active between 66 and 61 million years ago, around the time that the first stages of collision began. We used a hand-held electric drill with a specially designed diamond coring bit to drill approximately 10 centimeters down into the bedrock. We then carefully marked these cylindrical cores with their original orientation before chiseling them out of the rock with nonmagnetic tools.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/366238/original/file-20201028-15-ujjeor.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="cylindrical rock core samples with markings" src="https://images.theconversation.com/files/366238/original/file-20201028-15-ujjeor.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/366238/original/file-20201028-15-ujjeor.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=431&fit=crop&dpr=1 600w, https://images.theconversation.com/files/366238/original/file-20201028-15-ujjeor.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=431&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/366238/original/file-20201028-15-ujjeor.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=431&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/366238/original/file-20201028-15-ujjeor.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=542&fit=crop&dpr=1 754w, https://images.theconversation.com/files/366238/original/file-20201028-15-ujjeor.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=542&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/366238/original/file-20201028-15-ujjeor.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=542&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">A few rock core samples, with the sample orientation line marked on their sides.</span>
<span class="attribution"><span class="source">Craig Robert Martin</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<p>The aim was to reconstruct where these rocks originally formed, before they were sandwiched between India and Eurasia and uplifted into the high Himalayas. Keeping track of the orientation of the samples as well as the rock layers they came from is essential to calculating which way the ancient magnetic field pointed relative to the surface of the ground as it was over 60 million years ago.</p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/365268/original/file-20201023-19-1igxsu8.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="View of magnetometer equipment at MIT." src="https://images.theconversation.com/files/365268/original/file-20201023-19-1igxsu8.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/365268/original/file-20201023-19-1igxsu8.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=800&fit=crop&dpr=1 600w, https://images.theconversation.com/files/365268/original/file-20201023-19-1igxsu8.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=800&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/365268/original/file-20201023-19-1igxsu8.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=800&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/365268/original/file-20201023-19-1igxsu8.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1005&fit=crop&dpr=1 754w, https://images.theconversation.com/files/365268/original/file-20201023-19-1igxsu8.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1005&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/365268/original/file-20201023-19-1igxsu8.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1005&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">The magnetometer sits inside a magnetically shielded room at the MIT Paleomagnetism Laboratory.</span>
<span class="attribution"><span class="source">Craig Robert Martin</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<p>We brought our samples back to the <a href="http://www.benweiss.mit.edu/">MIT Paleomagnetism Laboratory</a> and, inside a special room that’s shielded from the modern-day magnetic field, we heated them in increments up to 1,256 degrees Fahrenheit (680 degrees Celsius) to slowly remove the magnetization.</p>
<p>Different mineral populations acquire their magnetization at different temperatures. Incrementally heating and then measuring the samples in this way enables us to extract the original magnetic direction by removing more recent overprints that might hide it.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/366244/original/file-20201028-17-hpwmb7.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="diagrams depicting India colliding with Eurasia either in a single stage or multiple stages" src="https://images.theconversation.com/files/366244/original/file-20201028-17-hpwmb7.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/366244/original/file-20201028-17-hpwmb7.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=239&fit=crop&dpr=1 600w, https://images.theconversation.com/files/366244/original/file-20201028-17-hpwmb7.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=239&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/366244/original/file-20201028-17-hpwmb7.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=239&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/366244/original/file-20201028-17-hpwmb7.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=301&fit=crop&dpr=1 754w, https://images.theconversation.com/files/366244/original/file-20201028-17-hpwmb7.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=301&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/366244/original/file-20201028-17-hpwmb7.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=301&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Black lines mark boundaries between tectonic plates. Black lines with triangular tick marks show subduction zones, with the direction of subduction. The Trans-Tethyan Subduction Zone is the additional subduction zone not accounted for in the single-stage collision model. The Trans-Tethyan Subduction Zone is where the volcanic island chain formed before the Indian continent collided into it and pushed it into Eurasia, forming the Himalaya.</span>
<span class="attribution"><a class="source" href="https://doi.org/10.1073/pnas.2009039117">Martin et al 'Paleocene latitude of the Kohistan-Ladakh arc indicates multi-stage India-Eurasia collision,' PNAS 2020</a>, <a class="license" href="http://creativecommons.org/licenses/by-nc-sa/4.0/">CC BY-NC-SA</a></span>
</figcaption>
</figure>
<h2>Magnetic traces build a map</h2>
<p>Using the average magnetic direction of the whole suite of samples we can calculate their ancient latitude, which we refer to as the paleolatitude.</p>
<p>The original single-stage collision model for the Himalaya predicts that these rocks would have formed close to Eurasia at a latitude of around 20 degrees north, but our data shows that these rocks did not form on either the Indian or the Eurasian continents. Instead, they formed on a chain of volcanic islands, out in the open Neotethys Ocean at a latitude of about 8 degrees north, thousands of kilometers south of where Eurasia was located at the time.</p>
<p>This finding can be explained only if there were <a href="https://doi.org/10.1038/ngeo2418">two subduction zones</a> pulling India rapidly toward Eurasia, rather than just one. </p>
<p>[<em>You’re smart and curious about the world. So are The Conversation’s authors and editors.</em> <a href="https://theconversation.com/us/newsletters/weekly-highlights-61?utm_source=TCUS&utm_medium=inline-link&utm_campaign=newsletter-text&utm_content=weeklysmart">You can get our highlights each weekend</a>.]</p>
<p>During a geologic time period known as the Paleocene, India caught up with the volcanic island chain and collided with it, scraping up the rocks we eventually sampled onto the northern edge of India. India then continued northward before <a href="https://doi.org/10.1016/j.epsl.2013.01.023">ramming into Eurasia around 40 to 45 million years ago</a> – 10 to 15 million years later than was generally thought.</p>
<p>This final continental collision raised the volcanic islands from sea level up over 4,000 meters to their present-day location, where they form jagged outcrops along a spectacular Himalayan mountain pass.</p><img src="https://counter.theconversation.com/content/148404/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Craig Robert Martin receives funding from the National Science Foundation (NSF).</span></em></p>Earth’s magnetic field locks information into lava as it cools into rock. Millions of years later, scientists can decipher this magnetic data to build geologic timelines and maps.Craig Robert Martin, Ph.D. Student in Earth, Atmospheric and Planetary Sciences, Massachusetts Institute of Technology (MIT)Licensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1234282020-01-06T12:06:32Z2020-01-06T12:06:32ZA new way to identify a rare type of earthquake in time to issue lifesaving tsunami warnings<figure><img src="https://images.theconversation.com/files/308024/original/file-20191219-11946-1t4d9ok.jpg?ixlib=rb-1.1.0&rect=350%2C0%2C5065%2C3700&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">This unusual earthquake type generates an outsized tsunami. </span> <span class="attribution"><a class="source" href="https://unsplash.com/photos/1fEYDfuGli0">camila castillo/Unsplash</a>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span></figcaption></figure><p>Just a few times in a century, somewhere on the globe, a rare “tsunami earthquake” occurs. These are mysterious because, while they’re just medium-sized as earthquakes go, they cause disproportionately large and devastating tsunamis. This type of midsized earthquake is very different than an event like the <a href="http://www.tectonics.caltech.edu/outreach/highlights/sumatra/what.html">2004 earthquake in Sumatra</a> – a very big magnitude 9.2 event which unsurprisingly produced a huge tsunami.</p>
<p>The most recent tsunami earthquake happened in 2010. <a href="https://doi.org/10.1029/2010GL046552">A magnitude 7.8 earthquake</a> <a href="http://itic.ioc-unesco.org/index.php?option=com_content&view=article&id=1673:301&catid=1444&Itemid=1444">off the Mentawai Islands in Indonesia</a> <a href="https://doi.org/10.1029/2010GL046498">set off a tsunami</a> that was <a href="https://doi.org/10.1029/2012JB009159">over 50 feet in height</a> in some places – much greater than seismologists would predict based just on the earthquake’s size. <a href="https://earthobservatory.sg/outreach/natural-hazard-outreach/west-sumatra-tectonics-and-tsunami-hazard">509 people were killed</a>, and 15,000 more were displaced or left homeless. </p>
<p>Tsunami earthquakes are particularly destructive and dangerous because the massive tsunami waves can hit local coastal communities within just five to 15 minutes – before officials can issue a warning. But <a href="https://doi.org/10.1029/2019GL083989">based on our analysis</a> of previously unavailable closeup observations of the 2010 Mentawai event, my colleagues <a href="https://scholar.google.com/citations?user=8YD_3R8AAAAJ&hl=en&oi=ao">and I</a> think there is a way to determine that an event is a tsunami earthquake in time to warn people that an unexpectedly large wave is on the way.</p>
<h2>Earthquakes under the ocean</h2>
<p>The Earth’s surface is made up of <a href="https://theconversation.com/plate-tectonics-new-findings-fill-out-the-50-year-old-theory-that-explains-earths-landmasses-55424">floating tectonic plates</a> that fit together like a slightly imperfect jigsaw puzzle. These plates are moving next to, under or away from each other.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/308389/original/file-20200102-11904-tusj3g.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/308389/original/file-20200102-11904-tusj3g.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/308389/original/file-20200102-11904-tusj3g.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=372&fit=crop&dpr=1 600w, https://images.theconversation.com/files/308389/original/file-20200102-11904-tusj3g.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=372&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/308389/original/file-20200102-11904-tusj3g.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=372&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/308389/original/file-20200102-11904-tusj3g.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=467&fit=crop&dpr=1 754w, https://images.theconversation.com/files/308389/original/file-20200102-11904-tusj3g.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=467&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/308389/original/file-20200102-11904-tusj3g.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=467&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">An earthquake along a subduction zone happens when the leading edge of the overriding plate breaks free and springs seaward, raising the seafloor and the water above it. This uplift starts a tsunami.</span>
<span class="attribution"><a class="source" href="https://www.usgs.gov/media/images/earthquake-starts-tsunami">USGS</a></span>
</figcaption>
</figure>
<p>In <a href="https://www.livescience.com/43220-subduction-zone-definition.html">a subduction zone</a>, one tectonic plate is sinking beneath another. This builds up stresses over time and will eventually create an earthquake. Most typical subduction-zone earthquakes occur roughly 10 to 30 miles down, in an area where the rocks are rigid and strong on the fault between the two tectonic plates.</p>
<p>Meanwhile, the shallowest area of a subduction zone, closest to the seafloor, is made up of soft sediments that are not very strong. Earthquakes rarely occur only here, because stresses mostly don’t build up in these soft, weak rocks.</p>
<p>Geoscientists define an earthquake’s overall size with its magnitude. Earthquake magnitude describes how much “work” is accomplished by the earthquake moving the fault – more work for either more movement, or for moving more rigid rock.</p>
<p>Very large earthquakes, like the magnitude 9 Tohoku earthquake in Japan in 2011, are so big that they break the deeper part of the subduction zone, but also continue upwards to break the shallow part of a subduction zone. This rapid earthquake motion moves the seafloor and <a href="https://www.iris.edu/hq/inclass/animation/subduction_zone_tsunamis_generated_by_megathrust_earthquakes">creates a tsunami</a>.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/293875/original/file-20190924-51434-1ytyrz6.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/293875/original/file-20190924-51434-1ytyrz6.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/293875/original/file-20190924-51434-1ytyrz6.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=267&fit=crop&dpr=1 600w, https://images.theconversation.com/files/293875/original/file-20190924-51434-1ytyrz6.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=267&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/293875/original/file-20190924-51434-1ytyrz6.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=267&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/293875/original/file-20190924-51434-1ytyrz6.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=336&fit=crop&dpr=1 754w, https://images.theconversation.com/files/293875/original/file-20190924-51434-1ytyrz6.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=336&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/293875/original/file-20190924-51434-1ytyrz6.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=336&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Cartoon depicting the amount of movement in five earthquakes. The 2010 Mentawai tsunami earthquake moved the fault much more – over 65 feet compared to about 15 feet for the others – and the movement occurred much closer to the seafloor than in any of the other earthquakes.</span>
<span class="attribution"><span class="source">Sahakian et al. (2019), GRL</span></span>
</figcaption>
</figure>
<h2>What sets tsunami quakes apart</h2>
<p>“Tsunami earthquakes” are strange in that they happen almost entirely in the soft, weak section of the fault.</p>
<p>Because tsunami earthquakes break such soft rock, they happen slower, and create much more movement on or near the seafloor in comparison to a normal subduction-zone earthquake of the same size that happens in rigid rock. This in turn creates a much larger tsunami than expected. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/306913/original/file-20191214-85412-1b87exs.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/306913/original/file-20191214-85412-1b87exs.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/306913/original/file-20191214-85412-1b87exs.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=314&fit=crop&dpr=1 600w, https://images.theconversation.com/files/306913/original/file-20191214-85412-1b87exs.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=314&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/306913/original/file-20191214-85412-1b87exs.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=314&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/306913/original/file-20191214-85412-1b87exs.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=395&fit=crop&dpr=1 754w, https://images.theconversation.com/files/306913/original/file-20191214-85412-1b87exs.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=395&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/306913/original/file-20191214-85412-1b87exs.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=395&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Seismograms showing how much the ground shook from six similarly sized earthquakes, at seismometers all about the same distance from their earthquake. You’d expect the shaking to be comparable. The 2010 Mentawai earthquake seismogram is at the bottom in orange, and shows significantly less shaking than any of the others.</span>
<span class="attribution"><span class="source">Modified from Sahakian et al. (2019), GRL.</span></span>
</figcaption>
</figure>
<p>A tsunami earthquake might have the same magnitude as an earthquake that occurs in rigid rock but produces much less of what seismologists call high-frequency energy. </p>
<p>Think of breaking a thick slab of concrete – which is strong and would produce an audible bang with both low and high-pitched noise – versus breaking a loaf of bread, which makes almost no sound at all. In the Earth, “sound” is the shaking you feel under your feet. The soft bread break is like a tsunami earthquake that doesn’t release a lot of high-frequency energy, and thus doesn’t create as much shaking as we would expect for its magnitude.</p>
<h2>Sensing quakes in time to warn</h2>
<p>Currently, officials rely on knowing an earthquake’s magnitude and location to issue tsunami warnings within tens of minutes. But this doesn’t work in the case of tsunami earthquakes, because the earthquake’s magnitude doesn’t match up with the size of the tsunami it produces.</p>
<p>Instead, to figure out whether an earthquake is in fact a tsunami earthquake, scientists compare its seismic magnitude measured from afar with the amount of high frequency radiated energy it produced, as recorded by far away stations.</p>
<p>If the ratio of energy to magnitude is very low, it’s a tsunami earthquake – basically, its shaking was far too weak for its magnitude because it was breaking soft rock. Instead, its energy is of the low-frequency type: Rather than strong shaking, its energy goes into large slow movement of the seafloor and the ensuing tsunami.</p>
<p>The problem is that in the past, scientists had never recorded one of these elusive earthquakes closeup in what we call the near-field – within about 180 miles (300 kilometers) or so. Instead, scientists have had to find an earthquake’s energy-to-magnitude ratio using seismic waves that have traveled all the way from the epicenter of the earthquake across the world to where researchers can measure them. This process is relatively slow, so we haven’t been able to identify tsunami earthquakes quickly enough to warn people in time, before the wave hits the coast.</p>
<p>Now my colleagues and I have for the first time analyzed data recorded by seismic stations that happened to be near the epicenter of the 2010 Mentawai earthquake. We think we have figured out a new way to identify the danger of a future tsunami earthquake, faster.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/308439/original/file-20200103-11951-8wlrvt.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/308439/original/file-20200103-11951-8wlrvt.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/308439/original/file-20200103-11951-8wlrvt.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/308439/original/file-20200103-11951-8wlrvt.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/308439/original/file-20200103-11951-8wlrvt.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/308439/original/file-20200103-11951-8wlrvt.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/308439/original/file-20200103-11951-8wlrvt.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/308439/original/file-20200103-11951-8wlrvt.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Tsunamis can take a terrible toll, as for this Indonesian family that lost their father and their home in the Mentawai disaster.</span>
<span class="attribution"><a class="source" href="http://www.apimages.com/metadata/Index/Indonesia-Disasters/77a6343c59ee46199456933fc238e848/4/0">AP Photo/Tundra Laksamana</a></span>
</figcaption>
</figure>
<h2>Closer and quicker proxies</h2>
<p>Our new study used the same concept of comparing the energy released by an earthquake to its seismic magnitude – but based on data from geographically close to the event. Instead of looking at energy measurements recorded at a distance, we used two proxies.</p>
<p>To look directly at how much the ground shook, we used seismic stations onshore near the epicenters of 16 earthquakes, including the Mentawai one in 2010. Because the amount the ground accelerates when seismic waves pass through illustrates how much high frequency energy is in the earthquake, this information was a stand-in for the data we would traditionally get from the far-flung teleseismic stations. Low accelerations mean little high frequency energy.</p>
<p>For the normal earthquakes we looked at, the accelerations from near-field seismometers were close to what we’d expect for each earthquake’s magnitude. In comparison, the 2010 Mentawai earthquake’s accelerations were closer to what we would expect for a magnitude 6.3 earthquake – whereas the earthquake was actually a magnitude 7.8, and produced a tsunami we’d expect for an event of greater than magnitude 8.</p>
<p>We also looked at GPS stations close to the earthquakes. They can show us how much the ground actually moved or was displaced, and measure the earthquake magnitude itself.</p>
<p>Using these measurements together allowed us to compare the amount of energy in the earthquake with respect to its magnitude – without waiting for the seismic waves to travel across the globe. Instead, we would have been able to identify a tsunami earthquake immediately by looking at how low the accelerations were on local seismometers in comparison to the magnitude of the earthquake based on GPS readings.</p>
<p>We think our finding is really promising because these near-field measurements are available immediately – even while an earthquake is happening. Seismologists could use this approach in the future, to identify a tsunami earthquake right after it happens, and provide warning to the nearby coast before the tsunami wave arrives.</p>
<p>[ <em>Deep knowledge, daily.</em> <a href="https://theconversation.com/us/newsletters?utm_source=TCUS&utm_medium=inline-link&utm_campaign=newsletter-text&utm_content=deepknowledge">Sign up for The Conversation’s newsletter</a>. ]</p><img src="https://counter.theconversation.com/content/123428/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Valerie Sahakian does not work for, consult, own shares in or receive funding from any company or organization that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>A tricky kind of earthquake that happens in the soft rock of the ocean floor causes much larger tsunamis than their magnitude would predict. New research pinpoints a way to identify the danger fast.Valerie Sahakian, Assistant Professor of Geophysics, University of OregonLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/904082018-01-24T09:13:41Z2018-01-24T09:13:41ZEthiopia could be sitting on one of world’s great untapped gold deposits<figure><img src="https://images.theconversation.com/files/202850/original/file-20180122-182973-17q25f.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/ethiopian-cents-image-lion-head-isolated-716736049?src=MqPalwucGkqsIEJJ26g5Iw-2-42">Andrey Lobachev</a></span></figcaption></figure><p>To the west of Ethiopia near the Sudanese border lies a place called the Asosa zone. This may be the location of the oldest gold mine in the world. Dating back some 6,000 years, it provided a key source of gold to the ancient Egyptian empire, whose great wealth was famous throughout the known world. It may even have supplied the Queen of Sheba with her lavish gifts of gold when she visited King Solomon of Israel almost 3,000 years ago. </p>
<p>The excitement in this part of the world is more about the future, however. Some local inhabitants already make a living from prospecting, and several mining companies have been active in the area in recent years, too. </p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/202851/original/file-20180122-182948-2y98r4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/202851/original/file-20180122-182948-2y98r4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/202851/original/file-20180122-182948-2y98r4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=752&fit=crop&dpr=1 600w, https://images.theconversation.com/files/202851/original/file-20180122-182948-2y98r4.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=752&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/202851/original/file-20180122-182948-2y98r4.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=752&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/202851/original/file-20180122-182948-2y98r4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=945&fit=crop&dpr=1 754w, https://images.theconversation.com/files/202851/original/file-20180122-182948-2y98r4.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=945&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/202851/original/file-20180122-182948-2y98r4.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=945&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">When Sheba met Sol.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/ethiopian-cents-image-lion-head-isolated-716736049?src=MqPalwucGkqsIEJJ26g5Iw-2-42">Wikimedia</a></span>
</figcaption>
</figure>
<p>But what comes next could be on a much bigger scale: I have just co-published with my colleague, Owen Morgan, <a href="https://abdn.pure.elsevier.com/en/publications/the-asosa-region-of-western-ethiopia-a-golden-exploration-opportu">new geological research</a> that suggests that much more treasure might be buried under the surface of this east African country than was previously thought. </p>
<h2>Treasure trail</h2>
<p>The Asosa zone is made up of flatlands, rugged valleys, mountainous ridges, streams and rivers. It is densely vegetated by bamboo and incense trees, with remnants of tropical rainforests along the river valleys. The zone, which is part of Ethiopia’s Benishangul-Gumuz region, is spotted with <a href="https://web.stanford.edu/dept/archaeology/journal/04GonzalezFernandez.pdf">archaeological sites</a> containing clues to how people lived here thousands of years ago, together with ancient mining pits and trenches. </p>
<p>Local inhabitants have long taken advantage of these riches. They pan for gold in Asosa’s streams and also extract the precious metal directly from outcropping rocks. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/202822/original/file-20180122-46210-1ei2jtm.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/202822/original/file-20180122-46210-1ei2jtm.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/202822/original/file-20180122-46210-1ei2jtm.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=544&fit=crop&dpr=1 600w, https://images.theconversation.com/files/202822/original/file-20180122-46210-1ei2jtm.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=544&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/202822/original/file-20180122-46210-1ei2jtm.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=544&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/202822/original/file-20180122-46210-1ei2jtm.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=684&fit=crop&dpr=1 754w, https://images.theconversation.com/files/202822/original/file-20180122-46210-1ei2jtm.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=684&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/202822/original/file-20180122-46210-1ei2jtm.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=684&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Local inhabitants panning for gold.</span>
<span class="attribution"><span class="source">Owen Morgan</span></span>
</figcaption>
</figure>
<p>More substantial exploitation of the region’s riches dates back to the Italian invasion of the 1930s. The Italians explored the Welega gold district in West Welega, south-east of Asosa. </p>
<p>Haile Selassie, emperor of Ethiopia from 1930 to 1974, believed the country had the potential to become a global leader in gold. But when the revolutionary Derg government deposed him and the country plunged into civil war, gold mining disappeared off the agenda for a decade and a half. It took until the early 2000s before the government started awarding exploration licences. </p>
<p>Several mines are up and running, neither of them in Asosa. One is at Lega Dembi slightly to the east, owned by Saudi interests. <a href="https://hornaffairs.com/2017/08/28/new-gold-mines-in-shire-wollega-tulukapi-as-illicit-trade-rises/">The other</a>, at Tigray in the north of the country, is owned by American mining giant Newmont, and just started production late last year. </p>
<p>More is already on the way: the beneficiary of the Italian efforts from the 1930s in Welega is the Tulu Kapi gold prospect, containing 48 tonnes of gold. This was <a href="http://www.kefi-minerals.com/strategy">most recently acquired</a> in 2013 by Cyprus-based mining group KEFI Minerals (market value: roughly US$2.3 billion (£1.7 billion)). </p>
<p>As for Asosa, the Egyptian company ASCOM made a significant gold discovery in the zone in 2016. It <a href="https://enterprise.press/stories/2016/06/12/qalaa-seeks-gold-in-ethiopia/">published</a> a maiden resource statement that claimed the presence of – curiously the same number – 48 tonnes of gold. Yet this only looks like the beginning. </p>
<h2>Au-some potential?</h2>
<p>The Asosa zone geology is characterised by various kinds of volcanic and sedimentary rocks that are more than 600 million-years-old. The region has been intensely deformed by geological forces, resulting in everything from kilometre-long faults to tiny cracks known as veins which are only centimetres in length. </p>
<p>Some of these veins contain quartz, and it is mainly here that the region’s gold accumulated between 615m and 650m years ago – along with silver and various other minerals. The gold came from molten materials deep within the Earth finding their way upwards during a process known as <a href="https://theconversation.com/continents-may-not-have-been-created-in-the-way-we-thought-33334">subduction</a>, where tectonic forces drive oceanic crust beneath a continent. This is comparable to the reasons behind gold deposits in <a href="http://bullmarketrun.com/wp-content/uploads/2015/07/Sillitoe-2000-Gold-Rich-Porphyry-Deposits.pdf">island arcs</a> like some of <a href="http://www.sciencedirect.com/science/article/pii/0375674295000276">the ones</a> in Indonesia and Papua New Guinea. </p>
<p>Our field observations and panning <a href="https://abdn.pure.elsevier.com/en/publications/the-asosa-region-of-western-ethiopia-a-golden-exploration-opportu">suggest that</a> gold should be generally abundant across the Asoza zone – both in quartz veins but also elsewhere in the schist and pegmatite rocks in which they are located. We also see signs of substantial graphite deposits, which are important for everything from touch-screen tablets to lithium-ion batteries. </p>
<p>There is undoubtedly much more world-class gold within this area than has already been discovered, pointing to a promising source of income for the government for years to come – much of the region remains unexplored, after all. It probably is no exaggeration to say that Ethiopia’s gold potential could rival South Africa’s, which would put it somewhere around the <a href="https://financesonline.com/top-10pgold-producing-countries-in-the-world/">top five</a> gold producing nations in the world. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/202820/original/file-20180122-46232-qea4pz.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/202820/original/file-20180122-46232-qea4pz.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/202820/original/file-20180122-46232-qea4pz.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=420&fit=crop&dpr=1 600w, https://images.theconversation.com/files/202820/original/file-20180122-46232-qea4pz.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=420&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/202820/original/file-20180122-46232-qea4pz.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=420&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/202820/original/file-20180122-46232-qea4pz.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=528&fit=crop&dpr=1 754w, https://images.theconversation.com/files/202820/original/file-20180122-46232-qea4pz.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=528&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/202820/original/file-20180122-46232-qea4pz.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=528&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">View across the gold-bearing schist rocks of the Asosa zone, Benishangul-Gumuz.</span>
<span class="attribution"><span class="source">Owen Morgan</span></span>
</figcaption>
</figure>
<p>There are still some substantial challenges, however. Dealing with governmental red tape can be difficult. In an area like the Asosa zone there are dangerous wildlife to avoid, such as venimous snakes, baboons and even monkeys. The vegetation also becomes forbiddingly wild during wet seasons. </p>
<p>It is also important to strike up good working relationships with local inhabitants, showing the utmost respect to local cultures – it’s the ethical way to operate, and failing to do so can make life harder with the authorities in the capital. This includes the need to preserve the natural beauty of the region; gold mining already has a very bad <a href="https://www.smithsonianmag.com/science-nature/environmental-disaster-gold-industry-180949762/">international reputation</a> for environmental damage. </p>
<p>With the right approach, however, western Ethiopia will be a literal gold mine that could bring economic benefit to the region. What the Queen of Sheba may have known 3,000 years ago, the modern world is finally rediscovering today.</p><img src="https://counter.theconversation.com/content/90408/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Liam Bullock was previously employed by GP Resource Mining Ltd (UK) (2015-2016), who worked in partnership with Tactical Environmental Response Ltd (UK) and GP Resource Mining PLC (Ethiopia), who previously held licences to explore for gold in Asosa. </span></em></p>Hailie Selassie thought his country’s gold could rival the biggest deposits in the world. He may be proven right.Liam Bullock, Research Fellow, University of AberdeenLicensed as Creative Commons – attribution, no derivatives.