Genady Posted December 28, 2021 Share Posted December 28, 2021 Oh, the headline writers ... Scientists Find A Hole In Earth’s Centre, Through A Secret Duct Under Panama (indiatimes.com) Link to comment Share on other sites More sharing options...
exchemist Posted December 28, 2021 Share Posted December 28, 2021 (edited) 22 minutes ago, Genady said: Oh, the headline writers ... Scientists Find A Hole In Earth’s Centre, Through A Secret Duct Under Panama (indiatimes.com) Indeed. Seems they've found anomalous Helium isotope ratios in hot springs in Panama that are consistent with the material coming up from the mantle at the Galapagos hotspot, even though these Panama locations are hundreds of km away and, moreover, on the far side of the subducting slab of the Cocos plate that lies in between. So a hole or break in the subducting plate is to be presumed. But, er, not "a hole in Earth's centre", whatever that might be supposed to mean! Here is the abstract of the PNAS paper: It is well established that mantle plumes are the main conduits for upwelling geochemically enriched material from Earth's deep interior. The fashion and extent to which lateral flow processes at shallow depths may disperse enriched mantle material far (>1,000 km) from vertical plume conduits, however, remain poorly constrained. Here, we report He and C isotope data from 65 hydrothermal fluids from the southern Central America Margin (CAM) which reveal strikingly high 3He/4He (up to 8.9RA) in low-temperature (≤50 °C) geothermal springs of central Panama that are not associated with active volcanism. Following radiogenic correction, these data imply a mantle source 3He/4He >10.3RA (and potentially up to 26RA, similar to Galápagos hotspot lavas) markedly greater than the upper mantle range (8 ± 1RA). Lava geochemistry (Pb isotopes, Nb/U, and Ce/Pb) and geophysical constraints show that high 3He/4He values in central Panama are likely derived from the infiltration of a Galápagos plume–like mantle through a slab window that opened ∼8 Mya. Two potential transport mechanisms can explain the connection between the Galápagos plume and the slab window: 1) sublithospheric transport of Galápagos plume material channeled by lithosphere thinning along the Panama Fracture Zone or 2) active upwelling of Galápagos plume material blown by a “mantle wind” toward the CAM. We present a model of global mantle flow that supports the second mechanism, whereby most of the eastward transport of Galápagos plume material occurs in the shallow asthenosphere. These findings underscore the potential for lateral mantle flow to transport mantle geochemical heterogeneities thousands of kilometers away from plume conduits. Edited December 28, 2021 by exchemist 1 Link to comment Share on other sites More sharing options...
Bufofrog Posted December 28, 2021 Share Posted December 28, 2021 (edited) This headline isn't science. Edited to add "headline". Edited December 28, 2021 by Bufofrog Link to comment Share on other sites More sharing options...
exchemist Posted December 28, 2021 Share Posted December 28, 2021 2 minutes ago, Bufofrog said: This isn't science. I hope my explanation, which crossed with your post, does a bit better........ Link to comment Share on other sites More sharing options...
studiot Posted December 28, 2021 Share Posted December 28, 2021 1 hour ago, exchemist said: Indeed. Seems they've found anomalous Helium isotope ratios in hot springs in Panama that are consistent with the material coming up from the mantle at the Galapagos hotspot, even though these Panama locations are hundreds of km away and, moreover, on the far side of the subducting slab of the Cocos plate that lies in between. So a hole or break in the subducting plate is to be presumed. But, er, not "a hole in Earth's centre", whatever that might be supposed to mean! Here is the abstract of the PNAS paper: It is well established that mantle plumes are the main conduits for upwelling geochemically enriched material from Earth's deep interior. The fashion and extent to which lateral flow processes at shallow depths may disperse enriched mantle material far (>1,000 km) from vertical plume conduits, however, remain poorly constrained. Here, we report He and C isotope data from 65 hydrothermal fluids from the southern Central America Margin (CAM) which reveal strikingly high 3He/4He (up to 8.9RA) in low-temperature (≤50 °C) geothermal springs of central Panama that are not associated with active volcanism. Following radiogenic correction, these data imply a mantle source 3He/4He >10.3RA (and potentially up to 26RA, similar to Galápagos hotspot lavas) markedly greater than the upper mantle range (8 ± 1RA). Lava geochemistry (Pb isotopes, Nb/U, and Ce/Pb) and geophysical constraints show that high 3He/4He values in central Panama are likely derived from the infiltration of a Galápagos plume–like mantle through a slab window that opened ∼8 Mya. Two potential transport mechanisms can explain the connection between the Galápagos plume and the slab window: 1) sublithospheric transport of Galápagos plume material channeled by lithosphere thinning along the Panama Fracture Zone or 2) active upwelling of Galápagos plume material blown by a “mantle wind” toward the CAM. We present a model of global mantle flow that supports the second mechanism, whereby most of the eastward transport of Galápagos plume material occurs in the shallow asthenosphere. These findings underscore the potential for lateral mantle flow to transport mantle geochemical heterogeneities thousands of kilometers away from plume conduits. If this was an extract, thank you. I have substantial doubts about some of the results and conclusions however. The question of why it is necessary to consider transport mechanisms at all arises immediately. What chemical or radiochemical process generates helium ? Why can this not work just as well in Panama as in the Galapagos ? If the 'geothermal water in Panama is not volcanically heated, why is it hot ? Link to comment Share on other sites More sharing options...
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