Introduction In his lectures on Earth

Introduction In his lectures on Earth geological age Lord Kelvin (Thomson, 1868) estimated by calculations that the birth of Earth took place around 100 million years ago. For this first estimation the Earth was assumed to be originally formed of a completely molten object following the idea of Leibniz (1691). Kelvin determined the time it would take for the near-surface to cool to its present temperature. Calculations did not account for heat produced via convection, dacomitinib or a natural geo-reactor inside the Earth. Since then, natural geo-reactors have been postulated at various locations in the Earth and discovered within the Earth crust: The aim of the present study is to revisit the concept of geo-reactor considering the physical chemical conditions induced and occurring at the CMB and in the core by hypothetical actinide (An) stratification. The study also completes the picture by considering thorium as a potential fertile element, taking into account all fissile actinides and their breeding in the geo-reactor. The potential geo-reactor power expressed in TW is compared with the other heat flux densities and Earth heat source data.
Argumentation supporting the occurrence of the geo-reactor
Assessment of the geo-reactor physical and chemical processes In order to evaluate the geo-reactor build-up mechanism, both preliminary reference Earth model (PREM) as developed by Dziewonski and Anderson (1981) and Geochemical Earth Reference Model (GERM) provided by Staudigel et al. (1998) may be used together with advanced coupling models. The geo-reactor build-up requires specific actinide phase formation with a density difference within the local molten phases.
Discussion
Conclusions
Introduction Molybdenum (Mo) is one of the most important elements for modern society because of its variable properties that allow it to make materials ranging from super-hard alloys to solid lubricants. There are three main types of Mo deposits, high-F porphyry Mo, low-F porphyry Mo, and porphyry Cu–Mo deposits. Remarkably, half of the world\'s Mo resources are hosted in Cenozoic porphyries along the east Pacific margin (Fig. 1). In contrast, there are hardly any large Mo deposits along the west Pacific margin, whereas more than one third of the world\'s Mo sources are hosted in Cretaceous porphyry Mo deposits in the Triassic Qinling-Dabie orogenic belt (Chen et al., 2000; Li et al., 2012, 2007; Zhang et al., 2014). The formation of Mo deposits along the west coast of the North and South American continents has been attributed to different mechanisms: melting of underplated mafic/ultramafic rocks or intermediate crustal/organic-poor sedimentary rocks (Stein et al., 2001); addition of ore-forming fluids from large Mo enriched magma chambers that crystallized and fractionated in the lower crust or at mid-crustal levels well below the porphyry Mo deposits (Klemm et al., 2008), or subduction-related magmatism (Ludington et al., 2009). However, the details of the mechanism that enriched Mo within a short period of time in such a limited space remain obscure. Here we show that subducted Mo-enriched sediments, which formed during Oceanic Anoxic Events (OAEs), were responsible for the large Mo deposit belt along the eastern Pacific margin. Metamorphism of Mo-rich sediments during subduction is another key factor that controls porphyry Mo deposits.
Molybdenum enrichment Molybdenum is a very rare element with an abundance of only ∼50 parts per billion (ppb) in the silicate Earth (McDonough and Sun, 1995), which is only ∼0.1% of that of Cu. As a moderately incompatible chalcophile element, Mo is enriched in the continental crust during mantle magmatic processes (McDonough and Sun, 1995; Sun and McDonough, 1989; Sun et al., 2003b), but only by a factor of ∼15 compared to the primitive mantle (Rudnick and Gao, 2003) to a level of ∼0.8 parts per million (ppm). Nonetheless, Mo forms independent porphyry-Mo deposits with grades up to 0.3% of Mo metal, which is more than 3500 times higher than its abundance in the continental crust. Considering the similarities of Mo and Cu during magmatism and hydrothermal processes, it is surprising that the Mo concentration can be increased by more than 3 orders of magnitude during magmatic and/or hydrothermal processes without concomitant enrichment of Cu.