铀占地核的百分比是多少?-地江南体育网页版球科学堆栈交换江南电子竞技平台 最近30个来自www.hoelymoley.com 2023 - 03 - 25 - t21:13:56z //www.hoelymoley.com/feeds/question/4798 https://creativecommons.org/licenses/by-sa/4.0/rdf //www.hoelymoley.com/q/4798 22 铀占地核的百分比是多少? 史蒂夫Farkus //www.hoelymoley.com/users/2866 2015 - 05 - 03 - t14:16:47z 2023 - 02 - 11 - t01:54:57z

地核有百分之多少是铀?核心的热量有多少来自放射性衰变而不是其他力量?< / p >

 //www.hoelymoley.com/questions/4798/-/4802#4802 30. 地球核中铀的比例是多少? 大卫Hammen //www.hoelymoley.com/users/239 2015 - 05 - 03 - t21:08:02z 2020 - 09 - 23 - t08:53:02z < p >好问题!地球化学家和地球物理学家求同存异，有时甚至非常强烈。每个小组内部以及两个小组之间也存在分歧。

不仅仅是铀。有四种同位素，它们的半衰期足够长，可以是原初的，而它们的半衰期又不是很长，不能产生太多的热量。这四种同位素分别是

  • 铀235，半衰期为7.03亿年，
  • 钾40，半衰期为12.77亿年，
  • 铀238，半衰期为44.68亿年，
  • 钍232，半衰期为140.56亿年。地球化学家之间的共识是，在地核中，这些同位素即使有，也很少。钾、钍和铀具有化学活性。它们很容易氧化。事实上，它们很容易与许多其他元素化学结合——但不包括铁。它们是强烈的亲石元素。此外，这三者是“不相容的”; elements. In a partial melt, they have a strong affinity to stay in the molten state. This means that relative to solar system abundances, all three of these elements should be strongly enhanced in the Earth's crust, slightly depleted in the Earth's mantle, and strongly depleted in the Earth's core.

    Geophysicists look at the amount of heat needed to drive the Earth's magnetic field, and at the recent results from neutrino observations. From their perspective, the amount of residual heat from the Earth's formation is not near enough to drive the geomagneto. The growth of the Earth's inner core creates some heat, but not near enough to sustain the geodynamo. Geophysicists want a good amount of heat flux across the core mantle boundary to sustain the geodynamo, and to them the only viable source is radioactivity. Recent geoneutrino experiments appear to rule out uranium or thorium in the Earth's core, but not potassium 40. The neutrinos generated from the decay of potassium 40 are not detectable using current technology.

 //www.hoelymoley.com/questions/4798/-/6557#6557 2 地球核中铀的比例是多少? 戈登斯坦格 //www.hoelymoley.com/users/4507 2015 - 09 - 18 - t08:50:06z 2015 - 09 - 18 - t08:50:06z 他是对的，在地核中几乎没有珍贵的铀或钍。他还说对了，需要一个额外的热源来驱动地核的磁性。然而，请注意，正如长期以来所知道的那样，地核的密度小于纯Ni-Fe合金的情况。答案是，那里有大量的硫，实际上约占月球重量的10%，它们很可能以高压硫化铁相的形式存在。钾是一种亲石元素，通常不存在于岩心中，但钾可溶于硫化铁。放射性核素40-钾，在硫化物中，在核心，是缺失的热量的来源，驱动发电机，创造了地球磁场超过35亿年。< / p > //www.hoelymoley.com/questions/4798/-/24777#24777 3. 地球核中铀的比例是多少? 奥斯卡Lanzi //www.hoelymoley.com/users/20607 2023 - 01 - 23 t01:48:32z 2023 - 02 - 11 - t01:54:57z 一种可能是存在足够多的铀来提供一个大量的热源——在地幔深处，而不是地核。< / p >

Gautron et al.[1] study the inclusion of uranium in an aluminum-doped calcium silicate perovskite, which is believed to exist in the lower mantle (the authors cite Ref. 2). With the aluminum doping, the silicate perovskite becomes compatible with uranium(IV), and thereby "all the uranium present in this region could be easily stored via its insertion in the Al-CaSiO3 perovskite." The authors suggest that thorium, which also favors the +4 oxidation state and forms a similarly large cation, may similarly be incorporated, although they directly studied only uranium.

References

  1. Laurent Gautron, Steeve Greaux, Denis Andrault, Nathalie Bolfan-Casanova, Nicolas Guignot, M. Ali Bouhifd (2006). "Uranium in the Earth's lower mantle". Geophysical Research Letters 33(23), L23301. https://doi.org/10.1029/2006GL027508.

  2. Hirose, K. (2002). "Phase transitions in the pyrolitic mantle around 670–km depth: Implications of upwellings of plumes from the lower mantle". J. Geophys. Res., 107(B4), 2078. https://doi.org/10.1029/2001JB000597.
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