地幔过渡带和下地幔组成与深部热源研究进展

Research Advance in Materials of Transition Zone-Lower Mantle and Deep Heat Sources

受时空不可及性的制约,地质学家在探究地球深部物质组成方面仍显得很被动,尤其是在探究地幔物质组成方面显得更加艰难。目前,科学家们探测地幔物质主要依靠地球物理学和实验矿物学、岩石学方法相结合的手段来进行。结果表明,地幔过渡带主要的矿物组成有瓦士利石、林伍德石、超硅石榴子石以及少量的CaSiO3。下地幔主要矿物组成有钙钛矿(Pv)、后钙钛矿(PPv)和镁方铁矿(Mw)。在讨论过渡带和下地幔物质组成的基础上,归纳总结了地球内部热源的三种来源,分别是放射性元素的衰变热和初始熔融硅酸盐地球长期冷却放出的热、核幔边界在地磁场和高电导率物质的作用下产生的热以及来自地核的热。这些结论对研究地球深部动力学和热力学过程有重要意义。

It is difficult to explore chemical compositions of the Earth＇s interiors, especially the mantle, since of their spatial-temporal unreachability. Nowadays, scientists investigate the chemical compositions of the mantle by the approaches of geophysics and experimental mineralogy and petrology. The results obtained by the three methods indicated that the mantle transition zone mainly consists of wadsleyite, Ringwoodite, majorite, and small quantity of CaSiO3-perovskite, and that the lower mantle mainly consists of perovskite, post-peroskite, and magnesiowiistite. On the basis of the investigation of compositions of mantle transition zone and lower mantle, heat sources in the Earth＇s interior are proposed as following： 1） decay of radioactive elements and cooling of the primitive melting silicate Earth, 2） interaction of high electrical conductivity materials and the magnetic field of the Earth, 3） the Earth＇s core. These conclusions are of great importance in better understanding of geodynamic and thermodynamic processes in the deep interior of the Earth.