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地球板块构造是怎样开始的?

板块构造理论,描述了地球的岩石圈是由不同的板块,能够在底层的软流圈。在板块边界,这个运动能增加收敛可能发生俯冲边界,不同的边界,在熔岩上升不同板块之间以填补空白,或滑动板变换边界。

虽然我理解为什么我们已经采用这一理论,我不清楚的是为什么地球的岩石圈是由不同的板块首先,和有可能对现有板块分成两个截然不同的盘子吗?有一个理论在地球板块最初是如何形成的?

回答

>有一个理论在地球板块最初是如何形成的?这是源于另一个问题的答案你问到大陆地壳和海洋地壳之间的区别。[卡尔森et al . (2014)] (http://www.annualreviews.org/doi/abs/10.1146/annurev -地球- 060313 - 055016)刚刚发表了一个优秀的回顾我们所知道的关于地球和它是如何形成的。我用它作为一个指导和这篇文章的来源。就在最近一个锆石的年龄确定为4.374 Ga((山谷et al ., 2014) (http://www.news.wisc.edu/22568))使用U-Pb地质年代学。地球的年龄是4.54±0.05 Ga。这个新的结果表明花岗质和长英质的岩浆已经出现在地球~ 1.6亿年后地球之后才形成的。一些其他有趣的日期是4.4到4.45之间的月球形成遗传算法,基于氙同位素的分离固体地球的大气层被认为发生在4.45 Ga。在地球形成之后,形成的核心,从而创建一个金属内核和原始地幔。地球开始降温和分化,从而形成地壳。 Different models suggest a range of possibilities such as a quasi-stable quench crust of peridotitic/komatiitic composition (Smith, J.V., 1981) to a very evolved composition approaching tonalite (Harrison,T.A., 2009). The question now is this crust now a plate or rather, similar to the lithosphere as we know it today? The lithosphere is defined as the brittle outer layer of the Earth and plates are segments of the lithosphere and the base of it is called the Mohorovičić discontinuity, which generally defines the contact between the lithosphere and the upper mantle. It is interesting to think about when these features may have formed as the Earth's outer crust is forming. There is an entire GSA Special Paper volume on the subject of ['When Did Plate Tectonics Begin on Planet Earth?'](http://specialpapers.gsapubs.org/content/440.toc). There is a range of evidence suggesting that plate tectonics as we know it today initiated at the latest around ~3 Ga to as late as ~1 Ga (Condie & Kröner, 2008). Below is a table from that paper that outlines indicators of plate tectonics. ![Table from (Condie & Kröner, 2008) that reviews evidence of plate tecotnics.][1] The outer crust of Earth is likely not stationary, but possibly being dragged along the paths of mantle convection. These brittle segments begins colliding into one another and building upwards while other portions are subducted beneath other plate segments. The convecting mantle causes mantle material to be brought up from depth to conditions at lower pressures, which cause the mantle to melt (this is called adiabatic melting). There was a paper just recently published in Nature by [Bercovici and Ricard(2014)](http://www.nature.com/doifinder/10.1038/nature13072) where they try to answer the question as to why we see geological evidence of proto-subduction at 4 Ga with for prominent subduction features appearing around 3 Ga. I suggest reading the abstract on the papers website but they suggest that ... > when sufficient lithospheric damage combines with transiet mantle > flow and migrating proto-subduction, it leads to the accumulation of > weak plate boundaries and eventually to fully formed tectonic plates > driven by subduction alone. - Bercovici and Ricard (2014) **On the composition of the crust...** The most incompatible elements in the mantle (e.g. lithophile elements [K,Na, Nd] and high field strength elements [U,Th]) will go into the liquid melt and move towards the surface of the Earth and either erupt on the surface or be stored in a magma chamber and further fractionate or differentiate to more felsic magma compositions. Through time, all of these processes will generate different pieces of crust formed from different sources and at varying conditions and later become altered due to either chemical or physical metamorphism. Each of the continents we have today are pieced together from the separation and collision of other tectonic plates. For example, Pangaea was formed due to the collision of many different plates, I am not sure if Pangaea was then considered one giant plate, but it then broke apart and separated. > Is it possible for existing plates to split into two distinct plates? The East African Rift is currently a divergent boundary within the African Plate. So the answer is yes. [1]: http://i.stack.imgur.com/Wq120.png

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\ begingroup美元不错的答案。一些建议:HSF-elements和LIL-elements不相容元素。不相容总是相对的东西。地幔LILE和HFSE是不相容的,但相对兼容地壳(非常符合他们形成的矿物,伟晶岩中最明显)。——也:岩石层被定义为弹性性质,而不是组成。地壳不取回- >板块撤去。 \ endgroup美元
- - - - - -tobias47n9e
2014年4月23日18:00
\ begingroup美元 @Spießburger谢谢你的建议。我会尽量充实这些概念。 \ endgroup美元
- - - - - -丹尼尔
2014年4月23日在19:09

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