< p >硅、二氧化硅的形式(氧化硅:Si <一口> 4 + < /一口>或SiO <子> 2 < /订阅>),确实是很常见的在地球表面。< / p > < p >这个答案有两个部分:为什么硅常见的地球作为一个整体,以及为什么它是特别集中在地壳表面(因此)。< / p > < p > < >强为什么硅地球常见的< /强> < / p > < p >硅形式在大型恒星核合成过程(比我们的太阳)和超新星。发现相当多的硅可以这种方式形成的。当太阳系还热分子气体云,我们地区地方丰富的硅(在其他元素)最终地球上有大量的硅。这是我专业领域之外的,所以我将参考链接丹尼尔。诺依曼给他的评论和< a href = " http://scienceline.ucsb.edu/getkey.php?关键= 24 nofollow noreferrer“rel = >这好的解释UCSB科学行< / >。< / p > < p > < >强为什么在地壳硅极富吗?< /强> < / p > < p >现在我们知道地球有相当多的硅。你如何得到更多的地壳(最外层)的硅比地幔(之间的中间层,地壳和铁金属芯)?< / p > < p >答案在于岩石融化时发生了什么。你有岩石地幔,比方说35%到45%的SiO 2 <子> < /订阅>。 When this rock gets heated or decompressed (or wet, but nevermind this for now), it melts. But it doesn't melt completely, it melts only partially. This will always be richer in SiO2 than the original rock, and the residue of the melting now has even less SiO2. Once SiO2-rich melt moves upwards in the Earth (sometimes even erupting as volcanoes), it moves more SiO2-rich material to the crust. Over billions of year and large successive partial melting events, you end up having quite a lot of SiO2 in the crust. This gets even better, because in those SiO2-rich rocks, you also have lots of quartz - which is a mineral composed of pure SiO2: 100% SiO2. This is a very resistant mineral to alteration and weathering. So if you have a granite that has only a third of quartz, with time the other two thirds (mostly feldspars) will decay and turn into clays (aka dust, mud). Only the quartz will be left behind, and the rest will wash away with water to the oceans (eventually). This is why you have impressive sand dunes which are "seas" of almost pure SiO2:
Some other questions on this website you might be interested in:
What was the likely composition of Earth's early crust (how did crustal composition evolve)?
Why do felsic materials have lower melting points than mafic?