为什么地壳比镁铝,太阳比铝镁吗?- 江南体育网页版- - - - -地球科学堆江南电子竞技平台栈交换 最近30从www.hoelymoley.com 2023 - 07 - 10 - t13:09:18z //www.hoelymoley.com/feeds/question/19789 https://creativecommons.org/licenses/by-sa/4.0/rdf //www.hoelymoley.com/q/19789 1 为什么地壳比镁铝,太阳比铝镁吗? URIZEN //www.hoelymoley.com/users/18551 2020 - 06 - 01 - t02:51:56z 2020 - 06 - 04 - t05:56:02z < p >镁代表0.07%的太阳的光球层的成分而铝占0.006%。因此,有更多比铝镁在太阳的光球。< / p > < p >但同样并不发生在地壳,其中镁表示2.9%的成分和铝占8.1%。< / p > < p >有特别的原因是如此吗? < / p > //www.hoelymoley.com/questions/19789/-/19791 # 19791 4 地壳由Gimelist回答为什么比镁铝,太阳比铝镁吗? Gimelist //www.hoelymoley.com/users/725 2020 - 06 - 01 - t11:20:29z 2020 - 06 - 02 - t00:26:38z < p >地球作为一个整体,有更多比铝镁。< / p > < p >你的问题是为什么,特别是在地壳,还有更多比镁铝。< / p > < p >原因是毫克是< em > < / em >元素兼容而艾尔是一个< em > < / em >不相容元素。There were several questions here that addressed some aspects of this topic, for example:

What are the high field strength and large ion lithophile (HFS or HFSE & LIL or LILE) elements?

What was the likely composition of Earth's early crust (how did crustal composition evolve)?

Why silicon is abundant in earth surface?

Why do felsic materials have lower melting points than mafic?


Why is there more Al than Mg in the crust?

In earth's (upper) mantle, most Mg is inside the mineral olivine, with some in other minerals such as clinopyroxene and orthopyroxene. In contrast, most Al is in the minerals plagioclase, spinel, and garnet. There could be a tiny amount of Al in the pyroxenes as well.

When you melt the solid mantle rock that is composed of all of the minerals I listed above, some minerals melt at lower temperatures than the others. So the magma composition that is formed more closely resembles those minerals that melted.

As you can guess, the Mg-rich minerals are refractory (that is, they are harder to melt). The Al-rich minerals are usually very easy to melt. So whenever you have magma that comes from the mantle into the crust, it will have more Al than Mg. Over the billions of years of Earth's crustal evolution, quite a lot of Al (along with Na, K, Fe, Ca, and Si) accumulated in the crust, relative to the amount that was in the parental mantle.

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