什么是地球早期的可能组成地壳(地壳成分是如何进化)?- 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 - 26 - t19:48:34z //www.hoelymoley.com/feeds/question/6893 https://creativecommons.org/licenses/by-sa/4.0/rdf //www.hoelymoley.com/q/6893 6 什么是地球早期的可能组成地壳(地壳成分是如何进化)? Inkenbrandt //www.hoelymoley.com/users/510 2015 - 11 - 10 - t07:09:42z 2015 - 11 - 11 - t03:10:35z < p >是第一个完全地壳镁铁质(海洋)地壳后来蒸馏通过火山弧俯冲带,使长英质的岩石或地球开始少量长英质的壳吗?< / p > < p >是古老的锆石最有可能从长英质的或镁铁质岩石? < / p > //www.hoelymoley.com/questions/6893/-/6898 # 6898 2 回答由戈登斯坦格对地球早期的可能组成地壳(地壳成分是如何进化)? 戈登斯坦格 //www.hoelymoley.com/users/4507 2015 - 11 - 10 - t19:52:05z 2015 - 11 - 10 - t19:52:05z < p >除了相对薄单板的沉积物,今天的地壳物质主要是花岗岩在自然界中,熔化温度约850度C。我们不知道早期proto-Earth成分,但进一步与假定的忒伊亚的碰撞(见< a href = " https://en.wikipedia.org/wiki/Giant_impact_hypothesis " rel =“nofollow”> https://en.wikipedia.org/wiki/Giant_impact_hypothesis < / >)的结合热能原始引力吸积和动能的碰撞,将会提高了温度超过2000摄氏度的超镁铁的熔点。的pre-fractionated precurser的地壳和地幔是碱性,与水、K, Na等所有压抑的冰点。不过第一个分离的地壳会被温度远高于850摄氏度,因此有可能几个周期的分馏,俯冲和重熔越来越酸性(对二氧化硅)地壳辨认“唾液”之前地壳稳定。< / p > < p >可以因此认为,纯粹的基于温度,第一个地壳一定是镁铁质(玻古安山岩火山岩?),甚至倾向于超基性的,而且由于锆质耐火材料,希望第一个锆石有镁铁质协会,与后来的花岗岩协会。< / p > //www.hoelymoley.com/questions/6893/-/6900 # 6900 3 Gimelist回答的是什么可能构成地球早期地壳(地壳成分是如何进化)? Gimelist //www.hoelymoley.com/users/725 2015 - 11 - 11 - t03:10:08z 2015 - 11 - 11 - t03:10:08z < p >戈登的回答是正确的一阶近似。< / p >

However, the zircons that were found in Jack Hills are from the Hadean, more than 4 billion years ago. The fact that zircons that old exist is interesting - zircon is not a mineral you find in mafic rocks. Zirconium is an incompatible element in the mantle, so to get enough of it to form its own mineral you need some partial melting events. This may also be of interest:

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

When you melt the mantle, you end up having basalt or more felsic rocks. If you have enough zircon in mafic rocks, you form baddeleyite: ZrO2. Zircon, ZrSiO4 will only form in more felsic rocks, where you have enough Si. This alone suggests that some parts of the early crust was somewhat more felsic than a basalt.

There's more to it: inclusions of quartz and oxygen isotope data indicate that not only the zircon was in a felsic rock, it has evidence to suggest liquid water and hydrothermal alteration.

This entire thing is heavily debated, because there's only so much you can tell from a few grains of zircon. However, the basics are there - some felsic rocks existed as far as the Hadean.

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