科学小论文350字左右四年级( 二 )

天文学Astronomy

Aqueously altered igneous rocks sampled on the floor of Jezero crater, Mars
火星杰泽罗陨石坑的水蚀火成岩样本
▲ 作者：K. A. FARLEY, K. M. STACK, D. L. SHUSTER et al.
▲ 链接：
https://www.science.org/doi/10.1126/science.abo2196
▲ 摘要：
“毅力”号火星车在火星杰泽罗陨石坑着陆，调查古代湖泊和河流沉积物。我们报告了对陨石坑底部的观察，在陨石坑的沉积层下面，发现底部由被水改变的火成岩组成。含量最少的成分，非正式命名为Séítah ，是一种粗糙结晶的富含橄榄石的岩石，它积累在岩浆体的底部。
【科学小论文350字左右四年级】沿晶界的镁铁碳酸盐表明在缺水条件下与富含二氧化碳的水发生反应。Séítah之上是一种名为Máaz的成分，我们将其解释为熔岩流或层状火成岩体中Séítah的化学补充物。
这些岩石中的空洞含有硫酸盐和高氯酸盐，很可能是后来近地表卤水蒸发引入的。这些岩石的岩心样本已经被储存在“毅力号”上，以便有可能返回地球。
▲ Abstract：
The Perseverance rover landed in Jezero crater, Mars, to investigate ancient lake and river deposits. We report observations of the crater floor, below the crater’s sedimentary delta, finding that the floor consists of igneous rocks altered by water. The lowest exposed unit, informally named Séítah, is a coarsely crystalline olivine-rich rock, which accumulated at the base of a magma body. Magnesium-iron carbonates along grain boundaries indicate reactions with carbon dioxide–rich water under water-poor conditions. Overlying Séítah is a unit informally named Máaz, which we interpret as lava flows or the chemical complement to Séítah in a layered igneous body. Voids in these rocks contain sulfates and perchlorates, likely introduced by later near-surface brine evaporation. Core samples of these rocks have been stored aboard Perseverance for potential return to Earth.

An olivine cumulate outcrop on the floor of Jezero crater, Mars
火星杰泽罗陨石坑底部的橄榄石堆积露头
▲ 作者：Y. LIU, M. M. TICE, M. E. SCHMIDT et al.
▲ 链接：
https://www.science.org/doi/10.1126/science.abo2756
▲ 摘要：
火星杰泽罗陨石坑底部的地质单元是一个延伸到陨石坑外更广泛的、富含橄榄石的区域地层的一部分。我们研究了杰泽罗底部的Séítah复合物中橄榄石和碳酸盐的岩石学情况。利用“毅力”号获得的多光谱图像和x射线荧光数据，我们对该单元内的Bastide和Brac露头进行了岩石学分析。
我们发现这些露头是由被水流体适度改变的火成岩组成的。火成岩主要由粗粒橄榄石构成，类似于一些火星陨石。我们认为它们是由厚岩浆体经过多级冷却而沉淀和富集橄榄石形成的橄榄石堆积岩。
▲ Abstract：
The geological units on the floor of Jezero crater, Mars, are part of a wider regional stratigraphy of olivine-rich rocks, which extends well beyond the crater. We investigated the petrology of olivine and carbonate-bearing rocks of the Séítah formation in the floor of Jezero. Using multispectral images and x-ray fluorescence data, acquired by the Perseverance rover, we performed a petrographic analysis of the Bastide and Brac outcrops within this unit. We found that these outcrops are composed of igneous rock, moderately altered by aqueous fluid. The igneous rocks are mainly made of coarse-grained olivine, similar to some martian meteorites. We interpret them as an olivine cumulate, formed by settling and enrichment of olivine through multistage cooling of a thick magma body.

地球科学Earth Science

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