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土壤和河流沉积物吸附三价铬过程中的铬同位素分馏
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作者 方子遥 何小庆 +1 位作者 俞樨 秦礼萍 《中国科学技术大学学报》 CAS CSCD 北大核心 2023年第5期13-21,I0002,I0008,共11页
沉积岩的铬同位素组成已被广泛应用于重建地质历史时期大气氧气含量的波动。这一指标的一个基本前提是自然环境中铬同位素分馏只发生在六价铬与三价铬的氧化还原转化过程中。但是,对非氧化还原过程中的铬同位素分馏行为目前仍然不清楚... 沉积岩的铬同位素组成已被广泛应用于重建地质历史时期大气氧气含量的波动。这一指标的一个基本前提是自然环境中铬同位素分馏只发生在六价铬与三价铬的氧化还原转化过程中。但是,对非氧化还原过程中的铬同位素分馏行为目前仍然不清楚。本文通过模拟实验发现三价铬被土壤和河流沉积物吸附这一非氧化还原过程也会造成明显的铬同位素分馏。这一过程的铬同位素分馏系数(-0.06‰至-0.95‰,表示为103lnα)要小于氧化还原过程中的。结合前人对于有机配体溶解三价铬过程伴随的非氧化还原铬同位素分馏的研究结果,本文认为沉积岩中观测到的系统性的非常偏正的铬同位素记录可以被解释为大气氧化事件,但是在某些地质时代观测到的较弱的偏正铬同位素记录可能是由于非氧化还原过程造成的,应谨慎解译数据。 展开更多
关键词 铬同位素 吸附 非氧化还原铬循环 大气氧含量
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Constraints on water activity at the Zhurong landing site in Utopia Planitia,Mars 被引量:1
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作者 ChengZheng Yong ziyao fang +2 位作者 CongCong Zhang JunFeng Zhen LiPing Qin 《Earth and Planetary Physics》 EI CSCD 2023年第3期356-370,共15页
Mineralogical evidence of water–rock interactions is a strong indicator of the presence of liquid water on ancient Mars.Previous observations have found widely distributed hydrated minerals in the southern highlands,... Mineralogical evidence of water–rock interactions is a strong indicator of the presence of liquid water on ancient Mars.Previous observations have found widely distributed hydrated minerals in the southern highlands,whereas such discoveries have been rare in the younger northern lowlands.China’s first Mars exploration mission successfully landed a rover(Zhurong)in southern Utopia Planitia,providing an opportunity to analyze the exposed rocks in the northern lowlands.Using data from the short-wave infrared(SWIR)spectrometer and the laser-induced breakdown spectrometer(LIBS)onboard the Zhurong rover,we found evidence for the widespread presence of hydrated minerals(probably sulfates or silica)around the landing site.The basaltic-like elemental compositions of the targeted samples further indicated that hydrated minerals are likely minor components.The results from Zhurong suggest that active aqueous activities occurred during the overall cold and dry Amazonian era on Mars.However,further evaluations are needed on the duration and scale of these activities. 展开更多
关键词 Zhurong rover hydrated mineral water activity Amazonian
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