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首页> 外文期刊>Earth and Planetary Science Letters: A Letter Journal Devoted to the Development in Time of the Earth and Planetary System >Temperatures on Mars from ~(40)Ar/~(39)Ar thermochronology of ALH84001
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Temperatures on Mars from ~(40)Ar/~(39)Ar thermochronology of ALH84001

机译：ALH84001的〜（40）Ar /〜（39）Ar热年代中的火星温度

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摘要

The thermal history of Martian meteorite ALH84001 has critical implications for its petrological and deformational history, the age of its trapped atmospheric gases, the timing of the Martian dynamo, and possibly the evolution of Martian surface temperatures during the last 4 billion years (Gyr). Feldspathic glass in ALH84001 has been dated using ~(40)K/~(40)Ar and ~(40)Ar/~(39)Ar chronometry by several laboratories. There is general agreement that these chronometers were last reset sometime between 3.9 and 4.3 billion years ago (Ga). Using the ~(40)Ar/~(39)Ar data from Bogard and Garrison [Meteorit. Planet. Sci. 34 (1999) 451-473] to model several limiting thermal histories of the meteorite, here we show that most of ALH84001 feldspathic glass has probably not been heated to more than ～350-meteorite, here we show that most of ALH84001 feldspathic glass has probably not been heated to more than ～350-500℃ and shocked to peak pressures ～ > 1 GPa since the glass was last melted. This indicates that most of ALH84001 has been well below these temperatures since 3.9-4.3 Ga. Since these temperatures are below the Curie point of magnetite, much of the magnetization recently identified in ALH84001 carbonate [Weiss et al., Earth Planet. Sci. Lett. this issue] must have been acquired by ～ 4 Ga. This also provides an explanation for why ALH84001 contains a sample of an apparently ancient Martian atmosphere that is less evolved to that on present-day Mars. Our calculations also suggest that for the last 4 Gyr, average surface temperatures on Mars may not have been much higher than the present cold conditions.～
机译：火星陨石ALH84001的热史对其岩石学和变形史，被困大气的年龄，火星发电机的时间安排以及最近40亿年（吉尔）中火星表面温度的演变具有至关重要的意义。几个实验室已使用〜（40）K /〜（40）Ar和〜（40）Ar /〜（39）Ar测年仪对ALH84001中的长视玻璃进行了测年。人们普遍同意，这些天文钟的上一次重置时间为3.9至43亿年前（Ga）。使用Bogard和Garrison的〜（40）Ar /〜（39）Ar数据[Meteorit。行星。科学34（1999）451-473]模拟了陨石的几个极限热历史，这里我们显示大多数ALH84001长石玻璃可能没有加热到〜350陨石，这里我们表明大多数ALH84001长石玻璃具有自上次玻璃熔化以来，温度可能未加热到〜350-500℃以上并达到峰值压力≥> 1 GPa。这表明自3.9-4.3 Ga以来，大多数ALH84001都远低于这些温度。由于这些温度低于磁铁矿的居里点，因此，最近在ALH84001碳酸盐中发现了许多磁化强度[Weiss等人，Earth Planet。科学来吧这个问题]必须是在约4 Ga下获得的。这也解释了为什么ALH84001包含了一个看起来很古老的火星大气样本，而该样本却没有演化到如今的火星。我们的计算还表明，对于最近的4 Gyr，火星的平均地表温度可能不会比当前的寒冷条件高很多。

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