Glaciovolcanic hydrothermal environments in Iceland and implications for their detection on Mars
Glaciovolcanic hydrothermal environments in Iceland and implications for their detection on Mars
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DOI：
10.1016/j.jvolgeores.2013.02.009
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发表时间：
2013-04-15
影响因子：
2.9
通讯作者：
Joy, K. H.
中科院分区：
文献类型：
--
作者：
Cousins, C. R.;Crawford, I. A.;Joy, K. H.
火山活动一直是火星上的主导过程，同时也是无处不在的全球冰冻圈。因此，这两者之间的相互作用被认为是可能的。陆相冰川火山作用产生了独特的岩性和蚀变地形，以及可以被微生物居住的热液环境。在此，我们提供了一个框架，用于在未来的火星探测中识别此类冰川火山环境的证据，并为未来天体生物学研究中使用的活跃热液环境提供描述性参考。遥感数据与实地观测和样品分析相结合，包括x射线衍射、拉曼光谱、薄片岩石学、扫描电子显微镜、电子色散光谱仪分析和溶解水化学，以表征来自两个玄武岩冰火山作用地区的样品：冰岛的Askja和Kverkfjoll火山。这些火山之间的冰火地形以冰下喷发的裂缝群脊为特征，这些裂缝群脊后来被多次冰川溃决洪水所改变。Kverkfjoll活跃的热液环境包括温泉、缺氧池、冰川融水湖、含硫和含铁喷气孔，所有这些都位于冰封的地热田内。温度范围为0°C-94.4°C，水环境为酸中性（pH值2-7.5）和硫酸盐为主。玄武岩中的沉积物、矿物结壳和次生矿床的矿物学表明存在两种类型的热液蚀变：一种低温（120℃）组合，以沸石（heulandite）和石英为标志。这些矿物组合与在火星表面发现的一致。代表火星探测器多光谱成像的原位和实验室VNIR （440-1000 nm）反射光谱显示，沉积物的光谱剖面受到含Fe2+/3+矿物的影响，无论它们的主要矿物学特征如何。描述这些陆生冰川火山沉积物的特征可以帮助识别火星上类似的过程，以及识别可能曾经支持和保存生命的古环境。爱思唯尔B.V.版权所有
Volcanism has been a dominant process on Mars, along with a pervasive global cryosphere. Therefore, the interaction between these two is considered likely. Terrestrial glaciovolcanism produces distinctive lithologies and alteration terrains, as well as hydrothermal environments that can be inhabited by microorganisms. Here, we provide a framework for identifying evidence of such glaciovolcanic environments during future Mars exploration, and provide a descriptive reference for active hydrothermal environments to be utilised for future astrobiological studies. Remote sensing data were combined with field observations and sample analysis that included X-ray diffraction, Raman spectroscopy, thin section petrography, scanning electron microscopy, electron dispersive spectrometer analysis, and dissolved water chemistry to characterise samples from two areas of basaltic glaciovolcanism: Askja and Kverkfjoll volcanoes in Iceland. The glaciovolcanic terrain between these volcanoes is characterised by subglacially-erupted fissure swarm ridges, which have since been modified by multiple glacial outburst floods. Active hydrothermal environments at Kverkfjoll include hot springs, anoxic pools, glacial meltwater lakes, and sulphur- and iron-depositing fumaroles, all situated within ice-bound geothermal fields. Temperatures range from 0 degrees C-94.4 degrees C, and aqueous environments are acidic-neutral (pH 2-7.5) and sulphate-dominated. Mineralogy of sediments, mineral crusts, and secondary deposits within basalts suggest two types of hydrothermal alteration: a low-temperature (120 degrees C) assemblage signified by zeolite (heulandite) and quartz. These mineral assemblages are consistent with those identified at the Martian surface. In-situ and laboratory VNIR (440-1000 nm) reflectance spectra representative of Mars rover multispectral imaging show sediment spectral profiles to be influenced by Fe2+/3+-bearing minerals, regardless of their dominant bulk mineralogy. Characterising these terrestrial glaciovolcanic deposits can help identify similar processes on Mars, as well as identifying palaeoenvironments that may once have supported and preserved life. Crown Copyright (C) 2013 Published by Elsevier B.V. All rights reserved.