Multiple stages of aqueous alteration along fractures in mudstone and sandstone strata in Gale Crater, Mars
Multiple stages of aqueous alteration along fractures in mudstone and sandstone strata in Gale Crater, Mars
复制标题
火星盖尔陨石坑泥岩和砂岩地层沿裂缝的多期水蚀变
DOI：
10.1016/j.epsl.2017.04.033
复制
发表时间：
2017
影响因子：
5.3
通讯作者：
L. Thompson
中科院分区：
文献类型：
--
作者：
A. Yen;D. Ming;D. Vaniman;R. Gellert;D. Blake;R. Morris;S. Morrison;T. Bristow;S. Chipera;K. Edgett;A. Treiman;B. Clark;R. Downs;J. Farmer;J. Grotzinger;E. Rampe;M. Schmidt;B. Sutter;L. Thompson
盖尔陨石坑的火星漫游者好奇号首次对父母(未改变)和女儿(改变)关系明确的样本进行了直接的化学和矿物学比较。利用化学矿物学(CheMin)X射线衍射仪和α粒子X射线能谱仪(APXS)分别对砂岩建造蚀变晕内和蚀变晕附近的样品进行了矿物学和化学分析。Stimson组砂岩不整合地覆盖在Murray泥岩建造之上，是Curiosity迄今勘探的最年轻的地层单位。母砂岩的水蚀变导致原始结晶矿物相损失一半，X射线非晶态物质增加三倍。水相流体广泛地浸出母质中的镁、铝、锰、铁、镍、锌等元素，使辉石与长石的比例降低一倍，并引入钙和混合阳离子硫酸盐，被动和主动地富集了二氧化硅含量。在下伏泥岩蚀变晕中还观察到了镁、铝、锰、铁、镍、锌的淋溶和硅、S的富集化。这些观察结果与地下流体的渗透是一致的，这些流体最初是酸性的，然后是碱性的，沿着横切Stimson砂岩和Murray泥岩的裂缝传播。地球化学和矿物学显示了复杂的成岩历史，在不同的环境条件下(如低pH值和中等pH值)有多期水蚀变。这些蚀变晕的形成晚于砂岩和泥岩的岩化作用，是目前已知在盖尔陨石坑发生的最年轻的水文地质事件之一。
The Mars roverCuriosityin Gale crater conducted the first-ever direct chemical and mineralogical comparisons of samples that have clear parent (unaltered) and daughter (altered) relationships. The mineralogy and chemistry of samples within and adjacent to alteration halos in a sandstone formation were established by the Chemistry and Mineralogy (CheMin) X-ray diffraction (XRD) instrument and the Alpha Particle X-ray Spectrometer (APXS), respectively. The Stimson formation sandstones unconformably overlie the Murray mudstone formation and represent the youngest stratigraphic unit explored byCuriosityto date. Aqueous alteration of the parent sandstone resulted in a loss of half of the original crystalline mineral phases and a three-fold increase in X-ray amorphous material. Aqueous fluids extensively leached Mg, Al, Mn, Fe, Ni, Zn and other elements from the parent material, decreased the pyroxene to feldspar ratio by a factor of two, introduced Ca and mixed-cation sulfates, and both passively and actively enriched the silica content. Leaching of Mg, Al, Mn, Fe, Ni and Zn and enrichment of Si and S are also observed in alteration halos in the underlying mudstone. These observations are consistent with infiltration of subsurface fluids, initially acidic and then alkaline, propagating along fractures crosscutting the Stimson sandstone and Murray mudstone. The geochemistry and mineralogy suggest a complicated diagenetic history with multiple stages of aqueous alteration under a variety of environmental conditions (e.g. both low and moderate pH). The formation of these alteration halos post-dates lithification of the sandstones and mudstones and represents one of the youngest hydrogeologic events presently known to have occurred in Gale crater.
影响因子：
56.9
作者：
Blake, D. F.;Morris, R. V.;Sarrazin, P.
通讯作者：
Sarrazin, P.