Concentration of H, Si, Cl, K, Fe, and Th in the low- and mid-latitude regions of Mars
Concentration of H, Si, Cl, K, Fe, and Th in the low- and mid-latitude regions of Mars
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DOI：
10.1029/2007je002887
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发表时间：
2007-12-21
影响因子：
4.8
通讯作者：
Hamara, D. K.
中科院分区：
文献类型：
--
作者：
Boynton, W. V.;Taylor, G. J.;Hamara, D. K.
我们报告地图的浓度的H，Si，Cl，K，Fe和Th确定的伽马射线光谱仪（GRS）在船上的2001年火星奥德赛使命+/-类似于45度纬度。详细描述了光谱处理以产生定量浓度的程序。在不同的火星登陆器位置上测定的元素浓度一般与登陆器的值一致，但Fe除外，尽管GRS Fe数据的平均值与火星陨石的平均值一致。水当量的氢质量浓度从1.5%到7.5%不等，最富集的地区是Apollinaris Patera和Arabia Terra附近。Cl显示出类似于H的分布在表面上，除了在美杜莎槽的Cl含量是远远大于其他地方。铁的分布图显示北方低地相对于南方高地富集。硅在地球表面的质量分数只有19%到22%，但在塔尔西斯山脉和奥林匹斯山以西的地区，硅含量低至18%，硅的消耗量很大。K和Th显示出非常相似的模式，与年轻的火山沉积物和富集与TES表面类型2材料相关的亏损。值得注意的是，似乎没有证据表明全球范围内存在大量成分均匀的厚厚灰尘沉积物。
We report maps of the concentrations of H, Si, Cl, K, Fe, and Th as determined by the Gamma Ray Spectrometer (GRS) on board the 2001 Mars Odyssey Mission for +/-similar to 45 degrees latitudes. The procedures by which the spectra are processed to yield quantitative concentrations are described in detail. The concentrations of elements determined over the locations of the various Mars landers generally agree well with the lander values except for Fe, although the mean of the GRS Fe data agrees well with that of Martian meteorites. The water-equivalent concentration of hydrogen by mass varies from about 1.5% to 7.5% (by mass) with the most enriched areas being near Apollinaris Patera and Arabia Terra. Cl shows a distribution similar to H over the surface except that the Cl content over Medusae Fossae is much greater than elsewhere. The map of Fe shows enrichment in the northern lowlands versus the southern highlands. Silicon shows only very modest variation over the surface with mass fractions ranging from 19% to 22% over most of the planet, though a significant depletion in Si is noted in a region west of Tharsis Montes and Olympus Mons where the Si content is as low as 18%. K and Th show a very similar pattern with depletions associated with young volcanic deposits and enrichments associated with the TES Surface Type-2 material. It is noted that there appears to be no evidence of significant globally distributed thick dust deposits of uniform composition.