Trace element geochemistry of Martian iddingsite in the Lafayette meteorite
Trace element geochemistry of Martian iddingsite in the Lafayette meteorite
复制标题
拉斐特陨石中火星 Iddingsite 的微量元素地球化学
DOI：
10.1029/96je03884
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发表时间：
1997
影响因子：
--
通讯作者：
D. Lindstrom
中科院分区：
文献类型：
--
作者：
A. Treiman;D. Lindstrom
拉斐特陨石含有丰富的边缘，是蒙脱石粘土、水合铁和离子盐矿物的细粒共生体。陨石和陨石坑都在火星上形成。采用仪器中子活化法提取了拉斐特石矿中的硅石、橄榄石和辉石，并对其微量元素进行了分析。我们的结果可与电子和离子微束方法的独立分析相媲美。大多数元素在边缘位置的丰度没有显著的协变。周边地区的汞含量非常丰富，很可能是陆地污染。对于Si， AI, Fe, Mn, Ni， Co和Zn元素，定位位置的组成接近于50%拉斐特橄榄石+ -40%拉斐特硅玻璃+ -10%水的混合物。这些元素之间的一致行为与蒙脱石和水之间的元素分异不相容，但含水性质和边缘位置的岩石环境清楚地表明水源。这些推论都是一致的，然而，与沉积的ididsite最初作为一个硅酸盐凝胶，然后结晶（新形成）几乎等化学。边缘位置的镁含量明显高于模型所暗示的，这可能表明改变溶液富含Mg 2÷。
The Lafayette meteorite contains abundant iddingsite, a fine-grained intergrowth of smectite clay, ferrihydrite, and ionic salt minerals. Both the meteorite and iddingsite formed on Mars. Samples of iddingsite, olivine, and augite pyroxene were extracted from Lafayette and analyzed for trace elements by instrumental neutron activation. Our results are comparable to independent analyses by electron and ion microbeam methods. Abundances of most elements in the iddingsite do not covary significantly. The iddingsite is extremely rich in Hg, which is probably terrestrial contamination. For the elements Si, AI, Fe, Mn, Ni, Co, and Zn, the composition of the iddingsite is close to a mixture of-50% Lafayette olivine + -40% Lafayette siliceous glass + -10% water. Concordant behavior among these elements is not compatible with element fractionations between smectite and water, but the hydrous nature and petrographic setting of the iddingsite clearly suggest an aqueous origin. These inferences are both consistent, however, with deposition of the iddingsite originally as a silicate gel, which then crystallized (neoformed) nearly isochemically. The iddingsite contains significantly more magnesium than implied by the model, which may suggest that the altering solutions were rich in Mg 2÷.