Olivine from planetary basalts: Chemical signatures that indicate planetary parentage and those that record igneous setting and process
Olivine from planetary basalts: Chemical signatures that indicate planetary parentage and those that record igneous setting and process
复制标题
来自行星玄武岩的橄榄石：表明行星起源以及记录火成岩环境和过程的化学特征
DOI：
10.2138/am-2003-5-609
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发表时间：
2003
影响因子：
3.1
通讯作者：
C. Shearer
中科院分区：
文献类型：
--
作者：
J. Karner;J. Papike;C. Shearer
用电子和离子探针技术研究了来自地球、月球和火星的13个玄武岩套中橄榄石中的锰、铁、镍、钴、钛、铬、钒的系统学特征。结果表明，橄榄石的化学特征可能与：(1)行星的亲缘关系，其中差异是初始吸积比、源成分和氧逸度的结果；以及(2)火成岩环境和过程，其中行星内玄武岩套的差异是构造环境中特定的氧化还原条件、不同的熔体组成以及结晶序列和矿物模式导致的元素分配变化的结果。锰-铁系统学表明，橄榄石中的锰/铁比值随着与太阳距离的增加而增加的行星母系(月球除外，这是可以解释的)。这一序列可能是太阳系开始时初始的Mn/Fe吸积比的结果。不同的熔体成分和结晶序列等火成作用导致同一星球玄武岩套中橄榄石的Mn/Fe比值不同。镍-钴和钛系统学表明，行星特征是三颗行星源区差异的结果。例如，与地球和火星相比，月球源区亏损镍而富钛，这些特征在橄榄石成分中得到了反映。镍、钴、钛在行星橄榄岩套中的不同分配行为是玄武岩结晶序列和初始熔体组成的结果。橄榄石中的铬浓度是由三个行星源区不同的氧逸度和相稳定性造成的，而橄榄石中的V浓度主要是行星体内不同的整体氧化还原条件的结果。由于熔体成分、结晶序列和模式矿物学的不同，铬和钒都显示出火成过程的特征。也许这项研究得出的最重要的结论是，行星玄武岩中的橄榄石不仅记录了有关火成环境和过程的信息，还记录了行星的起源，使比较行星矿物学的研究成为获得玄武岩成因新见解的令人兴奋的方式。
Abstract The systematics of Mn-Fe, Ni-Co, Ti, Cr, and V in olivine from 13 basalt suites from the Earth, Moon, and Mars were studied by electron and ion microprobe techniques. The results demonstrate that chemical signatures in olivine can be related to: (1) planetary parentage, where differences are the result of initial accretional ratios, source compositions, and oxygen fugacity; and also (2) igneous setting and process, where differences among basalt suites within a planet are a consequence of specific redox conditions in tectonic settings, differing melt compositions, and changes in element partitioning resulting from crystallization sequences and mineral modes. Manganese-Fe systematics indicate planetary parentage where the Mn/Fe ratio in olivine increases with increasing distance from the Sun (with the exception of the Moon, which can be explained). This sequence could be the result of initial Mn/Fe accretional ratios from the start of the solar system. Igneous processes such as differing melt compositions and crystallization sequences cause differences in the Mn/Fe ratios of olivine in basalt suites from the same planet. Nickel-Co and Ti systematics show that planetary signatures result from source-region differences among the three planets. For example, the lunar source regions are depleted in Ni and enriched in Ti, as compared with the Earth and Mars, and these characteristics are reflected in the olivine compositions. The differing partitioning behavior of Ni, Co, and Ti in planetary olivine suites is a result of crystallization sequences and initial melt compositions of the basalts during crystallization. Chromium concentrations in olivine result from differing oxygen fugacities and phase stabilities in the source regions of the three planets, whereas V concentrations in olivine are mostly a consequence of the different overall redox conditions on planetary bodies. Both Cr and V show igneous process signatures owing to different melt compositions, crystallization sequences, and modal mineralogy. Perhaps the most important conclusion from this study is that olivine in planetary basalts records information not only about igneous setting and process but planetary parentage as well, making the study of comparative planetary mineralogy an exciting way to gain new insights into basalt petrogenesis.