MAGMATIC VOLATILES IN PRIMITIVE LUNAR GLASSES .1. FTIR AND EPMA ANALYSES OF APOLLO 15 GREEN AND YELLOW GLASSES AND REVISION OF THE VOLATILE-ASSISTED FIRE-FOUNTAIN THEORY
MAGMATIC VOLATILES IN PRIMITIVE LUNAR GLASSES .1. FTIR AND EPMA ANALYSES OF APOLLO 15 GREEN AND YELLOW GLASSES AND REVISION OF THE VOLATILE-ASSISTED FIRE-FOUNTAIN THEORY
复制标题
DOI：
10.1016/0016-7037(94)00377-x
复制
发表时间：
1995-01-01
影响因子：
5
通讯作者：
RUTHERFORD, MJ
中科院分区：
文献类型：
--
作者：
FOGEL, RA;RUTHERFORD, MJ
通过FTIR和EPMA检查了阿波罗15号绿色和黄色玻璃中溶解的C、S和Cl。 绿色玻璃、火山产生的黄色玻璃和撞击产生的黄色玻璃均未显示出FTIR活性溶解C物质的任何迹象，低至FTIR可检测性（几乎等于50-100 ppm）。 玻璃羟基含量也低于FTIR可检测性（几乎等于10-50 ppm）。 硫和氯含量接近或低于电子探针检测（S = 100-350 ppm，Cl =检测到几乎等于100 ppm）。热化学模拟表明，只有在相对氧化的条件下，C的溶解度才高于FTIR检测限。 如果月球地幔的氧逸度小于0.5个对数单位低于IW，C从苦橄质熔体出溶是不是一个有效的驱动月球火山碎屑喷发的过程。 几乎所有目前对月球地幔f（o2）的估计都指向月球地幔比IW低0.5个对数单位。 这是一致的，缺乏溶解的FTIR可检测的C在本study.Calculations的挥发性损失从月球熔融球在喷发过程中，由于扩散，然后蒸发，表明，大量的C和其他挥发性物质从熔体中丢失。 这是阿波罗15号玻璃中缺乏溶解挥发物的另一种解释。 扩散性挥发损失是伴随月海火山活动产生火山气体的一种有效方式，这一点从月球苦橄质玻璃球上的挥发性涂层中得到了暗示。石墨的氧化和熔体的破碎是挥发物助火喷泉理论的基本原理。 这一过程仍然是对月球火喷泉最合理的解释;然而，我们的研究结论表明，熔融物中的碳出溶在推动火山爆发方面只起了很小的作用。 单独的石墨氧化能够产生所需的火山碎屑效应。 石墨的氧化可通过还原Cr2 O3、TiO 2和FeO进行。 上述组分中的每一种单独具有通过C还原产生令人印象深刻的量的CO气体的能力。 这是由于元素C的还原能力大。
Apollo 15 green and yellow glasses have been examined by FTIR and EPMA for dissolved C, S, and Cl. Neither the green glass, the volcanically produced yellow glass, nor the impact produced yellow glasses show any signs of FTIR active dissolved C species down to FTIR detectability (almost-equal-to 50-100 ppm). Glass hydroxyl contents are also below FTIR detectability (almost-equal-to 10-50 ppm). Sulfur and Cl contents are close to or below electron probe detection (S = 100-350 ppm, Cl = detection to almost-equal-to 100 ppm).Thermochemical modeling demonstrates that C solubility is above FTIR detection limits only under relatively oxidizing conditions. If the lunar mantle is at an oxygen fugacity of less than 0.5 log units below IW, C exsolution from picritic melts is not an effective process for driving lunar pyroclastic eruptions. Almost all the current estimates of lunar mantle f(o2) point to a lunar mantle more reducing than 0.5 log units below IW. This is consistent with the lack of dissolved FTIR detectable C observed in this study.Calculations of volatile losses from lunar melt spheres during eruption, due to diffusion followed by evaporation, suggest that significant amounts of C and other volatiles are lost from the melt. This is an alternative explanation for the lack of dissolved volatiles in the Apollo 15 glasses. Diffusive volatile loss is an effective means of generating the fumarolic gasses that accompanied mare volcanism and is implied by the volatile coatings on lunar picritic glass spheres.The oxidation of graphite and the fragmentation of the melt are the essential tenets of the volatile assisted fire-fountain theory. This process is still the most plausible explanation for lunar fire-fountaining; however, the conclusions of our study suggest that carbon exsolution from the melt played only a minor role in driving the eruptions. Graphite oxidation alone is capable of producing the desired pyroclastic effect. The oxidation of graphite can proceed via the reduction of Cr2O3, TiO2, and FeO. Each one of the above components alone has the capacity to produce impressive amounts of CO gas from reduction by C. This is a result of the large reduction capacity of elemental C.