基于辐射传输模型的月表铁镁质矿物定量反演:以嫦娥三号着陆区为例

我国嫦娥三号着陆于雨海北部的年轻玄武岩熔岩平原上,该区域的物质成分和矿物组成对于理解月球年轻的火山活动具有重要研究价值。月球全球勘探者(Lunar Prospector,LP)探测的元素数据揭示着陆区附近岩石类型主要为高铁中钛玄武岩(19.5%FeO;5.2%TiO_2)。本研究利用月球矿物绘图仪(Moon Mineralogy Mapper,M~3)获取的嫦娥三号着陆区附近的新鲜撞击坑高光谱数据,采用Hapke辐射传输模型和修正高斯模型(MGM)联合分析,对其年轻月海玄武岩铁镁质矿物进行了定量反演。研究表明该区域玄武岩中矿物组成以单斜辉石矿物为主,存在较高比例的橄榄石。基于光谱库匹配方法和MGM优化分析,我们反演出单斜辉石,斜方辉石,橄榄石和钛铁矿四种矿物的相对体积比为57.6:18.0:15.3:9.1,这一研究结果有待于与嫦娥三号玉兔号月球车上搭栽的红外成像光谱仪数据进行比对,以期从遥感和就位探测两个角度获得对于该地区矿物和岩石类型的全面认识。     

月球冷海玄武岩矿物成分研究

月海玄武岩的矿物组成反映了岩浆源区的化学成分以及岩石形成时的物理和化学环境,对月球热演化研究以及月球资源的开发利用都具有重要意义。本文选择延展范围长的冷海为研究区,基于月球矿物成像光谱仪(Moon Mineralogy Mapper,简称M3)数据研究其矿物的空间变化特征。综合利用光谱、地形、元素等多源遥感数据将冷海划分为25个地质单元。提取169条新鲜坑光谱曲线,获取吸收中心波长、波段面积比等光谱参数。通过光谱吸收特征分析,获得冷海玄武岩铁镁质矿物变化特征。东部冷海地层较老,铁镁质矿物主要为单斜辉石,辉石钙含量较月球样品单斜辉石钙偏低,与澄海以及雨海老的地层矿物组成类似。西部冷海和露湾的地质单元较为年轻,富含橄榄石。风暴洋和雨海年轻玄武岩的矿物也富含橄榄石。这种富含橄榄石、大面积分布的玄武岩反映了月球晚期热演化的独特性。尽管地理上冷海为一个独立的月海,其东西部玄武岩矿物组成的差异以及与其同位置周围月海矿物组成的类似性反映了冷海玄武岩源区与周围月海具有联系。     

月球反射光谱学及应用

随着我国探月工程稳步开展以及未来深空探测需求,反射光谱学研究在我国重新受到重视。文中简要介绍了月球反射光谱学原理及其研究方法,并以“嫦娥三号”着陆场所在的雨海地区为例展示反射光谱学的部分应用。与背面斜长岩高地相对单调的光谱特征不同,雨海周边高地展示了多样性的吸收特征,岩石类型以苏长岩质岩石为主,橄榄石、辉石、尖晶石等矿物都有分布。月球上最古老的和最年轻的玄武岩在雨海盆地也都有分布。古老的中、低钛玄武岩以易变辉石为主兼有少量低钙普通辉石,年轻的高钛玄武岩富含橄榄石。雨海乃至整个风暴洋地区玄武岩较之其他月海玄武岩贫Ca。雨海地区的元素、矿物组成以及玄武岩时代都具多样性,该区是研究月球热演化的重要地区。     

月球花岗岩--比较行星学意义

与大陆地壳广泛出露的花岗岩不同,在月球表面仅发现了少量细小的花岗岩碎屑,此外有长英质组分以熔体包裹体形式出现于月球玄武岩的矿物中。月球花岗岩碎屑的主要矿物为石英、钾长石和钙质斜长石,具花斑状结构;含少量铁橄榄石、单斜辉石、钛铁矿、锆石、磷灰石、白磷钙矿等矿物,缺少含水矿物。月球花岗岩富K2O,富Ba,相容元素(Cr、Sc、Co、V)含量比其它月岩低,具有平坦或Ⅴ型的REE型式,负Eu异常明显。它们的化学特征可以用硅酸盐液态不混熔来解释。月球花岗岩的结晶年龄在4．4～3．9Ga间,具有至少8个年龄峰,可能代表了与花岗岩形成相关的8次独立的岩浆事件。由于月球花岗岩成因和分布对于认识月球演化和岩浆作用历史至关重要,在新一轮的深空探测中,应更加重视对月球花岗岩的研究。     

蒙阴金伯利岩中橄榄石的含水性研究及其意义

<正>橄榄石是金伯利岩中最为重要的组成矿物之一,也是金刚石的共生矿物之一。金伯利岩中的橄榄石斑晶/捕虏晶的红外光谱图中具有复杂多样的OH吸收峰,这反映了它们的幔源化学组成、最终平衡条件以及来源的差异性。由此看来,这似乎暗示着,利用橄榄石的OH红外光谱特征,可有效用于判断金伯利岩的金刚石含矿性等。作为一种探索性实验,笔者测量了山东蒙阴金伯利岩中的38粒橄榄石样品,旨在寻找金伯利岩中橄榄石的     

顾及太空风化效应的虹湾地区矿物含量反演

月表矿物含量反演是研究月球地质起源和演化的关键.太空风化作用普遍发生在月球表面,对矿物纯净光谱造成了不可忽视的影响,它弱化光谱吸收特征, 降低反射率,影响矿物含量遥感反演精度.基于Relab光谱库和Hapke辐射传输模型,将月表 4种矿物(单斜辉石、斜方辉石、斜长石、橄榄石)的二向性反射率转换成同向性的单次散射反照率,然后计算矿物的光学常数;再根据亚微观金属铁SMFe(submicroscopic metallic iron)的质量分数模拟6种不同程度太空风化效应,得到端元矿物的反射率光谱;最后基于上述方法,利用多端元线性分解方法和M3(moon mineralogy mapper,月球矿物绘图仪)高光谱数据反演不同风化程度下的矿物含量,得到月表虹湾地区辉石、斜长石、橄榄石3种矿物的含量分布.实验表明,利用多端元线性分解可以有效模拟太空风化效应对矿物光谱的影响,是研究太空风化效应影响下矿物识别及含量反演的一种行之有效的方法.      

月球地形地貌对各种月面探测技术的影响

月球的地形地貌一直以来都是备受关注的重要内容,它对光学成像、热红外、微波辐射等遥感探测以及月面探测活动具有重要的影响。与地球不同,月球上没有大气、海洋,也未发现生命迹象,对月球的探测直接面对着高低起伏变化的月球表面。而且,特殊的地形地貌,在矿物组成、含量方面也表现出显著的差异。本文介绍了光学成像、热红外遥感以及微波辐射遥感等月面探测技术的原理,通过分析其主要影响机理,认为月球地形地貌对各种月面探测技术的影响主要体现在不同地貌的岩石类型和组成差异影响、地形起伏和热环境差异影响以及崎岖月面安全威胁三个方面,这也是今后研究的重要发展方向。     

基于ASTER的雅鲁藏布江缝合带泽当-罗布莎蛇绿岩套分析和组分识别

本文通过对西藏雅鲁藏布江缝合带泽当-罗布莎地区蛇绿岩套的主要岩石组成和蚀变矿物的标准波谱吸收特征分析,比较了标准光谱库的相应岩性光谱吸收特征和ASTER数据波段特征之间的关系,采用连续统去除、比值法和光谱角制图法对ASTER影像数据进行处理及相关岩性和矿物提取。结果表明,蛇绿岩组分岩性中亚铁离子和Fe-OH,Mg-OH的可见-短波红外吸收特征显著,而且有一个宽波长范围的Si-O热红外光谱特征,基于这些光谱特征采用ASTER数据和比值法与光谱角制图法可有效地识别蛇绿岩的主要岩性和相关矿物成分及其空间分布,结果与地质资料基本吻合。     

不同亚类硅酸盐矿物的中红外光谱学特征

利用热红外发射光谱研究了不同亚类硅酸盐矿物镁橄榄石、透闪石、蛇纹石和钠长石的红外发射光谱特征。在120oC时,通过对400～1650 cm-1的红外波段进行积分计算,发现硅酸盐矿物中镁橄榄石的发射率最高,可达到0.988,钠长石最低为0.947。硅酸盐矿物在850～1300cm-1区间均产生宽的低发射带,该发射带与硅氧四面体层中(Si,Al)-O的伸缩振动相关;在470 cm-1左右则形成相对尖锐的低发射带,与硅氧四面体层中(Si, Al)-O的弯曲振动相关。从岛状、链状、层状到架状硅酸盐矿物由于Si O2聚合程度依次增加,最强发射谷的位置依次向高频方向偏移,说明硅氧四面体中Si-O伸缩振动带的位置受到了n(Si)/n(O)比值的制约。此外,在辐射能量谱里,镁橄榄石、透闪石、蛇纹石和钠长石的最强辐射谷范围趋于变宽,依次为115、162、225和247 cm-1,反映了吸收的辐射能增加。综上可推测,硅酸盐矿物强的发射率可能与硅氧四面体中Si-O的振动模式、Si O2的聚合度、辐射能量谱中最强辐射谷的波长范围有关。     

基于Hapke辐射传输模型的月壤光谱模拟

由于月球采样点较少,月壤真实数据稀缺,限制了对月球科学问题的进一步研究。较全面系统地采集月壤样品在近期很难完成,开展月壤光谱模拟工作是月壤实测光谱的必要有益补充,可以为研究月壤光谱特征提供大量数据。基于Hapke模型,我们选取RELAB光谱库的斜长石、单斜辉石、斜方辉石、橄榄石、单质铁、钛铁矿、火山玻璃、熔融玻璃等典型月壤矿物,运用牛顿插值和最小二乘优化的方法,模拟了LSCC月壤数据的一定粒径、单质铁含量、观测条件及矿物混合比例下的混合光谱。模拟光谱与实测光谱拟合较好,相关系数均大于0.99,均方根误差在10-3数量级;模拟矿物丰度与实测矿物丰度基本一致;模拟SMFe含量与相对成熟度指数Is/FeO线性关系明显;模拟粒径基本落在实测粒径组范围内。最后,文中讨论了光谱吸收中心波长、吸收面积等光谱特征参数的模拟精度,以及高精度模拟光谱时光学常数的计算方法。     

Correlation analysis and partial least square modeling to quantify typical minerals with Chang＇E-3 visible and near-infrared imaging spectrometer＇s ground validation data

In 2013, Chang＇E-3 program will develop lunar mineral resources in-situ detection. A Visible and Near-infrared Imaging Spectrometer （VNIS） has been selected as one payload of CE-3 lunar rover to achieve this goal. It is critical and urgent to evaluate VNIS＇ spectrum data quality and validate quantification methods for mineral composition before its launch. Ground validation experiment of VNIS was carried out to complete the two goals, by simulating CE-3 lunar rover＇s detection environment on lunar surface in the laboratory. Based on the hyperspectral reflectance data derived, Correlation Analysis and Partial Least Square （CA-PLS） algorithm is applied to predict abundance of four lunar typical minerals （pyroxene, plagioclase, ilmenite and olivine） in their mixture. We firstly selected a set of VNIS＇ spectral parameters which highly correlated with minerals＇ abundance by correlation analysis （CA）, and then stepwise regression method was used to find out spectral parameters which make the largest contri- butions to the mineral contents. At last, functions were derived to link minerals＇ abundance and spectral parameters by partial least square （PLS） algorithm. Not considering the effect of maturity, agglutinate and Fe~, we found that there are wonderful correlations between these four minerals and VNIS＇ spectral parameters, e.g. the abundance of pyroxene correlates positively with the mixture＇s absorption depth, the value of absorption depth added as the in- creasing of pyroxene＇s abundance. But the abundance of plagioclase correlates negatively with the spectral parame- ters of band ratio, the value of band ratio would decrease when the abundance of plagioclase increased. Similar to plagioclase, the abundance of ilmenite and olivine has a negative correlation with the mixture＇s reflectance data, if the abundance of ilmenite or olivine increase, the reflectance values of the mixture will decrease. Through model validation, better estimates of pyroxene, plagioclase and ilmenite＇s abundances are given. It is concluded that VNIS has the capability to be applied on lunar minerals＇ identification, and CA-PLS algorithm has the potential to be used on lunar surface＇s in-situ detection for minerals＇ abundance prediction.     

月球风暴洋火山口暗物质矿物反演及地质意义

月表主要矿物的空间分布是研究月球起源及演化等科学问题的重要信息之一.以风暴洋地区为例, 根据不同矿物光谱在可见光-近红外波段的吸收特征, 使用印度M3(moon mineralogy mapper)数据, 应用波谱特征拟合法(SFF)反演了火山口附近暗物质区域的单斜辉石、斜方辉石、橄榄石和尖晶石等铁镁质矿物的分布, 反演结果显示: 风暴洋地区提取的铁镁质矿物分布较集中, 其中辉石含量较多, 橄榄石和尖晶石含量相对较少.另外着重分析了橄榄石、尖晶石与周围矿物的关系及其地质意义.将提取结果与Lucey用于Clementine影像的光学模型填图结果进行对比显示, 提取的橄榄石分布集中, 但不存在大尺度的分布, 这与本文的研究区域面积有关; 就位置而言, 二者具有较好的一致性.      

Mineral surface modification induced by low energy ion irradiation: Implications for solar-wind exposure effects in lunar soil

We performed ion irradiation on olivine and ilmenite to simulate solar-wind exposure effects in lunar soil. The surface morphology and microstructure after ion irradiation were characterized by field emission scanning electron microscopy. Sputtering erosion significantly modified the surface of irradiated Luobusha olivine grains. All irradiated grains show smooth surface and round shape. The cleavage fractures on the unirradiated olivine surface were widened and deeply etched after He＋ irradiation. Both of these are the consequence of ion sputtering erosion. There are no bubbles or voids foundin the irradiated olivine grains, because He＋ dose in this study is lower than saturated fluence. Irradiated Panzhihua ilmenite grains are all covered with smooth flakes with the thickness of about 400 nm. The formation of the flakes should be related with helium bubbles and their growth during He＋ implantation. Some columnar-shaped particles are found at the surface of irradiated Panzhihua ilmenite. We speculate that these particles should be sulfide because of significantly high sulfur contents.     

The stability and major element partitioning of ilmenite and armalcolite during lunar cumulate mantle overturn

Ilmenite has played an important role in the petrogenesis of lunar high-Ti picritic magmas, and armalcolite is another high-Ti oxide that was first discovered on the moon. In this study, we examined the thermodynamic stability of ilmenite and armalcolite in the context of lunar cumulate mantle overturn. Two starting compositions were explored, an ilmenite-bearing dunite (olivine + ilmenite) and an ilmenite-bearing harzburgite (olivine + orthopyroxene + ilmenite). Experiments were conducted using a 19.05 mm piston-cylinder apparatus at temperatures of 1235-1475 °C and pressures of 1-2 GPa. In runs with the ilmenite-bearing dunite mixture, ilmenite is stable in the subsolidus assemblage at least up to 1450 °C and 2 GPa. In runs with the ilmenite-bearing harzburgite starting mixture, ilmenite is stable at pressures greater than 1.4 GPa, and armalcolite is stable at lower pressures. Solidi for both starting compositions were determined, and the phase boundary between ilmenite- and armalcolite-bearing harzburgite was shown to have little dependence on temperature. During lunar cumulate overturn, sinking ilmenite formed near the end of lunar magma ocean solidification transforms into armalcolite when in contact with harzburgite cumulates at depths of less than 280 km in the lunar mantle. Inefficient overturn could leave isolated, inhomogeneously distributed pockets of armalcolite-bearing harzburgite in the upper lunar mantle, underlain by an ilmenite-bearing lower lunar mantle. These high-Ti oxide-bearing harzburgitic pockets can serve as potential sources for the generation of high-Ti magmas through partial melting or through assimilation of high-Ti minerals during transport of low-Ti picritic magmas in the lunar mantle.FeO-MgO exchange between olivine and either ilmenite or armalcolite was also examined in this study. We found the FeO-MgO distribution coefficient to be effectively independent of temperature for the pressures, temperatures, and compositions explored, with an average value of 0.179 ± 0.008 for olivine/ilmenite and 0.319 ± 0.021 for olivine/armalcolite. Given the bulk composition of an overturned lunar cumulate mantle, our measured FeO-MgO distribution coefficients can be used to estimate the Mg# of coexisting minerals in armalcolite- or ilmenite-bearing harzburgite and dunite in the overturned lunar mantle. Finally, the transformation from ilmenite-bearing harzburgite to armalcolite-bearing harzburgite results in a density increase of up to 2%. Large armalcolite-bearing cumulate bodies in the upper lunar mantle may be detectable in future lunar geophysical experiments.     

不同粒径的月球橄榄石二向性反射特征研究

研究月表矿物组成和分布,对于探测月表地质构造以及月球的起源和演化具有重要的意义。因此,物质成分探测一直是月球研究的重点课题之一。尽管人类已经能够从月球采集样品进行实验室分析,但遥感技术仍然是研究月球的主要手段。文中主要目的是模拟不同粒径下橄榄石的二向性反射特征。为此,首先提出模拟不同粒径下反射特征的方法,然后利用Hapke模型和Mie散射理论对不同粒径下富铁和富镁橄榄石的二向性反射特征进行了模拟。模拟结果显示,富镁橄榄石的二向性反射率较富铁橄榄石的反射率高。最后,分析了反射率差值和等效粒径的相关性。该结论为选择探月传感器的波段组合、识别橄榄石镁铁含量提供了理论依据,也为应用遥感数据的橄榄石的判别奠定了基础。     

Analysis of mineral compositions and crater morphology on the Moon surface using Moon orbital satellite data

Analysing vertical and lateral distribution of minerals within an impact crater on lunar surface would aid in understanding the crustal compositions to a larger extent and provides clue about geological evolution of the Moon. The Chandrayaan-1 Moon Mineralogy Mapper (M³) and Lunar Reconnaissance Orbiter Camera (LROC) data have high spectral and spatial resolutions, which help in identifying the mineral compositions and morphological features of impact crater. Here we analyse mineral compositions and their correlations with crater morphology using M3 and LROC satellite data of Eijkman impact cater in SouthPole Atiken (SPA) basin. The result shows that low-Ca pyroxene (LCP) dominant rocks are identified on Central Peak (CP), Crater Floor (CF), Crater Wall (CW) and Crater Rim (CR). An olivine dominant rock is detected on the CW. Fe-Mg-spinel lithological unit is observed on the CF. The results implicate that, (i) Low-Ca pyroxene minerals could be from the lower crust during SPA main event; (ii) Presence of olivine and Fe-Mg-spinel lithology on the surface could be a later stage mafic intrusions or the lower-crustal material exposed on the surface due to major impacts.     

Mapping Lunar Olivine Using Clementine Spectral Indices and Chemical Composition Parameters

Olivine exposures at the central peak of Copernicus crater of the Earth's Moon have been confirmed by telescope observations and Clementine spectra data.Using these exposures as training sites,this stu...