一块新发现月球陨石MIL090036的岩相学和矿物学

MIL090036是一块在南极新发现的月球陨石,属于斜长岩质月球角砾岩。本文对这块陨石开展了详细的岩石学、矿物学特征观察与研究。MIL090036月球陨石具有典型的碎屑结构。碎屑包括岩屑、矿屑和玻屑。岩屑类型有斜长岩岩屑、辉长质斜长岩岩屑、辉长岩岩屑、风化角砾岩岩屑、橄长岩岩屑、微斑熔融角砾岩岩屑、复合角砾岩岩屑等;矿屑有辉石、斜长石、橄榄石、钛铁矿等;玻屑主要为长石质。基质由玻璃质、重结晶的细粒矿物和矿屑胶结组成。辉长岩岩屑中的斜长石（An81-83）和斜长岩中的斜长石(An88-93)较其他碎屑中的斜长石(An90-98)贫钙。岩屑、矿屑和长石质玻屑中的辉石相对贫铁（Fs 12-35Wo3-44 En22-79）,而含玻璃质的辉长岩岩屑中的辉石（Fs37-65Wo10-29 En21-49）与基质中的辉石（Fs18-69Wo3-45 En14-50）相对富铁。辉长岩质斜长岩中辉石成分变化范围最小（Fs24-27Wo7-14 En59-69）。矿屑橄榄石和分布于基质中的橄榄石铁镁含量（Fo57-79）相对岩屑中的橄榄石(Fo67-77) 变化范围大。橄榄石Fe/Mn比值为47-83（平均76）、辉石Fe/Mn比值为76-112（平均73）,都与月球橄榄石和月球辉石一致。岩石结构、矿物模式组合和化学成分等特征表明MIL090036是来自Apollo和Luna采样范围外的样品。对MIL090036的矿物学、岩石学和化学成分的进一步研究将能够丰富我们对月表物质组成和演化的认识。     

月壤双轴试验的剪切带离散元数值分析

土体的破坏问题一般都是从其剪切带入手进行研究的。针对真实月壤所处的环境（无水、低重力场、低气压等）和内摩擦角较大的特点,采用最近提出的1种考虑粒间抗转动作用与粒间范德华力2个因素的月壤散粒体力学接触模型,用离散单元法模拟了柔性边界条件下月球环境（含范德华力）与地球环境（不含范德华力）2种试样的双轴压缩试验,通过试样局部变形、速度场、孔隙比及转动场的变化情况研究了2种试样剪切带形成与发展。研究结果表明,剪切带的形成是试样内部应变局部化的结果,同时也伴随着试样内部颗粒相对转动的局部化,月面环境对试样的破坏形式与性状（剪切带的倾角及厚度）有显著的影响,探月工程中必须考虑到月面环境对月壤力学性质的影响。     

主应力方向和偏应力比对TJ-1模拟月壤各向异性的影响

采用空心圆柱扭剪仪对干燥TJ-1模拟月壤试样进行了应力主轴固定的定向剪切试验及不同偏应力比时主应力方向的纯旋转试验。从应力-应变关系角度出发,研究主应力方向、偏应力比对其各向异性的影响,并探讨了上述因素对TJ-1模拟月壤非共轴性的影响。试验结果表明：主应力方向和偏应力比对TJ-1模拟月壤的各向异性均有显著影响;应力主轴旋转引起的非共轴现象比定向剪切时明显,且偏应力比较小时非共轴角随应力主轴旋转呈先减小后增加的趋势,偏应力比较大时非共轴角一直减小直至试样破坏时非共轴现象消失。上述成果可弥补干砂试样非共轴领域的研究空白,并可望为将来月球上基础设施的修建提供技术支持。     

27.3-day and 13.6-day atmospheric tide and lunar forcing on atmospheric circulation

An analysis of time variations of the earth‘s length of day (LOD) versus atmospheric geopotential height fields and lunar phase is presented. A strong correlation is found between LOD and geopotential height from which a close relationship is inferred and found between atmospheric circulation and the lunar cycle around the earth. It is found that there is a 27.3-day and 13.6-day east-west oscillation in the atmospheric circulation following the lunar phase change. The lunar revolution around the earth strongly influences the atmospheric circulation. During each lunar cycle around the earth there is, on average, an alternating change of 6.8-day-decrease, 6.8-day-increase, 6.8-day-deerease and 6.8-day-increase in atmospheric zonal wind, atmospheric angular momentum and LOD. The dominant factor producing such an oscillation in atmospheric circulation is the periodic change of lunar declination during the lunar revolution around the earth. The 27.3- day and 13.6-day atmospheric oscillatory phenomenon is akin to a strong atmospheric tide, which is different from the weak atmospheric tides, diurnal and semidiurnal, previously documented in the literature. Also it is different from the tides in the ocean in accordance with their frequency and date of occurrence. Estimation shows that the 27.3-day lunar forcing produces a 1-2 m s^-1 change in atmospheric zonal wind. Therefore, it should be considered in models of atmospheric circulation and short and middle term weather forecasting. The physical mechanism and dynamic processes in lunar forcing on atmospheric circulation are discussed.     

Impact of lunar cycle and swell on the daily catch rate of western rock lobster (Panulirus cygnus) using time series modelling

The western rock lobster fishery is one of the most valuable single‐species fisheries in Australia, valued at AU$300 million per year. The impact of environmental factors such as lunar cycle and swell on the daily catch rate of the western rock lobster (Panulirus cynus) is of particular interest in the stock assessment and management of the fishery. The variation in daily catch rates was examined for two periods (migrating period November‐January, non‐migrating period February‐June), at different depths in three management zones for three categories of lobster (undersize, legal size, and setose). Regression and transfer function models for relationships between catch rates and environmental data were considered and compared. The lunar cycle has a significant impact on the daily catch rates with c. 30% lower catch rate during the full moon and c. 20% higher catches near the new moon. This impact occurs mainly during the non‐migrating period both in deep water (40–100 m) and shallow water (<40 m). The swell on the day before fishing was also shown to be significantly related to the catch rate with an increase of c. 10–15% for an increase in swell from light to moderate or moderate to high. These environmental factors can be used to standardise catch rates to provide an improved abundance index for stock assessment. Also, management closures are being considered for 3–5 days over the low catch rate, full moon period to reduce fishing costs and lower fishing effort.     

The distribution of pelagic seabirds in relation to the oceanic environment of Gough Island

The distribution and the abundance of flying seabirds are described in relation to the marine environment near Gough Island in the south Atlantic Ocean. Results from a combined seabird, hydrographic and hydro-acoustic survey are assessed in order to highlight possible biotic-abiotic associations. In accordance with recently published work, the macroscale abundance and species composition of avifauna are explained in terms of Gough Island's position between two major biogeographic zones and by the island's utilization as a breeding site for pelagic seabirds. On the mesoscale, seabird abundance was greatest in areas of hydrographical variability, where results from acoustic transects and net hauls suggested concentration of potential food items (i.e. zooplankton and micronekton).     

月表形貌特征研究进展及趋势分析

在月球探测及科学研究过程中,对月表形貌特征的认识和分析是月球探测计划的关键任务之一,有助于理解和揭示月球的形态特征及空间分异规律,对于分析月球岩石构造、估算月表年龄、反演月壤厚度、恢复月球的起源和演化历史等都具有重要意义。从月表形貌特征的塑造及表达、宏观特征的分析与定量刻画、月表撞击坑的识别与分类及空间分异特征等几方面进行了归纳和分析,提出了未来月表形貌的研究方向,包括全月球形貌特征的多级分区划分、撞击坑类型的划分、全月球撞击坑空间分异特征及规律的研究、基于撞击坑空间分布探讨月球演化、基于形貌特征的比较行星学研究等。     

月球地形测绘和月球大地测量(1)

从十九世纪六十年代以来的几十年中 ,人类一直试图发射航天器 ,以对月球 ,特别是它的远月面进行探测。美国和前苏联发射了各类月球探测器达七十余个 ,对月球进行探测 ,至今几乎已经完成了对月球重要的地学勘查 ,其中包括对全部月面的地形测绘和月球重力场测定。本节对月球航天探测的主要情况作了介绍 ,对月球的不同起源学说作了简要回顾 ,对月球的几何和物理特征作了介绍     

SIMS Pb/Pb dating of Zr-rich minerals in lunar meteorites Miller Range 05035 and LaPaz Icefield 02224:Implications for the petrogenesis of mare basalt

Miller Range (MIL) 05035 and LaPaz Icefield (LAP) 02224 are unbrecciated lunar basalt meteorites. In this report, we studied their petrography and mineralogy and made in situ uranogenic Pb/Pb dating of Zr-rich minerals. Petrography and mineralogy of these two lunar meteorites are consistent with previous investigations. The zirconolite Pb/Pb age of MIL 05035 is 3851±8 Ma (2σ), in excellent agreement with previous reports. This age suggests that MIL 05035 could be paired with Asuka 881757, a low-Ti mare basalt meteorite. The magmatic event related to MIL 05035 was probably due to the late heavy impact bom- bardment on the moon around 3.9 Ga. One baddeleyite grain in LAP 02224 shows a large variation of Pb/Pb age, from 3109±29 to 3547±21 Ma (2σ), much older than the whole-rock age of the same meteorite (~3.02±0.03 Ga). The other baddeleyite grain in LAP 02224 has an age of 3005±17 Ma (2σ). The result indicates that the minimum crystallization age of LAP 02224 is ~3.55 Ga and the younger ages could reflect late thermal disturbance on U-Pb system.     

相干算法提取嫦娥数据月表地质特征

经典的边缘提取算法可从月球影像数据中提取出月表的构造特征, 但难以提取出与月貌有关的特征信息.本文提出的相干法月球影像地质特征提取技术, 其基本思想是基于相干运算来考察图像上像素或像素组之间的相似性, 以获取月表的构造特征和月貌特征.该方法已经应用在嫦娥一号月球探测器获取的部分影像数据上, 相比于几种常规的边缘提取方法, 本方法优势明显, 不仅能有效地提取环形构造和线性构造等地质特征, 还可以很好地提取月貌特征, 对具有一定规模的小直径撞击坑的识别也有不错的效果.该方法可以用于计算机自动识别或辅助手工解译月表构造, 划分月貌单元等研究.