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11.
林东陨石发现于我国内蒙古地区,被划分为LL5-6型普通球粒陨石角砾岩。本项工作对林东陨石开展了深入的岩石矿物学分析,提出将其重新划分为表土角砾岩的新观点。林东陨石主要由大至厘米级的角砾、以及微米大小的细粒基质两部分构成。不同角砾之间,表现出明显差异的岩石结构,反映了不同程度的热变质,岩石类型变化范围为4～6型。角砾以岩屑为主,还含有残余球粒和粗粒的矿物碎屑。不同岩石类型角砾的橄榄石Fa值（29.7 mol%～30.5 mol%）、低钙辉石Fs值（24.9 mol%～26.1 mol%）、以及铁纹石的Co含量（2.38%～2.51%）等,表明这些角砾均为低铁低金属的LL化学群,判断其来自同一小行星母体。林东陨石的细粒基质主要由微米大小的矿物碎屑固结而成,颗粒之间有较多的孔隙,整体较为松散。细粒基质的化学组成与岩石角砾中的矿物颗粒相同,应当是后者的机械粉碎产物。据此推测林东陨石的母体是一颗LL群小行星,表面经历了长期的小天体碰撞,形成各种岩屑和微细矿物晶屑,然后固结成林东陨石表土角砾岩。林东陨石的发现为研究小行星表面的演化历史,以及太阳风辐射等太空风化提供了珍贵样品,并为我国小行星探测提供可供对照的对象。 相似文献
12.
Achim A. Beylich Else Kolstrup Tage Thyrsted Niklas Linde Laust B. Pedersen Lars Dynesius 《Geomorphology》2004,57(3-4):303-319
In Latnjavagge, a 9-km2 drainage basin with homogeneous lithology in periglacial northern Swedish Lapland, water balance, water chemistry and radio magnetotelluric geophysical investigations along selected profiles were integrated with assessment of regolith thickness as well as of ground frost conditions within the basin. In combination with direct field observations, the geophysical profiles demonstrated presence of relatively thin regolith in most of the investigated area, yet in some parts, the bedrock was located deeper and locally was not detected at 40-m depth. TDS values of the water were generally very low. The areas that contributed with the lowest ion concentrations were cold and had a thin regolith, whereas there were higher concentrations in water that drained radiation exposed slopes with earlier thaw and thicker regolith. The low resistivities found along the profiles in the geophysical investigations in combination with the relatively higher TDS values found in related runoff and subsurface water samples showed that larger volumes of ice-rich frozen ground were not found along the investigated profiles in late August. 相似文献
13.
We have constructed an experiment to perform bidirectional reflectance distribution function (BRDF) measurements of laboratory samples, and have used the experiment to characterize a sample of JSC-1 lunar regolith simulant. Characterizations relied on in-plane BRDF measurements in visible and near-infrared (NIR) bandpasses. The optical properties of the simulant sample were found to be similar to those observed for bright, lunar highland regions. Reflectance models (Hapke 1981. Bidirectional reflectance spectroscopy 1. Theory. J. Geophys. Res. 86(B4), 3,039−3,054; 1984. Bidirectional reflectance spectroscopy 3. Correction for macroscopic roughness. Icarus 59, 41−59; 1986. Bidirectional reflectance spectroscopy 4. The extinction coefficient and the opposition effect. Icarus 67, 264−280; 2002. Bidirectional reflectance spectroscopy 5. The coherent backscatter opposition effect and anisotropic scattering. Icarus 157, 523−534) made excellent fits to fixed incidence angle, variable emission angle data sets. However, the models were not found to extrapolate well to fixed, near-zero phase angle data at varying incidence angles, and no solutions were found that provided simultaneous, high quality fits to the two types of data sets. Except for the single-scattering albedo, the best-fit parameters of the fixed incidence angle data were statistically the same in the visible and NIR. Correlations between the reflectance model parameters were systematically examined, and strong correlations were found between single-scattering albedo and the two two-stream Henyey-Greenstein scattering parameters and, to a lesser extent, the small-scale mean surface roughness. 相似文献
14.
Relief inversion has been invoked to explain a number of geomorphic features of the martian surface. Terrestrial relief inversion occurs when former depressions become elevated because their fill is more resistant to erosion than the surrounding terrain. It is a common product of long-term landscape evolution on Earth, especially in relatively stable intra-cratonic settings and flat, or near flat lying successions. The inverted relief will preserve relicts of former land surfaces and is therefore older than the surrounding terrain. Relief inversion can occur by a range of processes, including infill of depressions by intrinsically resistant material, selective secondary cementation via diagenesis and weathering, or surface armouring. We examine a number of possible cases of inverted relief on Mars that appear to have formed by these three processes. We suggest that the most likely cementing agents for surface induration are iron oxides, silica, and sulfates. Possible cementation mechanisms include fluid mixing during regional groundwater flow, cooling of hydrothermal or basinal fluids as they near the surface, and evaporation and sublimation of near surface water. Wind action appears the most common erosive process on Mars capable of the regional landscape lowering necessary for relief inversion to occur, unlike on Earth where both deflation and runoff are important. Preliminary crater densities of selected features show that the tops of the proposed inverted relief have considerably more craters than the surrounding plains, as is predicted by the inversion hypothesis. More accurate dating of inverted surfaces and the adjacent areas may provide a simple way of measuring the degree of erosion over time in at least some areas of Mars. 相似文献
15.
The regolith of other planetary bodies, such as the Moon and Mars, is rich in inorganic elements that could potentially be exploited for space applications. Lithotrophic microorganisms that are capable of utilising rocks as a growth substrate, and facilitate the extraction of elements, are ideal candidates for in-situ resource use. Of particular interest are the cyanobacteria, which have been suggested for applications, such as oxygen, fuel and biomass production, nutrient acquisition, and feedstock provisions. In this study, Gloeocapsa strain OU_20, isolated from a rock-dwelling community exposed to low Earth orbit; Leptolyngbya strain OU_13 and Phormidium strain OU_10, both isolated from a rock-dwelling community exposed to Mars simulated conditions; Chroococcidiopsis 029; Arthrospira platensis; Synechococcus elongatus; and Anabaena cylindrica, were examined as potential organisms for space in-situ resource use. Volcanic rocks, including basalt (low in SiO2) analogous to martian and lunar basalt, rhyolite (high in SiO2), and anorthosite analogous to lunar regolith were used as growth substrates. The growth rate and rock dissolution were significantly lower with rhyolite demonstrating the importance of silica content in defining the potential for in-situ resource use. Biological weathering resulted in the release of bio-essential elements from the rock matrix, highlighting the potential of cyanobacteria for applications such as bio-mining and nutrient acquisition, on other planets. A. cylindrica produced the maximum biomass with the three rock-types and the optimal value was obtained with the basalt. Exposure experiments demonstrated that A. cylindrica, Chroococcidiopsis 029, Gloeocapsa strain OU_20, Phormidium strain OU_10, and Leptolyngbya strain OU_13 were able to survive 28 days of exposure to desiccation and Mars simulated conditions, which is beneficial in case of system malfunction and for storage. The results from this study indicate that cyanobacteria can potentially be used for in-situ planetary resource acquisition. 相似文献
16.
Soil erosion on steepland hillslopes in Taranaki, New Zealand, where landsliding is the dominant erosion form, was investigated by comparing mean regolith depths between first-order basins that have had their forest cover removed for different periods of time. Regolith depth and slope angle data were collected along 19 profile lines and 30 profile lines from steepland basins that had been deforested for 10 and 85 years, respectively. These profile lines were subdivided into a total of 236 profile segments of relatively linear slope angle and uniform regolith depth, that averaged 17·5 m in length. The depth of pre-existing regolith on post-deforestation landslide sites is estimated from a regression of regolith depth on slope angle for undisturbed (non-landslide) profile segments. Regolith depletion on landslide sites is in turn estimated by subtracting the depth of regolith on landslide sites from the estimate of pre-existing regolith depth. Regolith depletion by post-deforestation landslides, averaged over the entire length of profile lines, gives an estimate of average surface lowering. For the area deforested for 85 years, average surface lowering by post-deforestation landslides is 0·15 ± 0·04 m, and is the same as the difference in mean depth of 0·15 ± 0·11 m between this area and the area deforested for 10 years. Erosion of regolith from hillslopes by processes other than landsliding appears to be minimal. The 0·15 m average surface lowering represents a regolith depletion rate of 1·8 ± 0±5 mm yr?1. For hillslopes steeper than 28°, where all post-deforestation landslides occur, average surface lowering is 0·20 ± 0·05 m, and the regolith depletion rate is 2±4 · 0±6 mm yr?1. Average surface lowering is greatest at 0·23 ± 0·07 m on hillslopes steeper than 32° where most post-deforestation landslides occur. Here, the regolith depletion rate is 2·7 ± 0·8 mm yr?1. A large-magnitude, low-frequency storm in March 1990, produced an average surface lowering of 0·041 m. There were proportionately more landslides in the area deforested for 10 years, illustrating the importance of previous erosion history of hillslopes on the spatial distribution of landslides. There were also comparatively few landslides on steeper hillslopes because previous lower magnitude storms had already removed much of the deeper regolith. 相似文献
17.
运用EH4电磁测深法布置剖面,结合岩矿石电性参数及地质资料分析,对剖面实测数据进行反演,较准确地识别出隐伏塌陷区、煤矿采空区及松散浮土层等地质异常区域及范围,较好地确定可能的地质灾害。 相似文献
18.
Multispectral polarimetry as a tool to investigate texture and chemistry of lunar regolith particles
Yuriy Shkuratov Nikolay Opanasenko Yevgen Grynko Viktor Korokhin Gorden Videen Urs Mall 《Icarus》2007,187(2):406-416
We report results of telescope polarimetric imaging of the Moon with a CCD LineScan Camera at large phase angles, near 88°. This allows measurements of the polarization degree with an absolute accuracy better than 0.3% and detection of features with polarization contrast as small as 0.1%. The measurements are carried out in two spectral bands centered near 0.65 and 0.42 μm. We suggest characterizing the lunar regolith with the parameter a(Pmax)A, where Pmax,A, and a are the degree of maximum polarization, albedo, and the parameter describing the linear regression of the correlation Pmax-A. The parameter bears significant information on the particle characteristic size and packing density of the lunar regolith. We also suggest characterizing the lunar regolith with color-ratio images obtained with a polarization filter at large phase angles. We here consider the color-ratios C||(0.65/0.42 μm) and C⊥(0.65/0.42 μm). Using light scattering model calculations we show that the color-ratio images obtained with a polarization filter at large phase angles suggest a new tool to study the lunar surface. In particular, it turns out that the color-ratios C||(0.65/0.42 μm) and C⊥(0.65/0.42 μm) are sensitive to somewhat different thicknesses of the surfaces of regolith particles. We consider the applicability of the Hubble Space Telescope, the Very Large Telescope (ESO), and a spacecraft on a lunar polar orbit for polarimetric observations of the lunar surface. 相似文献
19.
Images of Eros from the NEAR Shoemaker spacecraft reveal bright and dark albedo features on steep crater walls unlike markings previously observed on asteroids. These features have been attributed to the downslope movement of space-weathered regolith, exposing less weathered material (Science 292 (2001) 484; Meteor. Planet. Sci. 36 (2001) 1617; Icarus 155 (2002) 145). Here we present observations of the interiors of large craters (>1 km in diameter) to test this hypothesis and constrain the origin of the features. We find that bright regions in these craters correspond to steep slopes, consistent with previous work. The geographic distribution of craters with albedo variations shows no pattern and does not resemble the distribution of ponds, another phenomenon on Eros attributed to regolith movement. Shadows and other indications of topography are not observed at feature boundaries, implying that the transported layer is ?1 m thick. The presence of multiple bright and dark units on long slopes with sharp boundaries between them suggests that mobilized regolith may be halted by frictional or other effects before reaching the foot of the slope. Features on crater walls should darken at the same rate as bright ejecta deposits from crater formation; the lack of observed, morphologically fresh craters with bright interiors or ejecta suggests that the albedo patterns are younger than the most recently formed craters greater than about 100 m in diameter. Smaller or micrometeorite impacts, which would not necessarily leave evident deposits of bright ejecta, remain possible causes of albedo patterns. Although their effectiveness is difficult to assess, electrostatic processes and thermal creep are also candidates. 相似文献
20.
We calculate new estimates of ground-ice stability and the depth distribution of the ice table (the depth boundary between ice-free soil above and ice-cemented soil below) and compare these theoretical estimates of the distribution of ground ice with the observed distribution of leakage neutrons measured by the Neutron Spectrometer instrument of the Mars Odyssey spacecraft's Gamma Ray Spectrometer instrument suite. Our calculated ground-ice distribution contains improvements over previous work in that we include the effects of the high thermal conductivity of ice-cemented soil at and below the ice table, we include the surface elevation dependence of the near-surface atmospheric humidity, and we utilize new high resolution maps of thermal inertia, albedo, and elevation from Mars Global Surveyor observations. Results indicate that ground ice should be about 5 times shallower than in previous predictions. While results are dependent on the atmospheric humidity, depths are generally between a few millimeters and a few meters with typical values of a few centimeters. Results are also geographically similar to previous predictions with differences due to the higher resolution of thermal inertia and the inclusion of elevation effects on humidity. Comparison with the measured epithermal-neutron count rates in the southern hemisphere indicate that the geographic distribution of the count rate is best correlated with ground ice in equilibrium with 10 to 20 pr μm (precipitable micrometers) column abundance of atmospheric water, assuming a uniform distribution with CO2; however, given the uncertainties, 5 to 30 pr μm also may be viable. This water abundance represents a longer-term average over 100 to 1000 yr. There is a high degree of correlation between the depth of the ice table and the epithermal count rate that agrees remarkably well with predicted count rates as a function of ice-table depth. These results indicate that ground ice in the upper meter of the martian soil is in diffusive equilibrium with the atmosphere. Since ground ice in this depth zone is expected to undergo saturation/desiccation cycles with orbital variations, this ice should be younger than about 500 kyr and was emplaced under similar cold and dry climate conditions of today. Remaining differences between the predicted depths of the ice table and those inferred from the neutron data are likely to be due to subpixel heterogeneity in the martian surface including the presence of rocks, slopes, and patches of soil with varying thermophysical properties. 相似文献