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1.
撞击坑统计定年法的基本原理是首先得到月球表面撞击坑密度分布的一般规律(即产率函数),然后将其应用到Apollo和Luna任务采样的区域中,得到大干特定直径(常用1 km)的撞击坑密度,然后在该密度和样品的同位素年龄之间建立函数关系(即年代函数).在对没有样品的地质单元进行年龄分析时,首先从遥感影像解译撞击坑,然后根据产率函数求解大于指定直径撞击坑的密度,最后将其代入年代函数中求解该区域的地质年龄.根据其它行星与月球撞击环境的差异等因素,该方法已经推广到其它行星表面地质年龄的研究中.本文详细分析了撞击坑统计定年方法的原理,以及在应用中需要注意的问题.  相似文献   

2.
月表撞击坑自动识别与提取的新方法及其应用   总被引:2,自引:0,他引:2       下载免费PDF全文
月表撞击坑是月球最显著的地质构造特征。随着不同月球探测器探测数据的丰富与数据质量的提高,月表地质信息挖掘成为月球科学领域重要的研究内容。月表分布广泛的撞击事件的撞击机理研究和月表地质单元的地质年龄的判定等科学问题都离不开对撞击坑的研究。因此,对撞击坑进行识别和特征参数提取是挖掘以上月表地质隐含信息的基础和关键。针对目前用于撞击坑识别和特征参数提取的方法存在效率低下、应用范围有限等种种缺陷,提出了一种新的月表环形构造识别和特征参数提取方法,并且实现了定量自动化处理。首先,根据撞击坑环形构造特征,利用坡度指数提取坑壁多边形矢量要素;其次,提出并采用环形构造最小外包矩形法提取撞击坑的伪中心与伪直径;然后,以伪中心为中心点向外搜寻并确定撞击坑坑缘顶点;最后,利用三点定圆法确定撞击坑的中心位置和直径大小。以嫦娥一号CCD相机影像数据和利用CCD立体相机制作的DEM数据为数据源,选取不同区域、不同类型的月表撞击坑进行试验,并将计算结果与目前研究成果进行对比。结果验证表明,此方法可以推广到月表其他表面,并可应用于月表撞击坑形成机理研究和利用撞击坑大小频率分布测量的方法确定月表地质单元的地质年龄工作中。  相似文献   

3.
撞击坑是月表最典型的地质单元,其溅射物作为撞击坑的坑外组成部分可分布到距离坑中心10个直径距离之外的区域,因此撞击溅射物也是月球地质编图中最重要的表达要素之一。本文使用月球勘测轨道器(LRO)的激光高度计(LOLA)数据、广角相机(WAC)影像、窄角相机(NAC)影像以及Clementine的UVVIS多光谱数据,研究了哥白尼纪正面月海区直径31km的Kepler撞击坑和背面月陆区直径30km的Necho撞击坑。哥白尼纪撞击坑溅射沉积物可以分为三个相:连续溅射沉积相(CE)、不连续溅射沉积相(DE)和辐射纹(CR)。连续溅射沉积相分布在最大约2.6个半径范围之内,不连续溅射沉积相分布在最大近11个半径范围之内,辐射纹分布在最大近29个半径范围之内。本文强调了多源数据结合在识别撞击坑溅射沉积物中的作用,对Kepler坑和Necho坑溅射沉积物进行了填图,不对称分布的特征表明这两个坑可能形成于倾斜撞击。  相似文献   

4.
“嫦娥一号”第一幅月面遥感影像撞击坑特征   总被引:1,自引:0,他引:1  
撞击坑是月表的主要地貌形态,按普通碗状型、中心隆起型、平底型及同心圆型4种类型描述"第一幅月面图像"上月表撞击坑的形态特征.应用遥感专业图像处理软件,结合白赛尔大地主题反算法,实现撞击坑分布及直径信息提取.研究发现,研究区域的撞击坑直径主要集中在300~700 m.而且撞击坑空间分布不均匀,直径越小,分布越密集.  相似文献   

5.
撞击坑统计技术在行星表面定年应用中的误区   总被引:1,自引:0,他引:1  
撞击坑大小-频率统计技术在其理论基础与实际应用中存在一定的局限性,且尚未引起国内外行星地质学界的广泛关注.使用该技术分析行星表面的年龄时,应注意:(1)由于晚期大轰击事件的存在,该技术不能用于估算内太阳系天体表面老于~38亿年的地质体的年龄;(2)由于内、外太阳系的撞击历史不同,不能直接使用月球上的撞击坑的产生方程估算外太阳系天体表面地质单元的绝对模式年龄;(3)由于二次撞击坑的干扰,须谨慎使用小撞击坑统计估算年龄;(4)分析撞击坑统计的结果前,首先需分析统计区的饱和状态;(5)避免使用太阳入射角小的影像数据统计撞击坑,避免选择地形复杂的区域作为统计区.另外,建议优先使用相对分布法、并结合累积分布法分析撞击坑统计的结果.  相似文献   

6.
月表典型区撞击坑形态分类及分布特征   总被引:2,自引:0,他引:2       下载免费PDF全文
月球表面环形构造主要有撞击坑、火山口和月海穹窿3种,其中撞击坑分布最广泛,是研究月表环形构造的主要内容。由于月表撞击坑数量大、种类多及其形成伴随着整个月球地质的演化过程,因此这种月表地形地貌比较完整地记录了月球表面地貌随时间的改造过程以及改造类型。文中通过研究撞击坑遥感影像及形貌特征,总结归纳为简单型、碗型、平底型、中央隆起型、同心环型、复杂型及月海残留型7种撞击坑类型,用来描述月表典型区域撞击坑的形态特征。从结构和物质两方面进行了月表典型区域撞击坑的形态地貌参数提取,综合利用嫦娥一号CCD 影像数据、LROC数据,得到了该区域撞击坑形态数据(坑底、坑唇、坑壁、坑缘、溅射物覆盖层、中央峰)和形态测量数据(直径、深度、地理位置)。研究发现,LQ 4地区的撞击坑分布可分为月陆区和月海区,月陆区的撞击坑多以中小型撞击坑为主,其分布密度极高,形成年代较早,月海区撞击坑多为年轻的撞击坑,分化程度较低,分布密度也较低。  相似文献   

7.
Apollo 11和嫦娥四号(Chang'E-4)是人类探月历史上的里程碑,它们的着陆区分别位于月球正面和背面.对两个着陆区内不同退化程度撞击坑的统计和对比分析有助于揭示研究区域的地质年龄和演化历史,对月球地质研究有着重要的意义.本文使用LRO NAC影像和DTM产品对两个着陆区附近1 km2范围内撞击坑的退化进行分析...  相似文献   

8.
撞击坑统计方法是估计行星表面年代的一种有效方法。利用小尺度撞击坑大小频率分布测定撞击年龄,并分析了计算模型的不确定性、撞击坑的退化、次级撞击坑影响等相关问题。选用嫦娥二号获取的虹湾地区高精度影像数据进行验证,确定该区域退化参数为350 m,直径小于30 m时次级撞击坑密集分布,使用350 m以上的撞击坑计算得到撞击年龄为3.16 Ga,误差控制在0.1 Ga以内。  相似文献   

9.
肖智勇 《地质学报》2021,95(9):2641-2661
在太阳系的形成和演化过程中,发生在天体物质间的撞击作用是最重要的地质过程之一。撞击构造是地外天体表面最常见的地貌单元,大部分天体的地貌演化主要受撞击作用控制。撞击过程产生的温度、压力和应变速率比岩石圈内的其他地质过程高多个数量级,形成广泛分布的撞击产物,如气化物、熔融物、冲击变质和变形等。虽然撞击过程转瞬即逝,撞击作用向天体注入能量并改变其内、外结构,对天体的圈层系统产生长远影响。持续撞击在天体表面累积了大量的撞击坑,撞击坑的空间分布反映了受外来撞击的历史。内太阳系在~3.8 Ga前的撞击频率更高,但是大量撞击盆地是否灾变式的密集形成仍在持续争议;~3.8 Ga以来的撞击频率趋于稳定,但是缺乏具有明确事件指代性的标定样品。在同一天体上,撞击坑的空间密度指示了相应地质单元的形成时间,因此撞击坑统计常被用于估算地外天体表面地质单元的相对年龄。基于月球软着陆探测任务返回的样品,前人已约束了不同直径的月球撞击坑的形成频率,进而建立了使用撞击坑统计估算月球表面地质单元的绝对模式年龄的方法。另外,内太阳系天体可能经历了相似的撞击历史,因此地-月系统的撞击频率已被缩放至其他类地行星。撞击坑统计是探索...  相似文献   

10.
姚美娟  陈建平  王翔  徐彬 《岩石学报》2016,32(1):119-126
撞击坑是月球表面广泛分布的重要构造形态,占据了月球表面的大部分面积。撞击坑的直径差别很大,从几微米到数百千米,其退化程度与形成年代具有密切关系。为了研究不同地质年代形成的撞击坑直径大小及其演化规律,需采用量化分级方法对大小不同的撞击坑进行定量分级和统计分析。本文在月表撞击坑数据库LU60645GT和Lunar_Impact_Crater_Database(2011)的基础上,结合数据库中撞击坑的直径、深度和年代信息,利用最优分割分级法对撞击坑直径进行定量化分级,并根据分级结果,综合分析撞击坑几何形态特征及其演化规律。研究结果表明,撞击坑形态特征的演化与年代有密切的关系。在相同级别、相同地体下,撞击坑形成的年代越早,其形态特征的精细结构退化程度越明显,只保留了大体的几何形状;而在不同级别、相同地体、相同年代下的撞击坑形态特征则由简单逐渐变为复杂,坑物质也逐渐变得复杂。  相似文献   

11.
This study addresses the issue of what fraction of the impact glass in the regolith of a lunar landing site derives from local impacts (those within a few kilometers of the site) as opposed to distant impacts (10 or more kilometers away). Among 10,323 fragments from the 64-210-μm grain-size fraction of three Apollo 16 regolith samples, 14% are impact glasses, that is, fragments consisting wholly or largely of glass produced in a crater-forming impact. Another 16% are agglutinates formed by impacts of micrometeorites into regolith. We analyzed the glass in 1559 fragments for major- and minor-element concentrations by electron probe microanalysis and a subset of 112 of the fragments that are homogeneous impact glasses for trace elements by secondary ion mass spectrometry. Of the impact glasses, 75% are substantially different in composition from either the Apollo 16 regolith or any mixture of rocks of which the regolith is mainly composed. About 40% of the impact glasses are richer in Fe, Mg, and Ti, as well as K, P, and Sm, than are common rocks of the feldspathic highlands. These glasses must originate from craters in maria or the Procellarum KREEP Terrane. Of the feldspathic impact glasses, some are substantially more magnesian (greater MgO/FeO) or have substantially lower concentrations of incompatible elements than the regolith of the Apollo 16 site. Many of these, however, are in the range of feldspathic lunar meteorites, most of which derive from points in the feldspathic highlands distant from the Procellarum KREEP Terrane. These observations indicate that a significant proportion of the impact glass in the Apollo 16 regolith is from craters occurring 100 km or more from the landing site. In contrast, the composition of glass in agglutinates, on average, is similar to the composition of the Apollo 16 regolith, consistent with local origin.  相似文献   

12.
月球表面定年研究对于理解和重建月球地质演化历史具有关键作用,撞击坑尺寸频率分布法(CSFD)是通过统计区域内不同尺寸撞击坑密度得到特定地质单元的绝对地质年龄。雨海北部地区(LQ 4)包括雨海北部、冷海西部地区以及风暴洋东北部等月海,位于雨海西北边缘的虹湾是中国嫦娥三号卫星预选软着落区,文中综合使用3种方法从影像和地形数据中自动提取了该区内的撞击坑。利用Clementine光谱数据对雨海北部和风暴洋东北部内玄武岩进行了分区,利用撞击坑尺寸频度法(CSFD)法得到每个玄武岩分区内的定年结果。对比该地区之前的定年数据后发现,使用自动识别结果得到的各分区定年结果新老整体趋势上与之前研究结果基本一致,但存在一定偏差。根据自动识别定年结果,认为该地区玄武岩新老顺序大致为:雨海东部(3.56 Ga)-虹湾(3.38 Ga)-风暴洋东北部(2.74 Ga)-雨海西部(2.63 Ga)-柏拉图坑(2.37 Ga)。结合撞击坑自动识别技术和CSFD法,形成了一条利用影像和地形遥感数据快速得到月球表面地质年龄的方法,为月球年代学研究提供一种新途径。  相似文献   

13.
We present compositional data for 358 lithic fragments (2-4-mm size range) and 15 soils (<1-mm fines) from regolith samples collected at the Apollo 12 site. The regolith is dominated by mare basalt, KREEP impact-melt breccias (crystalline and glassy), and regolith breccias. Minor components include alkali anorthosite, alkali norite, granite, quartz monzogabbro, and anorthositic rocks from the feldspathic highlands. The typical KREEP impact-melt breccia of Apollo 12 (mean Th: 16 μg/g) is similar to that of the Apollo 14 site (16 μg/g), 180 km away. Both contain a minor component (0.3% at Apollo 12, 0.6% at Apollo 14) of FeNi metal that is dissimilar to metal in ordinary chondrites but is similar to metal found in Apollo 16 impact-melt breccias. The Apollo 12 regolith contains another variety of KREEP impact-melt breccia that differs from any type of breccia described from the Apollo sites in being substantially richer in Th (30 μg/g) but with only moderate concentrations of K. It is, however, similar in composition to the melt breccia lithology in lunar meteorite Sayh al Uhaymir 169. The average composition of typical mature soil corresponds to a mixture of 65% mare basalt, 20% typical KREEP impact-melt breccia, 7% high-Th impact-melt breccia, 6% feldspathic material, 2.6% alkali noritic anorthosite, and 0.9% CM chondrite. Thus, although the site was resurfaced by basaltic volcanism 3.1-3.3 Ga ago, a third of the material in the present regolith is of nonmare origin, mainly in the form of KREEP impact-melt breccias and glass. These materials occur in the Apollo 12 regolith mainly as a result of moderate-sized impacts into surrounding Fra Mauro and Alpes Formations that formed craters Copernicus (93 km diameter, 406 km distance), Reinhold (48 km diameter, 196 km distance), and possibly Lansberg (39 km diameter, 108 km distance), aided by excavation of basalt interlayers and mixing of regolith by small, local impacts. Anomalous immature soil samples 12024, 12032, and 12033 contain a lesser proportion of mare basalt and a correspondingly greater proportion of KREEP lithologies. These samples consist mainly of fossil or paleoregolith, likely ejecta from Copernicus, that was buried beneath the mixing zone of micrometeorite gardening, and then brought to the near surface by local craters such as Head, Bench, and Sharp Craters.  相似文献   

14.
We report the results of a SIMS U-Pb study of 112 zircons from breccia samples from the Apollo 14 and 17 landing sites. Zircon occurs in the breccia matrices as rounded, irregular shaped, broken and rarely euhedral grains and as constituent minerals in a variety of lithic clasts ranging in composition from ultra-mafic and mafic rocks to highly evolved granophyres. Crystallisation of zircon in magmatic rocks is governed by the zirconium saturation in the melt. As a consequence, the presence of zircon in mafic rocks on the Moon implies enrichment of their parent melts in the KREEP component. Our SIMS results show that the ages of zircons from mafic to ultramafic clasts range from ca. 4.35 Ga to ca. 4.00 Ga demonstrating multiple generations of KREEPy mafic and ultramafic magmas over this time period. Individual zircon clasts in breccia matrices have a similar age range to zircons in igneous clasts and all represent zircons that have been incorporated into the breccia from older parents. The age distributions of zircons from breccias from both the Apollo 14 and Apollo 17 landing sites are essentially identical in the range 4.35-4.20 Ga. However, whereas Apollo 14 zircons additionally show ages from 4.20 to 3.90 Ga, no zircons from Apollo 17 samples have primary ages less than ca. 4.20 Ga. Also, in contrast to previous suggestions that the magmatism in the lunar crust is continuous our results show that the zircon age distribution is uneven, with distinct peaks of magmatic activity at ca. 4.35 Ga, ca. 4.20 Ga in Apollo 14 and 17 and a possible third peak in zircons from Apollo 14 at ca. 4.00 Ga. To explain the differences in the zircon age distributions between the Apollo 14 and 17 landing sites we propose that episodes of KREEP magmatism were generated from a primary reservoir, and that this reservoir contracted over time towards the centre of Procellarum KREEP terrane. We attribute the peaks in KREEP magmatism to impact induced emplacement of KREEP magma from a primary mantle source or to a progressive thermal build-up in the mantle source until the temperature exceeds the threshold for generation of KREEP magma, which is transported into the crust by an unspecified possibly plume-like process.  相似文献   

15.
Since the Apollo 14 mission delivered samples of the Fra Mauro formation, interpreted as ejecta of the Imbrium impact, defining the age of this impact has emerged as one of the critical tasks required for the complete understanding of the asteroid bombardment history of the Moon and, by extension, the inner Solar System. Significant effort dedicated to this task has resulted in a substantial set of ages centered around 3.9 Ga and obtained for the samples from most Apollo landing sites using a variety of chronological methods. However, the available age data are scattered over a range of a few tens of millions of years, which hinders the ability to distinguish between the samples that are truly representative of the Imbrium impact and those formed/reset by other, broadly contemporaneous impact events. This study presents a new set of U-Pb ages obtained for the VHK (very high K) basalt clasts found in the Apollo 14 breccia sample 14305 and phosphates from (i) several fragments of impact-melt breccia extracted from Apollo 14 soil sample 14161, and (ii) two Apollo 15 breccias 15455 and 15445. The new data obtained for the Apollo 14 samples increase the number of independently dated samples from this landing site to ten. These Apollo 14 samples represent the Fra Mauro formation, which is traditionally viewed as Imbrium ejecta, and therefore should record the age of the Imbrium impact. Using the variance of ten ages, we propose an age of 3922 ± 12 Ma for this event. Samples that yield ages within these limits can be considered as possible products of the Imbrium impact, while those that fall significantly outside this range should be treated as representing different impact events. Comparison of this age for Imbrium (determined from Apollo 14 samples) with the ages of another eleven impact-melt breccia samples collected at four other landing sites and a related lunar meteorite suggests that they can be viewed as part of Imbrium ejecta. Comprehensive review of 40Ar/39Ar ages available for impact melt samples from different landing sites and obtained using the step-heating technique, suggests that the majority of the samples that gave robust plateau ages are indistinguishable within uncertainties and altogether yield a weighted average age of 3916 ± 7 Ma (95 % conf., MSWD = 1.1; P = 0.13) and a median average age of 3919 + 14/-12 Ma, both of which agree with the confidence interval obtained using the U-Pb system. These samples, dated by 40Ar/39Ar method, can be also viewed as representing the Imbrium impact. In total 36 out of 41 breccia samples from five landing sites can be interpreted to represent formation of the Imbrium basin, supporting the conclusion that Imbrium material was distributed widely across the near side of the Moon. Establishing temporal limits for the Imbrium impact allows discrimination of ten samples with Rb-Sr and 40Ar/39Ar ages about 50 Ma younger than 3922 ± 12 Ma. This group may represent a separate single impact on the Moon and needs to be investigated further to improve our understanding of lunar impact history.  相似文献   

16.
Mafic impact-melt breccias (IMB) from the Apollo landing sites—particularly Apollo 14, Apollo 15, Apollo 16, and Apollo 17—are abundant and form compositionally distinct groups. These groups exhibit a range of major-element compositions and incompatible-element enrichments. Although concentrations of incompatible elements span a significant range, inter-element ratios vary little and have been used in the past to infer a common KREEP component (KREEP = rich in potassium, rare-earth elements, phosphorus, and other alkali and high-field-strength elements). On the basis of an extensive, high-precision data set for melt-breccia groups from different Apollo landing sites, variations in trace-element signatures of the mafic impact-melt breccias reflect significant differences in KREEP components of source regions. These differences are consistent with variable enrichment or depletion of source regions in those trace elements that fractionated during the latest stages of residual-melt evolution and are more or less related to “lunar granite.” Compared to other sites, the source region of Apollo 14 impact melts had an excess of the elements that are concentrated in lunar granite, suggesting either than this source region was enriched in such a component (K-frac) or that it lost a corresponding mafic component (REEP-frac). Because these are impact-melt breccias formed in large (probably basin) impacts, the indicated geochemical separations must have occurred on a broad scale.

Variations in the incompatible-element concentrations of the IMB groups reported in this paper are used to calculate a revised KREEP incompatible-element composition. On the basis of several extremely enriched lunar samples that retain the incompatible elements in KREEP-like ratios, the KREEP composition is extended to a level of 300 ppm La, or about three times the concentration of high-potassium KREEP as estimated by Warren (1989).  相似文献   

17.
利用NASA行星数据系统提供Apollo计划登月点采样线路影像数据,通过与嫦娥二号CCD数据、印度M~3数据空间校正获得采样路线坐标。开展嫦娥二号CCD数据与印度M~3数据MAP(后验概率)融合并选择Apollo 15、Apollo 16-62231的LSCC测得的标准岩石双向反射率光谱与M~3、嫦娥二号进行交叉定标。本文采用月球岩石光谱谱型全特征分析方法,选取涵盖Apollo计划登月获取的36个基站主要岩性87种、285件岩石样品,利用校正后的M~3数据分析月球典型岩石各阶吸收反射特征,建立月球典型岩石标准遥感影像光谱库,此后应用Apollo 623个岩石样品进行对比得到很好结果,同时完成Apollo 16登月点周围领域岩性分布图,并讨论了研究区的岩石成因,Apollo 16区域形成于高地大撞击,在早期的研究中已经被用于划分月球年代,本文方法对于月球岩石类别研究与理解月球的岩浆演化具有重要的研究价值。  相似文献   

18.
Accurate estimates of global concentrations of Th, K, and FeO have an important bearing on understanding the bulk chemistry and geologic evolution of the Moon. We present empirical ground-truth calibrations (transformations) for Lunar Prospector gamma-ray spectrometer data (K and Th) and a modified algorithm for deriving FeO concentrations from Clementine spectral reflectance data that incorporates an adjustment for TiO2 content. The average composition of soil samples for individual landing sites is used as ground-truth for remotely sensed data. Among the Apollo and Luna sites, Apollo 12 and 14 provide controls for the incompatible-element-rich compositions, Apollo 16 and Luna 20 provide controls for the feldspathic and incompatible-element-poor compositions, and Apollo 11, 15, and 17, and Luna 16 and 24 provide controls for Fe-rich compositions. In addition to these Apollo and Luna sample data we include the composition of the feldspathic lunar meteorites as a proxy for the northern farside highlands to extend the range of the calibration points, thus providing an additional anorthositic end-member composition. These empirical ground-truth calibrations for Lunar Prospector Th and K provide self consistency between the existing derived data and lunar-sample data. Clementine spectral-reflectance data are used to construct a TiO2-sensitive FeO calibration that yields higher FeO concentrations in areas of high-Fe, low-Ti, mare-basalt-rich surfaces than previous FeO algorithms. The data set so derived is consistent with known sample compositions and regolith mixing relationships.  相似文献   

19.
Volcanic glasses from the Apollo 11, 14, 15, and 16 landing sites have been analyzed for major elements and Ni by electron microprobe. The 19 varieties of volcanic glass define two distinct chemical arrays that provide new insights into (a) the petrogenesis of mare basalts and (b) the structure of the deep lunar interior. A simple model is proposed whereby mare basaltic liquids may have been derived from two isolated, cumulate systems occurring at depths of ~300 km and ? 400 km. Each system was itself composed of two lithologic components (low-Ti vs high-Ti) that underwent hybridization, assimilation, or mixing to generate the large compositional range of magmas observed within each array. While the distribution of the two components within each system was locally heterogeneous, data indicate that the components themselves were chemically uniform on at least a regional scale. The surface-correlated volatiles associated with the lunar volcanic glasses seem to have come from some other reservoir within the Moon.The simplicity of the chemical relationships observed among the lunar volcanic glasses allow specific-predictions to be made. We believe that they should readily reveal any strengths or weaknesses of this new model.  相似文献   

20.
基于ArcGIS的月球虹湾地区数字地质图编制研究   总被引:2,自引:0,他引:2       下载免费PDF全文
虹湾幅月球数字地质图是中国首次编制的关于月球地质演化的地质图,应用的主要数据资料来源于"中国首次月球探测工程"嫦娥一号CCD影像数据、DEM数据,结合Clementine750nm影像数据,主要月坑的高分辨率图片,同时结合前人的研究成果,如主要矿物元素含量分布图、多波段反射率特征分布图等编制完成。所有的数据处理应用的是ArcMap平台,同时结合使用了MapGIS软件和Photoshop软件,数据模型采用Geodatabase地理数据模型。详细介绍了基于ArcGIS平台编制月球数字地质图的工作流程,编制方法及依据、编制规则及数据库的建立等,为今后开展月球数字地质图的编制积累了经验。  相似文献   

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