月球风暴洋区域玄武岩厚度反演研究
发布时间：2019-05-06 21:36
【摘要】：风暴洋是月球最大的月海,其表面构造丰富,玄武岩年代跨度广,既有古老的高钛玄武岩,也有月球上最新形成的中钛玄武岩。研究风暴洋区域玄武岩厚度,了解月球浅表层结构特征,对于推断月球岩浆演化历史,探索月球的热演化过程具有重要意义。鉴于以往的风暴洋区域玄武岩厚度研究中,所使用的观测数据的空间分辨率较低,受月球表面曲率、表面起伏影响较大,只注重剖面式月海分层结构研究,本研究结合风暴洋区域地势特征,基于日本SELENE探月卫星搭载的月球雷达探测仪LRS(Lunar Radar Sounder)获取的高分辨率、全月覆盖的数据,依据雷达成像原理,在真实的雷达子波的基础上正演模拟了月球次表层结构特征;然后,通过双层介质模型及脉冲压缩原理,介绍了LRS数据的处理过程,得到了风暴洋区域次表层结构剖面图,分析了介电常数和接收器孔径大小等参数对LRS数据分辨率的影响。结果显示,在LRS数据成像过程中,玄武岩相对介电常数和接收器孔径大小是两个重要参数。图像分辨率与接收器孔径大小呈正相关,当孔径大小由5km增大到40km时,图像分辨率得到了明显改善,可以获得较高分辨率的月球次表层截面图;根据对模拟误差的估计,玄武岩相对介电常数选取为6.25时,反演误差介于-0.2到0.2之间,保证了玄武岩厚度的反演精度。同时,本文根据次表层回波图像特征,对风暴洋区域大面积范围内的玄武岩厚度进行了反演研究,绘制了玄武岩等厚图,并结合该区域成分信息详细描述了风暴洋区域月海玄武岩分布特征,深入分析了成分因素对玄武岩厚度及分布特征的影响,推断了该区域玄武岩岩浆演化过程。研究结果表明,风暴洋覆盖着平均厚度约为65m的玄武岩,在大型撞击坑周围区域玄武岩厚度可达108m(41°W,30°N),其他区域玄武岩厚度最小约为27m(49°W,8°N)。对比风暴洋区域的成分分布特征可知,LRS探测器探测到的次表层分界面的位置深度与月球表层中的铁钛含量分布相关。在Fe O和Ti O2含量相对较低的区域,探测得到的玄武岩岩层厚度相对较大;而在Fe O和Ti O2含量相对较高的区域,探测得到的玄武岩厚度相对较小,这是由于过高的Fe O、Ti O2含量影响了雷达探测器对介电常数差异的敏感性。本研究结合玄武岩厚度和成分信息深入研究了风暴洋区域月海玄武岩的分布规律,详细分析了不同因素对月海玄武岩厚度及分布的影响,为推断月球岩浆演化过程提供了重要的月球地质、地球物理信息。本文改进了月球次表层结构特征探究的方法,为研究月球次表层月岩的分布特征提供了新的思路,为推断月球的热演化历史探寻了新的途径。
[Abstract]:The storm ocean is the largest lunar sea on the moon. Its surface is rich in structure and its basalts span a wide range of ages. There are both ancient high titanium basalts and newly formed middle titanium basalts on the moon. It is of great significance to study the thickness of basalts in the storm ocean region and to understand the structural characteristics of the shallow surface of the moon. In view of the previous studies on the thickness of basalts in the storm ocean region, the spatial resolution of the observed data is low, which is greatly influenced by the curvature of the lunar surface and the surface fluctuation, and only pays attention to the study of the sectional delamination structure of the lunar sea. In this study, combined with the features of the storm ocean region, based on the high-resolution, full-month coverage data obtained by the lunar radar sounding instrument LRS (Lunar Radar Sounder) carried by the Japanese SELENE lunar exploration satellite, and according to the radar imaging principle, On the basis of the real radar wavelet, the structural characteristics of the subsurface layer of the moon are simulated forward. Then, through the double-layer dielectric model and pulse compression principle, the processing process of LRS data is introduced, and the subsurface structure profile of storm ocean region is obtained. The effects of dielectric constant and receiver aperture size on the resolution of LRS data are analyzed. The results show that the relative permittivity of basalt and the size of receiver aperture are two important parameters in LRS imaging. The resolution of the image is positively correlated with the aperture size of the receiver. When the aperture size is increased from 5km to 40km, the resolution of the image is improved obviously, and the subsurface section of the moon with higher resolution can be obtained. According to the estimation of simulation error, when the relative dielectric constant of basalt is 6.25, the inversion error is between-0.2 and 0.2, which ensures the accuracy of basalt thickness inversion. At the same time, according to the characteristics of subsurface echo images, the thickness of basalts in a large area of the storm ocean is inversed and the basalt isothickness map is plotted. The distribution characteristics of monthly and sea basalts in the storm ocean region are described in detail, and the influence of composition factors on the thickness and distribution characteristics of basalts is analyzed. The evolution process of basalt magma in this area is inferred. The results show that the storm ocean is covered with basalt with an average thickness of about 65 m. The basalt thickness can reach 108 m (41 掳W, 30 掳N) in the area around the large impact crater, and the minimum basalt thickness in other areas is about 27 m (49 掳W, 8 掳N). Comparing the characteristics of composition distribution in the storm ocean region, we can see that the depth of the subsurface interface detected by the LRS detector is related to the distribution of iron and titanium content in the surface of the moon. In the area where Fe O and Ti O 2 contents are relatively low, the thickness of basalt strata detected is relatively large. In the region where Fe O and Ti O 2 contents are relatively high, the thickness of basalts detected is relatively small, which is due to the excessive Fe O, and TIO 2 content affects the sensitivity of radar detectors to the difference of dielectric constants. Based on the information of basalt thickness and composition, the distribution rule of monthly sea basalt in storm ocean area is studied in this paper, and the influence of different factors on the thickness and distribution of monthly sea basalt is analyzed in detail. It provides important information of lunar geology and geophysics for inferring the evolution of lunar magma. This paper improves the method of exploring the structural characteristics of the lunar subsurface, provides a new way to study the distribution characteristics of the lunar subsurface rocks, and explores a new way to deduce the history of the moon's thermal evolution.
【学位授予单位】：吉林大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：P184.5
本文编号：2470512
[Abstract]:The storm ocean is the largest lunar sea on the moon. Its surface is rich in structure and its basalts span a wide range of ages. There are both ancient high titanium basalts and newly formed middle titanium basalts on the moon. It is of great significance to study the thickness of basalts in the storm ocean region and to understand the structural characteristics of the shallow surface of the moon. In view of the previous studies on the thickness of basalts in the storm ocean region, the spatial resolution of the observed data is low, which is greatly influenced by the curvature of the lunar surface and the surface fluctuation, and only pays attention to the study of the sectional delamination structure of the lunar sea. In this study, combined with the features of the storm ocean region, based on the high-resolution, full-month coverage data obtained by the lunar radar sounding instrument LRS (Lunar Radar Sounder) carried by the Japanese SELENE lunar exploration satellite, and according to the radar imaging principle, On the basis of the real radar wavelet, the structural characteristics of the subsurface layer of the moon are simulated forward. Then, through the double-layer dielectric model and pulse compression principle, the processing process of LRS data is introduced, and the subsurface structure profile of storm ocean region is obtained. The effects of dielectric constant and receiver aperture size on the resolution of LRS data are analyzed. The results show that the relative permittivity of basalt and the size of receiver aperture are two important parameters in LRS imaging. The resolution of the image is positively correlated with the aperture size of the receiver. When the aperture size is increased from 5km to 40km, the resolution of the image is improved obviously, and the subsurface section of the moon with higher resolution can be obtained. According to the estimation of simulation error, when the relative dielectric constant of basalt is 6.25, the inversion error is between-0.2 and 0.2, which ensures the accuracy of basalt thickness inversion. At the same time, according to the characteristics of subsurface echo images, the thickness of basalts in a large area of the storm ocean is inversed and the basalt isothickness map is plotted. The distribution characteristics of monthly and sea basalts in the storm ocean region are described in detail, and the influence of composition factors on the thickness and distribution characteristics of basalts is analyzed. The evolution process of basalt magma in this area is inferred. The results show that the storm ocean is covered with basalt with an average thickness of about 65 m. The basalt thickness can reach 108 m (41 掳W, 30 掳N) in the area around the large impact crater, and the minimum basalt thickness in other areas is about 27 m (49 掳W, 8 掳N). Comparing the characteristics of composition distribution in the storm ocean region, we can see that the depth of the subsurface interface detected by the LRS detector is related to the distribution of iron and titanium content in the surface of the moon. In the area where Fe O and Ti O 2 contents are relatively low, the thickness of basalt strata detected is relatively large. In the region where Fe O and Ti O 2 contents are relatively high, the thickness of basalts detected is relatively small, which is due to the excessive Fe O, and TIO 2 content affects the sensitivity of radar detectors to the difference of dielectric constants. Based on the information of basalt thickness and composition, the distribution rule of monthly sea basalt in storm ocean area is studied in this paper, and the influence of different factors on the thickness and distribution of monthly sea basalt is analyzed in detail. It provides important information of lunar geology and geophysics for inferring the evolution of lunar magma. This paper improves the method of exploring the structural characteristics of the lunar subsurface, provides a new way to study the distribution characteristics of the lunar subsurface rocks, and explores a new way to deduce the history of the moon's thermal evolution.
【学位授予单位】：吉林大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：P184.5
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