月球風暴洋區(qū)域玄武巖厚度反演研究
發(fā)布時間：2019-05-06 21:36
【摘要】：風暴洋是月球最大的月海,其表面構造豐富,玄武巖年代跨度廣,既有古老的高鈦玄武巖,也有月球上最新形成的中鈦玄武巖。研究風暴洋區(qū)域玄武巖厚度,了解月球淺表層結構特征,對于推斷月球巖漿演化歷史,探索月球的熱演化過程具有重要意義。鑒于以往的風暴洋區(qū)域玄武巖厚度研究中,所使用的觀測數(shù)據(jù)的空間分辨率較低,受月球表面曲率、表面起伏影響較大,只注重剖面式月海分層結構研究,本研究結合風暴洋區(qū)域地勢特征,基于日本SELENE探月衛(wèi)星搭載的月球雷達探測儀LRS(Lunar Radar Sounder)獲取的高分辨率、全月覆蓋的數(shù)據(jù),依據(jù)雷達成像原理,在真實的雷達子波的基礎上正演模擬了月球次表層結構特征;然后,通過雙層介質模型及脈沖壓縮原理,介紹了LRS數(shù)據(jù)的處理過程,得到了風暴洋區(qū)域次表層結構剖面圖,分析了介電常數(shù)和接收器孔徑大小等參數(shù)對LRS數(shù)據(jù)分辨率的影響。結果顯示,在LRS數(shù)據(jù)成像過程中,玄武巖相對介電常數(shù)和接收器孔徑大小是兩個重要參數(shù)。圖像分辨率與接收器孔徑大小呈正相關,當孔徑大小由5km增大到40km時,圖像分辨率得到了明顯改善,可以獲得較高分辨率的月球次表層截面圖;根據(jù)對模擬誤差的估計,玄武巖相對介電常數(shù)選取為6.25時,反演誤差介于-0.2到0.2之間,保證了玄武巖厚度的反演精度。同時,本文根據(jù)次表層回波圖像特征,對風暴洋區(qū)域大面積范圍內的玄武巖厚度進行了反演研究,繪制了玄武巖等厚圖,并結合該區(qū)域成分信息詳細描述了風暴洋區(qū)域月海玄武巖分布特征,深入分析了成分因素對玄武巖厚度及分布特征的影響,推斷了該區(qū)域玄武巖巖漿演化過程。研究結果表明,風暴洋覆蓋著平均厚度約為65m的玄武巖,在大型撞擊坑周圍區(qū)域玄武巖厚度可達108m(41°W,30°N),其他區(qū)域玄武巖厚度最小約為27m(49°W,8°N)。對比風暴洋區(qū)域的成分分布特征可知,LRS探測器探測到的次表層分界面的位置深度與月球表層中的鐵鈦含量分布相關。在Fe O和Ti O2含量相對較低的區(qū)域,探測得到的玄武巖巖層厚度相對較大;而在Fe O和Ti O2含量相對較高的區(qū)域,探測得到的玄武巖厚度相對較小,這是由于過高的Fe O、Ti O2含量影響了雷達探測器對介電常數(shù)差異的敏感性。本研究結合玄武巖厚度和成分信息深入研究了風暴洋區(qū)域月海玄武巖的分布規(guī)律,詳細分析了不同因素對月海玄武巖厚度及分布的影響,為推斷月球巖漿演化過程提供了重要的月球地質、地球物理信息。本文改進了月球次表層結構特征探究的方法,為研究月球次表層月巖的分布特征提供了新的思路,為推斷月球的熱演化歷史探尋了新的途徑。
[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 擄W, 30 擄N) in the area around the large impact crater, and the minimum basalt thickness in other areas is about 27 m (49 擄W, 8 擄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.
【學位授予單位】：吉林大學
【學位級別】：碩士
【學位授予年份】：2016
【分類號】：P184.5
本文編號：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 擄W, 30 擄N) in the area around the large impact crater, and the minimum basalt thickness in other areas is about 27 m (49 擄W, 8 擄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.
【學位授予單位】：吉林大學
【學位級別】：碩士
【學位授予年份】：2016
【分類號】：P184.5
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