scholarly journals Density Structure of the Von Kármán Crater in the Northwestern South Pole-Aitken Basin: Initial Subsurface Interpretation of the Chang’E-4 Landing Site Region

Sensors ◽  
2019 ◽  
Vol 19 (20) ◽  
pp. 4445
Author(s):  
Chikondi Chisenga ◽  
Jianguo Yan ◽  
Jiannan Zhao ◽  
Qingyun Deng ◽  
Jean-Pierre Barriot
Keyword(s):  
Gravity Data ◽  
Landing Site ◽  
Gravity Inversion ◽  
Inversion Method ◽  
South Pole ◽  
Impact Cratering ◽  
Near Surface ◽  
Von Karman ◽  
Multiple Impact ◽  
Von Kármán

The Von Kármán Crater, within the South Pole-Aitken (SPA) Basin, is the landing site of China’s Chang’E-4 mission. To complement the in situ exploration mission and provide initial subsurface interpretation, we applied a 3D density inversion using the Gravity Recovery and Interior Laboratory (GRAIL) gravity data. We constrain our inversion method using known geological and geophysical lunar parameters to reduce the non-uniqueness associated with gravity inversion. The 3D density models reveal vertical and lateral density variations, 2600–3200 kg/m3, assigned to the changing porosity beneath the Von Kármán Crater. We also identify two mass excess anomalies in the crust with a steep density contrast of 150 kg/m3, which were suggested to have been caused by multiple impact cratering. The anomalies from recovered near surface density models, together with the gravity derivative maps extending to the lower crust, are consistent with surface geological manifestation of excavated mantle materials from remote sensing studies. Therefore, we suggest that the density distribution of the Von Kármán Crater indicates multiple episodes of impact cratering that resulted in formation and destruction of ancient craters, with crustal reworking and excavation of mantle materials.

scholarly journals Geological Characteristics of Von Kármán Crater, Northwestern South Pole-Aitken Basin: Chang'E-4 Landing Site Region

2018 ◽  
Vol 123 (7) ◽  
pp. 1684-1700 ◽  
Author(s):  
Jun Huang ◽  
Zhiyong Xiao ◽  
Jessica Flahaut ◽  
Mélissa Martinot ◽  
James Head ◽  
...  
Keyword(s):  
Landing Site ◽  
South Pole ◽  
Geological Characteristics ◽  
Von Karman ◽  
Von Kármán

Composition, mineralogy and chronology of mare basalts and non-mare materials in Von Kármán crater: Landing site of the Chang’E−4 mission

2019 ◽  
Vol 179 ◽  
pp. 104741 ◽  
Author(s):  
Zongcheng Ling ◽  
Le Qiao ◽  
Changqing Liu ◽  
Haijun Cao ◽  
Xiangyu Bi ◽  
...  
Keyword(s):  
Landing Site ◽  
Von Karman ◽  
Von Kármán ◽  
Mare Basalts

Three‐dimensional gravity inversion using simulated annealing: Constraints on the diapiric roots of allochthonous salt structures

Geophysics ◽  
2001 ◽  
Vol 66 (5) ◽  
pp. 1438-1449 ◽  
Author(s):  
Seiichi Nagihara ◽  
Stuart A. Hall
Keyword(s):  
Simulated Annealing ◽  
Gulf Of Mexico ◽  
Gravity Data ◽  
A Priori ◽  
Gravity Inversion ◽  
Inversion Method ◽  
A Priori Information ◽  
Final Density ◽  
Smoothing Effects ◽  
Priori Information

In the northern continental slope of the Gulf of Mexico, large oil and gas reservoirs are often found beneath sheetlike, allochthonous salt structures that are laterally extensive. Some of these salt structures retain their diapiric feeders or roots beneath them. These hidden roots are difficult to image seismically. In this study, we develop a method to locate and constrain the geometry of such roots through 3‐D inverse modeling of the gravity anomalies observed over the salt structures. This inversion method utilizes a priori information such as the upper surface topography of the salt, which can be delineated by a limited coverage of 2‐D seismic data; the sediment compaction curve in the region; and the continuity of the salt body. The inversion computation is based on the simulated annealing (SA) global optimization algorithm. The SA‐based gravity inversion has some advantages over the approach based on damped least‐squares inversion. It is computationally efficient, can solve underdetermined inverse problems, can more easily implement complex a priori information, and does not introduce smoothing effects in the final density structure model. We test this inversion method using synthetic gravity data for a type of salt geometry that is common among the allochthonous salt structures in the Gulf of Mexico and show that it is highly effective in constraining the diapiric root. We also show that carrying out multiple inversion runs helps reduce the uncertainty in the final density model.

scholarly journals 3D Gravity Inversion with Correlation Image in Space Domain and Application to the Northern Sinai Peninsula

2019 ◽  
Vol 1 (2) ◽  
Author(s):  
Xu Zhang ◽  
Peng Yu ◽  
Jian Wang
Keyword(s):  
Density Distribution ◽  
Gravity Data ◽  
Descent Method ◽  
Steepest Descent Method ◽  
Gravity Inversion ◽  
Inversion Method ◽  
Sinai Peninsula ◽  
Space Domain ◽  
Correlation Image ◽  
Starting Model

We present a 3D inversion method to recover density distribution from gravity data in space domain. Our method firstly employs 3D correlation image of the vertical gradient of gravity data as a starting model to generate a higher resolution image for inversion. The 3D density distribution is then obtained by inverting the correlation image of gravity data to fit the observed data based on classical inversion method of the steepest descent method. We also perform the effective equivalent storage and subdomain techniques in the starting model calculation, the forward modeling and the inversion procedures, which allow fast computation in space domain with reducing memory consumption but maintaining accuracy. The efficiency and stability of our method is demonstrated on two sets of synthetic data and one set of the Northern Sinai Peninsula gravity data. The inverted 3D density distributions show that high density bodies beneath Risan Aniza and low density bodies exist to the southeast of Risan Aniza at depths between 1~10 and 20 km, which may be originated from hot anomalies in the lower crust. The results show that our inversion method is useful for 3D quantitative interpretation.

Gravity data as a tool for detecting faults: In-depth enhancement of subtle Almada’s basement faults, Brazil

Geophysics ◽  
2007 ◽  
Vol 72 (3) ◽  
pp. B59-B68 ◽  
Author(s):  
Valeria C. Barbosa ◽  
Paulo T. Menezes ◽  
João B. Silva
Keyword(s):  
Gravity Data ◽  
Synthetic Data ◽  
Normal Fault ◽  
Northeastern Brazil ◽  
Normal Faults ◽  
Gravity Inversion ◽  
Inversion Method ◽  
Basement Faults ◽  
Depth Enhancement ◽  
Fault Displacement

We demonstrate the potential of gravity data to detect and to locate in-depth subtle normal faults in the basement relief of a sedimentary basin. This demonstration is accomplished by inverting the gravity data with the constraint that the estimated basement relief presents local abrupt faults and is smooth elsewhere. We inverted the gravity data from the onshore Almada Basin in northeastern Brazil, and we mapped several normal faults whose locations and plane geometries were already known from seismic imaging. The inversion method delineated well both the discontinuities with small or large slips and a sequence of step faults. Using synthetic data, we performed a systematic search of normal fault slips versus fault displacement depths to map the fault-detectable region in this space. This mapping helps to assess the ability of gravity inversion to detect normal faults. Mapping shows that normal faults with small [Formula: see text], medium (about [Formula: see text]), and large (about [Formula: see text]) vertical slips can be detected if the maximum midpoint depths of the fault planes are smaller than 1.8, 3.8, and [Formula: see text], respectively.

Topographic and Geomorphological Mapping and Analysis of the Chang'E-4 Landing Site on the Far Side of the Moon

2020 ◽  
Vol 86 (4) ◽  
pp. 247-258 ◽  
Author(s):  
Bo Wu ◽  
Fei Li ◽  
Han Hu ◽  
Yang Zhao ◽  
Yiran Wang ◽  
...  
Keyword(s):  
Landing Site ◽  
Joint Analysis ◽  
The Sun ◽  
The Moon ◽  
Soft Landing ◽  
Geomorphological Mapping ◽  
Von Karman ◽  
Lunar Reconnaissance Orbiter ◽  
Integrated Processing ◽  
Von Kármán

The Chinese lunar probe Chang'E-4 successfully landed in the Von Kármán crater on the far side of the Moon. This paper presents the topographic and geomorphological mapping and their joint analysis for selecting the Chang'E-4 landing site in the Von Kármán crater. A digital topographic model (<small>DTM</small>) of the Von Kármán crater, with a spatial resolution of 30 m, was generated through the integrated processing of Chang'E-2 images (7 m/pixel) and Lunar Reconnaissance Orbiter (<small>LRO</small>) Laser Altimeter (<small>LOLA</small>) data. Slope maps were derived from the <small>DTM</small>. Terrain occlusions to both the Sun and the relay satellite were studied. Craters with diameters ≥ 70 m were detected to generate a crater density map. Rocks with diameters ≥ 2 m were also extracted to generate a rock abundance map using an <small>LRO</small> narrow angle camera (<small>NAC</small>) image mosaic. The joint topographic and geomorphological analysis identified three subregions for landing. One of them, recommended as the highest-priority landing site, was the one in which Chang'E-4 eventually landed. After the successful landing of Chang'E-4, we immediately determined the precise location of the lander by the integrated processing of orbiter, descent and ground images. We also conducted a detailed analysis around the landing location. The results revealed that the Chang'E-4 lander has excellent visibility to the Sun and relay satellite; the lander is on a slope of about 4.5° towards the southwest, and the rock abundance around the landing location is almost 0. The developed methods and results can benefit future soft-landing missions to the Moon and other celestial bodies.

Integration of geophysical constraints for multilayer geometry refinements in 2.5D gravity inversion

Geophysics ◽  
2016 ◽  
Vol 81 (5) ◽  
pp. G95-G106 ◽  
Author(s):  
Jian Xing ◽  
Tianyao Hao ◽  
Ya Xu ◽  
Zhiwei Li
Keyword(s):  
Gravity Data ◽  
Inequality Constraints ◽  
Real Data ◽  
Gravity Inversion ◽  
Inversion Method ◽  
Sharp Condition ◽  
Estimated Parameters ◽  
Multiple Interfaces ◽  
Variation Function ◽  
Different Depths

We have explored the feasibility of estimating depths of multiple interfaces from gravity data. The strata are simulated by an aggregate of 3D rectangular prisms whose bottom depths are parameters to be estimated. In the inversion process, we have integrated geophysical constraints including the borehole information and the sharp condition described by the total variation function. The iterative residual function is also introduced to adjust the weighting of the estimated parameters so that layers of different depths have nearly equal likelihood for deviation. The inversion is processed by minimizing the Tikhonov parametric functional by the reweighted regularized conjugate gradient method. Inequality constraints are adopted to deal with the coupling of the interfaces. Synthetic tests show that such integration is conducive to restoring the multilayer depth distribution. Real data applications in Mariana confirm that the inversion method is effective in complex geologic settings in practice. We have also evaluated several issues that specifically deserve attention for obtaining satisfactory results in multilayer gravity inversion.

scholarly journals POTENTIAL GEOLOGIC ISSUES OF VON KÁRMÁN CRATER REVEALED BY MULTISOURCE REMOTE SENSING DATA

2019 ◽  
Vol XLII-2/W13 ◽  
pp. 1425-1430 ◽  
Author(s):  
Z. G. Meng ◽  
H. H. Wang ◽  
S. B. Chen ◽  
J. S. Ping ◽  
Q. Huang ◽  
...  
Keyword(s):  
Remote Sensing Data ◽  
Landing Site ◽  
Original Material ◽  
Crater Floor ◽  
Depth Layer ◽  
Von Karman ◽  
Warm Anomaly ◽  
Cold Anomaly ◽  
Rich Material ◽  
Von Kármán

<p><strong>Abstract.</strong> Von Kármán crater is the landing area for CE-4 mission, which provides a chance to further study the evolution of South-Pole Aitken basin. In this paper, the topography, composition, temperature and deep structures of Von Kármán crater are systematically studied with LRO LOLA data, Clementine UV-VIS data, CE-2 CELMS data, and GRAIL data. Several potential geologic issues are postulated as follows: (1) There exists a difference for the southern and northern parts of the crater floor in topography. The surface topography is influenced by Leibnitz and Finsen events. (2) There exists an FTA-rich material in depth layer of the crater floor, and the later bombardments exposed the original material in the crater floor. And the material in depth is homogeneous. (3) The composition apparently changes with depth, and there exist a warm anomaly in the northern part of the crater floor and a cold anomaly in the southern part. (4) A large amount of magma has been uplifted after Von Kármán M impact event, and the crust has been melted several times and condensed into dense basalt layer. Generally, this is a good place to measure the material from the original SPA basin and the material from the depth layer of the Moon for the CE-4 landing site.</p>

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