As one of the prominent landforms in the Zhurong landing region,mesas are geological features with flat tops and steep marginal cliffs.The mesas are widely distributed along the dichotomy boundary.There are various in...As one of the prominent landforms in the Zhurong landing region,mesas are geological features with flat tops and steep marginal cliffs.The mesas are widely distributed along the dichotomy boundary.There are various interpreted origins proposed for the mesas,such as the erosion of sedimentary layers,tuyas eruptions,or surface collapse due to the catastrophic release of groundwater.We investigate the detailed morphological characteristics of the mesas on the Late Hesperian Lowland unit within the Utopia Planitia.We observe morphological evidence for both the ice-bearing interior mesas and the sedimentary origin,including(1)small pits on the crater wall and mesa cliff formed by the release of volatiles like ice;(2)lobate flows at the base of mesas formed by the melting of subsurface ice;(3)layered mesas indicating sedimentary origin;(4)grooves on the top surface of mesas formed by the volumetric compaction of sedimentary deposits.The results indicate that the mesas in the study area are formed by the erosion of sedimentary layers and representative of the Noachian oceanic sediments.We propose an evolutionary model for the mesas.This study will provide some insights into future research of ancient ocean hypothesis of Mars and interesting targets for the exploration of the Zhurong rover.展开更多
The Beta-Atla-Themis(BAT)region on Venus is characterized by large volcanic rises,major rift zones(chasmata),radiating,linear,and circumferential grabenfissure systems,and coronae.Its most prominent features
1 A possible ancient shoreline has been found in the region of Mars explored by the Chinese rover,Zhurong,providing further evidence that an ocean may once have covered a vast area of the lowlands in the planet's ...1 A possible ancient shoreline has been found in the region of Mars explored by the Chinese rover,Zhurong,providing further evidence that an ocean may once have covered a vast area of the lowlands in the planet's northern part.2 The rover landed in southern Utopia Planitia in May 2021 and remained active for almost a year.Researchers studying data from the rover have found clues of an ancient ocean or liquid water as recently as 400,000 years ago.展开更多
The Elysium Planitia,located in the transition zone between the northern and southern hemispheres,is one of the key areas for studying the stratigraphic structure and geological history of Mars.Previous studies have s...The Elysium Planitia,located in the transition zone between the northern and southern hemispheres,is one of the key areas for studying the stratigraphic structure and geological history of Mars.Previous studies have shown that this plain has undergone complex surface modification processes including fluvial and volcanic processes,and systematic progress has been made in the study of macro-geological processes.However,there are relatively few studies on the regional structure of the plain,which restricts our understanding of the regional geological processes.A buried impact crater in the central part of the Elysium Planitia could have recorded the surface modification process since the formation of the impact crater,however,it is difficult to distinguish the subsurface stratigraphy due to the weak orbital radar reflection signal.In this study,we denoised Shallow Radar data and obtained a radargram with clear subsurface reflectors.We estimated the permittivity of subsurface materials via a multilayer reflection model.The results show that two subsurface reflectors divide the structure of the buried impact crater into three layers(overlying layer,underlying layer,and bottom layer).The shallow subsurface reflector covers almost the whole impact crater,while the deep subsurface reflector covers only the southwest part of the impact crater.Combining the permittivity inversion results with the geological background of lava activity in the Elysium Planitia area,we argue that the overlying layer may be a mixture of regolith and lava flow with low density,while the underlying layer and bottom layer are dense lava flows.The reflector between the underlying layer and bottom layer is probably a thin deposit derived from weathering between two lava activities,and its possible formation mechanism is as follows:the crater rim and peripheral ejecta has undergone relatively strong wind erosion and the eroded material was transport to the southwestern part of the impact crater,forming continuous thin deposits,between the emplacements of two lava flows.This is consistent with the wind erosion environment prevailing at low latitudes in the Late Amazonian of Mars.This study uses processed orbital radar data,dielectric property inversion,and geological structure interpretation of regional buried impact craters as a local example to demonstrate how radar data can be used to understand regional depositional processes,and it serves as a reference for studying the geological history of similar regional structures on Mars.展开更多
China’s first Mars exploration mission,Tianwen-1,successfully landed in southern Utopia Planitia on Mars on May 15,2021.This work presents a detailed investigation of the geologic context of the landing area surface ...China’s first Mars exploration mission,Tianwen-1,successfully landed in southern Utopia Planitia on Mars on May 15,2021.This work presents a detailed investigation of the geologic context of the landing area surface for this mission based on orbital remotesensing data.We constructed a geomorphologic map for the Tianwen-1 landing area.Results of our detailed geomorphologic map show several major landforms within the landing area,including rampart craters,mesas,troughs,cones,and ridges.Analysis of materials on the landing area surface indicates that most of the landing area is covered by Martian dust.Transverse aeolian ridges are widely distributed within the landing area,indicating the surface contexts were(and still are)modified by regional winds.In addition,a crater counting analysis indicates the landing area has an absolute model age of~3.3 Ga and that a later resurfacing event occurred at~1.6 Ga.Finally,we outline four formational scenarios to test the formation mechanisms for the geomorphologic features on the landing area surface.The most likely interpretation to explain the existence of the observed surface features can be summarized as follows:A thermal influence may have played an important role in the formation of the surface geomorphologic features;thus,igneous-related processes may have occurred in the landing area.Water ice may also have been involved in the construction of the primordial surface configuration.Subsequent resurfacing events and aeolian processes buried and modified the primordial surface.展开更多
基金supported by the Strategic Priority Research Program of the Chinese Academy of Sciences(No.XDB 41000000)the National Natural Science Foundation of China(Nos.42273041,41830214)the Preresearch Project on Civil Aerospace Technologies of CNSA(No.D020101)。
文摘As one of the prominent landforms in the Zhurong landing region,mesas are geological features with flat tops and steep marginal cliffs.The mesas are widely distributed along the dichotomy boundary.There are various interpreted origins proposed for the mesas,such as the erosion of sedimentary layers,tuyas eruptions,or surface collapse due to the catastrophic release of groundwater.We investigate the detailed morphological characteristics of the mesas on the Late Hesperian Lowland unit within the Utopia Planitia.We observe morphological evidence for both the ice-bearing interior mesas and the sedimentary origin,including(1)small pits on the crater wall and mesa cliff formed by the release of volatiles like ice;(2)lobate flows at the base of mesas formed by the melting of subsurface ice;(3)layered mesas indicating sedimentary origin;(4)grooves on the top surface of mesas formed by the volumetric compaction of sedimentary deposits.The results indicate that the mesas in the study area are formed by the erosion of sedimentary layers and representative of the Noachian oceanic sediments.We propose an evolutionary model for the mesas.This study will provide some insights into future research of ancient ocean hypothesis of Mars and interesting targets for the exploration of the Zhurong rover.
文摘The Beta-Atla-Themis(BAT)region on Venus is characterized by large volcanic rises,major rift zones(chasmata),radiating,linear,and circumferential grabenfissure systems,and coronae.Its most prominent features
文摘1 A possible ancient shoreline has been found in the region of Mars explored by the Chinese rover,Zhurong,providing further evidence that an ocean may once have covered a vast area of the lowlands in the planet's northern part.2 The rover landed in southern Utopia Planitia in May 2021 and remained active for almost a year.Researchers studying data from the rover have found clues of an ancient ocean or liquid water as recently as 400,000 years ago.
基金supported by the National Natural Science Foundation of China(Grant No.41941002)the Key Research Program of the Institute of Geology and Geophysics,CAS(Grant No.IGGCAS-202203)+1 种基金the Key Research Program of the Chinese Academy of Sciences(Grant No.ZDBS-SSW-TLC001)the Open Research Program of the International Research Center of Big Data for Sustainable Development Goals(Grant No.CBAS2022GSP06)。
文摘The Elysium Planitia,located in the transition zone between the northern and southern hemispheres,is one of the key areas for studying the stratigraphic structure and geological history of Mars.Previous studies have shown that this plain has undergone complex surface modification processes including fluvial and volcanic processes,and systematic progress has been made in the study of macro-geological processes.However,there are relatively few studies on the regional structure of the plain,which restricts our understanding of the regional geological processes.A buried impact crater in the central part of the Elysium Planitia could have recorded the surface modification process since the formation of the impact crater,however,it is difficult to distinguish the subsurface stratigraphy due to the weak orbital radar reflection signal.In this study,we denoised Shallow Radar data and obtained a radargram with clear subsurface reflectors.We estimated the permittivity of subsurface materials via a multilayer reflection model.The results show that two subsurface reflectors divide the structure of the buried impact crater into three layers(overlying layer,underlying layer,and bottom layer).The shallow subsurface reflector covers almost the whole impact crater,while the deep subsurface reflector covers only the southwest part of the impact crater.Combining the permittivity inversion results with the geological background of lava activity in the Elysium Planitia area,we argue that the overlying layer may be a mixture of regolith and lava flow with low density,while the underlying layer and bottom layer are dense lava flows.The reflector between the underlying layer and bottom layer is probably a thin deposit derived from weathering between two lava activities,and its possible formation mechanism is as follows:the crater rim and peripheral ejecta has undergone relatively strong wind erosion and the eroded material was transport to the southwestern part of the impact crater,forming continuous thin deposits,between the emplacements of two lava flows.This is consistent with the wind erosion environment prevailing at low latitudes in the Late Amazonian of Mars.This study uses processed orbital radar data,dielectric property inversion,and geological structure interpretation of regional buried impact craters as a local example to demonstrate how radar data can be used to understand regional depositional processes,and it serves as a reference for studying the geological history of similar regional structures on Mars.
基金supported by the Key Research Program of the Chinese Academy of Sciences(Grant No.ZDBS-SSW-TLC001)the National Natural Science Foundation(Grant No.11803056).
文摘China’s first Mars exploration mission,Tianwen-1,successfully landed in southern Utopia Planitia on Mars on May 15,2021.This work presents a detailed investigation of the geologic context of the landing area surface for this mission based on orbital remotesensing data.We constructed a geomorphologic map for the Tianwen-1 landing area.Results of our detailed geomorphologic map show several major landforms within the landing area,including rampart craters,mesas,troughs,cones,and ridges.Analysis of materials on the landing area surface indicates that most of the landing area is covered by Martian dust.Transverse aeolian ridges are widely distributed within the landing area,indicating the surface contexts were(and still are)modified by regional winds.In addition,a crater counting analysis indicates the landing area has an absolute model age of~3.3 Ga and that a later resurfacing event occurred at~1.6 Ga.Finally,we outline four formational scenarios to test the formation mechanisms for the geomorphologic features on the landing area surface.The most likely interpretation to explain the existence of the observed surface features can be summarized as follows:A thermal influence may have played an important role in the formation of the surface geomorphologic features;thus,igneous-related processes may have occurred in the landing area.Water ice may also have been involved in the construction of the primordial surface configuration.Subsequent resurfacing events and aeolian processes buried and modified the primordial surface.
