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Mineralogical evidence of water activity in the northern lowlands of Mars based on inflight-calibrated spectra from the Zhurong rover

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Science China Earth Sciences 2023年第11期66卷 2463-2472页

作者： Honglei LIN Yangting LIN Yong WEI Sheng GOU Chi ZHANG Renhao RUAN Yongxin PAN key laboratory of Earth and Planetary Physics Institute of Geology and GeophysicsChinese Academy of SciencesBeijing 100029China

Hydrated minerals provide direct indications of the early Martian water environment. The various clay minerals and evaporite salts found to date are mainly exposed in the ancient southern highlands of Mars. While it is believed that the area of the northern lowlands could have hosted a global ocean in the past, its surface is covered with a layer of spectrally nonabsorbing materials, and orbital hyperspectral remote sensing has found only sparse evidence for the presence of water. China's first Mars exploration mission, Tianwen-1, landed in the putative ancient shoreline zone of the northern lowlands of Mars. Its rover,Zhurong, conducted high-spatial-resolution reconnaissance to reveal the geological and environmental evolution of this *** to frequent dust storms, not only is the Martian surface covered with dust, but also the spectral calibration panels on the rover are affected by dust coverage. Data from the shortwave infrared(SWIR) spectrometer onboard the rover are also affected by other environmental factors such as instrumental temperature changes and atmospheric carbon dioxide absorption. This study recalibrated the in situ SWIR data to minimize the impact of the above factors. The recalibrated spectral data show that the reflectance of the landing area falls within the normal range of Martian soil, and confirm the presence of several important absorption peaks. The absorption characteristics indicate the presence of polyhydrated sulfates, gypsum, and hydrated silicates in the surface materials along the rover track, with sulfate content of <27–39 wt.%. Our results further confirm past activity of liquid water in the Zhurong rover landing area, providing mineralogical evidence supporting hypotheses related to underground water or an ancient shoreline.

关键词： Mars Water activity In-situ exploration Short-wave infrared spectrum Zhurong rover

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On the Gradient of the Electron Pressure in Anti-Parallel Magnetic Reconnection

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Chinese Physics Letters 2015年第4期32卷 65-68页

作者：王焕宇黄灿陆全明王水 CAS key laboratory of Geospace Environment Department of Geophysics and Planetary ScienceUniversity of Science and Technology of China

We first perform a two-dimensional particle-in-cell simulation of anti-parallel magnetic reconnection to verify that in the electron diffusion region the reconnection electric field is mainly balanced by the gradient of the electron pressure. Then, by following typical electron trajectories in the fixed electromagnetic field of anti- parallel reconnection, we calculate the gradient of the electron pressure. We find that the resulted gradient of the electron pressure is equal to the reconnection electric field. This indicates that in the electron diffusion region the reconnection electric field is balanced by the gradient of the electron pressure, which results from the electron nongyrotropic motions. Our result gives a microphysical explanation of the balance between the reconnection electric field and the gradient of the electron pressure.

关键词： On the Gradient of the Electron Pressure in Anti-Parallel Magnetic Reconnection

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Investigation of the SA evolution by using the CHAOS-4 model over 1997–2013

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Science China Earth Sciences 2016年第5期59卷 1041-1050页

作者： OU JiaMing DU AiMin XU WenYao key laboratory of Earth and Planetary Physics Chinese Academy of Sciences Institute of Geology and geophysics Chinese Academy of Sciences

The temporal and spatial evolution characteristics of the geomagnetic secular acceleration(SA) are investigated, based on CHAOS-4 core field model during the period of 1997–2013. The SA evolution on a short time scale is associated with the phenomenon of the geomagnetic jerk. More details of the global extent and the occurrence time of the successive jerks(the 1999, 2003, 2007, and 2011 jerks) are obtained. The location, size and reversed polarity pattern for the 1999 jerk are similar to those for the 2003 jerk in the Asian-Indian sector. While the 2007 and 2011 jerks mainly take place in the Atlantic sector. The direction and speed of the shift for the four jerks are different, identified by the occurrence time of the jerks. The zonal motions of the SA patches exhibit an oscillation pattern in the Asian-Indian sector, whereas a purely westward drifting pattern is along the equator in the Atlantic sector. It is believed that the shift of the jerks is related to the motion of SA-B_r patches observed at the core-mantle boundary(CMB).

关键词： Geomagnetic secular acceleration Geomagnetic jerk Core-mantle boundary Zonal oscillation

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The influence of Tethyan evolution on changes of the Earth's past environment

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Science China Earth Sciences 2023年第12期66卷 2653-2665页

作者： Bo WAN Fuyuan WU Rixiang ZHU State key laboratory of Lithospheric Evolution Institute of Geology and GeophysicsChinese Academy of SciencesBeijing 100029China

Understanding changes in Earth's past can provide valuable insights into prediction of its *** example is the interactions between the internal and external spheres of *** cyclical northward breakup-drift of Gondwana,driven by the opening and closure of Proto-,Paleo-,and Neo-Tethyan oceans,facilitated the transfer of landmasses from the southern to the northern hemisphere,traversing the tropic *** have observed a compelling correlation between episodic increases in landmass area within the tropic regions(those lying at less than 20°latitude)and a subsequent temperature decrease during the three major glacial periods in the last 500 million *** phenomenon can be attributed to low latitude regions receiving more solar energy influx on Earth's surface than high latitude *** addition,an increase of landmass in tropic regions(low latitude)attenuates the net energy absorption by the Earth's surface,consequently impeding the conduction and convection of absorbed energy toward the *** result is a decrease in global surface *** tropic regions,benefiting from abundant sunlight,create an ideal environment for the proliferation of marine plankton *** species are important in the generation of organic-rich *** biological debris is therefore deposited on continental margins when a continent drifts across the tropic *** creates favorable conditions for future hydrocarbon and reservoir *** subduction of organic-rich sediments during the closure of the Tethyan oceans results in the generation of mafic arc magmas with low oxygen *** chemical environment helps the mineralization of reduced-type ore deposits such as tungsten,tin,and ***-driven plate tectonics in the Tethys realm changes the distribution of oceans and landmass,subsequently affecting the balance and distribution of solar energy across Earth's *** changes trigger consequential environmental shif

关键词： Tethyan geodynamics Earth system Change of sea-land distribution Reduced ore deposit Hydrocarbon

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A new technique for deriving the quiet day curve from imaging riometer data at Zhongshan Station, Antarctic

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Science China(Technological Sciences) 2014年第10期57卷 1967-1976页

作者： HE Fang HU HongQiao HU ZeJun LIU RuiYuan SOA key laboratory for Polar Science Polar Research Institute of China key laboratory of Ionospheric Environment Institute of Geology and Geophysics Chinese Academy of Sciences

A new technique for estimating quiet day curve(QDC)was *** validate the new approach,QDCs were derived from data acquired by the imaging riometer installed at the Chinese Zhongshan Station in *** evaluation was performed by comparing the difference between QDC derived by the new technique and those derived by Tanaka’s *** results were discussed in terms of the diurnal variation and ***,cosmic noise absorption(CNA)images were built using both techniques in order to evaluate the implications of the changes when obtaining them using different methods of the QDC *** influence of the multiplicative factor value on the QDC determination in Tanaka’s technique was evaluated.

关键词： riometer absorption technique

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A fractal approach to low velocity non-Darcy flow in a low permeability porous medium

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Chinese Physics B 2014年第4期23卷 385-389页

作者：蔡建超 Institute of geophysics and Geomatics Key Laboratory of Tectonics and Petroleum Resources of Ministry of Education China University of Geosciences

In this paper, the mechanism for fluid flow at low velocity in a porous medium is analyzed based on plastic flow of oil in a reservoir and the fractal approach. The analytical expressions for flow rate and velocity of non-Newtonian fluid flow in the low permeability porous medium are derived, and the threshold pressure gradient （TPG） is also obtained. It is notable that the TPG （J） and permeability （K） of the porous medium analytically exhibit the scaling behavior J ~ K-D＇r/（l＋Or）, where DT is the fractal dimension for tortuous capillaries. The fractal characteristics of tortuosity for capillaries should be considered in analysis of non-Darcy flow in a low permeability porous medium. The model predictions of TPG show good agreement with those obtained by the available expression and experimental data. The proposed model may be conducible to a better understanding of the mechanism for nonlinear flow in the low permeability porous medium.

关键词： fractal porous media non-Darcy flow threshold pressure gradient scaling law

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Onset location of scintillation-producing spread-F plume over Sanya

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Science China Earth Sciences 2016年第8期59卷 1692-1699页

作者： ZHENG JianChang HUANG ZhaoGuo WU Zhi HAO XiQing JI JiaLun NING BaiQi HU LianHuan ZHAO XiuKuan LI GuoZhu key laboratory of Earth and Planetary Physics Institute of Geology and Geophysics Chinese Academy of Sciences Beijing National Observatory of Space Environment Institute of Geology and Geophysics Chinese Academy of Sciences

Equatorial spread-F (ESF) backscatter plumes are often observed in radar range-time-intensity (RTI) maps at low latitude. Except case studies, few statistical investigations on the onset locations of scintillation-producing ESF plumes at given sites have been conducted. In this study, a statistical analysis is carried out on onset locations of ESF backscatter plumes observed at a low-latitude location Sanya (18.4°N, 109.6°E; dip lat 12.8°N) during equinoctial months of 2013. By employing a tracing method to locate backscatter plumes, we estimate the onset longitudes of periodic plumes obtained from the Sanya VHF radar five-beam steering measurements. The results show that the inter-plume distances (in longitude) are mostly confined within 200–600 km, and the ESF plumes producing ionospheric scintillations over Sanya are almost exclusively generated at the longitudes of 94°–110°E. The results indicate the necessity to monitor ESF plume initial generation in the longitude region of 94°–110°E to better understand the day-to-day variability in the occurrence of ionospheric scintillations over Sanya.

关键词： Equatorial spread-F Backscatter plume Onset location VHF radar Zonal drift

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Magnitude and rupture duration from high frequency teleseismic P wave with projected landweber deconvolution

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Science China Earth Sciences 2013年第1期56卷 13-21页

作者： ZHENG Yong NI SiDao CHEN Yong TAN Ying Don HELMBERGER State key laboratory of Geodesy and Earth's Dynamics Institute of Geodesy and Geophysics Chinese Academy of Sciences Institute of geophysics Chinese Earthquake Administration Seismological laboratory California Institute of Technology

Earthquake magnitude and rupture duration are among the most important parameters characterizing an earthquake for the purpose of early tsunami warning. While they can be routinely determined from broadband P waveforms with iterative inver- sion procedures, the inversion procedures may fail when the rupture either lasts longer than the interval between P and later ar- rivals or requires too much time or human intervention. Little contaminated by later arrivals, high frequency P waves are useful for modeling earthquake source processes, though the envelope waveform is affected by strong scattering in lithosphere. With high frequency envelopes from aftershocks as Empirical Green＇s Function （EGF）, the coda effects can be removed and more accurate relative source time function （RSTF） of the main shock can be obtained. Assuming that RSTFs cannot be negative, we use the projected Landweber deconvolution method （PLD） to obtain high frequency RSTFs because PLD method has the ad- vantage of non-negativity, causality, and compactness （finite duration）. We are able to determine rupture durations of four large earthquakes： the 2004 Sumatra-Andaman earthquake, the 2005 Nias event, the 2006 Java event, and the 2011 Tokuko earthquake. The rupture durations of the Sumatra-Andaman, Nias, and Tohuko events are found to be around 550, 1 i0, and 120 s respectively, consistent with previous studies. The rupture duration of the Java event is about 130 s, supporting that the Java event is a tsunami earthquake. The magnitudes of these earthquakes are found to depend on both the amplitude and the duration of the deconvolved waveforms, and can be approximated by integrating these waveforms.

关键词： high frequency deconvolution rupture duration magnitude

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Growth characteristics and sedimentary mode of Permian reefs,Lengwu,Tonglu,Zhejiang Province,southern China

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Journal of Palaeogeography 2016年第4期5卷 409-422页

作者： Ling Liu Ya-Sheng Wu Hong-Xia Jiang Hong Liu Institute of Geology and geophysics CASKey Laboratory of Petroleum Resource ResearchChinese Academy of Sciences

Organic reefs are favourabte accumulation spaces for hydrocarbons and various mineral resources. A complete Permian organic reef profile about 44 m thick with distribution area no more than 1 km2 is exposed near Lengwu, Tongtu, Zhejiang Province. Examination of outcrops and thin sections revealed that the main reef-building organisms are catcisponges, with inozoans as dominant type. Five types of rocks have been recognized in the reef, and they are catcisponge framestone, catcisponge bafflestone, bindstone, rudstone and bioctastic wackestone. The profile was constructed in three reef-building stages. The thickness of the second stage is largest, followed by the first stage and the third stage is smallest. Each stage started with a frame-stone or bafflestone, ended as the reef grew near the sea-level, and died because of influx of terrigenous sediments. The development of the Lengwu reef is controlled by biological factors and sea-level changes. Based on the study a reef sedimentary model is established.

关键词： Reef Rock types Calcisponges Sedimentary model Permian Lengwu Southern China

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Towards combining multiple geophysical datasets to determine earthquake source parameters in China

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Science China Earth Sciences 2016年第11期59卷 2260-2262页

作者： ZHENG Yong LIU ChengLi State key laboratory of Geodesy and Earth's Dynamics Institute of Geodesy and Geophysics Chinese Academy of Sciences

*** of conventional seismic studies on earthquake source parameters Earthquake source parameters,including magnitude,location,focal mechanism,rupture process are key factors for understanding seismogenic environment,mitigating seismic hazards,estimating earthquake triggering,and tectonic ***,source parameters are determined by seismological *** example,Fang L H et al.（2014）relocated the 2012 Ms6.6 Xinjiang Xinyuan earthquake sequence using local seismograms based on the double difference method,

关键词： geophysical tectonic rupture triggering magnitude estimating moderate epicenter constrain spatially

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