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Multiple thermal events recorded in the Acasta Gneiss Complex:Evidence from in-situ dating of zircon, titanite, and apatite

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Science China Earth Sciences 2024年第3期67卷 673-686页

作者： Qingfeng MEI Jinhui YANG Jinfeng SUN Qiuli LI Shitou WU Xiaoxiao LING Peng PENG Hao WANG State Key laboratory of Lithospheric Evolution Institute of Geology and GeophysicsChinese Academy of SciencesBeijing 100029China College of Earth and Planetary Sciences University of Chinese Academy of SciencesBeijing 100049China Key laboratory of computational geodynamics University of Chinese Academy of SciencesBeijing 100049China

In-situ dating of the zircons, titanites, and apatites in the rock fragments of approximately 1 cm2in size from the Acasta Gneiss Complex was performed using secondary ion mass spectrometry or laser ablation inductively coupled plasma mass spectrometry to provide constraints on the thermal history of the Acasta Gneiss Complex. The zircons in these rock fragments typically exhibit multiple age populations, reflecting the presence of inherited zircons or the post-crystallization process of zircon overgrowth. Combined with previous studies, our zircon dating results reveal multiple magmatic events that occurred in the Acasta Gneiss Complex, specifically at >3.96, ~3.72, and ~3.57 Ga, respectively. A titanite Pb-Pb isochron age of2911±22 Ma(95% confidence level, MSWD=1.5) for sample AY199 is identified, consistent with the timing of the latest Archean magmatism in the Acasta Gneiss Complex. The titanite U-Pb ages for samples AC478 and AY066 are 1932±270 Ma(95% confidence level, MSWD=2.3) and 1813±45 Ma(95% confidence level, MSWD=2.3), respectively. The apatites in sample P090803-C exhibit a Pb-Pb isochron age of 1833±26 Ma(95% confidence level, MSWD=1.4). The apatite U-Pb ages for samples AC478, AY199, and AY066 are 1850±20 Ma(95% confidence level, MSWD=1.3), 1827±100 Ma(95% confidence level, MSWD=6.3), and 1807±58 Ma(95% confidence level, MSWD=3.9), respectively. Titanites in samples AC478 and AY066, as well as the apatites in all four investigated samples, show a uniform age(Pb-Pb or U-Pb age) of ~1.9–1.8 Ga,indicating U-Pb system reset in these minerals due to the Wopmay orogeny and documenting that the peak temperature condition associated with the Wopmay orogeny exceeded the apatite U-Pb closure temperature and approached or exceeded that of titanite.

关键词： Zircon Titanite Apatite Acasta Gneiss Complex Wopmay Orogen

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Present-day Upper-crustal Strain Rate Field in Southeastern Tibet and its Geodynamic Implications:Constraints from GPS Measurements with ABIC Method

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Acta Geologica Sinica(English Edition) 2024年第1期98卷 265-275页

作者： YANG Shaohua PAN Jiawei LI Haibing SHI Yaolin Key laboratory of Continental Dynamics of Ministry of Natural Resources Institute of GeologyChinese Academy of Geological SciencesBeijing 100037China Jiangsu Donghai Continental Deep Hole Crustal Activity National Observation and Research Station DonghaiJiangsu 222300China Key laboratory of computational geodynamics College of Earth and Planetary SciencesUniversity of Chinese Academy of SciencesBeijing 100049China

The Earth’s surface kinematics and deformation are fundamental to understanding crustal *** effective research approach is to estimate regional motion field and deformation fields based on modern geodetic *** the discrete observed velocity field is obtained,the velocity related fields,such as dilatation rate and maximum shear strain rate,can be estimated by applying varied mathematical *** study applied Akaike's Bayesian Information Criterion(ABIC)method to calculate strain rate fields constrained by GPS observations in the southeast Tibetan *** with results derived from other three methods revealed that our ABIC-derived strain rate fields were more *** maximum shear strain rate highlighted the Xianshuihe–Xiaojiang fault system as the main boundary for the outward migration of material in southeastern Tibet,indicating rotation of eastern Tibet material around the eastern Himalaya rather than whole extrusion along a fixed ***,distinct dilatation rate patterns in the northeast and southwest regions of the fault system were *** northeast region,represented by the Longmenshan area,exhibited negative dilatational anomalies;while the southwest region,represented by the Jinsha River area north of 29°N,displayed positive dilatational *** indicates compression in the former and extension in the *** with deep geophysical observations,we believe that the upper and lower crusts of the Jinsha River area north of 29°N are in an entire expanding state,probably caused by the escape-drag effect of *** presence of a large,low-viscosity region south of 29°N may not enable the entire escape of the crust,but instead result in a differential escape of the lower crust faster than the upper crust.

关键词： strain rate differential escape ABIC GPS southeastern Tibet

Seismicity changes and numerical simulation of coseismic deformation following the 2022 M_(s)6.8 Luding earthquake in Sichuan,China

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Science China Earth Sciences 2024年第8期67卷 2507-2521页

作者： Qiu MENG Zitao WANG Huai ZHANG Key laboratory of computational geodynamics of Chinese Academy of Sciences College of Earth and Planetary SciencesUniversity of Chinese Academy of SciencesBeijing 100049China Institute of Earthquake Forecasting China Earthquake AdministrationBeijing 100036China Southern Marine Science and Engineering Guangdong laboratory(Zhuhai) Zhuhai 519080China Beijing Yanshan Earth Critical Zone National Research Station Beijing 101408China

The Xianshuihe fault is a major tectonic boundary between the Sichuan-Yunnan rhombic and Bayanhar blocks in Southwest *** an average left-lateral strike-slip movement of 10–15 mm/yr,it is a fast-moving strike-slip continental *** September 5,2022,the Ms6.8 Luding earthquake occurred along the Moxi segment of the Xianshuihe fault,reaching a maximum intensity of IX and resulting in a significant number of casualties and severe property *** earthquake broke the long-standing seismic quiescence of the Xianshuihe fault,which lasted for more than 40 years,and was followed by a significant number of *** outstanding question is how the behavior of the Xianshuihe fault and major earthquakes changed following this *** this study,we examined the changes in regional seismicity following the Luding earthquake and identified the potential for future strong earthquakes along the Xianshuihe *** used a finite element numerical method to simulate the environment of the seismogenic fault and its adjacent *** addition,we used the coseismic slip model of the Luding earthquake with the split-node method to calculate how the stress and strain fields in the surrounding area were affected by the2022 *** stress changes were resolved in the main faults,and the seismicity of adjacent faults was analyzed in conjunction with the observed seismic *** results indicate that regional tectonic movement primarily occurred to the southeast along the Moxi *** stress field is approximately north-south in tension and east-west in *** in the stress field in the epicentral region of the Luding earthquake exceeded 1 *** maximum displacement of the coseismic deformation field was concentrated between Moxi town and Tuanjie village,and the Coulomb stress of the fault zone in this region experienced the largest ***,the b-value of the Gutenberg-Richter magnitude-frequency relationship at the epicenter a

关键词： Luding earthquake Seismicity Coulomb failure stress change Finite element numerical simulation

Seismicity changes and numerical simulation of coseismic deformation following the 2022 M6.8 Luding earthquake in Sichuan, China

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Science China Earth Sciences 2024年

作者： Qiu MENG Zitao WANG Huai ZHANG Key laboratory of computational geodynamics of Chinese Academy of Sciences College of Earth and Planetary SciencesUniversity of Chinese Academy of Sciences Institute of Earthquake Forecasting China Earthquake Administration Southern Marine Science and Engineering Guangdong laboratory (Zhuhai) Beijing Yanshan Earth Critical Zone National Research Station

The Xianshuihe fault is a major tectonic boundary between the Sichuan-Yunnan rhombic and Bayanhar blocks in Southwest *** an average left-lateral strike-slip movement of 10–15 mm/yr, it is a fast-moving strike-slip continental fault. On September 5, 2022, the Ms6.8 Luding earthquake occurred along the Moxi segment of the Xianshuihe fault, reaching a maximum intensity of IX and resulting in a significant number of casualties and severe property damage. This earthquake broke the long-standing seismic quiescence of the Xianshuihe fault, which lasted for more than 40 years, and was followed by a significant number of aftershocks. An outstanding question is how the behavior of the Xianshuihe fault and major earthquakes changed following this mainshock. In this study, we examined the changes in regional seismicity following the Luding earthquake and identified the potential for future strong earthquakes along the Xianshuihe fault. We used a finite element numerical method to simulate the environment of the seismogenic fault and its adjacent areas. In addition, we used the coseismic slip model of the Luding earthquake with the split-node method to calculate how the stress and strain fields in the surrounding area were affected by the2022 mainshock. Coulomb stress changes were resolved in the main faults, and the seismicity of adjacent faults was analyzed in conjunction with the observed seismic data. The results indicate that regional tectonic movement primarily occurred to the southeast along the Moxi segment. The stress field is approximately north-south in tension and east-west in *** in the stress field in the epicentral region of the Luding earthquake exceeded 1 MPa. The maximum displacement of the coseismic deformation field was concentrated between Moxi town and Tuanjie village, and the Coulomb stress of the fault zone in this region experienced the largest decrease. However, the b-value of the Gutenberg-Richter magnitude-frequency relations

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Seismic and geological evidence of hidden faults in the Yinpan Reservoir area based on a dense seismic array

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Science China Earth Sciences 2024年第7期67卷 2401-2407页

作者： Guangyao YIN Huai ZHANG Liwen GONG Q ipeng BAI Yicun GUO Bing ZHANG Yaolin SHI Key laboratoryof Earth System Numerical Modeling and Application(Chinese Academyof Sciences) College of Earth and Planetary SciencesUniversity of Chinese Academy of SciencesBeijing 100049China Key laboratory of computational geodynamics Chinese Academy of SciencesBeijing 100049China Southern Marine Science and Engineering Guangdong laboratory(Zhuhai) Zhuhai 519080China Beijing Yanshan Critical Zone National Field Scientific Observation and Research Station Beijing 101408China Chongqing Earthquake Agency Chongqing 401147 China Institute of Earthquake Forecasting China Earthquake AdministrationBeijing 100036China Hangzhou Applied Acoustics Research Institute Hangzhou 311100China State Key laboratory of Geodesy and Earths Dynamics Innovation Academy for Precision Measurement Science and TechnologyCASWuhan 430077China

*** November 23,2017,an M_(S)5.0 earthquake occurred in Wulong,Chongqing,China,resulting in tens of casualties and considerable economic ***,the epicenter of this earthquake was located in the transition zone from the... 详细信息

关键词： earthquake southeast seismic

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Finite element simulation of deformation and stress changes of Kalpin-Kemin fault system in the Southwest Tianshan Orogenic Belt

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Science China Earth Sciences 2022年第5期65卷 863-873页

作者： Zitao WANG Huai ZHANG Qiu MENG Yaolin SHI Key laboratory of computational geodynamics University of Chinese Academy of SciencesBeijing 100049China

Under the shadow of the far-field effect of the India-Eurasia collision,the Tianshan orogenic belt underwent tectonic re-activation in the Cenozoic,accompanied by strong tectonic deformation and frequent large *** by two rigid cratonic blocks located in its north and south,a series of marginal foreland fold-and-thrust belts are developed within the Tianshan orogenic belt and continue to develop to the bilateral pull-apart ***,the faults in the orogenic belt are *** deformation caused by thrust-related structure accounts for larger than 50%of the total convergence of the Tianshan Mountains,which results in the most active structure with large earthquakes in the Tianshan ***,it is of great significance to study the dynamic process of the newly generated and reactivated thrust-nappe structures in Tianshan orogen via numerical *** paper selects a classical cross-section profile in the western segment of the Southwest Tianshan Mountains,which contains the Kalpin-Maidan-Nalati-Kemin fault system from the south to the *** attempt to establish a two-dimensional plane strain,viscoelastic finite element model,by treating the regional faults as a whole fault system and considering the topography,fault geometry,and GPS *** displacement and stress fields of the model are retrieved,the short-term cumulative deformation field of the overall fault system is analyzed,and the rate of Coulomb failure stress change of each fault is also *** results show that the deformation is concentrated in the middle and southern parts of the Southwest Tianshan *** contrast,the deformation of the Kemin fault in the north is relatively *** to the Coulomb failure stress changes of these four faults and the historical earthquake catalog,the potential seismicity of each fault is qualitatively *** preliminary results suggest that the possibility of large earthquake occurrence is higher in the

关键词： Tianshan orogenic belt Viscoelastic finite element Coulomb failure stress change Seismicity

Key geodynamic processes and driving forces of Tethyan evolution

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Science China Earth Sciences 2023年第12期66卷 2666-2685页

作者： Zhong-Hai LI Fengyuan CUI Shuting YANG Xinyi ZHONG Key laboratory of computational geodynamics College of Earth and Planetary SciencesUniversity of Chinese Academy of SciencesBeijing 100049China

Tethys tectonic system has experienced a long-term evolution history,including multiple Wilson cycles;thus,it is an ideal target for analyzing plate tectonics and *** evolution is typically characterized by a series of continental blocks that separated from the Gondwana in the Southern Hemisphere,drifted northward,and collided and accreted with Laurasia in the Northern *** this process,the successive opening and closing of multistage Tethys oceans(e.g.,Proto-Tethys,Paleo-Tethys,and Neo-Tethys)are considered core parts of the Tethyan ***,focusing on the life cycle of an oceanic plate,four key geodynamic processes during the Tethyan evolution,namely,continental margin breakup,subduction initiation(SI),Mid-Ocean Ridge(MOR)subduction,and continental collision,were highlighted and dynamically analyzed to gather the following insights.(1)Breakup of the narrow continental margin terranes from the northern Gondwana is probably controlled by plate subduction,particularly the subduction-induced far-field *** breakup of the Indian continent and the subsequent spreading of the Indian Ocean can be attributed to the interactions between multiple mantle plumes and slab drag-induced far-field stretching.(2)Continental margin terrane collision-induced subduction transference/jump is a key factor in progressive Tethyan evolution,which is driven by the combined forces of collision-induced reverse push,far-field ridge push,and mantle flow ***,lithospheric weakening plays an important role in the occurrence of SI.(3)MOR subduction is generally accompanied by slab *** case of the considerably reduced or temporary absence of slab pull,mantle flow traction may contribute to the progression of plate *** subduction can dynamically influence the overriding and downgoing plates by producing important and diagnostic geological records.(4)The large gravitational potential energy of the Tibetan Plateau indicat

关键词： Continental margin breakup Subduction initiation Mid-Ocean Ridge subduction Continental collision Tethys geodynamics

Suitable region of dynamic optimal interpolation for efficiently altimetry sea surface height mapping

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Geodesy and geodynamics 2024年第2期15卷 142-149页

作者： Jiasheng Shi Taoyong Jin School of Geodesy and Geomatics Hubei Luojia LaboratoryWuhan UniversityWuhan 430079China MOE Key laboratory of Geospace Environment and Geodesy Wuhan UniversityWuhan 430079China

The dynamic optimal interpolation(DOI)method is a technique based on quasi-geostrophic dynamics for merging multi-satellite altimeter along-track observations to generate gridded absolute dynamic topography(ADT).Compared with the linear optimal interpolation(LOI)method,the DOI method can improve the accuracy of gridded ADT locally but with low computational ***,considering both computational efficiency and accuracy,the DOI method is more suitable to be used only for regional *** this study,we propose to evaluate the suitable region for applying the DOI method based on the correlation between the absolute value of the Jacobian operator of the geostrophic stream function and the improvement achieved by the DOI *** verifying the LOI and DOI methods,the suitable region was investigated in three typical areas:the Gulf Stream(25°N-50°N,55°W-80°W),the Japanese Kuroshio(25°N-45°N,135°E-155°E),and the South China Sea(5°N-25°N,100°E-125°E).We propose to use the DOI method only in regions outside the equatorial region and where the absolute value of the Jacobian operator of the geostrophic stream function is higher than1×10^(-11).

关键词： Dynamic optimal interpolation Linearoptimal interpolation Satellite altimetry Sea surface height Suitable region

Consistency analysis of GRACE and GRACE-FO data in the study of global mean sea level change

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Geodesy and geodynamics 2022年第4期13卷 321-326页

作者： Le Chang Wenke Sun College of Geodesy and Geomatics Shandong University of Science and TechnologyQingdao266590China Key laboratory of computational geodynamics University of Chinese Academy of SciencesBeijing100049China

Global mean sea level(GMSL) change is one of the important indicators of global climate change and is a crucial scientific issue of continuing interest. As satellite altimeter data, the Gravity Recovery and Climate Experiment(GRACE) and Argo continue to be updated, especially with the release of GRACE Follow-On(GRACE-FO) data, making it necessary to combine these latest data to estimate sea level change. Determinations on whether the GRACE and GRACE-FO observation systems provide unbiased global observation data have not been effectively evaluated. Therefore, this research mainly investigated the consistency of GRACE and GRACE-FO observation data in studying GMSL change. By comparing the sum of the GMSL calculated by the two gravity satellites and Argo data with the GMSL calculated by satellite altimeters, the discrepancy between GRACE-FO + Argo and satellite altimeter data is about 7.9 ± 2.3 mm, which is likely derived from the inconsistency between GRACE and GRACE-FO data.

关键词： GMSL GRACE GRACE-FO Altimetry Argo