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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

The first 10 m resolution thermokarst lake and pond dataset for the Lena Basin in the 2020 thawing season

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Big Earth Data 2024年第2期8卷 302-332页

作者： Yining Yu Fengming Hui Yu Zhou Chong Liu Xiao Cheng School of Geospatial Engineering and Science Sun Yat-sen Universityand Southern Marine Science and Engineering Guangdong Laboratory(Zhuhai)ZhuhaiChina Key laboratory of Comprehensive Observation of Polar Environment (Sun Yat-sen University)Ministry of EducationZhuhaiChina Guangdong Provincial Key laboratory of geodynamics and Geohazards School of Earth Sciences and EngineeringSun Yat-sen UniversityZhuhaiChina

Climate warming rates in the Arctic are far greater than the global average,exerting stronger impacts on permafrost degradation and thermokarst landform *** lakes and ponds(TLPs),which are widely distributed in the Lena Basin in the Russian Arctic,play a vital role in altering local ***,the detailed distribution of TLPs in the Lena Basin still remains poorly *** this study,we built the first 10 m resolution TLP dataset for the Lena Basin in the 2020 thawing season by utilizing 4902 Sentinel-2 images.A robust mapping workflow was developed and implemented in the Google Earth Engine(GEE)*** accu-racy assessment demonstrates a satisfactory accuracy(93.63%),and our results exhibit a better consistency with real TLPs than global water body products.A total of 380,477 TLPs(~0.53%of the total surface area of the Lena Basin)were identified,showing an uneven distribution in the five *** TLPs were found to be mainly located within plain areas,with an active layer thickness in the range of 80-100 *** higher ground ice content and mean annual ground temperature were favorable for TLP *** dataset will be valuable for investigating the complex interac-tion between TLPs and *** will also serve as a baseline product for better incorporating thermokarst processes into perma-frostclimate models.

关键词： Thermokarst lakes and ponds Lena Basin permafrost GEE Sentinel-2

The role of sub-continental lithosphere mantle in deep F and Cl cycling: Insight from the Dabeigou basalts, North China Craton

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Science China Earth Sciences 2024年

作者： Yadong WU Jinhui YANG Jinfeng SUN Hao WANG Baoquan ZHOU State Key laboratory of Lithospheric Evolution Institute of Geology and Geophysics Chinese Academy of Sciences College of Earth and Planetary Sciences University of Chinese Academy of Sciences Key laboratory of Computational geodynamics University of Chinese Academy of Sciences

The sub-continental lithosphere mantle （SCLM） represents a mechanical barrier that separate the convecting mantle from the exosphere,and possesses the ability to sequester and release volatiles,making it an integral part in deep volatile *** we explore the SCLM in modulating F and Cl cycling through a case study from the Early Cretaceous Dabeigou basalts in the North China Craton （NCC）.These lavas are associated with decratonization of the NCC,a process involving significant removal and replacement of the ancient *** Dabeigou basalts,characterized by arc magma-like trace element signatures,evolved initial87Sr/86Sr （0.70574–0.70578）,εNd（t）(-11.2–-11.1),and εHf（t）(-13.7–-13.4) values,along with high Fe/Mn ratios,Ni contents,and δ18O values （5.8‰–6.8‰） of olivine phenocrysts,are compatible with their origination from a veined,pyroxene-rich source formed through the infiltration and interaction of hydrous silicate melts from the subducting Pacific slabs with ambient ***-hosted melt inclusions of the Dabeigou basalts have compositions similar to the whole rocks,indicating that they record pre-eruptive melt compositions forming the whole *** melt inclusions exhibit high F（1371–2316 ppm） and moderate Cl （688–900 ppm） contents,with high F/Cl ratios of 2.1±0.3 （1σ）.The F and Cl signatures of the Dabeigou basalts are different from those of typical arc magmas,which are commonly characterized by high Cl contents （median of～1200 ppm） and low F/Cl ratios （<1）.The observed differences can be attributed to chromatographic reaction that fractionates elements of different compatibility in the metasomatic agents,with amphibole as the main mineral phase for fractionating and preserving F and *** is,amphibole crystallization prefers to retain F rather than Cl,making the metasomes in vein enriched in F and exhibiting elevated F/Cl ratios compared to original metasomatic *** is further suggested that the scenario inferred from the Dabeigou basalts m

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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

Low-latitude hydroclimate changes related to paleomagnetic variations during the Holocene in coastal southern China

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Frontiers of Earth Science 2024年第2期18卷 324-335页

作者： Tingwei ZHANG Xiaoqiang YANG Jian YIN Qiong CHEN Jianfang HU Lu WANG Mengshan JU Qiangqiang WANG School of Earth Science and Engineering/Guangdong Provincial Key Laboratory of Geodynamics and Geohazards/Southern Marine Science and Engineering Guangdong Laboratory(Zhuhai)Sun Yat-sen UniversityGuangzhou 510275China Institute of Cultural Heritage Shandong UniversityQingdao 266237China State Key laboratory of Organic Geochemistry Guangzhou Institute of GeochemistryChinese Academy of SciencesGuangzhou 510640China College of Urban and Environmental Sciences Peking UniversityBeijing 100871China Institute of Oceanology Chinese Academy of SciencesQingdao 266071China

The variations in precipitation have displayed a complex pattern in different regions since the *** formation processes may have a significant impact on precipitation,especially during the tropical marine processes and summer monsoon which convey abundant water vapor to coastal southern China and inland ***,we use two 7500 year sedimentary records from the Pearl River Delta and the closed Maar Lake,respectively,in coastal southern China to reconstruct the mid-to-late-Holocene humidity variability and explore its possible relationship with cloud cover modulated by the Earth’s magnetic fields(EMF).Our proxy records document an apparent increase in wetness in coastal southern China between 3.0 and 1.8 kyr *** apparent increase in humidity appears to be consistent with the lower virtual axial dipole moments and,in turn,with a lower *** correlation suggests that the EMF might have been superimposed on the weakened monsoon to regulate the mid-to-late-Holocene hydroclimate in coastal southern China through the medium of galactic cosmic rays,aerosols,and cloud ***,further investigations are needed to verify this interaction.

关键词： hydroclimate variations Earth’s magnetic field coastal southern China the Holocene epoch

Provenance and paleogeographic evolution of the Upper Paleozoic–Lower Mesozoic strata in northern Laos

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Journal of Earth Science 2024年

作者： Jingjie Jin Xin Qian Vongpaseuth Senebouttalath Yuzhi Zhang Yuejun Wang Guangdong Provincial Key Lab of geodynamics and Geohazards， School of Earth Sciences and Engineering， Sun Yat-sen University， and Southern Marine Science and Engineering Guangdong laboratory (Zhuhai) Ministry of Energy and Mines， Department of Geology and Minerals

The Late Paleozoic–Early Mesozoic sedimentary system of the Luang Prabang Paleotethyan back-arc basin in northern Laos is important for investigating sedimentary provenance， paleogeographic patterns， and the tectonic evolution of the Eastern Paleotethyan Ocean. This study presents systematic stratigraphy， petrology， geochemistry， and detrital zircon U–Pb–Hf isotopic analyses for the Late Carboniferous–Jurassic sedimentary strata on both sides of the Luang Prabang basin. Based on distinct stratigraphic ages and provenance characteristics， the clastic rock samples can be divided into four groups. The Group 1 Late Carboniferous–Early Permian samples from the western part of the basin yield detrital zircon age-peaks of ～348 and ～1425 Ma， with corresponding εHf(t) values ranging from -2.0 to +15.5 and +1.5 to +14， respectively. The age spectrum of Group 2 Late Carboniferous–Early Permian samples from the eastern part of the basin shows major age-peaks of ～287 and ～1860 Ma， with εHf(t) values of -5.9–-0.9 and -3.6–+4.2， respectively. Group 3 Late Permian–Triassic samples exhibit age-peaks of ～242 and ～1853 Ma， along with εHf(t) values of -0.7–+14.4 and -5.4–-1.8， respectively. Group 4 Middle–Late Jurassic samples yield age-peaks of ～237，～431，～813，～1833， and ～2460 Ma， lacking Late Devonian (413–345 Ma) detrital zircons. All these data collectively suggest that the Group 1 sample primarily originated from the Sukhothai Arc in western Indochina， Group 2 was from the Kontum and Truong Son in eastern Indochina， and Group 3 has a combined provenance of the Sukhothai， Kontum， and Truong Son. Regional comparisons suggest that the Jurassic provenance was mainly derived from South China， which was imported through the northern river system. Our data， combined with the regional angular unconformities between Jurassic continental strata and pre-Jurassic marine strata， suggest that the Luang Prabang basin transformed into a superimposed collisional retroforeland basin during the Ju

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Early Cretaceous Metasomatized Lithospheric Mantle beneath the Central Jiangnan Orogen in South China:Geochemical and Sr-Nd Isotope Evidence from the Tuanshanbei Dolerite

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Acta Geologica Sinica(English Edition) 2024年第3期98卷 602-616页

作者： WANG Cheng WEI Hantao LIU Qingquan YANG Zhao Guangdong Provincial Key laboratory of geodynamics and Geohazards School of Earth Sciences and EngineeringSun Yat-sen UniversityGuangzhou 510275China Key laboratory of Metallogenic Prediction of Nonferrous Metals and Geological Environment Monitoring Ministry of EducationSchool of Geosciences and Info-PhysicsCentral South UniversityChangsha 410083China Development and Research Centre China Geological SurveyBeijing 100037China School of Environmental Studies China University of GeosciencesWuhan 430074China

It is well established that Cretaceous magmatism in the South China Block(SCB)is related to the Paleo-Pacific ***,the starting time and the associated deep crust-mantle processes are still *** dike swarms carry important information on the deep earth(including mantle)geodynamics and geochemical *** the Jiangnan Orogen(South China).there is no information on whether the Mesozoic magmatic activities in this region are also directly related to the Pacific subduction or *** this study,we present detailed zircon U-Pb geochronological,wholerock element and Sr-Nd isotope data for Early Cretaceous Tuanshanbei dolerite dikes,and provide new constraints on the condition of the lithospheric mantle and mantle dynamics of the SCB during that ***-ICP-MS zircon U-Pb dating suggests that this dolerite erupted in the Early Cretaceous(~145 Ma).All samples have alkaline geochemical affinities with K_(2)O+Na_(2)O=3.11-4.04 wt%,K_(2)O/Na_(2)O=0.50-0.72,and Mg^(#)=*** are enriched in LILE but depleted in HFSE with higher initial^(87)Sr/^(86)Sr ratio(0.706896-0.714743)and lower ε_(Nd)(t)(-2.61 to-1.67).They have high Nb/U,Nb/La,La/Sm and Rb/Sr,and low La/Nb,La/Ta,Ce/Pb,Ba/Rb,Tb/Yb and Gd/Yb *** geochemical signatures suggest that the fractional crystallization is obvious but crustal contamination play a negligible role during magmatic *** dolerite were most likely derived from low-degree(2%-5%)partial melting of a phlogopite-bearing mantle material consisted of~85% spinel peridotite and~15% garnet peridotite previously metasomatized by asthenospherederived fluids/melts with minor subduction-derived fluids/***-rollback generally lead to the upwelling of the hot *** upwelling of asthenosphere consuming the lithospheric mantle by thermo-mechanical-chemical *** lithospheric mantle may have partially melted due to the heating by the upwelling asthenosphere and lithospheric extension.I

关键词： Early Cretaceous mafic dike metasomatized lithospheric mantle Tuanshanbei dolerite Jiangnan Orogen South China

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