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Acta Geochimica 2018年第2期37卷 295-309页

作者： Miao He Quanlin Hou Qing Liu Jiheng Zhang Jinfeng Sun Shichong Wu Haofeng Zhu Key Laboratory of computational Geodynamics Chinese Academy of Sciences College of earth Science University of Chinese Academy of Sciences 416 Geological Team Bureau of Geology and Mineral Exploration and Development of Hunan Province

Xitian tin-polymetallic deposit, located in the eastern Hunan Province, SE China, hosts quartz vein and skarn in the contact zone between carbonate and two stages granites. Critical geodynamic questions for South China are whether different types of mineralization form in the same time and how the magmatism–tectonic system controls the ore-forming process. Based on the distribution of the orebodies, six cassiterite samples from different types of mineralization are collected for dating. In-situ LA-MCICP-MS U–Pb isotopic data yielded concordia low intercept ages between 154 and 157 Ma, indicating that different types of mineralization belong to the same magmatism–mineralization system. Coupled with the study of the kinematic indicators, it suggests that the structural control of the wall rocks constrain the types of mineralization. These results provide further evidence of a close temporal link between the structure and the tin-polymetallic mineralization in Xitian deposit. Considering the structure in the district, granite dome plays an important role in the ore-forming process. The age and structural signatures in Xitian deposit are the response to the subduction of Pacific Plate.

关键词： LA-MC-ICP-MS U-Pb dating Structure control Tin-polymetallic deposit SE China

Regional Stress Fields under Tibet from 3D Global Flow Simulation

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Journal of earth Science 2011年第2期22卷 155-159页

作者：张斯奇 David A Yuen 张怀石耀霖 Laboratory of computational Geodynamics Graduate University of Chinese Academy of Sciences earth System sciences computational Center The University of QueenslandSt LuciaQLD 4072Australia Department of Geology and Geophysics and Minnesota Supercomputing Institute University of MinnesotaMinneapolisMN 55415USA

Tibetan area is the most active continental collision zone on earth. Several major earthquakes occurred around the boundaries of Tibetan plateau and caused massive damages and casualties. The dynamics of this area is not well understood due to the complex structure of Tibet and its surrounding area. In this study, a 3D global flow simulation with only viscous rheology is applied to studying the stress distribution in this area, and the interaction between Tibet and its surrounding areas is investigated. Finally, the possibility of combining regional modeling with global models is also discussed.

关键词： Tibet global flow stress simulation.

Influence of Tropical Cyclone Landfalls on Spatiotemporal Variations in Typhoon Season Rainfall over South China

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Advances in Atmospheric sciences 2010年第2期27卷 443-454页

作者： Min-Hee LEE Chang-Hoi HO Joo-Hong KIM computational Science and Technology Seoul National University School of earth and Environmental sciences Seoul National University Met Office Hadley Centre

This study examined the impact of tropical cyclone (TC) landfalls on the spatiotemporal variations in the rainfall over South China for the period 1957–2005. The target region was selected to show the noteworthy contribution of TC landfalls to the total rainfall during the typhoon season (July–October). Two prevailing spatial variations in the rainfall were obtained from an EOF analysis. The first EOF mode displays singlesign variability over South China with an explained variance of 23.4%. The associated time series of this mode fluctuates on a decadal timescale and was found to be correlated with TC genesis in the South China Sea. The second EOF mode shows a seesaw pattern between Hainan Island/Guangdong Province and the remaining regions with an explained variance of 11.4%. This seesaw pattern results from an anti-correlation in seasonal TC landfalls between the two regions, which was found in previous studies. This is related to the strengthening (weakening) of the upper tropospheric jets and the corresponding development of a massive anticyclonic (cyclonic) circulation over East Asia. The EOF analysis was also conducted using just the data for rainfall caused by landfalling TCs. This revealed that the first EOF mode using just the TC-induced rainfall is nearly identical to the second mode from the total rainfall. The obvious seesaw pattern of the first mode when employing just the TC-induced rainfall in the EOF analysis implies that this pattern has larger temporal variability than the single-signed pattern (i.e., the first EOF mode using the total rainfall) in terms of TC landfalls. This study suggests that TC landfalls over South China and the accompanying rainfall significantly modulate the spatial variation of the typhoon season rainfall there.

关键词： rainfall tropical cyclone South China typhoon season

A new alternative approach for investigating acidization dissolution front propagation in fluid-saturated carbonate rocks

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Science China(Technological sciences) 2017年第8期60卷 1197-1210页

作者： ZHAO ChongBin HOBBS Bruce ORD Alison computational Geosciences Research Centre Central South University School of earth and Environment The University of Western Australia

The natural phenomenon associated with the chemical dissolution of dissolvable minerals of rocks can be employed to develop innovative technology in mining and oil extracting engineering. This paper presents a new alternative approach for theoretically dealing with chemical dissolution front （CDF） propagation in fluid-saturated carbonate rocks. Note that the CDF is represented by the porosity front in this study. In this new approach, the porosity, pore-fluid velocity and acid concentration are directly used as independent variables. To illustrate how to use the present new approach, an aeidization dissolution system （ADS） consisting of carbonate rocks, which belongs to one of the many general chemical dissolution systems （CDSs）, is taken as an application example. When the acid dissolution capacity （ADC） number （that is defined as the ratio of the volume of the carbonate rock dissolved by an acid to that of the acid） approaches zero, the present new approach can be used to obtain analytical solutions for the stable ADS. However, if the ADC number is a nonzero finite number, then numerical solutions can be only obtained for the ADS, especially when the ADS is in an unstable state. The related theoretical results have demonstrated that：（1） When the ADS is in a stable state and in the case of the ADC number approaching zero, the present new approach is mathematically equivalent to the previous approach, in which the porosity, pore-fluid pressure and acid concentration are used as independent variables. However, when the ADS is in an unstable state, the use of the present new approach leads to a free parameter that needs to be determined by some other ways. （2） The existence of a non-step-type dissolution front within a transient region should at least satisfy that none of the ADC number, injected acid velocity and reciprocal of the dissolution reaction rate is equal to zero in the stable ADS.

关键词： acidization dissolution front propagation critical length alternative approach critical time carbonate rocks

Numerical simulation of landslide-generated tsunamis in lakes:A case study of the Xiluodu Reservoir

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Science China earth sciences 2023年第2期66卷 393-407页

作者： Ting HUANG Huai ZHANG Yaolin SHI Key Laboratory of computational Geodynamics College of Earth and Planetary SciencesUniversity of Chinese Academy of SciencesBeijing100049China Southern Marine Science and Engineering Guangdong Laboratory(Zhuhai) Zhuhai519080China Beijing Yanshan earth Critical Zone National Research Station Beijing101408China

China has planned and built several world-class cascade high dams in Jinsha River,Dadu River,Lancang River,and Yarlung Zangbo *** complex geological conditions in the reservoir area and numerous large-scale landslide bodies make the potential disaster risk of overflowing and cascade dam failure caused by landslide-generated tsunami under increasing severe ***,the study on describing and predicting the complex dynamic processes of generation,propagation,overflowing,wave setup,and the interaction between tsunami and lakeshore has not been systematically carried *** on the high-order Boussinesq-type equations,the development of the dynamic system of tsunamis in lakes coupled with the landslide process is realized using the finite volume method in this *** verify the accuracy and reliability of the study,the Xiluodu Reservoir is selected as the object to simulate the potential landslide-generated *** factors such as the generation and propagation of tsunamis,dam overflowing,and wave setup in the downstream river are quantitatively evaluated and *** constructed landslide with a total volume of 24×10^(6)m^(3)generates a near-field wave amplitude of about 28 *** maximum wave run-up height is about 95 m,the volume of the dam overflowing water up to 2.13×10^(6)m^(3),and the maximum wave height above the dam crest presents an M-shaped *** LGWs event raises the downstream water level by nearly 40 *** results show that the risk of landslide-generated tsunamis in the reservoir area in China cannot be *** developed Boussinesq-type equations coupled with the landslide dynamics can simulate the whole process of generation,propagation,runup,and estimating the overflowing water volume of the tsunamis in the lake,laying a foundation for the quantitative risk assessment of tsunamis in lakes of high cascade dams in China.

关键词： Tsunamis in lakes Landslide-generated tsunamis Boussinesq-type equations Numerical modeling The Xiluodu Reservoir

Effects of Crustal Eclogitization on Plate Subduction/Collision Dynamics: Implications for India-Asia Collision

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Journal of earth Science 2016年第5期27卷 727-739页

作者： Pengpeng Huangfu Yuejun Wang Zhonghai Li Weiming Fan Yan Zhang State Key Laboratory of Isotope Geochemistry Guangzhou Institute of Geochemistry Chinese Academy of Sciences Key Laboratory of computational Geodynamics College of Earth Sciences University of Chinese Academy of Sciences School of earth Science and Geological Engineering Sun Yat-Sen University CAS Center for Excellence in Tibetan Plateau earth sciences Key Laboratory of Continental Collision and Plateau UpliftInstitute of Tibetan Plateau Research Chinese Academy of Sciences

2D thermo-mechanical models are constructed to investigate the effects of oceanic and continental crustal eclogitization on plate dynamics at three successive stages of oceanic subduction, slab breakoff, and continental subduction. Crustal eclogitization directly increases the average slab density and accordingly the slab pull force, which makes the slab subduct deeply and steeply. Numerical results demonstrate that the duration time from initial continental collision to slab breakoff largely depends on the slab pull force. Specifically, eclogitization of subducted crust can greatly decrease the duration time, but increase the breakoff depth. The detachment of oceanic slab from the pro-continental lithosphere is accompanied with obvious exhumation of the subducted continental crust and a sharp uplift of the collision zone in response to the disappearance of downward drag force and the induced asthenospheric upwelling, especially under the condition of no or incomplete crustal eclogitization. During continental subduction, the slab dip angle is strongly correlated with eclogitization of subducted continental lower crust, which regulates the slab buoyancy nature. Our model results can provide several important implications for the Himalayan-Tibetan collision zone. For example, it is possible that the lateral variations in the degree of eclogitization of the subducted Indian crust might to some extent contribute to the lateral variations of subduction angle along the Himalayan orogenic belt. Moreover, the accumulation of highly radiogenic sediments and upper continental crustal materials at the active margin in combination with the strong shear heating due to continuous continental subduction together cause rising of isotherms in the accretionary wedge, which facilitate the development of crustal partial melting and metamorphism.

关键词： numerical modeling crustal eclogitization oceanic subduction slab breakoff continen-tal subduction Himalayan-Tibetan collision zone.

A unified theory for sharp dissolution front propagation inchemical dissolution of fluid-saturated porous rocks

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Science China(Technological sciences) 2019年第1期62卷 163-174页

作者： ZHAO ChongBin HOBBS Bruce ORD Alison computational Geosciences Research Centre Central South University School of earth and Environment The University of Western Australia

This paper presents a unified theory to deal with when, why and how a sharp acidization dissolution front(ADF), which is represented by the porosity distribution curve, can take place in an acidization dissolution system composed of fluid-saturated porous rocks. The theory contains the following main points:(1) A reaction rate of infinity alone can lead to a sharp ADF of the Stefan-type in the acidization dissolution system. This sharp front is unstable when permeability in the downstream region is smaller than that in the upstream region.(2) For a finite reaction rate, when the acid dissolution capacity number approaches zero,the ADF can have a sharp profile of the Stefan-type either on a much smaller time scale or on a much larger time scale than the dissolution time scale. In the former case, the ADF may become unstable on a much larger time scale than the transport time scale, while in the latter case, it may become unstable if the growth rate of a small perturbation is greater than zero.(3) On the dissolution time scale, even if both the reaction rate is finite and the acid dissolution capacity number approaches zero, the profile of an ADF may not be sharp because it is in a transient state. In this case, not only can an ADF change its profile with time, but also its morphology can grow if the growth rate of a small perturbation is greater than zero. Due to the involvement of both the change rate and the growth rate of the ADF profile, it is necessary to conduct a transient linear stability analysis for determining whether or not a time-dependent ADF is stable in the acidization dissolution system.

关键词： sharp dissolution front stationary/steady state transient state acid dissolution capacity acidization dissolution porous rocks

Submicron size-scale mapping of carbonate effective elastic properties from FIB-SEM images and finite element method

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Science China earth sciences 2017年第3期60卷 557-575页

作者： CHENG HuiHong ZHU BoJing David A YUEN SHI YaoLin Key Laboratory of computational Geodynamics of Chinese Academy of sciences Beijing 100049China College of earth Science University of Chinese Academy of SciencesBeijing 100049China Yunnan Observatories Chinese Academy of SciencesKunming 650216China Rock Mechanics and Carbon Store Lab Department of Earth SciencesDurham UniversityDurhamDH13LEUK Department of earth Science and Minnesota Supercomputing Institute University of MinnesotaMinneapolis 55455USA

In this paper, an automatic unstructured focused ion beam （FIB） and scanning electron microscopy （SEM） images induced representative volume element （RVE） finite element （FE） method is developed to predict submicron scale carbonate rock effective Young＇s and bulk moduli and Poisson＇s ratio on parallel CPU-GPU platform. Based on high resolution-contrast surface morphology and internal fabric-texture structure images from carbonate rock specimen （covered 0.12-64 μm2 area and 8000 μm3 domain）, the cubic RVE FE models are constructed from different sites through Avizo with user-defined parameters Matlab coding. The effective Young＇s and bulk moduli and Poisson＇s ratio of the different RVEs and porosity and pore size are computed by using periodic boundary condition in the well-known FE software Abaqus. FE mesh sensitivity analysis has been conducted where all moduli converge to a certain constant value at larger FE mesh density. The effect of fabric-texture （pore size, shape, and distribution） on the elastic properties is discussed. The correlations between the computed effective elastic properties and pore size, porosity, RVE size have been established. The simulation results show that the effective Young＇s and bulk moduli and Poisson＇s ratio have strong anisotropic behavior and depend on RVE size, porosity and pore size. The RVE size, porosity and pore size are three independent factors in affecting of the effective elastic moduli, the effect mechanism of porosity and pore size is same while the effect mechanism of RVE size is difference.

关键词： Carbonate effective elastic properties Finite element analysis Focused ion beam Nano-porosity Nano pore size

Finite element analysis of steep excavation slope failure by CFS theory

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earthquake Science 2012年第2期25卷 177-185页

作者： Huihong Cheng Huai Zhang Bojing Zhu Yaolin Shi Key Laboratory of computational Geodynamics Chinese Academy of SciencesBeijing 100049China College of earth sciences Graduate University of Chinese Academy of SciencesBeijing 100049China

The distribution of Coulomb failure stress （CFS） change in the steep excavation slope is calculated by finite element method in this paper, and the failure mechanics under different conditions have been investigated. Comparing the CFSs before and after the slope excavation （stress loading and unloading processes）, the dangerous internal zone and the most likely failure external area are attained. Given the shear cracks on the top surface while tensile stress or cracks along the toe of the slope, we analyze the high cutting-angle steep slope in Kaixian county of the Three Gorges Reservoir region. We bring forward that the peak value of CFS after excavation can reach to the order of 0.1 MPa, which is greatly higher than that of before. Our preliminary results are useful for optimizing the reinforcement structure during the steep slope stabilization engineering.

关键词： Coulomb failure stress stabilization and failure evaluation steep slope excavation

Reefs in the Early Paleozoic Taebaek group,Korea:A Review

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Acta Geologica Sinica(English Edition) 2016年第1期90卷 352-367页

作者： LEE Jeong-Hyun HONG Jongsun WOO Jusun OH Jae-Ryong LEE Dong-Jin CHOH Suk-Joo Department of earth and Environmental sciences Korea University Department of earth and Planetary sciences University of Tennessee Division of Polar earth-System sciences Korea Polar Research Institute Department of earth and Environmental sciences Andong National University

Various early Paleozoic （Cambrian Series 3-Middle Ordovician） reefs are found in the Taebaek group, eastern Korea, located in the eastern margin of the Sino-Korean Block. They occur in every carbonate-dominant lithostratigraphic unit of the group, but their morphology and composition differ markedly. The Daegi Formation （middle Cambrian： Cambrian Series 3） contains siliceous sponge-Epiphyton reefs formed in a shallow subtidal environment, which is one of the earliest metazoan-bearing microbial reefs after the archaeocyath extinction. The Hwajeol Formation （upper Cambrian： Furongian） encloses sporadic dendrolites consisting of Angulocellularia, which developed in a relatively deep subtidal environment, representing a rare deeper water example. The onset of the Ordovician radiation resulted in the formation of microbialite-Archaeoscyphia-calathiid patch reefs in shallow subtidal deposits of the Lower Ordovician Dumugol Formation. Subsequent late Early Ordovician relative sea-level fall established extensive peritidal environments, forming microbial mats and stromatolites of the Lower-Middle Ordovician Makgol Formation. Ensuing Ordovician radiation resulted in one of the earliest metazoan skeletal reefs of the Middle Ordovician Duwibong Formation, constructed by stromatoporoid Cystostroma and bryozoan Nicholsonella, and developed around shallow shoals. These reefs reflect ongoing evolution and sea-level change during the early Paleozoic, and exemplify a rare glimpse of peri-Gondwanan records of reef evolution, which warrant detailed investigations and comparison with their counterparts in other regions.

关键词： carbonate sedimentology metazoans stromatolites Porifera Cambrian-Ordovician Taebaeksan Basin Korea