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Kinematics and dynamics of the Mesozoic orogeny and late-orogenic extensional collapse in the Sino-Mongolian border areas

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Science china Earth Sciences 2005年第7期48卷 849-862页

作者： zheng yadong 1.& wang tao2 1. key laboratory of orogenic belts and crustal evolution (Peking University),{1., Beijing 1.0871. china 2. Institute of Geology, Chinese Academy of Geological Sciences, Beijing 1.0037, china key {1. of orogenic belts and crustal evolution (Peking University) Ministry of Education Beijing 100871 China Institute of Geology Chinese Academy of Geological Sciences Beijinq 100037 China

The Sino-Mongolian border areas underwent two important tectonic events during Mesozoic time after late Paleozoic orogeny: a late Triassic to earlier Jurassic contractional event that resulted in a large-scale south-vergent thrust during the orogeny and a late Jurassic-earlier Cretaceous extensional event in a north-south direction that formed a metamorphic core complex. The kinematic and dynamic analyses show that the thrust sheet moved southwards with a kinematic vorticity number of ca. -0.1. and sub-horizontal maximum compressive stress axis that belongs to a contraction-thickening shear. The upper plate of the late-orogenic detachment relatively moved in a 1.5°direction. The average kinematic vorticity in its earlier stage was 0.74 that belongs to simple shear dominated shearing and related to the maximum compressive stress axes dipping at ～66°, while the later average kinematic vorticity was ～0.55°that belongs to pure shear dominated shearing with sub-vertical maximum compressive stress axes. This suggests that the thrusting led to the crust thickened and the lower plate rocks that were originally located in the upper crust depressed through a brittle-ductile transition zone into the lower crust and became warmer. The heated rocks trended to uplift since their increasing volume and decreasing density while the loading of the upper-plate rocks increased due to the structural thickening. Under the combined effect of the loading and the thermal-uplifting, the ductile shear zone in between increased in its component of vertical pure shear. Once its pure-shear component exceeded its simple-shear one the ductile shear zone became an extension-thinned shear zone. This progressive transitional process reflects internal and essential temporal and spatial relationships: the extensional factor nucleated during the crust thickening by thrusting and increase of the extensional factor finally led to late-orogenic collapse.

关键词： Mesozoic thrusting,late-orogenic collapse,kinematic vorticity number,stress state.

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A challenge to the concept of slip-lines in extrusion tectonics

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Geoscience Frontiers 2011年第1期2卷 23-34页

作者： yadong zheng~(a,*),Erchie wang~b,Jinjiang Zhang~a,tao wang~c a key laboratory of orogenic belts and crustal evolution,ministry of education,School of Earth and Space Sciences, Peking University,Beijing 1.0871.china b Institute of Geology and Geophysics,Chinese Academy of Sciences,Beijing 100029,china c Institute of Geology,Chinese Academy of Geological Sciences,Beijing 100037,china [a] key {1. of orogenic belts crustal {1. Ministry of Education School of Earth Space Sciences Peking University Beijing 100871 China [b] Institute of Geology Geophysics Chinese Academy of Sciences Beijing 100029 China [c] Institute of Geology Chinese Academy of Geological Sciences Beijing 100037 China

Wide-open V-shaped conjugate strike-slip faults in Asia are typically related to extrusion ***,the tectonic model based on the slip-line theory of plasticity has some critical problems associated with *** conjugate sets of slip-lines in plane deformation,according to the theory of plasticity should be normal to each another but,in reality,the angles between the conjugate strike-slip faults,which are regarded as slip-lines in extrusion tectonics in the eastern Mediterranean,Tibet-middle Asia,china and the Indochina Peninsular regions,are always more than 90°(on average～1.0°) in the direction of contraction. Another problem is that the slip-line theory fails to explain how,in some cases,e.g.,in the Anatolian area in the eastern Mediterranean,the extrusion rate is much higher than the indent *** two major problems are easy to solve in terms of the Maximum-Effective-Moment(MEM) Criterion that predicts that orientations of the shear zones are theoretically at an angle of 54.7°and practically at angles of 55°±1.°with theσ- or contractional *** orientations of the strike-slip faults that accommodate extrusion tectonics are,therefore, fundamentally controlled by the MEM *** extrusion is along the MEM-orientations,the extruding rate is normally higher than the indenting rate.

关键词： Extrusion tectonics Slip-line Wide-open V-shaped strike-slip faults MEM-Criterion Strain rate

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On the material invariant of 1.0°-conjugate angle of shear bands——Reply to Gomez-Rivas and Griera(201.)

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Science china Earth Sciences 2015年第12期58卷 2363-2368,1-3页

作者： zheng {1. ZHANG JinJiang wang tao The key {1. of orogenic belts and crustal evolution Ministry of Education School of Earth and Space SciencesPeking University Institute of Geology Chinese Academy of Geological Sciences

After their experimental data were re-explained in terms of the maximum-effective-moment （MEM） criterion, Gomez-Rivas and Griera （201.） challenge the validity of the MEM-Criterion in terms of shear fractures, which have mixed up with shear fractures and shear bands. The two features are similar in appearance but different in deformation mechanism （s）. The MEM-criterion proves that ±55° to σ1.ra are the maximum effective moment directions and the shear bands that formed by mate- rial-line （beddings or fabrics） rotation mechanism have a constant conjugate angle of 1.0°. Theoretically, the 55° or 1.0° is a material-invariant, and practically, a statistic-invariant or preferred direction with average deviation of -1.°. By this angle, shear bands can be easily recognized from shear fractures with conjugate angle never over 90°. The High-strain deformation in the lozenges usually predates the surrounding shear bands. Two stress states can not coexisted simultaneously in the same place and the resolving cr1. normal to the related shear zone represents 0-1.0% deformation partitioning, depending on the original kinematic vorticity of the shear zones.

关键词： kink-bands/shear bands deformation localization MEM-criterion deformation partitioning

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Interpretation of the experimental data provided by Gómez-Rivas and Griera(201.) in terms of the MEM-criterion

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Science china Earth Sciences 2014年第11期57卷 2819-2824页

The systematical experiments carried out by G6mez-Rivas and Griera （201.） demonstrate that the ductile shear zones initiate at 55° to 0-1.just as predicted by the MEM-criterion. However, the data are explained in terms of dilatancy, which requires many prerequisites and implies that the ±55° angle is only valid for the used material. In contrast, the -55°predicted by the MEM-criterion is material independent, which makes it widely applicable to explaining the development of ductile shear zones in nature.

关键词： MEM-criterion initiate conjugate angle deformation localization

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The Maximum Effective Moment Criterion (MEMC) and Its Implications in Structural Geology

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Acta Geologica Sinica(English Edition) 2006年第1期80卷 70-78页

作者： zheng {1. wang tao wang Xinshe The key {1. of orogenic belts and crustal evolution School of Earth and Space Sciences Peking University Beijing 100871 Institute of Geology Chinese Academy of Geological Sciences Beijing 100037

The MohroCoulomb criterion has been widely used to explain formation of fractures. However, it fails to explain large strain deformation that widely occurs in nature. There is presently a new theory, the MEMC, which is mathematically expressed as Meff = （（σ1.σ3） *** 2α sin α）/2, where σ1.σ3 represents the yield strength of the related rock, L is a unit length and a is the angle between σ1.and deformation bands. This criterion demonstrates that the maximum value appears at angles of ±54.7° to σ1.and there is a slight difference in the moment in the range of 55°±1.°. The range covers the whole observations available from nature and experiments. Its major implications include：（1. it can be used to determine the stress state when the related deformation features formed; （2） it provides a new approach to determine the Wk of the related ductile shear zone if only the ratio of the vorticity and strain rate remains fixed; （3） It can be used to explain （a） the obtuse angle in the contraction direction of conjugate kink-bands and extensional crenulation cleavages, （b） formation of low-angle normal faults and high-angle reverse faults, （c） lozenge ductile shear zones in basement terranes, （d） some crocodile structures in seismic profiles and （e） detachment folds in foreland basins.

关键词： maximum effective moment criterion crenulation cleavage low-angle normal fault high-angle reverse fault crocodile structure lozenge structure detachment fold

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Diagenesis and Metamorphism of Triassic Flysch Along Profile Zoige-Lushan,Northwest Sichuan,china

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Acta Geologica Sinica(English Edition) 2008年第4期82卷 917-926页

作者： wang Hejing M. RAHN {1. Xiaofeng zheng Nan XU Tingjing key {1. of orogenic belts and crustal evolution Ministry of Education China School of Earth and Space Sciences Peking University Beijing 100871 China Hauptabteilung fiir die Sicherheit der Kernanlagen 5232 Villigen-HSK Switzerland College of Earth Sciences Chengdu University of Technology Chengdu 610059 China

We used illite and chlorite crystaHinities, index minerals, mineral assemblages, polytype and domain size of white mica, electron microprobe analysis （EMPA）, b0 geobarometer and chlorite geothermometer to quantify the diagenetic and metamorphic overprint on the Triassic flysch formations in the Songpan-Garze orogen along profile Zoige-Lushan, northwest Sichuan. Two anchizones, two epizones, one diagenetic zone and a transition belt in-between them are defined on the basis of the obtained data. lllite crystallinity correlates strongly with the best mean domain size of mica and moderately with chlorite crystallinity. 2M1.white mica polytype are observed within the epizone whilst 2M1.and 1. polytypes occur in the anchizone and diagenetic zone. Epizonal metamorphism reached maximum temperatures of 370℃±21. at low-to intermediate pressure conditions. Clay minerals underwent Ostwald ripening during metamorphism. Rocks from both sides of the Longmenshan fault reveal contrasting degrees of metamorphic overprint： on the northwest side of the Longmenshan fault, epimetamorphic conditions contrast with diagenetic rocks on the southeast side.

关键词： diagenesis metamorphism Songpan-Garze orogen Triassic flysch illite crystallinity,Longmenshan fault

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Age assignment of the Upper Carboniferous Arbasay Formation in Shichang Region,North Tianshan(NW china)

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Journal of Palaeogeography 2018年第3期7卷 272-282页

作者： Jia-Lin wang Chao-Dong Wu Xi Jiang Wen Zhu Jun Wu Jun wang Meng-Lin zheng key {1. of orogenic belts and crustal evolution Ministry of Education School of Earth and Space Sciences Peking University Institute of Oil & Gas Peking University Department of Xinjiang Exploration Project Management Smopec Shengli Oilfield Company Research Institute of Exploration and Development Xinjiang Oilfield CompanyPetro China

The North Tianshan orogenic Belt contains the youngest ophiolites in the Tianshan and provides some information on timing of the last closure of the Junggar-Balkhash Ocean. LA-ICP-MS zircon U-Pb dating was conducted to define the formation age of the Arbasay Formation in the Shichang Region of North Tianshan, which is exposed near the suture zone but its age remains debated. The Arbasay Formation is mainly composed of volcanic and volcaniclastic rocks with tuft interlayers. The zircons from the tufts yield two age populations of 31. ± 3 Ma and 304 ± 2 Ma, constraining the commencement and demise timings of volcanism, respectively. Furthermore, zircon U-Pb age spectra of the tuffaceous sandstones display the youngest peak age at 308 Ma, indicating a 〈 308 Ma age for the depositional age of volcaniclastic rocks. The volcaniclastic rocks therefore were likely to deposit together with the syn-sedimentary volcanism during Late Carboniferous. This means that the Arbasay Formation in Shichang Region should be re-assigned to Late Carboniferous in age. Given that the Arbasay Formation was likely to be formed during the tectonic transition from compression to extension, the Junggar-Balkhash Ocean possibly closed during Late Carboniferous.

关键词： Xinjiang LA-ICP-MS zircon U-Pb dating Stratigraphic age Volcaniclastic rock Junggar-Balkhash Ocean

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水热金刚石压腔结合拉曼光谱技术进行Na2SO4-水体系溶解结晶动力学研究

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光谱学与光谱分析 2019年第12期39卷 3698-3704页

作者：王世霞杨梦吴嘉郑海飞上海理工大学理学院上海200093 中国石油大学(北京)油气资源与探测国家重点实验室北京102249 北京大学造山带与地壳演化教育部重点实验室北京100871

成矿作用过程中,温压条件改变导致矿物溶解重结晶,溶液中溶质浓度发生变化。从溶液中析出晶体的粒度同时存在着时间和空间的分布,是复杂的动力学过程。当前对矿物在流体中溶解重结晶动力学研究主要使用高压釜或活塞圆筒等封闭设备测定... 详细信息

成矿作用过程中,温压条件改变导致矿物溶解重结晶,溶液中溶质浓度发生变化。从溶液中析出晶体的粒度同时存在着时间和空间的分布,是复杂的动力学过程。当前对矿物在流体中溶解重结晶动力学研究主要使用高压釜或活塞圆筒等封闭设备测定溶液溶质浓度的变化或固相矿物的形态变化,降温淬火反应会影响样品的真实组成。使用可进行原位观测的金刚石压腔结合拉曼光谱分析技术,研究无水芒硝-饱和Na2SO4溶液随体系温度压力变化所出现的晶体溶解重结晶过程。通过原位观测无水芒硝溶解、结晶变化来探究硫酸钠晶体在不同温压条件下的溶解结晶动力学反应机制。结果表明常温条件下无水芒硝拉曼位移分别位于449.9, 620.5, 632.9, 647.4, 993.3, 1.1.1.8, 1.1.2.2和1.1.3.1.cm^-1.随着体系温度的缓慢升高,固相Na2SO4的晶形不断发生变化,温度至1.3℃时无水芒硝(Na2SO4)完全溶解,降温重结晶出现了新的1.1.6.5 cm-1.曼特征峰,重结晶晶体为芒硝(Na2SO4·1.H2O);金刚石原位观测结果显示迅速升温过程中无水芒硝发生部分溶解重结晶,重结晶区域拉曼特征峰显示依然为无水芒硝。拉曼光谱定量分析结果显示,溶液中SO42-,H2O的拉曼谱峰面积比值参数更能反映SO4^2-浓度的变化,体系达到溶解重结晶平衡状态时, SO4^2-/H2O峰面积比值AR为(0.01. 6±0.000 4),误差为2.4%。应用Johnson-Mehl-Avrami-Kolmogorov(JMAK)模型结合溶液中SO4^2-/H2O峰面积比值变化对体系中固相无水Na2SO4的溶解重结晶过程进行动力学拟合,计算得出无水硫酸钠在1.9℃条件下的溶解结晶反应的反应级数为1.266 7,反应平衡常数为0.001.26。综上所述,水热金刚石压腔装置实验步骤少,过程简便,可避免由于淬火过程中退化交换作用等造成的误差,应用水热金刚石压腔原位观测的装置优势结合拉曼光谱定量分析技术可实现高温高压条件下矿物在水溶液中溶解结晶动力学过程的原位观察和测定,是一种高效的动力学研究手段。

关键词： HDAC 高温高压拉曼光谱 Na2SO4^-水体系溶解重结晶动力学

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鲜水河断裂带乾宁段晚第四纪走滑速率及区域强震危险性研究

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地质学报 2022年第7期96卷 2312-2332页

作者：白明坤 Chevalier Marie-Luce 李海兵潘家伟吴琼王世广刘富财焦利青张进江张蕾龚正中国地质科学院地质研究所自然资源部深地动力学重点实验室北京100037 北京大学地球与空间科学学院教育部造山带与地壳演化重点实验室北京100871 南方海洋科学与工程广东省实验室(广州) 广东广州511458 国家自然灾害防治研究院中国应急管理部北京100085 中国地质科学院地球深部探测中心北京100037 中国地震局地球物理研究所北京100081

活动断裂几何学特征及滑动速率是研究断裂运动学、动力学机制及其评估区域强震危险性的重要依据。青藏高原东缘左行走滑的鲜水河断裂带是控制高原物质向南东挤出的重要边界,是中国陆内活动性最强的断裂之一。本文以鲜水河断裂带北西段... 详细信息

活动断裂几何学特征及滑动速率是研究断裂运动学、动力学机制及其评估区域强震危险性的重要依据。青藏高原东缘左行走滑的鲜水河断裂带是控制高原物质向南东挤出的重要边界,是中国陆内活动性最强的断裂之一。本文以鲜水河断裂带北西段为研究对象,通过高精度遥感影像解译、野外考察、OSL(光释光)和^(1.)C测年方法以及LiDAR(激光雷达)扫描获得乾宁段龙灯乡冲积阶地的位错量和废弃年龄。T4和T3′水平位错量分别为1.6±5 m和77±2 m,T4阶地垂直位错量为9.6±0.5 m。T4和T3′阶地的废弃年龄分别为1.±1.ka和7±1.ka。结合对应的年龄和位错量,得到乾宁段晚第四纪走滑速率左行走滑速率为1..5±1.mm/a,垂直滑动速率为0.9±0.1.mm/a,断层倾向北东,具有正断运动学特征。通过重新计算断裂两侧GPS矢量沿断裂方向分量,得到鲜水河断裂带炉霍段、炉霍—康定段、磨西段现今左行走滑速率分别约为8.1.mm/a、8.2 mm/a、9.4 mm/a,整体表现为自北西向南东递增。综合乾宁段晚第四纪走滑速率和最新强震活动的离逝时间估算,认为鲜水河断裂带乾宁段目前应变累积达到了发生一次M_(W) 6.8(M_(S) 7.2)大地震的潜能,在区域防震减灾工作中应对此加以重视。

关键词：青藏高原东缘鲜水河断裂带北西段构造地貌学晚第四纪滑动速率地震危险性

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