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This study focuses on coalbed methane (CBM) wells in high-ranking coal seam as the research subject. Considering the influence of effective stress and matrix shrinkage, a comprehensive permeability calculation model for CBM reservoirs is established. Based on this model, the variations in pressure and permeability during well production are quantified. By integrating static geological parameters, a finely classified classification of CBM wells is achieved using self-organizing map (SOM) neural network. Subsequently, an analysis of production dynamic characteristics and productivity differences among different types of CBM wells is performed, followed by providing drainage optimization suggestions. The results of SOM analysis show that 7,000 m3/d and 1,500 m3/d can be used as the production boundaries for the wells with different productivity in Block P. The daily gas production of exceptional well exceeds 7,000 m3/d, and the permeability remains relatively stable throughout the drainage process of this well. The daily gas production of the potential well ranges from 1,500 to 7,000 m3/d, and the permeability exhibits a significant decrease during the drainage process. The daily gas production of Inefficient well is consistently below 1,500 m3/d with moderate permeability variation. In addition to well location and structural geology, production variability is also influenced by the matching of reservoir conditions and drainage systems. This is primarily manifested in discontinuous drainage systems and rapid decline in bottom hole pressure (BHP) during early production. The analysis of drainage parameters indicates that in order to achieve optimal production from CBM wells, the BHP should exhibit an initial rapid decline followed by a slowly decrease during the early production period, with an average pressure drop ranging from 0.005 to 0.02 MPa/d. The research findings can offer technical guidance for the future advancement of CBM in the P Block. [ABSTRACT FROM AUTHOR]

Tamusu area in Inner Mongolia is a candidate site for the first clay rock repository in China. Comprehensive analyses conducted on stratigraphic characteristics, mineralogy, structural geology, and three-dimensional geological modeling in the Tamusu area showed that: the thickness of clay rock is more than 200 m with burial depth ranging from 200 to 800 m, which is mainly composed of zeolite, dolomite, and illite. Fractures are not well developed and the tectonic environment is stable. Additionally, the terrain and landform are relatively flat and desolate. These findings suggest that the Tamusu area presents favorable geological conditions for the construction and operation of a high-level radioactive waste repository. [ABSTRACT FROM AUTHOR]

The part of China, east of the Hu Huanyong Line, is commonly referred to as eastern China. It is characterized by a high population density and a well-developed economy; it also has huge energy demands. This study assesses and promotes the large-scale development of geothermal resources in eastern China by analyzing deep geological structures, geothermal regimes, and typical geothermal systems. These analyses are based on data collected from geotectology, deep geophysics, geothermics, structural geology, and petrology. Determining the distribution patterns of intermediate-to-deep geothermal resources in the region helps develop prospects for their exploitation and utilization. Eastern China hosts superimposed layers of rocks from three major, global tectonic domainsd namely Paleo-Asian, Circum-Pacific, and Tethyan rocks. The structure of its crust and mantle exhibits a special flyover pattern, with basins and mountains as well as well-spaced uplifts and depressions alternatively on top. The lithosphere in Northeast China and North China is characterized by a thin, low density crust and mantle, whereas the lithosphere in South China has a thin, low density crust and a thick, high density mantle. The middle and upper crust contain geobodies with high conductivity and low velocity, with varying degrees of development that create favorable conditions for the formation and enrichment of geothermal resources. Moderate-to-high temperature geothermal resources are distributed in the MesozoiceCenozoic basins in eastern China, although moderate temperature geothermal resources with low abundance dominate. Porous sandstone reservoirs, karstified fractured-vuggy carbonate reservoirs, and fissured granite reservoirs are the main types of geothermal reservoirs in this region. Under the currently available technical conditions, the exploitation and utilization of geothermal resources in eastern China favor direct utilization over large-scale geothermal power generation. In Northeast China and North China, geothermal resources could be applied for large-scale geothermal heating purposes; geothermal heating could be applied during winter along parts of the Yangtze River while geothermal cooling would be more suitable for summer there; geothermal cooling could also be applied to much of South China. Geothermal resources can also be applied to high value-added industries, to aid agricultural practices, and for tourism. [ABSTRACT FROM AUTHOR]

• BIFs ores formed in a hydrothermal-related volcanic submarine environment. • BIFs deposited from seafloor hydrothermal fluids in partially oxidized seawater. • A mantle plume model explains the formation of the late Neoarchean Qian'an BIFs in NCC. The Neoarchean Qian'an BIF deposit in eastern Hebei, eastern North China Craton has attracted extensive attention of study in the last decades, but the genesis, e.g., Fe sources, metallogenic mechanism, as well as tectonic attributes of the BIFs remains highly disputed. Based on field investigations, microscopic observations and geochemical analysis, this study tries to unravel the source characteristics of ore-forming materials in the Qian'an deposit. The results show that the chemical compositions of the BIF ore samples are mainly composed of TFe 2 O 3 and SiO 2 , with minor Al 2 O 3 and TiO 2. The total trace element contents of the samples are relatively low. The PAAS-normalized REE distribution patterns of the ores show LREE depletion and HREE enrichment, with robust positive anomalies of Eu, Y and La. These characteristics indicate that the BIFs are attributed to dominant chemical precipitation originated from paleo-ocean with obvious volcanic hydrothermal contributions and minor clastic input. Their positive to no Ce anomalies and positive δ56Fe magnetite values unveil that the iron was precipitated at low oxygen fugacity. These results, in collaboration with evidence from previous lithological, structural geology, metamorphic P-T paths, geochemistry, geochronology and numerical modeling studies, support a mantle plume model to explain the complicated tectono-thermal processes, and the sources of BIFs in Eastern Hebei, eastern North China Craton. [ABSTRACT FROM AUTHOR]

We combine a ∼485 km‐long seismic reflection profile and a S‐wave speed transect from surface‐wave tomography, to reveal the lithospheric deformation mode of the intracontinental Qinling orogeny, central China. We observe a thick lithosphere keel in the convergence zone between the Yangtze Block and the North China Craton (NCC) and a shallow‐crustal (8–15 km depth) décollement that extends into the lower crust of the Qinling Orogen. Combining with surface structural geology and magmatism, we interpret these seismic findings as kinematically linked features formed by renewed intracontinental convergence between the NCC and the Yangtze Block in the late Mesozoic. We highlight that the ∼40 km lithospheric thickening in the convergence zone was likely balanced by > 130 km thin‐skinned crustal shortening along a crustal‐scale strain‐transfer décollement, and was responsible for the occurrence of late Mesozoic magmatism (∼160–100 Ma) at the southern edge of the NCC. Plain Language Summary: Here we reveal the lithospheric deformation mode of the intracontinental Qinling orogeny, central China, through a seismic reflection profile and a S‐wave speed transect from surface‐wave tomography. Our results suggest a thick lithosphere keel in the convergence zone between the Yangtze Block and the North China Craton (NCC), and a shallow‐crustal (8–15 km depth) décollement that extends into the lower crust of the Qinling Orogen. Coupled with published surface data, we suggest that these seismic findings document the lithospheric deformation induced by late Mesozoic intracontinental convergence between the NCC and the Yangtze Block. It appears that the ∼40 km lithospheric thickening was balanced by >130 km thin‐skinned crustal shortening along a long‐distance strain‐transfer décollement. Key Points: We reveal the lithospheric deformation mode of the intracontinental Qinling orogeny, central ChinaThe ∼40 km lithospheric thickening was likely balanced by >130 km thin‐skinned crustal shorteningThe long‐distance strain‐transfer décollement plays a vital role in accommodating the crustal shortening and lithospheric thickening [ABSTRACT FROM AUTHOR]

This research investigates small-scale tectonic activity in the Jiujing region in Beishan, northwest China through the application of persistent scatterer (PS) Interferometric synthetic aperture radar (InSAR). PS InSAR is an effective monitoring tool in this unpopulated, arid, and unvegetated rural area, whose surface geology is dominated by a single large granitic intrusion, and which represents a candidate site for a geological disposal facility (GDF) for high-level radioactive waste (HLW) in China. This research demonstrates that faults F16-2, F17, F18, and F20-2 are still active, producing dip-slip motions along the fault planes. The lithological variations in weathering and erosion can be discounted as the cause for these small-scale displacement variations. The work has also identified 11 previously unknown faults, characterising them from vertical (DU) and eastward horizontal (DE) displacements along and across the faults. These newly discovered structures demonstrate how PS InSAR can be used to monitor and measure micro-scale movements on regional-scale faults, which, in many cases, were previously considered to be inactive. Thus, this also improves our understanding of local stress regimes in this area. The Jiujing region is part of a convergent fault zone dominated by NE-SW compression, leading to NE-SW crustal shortening and NW-SE elongation. Through determination of the sense of ground movement measured at irregularly distributed PS points, some faults are reverse and trending NW-SE, while others are normal and trending NE-SW, highlighting how InSAR can be used to resolve fault type and relative movements to monitor tectonic fault blocks at a regional scale. [ABSTRACT FROM AUTHOR]

The Shijiutuo Uplift within the Bohai Bay Basin(BBB)has experienced a complex evolutionary history since the Cenozoic. Studies of the Cenozoic evolution of the Shijiutuo Uplift are important for basin tectonics and petroleum geology. The formation of uplifts in rift basins is generally controlled by regional tectonic event and fault-block tilting. In this study, apatite fission track (AFT) data from fourteen samples and seismic data analysis were used to study the processes of regional uplift and fault-block tilting. We further investigated the Cenozoic evolution and formation mechanism of the Shijiutuo Uplift. The results indicated that the Shijiutuo Uplift experienced a two-phase differential tectonic uplift and erosion history (1) Widespread rapid uplift and erosion during the early Cenozoic (65–55 Ma) (2) Widespread uplift and erosion from 40 Ma to 16 Ma. The uplift and erosion substages of 40–38 Ma and 26–16 Ma were mainly caused by regional uplift, whereas those of 38–26 Ma resulted from fault-block tilting. Since the end of the third member from the Eocene Shahejie Formation, the Shijiutuo Uplift began to rise, causing the greater Bozhong Depression to be separated into the independent Qinnan and Bozhong Sags. These tectonic uplift and erosion events have a wide range of responses and regional dynamics in eastern China. The findings of this study will lead to a better understanding of the evolution and formation of uplifts within the BBB. [Display omitted] • The Shijiutuo Uplift underwent two stages of tectonic uplift and erosion events in the Cenozoic. • Formation of the Shijiutuo Uplift was associated with regional uplift and fault-block tilting. • The Shijiutuo Uplift did not exist before the end of the third member from the Eocene Shahejie Formation. • The tectonic uplift and erosion events had a wide response in eastern China. [ABSTRACT FROM AUTHOR]

Fault slip rates are critical to quantify continental deformation. Those along the Karakax fault (northwestern Altyn Tagh Fault: ATF) have been debated, even though it is one of Tibet's most outstanding active faults. At Taersa, using LiDAR measurements of terrace and fan riser offsets (∼6 to ∼500 m) and 10Be/26Al dating of alluvial surfaces (<210 ka), we obtain a late Quaternary slip rate of ∼2.5 ± 0.5 mm/yr. This doubles the ∼2.6 ± 0.5 mm/yr rate time span found to the east and west. We interpret the ∼150 km‐long, free‐faced rupture along the fault to be that of the M ∼ 7.6 event felt in Hotan in 1882. Characteristic slip (∼6 m) during four large earthquakes since ∼10 ka implies a ∼2500 ± 500 years return time. A ∼3 mm/yr rate is consistent with the ∼80 km offset of the Karakax river since uplift of the West Kunlun range and sediment deposition in the Tarim foreland accelerated, ∼24 Ma ago. The faster slip rate (∼10.5 mm/yr) on the central ATF matches the sum of those along the reactivated West Tibetan terrane boundaries (Karakax and Longmu‐Gozha Co faults) at the Uzatagh triple junction (∼36°N, 83°E). The abrupt termination and altitude drop of the Karakorum range where the Longmu Co and Karakorum faults meet (Angmong junction), also reflect triple junction kinematics. Such localized changes account for the rise of the Karakorum and West Kunlun ranges and support lithospheric block tectonics rather than diffusely distributed deformation. Plain Language Summary: How the Tibetan plateau rose to ∼4500 m and deforms today remain outstanding questions. Tibet's northern edge follows the ∼2000 km‐long ATF, whose westernmost branch is the Karakax fault. Despite the spectacular escarpments and offsets observed along that fault, its slip rate, critical to quantify continental deformation, has remained controversial. Here, we corroborate that, for the last ∼210,000 years, that rate has been ∼2.5 ± 0.5 mm/yr, based on high‐resolution topography and dating of left‐laterally offset fluvial surfaces. The ∼80 km offset of the Karakax river implies that this rate may have remained constant since the rise of the Kunlun range above the Tarim basin started ∼24 Ma ago. The sharp fault trace reflects the exceptional preservation, since ∼10,000 years ago, of four M ∼ 7.6 earthquake ruptures (the last in 1882), each with ∼6 m of slip (∼2500 years return time). Fault slip rates, GPS vectors and mountain altitudes across western Tibet reflect block motions and triple junction kinematics rather than continuum deformation. Specifically, localized velocity changes appear to account for the rise of the West Kunlun and Karakorum ranges. Our results bridge the gaps between present and long‐term geological history, and broad‐scale geodesy and local field evidence. Key Points: The ∼400 km‐long, left‐lateral Karakax fault (western Altyn Tagh fault) slip rate has been ∼2.5 ± 0.5 mm/yr for ∼210 kaFour M ∼ 7.6 earthquakes (150 km rupture length; 2.5 ka return time) have offset Holocene terraces (6, 12, 18, and 24 m characteristic slip)Block tectonics and triple junction kinematics account for 24 Ma deformation of west Tibet and rise of ≥8000 m‐high Karakorum range [ABSTRACT FROM AUTHOR]

Core, well log and seismic data are used to investigate relationships between fan-delta facies architecture, basin margin morphology and sediment transportation into a deep-lacustrine environment of the Dongying Formation of Nanpu Sag, Bohai Bay Basin. The study interval is subdivided into two fan-delta dominant, third-order sequences of Stratasequence Paleogene Dongying Formation 1 (SQEd1) (younger) and Stratasequence Paleogene Dongying Formation 2 (SQEd2) (older). Fan-delta growth occurred in two stages with changing of facies architecture and morphology. During the early stage (SQEd2), the facies architecture is characterised by smaller and thin, channelised deposits, an extended mouth bar (delta-front sandy deposits) and slump/slides/flood turbidite dominated sandy deposits in the prodelta. However, during the late stage (SQEd1), the facies architecture is characterised by extended and thicker channelised deposit-dominated area, a local mouth bar (delta-front sandy deposits) and slump/slide-dominated sandy deposits in the prodelta. From the early to late stage, the delta morphology also changed with an upward increase in the delta-plain areal extent and delta-front gradient. Facies architecture variations indicate differences in sediment dispersal. The upward thickening and extending delta plain implies that more sediment was trapped in the proximal area owing to sufficient accommodation space generated by increasing boundary fault displacement. The upward increasing delta-front gradient resulted in differences in the type of prodelta/deep-lacustrine sandy deposits, while grainsize variations of the delta-front deposits affect the prodelta/deep-lacustrine sandy deposits. Boundary fault growth occurred with upward increasing displacement and length with the result that sediment supply outpaced accommodation-space creation and controlled the facies architecture changes. A two-stage fan delta developed with changing facies architecture is analysed. Facies architecture controlled fan-delta morphology with sediment transport into a deep-lacustrine area. Faults control the facies architecture and sand-rich deposit distribution. [ABSTRACT FROM AUTHOR]

Studies of Neoproterozoic granites near the western margin of the Yangtze Block provide new evidence on the mechanism leading to the Neoproterozoic break-up of the Rodinia Supercontinent. This contribution focusses on the structural geology, geochemistry, zircon U-Pb geochronology, and Hf-O isotope systematics of the poorly documented Mojiawan Monzogranite in the Kangding Complex, which gives us better constraints on the break-up of the supercontinent. Zircon U-Pb data show that two samples of the Mojiawan Monzogranite were emplaced during 797 ± 13 Ma and 785 ± 11 Ma (ca. 791 Ma). The granitic samples are Na-rich, calc-alkaline, peraluminous with A/CNK values of 1.13 and 1.25, and their zircons have positive εHf(t) values between +4.28 and +9.79 with crustal model ages TDM2 of 1424 to 1079 Ma, indicative of a juvenile source. The granitic samples also have low Rb/Sr and Rb/Ba ratios and high δ18O values of 5.42‰–8.97‰, consistent with derivation from the partial melting of the lower to middle crust. Combined with the geochemistry of other granitic plutons along the western margin of the Yangtze Block, we propose that the region records rifting at ca. 800 Ma due to the action of a mantle super-plume leading to the break-up of the Rodinia Supercontinent. [ABSTRACT FROM AUTHOR]

The western segment of the Main Tianshan shear zone (MTSZ) branches into three major dextral strike‐slip shear zones in the Borohoro Ranges, northwestern China. Mylonitic rocks within these zones exhibit vertical foliations, subhorizontal lineations, and dextral kinematics. The microstructures and CPO patterns of calcite and quartz in the tectonites suggest shearing at temperatures of 200°C to 500°C or above. The amount of dextral displacement along the zones is less than 100 km. LA‐ICP‐MS U‐Pb dating of zircons from some pre‐kinematic granites gave ages of 364–325 Ma and 316 Ma, and zircons from a syn‐kinematic leucogranite gave an age of 291 Ma. We propose that dextral shearing along the MTSZ started in the earliest Permian. Our data indicate that collision between the Yili and Junggar plates might have finished before 325 Ma or 316 Ma, with a tectonic transformation from 325 Ma to 300 Ma, resulting in intracontinental transpression from 300 Ma or 291 Ma. We suggest that the formation of the Kazakhstan orocline (KO) took place in two stages, with the early stage of bending driven by convergence related to oblique subduction, and the late stage possibly associated with lateral disarticulation as a result of the dextral strike‐slip shear zones. [ABSTRACT FROM AUTHOR]

Teleseismic body‐wave attenuation provides an independent constraint on the architecture of the lithosphere‐asthenosphere system. We obtain the first map of teleseismic attenuation across South China, which correlates well with previous estimates of lithospheric thickness. The weakest attenuation occurs in the Sichuan Basin, where continental lithosphere is thick, and in the adjacent Chuandian region, which we attribute to delaminated lithosphere, or lithosphere strengthened by an ancient plume based on comparison with previous studies. Smaller batches of remnant or delaminated lithosphere may cause local minima along the eastern coast. Pronounced negative anomalies occur in the Hengyang, Jianghan and Nanchang basins, motivating the hypothesis that the basins occur where locally strong blocks within the lithosphere resisted the pervasive deformation of South China. The strongest attenuation occurs in a broad region in the vicinity of the Hainan plume, which is consistent with high temperatures and possibly partial melt in the upper mantle. Plain Language Summary: As a classical intracontinental orogen, the detailed deformation of South China is a topic of broad interest. In this study, we present a teleseismic attenuation map based on 9,160 first‐arriving P phases from 82 deep teleseismic events that were recorded by the permanent seismic stations in South China. The attenuation is consistent with the lithospheric thickness revealed by previous results from seismic imaging, flexure modeling, and heat flow. In addition, the low attenuation in the Sichuan basin, Chuandian fragment and other basins, as well as high attenuation in Hainan Island are observed. Several other weaker local maxima require Qp values in the asthenosphere sufficiently low so as to be consistent with upwelling mantle, suggesting that small‐scale convection is pervasive across the region without causing significant volcanism at the surface. Combined with previous studies, the results support the occurrence of lithospheric dismemberment in Eastern China and provide an additional perspective on lithospheric strength and hot spot activity. Key Points: The attenuation in South China is obtained from teleseismic body wavesAttenuation suggests lithospheric thickness decreases from NW to SEHainan Island has a high attenuation in the mantle, consistent with a plume feature [ABSTRACT FROM AUTHOR]

Rock slope failures are controlled by a complex interplay of geological structures and anthropogenic activities. In this study, data from structural geology, rock mass characterization, and ground-based monitoring networks are integrated into a numerical model. This model is used to explore the relationships among structural features, damages, anthropogenic activities, and slope failures occurring on the Tibetan Plateau in China. In particular, a model for the interpretation of brittle tectonic structures is illustrated, which characterizes the fracture patterns and explains the role of these features in the development of rock slope instability. Additionally, the relationships between tectonic structure-related fractures and slope failure mechanisms are investigated by characterizing the rock mass damage using the geological strength index. Finally, a numerical model is developed, which integrates the available data. It is found that the tectonic structure-related fractures controlled by an anticline are primarily responsible for slope failure, while an excavation was identified as its triggering mechanism. This research can serve as a reference for studies on excavation-induced rockslides. [ABSTRACT FROM AUTHOR]

Beibuwan Basin is an important offshore oil and gas bearing basin of China. However, the distribution of oil and gas in different sags is uneven, and the rule of hydrocarbon accumulation and main controlling factors have not been clearly understood in this basin. Based on abundant seismic, well and analytical data, the differences and main controlling of tectonic evolution, sedimentary filling and source rock quality in sags are analyzed, and combined with the study of geothermal filed, the main controlling factors of differential hydrocarbon generation in sags of the Beibuwan Basin are clarified. On the basis of the research above, the hydrocarbon enrichment of the basin is clarified through the systematic analysis of reservoir‐caprock assemblage and accumulation characteristics of different structural units. The results show that there are four NE‐trending sag zones in the basin, and under the influence of fault activity, the scale of sags is regularly distributed. The scale of rifts in different sag zones decreases gradually from northwest to southeast and the scale of rifts in the middle of a single sag zone is normally larger than that at two ends. Under the control of the sag‐controlling faults activity, paleoproductivity and organic matter preservation conditions, the quality of source rocks in sags of the Beibuwan Basin decreases from northwest to southeast. The hydrocarbon‐rich sags in the Beibuwan Basin were formed under the control of source rocks and geothermal field, and the distribution of large‐medium scale fields is controlled by the favorable structural traps in the rift strata of inner gentle slope zone. The understanding of the hydrocarbon enrichment and main controlling factors in the Beibuwan Basin also provides a significant guidance for the oil and gas exploration in other rift basins. [ABSTRACT FROM AUTHOR]

BACKGROUND: At present, the application of new materials and new energy in vanous fields continues to deepen, and rare metal deposits have ushered in a worldwide upsurge of research and exploration. The Keketuohai rare metal deposit is the earliest developed deposit for rare metal mineral in China. However, the thermal infrared ( TIR) characteristics of minerals and rocks from this deposit have not been studied, which restricts remote sensing geological survey and relevant studies. OBJECTIVES: To analyze the characteristics of thermal infrared spectra of minerals and rock assemblages from the Keketuohai deposit, and provide the basic data for rare metal exploration. METHODS: A portable thermal infrared spectrometer was used to measure the spectrum data of typical minerals and rock assemblages of Keketuohai No. 3 vein. Data was analyzed using techtonics/ structural geology ( TSG) and related databases. RESULTS: Typical rare metal minerals like spodumene, lepidolite, beryl and tourmaline can be separated with TIR. Compared with lepidolite, there was a new diagnosed peak for the TIR spectrum of lepidolite - bearing pegmatite. The spectrum peaks of spodumene - bearing pegmatite and tourmaline - bearing pegmatite were significantly shorter than those of spodumene and tourmaline. However, the spectrum peaks of beryl - bearing pegmatite were shorter than the peaks of beryl. CONCLUSIONS: A database of thermal infrared spectroscopy characteristics of typical minerals and rocks in the Keketuohai has been established, and the thermal infrared spectroscopy characteristics of spodumene and lepidolite, ore - bearing pegmatites and surrounding rocks in rare metal deposits have been summarized in this study. Basic data support for the identification of rare metal minerals using thermal infrared spectroscopy and the exploration of granite pegmatite deposits has also been provided. [ABSTRACT FROM AUTHOR]

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This study focuses on the selection of a method combining simulations of mineralizing processes with three-dimensional (3D) mapping to quantitatively predict locations of concealed mineralization and to reduce uncertainty and multiplicity. The simulation of ore-forming processes for concealed mineralization requires the assessment of a region's structural geology, ages of lithological units, degree of metamorphism, and role of magmatism in the genesis of mineralization. The evolution of various factors affecting the development of geological processes in space and time is discussed, including the assessment of models combining regional deformation-magmatic activity-mineralized hydrothermal fluid based on empirical knowledge. Given that metallogeny is a study of the genesis and regional distribution of mineral deposits and emphasizes their spatial and temporal relationships, this paper uses empirical knowledge to predict the locations of concealed mineral deposits. Furthermore, the analysis of 3D geological modeling of concealed orebodies is a process that contributes to understanding the metallogenesis of mineral deposits. In this study of the Kaerqueka skarn and porphyritic deposits, geological, geographic, remote sensing and geochemical data collected from this region are processed using computer modeling techniques available in the Surpac software to establish a digital representation of the mineral field. The "block mapping modeling" theory, geostatistical methods, simulations of ore-forming processes, and 3D mapping methods are then combined to predict the locations of the most promising areas for concealed mineral deposits around the Kaerqueka deposit. This research introduces a new method for predicting and evaluating the locations of concealed orebodies by reducing multiplicity and uncertainty. [ABSTRACT FROM AUTHOR]

Abstract The timing and structure of Termination II (T-II) is still debatable as the number of high-quality records is insufficient. This study presents precisely dated stalagmite δ 18 O data between 133.4 ± 0.3 to 126.6 ± 0.3 ka BP (covering most of T-II) from north China, near the northern limit of the East Asian summer monsoon (EASM), an area sensitive to climate change. The onset of the last interglacial is constrained at 129.4 ± 0.3 ka BP, consistent with south Chinese speleothem records, further supporting the idea that Northern Hemisphere summer insolation plays an important role in initiating glacial terminations. An extended interval of heavy δ 18 O is observed immediately prior to this abrupt transition, named as the "Weak Monsoon Interval" (WMI) in south Chinese cave records, which was associated with the Heinrich Stadial 11 (H11) in the North Atlantic. A significant millennial-scale interstadial peaking at 132.7 ± 0.3 ka BP is identified preceding the weakest phase of the WMI. A synchronous counterpart is also found in some south Chinese speleothem and North Atlantic alkenone Mg/Ca SST records. It is inferred that the main H11 freshwater penetration possibly occurred after 131.5 ka BP, leaving some aspects of ocean and atmospheric circulation still in interstadial mode from 134 to 131.5 ka BP. Following the onset of the last interglacial, there was a millennial-scale "pause" in our δ 18 O record, synchronized with a "slowdown" in the rate of decrease in δ 18 O in south Chinese cave records. This is possibly a large regional climate oscillation, as it is also identified in some North Atlantic records, but one which is too weak to be a Younger Dryas (YD)-type event. In summary, compared to south Chinese cave records, significant millennial-scale climate oscillations before and after the synchronous onset of the last interglacial is the main feature of our record. Nevertheless, the sequence of these climate events remains very different from Termination I (T-I), which is possibly ascribed to the stronger insolation, higher atmosphere CO 2 , and the resultant faster and greater meltwater pulse to the North Atlantic during T-II than during T-I. Highlights • Termination II (T-II) in north China recorded by a precisely dated stalagmite. • The last interglacial onset was at around 129 ka BP in both north and south China. • Millennial-scale event of T-II in north China is more significant than south China. • Evolution of T-II is different from Termination-I shown by Chinese cave records. [ABSTRACT FROM AUTHOR]

Abstract An important exploration breakthrough has been achieved in the western subsag of the Bozhong subbasin, but the hydrocarbon accumulation mechanism was not clear. The hydrocarbon migration and accumulation mechanism of the western subsag of the Bozhong subbasin is discussed based on the modeling of hydrocarbon migration pathways and the study of late-stage reactivation of neotectonic faults. Three processes for lateral petroleum migration and accumulation can be recognized in the studied area: 1) migration and accumulation along the T8 unconformity; 2) migration and accumulation within the Guantao Formaiton (N 1 g); and 3) interaction of migration and accumulation along the T8 unconformity and Guantao Formation (N 1 g). The reactivation of faults in the studied area began 5.1 Ma. Following hydrocarbon lateral migration, late-stage reactivated neotectonic faults serve as effective vertical conduits for hydrocarbon migration and accumulation into the shallow Minghuazhen Formation (N 1 m) reservoirs. The modeling results of preferential petroleum migration pathways (PPMPs) and favorable accumulation areas are consistent with the actual exploration results. Two kinds of potential exploration targets can be predicted in the northwestern Bozhong subbasin: the first kind is hydrocarbon accumulation areas near or within generative kitchens (e.g. Target 1); the other kind is hydrocarbon accumulation areas removed from the generative kitchens, but with hydrocarbon sourcing from multiple generative kitchen and numerous PPMPs (e.g. Target 2). Studying preferential petroleum migration pathways will help reduce exploration risk. Highlights • The T8 unconformity and Guantao Formation (N 1 g) carrier beds are favorable hydrocarbon lateral migration conduits. • Late-stage reactivated faults during neotectonism serve as favorable conduits for vertical hydrocarbon migration. • Proven oil fields usually have multiple generative kitchens and numerous preferential petroleum migration pathways. • Potential exploration targets can be predicted based on preferential petroleum migration pathways. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • The ∼2.0 Ga Kongling mafic dikes are the oldest mafic intrusions in South China. • These dikes were formed in a back-arc basin during the assembly of Columbia supercontinent. • The linkage between South China and Northwest Laurentia, Northwest Australia and Siberia needs to be re-examined. Abstract Paleoproterozoic mafic dikes from the Kongling Complex in South China provide an ideal opportunity to examine mantle properties and tectonic evolution of the Yangtze Block and thus to understand the paleo-position of South China in the Columbia supercontinent. The 2.0 Ga dikes are the oldest mafic intrusions identified in the Yangtze Block by far. Samples from the dikes consist of fine to medium-grained dolerite and have variable SiO 2 (43.48–52.61 wt%) and MgO contents (3.17–7.35 wt%). They are enriched in LREE and show slightly negative to positive Eu anomalies (Eu/Eu∗ = 0.85–1.06). Their primitive mantle-normalized trace element patterns are characterized by enrichment of large-ion lithophile elements (Rb, Ba, Pb) and depletion of high-field-strength elements (U, Nb, Ta, Ti). Rocks from the dikes have variable initial 87Sr/86Sr ratios (0.698874–0.710753), εNd values (−3.0 to +4.1) and zircon εHf values (−2.7 to +3.4). These geochemical features indicate that their parental magmas were formed by <10% partial melting of a spinel-bearing lherzolite mantle in a back-arc basin setting. Paleoproterozoic mafic rocks from South China, Northwest Laurentia, Northwest Australia and Siberia had different trace element ratios and crystallization ages, their mantles had different thermal states. Thus, we argue against the previous model that the four continents were assembled together in the Columbia supercontinent. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • 498–505 Ma ophiolites occurred in the East Kunlun orogen. • Mafic rocks are derived from melting of a mantle wedge. • The ophiolite represents a relict of nascent back-arc basin. Abstract Early Palaeozoic ophiolites emplaced in the central East Kunlun fault zone (CEKF) offer critical clues to the tectonic evolution of the Proto-Tethys ocean and the accretionary process of CEKF. The Qushi'ang Ophiolite, located within the eastern segment of the CEKF, consists of dismembered serpentinites, meta-gabbros and meta-basalts. This study presents petrologic, whole-rock geochemical, and in situ zircon U-Pb and Hf isotope data for basic rocks (both metagabbros and metabasalts) from the Qushi'ang ophiolite to constrain the formation age and tectonic setting of the ophiolite. Zircons from two meta-gabbro samples yield concordant U-Pb ages of ca. 498 Ma and ca. 505 Ma, indicating that the Qushi'ang ophiolite was formed in the late Cambrian. The meta-gabbros and meta-basalts show significant enrichment in large ionic lithophile elements (LILEs), such as Cs, Rb, Ba, U, and Pb, and depletion in high field strength elements (HFSEs), such as Nb, Ta, Zr, and Ti, suggesting the influence of fluids derived from a subducting oceanic slab. On the N-MORB normalized trace element diagrams, these rocks share similar features with arc basalts and back-arc basalts and far away from fore-arc basalts (FABs) and normal mid-ocean basalts (N-MORBs). Low zircon ε Hf (t) values (−2.9 to +0.2) for the meta-gabbros further indicate that the Qushi'ang ophiolite likely originated from an weakly enriched mantle wedge source. Geochemical discrimination diagrams show that the Qushi'ang ophiolite formed in a back arc basin setting. Our new analyses, combined with previous data, suggest that the Qushi'ang ophiolite represents a relict of a nascent back-arc basin, similar to the scenario of the Okinawa trough in Western Pacific. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Triassic detritus in the northwestern Ordos were mostly sourced from the Alxa Massif. • Post-collision related basin formed in the northwestern Ordos at Middle-Late Triassic. • The Alxa Massif was the western extension of the North China Craton during Triassic. Abstract The Helanshan Tectonic Belt is situated among the Qilian Orogenic Belt to the southwest, the Alxa Massif to the west and the Ordos Block to the east. The Helanshan Tectonic Belt has received increasing attention since it was argued as the plate boundary separating the Alxa Massif from the Ordos Block, and hence Alxa Massif was isolated from the North China Craton during Triassic. The Middle to Upper Triassic strata in the northwestern Ordos and the Helanshan Tectonic Belt witnessed the tectonic evolutionary processes between the Alxa Massif and the Ordos Basin, hence are pivotal to understand the relationship between the Alxa Massif and the North China Craton. In this work, integrated paleocurrent orientation, gravel component, sandstone modal composition and detrital zircon U–Pb isotopic analyses were applied to trace the source area and reconstruct the source-to-sink relations between the Alxa Massif and Ordos Basin. The southeast orientated paleocurrent directions suggest detritus in the northwestern Ordos were mostly sourced from the northwest. Clastic compositions reveal a mixed orogeny provenance, including magmatic arc and continental block sources. Detrital zircons from four sandstones in the Helanshan Tectonic Belt yields four major LA-ICPMS U-Pb age groups of 2600–2200 Ma, 2000–1700 Ma, 480–400 Ma and 350–200 Ma, suggesting multiple-sourced provenance. Comparing to the magmatic records in the Alxa Massif and the Qilian Orogenic Belt, the Triassic detritus in the Helanshan Tectonic Belt were mainly from the Alxa Massif with additional supplements from the Qilian Orogenic Belt, which finally debouched to the lacustrine in the interior Ordos Basin to the southeast. Triassic basin evolution of the northwestern Ordos was further associated with post-collision in the Alxa Massif after the closure of the Paleo-Asian Ocean. [ABSTRACT FROM AUTHOR]

The Xiaojiashan tungsten deposit is located about 200 km northwest of Hami City, the Eastern Tianshan orogenic belt, Xinjiang, northwestern China, and is a quartz vein‐type tungsten deposit. Combined fluid inclusion microthermometry, host rock geochemistry, and H–O isotopic compositions are used to constrain the ore genesis and tectonic setting of the Xiaojiashan tungsten deposit. The orebodies occur in granite intrusions adjacent to the metamorphic crystal tuff, which consists of the second lithological section of the first Sub‐Formation of the Dananhu Formation (D2d12). Biotite granite is the most widely distributed intrusive bodies in the Xiaojiashan tungsten deposit. Altered diorite and metamorphic crystal tuff are the main surrounding rocks. The granite belongs to peraluminous A‐type granite with high potassic calc‐alkaline series, and all rocks show light Rare Earth Element (REE)‐enriched patterns. The trace element characters suggest that crystallization differentiation might even occur in the diagenetic process. The granite belongs to postcollisional extension granite, and the rocks formed in an extensional tectonic environment, which might result from magma activity in such an extensional tectonic environment. Tungsten‐bearing quartz veins are divided into gray quartz vein and white quartz veins. Based on petrography observation, fluid inclusions in both kinds of vein quartz are mainly aqueous inclusions. Microthermometry shows that gray quartz veins have 143–354°C of Th, and white quartz veins have 154–312°C of Th. The laser‐Raman test shows that CO2 is found in fluid inclusions of the tungsten‐bearing quartz veins. Quadrupole mass spectrometry reveals that fluid inclusions contain major vapor‐phase contents of CO2, H2O. Meanwhile, fluid inclusions contain major liquid‐phase contents of Cl−, Na+. It can be speculated that the ore‐forming fluid of the Xiaojiashan tungsten deposit is characterized by an H2O–CO2, low salinity, and H2O–CO2–NaCl system. The range of hydrogen and oxygen isotope compositions indicated that the ore‐forming fluids of the tungsten deposit were mainly magmatic water. The ore‐forming age of the Xiaojiashan deposit should to be ~227 Ma. During the ore‐forming process, the magmatic water had separated from magmatic intrusions, and the ore‐bearing complex was taken to a portion where tungsten‐bearing ores could be mineralized. The magmatic fluid was mixed by meteoric water in the late stage. The Xiaojiashan tungsten deposit is located about 200 km northwest of Hami City, Eastern Tianshan orogenic belt, Xinjiang, northwestern China and is a quartz vein‐type tungsten deposit. In this contribution, we report new results obtained from ore geology research, fluid inclusion and H–O stable studies for the Xiaojiashan deposit. [ABSTRACT FROM AUTHOR]

The Acite ophiolitic mélange represents a remnant of the Proto-Tethys forearc oceanic lithosphere. Two gabbros yield zircon 206Pb/238U ages of 510-512 Ma. The magmatic rocks are divided into three subtypes: (1) Mid-ocean ridge basalt (MORB) -like forearc basalts (FABs), (2) Low-titanium tholeiitic gabbros (LTGs), and (3) Normal calc-alkaline dacites (CADs). The FABs have comparatively higher TiO2 concentrations (1.13-1.42 wt%) and show almost flat REE patterns. In the NMORB normalized trace element patterns, the FABs display flat distributions of high field strength element (HFSE). The εNd(t) values of FABs range from +4.0 to +4.8. These features are similar to the composition of Izu-Bonin-Mariana forearc basalts (FABs). LTGs are characterized by higher contents of MgO (8.85-9.95 wt%) and lower concentration of TiO2(0.29-0.50 wt%). They show LREE-depleted patterns, however having comparatively lower total REE contents than those of FABs. The εNd(t) values of LTGs range from +7.4 to +8.4. These features show that LTG magmas originated from a progressively depleted mantle source. In contrast, the CADs having higher SiO2 contents (63.58-70.92 wt%) have higher total REE contents. In the NMORB normalized trace element patterns, CADs are characterized by enrichment of LILEs and depletion of HFSEs. CADs have negative εNd(t) values ranging from -9.8 to -10.5, which are likely suggestive of a crust-derived source. The rock association of FABs and LTGs, together with tectonic discrimination plots and regional data, suggest a forearc setting above the SSZ for Acite ophiolitic mélange. [ABSTRACT FROM AUTHOR]

The involvement of the North China Craton (NCC) in the assembly or breakup of Rodinia has long been debated. Studies of palaeomagnetism, mafic sills (dikes), igneous events, and sedimentary records have led to contrasting opinions on this topic. No igneous events related to the late Mesoproterozoic assembly of Rodinia have been reported in the NCC. However, the authors found numerous late Mesoproterozoic zircons in the Tonian system on the northern margin of the NCC. The Tonian Zhulazhagamaodao formation is composed of meta-sandstone, siltstone, slate, carbonate, and dolomine of the littoral to neritic facies and occurs mainly in the western part of the Bayan Obo-Zhaertai-Langshan rift. U-Pb dating of detrital zircons from the Tonian system reveals age peaks at 1079 ± 23 Ma, 1092 ± 22 Ma, 1175 ± 50 Ma, 1175 ± 18 Ma, 1260 ± 45 Ma, 1266 ± 16 Ma, and 1270 ± 26 Ma, which correspond to the timing of Rodinia assembly. Considering that coeval igneous rocks and orogenic belts developed mostly in the Laurentia-Baltica cratons, we propose that these cratons supplied clastic material to the northern margin of the NCC and that they had a close spatial relationship between each other during the Tonian. [ABSTRACT FROM AUTHOR]

Abstract: The South Tien Shan (STS) belt results from the last collision event in the western Central Asian Orogenic Belt (CAOB). Understanding its formation is of prime importance in the general framework of the CAOB. The Atbashi Range preserves high‐P (HP) rocks along the STS suture, but still, its global metamorphic evolution remains poorly constrained. Several HP units have been identified: (a) a HP tectonic mélange including boudins of mafic eclogites in a sedimentary matrix, (b) a large (>100 km long) high‐P metasedimentary unit (HPMU) and (c) a lower blueschist facies accretionary prism. Raman Spectroscopy on carbonaceous material combined with phengite and chlorite multiequilibria and isochemical phase diagram modelling indicates that the HPMU recorded homogeneous P–T conditions of 23–25 kbar and 560–570°C along the whole unit. 40Ar/39Ar dating on phengite from the HPMU ranges between 328 and 319 Ma at regional scale. These ages are interpreted as (re‐) crystallization ages of phengite during Tmax conditions at a pressure range of 20–25 kbar. Thermobarometry on samples from the HP tectonic mélange provides similar metamorphic peak conditions. Thermobarometry on the blueschist to lower greenschist facies accretionary prism indicates that it underwent P–T conditions of 5–6 kbar and 290–340°C, highlighting a 17–20 kbar pressure gap between the HPMU‐tectonic mélange units and the accretionary prism. Comparison with available geochronological data suggests a very short time span between the prograde path (340 Ma), HP metamorphic peak (330 Ma), the Tmax (328–319 Ma) and the final exhumation of the HPMU (303–295 Ma). Extrusion of the HPMU, accommodated by a basal thrust and an upper detachment, was driven by buoyant forces from 70–75 km up to 60 km depth, which directly followed continental subduction and detachment of the HPMU. At crustal depths, extrusion was controlled by collisional tectonics up to shallow levels. Lithological homogeneity of the HPMU and its continental‐derived character from the North Tien Shan suggest this unit corresponds to the hyper‐extended continental margin of the Kazakh continent, subducted southward below the north continental active margin of the Tarim craton. Integration of the available geological data allows us to propose a general geodynamic scenario for Tien Shan during the Carboniferous with a combination of (a) N‐dipping subduction below the Kazakh margin of Middle Tien Shan until 390–340 Ma and (b) S‐dipping subduction of remaining Turkestan marginal basins between 340 and 320 Ma. [ABSTRACT FROM AUTHOR]

Iron‐rich nodules occur on the Yangtze Platform, South China, especially along the marginal area, during the late Middle and early Late Ordovician (Darriwilian–Sandbian). Based on the study of samples from the Daling section, Anhui Province, these nodules include: (1) oncoids; (2) coated bioclasts; and (3) coated micritic intraclasts, all of which potentially have a similar biological origin. The nodule‐bearing strata were deposited in a midouter ramp setting, indicating sediment starvation and open marine conditions, possibly combined with anoxia in deeper basinal areas and cool water upwelling during the formation of the nodules, rather than terrestrial input or local tectonic movement. The widespread distribution of iron‐rich nodules at this time was probably favoured by high sea level and cooling climate, conditions that simultaneously favoured the evolutionary radiations of the GOBE in South China. Thus, these nodules form a time‐specific signature of a critical time in the evolution of the marine ecosystem in the context of local environmental background along the marginal Yangtze Platform. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Zhengguang is an intermediate sulfidation epithermal deposit formed in a continental arc. • Zhengguang is the oldest IS deposit in the world and the oldest epithermal deposit in CAOB. • Adakitic dacite porphyry formed from partial melting of the subducted oceanic plate. • Intermediate dikes contain low Mg-andesitic rocks and high Mg-andesitic rocks. • Neoproterozoic continental crust growth is present in the Duobaoshan area. Abstract The Zhengguang Au-Zn deposit is a large epithermal deposit adjacent to the Tongshan and the Duobaoshan porphyry Cu deposits in the Duobaoshan ore field, NE China. The host rocks mainly consist of andesite, andesitic tuff, and volcanic breccia. There are also many diorite dikes and subvolcanic rocks, including dacite porphyry and andesite porphyry. This contribution presents the zircon U-Pb ages, whole rock elemental and Sr-Nd isotopic compositions and zircon in situ Hf isotopic data for volcanic and subvolcanic rocks at Zhengguang. The dating results show that there are at least three episodes of magmatic events in the Zhengguang area: first, the extrusion of main host andesite of the Duobaoshan Formation (>490 Ma); second, the emplacement of copious andesitic dikes (490–470 Ma); and finally, early Silurian intermediate magmatic activity (440–436 Ma). The dacite porphyry emplaced at 480 Ma has relatively high SiO 2 (63.5–64.7 wt%) and Sr (250–324 ppm) content, low Yb (0.59–0.67 ppm) and Y (5.65–6.63 ppm) content, and low initial 87Sr/86Sr ratios (0.7026–0.7031), suggesting an adakitic affinity. Given the positive εNd(t) values (+6.1 to + 7.1), εHf(t) values (+7.5 to + 13.5), high Mg# values (61–62), slightly high content of Cr (87.7–92.6 ppm), and Ni (37.6–46.9 ppm), we propose that the porphyry was derived from partial melting of subducted slabs of the Paleo-Asian oceanic plate with input from the mantle wedge during the ascent. The intermediate rocks can be divided into low Mg-andesitic rocks (LMAR, Mg# 33–54, Cr 14–144 ppm, and Ni 4–39 ppm) that originated from partial melting of the juvenile lower crust underplated by the mantle wedge-derived magma and high Mg-andesitic rocks (HMAR, Mg# 58–76, Cr 217–774 ppm, and Ni 81–419 ppm) derived from the partial melting of the slab fluid-metasomatic mantle wedge. The statistics of T DM2 of zircon Hf suggest that certain amounts of Neoproterozoic (particularly 800–600 Ma) continental crust growth were involved in the eastern part of the Central Asian Orogenic Belt (CAOB), as evidenced in the Zhengguang area. Based on the geological relationship and mineralization style, we suggest that the Zhengguang deposit is an intermediate sulfidation epithermal deposit formed at ca. 480 Ma in a continental arc setting. Our work shows that Zhengguang is the oldest epithermal deposit in the CAOB and the oldest intermediate sulfidation (IS) epithermal deposit in the world. The identification of these characteristics is important for better understanding epithermal deposits in China and will add new insights about prospecting IS deposits in similar tectonic settings, especially in the CAOB. [ABSTRACT FROM AUTHOR]

Recent oil discoveries in the L13-L15 sub-sag area in the Pearl River Mouth basin have inspired interest in Paleogene hydrocarbon targets. However, the structures and their control on reservoirs have not been completely studied. The aim of this paper is to address the tectonics and Eocene sedimentation based on 3D seismic data. We documented characteristics from four aspects of the faults in the study area: (a) fault arrangement; (b) fault segmentation; (c) flower structures; and (d) distribution of the depocenters along the faults. Based on the above data, we propose that the structures in the studied area were formed by a right-handed wrench. The principal shear for this model was caused by NNE- to NE-ward motion of the eastern part of the Eurasia plate due to the collision of the Indian-Australian and Eurasian plates starting approximately 49 Ma ago. The L13-L15 sub-sag area underwent early Eocene rifting, a late Eocene rifting-depression transition and an Oligocene-Quaternary thermal depression. The rift phase included three stages: the initial rifting, intensive rifting and late rifting. The deep lake mudstone deposited during the intensive rifting stage is the source rock with the most potential for oil generation. Shallow lake source rocks formed in the late rifting and transition stages are the secondary source rocks. Reservoir sweet spots were formed in the early period of the intensive rifting and late rifting stages. The junction sites between the front of the meandering river delta plain and fault steps are favorable places for good reservoirs. The sediments in the transition stage are rich in sandstone, making them perfect sites for prospecting reservoirs. [ABSTRACT FROM AUTHOR]

Guizhou Karst Plateau is located at the center of the karst region in Asia, where landslides are a typical disaster. Affected by the local karst environment, the landslides in this region have their own characteristics. In this study, 3975 landslide records from inventories of the Guizhou karst plateau are studied. The geographical detector method is used to detect the dominant casual factor and predominant multi-factor combinations for the local landslides. The results show that landslides are prone to areas on slopes between 10° and 35°, of clay rock, in close proximity to gullies, and especially in areas of moderate vegetation, dryland, and mild rocky desertification. Continuous precipitation over 10 days has a great effect on landslide occurrence. Compared with the individual factors, the impact of two-factor interaction has greater explanatory power for landslide volume. The volume of earthquake-induced landslides is predominantly controlled by the interactions of faults and slopes, while that of human-induced landslides is affected by the interactions of land cover and hydrological conditions. For rainfall-induced landslides, the dominant interactions vary in different regions. In the central karst basin, the interactions between faults and precipitation can explain over 90% of the variations in landslide volumes. In the southern hilly karst region, the interactions between lithology and slope can explain over 71% of the variations in landslide volume and those between fault and land-use can explain 50% of the variations of the landslide volumes in the northeastern mountainous karst region. [ABSTRACT FROM AUTHOR]

The “Yanshanian movement” (tectonism) was first recognized in the Western Hills of Beijing and represents the most intense Mesozoic tectonic event in eastern China. Although many researches have been conducted since its identification in 1927, the timing for initiation of the Yanshanian tectonism has not been well constrained. The Jurassic sedimentary succession in the Western Hills of Beijing consists of two volcanic units and interbedded coal-bearing strata, which is similar to those in other regions of the Yanshan Fold-and-Thrust Belt (YFTB). As the earliest Mesozoic volcanism in the Western Hills of Beijing, the Nandaling Formation contains the earliest volcanic and sedimentary records that are associated with the initiation of the Yanshanian tectonism. Previous researches considered the Nandaling volcanic rocks as Early Jurassic in age based on the floral fossil assemblage of Coniopteris–Phoenicopsis in the Yaopo Formation that conformably overlies the Nandaling Formation. In this study we perform a systematic geological survey and present the results of zircon U–Pb dating of the Nandaling volcanic rocks to demonstrate that both the Nandaling volcanic rocks and the overlying floral fossil assemblage are Middle Jurassic in age. LA–ICP–MS zircon U–Pb dating of the Nandaling volcanic rocks in the northern part of the basin yields eruption ages of 175 ± 1 to 168 ± 2 Ma. Dioritic porphyry sills are intruded concordantly into folded Mesoproterozoic–lower Paleozoic strata of the Qingbaikou anticline, and yield a zircon U–Pb age of 177 ± 1 Ma. These ages indicate that the initiation of the Yanshanian basins, and therefore the initiation of the Yanshanian tectonism, occurred no earlier than the Middle Jurassic. Our 40 Ar– 39 Ar dating of the Nandaling volcanic rocks yields younger ages of 138–151 Ma that show a southward-younging trend, indicating that the Nandaling volcanic rocks in the Western Hills of Beijing were overprinted by a tectono-thermal event that peaked during the Early Cretaceous. [ABSTRACT FROM AUTHOR]

Abstract: This study identified soft–sediment deformation structures (SSDS) of seismic origin from lacustrine sediments in the late Quaternary paleo–dammed lake at Tashkorgan, northeastern Pamir. The observed deformation structures include sand dykes, liquefied diapir and convolute structures, gravity induced SSDS, and thixotropic pillar and tabular structures. We conducted a preliminary study on the morphology, formation and trigger mechanisms of pillar and tabular structures formed by liquefaction of underlying coarse sand and thixotropy of the upper silty clay. The regional tectonic setting and distribution of lacustrine strata indicate that the most probable trigger for the SSDS in lacustrine sediments was seismic activity, with an approximate earthquake magnitude of M>6.0; the potential seismogenic fault is the southern part of the Kongur normal fault extensional system. AMS 14C dating results indicate that the SSDS were formed by seismic events occurring between 26050±100 yrBP and 22710±80 yrBP, implying intense fault activity in this region during the late Pleistocene. This study provides new evidence for understanding tectonic activity and regional geodynamics in western China. [ABSTRACT FROM AUTHOR]

We observed abnormal changes of the water temperature in Yushu (YSWT) well, China, most of which were followed by earthquakes. This study statistically analyzes the correlation between the magnitude and duration of the anomalies in YSWT and earthquakes in the Tibetan block and its margins. The effectiveness of using observed YSWT data to predict earthquakes was quantitatively examined by the Molchan error diagram method. The results show that (1) the YSWT underwent several abnormal changes marked by “V”-shaped patterns, which might be related to several earthquakes that occurred in the Tibetan block and its margins. The extent and duration of the abnormal changes in the YSWT were linearly related to the magnitude of the earthquake; i.e., the higher the magnitude, the greater the change in the YSWT, and the shorter the duration. (2) Abnormal changes in the YSWT are somewhat predictive of earthquakes with magnitudes ≥5.5 (≥M5.5) within 800 km of the Yushu well and ≥M6.5 earthquakes in the Tibetan block and its margins. The prediction has a probability gain of approximately 2, and the most likely time period for an earthquake to occur is within approximately 3 months after the occurrence of an YSWT anomaly. Most of the anomalies in YSWT appeared before earthquakes in the thrust of block margins. Notably the larger strains from the earthquake did not produce any response. We speculate that the preseismic responses reflect the regional tectonics, such as the motion of the Indian plate, straining sub-blocks of the Tibetan block. [ABSTRACT FROM AUTHOR]

The timing of the “Yanshanian Movement” and the tectonic setting that controlled the Yanshan fold-and-thrust belt during Jurassic time in China are still matters of controversy. Sediments that filled the intramontane basins in the Yanshan belt perfectly record the history of “Yanshanian Movement” and the tectonic background of these basins. Recognizing syn-tectonic sedimentation, clarifying its relationship with structures, and accurately defining strata ages to build up a correct chronostratigraphic framework are the key points to further reveal the timing and kinematics of tectonic deformation in the Yanshan belt from the Jurassic to the Early Cretaceous. This paper applies both tectonic and sedimentary methods on the fold-and-thrust belt and intramontane basins in the Zhangjiakou area, which is located at the intersection between the western Yanshan and northern Taihangshan. Our work suggests that the pre-defined “Jurassic strata” should be re-dated and sub-divided into three strata units: a Late Triassic to Early Jurassic unit, a Middle Jurassic unit, and a Late Jurassic to early Early Cretaceous unit. Under the control of growth fold-and-thrust structures, five types of growth strata developed in different growth structures: fold-belt foredeep type, thrust-belt foredeep type, fault-propagation fold-thrust structure type, fault-bend fold-thrust structure type, and fault-bend fold-thrust plus fault-propagation fold composite type. The reconstructed “source-to-sink” systems of Late Triassic to Early Jurassic, Middle Jurassic and Late Jurassic to early Early Cretaceous times, which are composed of a fold-and-thrust belt and flexure basins, imply that the “Yanshanian Movement” in our study area started in theMiddle Jurassic. During Middle Jurassic to early Early Cretaceous times, there have been at least three stages of fold-thrust events that developed “Laramide-type” basement-involved fold-thrust structures and small-scale intramontane broken “axial basins”. The westward migration of a “pair” of basement-involved fold-thrust belt and flexure basins might have been controlled by flat subduction of the western Paleo-Pacific slab from the Jurassic to the Early Cretaceous. [ABSTRACT FROM AUTHOR]

Mountain highways in China are located in various natural geographical areas with intense tectonic activity, steep topography and a high frequency of extreme precipitation events. These conditions make the highways vulnerable to the occurrence of multiple large debris flows simultaneously during heavy rainfall. To manage this hazard risk, a broader understanding of the hazard effects of debris flows and the vulnerability of highways is needed to reduce the losses resulting from these hazardous events. Accordingly, we analysed the effects of debris flow hazards on mountain highways and established an updated systematic indicator system to describe the vulnerability of highway infrastructure and movable hazard-affected objects. Next, we proposed a new integrated model of highway vulnerability based on the environmental sensibility, structural properties and functional effects of the highway infrastructure and on the exposure probability and quantity of movable hazard-affected objects. By analysing the characteristics of elements affected by debris flows, we developed a systematic and quantitative method of vulnerability assessment for mountain highways. Finally, this implemented method was applied to a case study in the Xiqu section of the Sichuan-Tibet Highway, an area seriously affected by debris flows during each rainy season. The hazard characteristics of disasters were analysed, and the affected highway sections were divided into four vulnerability levels. The analysis of the results indicated that the calculated vulnerability coincides with the actual effects of the disaster, which strongly suggests that the vulnerability assessment generated by the proposed method can serve as a pertinent guide for route selection, road rehabilitation and hazard mitigation of highways affected by debris flows in mountainous regions. [ABSTRACT FROM AUTHOR]

The tectonic evolution of the Pamir bears essential information for understanding intracontinental tectonic processes within the context of India-Asia convergence. However, it is unclear whether the arcuate shape of the Pamir is entirely the result of the India-Asia collision, or may have been in part an inherited, pre-Cenozoic feature. In this study, we address the evolution of the NE Chinese Pamir during the Paleogene by reviewing the stratigraphy of twelve sections in the western Tarim Basin and the establishment of sedimentary facies. The results indicate three episodes of deposition of alluvial coarse sediments in the foreland regions of NE Chinese Pamir during the (1) early Paleocene, (2) late Paleocene to early Eocene and (3) middle Eocene to Oligocene, respectively. These are correspondingly attributed to (1) retroarc deformation in an Andean-type margin of the southern Asia during subduction of the Neo-Tethys Ocean, (2) the immediate response in the Pamir to the India-Asia collision, and (3) continued India-Asia convergence. The alluvial conglomerates with grain-size up to 5–10 cm, imply a transport distance <60 km from the fan apex. This result, together with the 20–50 km northward thrust displacements, suggests that the orogen/basin boundary between the Pamir and the Tarim-Alai Basin was located less than ca. 80–110 km to the south from the present location of the Main Pamir Thrust during the Paleogene, indicating the arcuate shape of the Pamir was already largely established by the Paleogene, rather than entirely a result of the India-Asia continental collision. [ABSTRACT FROM AUTHOR]

The Longyao ground fissure (LGF) is the longest and most active among more than 1000 ground fissures on the North China Plain. There have been many studies on the formation mechanism of the LGF, due to its scientific importance and its potential for damage to the environment. These studies have been based on both regional tectonic analysis and numerical simulations. In order to provide a better understanding of the formation mechanism, the deformation of the crack and its surrounding environment should be taken into consideration. In this paper, PS-InSAR technology was employed to assess the ground deformation of LGF and its surrounding area, using L-band ALOS-1 PALSAR images from 2007 to 2011. The characteristics of ground deformation, relationships between fissure activity and surrounding faults and groundwater exploitation were analyzed. This study shows that the north side of Longyao fault (LF) is uplifting while the south side is subsiding. This provides the tectonic conditions responsible for the activity of the ground fissure. Local groundwater exploitation also plays an important role in the development of ground fissures. InSAR observations were modeled to infer the loading depth (-2.8 km) and the slip rate (31.1 mm/yr) of LF. [ABSTRACT FROM AUTHOR]

From the east of the Xuefengshan tectonic zone (XTZ) to the Pacific coast of the South China Block, there exist widespread Mesozoic magmatic rocks, which attract a great deal of attention for their forming mechanism and evolutional history. Among them, the Mesozoic Jishou diabase located at the west of the XTZ is reported in this study. Based on our geochronologic analysis, the diabase has a U–Pb age of 134 ± 2.3 Ma. The diabase belongs to calc‐alkaline series in a SiO2‐K2O diagram and illustrates significant enrichment in light rare earth elements and flat heavy rare earth elements without obvious Eu anomalies. Meanwhile, the diabase has negative εHf(t) and εNd(t) values and higher radiogenic 87Sr/86Sr(t) ratios, suggestive of EM2‐like Sr‐Nd isotopic compositions. The diabase shows high variations in 207Pb/204Pb(t; 15.609–15.671), 206Pb/204Pb(t; 17.943–18.742), and 208Pb/204Pb(t; 38.268–39.302). It is suggested that the Jishou diabase may be generated from the lithospheric mantle in response to the decompression melting accompanied by lithospheric extension during Pacific subduction process. During the Early Cretaceous (145–120 Ma), the upwelling and melting of the mantle occurred under the XTZ, causing intraplate Jishou diabase magma. Subsequently, the significantly descending of the subducted Paleo‐Pacific slab led progressively eastward generation and migration of subduction‐related magmas, resulting in a widespread distribution of igneous rocks in the Cathaysia Block. [ABSTRACT FROM AUTHOR]

The Jingdezhen ductile shear zone is evolved from the Neoproterozoic Zhangyuan ophiolite mélange belt in the eastern Jiangnan Orogen, South China. Comprehensive study of geometry, kinematics, quartz c-axis fabric, temperature-pressure conditions and geochronology were conducted in this study. The Jingdezhen shear zone extends ∼180 km along the NE orientation with two groups of subvertical foliation and subhorizontal lineation. One group of foliation strikes NEN orientation whereas another one NEE orientation. Field investigation, microscopic observation and quartz c-axis fabric show that sinistral shearing along NEN-striking foliation occurred earlier than dextral shearing along NEE-striking foliation. Syn-tectonic staurolite porphyroblasts and deformation manner of feldspar imply that sinistral shearing occurred at 530-420 ºC and 6-2 kbar. Deformation manner and c-axis fabric of quartz and pre-tectonic staurolite porphyroblasts indicate that dextral shearing took place at 420-300 ºC. LA-ICP-MS zircon U-Pb and mica 40Ar/39Ar dating indicate that the sinistral shearing occurred during Neoproterozoic orogeny (830-800 Ma) whereas the dextral shearing at 447±12 Ma. The sinistral shearing resulted from the Neoproterozoic final assembly between the Yangtze and Cathaysia blocks. The dextral shearing was caused by Early Paleozoic orogen parallel extension and clockwise rotation. [ABSTRACT FROM AUTHOR]

Xi’an ground fractures are the most typical ground fractures in China. Fourteen fractures have nearly divided the historical city into several distinct sections. These fractures are parallel and distributed in NEE direction at the same interval, with all features exhibiting a down dropping southerly block which extends to connect with the underlying fault. The activities of fractures are primarily expressed as normal faults. The faulted strata are well defined and dislocation displacement increases with depth. Thus, fractures have the characteristics of syn-sedimentary faults, which constitute the hanging wall of the Lintong-Chang’an fault branch system. Crustal thinning caused by the uplifting of upper mantle provides a power source for extension and stretching along the fracture surface of the upper crust, which results in a series of extensional faults and the suitable conditions for forming massive ground fractures. The movement of tectonic blocks influences the normal dip-slipping tension of Lintong-Chang’an fault branches, and produces a series of secondary tectonic fractures adjacent to surface, which constitute the prototype of ground fractures. The recent regional tensile stress produced by modern mainland deformation, also profoundly influences the current activity of Xi’an ground fractures. [ABSTRACT FROM AUTHOR]

A combined study of magnetic fabrics, zircon U-Pb geochronology and structural deformation was carried out for Late Paleozoic sedimentary and Mesozoic magmatic rocks in the southwestern Fujian rift basin, South China, aiming at deciphering the tectonic evolution during Late Mesozoic. Field observations showed that the Late Mesozoic structure deformations in southwestern Fujian were categorized into four phases: NW-SE compression, ENE-WSW extension, NNE-SSW compression and NNW-SSE extension, sequentially. Zircons picked out from Juzhou granite and WNW-trending diabase dykes showed complete crystal shapes and clear oscillatory zonings on their edges, and the U-Pb dating yielded ages of 132 and 141 Ma, respectively. The susceptibility ellipsoid magnitude parameters of the Juzhou granite are characterized by flaser type strain ellipsoid, with pole density center of K3 falling into the first and the third quadrants, these features revealed that the Juzhou granite formed in ENE-WSW compressional stress field, indicating the early stage of Early Cretaceous extrusion in southwestern Fujian. The late stage of Early Cretaceous NNE-SSW extension was limited by the widespread WNW-trending diabase dykes, which were usually regarded as important indications for a regional extensional setting. On the basic of the previous researches, structural deformation studies, and the deductions above, it can be concluded that southwestern Fujian experienced five main tectonic stages during Late Mesozoic: Early Jurassic extension, Middle-Late Jurassic thrusting, early stage of Early Cretaceous extension, late stage of Early Cretaceous compression and Late Cretaceous extension. [ABSTRACT FROM AUTHOR]

The Xujiaweizi (XJWZ) fault depression is a primary area for deep-seated gas exploration in Daqing. Through seismic profile interpretation, the main sag-controlling fault and structural characteristics in the XJWZ fault depression were analyzed based on folds and faults analysis. A three-dimensional geological model of the XJWZ fault depression was also set up to enable further discussion by means of structural physical modeling. According to our research, the basic structural framework of the XJWZ fault depression was the result of regional extension. Its formation and evolution were mainly controlled by the Xuxi fault. The structural framework of S-N blocking was due to changes in the fracture attitude. The Xuzhong uplift and the depressions on both sides belong to a normal-fault-related fold and were formed by controlling of the ramp/flat normal fault in the same tectonic movement period. [ABSTRACT FROM AUTHOR]

Abstract: In this study, plagiogranites in the Diyanmiao ophiolite of the southeastern Central Asian Orogenic Belt (Altaids) were investigated for the first time. The plagiogranites are composed predominantly of albite and quartz, and occur as irregular intrusive veins in pillow basalts. The plagiogranites have high SiO2 (74.37–76.68wt%) and low Al2O3 (11.99–13.30wt%), and intensively high Na2O (4.52–5.49wt%) and low K2O (0.03–0.40wt%) resulting in high Na2O/K2O ratios (11.3–183). These rocks are classified as part of the low‐K tholeiitic series. The plagiogranites have low total rare earth element contents (ΣREE)(23.62–39.77ppm), small negative Eu anomalies (δEu=0.44–0.62), and flat to slightly LREE‐depleted chondrite‐normalized REE patterns ((La/Yb)N=0.68–0.76), similar to N‐MORB. The plagiogranites are also characterized by Th, U, Zr, and Hf enrichment, and Nb, P, and Ti depletion, have overall flat primitivemantle‐normalized trace element patterns. Field and petrological observations and geochemical data suggest that the plagiogranites in the Diyanmiao ophiolite are similar to fractionation‐type plagiogranites. Furthermore, the REE patterns of the plagiogranites are similar to those of the gabbros and pillow basalts in the ophiolite. In plots of SREE–SiO2, La–SiO2, and Yb–SiO2, the plagiogranites, pillow basalts, and gabbros show trends typical of crystal fractionation. As such, the plagiogranites are oceanic in origin, formed by crystal fractionation from basaltic magmas derived from depleted mantle, and are part of the Diyanmiao ophiolite. LA–ICP–MS U–Pb dating of zircons from the plagiogranites yielded ages of 328.6±2.1 and 327.1±2.1Ma, indicating an early Carboniferous age for the Diyanmiao ophiolite. These results provide petrological and geochronological evidence for the identification of the Erenhot–Hegenshan oceanic basin and Hegenshan suture of the Paleo‐Asian Ocean. [ABSTRACT FROM AUTHOR]

Based on the seismic profiles, drilling, tomographic images and other geological data, we use the I2VIS code to program the Mesozoic finite‐difference numerical model in the southern part of the East China Sea Continental Shelf Basin (ECSCSB). We try to model the basin evolutionary process by setting up different boundaries to the 2‐D models. After analysing the simulation results of low‐speed and high‐speed stretching models, we found that under the condition of preliminary tensile value, the magma could not be generated in both rapid and slow stretching cases. This means that the regional extension of the Mesozoic ECSCSB is not the only dominant factor for basin evolution. Based on the analysis of the regional geological features and the modelling results, we suggest that the low‐velocity lithosphere mantle in the study area may be due to the melting of the mantle caused by the subduction and dehydration of the Izawa Nasaki Plate. The evolutionary process of the Mesozoic basins in the ECSCSB is closely related to regional extension and the magma upwelling caused by subduction and dehydration of the Izawa Nasaki Plate during the Mesozoic Era. The magma upwelling led to large‐scale magmatic events. It is likely to act in the Minjiang Sag, which resulted in the further rise of the Minjiang Sag and the formation of the present slope zone. [ABSTRACT FROM AUTHOR]

The Lower Silurian Longmaxi shale is the most important marine shale gas play in South China. Several hundred wells have been drilled to date, of which more than 150 wells have obtained high initial production (IP). Outside of the Sichuan Basin, however, wells drilled in the Lower Silurian Longmaxi shale do not reach flow rates that are commercial. Developing an understanding of the key factors controlling the IPs of Longmaxi shale is important in screening shale-resource plays. In this study, the TOC, thermal maturity, porosity, and gas saturation data obtained from Longmaxi shale of southeastern Chongqing area outside Sichuan Basin have been compared with that of Sichuan Basin. The results of this study show that the shales encountered display similar properties including TOC (>2%), thermal maturity (2.5–3.5% EqRo), and total porosity (3–6%). A good correlation between IPs and pressure coefficient suggest that the free gas content of gas shale controls on IPs. Porosity and gas saturation of gas shale are the main factors to control its free gas volume. The gas saturations in Longmaxi shale from high initial production wells in Sichuan Basin mainly range between 50 and 90%, however, that of shale in the southeastern Chongqing area are decreased to 10–30%. This is the directly reason for low IPs of wells. The contrasting gas saturation of Longmaxi shale between Sichuan Basin and the adjacent fold-thrust belts are interpreted to reflect, in part, differences in sealed condition of fluid system. Intensive tectonic movements caused the exhumation, faulting and fracturing, that reduced or destroyed the sealed ability of shale fluid system, which are the major factors for enhancing water saturation, decreasing fluid pressure and IPs. Finally, the study proposes several most favorable zones for Longmaxi shale gas exploration and development. [ABSTRACT FROM AUTHOR]

On 8 August 2017, a Ms7.0 earthquake stroke the city of Jiuzhaigou, Sichuan, China. The Jiuzhaigou earthquake occurred on a buried fault in the vicinity of three well-known active faults and this event offers a unique opportunity to study tectonic structures in the epicentral region and stress transferring. Here we present coseismic displacement field maps for this earthquake using descending and ascending Sentinel-1A Interferometric Synthetic Aperture Radar (InSAR) data. Deformation covered an area of approximately 50 × 50 km, with a maximum line-of-sight (LOS) displacement of ~22 cm in ascending and ~14 cm in descending observations on the west side of the source fault. Based on InSAR and Global Positioning System (GPS) measurements, both separately and jointly, we constructed a one-segment model to invert the coseismic slip distribution and dip angle of this event. Our final fault slip model suggests that slip was concentrated at an upper depth of 15 km; there was a maximum slip of ~1.3 m and the rupture was dominated by a left-lateral strike-slip motion. The inverted geodetic moment was approximately 6.75 × 10 18  Nm, corresponding to a moment magnitude of Mw6.5, consistent with seismological results. The calculated static Coulomb stress changes indicate that most aftershocks occurred in stress increasing zones caused by the mainshock rupture; the Jiuzhaigou earthquake has brought the western part of the Tazang fault 0.1–0.4 MPa closer to failure, indicating an increasing seismic hazard in this region. The Coulomb stress changes caused by the 2008 Mw7.8 Wenchuan earthquake suggest that stress loading from this event acted as a trigger for the Jiuzhaigou earthquake. [ABSTRACT FROM AUTHOR]

Abstract: The Xichang Basin in southeastern Tibet provides crucial information about formation and tectonic processes affecting the eastern Tibetan Plateau. To determine when and how the uplift developed, we conducted detailed studies of structures and obtained thermochronology data from the Xichang Basin and its periphery. The Xichang Basin is characterized by gentle deformation of the strata, segmented by an E‐vergent boundary thrust fault. Two stages of deformation, strike‐slip followed by an E‐W oriented shortening resulted in oblique shortening between the southeastern Tibetan Plateau and the Sichuan Basin. New apatite fission‐track data interpreted together with (U‐Th)/He data confirm a simple burial/heating and exhumation/cooling history across the Xichang Basin and its periphery. Subsidence and burial of the Xichang Basin peaked between 80–30 Ma, followed by mountain building with a protracted cooling starting at around 40–20 Ma, with rates of ca. 2.0–8.0 °C Myr−1 (i.e. 0.1–0.3 mm year−1). Our data indicate that the Xichang Basin has experienced ca. 2.5–5 km of exhumation, much more intensive than the ca. 1–2 km of exhumation inferred for the southwestern Sichuan Basin. Restored balanced cross‐sections of post‐Late‐Triassic strata along a ca. 250 km traverse indicate ca. 10–20% east‐west shortening strain (i.e. ca. 20–30 km) at the southeastern Tibetan Plateau during Cenozoic time. Study of crustal thickening and erosion supports a tectonic shortening mechanism to account for the uplift of the Xichang Basin on the southeastern Tibetan Plateau. [ABSTRACT FROM AUTHOR]

Turbidites of the Early Cretaceous Lingshandao Formation on Lingshan Island, eastern China, show numerous soft-sediment deformation structures. The turbidites accumulated in a rift basin plain on the distal part of a low-energy fan, together with autochthonous fine-grained sediments that settled from suspension. Occasionally, sets of both types of sediments slumped down the basin slope. The turbidites were studied in two sections. Paleocurrent directions, measured from sole marks at the base of the sandy turbidites, indicate a slope from SE to NW; this is consistent with the dip direction of the axial planes of the major slump folds. Among the numerous types of soft-sediment deformation structures that are present, two types are of special interest because of their specific genesis, viz. rip-up clasts and dome structures. It appears that rapid sedimentation must be considered as the main trigger behind these deformations: the rapid accumulation of particularly the sandy turbidites resulted in overloading of the underlying beds and then consequently in an increase in their pore-water pressure that induced liquefaction and fluidization, which triggered the formation of the rip-up clasts and dome structures. The downslope movement of freshly deposited turbidites after slope failure over the inclined sedimentary surface induced shear stresses, which resulted in the complication of the rip-up clasts and the preferred orientation of some dome structures. Both the dip directions of the axial planes of some of the dome structures and microfolds within the rip-up clasts are consistent with the paleocurrent direction indicated by the sole marks and the slump folds. [ABSTRACT FROM AUTHOR]

Two rock topples with the opposite dip direction, observed in the Ribangliangzi hill and facing the China Provincial Highway S211, are located on the upper stream of the planned dam of Jinchuan Hydropower Station in China. The new site for submerged part of Highway due to reservoir impoundment is designed to be a tunnel crossing the Ribangliangzi hill. However, at this hill, the stratum facing the Dadu River dips southwestward, whereas the stratum facing the Xinzha Gully dips northeastward. Therefore, it's regarded as an important slope structure that may lead to an occurrence of landslide directly threatening the future tunnel excavation stability and slope stability along the highway. This paper reports for the geologic structures of the overturned strata, formative processes and mechanism for toppling on cataclinal slopes. It was concluded that the toppling on cataclinal slopes was caused by a combination of toppling and sliding. Furthermore, to analyse the conditions for toppling on cataclinal slope, the cantilever beam model was established and analyzed the minimum strata dip angle required for toppling more prone to occur on cataclinal slope and the critical length of rock stratum. The results reveal that the toppling will be more prone to occur on cataclinal slope while the strata dip angle is greater than 60°even if under a very small external force or without the assistance of external forces. [ABSTRACT FROM AUTHOR]