Evolution of 3D tectonic stress field and fault movement in North China

IntroductionThe research on stress field interior the Earth is an either relative old or young branch of geoscience. Early in the 20th century, in order to learn the state of inner stress field, a few scholars had used simple ideal model to analyze big scale tectonic conformations and activities according to tide, gravity, rotation and inner thermal materials. So far, lots of problems on the state of the Earth stress field have not been solved completely yet. The origin of stress field, the d…     

Faulting on the Anninghe fault zone, Southwest China in Late Quaternary and its movement model

The Anninghe fault is one of the significant earthquake-generating fault zones in the Southwest China. Local his-torical record shows that a M≥7 strong earthquake occurred in the year of 1536. On the basis of the detailed air-photographic interpretation and field investigation, we have acquired the following knowledge: 1 The average sinistral strike-slip rate since the Late Pleistocene is about 3~7 mm/a; 2 There is important reverse faulting along the fault zone besides the main left-lateral strike-slip motion, and the shortening rate across the Anninghe fault zone due to the reverse faulting is about 1.7~4.0 mm/a. If the Xianshuihe fault zone is simply partitioned into the Anninghe and Daliangshan faults, we can also get a slip rate of 3~7 mm/a along the Daliangshan fault zone, which is the same as that on the Anninghe fault zone. Moreover, on the basis of our field investigation and the latest knowledge concerning the active tectonics of Tibetan crust, we create a dynamic model for the Anninghe fault zone.     

The abnormal mantle and deep tectonic process in the southern region of North China Plain

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Impacts of climate change on the Qingjiang Watershed’s runoff change trend in China

Qingjiang River, the second largest tributary of the Yangtze River in Hubei Province, has taken on the important tasks for power generation and flood control in Hubei Province. The Qingjiang River watershed has a subtropical monsoon climate and, as a result, has dramatic diversity in its water resources. Recently, global warming and climate change have seriously affected the Qingjiang watershed’s integrated water resources management. In this article, general circulation model (GCM) and watershed hydrological models were applied to analyze the impacts of climate change on future runoff of Qingjiang Watershed. To couple the scale difference between GCM and watershed hydrological models, a statistical downscaling method based on the smooth support vector machine was used to downscale the GCM’s large-scale output. With the downscaled precipitation and evaporation, the Xin-anjiang hydrological model and HBV model were applied to predict the future runoff of Qingjiang Watershed under A2 and B2 scenarios. The preformance of the one-way coupling approach in simulating the hydrological impact of climate change in the Qingjiang watershed is evaluated, and the change trend of the future runoff of Qingjiang Watershed under the impacts of climate change is presented and discussed.     

Quasisecular cyclicity in the climate of the Earth’s Northern Hemisphere and its possible relation to solar activity variations

Paleoclimatological reconstructions of temperature of the Earth’s Northern Hemisphere for the last thousand years have been studied using the up-to-date methods of statistical analysis. It has bee indicated that the quasisecular (a period of 60–130 years) cyclicity, which is observed in the climate of the Earth’s Northern Hemisphere, has a bimodal structure, i.e., being composed of the 60–85 and 85–130 year periodicities. The possible relation of the quasisecular climatic rhythm to the corresponding Gleissberg solar cycle has been studied using the solar activity reconstructions performed with the help of the solar paleoastrophysics methods.     

A classification scheme for Earth’s critical zones and its application in China

As the thin layer at the Earth's terrestrial surface, the critical zone(CZ) ranges from the vegetation canopy to the aquifer or the interface between saprolite and bedrock and varies greatly in space. In the last decade, much attention has been paid to the establishment of Critical Zone Observatories(CZOs) that focus on various aspects of CZ science over different time scales. However, to the best of our knowledge, few studies have explicitly contributed to CZ classification or regionalization;thus, the spatial patterns of similar CZs have not been clearly identified. This study proposed a three-category CZ classification scheme by integrating environmental factors that greatly affect the transfer of energy and mass in the Earth's near-surface environment and thus dominate CZ formation and evolution, i.e., climate, parent material, soil type, groundwater table depth,geomorphology and land use. The main goal was to highlight the zonality of these driving forces, of which the high-category classification units were overlaid to delineate the CZ boundaries. The CZ regionalization of China was performed as a case study,resulting in 44 major regions(1 st category), 100 submajor regions(2 nd category) and 1448 regions(3 rd category). The spatial distributions and driving factors of the ten largest regions were identified, followed by a simple comparison of the CZO network.Then, the proposed CZ regionalization was compared with recent studies on regionalization in China to evaluate its successes and weaknesses. By linking together CZ studies from the last decade, we advocate that a theoretical framework integrating the CZ evolution processes with ecological functions acts as one of the frontiers of CZ science. Our study demonstrates that the proposed three-category CZ classification scheme effectively identifies the spatial variations in CZs and could thus be further applied in other areas to advance terrestrial environmental research and provide decision support for the sustainable management of natural resources.     

Possible impact of interplanetary and interstellar dust fluxes on the Earth’s climate

This article considers the process of entry of cosmic substance into the Earth’s atmosphere and the further evolution of the formed extraterrestrial aerosol. It is shown that meteorite-derived aerosol generated in the atmosphere may affect the Earth’s climate in two ways: (a) particles of meteoric haze may serve as condensation nuclei in the troposphere and stratosphere; (b) charged meteor particles residing in the mesosphere may markedly change (by a few percent) the total atmospheric resistance and, thereby, affect the global current circuit. Changes in the global electric circuit, in turn, may influence cloud formation processes. The obtained results argue for the fact that the meteoric dust in the Earth’s atmosphere is potentially one of the important climate-forming agents. It is shown that the amount of interstellar dust in the Earth’s atmosphere is too small to have a considerable affect on atmospheric processes.     

Preliminary study on isostatic anomaly and recent tectonic stress field-Taking East China Sea and its eastern marginal seas as an example

Introduction The research of present-day tectonic stress and the mechanism of strain plays an important role in tectonic physics, because the stress and strain affect the tectonic action on the plate bounda-ries and inside the plates. This action should be reflected in geometric field of deformation and in some geophysical fields such as gravitational, geothermal and seismic field as well, for instance, some researchers have investigated the tectonic movement and tectonic stress field in the E…     

Equilibrium thallium isotope fractionation and its constraint on Earth’s late veneer

Equilibrium isotope fractionation of thallium(Tl) includes the traditional mass-dependent isotope fractionation effect and the nuclear volume effect(NVE). The NVE dominates the overall isotope fractionation, especially at high temperatures. Heavy Tl isotopes tend to be enriched in oxidized Tl^3+-bearing species. Our NVE fractionation results of oxidizing Tl^+ to Tl^3+ can explain the positive enrichments observed in ferromanganese sediments. Experimental results indicate that there could be0.2–0.3 e-unit fractionation between sulfides and silicates at 1650 ℃. It is consistent with our calculation results,which are in the range of 0.17–0.38 e-unit. Importantly,Tl’s concentration in the bulk silicate Earth(BSE) can be used to constrain the amount of materials delivered to Earth during the late veneer accretion stage. Because the Tl concentration in BSE is very low and its Tl isotope composition is similar with that of chondrites, suggesting either no Tl isotope fractionation occurred during numerous evaporation events, or the Tl in current BSE was totally delivered by late veneer. If it is the latter, the Tl-contentbased estimation could challenge the magnitude of late veneer which had been constrained by the amount of highly siderophile elements in BSE. Our results show that the lateaccreted mass is at least five-times larger than the previously suggested magnitude, i.e., 0.5 wt% of current Earth’s mass. The slightly lighter 205 Tl composition of BSE relative to chondrites is probable a sign of occurrence of Tlbearing sulfides, which probably were removed from the mantle in the last accretion stage of the Earth.     

Introduction to China’s Earthquake Emergency Response System

Following the M_S6.4 earthquake that occurred on May 21, 2021 in Yangbi, Yunnan, China, the earthquake emergency response system (EERS) responded immediately. The real-time software delivered many seismic parameters that provided a preliminary assessment of the earthquake. The 24-hour on-duty staff and scientific researchers revised these parameters and produced more detailed reports to understand the cause of the earthquake and the potential damage, which provided valuable information for emergency rescue operations and earthquake situation assessment. Emergency personnel were dispatched immediately to the earthquake site to observe the aftershocks, investigate the damage, and guide and assist in the relief efforts. This paper describes the EERS response to the Yangbi earthquake to demonstrate the characteristics of the system and discuss the potential for further improvement.     

GPS time-series and its response to M_S=8.1 Kunlunshan earthquake

Introduction With the implementation of the National Climbing Program and ″Crustal Movement Obser- vation Network of China″, the GPS observation has extended widely. At present, GPS monitoring network consists of 25 reference stations, 56 movable stations and more than 1000 regional sta- tions. The reference stations begin their continuous GPS observations from the middle of March 1999. The research in this paper analyzed the law for the coordinate variation of each reference station…     

Seismic response to electromagnetic sounding of the Earth’s lithosphere

The seismic catalogues of 1967?C2008 for the Bishkek geodynamical test site are analyzed for the purpose of studying the response of seismic activity to the electromagnetic sounding of the Earth??s crust during two series of field experiments with high-power controlled sources. The first series of the experiments, which were carried out in 1982?C1990, utilized the pulses provided by a magnetohydrodynamic (MHD) generator. The sounding signals in the second series of the experiments (2000?C2005) were generated by the capacitor-thyristor source ERGU 600-2. In these experiments, temporal variations of the set of statistical parameters characterizing the seismicity, which are typically used in the studies of the background and transient modes of seismicity, were investigated in a selected spatial domain within 150 km from the current electrodes. In terms of time, the analysis was conducted on two levels of detail. The study on a temporal scale of a few years was focused on the variations that preceded, accompanied, and followed the series of the experiments, while the day-scale analysis considered variations that were observed within 10 days after each sounding event. The day-scale analysis yields the following results. The slope of the frequency-magnitude diagram of the earthquakes (b value) during the sounding events is substantially larger than its background value. The slope of the graph gradually becomes gentler within about a day and a half after termination of sounding. The seismic activity slightly enhances during the interval of sounding and abates after its termination to a minimum, which corresponds to the interval of decreasing b value. This character of variations in seismicity differs from the scenario previously established for other transitional seismic regimes. The analysis on a temporal scale of a few years revealed variations in the studied parameters of the seismicity, some of which fall in both sounding intervals of 1983?C1990 and 2000?C2005. However, these variations are not unique; their character and durations suggest their being associated with the processes of preparation and after effects of the strong earthquakes that occurred in the vicinity of the sounding dipole.     

Joy’s law and its features according to the data of three sunspot catalogs

This paper investigates the trend towards an increase in the tilt of sunspot groups with increasing latitude (Joy??s law) and the relationship between the features of this law and solar activity parameters. In addition to the known data of the Mount Wilson and Kodaikanal observatories, the analysis uses the Pulkovo database of solar activity, which allows for the estimation of the reliability of the conclusions obtained by other authors from the first two catalogs. It is shown that Joy??s law is manifested in all three data series and has many features in common. In particular at latitudes above 25?C30°, the tilt of sunspot groups is not linearly dependent on latitude and displays a slight decrease. However, some features of this law found previously in the data of the first two observatories (e.g., a decrease in its strength with an increase in the strength of the solar cycle) are not confirmed by our analysis.     

Rising grain prices in response to phased climatic change during 1736–1850 in the North China Plain

Grain price volatility during historical periods is regarded as an important indicator of the impact of climate change on economic system, as well as a key link to adjust food security and social stability. The present study used the wheat prices in Baoding Prefecture, China, during 1736–1850 to explore connections between climatic transition and grain price anomalies in the North China Plain. The main findings were as follows:(1) The grain price change showed an apparent correspondence with climatic transition. The period 1781–1820 was a transition phase, with more extremes and decreased precipitations when the climate shifted from a warm phase to a cold one. Corresponding with the climatic transition, the grain price during 1781–1820 was characterized by that the mean of the original grain price series was significantly higher(lower) than the previous(later)phase, and the variance and anomaly amplitude of the detrended grain price series was the highest during 1736–1850.(2) The correspondence between grain price extremes and drought events occurred in phases. Five grain price extremes occurred following drought events during 1781–1810, while extreme droughts were the direct cause of the grain price spike during 1811–1820.(3) Social stability affected by climate change also played an important role in the grain price spike between 1811 and 1820. Paralleling the pathway of "precipitation-grain production-grain price", climate change could have an impact on grain price via the pathway of "precipitation-grain production-grain price-famine-uprising-grain price", as shown during the Tianli Uprising in 1813. These findings could contribute to an improved understanding of the interaction between climate change and human society during the historical period.     

Focal mechanism solutions and its tectonic significance in the trench of the eastern South China Sea

Introduction South China Sea (SCS) is located in the convergence zone between Euro-Asian plate, Pacific plate (Philippine plate) and Indian plate. Interactions of three plates made the crust of this region suffer tectonic stress in many directions and made the South China Sea be in the complex environ-ment of the tectonic stress. There are four different marginal types in the surrounding of the South China Sea: The tectonic zone of the rifting margin in the north of SCS, the NS direct…     

Geology and geochemistry of the Bingdaban ophiolitic mélange in the boundary fault zone on the northern Central Tianshan Belt,and its tectonic implications

The properties and tectonic significance of the fault bound zone on the northern margin of the Central Tianshan belt are key issues to understand the tectonic framework and evolutionary history of the Tianshan Orogenic Belt. Based on the geological and geochemical studies in the Tianshan orogenic belt, it is suggested that the ophiolitic slices found in the Bingdaban area represent the remaining oceanic crust of the Early Paleozoic ocean between the Hazakstan and Zhungaer blocks. Mainly com-posed of basalts, gabbros and diabases, the ophiolites were overthrust onto the boundary fault be-tween the Northern Tianshan and Central Tianshan belts. The major element geochemistry is charac-terized by high TiO2 (1.50%-2.25%) and MgO (6.64%-9.35%), low K2O (0.06%-0.41%) and P2O5 (0.1%-0.2%), and Na2O>K2O as well. Low ΣREE and depletion in LREE indicate that the original magma was derived from a depleted mantle source. Compared with a primitive mantle, the geochemistry of the basalts from the Bingdaban area is featureded by depletion in Th, U, Nb, La, Ce and Pr, and unfrac-tionated in HFS elements. The ratios of Zr/Nb, Nb/La, Hf/Ta, Th/Yb and Hf/Th are similar to those of the typical N-MORB. It can be interpreted that the basalts in the Bingdaban area were derived from a de-pleted mantle source, and formed in a matured mid-oceanic ridge setting during the matured evolu-tionary stage of the Northern Tianshan ocean. In comparison with the basalts, the diabases from the Bingdaban area show higher contents of Al2O3, ∑REE and HFS elements as well as unfractionated incompatible elements except Cs, Rb and Ba, and about 10 times the values of the primitive mantle. Thus, the diabases are thought to be derived from a primitive mantle and similar to the typical E-MORB. The diabases also have slight Nb depletion accompanying no apparent Th enrichment compared with N-MORB. From studies of the regional geology and all above evidence, it can be suggested that the diabases from the Bingdaban area were formed in the mid-oceanic ridge of the Northern Tianshan ocean during the initial spreading stage.     

Preliminary study on isostatic anomaly and recent tectonic stress field——Taking East China Sea and its eastern marginal seas as an example

On the basis of the reality of recent tectonic movement and discarding such a viewpoint that the isostatic adjust-ment only results from excessive or insufficient compensation,we have discussed the tectonic stress causing ine-auality and regarded the isostatic anomaly as a load on the earth‘s interior,thus the earth‘s inner stress can be cal-culated.The research results show that in the East China Sea and its eastern marginal seas the change of the verti-cal stress derived from the isostatic gravity anomaly is more marked than that of the horizontal stress.Along the Ryukyu trench there is an enhancement of vertical stress by 5MPa,which evidently reflects the effect of plate subduction.On contrary,along the island are to the northwest of the trench the vertical stress weakens by about5MPa.The horizontal stresses in eastern and western parts are obviously different,the east westward stress on the oceanic crust σx is negative(while the pressure is positive)but on the continental crust in positive.These facts indicate the effect of compression between plates.     

Nitrogen storage and allocation in China’s forest ecosystems

Forests are important parts of terrestrial ecosystems and play a leading role in regional and global nitrogen(N) cycles.Detailed assessment of N storage and allocation in China's forests is critical to improve the accuracy of regional or global N estimates and to guide policy-makers in the formulation of scientific and effective N management measures. However, the fore stN storage at national scale remains unclear. Based on 4420 forest field-investigated data, we investigated the N storage allocation in China's forests, explored the spatial patterns and influence factors. The data included vegetation information on various organs(i.e., leaf, branch, stem, and root) and soil information at different depths(0-30 cm and 0-100 cm). The total N storage in China's forest ecosystems was 14.45±8.42 tN hm~(–2); 0.86±0.51 tN hm~(–2)(5.95%) in vegetation and 13.59±8.40 tN hm~(–2)(94.05%) in soil(0–100 cm). The storage and allocation of N varied significantly across various regions and forest types. For different ecological regions, N storage varied from 10.34 to 23.11 tN hm~(–2), and the allocation ratio of N storage between vegetation and soil(0–100 cm) varied from 0.03 to 0.16. For different forest types, the N storage varied from 12.87 to 18.32 tN hm~(–2), and the allocation ratio of N storage between vegetation and soil(0–100 cm) varied from 0.03 to 0.09. The spatial patterns relative to N storage and allocation in forests were different. Climate was the primary factor influencing the spatial variation in forestN storage, while soil texture was the main factor influencing the spatial variation in N allocation. These first estimates of N storage and allocation ratio in China's forests are keys for improving the fitting accuracy of regional N cycle models and provide a reference for regional management of forestN.     

Impact of China’s Air Pollution Prevention and Control Action Plan on PM2.5 chemical composition over eastern China

China promulgated the Air Pollution Prevention and Control Action Plan(the Action Plan) in 2013 and developed stringent control measures to mitigate fine particulate matter(PM_(2.5) pollution.Here,we investigated the PM_(2.5) chemical composition changes over eastern China associated with the Action Plan during 2013-2017 using satellite-based PM_(2.5) chemical composition data derived using CMAQ simulations and satellite inputs.The PM_(2.5) concentrations decreased considerably during this time as a result of the reductions in all chemical species in PM_(2.5).The population-weighted mean concentrations over eastern China decreased from 11.1 to 6.7μgm~(-3) for SO_4~(2-),13.8-13.1μgm~(-3) for NO_3~-,7.4-5.8μgm~(-3) for NH_4~+,9.9-8.4μgm~(-3) for OM,4.6-3.8 μg m~(-3) for BC and 12.9-9.6 μg m~(-3) for other species in PM_(2.5).SO_4~(2-) had the largest reduction of 40%,while NO_3~-had the lowest reduction of 5%,resulting in a greater fraction of NO_3~-and a smaller fraction of SO_4~(2-) in PM_(2.5).Among the three key regions,Beijing-Tianjin-Hebei had the largest reduction in PM_(2.5) and its chemical compositions.The decrease in SO_4~(2-) concentrations was in line with the reduction of SO_2 emissions,and the major driver of the SO_2 emission reductions was the industrial sector.The decrease in NO_3 concentrations was limited because the decrease in SO_2 emissions and the stable NH_3 emissions facilitated the formation of NO_3~- from HNO_3,which partiall_y offset the reduction in NO_x emissions driven by the power sector.To mitigate PM_(2.5) pollution more effectively,future efforts are needed to reduce NH_3 emissions.     

Interannual variability of Antarctic Oscillation and its influence on East Asian climate during boreal winter and spring

1 Introduction Antarctic Oscillation is a major mode of Southern Hemispheric (SH) extratropical atmospheric circula- tion. The SH Annual Mode represents a zonally sym- metric exchange of mass between polarward of 60°S and 40°S[1], therefore AAO indicates both the intensity of circumpolar low and zonal mean west wind at mid-high latitudes in SH. Positive phase of AAO tends to deepen circumpolar low and enhance west wind at mid-high latitudes in SH. Many studies show that AAO has bar…