Abstract:Carbon neutralization is a hot topic in the world, and geoscience can play an important role in this field. Internationally, the Intergovernmental Panel on Climate Change, the International Energy Agency, the Energy Transition Commission, and policy advisory groups at the national level have proposed a series of models and scenarios for possible ways to reduce CO₂ emissions, indicating that to achieve carbon neutrality, electricity will replace fossil fuels as the main carrier of global energy. In the context of global urgent need for CO₂ emission reduction, it is very important for geosciences to provide geological solutions to achieve the climate objectives of the Paris Agreement. Carbon dioxide emission reduction involves many scientific issues, including heat storage and geothermal, dry hot rock, hydropower energy storage, compressed air energy storage, nuclear energy, carbon capture and storage, hydrogen economy and mineral raw materials for energy transformation. Earth science can help reducing carbon dioxide emissions through the following ways:first, to describe the rock mechanics characteristics of geological body, so as to store CO₂ and establish green energy system in the decarbonization area; secondly, to further reveal the origin and genesis of the mineral resources needed for electric vehicle batteries and wind turbines; thirdly, to expand the scale from small laboratory to pilot, industrialization and commercialization; and fourthly, to understand the public's attitude towards underground decarbonization technology to ensure the safety of the project. The goal of carbon neutralization provides new opportunities for geoscience research, and the future development needs support from various aspects. Achieving carbon neutrality requires improving awareness of the key role of geoscience in achieving decarbonization, developing technologies, building industrial chains, and achieving sustainable development.

Abstract:China is rich in graphite mineral resources, and the existing exploration and research results are mostly concentrated in the central and eastern regions. However, the present situation and prospecting potential of graphite mineral resources in Tibet are not clear. With the investment of mineral exploration work, the first large graphite deposit in the Sanjiang area of Tibet was discovered, namely the Qingguo graphite deposit. Its resource is 1.0694 million tons of fixed carbon minerals (indicated and inferred) at average grade of 8.40%. Through detailed field geological survey and borehole geological logging, the basic geological characteristics of the deposit have been clarified. The emplacement age of the ore-bearing pluton was determined by zircon U-Pb geochronology. Combined with the carbon isotopic composition, the genesis and metallogenic age of the deposit were studied. Orebodies in the deposits are hosted in a monzogranite pluton as thick tabular and irregular shape, and graphite is present as ball or irregular rains. These ore-bodies might be formed as the product of recrystallization during the magmatic hydrothermal activity when the coal-bearing strata of the Lower Carboniferous Kagong Formation were captured by monzogranite magma. The U-Pb age of ore-bearing monzogranite yielding (244.7±1.3)Ma indicates its emplacement during Middle Triassic, which represents the magmatic age and metallogenic age. The discovery of many graphite deposits and prospects in Tibet indicate that there is good exploration potential of graphite resources, especially in the Sanjiang area.

Abstract:The northern margin of Qaidam Basin is a well-known ultra-high pressure metamorphic belt with abundant mineral resources. The orogenic gold deposits are widely distributed in the northern Qaidam. This paper focuses on the study of the geological characteristics, temperature and isotopes of ore-forming fluids of the gold deposits in northern Qaidam. The results show that the orogenic gold deposits are mainly distributed in the shear zones of the Mesoproterozoic, Cambrian and Ordovician metamorphic rocks, and most ore bodies is related to the NW-trending structures. Besides, the mineralization temperature of most gold deposits is bimodal, and only a few gold deposits exhibit monomodal in temperature, indicating that multi-phase fluids were involved in the mineralization process. The δ¹⁸O_H2O-SMOW (-1.7‰-10.31‰) and δD_V-SMOW(-113.8‰﹣-41.6‰) of the ore-forming fluid indicate that the metamorphic fluid is influenced by magmatic water and atmospheric water. The δ³⁴S of gold-containing sulfides (pyrite and galena) ranges from 0.5‰ to 11‰, mainly in the range of 5‰ to 9‰, ²⁰⁶Pb/²⁰⁴Pb from 18.238 to 19.296, ²⁰⁷Pb/²⁰⁴Pb from 15.547 to 15.773, and ²⁰⁸Pb/²⁰⁴Pb from 37.918 to 38.978, which indicates that the ore-forming materials are derived from the mantle-upper crust, and are affected by magmatism to some extent. The tectonic evolution and metallogenic ages reveal that three gold metallogenic events occurred in the northern Qaidam during 426-376 Ma、357-330 Ma and 288-246 Ma.

Abstract:Aiming at the needs of geological disaster investigation and assessment in loess area, a multi-dimensional extraction method of landslide single information based on UAV tilt photographic image and flight control data was explored. Rich information of the Jiajiacun landslide was quantitatively extracted from DEM, DOM and real scene 3D model obtained by image processing, including its slope shape, slope, relative height difference, vegetation coverage, longitudinal slope ratio, surface area and source volume. The stratigraphic lithology and regional structure are analyzed by using relevant geological data. Combined with the regional meteorological data, the spatial and temporal distribution of annual average rainfall of Jiajicun landslide was analyzed, which provides an efficient and accurate qualitative and quantitative reference for the accurate assessment of its stability and risk.

Abstract:Coal measure gas is an important part of unconventional natural gas field, and it is also a hot spot of unconventional natural gas research in recent years. Summing up the research progress of coal measure gas and clarifying the important scientific problems to be solved are of great significance for perfecting the geological theory of coal measure gas and promoting the exploration and development of coal measure gas. The current research progress of coal measure gas can be mainly concluded in the following five aspects:a. summary of six basic geological characteristics of paragenic reservoir of coal measure gas based on the sedimentary characteristics of coal measure gas; b. preliminary classification of paragenesis and assemblage mode of coal measure gas, and analysis of four major controlling factors of coal measure gas and their allocation relationship; c. analysis of the genesis of the superimposition of coal measure gas, and raise of identification and evaluation method of the superimposed coal measure gas system and the geological elements controlling the compatibility of the superimposed gas bearing system; d. summary of the theoretical research, technical methods, recognition technology of production contribution, optimal combination of production layers and "desserts" evaluation of co-exploration and co-production in coal measure gas; and e. some exploratory researches in evaluation of coal measure gas resource and prediction of its prospects. Based on the summary of the present research, four important scientific problems to be solved urgently in the study of coal measure gas are put forward as follows:a. the fine reservoir description and reservoir removability evaluation of coal measure gas; b. evaluation of coal measure gas resources and optimization of its prospects; c. the evaluation technology of development sweet areas (sector) of coal measure gas; and d. co-production compatibility evaluation of superimposed coal measure gas system. The solution of these problems will contribute to the efficient development of coal measure gas resources and the development of its geological theory.

Abstract:The latest progress of the studies on reservoir's fine description of petroleum in China is shown as the following 12 aspects, fine earthquake technology-based complex structure study, complex buried hill lithology recognition technology, fine prediction technology of reservoir through combination of well data and seismic data, characterizing techniques for fissures of low permeable reservoir, classification of microscopic pore structure of conglomerate reservoir, interlayer insulation features based on the data of dense well pattern, water flooded layer interpretation of conglomerate reservoir, reservoir variation law during the development of oilfields, flow channel identification technology of conglomerate reservoir, quantitative classification evaluation of low permeable reservoir, configuration modeling of fault block oil reservoir and multidisciplinary comprehensive characterization technique of residual oil, etc. At present, in the fine description research of reservoir there exist the following eight aspects of problems, mainly including interpretation of microstructures (especially low sequence faults) failing to meet oilfield development needs, many difficulties in single sand body boundary features and interwell prediction, fracture characterization and geological modeling, many difficulties in the quantitative prediction of carbonate fractured-vuggy reservoir, logging interpretation of complex reservoirs still needing to be studied continuously, difficulties in inflow channel identification, a single remaining oil characterization method difficult to meet the production needs, and management status of fine reservoir description result that cannot meet the work requirements. Finally, the development trend in the fine description of reservoir is pointed out.

Abstract:Carbonatite-hosted endogenetic rare earth element (REE) deposits related to alkaline rocks are very important in light rare earth resources in China and even in the world. At present, controversies for the evolution mechanism of ore-forming fluids for carbonatite-hosted REE deposits are mainly among crystallization differentiation, liquid immiscibility (melt-melt, melt-fluid and fluid-fluid immiscibility) and hydrothermal metasomatic alteration. Crystallization differentiation can gradually enrich the incompatible REEs in the residual melt phase until the REE minerals are formed. Immiscibility can lead to selective enrichment of REEs in one of the two or multiple-phases formed after immiscibility, resulting in REE mineralization. The hydrothermal fluids formed in the late stage of ore-forming fluids evolutionary process have metasomatic reaction with the early-formed minerals or surrounding rocks and release anions (anion clusters) such as F^-, (CO₃)^2- and (SO₄)^2-, which can form complexes with REEs in the hydrothermal aqueous solution, and finally recrystallize or precipitate REE minerals in appropriate ore-hosting structures under suitable external conditions. Each of the above three viewpoints has its own theoretical basis, but they are more or less inadequate in the explanation of some geological phenomena or experimental geochemical simulation results of carbonatite-hosted REE deposits. The previous study results shown that there are a large number of melt inclusions, melt-fluid inclusions and CO₂-rich fluid inclusions in carbonatite-hosted REE deposits. In the past, most of these inclusions decrepitated or were leaked before reaching the total homogenization status when heated at 101325 Pa by using conventional high temperature heating stages, such as Linkam TS1400XY and Linkam THMS600, which greatly restrict our understanding of the evolutionary process of ore-forming fluids in high temperature magmatic stage and medium-high temperature magmatic-hydrothermal stage for this type of REE deposits. In addition, studies on the contents variation characteristics and geochemical behavior of REEs in the ore-forming fluid evolutionary process is mainly through the Raman spectroscopy analysis of the components of inclusions, as well as the whole rock geochemical analysis of ore bodies and surrounding rocks, and there is still a lack of in-situ microanalysis data about the element contents of individual inclusions. In the future, for melt inclusions, melt-fluid inclusions, and CO₂-rich fluid inclusions that trapped in this type of deposits, in-situ high temperature and high pressure microthermometry experiments by employing hydrothermal diamond-anvil cell together with in-situ LA-ICP-MS microanalysis of trace elements contents in individual inclusions, are supposed crucial to reveal its evolution mechanism of ore-forming fluids.

Abstract:Soil heavy metal pollution is currently the most prominent soil environmental pollution problem in China. The total national soil pollution exceedance rate is 16.1%, mainly heavy metal pollution, including cadmium point exceedance rate of 7%, which is threatening on the food security. We introduced the status of soil heavy metal pollution, sorted the traditional and emerging methods and technologies of soil heavy metal pollution detection and analysis, and described the technical trends such as the detection of heavy metals at the molecular level and the application of biosensing technology to the detection of heavy metals. Considering the complexity of the soil system, the focus of future development should be to achieve the intersection of geoscience, chemistry, and biology, strengthen the theoretical research on the bioavailability of heavy metals, form a biological effectiveness analysis and detection indicators for soil heavy metals pollution, and make the evaluation method scientific, standardized, and unified. Make further efforts to promote integration of national heavy metals analysis standards with international standards.

Abstract:Zhaheba ophiolite is a significant ophiolite complex in Eastern Junggar, consisting mainly of peridiotite, basalt, layered gabbro, plagiogranite and chert. Among them, the peridiotite is mainly composed of harzburgite, herzolite, and minor dunite. The average contents of clinopyroxene in herzolite are Cr₂O₃ 1.11%, Al₂O₃ 4.77%, MgO 16.99%, CaO 21.84%, SiO₂ 50.00%, and the accessory mineral chromium spinel falling within the high-Al types has lower average contents Cr₂O₃ 40.35%、Cr^# 0.53 but higher Al₂O₃ 24.10%, MgO 13.23% and Mg^#(0.62),which indicate that it was formed during the extension of Zhaheba ocean in MOR environment. While the element contents of chrome spinels in massive chromites changes little with average contents of Cr₂O₃ 55.45%、Al₂O₃ 10.88%, MgO 11.98% and Mg^# 0.60, which fall in high-Cr type fields and belong to SSZ type of chromites. Clinopyroxenes in herzolite is characterized by typical structures of melted residue and melt-rock reaction, and orthopyroxene in harzburgite kept bastitic pseudomorphs and unaltered enstatites, but chrome spinel accessory minerals show corrosion features. The melting residual structure of monocline is a manifestation of the melting and chromium release of chromium-bearing minerals, and also a structural indicator of the partial melting degree of peridotite increasing and the evolution towards more magnesium rich direction, which may have limited contribution to the formation of Cr-rich chromite. The peridotite contains monoclinopyroxene, olivine and textures newly generated from melt-rock reaction. The role of fluid and volatiles in the melt-rock reaction cannot be ignored. Based on the above studies, the relationship among the content differences of Cr^#、Mg^# and Al₂O₃ of chromite and tectonic settings of ophiolite, and its influence factors are discussed. It is concluded that mantle convection and subduction of Kalamaili ocean led to the enrichment of the high-Al chrome spinels in MOR environment and forming of massive chromites.

Abstract:The Jianlong Cu-W deposit, as a newly discovered one in southern Jiangxi Province, is located at the convergent zone of the eastern Nanling EW-trending tectono-magmatic belt and Yushan depression of the western Wuyishan uplift belt. The ore bodies, including mineralized quartz vein and greisen, are hosted in the inner and outer contacts between Fozishan granite and Sinian epimetamorphic rocks. Based on the LA-ICP-MS zircon U-Pb and molybdenite Re-Os isochron dating, the ages of the granule biotite granite and the molybdenite in greisen were accurately determined. The weighted average age of single-grain LA-ICP-MS zircon U-Pb of granite is 154.2±1.7 Ma, and the Re-Os isochron ages of molybdenite is 155.9±1.2 Ma. The study results suggest that diagenesis and mineralization occur almost at the same time. The age of diagenesis and mineralization of the deposit is determined to be Late Jurassic, similar to the Huamei'ao, Zhangjiadi and Yanqian in this area. Combined with the previous research data, it is further confirmed that the tungsten polymetallic deposits in the eastern part of Nanling Mountains were mainly formed at 170-150 Ma. The rhenium content of molybdenite in the ore ranges from 6.484×10^-6 to 21.346×10^-6. Combined with sulfur isotope analysis, it is considered that the ore-forming materials of the deposit originate from crust-mantle mixing.

Abstract:The Mengqiguer uranium deposit in the Ili Basin is the largest sandstone-hosted one discovered in recent years. In order to research the source of ore-forming materials, the properties of ore-forming fluids and the metallogenic environment of the deposit, a geochemical studies on trace elements and sulfur isotope of the pyrites (the gangue minerals in Xishanyao Formation and Badaowan Formation, which closely related to ore minerals such as uraninite and coffinite) were carried out systematically. The results show that the REEs of pyrite in each sample exhibits a similar distribution pattern,that is,LREE is significantly more enriched than HREE (La_N/Yb_N=4.27-9.82), with strong negative Eu anomaly (δEu=0.50-0.71) and no Ce anomaly (δCe=0.93-1.04).The Co contents of pyrite range from 2.1×10^-6 to 26.7×10^-6, Ni from 19.5×10^-6 to 79.30×10^-6,the ratio of Co/Ni from 0.07 to 0.88, and As from 8.90×10^-6 to 95.60×10^-6 higher than the average As content of the continental crust. The sulfur isotope composition of pyrite has a relatively wide range of variation, i.e. δ³⁴S_CDT ranging from -17.30‰ to 3.90‰, with the change range of 21.20‰. Combined with characteristics of REEs, trace elements and sulfur isotope composition of pyrites and regional metallogenic setting,it is suggested that pyrite in this deposit is of sedimentary origin and was formed in a low temperature reduction environment. It is concluded that the sulfur of pyrite mainly originates from coal and sedimentary sulfide with microbial genetic characteristics, and pyrites and charcoal debris (organic matters) provide reductants for redox reactions during uranium mineralization.

Abstract:The Ehenaobaotu tonalite is outcropped in the northern part of the Meilaotewula SSZ-type ophiolite of the Erenhot-Hegenshan suture zone in Xi Ujimqin Banner of Inner Mongolia. Based on the study of petrology, geochemistry and zircon LA-ICP-MS U-Pb geochronology, the genetic type and tectonic setting of the tonalite were determined, and the final closure time and subduction process of the Erenhot-Hegenshan ocean basin of the Paleo-Asian Ocean were discussed. The tonalite is characterized by high SiO₂, Al₂O₃, Na₂O, Sr and low K₂O, Y contents, enrichment of Rb, Ba, Sr large ion lithophile elements and LREE, and depletion of Nb, Ta, Ti, P high field strength elements and HREE. There is no pronounced Eu anomaly. The lithological and geochemical characteristics show that the Ehenaobaotu pluton is a high Si adakite (HSA) formed in island arc, and was derived from patial melting of the intra-oceanic subductingd oceanic crust and sediment and subsequently reaction with overlying mantle wedge peridotite. Its U-Pb LA-ICP-MS dating yields (305.6±1.5) Ma and suggests that the Ehenaobaotu pluton was formed during Late Carboniferous. Combined with the study of spatio-temporal evloution of the Carboniferous ophiolites and Carboniferous-Permian island arc magmatic rocks in the Erenhot-Hegenshan suture, it is assumed that the Erenhot-Hegenshan oceanic basin of the Paleo-Asian Ocean was in the process of oceanic subduction characterized by intra-oceanic subduction during the Carboniferous-Early Permian.

Abstract:The geological survey revealed that several paleo-volcanic edifices related to Emeishan basalt were identified in the Zhaojue-Meigu area on the western margin of Yangtze Block, which provides an excellent window for studying their eruption cycles and modes. The rock types of paleo-volcanic edifices are mainly composed of thick basalts, small amounts of pyroclastic rocks and volcanic clastic lavas. They have the characteristics of explosive facies, lava overflow facies and volcanic depression facies. Systematic geological profile suggest that there are three rapid eruption cycles (without any interval) and 25 volcanic rhythms during the formation of the Emeishan basalt Formation. Among them, the eruption patterns of the first and third cycles are dominated by the explosive facies and lava overflow facies, while the second cycle is dominated by the overflow phase. The systematic confirmation and study of the paleo-volcanic edifices reveal the volcanic eruption pattern and cycle rhythm characteristics of Emeishan large igneous province, which provides important data for the further study of the Wupo copper deposits in the western margin of Yangtze Block.

Abstract:The Yaocun pluton in Southern Anhui Province, lithologically consisting mainly of medium-to coarse-grained syenogranite in its centre and fine-grained porphyritic syenogranite on its margin, is outcropped around the northeastern Jiangnan orogeny of the Lower Yangtze region. This paper reports detailed study results of its the LA-ICP-MS zircon U-Pb dating, major elements, trace elements, whole-rock Nd isotopic compositions and zircon Hf isotopic compositions. LA-ICP-MS zircon U-Pb ages show that the Yaocun pluton, as the product of magmatic activity in the late Yanshanian period, was emplaced at 127.6±1.4Ma. The studies of petrography and geochemistry of this rock indicate that it is A-type granite, and is characterized by rich silica, high iron, high zircon saturation temperatures, enrichment of Rb, Th, U, K and Pb, depletion of Ba, Nb, Sr and Ti, and significant negative Eu anomalies (Eu/Eu^*=0.22-0.46). Its ε_Nd(t) and ε_Hf(t) values range from -6.2 to -5.7 and from -13.9 to -5.0 respectively, and the calculated two-stage model ages (T_DM2) of Nd and Hf isotopes from 1439 Ma to 1532 Ma and from 1508 Ma to 2062 Ma respectively. Combined with the results of regional geological research, it is suggested that the Yaocun pluton might be formed by the Mesoproterozoic crust remelting under extension-tension environment after the subduction of the Paleo-Pacific plate during the Early Cretaceous.

Abstract:Ion-adsorption type REE deposits is hosted in regolith of Neoproterozoic epimetamorphic rocks in South Jiangxi, China. LA-ICP-MS U-Pb dating of detrital zircons from two metamorphic tuff samples of the originally identified Kuli Formation of Qingbaikou System in a mine area yielded the harmonic ages of 88 groups and 110 groups respectively. They are predominantly Neoproterozoic and have ages ranging from 810 to 667 Ma with three age peaks at ca 798 Ma (n=55), 737 Ma (n=127) and 680 Ma (n=6). There are also a few Meso-to Paleoproterozoic zircon grains with ages scattering from 2.85 Ga to 1.08 Ga. The dating results probably suggest that the sedimentary age of the tuffite may be Nanhua Period. It is speculated that the provenance may be volcanic-sedimentary rocks of late Qingbaikou Period to Nanhua Period in the eastern part of Jiangnan orogenic belt (northeast Jiangxi-southern Anhui-western Zhejiang). The super thick marine volcanic-clastic sediments of the same period in southern Jiangxi might be formed in the rift basin after the breakup of the ancient continent of South China, and the sedimentary time of the secondary rift basin in southern Jiangxi is about 810-727 Ma.

Abstract:Intermediate-basic volcanic rocks are largely distributed in Greater Khingan Mountains of Heilongjiang Province, and the determination of their ages is of great significance to understanding the regional tectonic evolution and petrogenesis of the Mesozoic volcanic belt in the Great Xing'an Range. Based on the 1:50000 regional geological and mineral resources survey in the study area, the LA-ICP-MS zircon U-Pb geochronology, petrology and petrogeochemistry of the intermediate-basic volcanic rocks previously attributed into the Middle-Late Jurassic Tamulangou Formation were systematically studied. Zircon U-Pb dating of the two trachyandesite samples and one basaltic andesite sample yields (185.8±8.1)Ma, (196.8±2.1)Ma and (196.3±2.7)Ma respectively, which indicates that there exists a set of early Jurassic intermediate-basic volcanic rocks in the Tamulangou Formation. These Early Jurassic volcanic rocks belong to metaluminous, mainly high-K calc-alkaline series generally enriched in large ion lithophile elements (such as Ba、K、La、Ce、Sr、Zr) and LREE, but depleted in high field strength elements (such as Th、Nb、P、Zr、Ti) and HREE. Combined with the regional tectonic evolution, it is conclude that the early Jurassic intermediate-basic volcanic rocks were formed in an active continental margin setting related to the southward subduction of the Mongol-Okhotsk oceanic plate beneath the Erguna Massif during the Early Jurassic.

Abstract:The Linhe Depression of Hetao Basin is a NE-SW trending Meso-Cenozoic arc-shaped strike-slip pull basin. Based on the combination of microfauna fossils, logging response characteristics (including the method of acoustic wave time difference to determine unconformity) and seismic response characteristics of unconformity, an unconformity within the Lower Cretaceous was identified. The unconformity is distinguished by the overlying Guyang Formation and underlying Urta Formation. The former is generally developed throughout the basin, and its thickness does not change much, and the latter with thickness decreasing from northwest to southeast as a whole is mainly distributed in two small sags close to the Langshan fault. The time and depth conversion results of the seismic data show that the thickness of the Urta Formation in the south is greater than that in the north. The thickest formation in the south is about 800 meters, and the thickest formation in the north is about 600 meters. After the deposition of the Urta Formation, the basin was affected by the Middle Yanshan Movement and subjected to the northwest-southeast compression. Due to the squeezing effect, the strata were uplifted and suffered erosion, resulting in the internal unconformity within the Lower Cretaceous. The unconformity is characterized by gradually changing from parallel unconformity to angular unconformity from northwest to southeast. Combined with the causes of the unconformity and the change of the thickness of the strata, the structural evolution of the basin in the early Cretaceous can be divided into three stages:the fault depression stage in the early Early Cretaceous, the uplift and erosion stage in the middle Early Cretaceous and the weak extension depression stage in the late Early Cretaceous.

Abstract:The Fengtai-Yejituo fault is one of the major faults in the Tangshan area. Its west side is Yahongqiao sag, while its east side is Tangshan rise. There is an obvious difference in the thickness of the Quaternary strata between both sides of the fault. Based on the boreholes on both sides of the fault, this paper makes a preliminary study on its activity since the Quaternary period. Combined with drilling information, the composition of rocks, and the results of the optically stimulated luminescence(OSL) and ¹⁴C dating, the Quaternary stratigraphic framework was established according to the magnetic stratigraphy of the boreholes PZK14 and PZK20 which are hanging on the upper and lower plates of the Fengtai-Yejituo fault. The results show that the "boulder-clay layer" at the bottom of the two holes was Neogene sediments. The borehole PZK14 revealed that the buried bottom boundary depth of the Lower Pleistocene, the Middle Pleistocene, the Upper Pleistocene and the Holocene was 387 m, 114 m, 71 m and 6 m, respectively. The borehole PZK20 showed that the buried bottom depth of the Lower Pleistocene, the Middle Pleistocene and the Upper Pleistocene sediments was 155 m, 73 m and 36m respectively, without the Holocene sediments. The activity of Fengtai-Yejituo fault gradually enhanced in the early Pleistocene and its activity rate increased from the early 5.4 cm/ka to 13.9 cm/ka. In the Middle Pleistocene, its activity is basically in a state of stagnation, with an activity rate of 1.0 cm/ka. After the Late Pleistocene, it was reactivated and became more intense active, with activity rate of 54.5 cm/ka.

Abstract:The Maniao-Puqian fault trending east-west, as the major one controlling the Qiongshan earthquake registered 7.5 magnitude on Richter scale in 1605, is a major active fault in the northern Hainan area. Hence, its activity's measuring is critical for crustal stability evaluation and for geological hazard forecast in the northern part of Hainan Island. Various methods were used to determine the distribution of the eastern part of this fault, including remote sensing images interpretation, fault landform mapping, high-density electrical detecting and cross-section drilling validation. The results show that it is spatially composed of 8 north-dipping or south-dipping NEE-trending normal faults (F2-1~F2-8), constituting the three-graben and two-barrier structure, and inheriting the multi-stage activities from the faults before the Pliocene. Five Holocene active faults (F_2-1, F_2-4, F_2-6, F_2-7 and F_2-8), two pre-Quaternary faults (F_2-2 and F_2-5) and one early Miocene fault (F_2-3) were identified by chronological tests. Moreover, the vertical movement rate of F_2-1,F_2-7 and F_2-8 was 0.43-1.79 mm/a, while that of F_2-4 and F_2-6 between 0.12-0.33 mm/a since Holocene. The above research shows that the structures in this area are all in an active state, which has a great influence on the future engineering construction, and the monitoring efforts must be strengthened.

Abstract:Lying in the east of the Yangtze plate, southern Anhui experienced multiple periods of magmatic activity and tectonic deformation related to the subduction of the Paleo-Pacific Plate during the late Mesozoic. As an important structure controlling the tectonic framework, the NE-trending fault has undergone multiple stages of evolution since the Indosinian period. Previous studies mainly focused on the active stages of faults, and there were disputes on the active periods of each stage, which restricted the in-depth study of tectonic evolution in southern Anhui and even eastern China since Mesozoic. The field investigation reveals that sinistral strike-slip deformation of the NE-trending fault in southern Anhui is actually a high-angle translational fault. The inversion of the paleo-tectonic stress field indicates that it was formed in the NNE-SSW compression environment. Zircon U-Pb geochronology and stratigraphic cutting relationship indicate that its sinistral strike-slip age is at the end of Early Cretaceous. Combined with previous studies on paleontology and stratigraphy, it is believed that its sinistral strike slipping was formed in 121-110Ma, and may be related to the movement direction change of the Izenizaki Plate at the end of the Early Cretaceous.

Abstract:The study on the geochemical evolution of elements in the red weathering crust in tropical karst area is helpful to the understanding of the theory of weathering and soil-forming of carbonate rocks. Two typical weathering profiles of carbonate rocks in northern Vietnam were selected to analyze the material source and evolution characteristics of major elements in the red weathering crust overburden of carbonate rocks under tropical climate conditions. The results show that regardless of the element ratio analysis of Ti/Zr, the element pair covariant analysis of Hf-Zr, Nb-Ta and Sm-Nd, or the normalized analysis of the average value of upper crustal elements (UCC), the weathering crust of the two profiles all show the character of in-situ residual, that is, the two profiles are weathering products of carbonate rocks in situ. In the weathering process of carbonate rocks, the leaching of CaO and MgO is obvious, and the enrichment of Al₂O₃ and Fe₂O₃ occurs, indicating that both sections have undergone a strong weathering process, but the dolomite and limestone sections have certain differentiation. The weathering profile of dolomite stone in northern Vietnam exhibits a stable Ti-Fe co-enrichment from the bedrock to the topsoil, while the growth rate of Fe in the limestone profile is significantly higher than that of Ti. The crust over dolomite stone underwent intense weathering process. Though its desilication was weaker than that of limestone weathering profile, its aluminum enrichment was much stronger than that of limestone profile. The evolution law of migration coefficient indicates that the components of feldspar (potassium feldspar, sodium feldspar, etc.) or secondary minerals (illite, etc.) in the two profiles were gradually decomposed in the process of weathering, while the stable elements such as Al, Fe and Si were continuously enriched in the weathering profiles.

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