Structural and Morphological Features of the Participation of Microorganisms in the Formation of Nb–REE–Rich Ores of the Tomtor Field (Russia)     

Dobretsov  N. L.  Zhmodik  S. M.  Lazareva  E. V.  Bryanskaya  A. V.  Ponomarchuk  V. A.  Saryg-ool  B. Yu.  Kirichenko  I. S.  Tolstov  A. V.  Karmanov  N. S. 《Doklady Earth Sciences》2021,496(2):135-138

Doklady Earth Sciences - Data indicating the important role of microorganisms in the redistribution of REEs in the weathering crust and the decisive role in the concentration of REEs during the...  相似文献   

Influence of the Growth of Earth’s Solid Core on the Effective Geodynamo     

Reshetnyak  M. Yu. 《Doklady Earth Sciences》2021,496(2):151-154

Doklady Earth Sciences - A model of the Earth’s cooling, which describes the formation of a solid core, is considered. Its formation enhances the convection due to additional energy sources...  相似文献   

The First 147Sm–143Nd Data on Rocks from the 6925.2- to 8250-m Interval of the SG-7 Superdeep Borehole (West Siberian Oil-and-Gas Province)     

Ronkin  Yu. L.  Karaseva  T. V.  Maslov  A. V. 《Doklady Earth Sciences》2021,496(2):130-134

Doklady Earth Sciences - The 147Sm–143Nd systematics of 14 samples of basalts, tuffs, silicites, and dolerites from the interval 6925.2–8250 m of the SG-7 superdeep borehole (En-Yakha),...  相似文献   

Results of the Study of Zircon (SIMS) from Granitoids of the Konstantinovskii Stock (Area of the Sukhoi Log Gold Deposit): Age,Sources, and Geological Consequences     

Rytsk  E. Yu.  Tolmacheva  E. V.  Velikoslavinsky  S. D.  Kuznetsov  A. B.  Rodionov  N. V.  Andreev  A. A.  Fedoseenko  A. M. 《Doklady Earth Sciences》2021,496(2):146-150

Doklady Earth Sciences - The results of U–Pb geochronological (SIMS) study of zircons from granitoids of the Konstantinovskii Stock located 6 km from the Sukhoi Log gold deposit are reported....  相似文献   

The Strong Earthquake in Sakhalin Island in September 13, 2020     

Konovalov  A. V.  Khanchuk  A. I.  Stepnov  A. A.  Stepnova  Yu. A. 《Doklady Earth Sciences》2021,497(1):242-245

Doklady Earth Sciences - The seismotectonic position of the strong earthquake that occurred in the southern part of Sakhalin Island on September 13, 2020, is considered. The maximum shaking...  相似文献   

Integration of zircon and apatite U–Pb geochronology and geochemical mapping of the Wude basalts(Emeishan large igneous province):A tool for a better understanding of the tectonothermal and geodynamic evolution of the Emeishan LIP     

Jia-Nan Fu  Franco Pirajno  Fan Yang  Espine Shivute  Yi-Zhan Sun  Ning Ai  Kun-Feng Qiu 《地学前缘(英文版)》2021,12(2):573-585

Radiogenic isotopic dating and Lu–Hf isotopic composition using laser ablation-inductively coupled plasma-mass spectrometry(LA-ICP-MS)of the Wude basalt in Yunnan province from the Emeishan large igneous province(ELIP)yielded timing of formation and post-eruption tectonothermal event.Holistic lithogeochemistry and elements mapping of basaltic rocks were further reevaluated to provide insights into crustal contamination and formation of the ELIP.A zircon U–Pb age of 251.3±2.0 Ma of the Wude basalt recorded the youngest volcanic eruption event and was consistent with the age span of 251-263 Ma for the emplacement of the ELIP.Such zircons hadε_Hf(t)values ranging from7.3 to+2.2,identical to those of magmatic zircons from the intrusive rocks of the ELIP,suggesting that crust-mantle interaction occurred during magmatic emplacement,or crust-mantle mixing existed in the deep source region prior to deep melting.The apatite U–Pb age at 53.6±3.4 Ma recorded an early Eocene magmatic superimposition of a regional tectonothermal event,corresponding to the Indian–Eurasian plate collision.Negative Nb,Ta,Ti and P anomalies of the Emeishan basalt may reflect crustal contamination.The uneven Nb/La and Th/Ta values distribution throughout the ELIP supported a mantle plume model origin.Therefore,the ELIP was formed as a result of a mantle plume which was later superimposed by a regional tectonothermal event attributed to the Indian–Eurasian plate collision during early Eocene.  相似文献   

Field study on the behavior of pre-bored grouted planted pile with enlarged grout base     

Zhou  Jia-jin  Yu  Jian-lin  Gong  Xiao-nan  El Naggar  M. Hesham  Zhang  Ri-hong 《Acta Geotechnica》2021,16(10):3327-3338

This paper presents the results of field tests performed to investigate the compressive bearing capacity of pre-bored grouted planted (PGP) pile with enlarged grout base focusing on its base bearing capacity. The bi-directional O-cell load test was conducted to evaluate the behavior of full scale PGP piles. The test results show that the pile head displacements needed to fully mobilize the shaft resistance were 5.9% and 6.4% D (D is pile diameter), respectively, of two test piles, owing to the large elastic shortening of pile shaft. Furthermore, the results demonstrated that the PHC nodular pile base and grout body at the enlarged base could act as a unit in the loading process, and the enlarged grout base could effectively promote the base bearing capacity of PGP pile through increasing the base area. The normalized base resistances (unit base resistance/average cone base resistance) of two test piles were 0.17 and 0.19, respectively, when the base displacement reached 5% D_b (D_b is pile base diameter). The permeation of grout into the silty sand layer under pile base increased the elastic modulus of silty sand, which could help to decrease pile head displacement under working load.

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Basal stability analysis of braced excavations in anisotropic and non-homogeneous undrained clay using streamline velocity fields     

Huang  Maosong  Wang  Hongyu  Tang  Zhen  Yu  Jian 《Acta Geotechnica》2021,16(4):1175-1186

Acta Geotechnica - A basal heave stability analysis in anisotropic and non-homogeneous undrained clay by using the kinematic approach of limit analysis is presented. The proposed failure mechanism...  相似文献   

全民所有自然资源资产管理考核评价机制与方法研究     

周玉  邹朝晖 《上海国土资源》2021,(1):90-94

本文采用对比分析与归纳分析法,在明确全民所有自然资源资产管理考核评价机制定位的基础上,充分借鉴和参考现有相关考核评价制度的设计思路,围绕“考核谁、谁来考、怎么考、考什么、结果怎么定、结果怎么用”等关键问题,从考核评价对象和实施主体、考核评价方式和实施、考核评价结果应用、考核评价内容和指标体系构建、考核评价结果评定方法等方面,提出构建全民所有自然资源资产管理考核评价机制和方法的思路,为推进生态文明建设和自然资源资产产权制度改革提供支撑。  相似文献   

Landslide susceptibility zonation method based on C5.0 decision tree and K-means cluster algorithms to improve the efficiency of risk management   总被引：1，自引：0，他引：1  

Zizheng Guo  Yu Shi  Faming Huang  Xuanmei Fan  Jinsong Huang 《地学前缘(英文版)》2021,12(6):243-261

Machine learning algorithms are an important measure with which to perform landslide susceptibility assessments,but most studies use GIS-based classification methods to conduct susceptibility zonation.This study presents a machine learning approach based on the C5.0 decision tree(DT)model and the K-means cluster algorithm to produce a regional landslide susceptibility map.Yanchang County,a typical landslide-prone area located in northwestern China,was taken as the area of interest to introduce the proposed application procedure.A landslide inventory containing 82 landslides was prepared and subse-quently randomly partitioned into two subsets:training data(70％landslide pixels)and validation data(30％landslide pixels).Fourteen landslide influencing factors were considered in the input dataset and were used to calculate the landslide occurrence probability based on the C5.0 decision tree model.Susceptibility zonation was implemented according to the cut-off values calculated by the K-means clus-ter algorithm.The validation results of the model performance analysis showed that the AUC(area under the receiver operating characteristic(ROC)curve)of the proposed model was the highest,reaching 0.88,compared with traditional models(support vector machine(SVM)=0.85,Bayesian network(BN)=0.81,frequency ratio(FR)=0.75,weight of evidence(WOE)=0.76).The landslide frequency ratio and fre-quency density of the high susceptibility zones were 6.76/km2 and 0.88/km2,respectively,which were much higher than those of the low susceptibility zones.The top 20％interval of landslide occurrence probability contained 89％of the historical landslides but only accounted for 10.3％of the total area.Our results indicate that the distribution of high susceptibility zones was more focused without contain-ing more"stable"pixels.Therefore,the obtained susceptibility map is suitable for application to landslide risk management practices.  相似文献