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231.
The North Qilian orogenic belt is a typical plate suture zone, which is studded with numerous different sizes of fragments of micro-continental crust consisting of pre-Sinian metamorphic rocks and the North Qilian orogenic belt provides important study carrier for studying the pre-orogenic tectonic process of the North Qilian. The relatively complete volcanic-clastic-carbonate rocks formation of Zhulongguan Group, Changchengian System, Mesoproterozoic are distributed in the Kawa-Qiqing area, Western North Qilian orogenic belt. Geochemical characteristics of the Aoyougou Group basalts in the North Qilian indicated that the contents of major element were relatively stable, high K2O contents(4.27%~6.07%), TFe2O3(10.49%~13.01%),TiO2(1.96%~2.90%)and middle MgO(5.37%~6.71%,Mg# 48~51), CaO(2.57%~5.51%)content. Thus, the Aoyougou Group basalts belong to potassium alkaline basalt. The contents of Cr and Ni of the basalts decreased with the decreasing of Mg#, and there was a positive correlation between CaO and CaO/Al2O3, Furthermore, the Eu anomaly of samples was slightly negative, high contents of high field strength elements (HFSE, Nb, Ta, Ti), and the ratios of Gd/Yb(2.5~3.0), Zr/Y(8.6~10.2), Ta/Yb(0.96~1.23), Ti/Yb(5 074~6 021), Zr/Yb(81~97), Ce/Nb(1.87), Zr/Nb(6.41)indicated that the Aoyougou Group basalts had obvious OIB-type magmatic affinity. In combination with the regional geological background, the study results showed that Aoyougou Group alkaline basalt generated from deep enrichment mantle similar to the source of OIB, with fractional crystallization of olivine and monoclinic pyroxene and a certain degree of contamination of continental crust in the process of magmatism, formed in the background of continental rift, might response to the Proterozoic Columbia supercontinent rifting, which further provides important petrological evidences for the relationship between North China Craton rifting events and Columbia supercontinent rifting during Proterozoic. 相似文献
232.
Atmospheric circulation anomaly is a direct cause of weather and climate change. In the past, most researches for the relationship between Weather Type (WT) and precipitation have mainly focused on the subjective classification and diagnosis. Compared to the subjective analysis, objective classification uses more consistent index and standard unification, thus, we can get more WTs, and it has been widely used in many areas. By using daily 12UTC Sea Level Pressure (SLP), Precipitable Water (PW), and 700 hPa wind speed (UV700) data from ECMWF’s Interim Reanalysis, the classification of WTs over China was performed with the method of obliquely rotated T-mode principle component analysis. WT and its link to precipitation over China were further analyzed. The results show that the influence of different WTs on precipitation is not uniform over China, and also show distinctly difference in different seasons. A common feature is that WTs great impact on the regions and months with large precipitation, while less impact on regions and months have with less precipitation. In addition, precipitation trends originating from WT intensity changes are much more deterministic, significant, and predictable than trends from WT frequency changes. 相似文献
233.
皖南宁国竹溪岭钨银矿床是近年来发现的一个与花岗岩类有关的矽卡岩型矿床,准确厘定其成矿年龄及相关侵入岩体的年龄有利于深入认识区域岩浆作用与成矿作用的规律。本文在矿床地质调查的基础上,应用现代同位素定年技术开展地质年代学研究,获得矿床矿石中的辉钼矿Re-Os模式年龄为142.7±2.1 Ma和142.9±2.1 Ma,相关侵入岩体花岗闪长岩、花岗斑岩和花岗闪长斑岩的LA-ICP-MS锆石U-Pb年龄分别为139.8±1.8 Ma、143.3±1.9 Ma、140.2±1.7 Ma,显示矿床的成矿年龄与侵入岩体的成岩年龄基本一致,为燕山晚期早白垩世。矿床矿石中的辉钼矿的Re含量指示成矿物质来源于地壳和地幔的混合;与成矿相关侵入岩的稀土元素和Hf同位素组成特征指示成岩物质也具有壳幔混源特征,显示成矿物质来源与成岩物质来源具有一致性。区域岩浆岩和矿床的对比表明,与之相邻的长江中下游地区、浙西地区和赣东北地区乃至整个华南地区这一时期发生了大规模的岩浆作用和钨锡多金属成矿作用,显示扬子板块在此阶段处于岩浆–成矿大爆发时期,皖南地区的成矿时代对应于华南中生代三次大规模岩浆作用和成矿作用的第二阶段。 相似文献
234.
Water cycle includes natural water circulation and social economic system water cycle. The concept of virtual water provides a new method and means for studying social water circulation. This paper is based on the theory of water circulation in social and economic system, using input-output analysis method quantitatively describes the Tarim River basin of social water cycle paths and analysis of water resources management in Tarim River basin sustainable development process of the key issues. The results show that the main sectors of virtual water export in the Tarim River Basin are agriculture, petroleum, natural gas and food industry. Agricultural water accounts for more than 98% of total water consumption, most of which is transferred to the food and textile industries, and the food industry export water from the agricultural sector. Shandong Province is the largest virtual water transport area in the Tarim River Basin. The main sector of virtual water input in the Tarim River Basin is the metallurgical industry. Finally, in view of the problems arising from the inter-industrial and inter-regional social water circulation in the Tarim River basin, the paper puts forward the ways and strategies of regulating agricultural and industrial water use in the Tarim River Basin. 相似文献
235.
A CE-5T1 spacecraft completed a high-speed skip re-entry to the earth after a circumlunar flight on October 31, 2014. In addition to the strapdown inertial navigation system (SINS), a lightweight GPS receiver with rapid acquisition was developed as a navigation sensor in the re-entry capsule. The GPS receiver effectively solved the poor accuracy problem of long-term navigation using only the SINS. In contrast to ground users and low-earth-orbit spacecraft, numerous factors, including high altitude and kinetic characteristics in high-speed skip re-entry, are important for GPS positioning feasibility and were presented in accordance with the flight data. GPS solutions started at nearly 4900 km orbital altitude during the phases of re-entry process. These solutions were combined by an inertial measurement unit in a loosely coupled integrated navigation method and SINS navigation initialization. A simplified GPS/SINS navigation filter for limited resources was effectively developed and implemented on board for spacecraft application. Flight data estimation analyses, including trajectory, attitude, position distribution of GPS satellite, and navigation accuracy, were presented. The estimated accuracy of position was better than 42 m, and the accuracy of velocity was better than 0.1 m/s. 相似文献
236.
Mapping hourly dynamics of urban population using trajectories reconstructed from mobile phone records 总被引:2,自引:0,他引:2
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Understanding the spatiotemporal dynamics of urban population is crucial for addressing a wide range of urban planning and management issues. Aggregated geospatial big data have been widely used to quantitatively estimate population distribution at fine spatial scales over a given time period. However, it is still a challenge to estimate population density at a fine temporal resolution over a large geographical space, mainly due to the temporal asynchrony of population movement and the challenges to acquiring a complete individual movement record. In this article, we propose a method to estimate hourly population density by examining the time‐series individual trajectories, which were reconstructed from call detail records using BP neural networks. We first used BP neural networks to predict the positions of mobile phone users at an hourly interval and then estimated the hourly population density using log‐linear regression at the cell tower level. The estimated population density is linearly correlated with population census data at the sub‐district level. Trajectory clustering results show five distinct diurnal dynamic patterns of population movement in the study area, revealing spatially explicit characteristics of the diurnal commuting flows, though the driving forces of the flows need further investigation. 相似文献
237.
建立温度与硼同位素变化的关系是研究沉积硼酸盐成岩-变质作用中硼同位素地球化学行为的关键,这有助于准确认识硼酸盐δ11 B值所代表的地质意义.本文以自然产出的三方硼砂和钠硼解石为材料,结合热分解特征研究了不同热作用过程中硼同位素变化.200℃下硼酸盐经历结晶水的脱水反应,此过程中三方硼砂和钠硼解石δ11B值分别由6.48±0.14‰降低到5.41±0.27‰和由-13.27±0.11‰降低到-15.93±0.23‰.1‰~3‰的硼同位素变化与自然界观察到的由脱水作用形成的次生硼酸盐比原生硼酸盐δ11 B值低2‰~4‰的现象一致.200~300℃间经历羟基的脱水过程,伴随着1‰~2‰的硼同位素降低,此过程中三方硼砂和钠硼解石δ11 B值分别由5.41±0.27‰降低到3.73±0.26‰和由-15.93±0.23‰降低到-17.11±0.11‰.300~670℃间硼酸盐经历物相转化过程,三方硼砂和钠硼解石δ11B值分别由3.73±0.26‰升高到4.59±0.08‰和-17.11±0.11‰升高到-16.08±0.20‰.此过程1‰的硼同位素升高是由硼-氧骨架结构改变造成的.本实验结果可以指示沉积硼酸盐的形成过程,以及埋藏过程中的硼同位素变化规律.硼酸盐脱水过程中会形成具有更高δ11 B值的流体,其可能显著影响内生硼矿的硼同位素组成,因此讨论硼同位素地质意义不能与海相-非海相环境中的硼同位素组成进行简单对比,需要考虑流体演化过程中的硼同位素变化. 相似文献
238.
Zhu Yalin Ma Chi Tan Kun Chen Juxiang Wang Yixian 《Geotechnical and Geological Engineering》2021,39(8):5479-5492
Geotechnical and Geological Engineering - Due to the complexity of the interaction between the geogrid and the soil interface in high earth-rock dams, the method of replacing the grid with steel... 相似文献
239.
Natural Hazards - Frequent occurrences of drought stress caused by dry weather create severe destroy in apple yield and quality in North China. Although appropriate drought stress is beneficial to... 相似文献
240.