Damage Characteristics of Altered and Unaltered Diabases Subjected to Extremely Cold Freeze–Thaw Cycles     

Xuedong Luo  Nan Jiang  Changqun Zuo  Zhenwei Dai  Suntao Yan 《Rock Mechanics and Rock Engineering》2014,47(6):1997-2004

Altered and unaltered diabases are commonly deposited on hydrothermally mineralized slopes. To study their damage characteristics during freeze–thaw cycles, they were sampled from Cihai iron ore mine located in an extremely cold region, Xinjiang, China and examined using acoustic and X-ray diffraction experiments to analyze the differences in their main mineral components and explore their damage characteristics under freeze–thaw conditions. Based on the results of these experiments, their damage and degradation patterns were obtained and the evolution of their physical characteristics including the rock mass loss rate (L _F), rock strength loss rate (R _σ ), P-wave velocity loss rate (V _l), and freeze–thaw coefficient (K _f) was analyzed. In addition, two groups of equations were established to characterize the relationships of these physical and mechanical properties of the rock specimens with the number and temperature of freeze–thaw cycles. The results show that the mineral composition of diabase changes during its alteration, showing increased clay and calcite, and the degradation and evolution patterns of the physical and mechanical parameters (L _F, R _σ , V _l, and K _f) of the altered rocks during freeze–thaw cycles are different from those of diabase, with the altered diabase exhibiting greater damage than the diabase.  相似文献   

三网融合下气象影视的挑战与机遇     

林毅  周恩泽  邹倩倩  戴思玉 《内蒙古气象》2013,(3):44-46

随着信息媒介的不断增多,依托于传统媒体的电视气象节目也在信息风暴中受到了巨大挑战。文章介绍了气象影视所面对的问题,以及新环境给气象节目带来的机遇,并对气象节目及气象频道提出建议。  相似文献   

锦州市规划区地质环境安全评价研究     

代雅建 《地质与勘探》2024,60(1):76-87

地质环境问题是影响城市国土空间安全开发利用的重要因素,在城市规划开发阶段开展地质环境综合评价可有效控制地质灾害风险。锦州市规划区尚处于开发前期,本文基于该规划区的地质条件和开发需求,构建了地质环境安全评价指标和评价方法体系,基于主导因素综合法开展了地质环境安全综合评价。根据评价结果,锦州市规划区地质环境安全程度可划分为3级,空间分布上以相对安全区为主,其次为次不安全区和安全区。按照空间位置和区域构造稳定性、地质灾害易发性等不同成因划分为23个亚区,并指出了每个亚区安全程度主要影响因素。该评价结果反映了锦州市规划区的地质环境安全程度,确定了影响地质环境安全问题的关键因素,有助于规避该区国土空间规划开发可能面临的地质灾害风险。  相似文献   

Predicting climate anomalies:A real challenge          下载免费PDF全文

Huijun Wang  Yongjiu Dai  Song Yang  Tim Li  Jingjia Luo  Bo Sun  Mingkeng Duan  Jiehua Ma  Zhicong Yin  Yanyan Huang 《大气和海洋科学快报》2022,15(1):2-11

过去几十年,气候变化和极端气候事件造成的经济损失和灾害显著增加.虽然全球的科学家在理解和预测气候变异方面做出了巨大的努力,但当前在气候预测领域仍然存在几个重大难题.2020年,依托于国家自然科学基金基础科学中心项目的气候系统预测研究中心(CCSP)成立了,该中心旨在应对和处理气候预测领域的三大科学难题:厄尔尼诺-南方涛动(ENSO)预测,延伸期天气预报,年际-年代际气候预测,并为更加准确的气候预测和更加有效的灾害防御提供科学依据.因此,本文介绍了CCSP的主要目标和面对的科学挑战,回顾了CCSP在季风动力过程,陆-气相互作用和模式开发,ENSO变率,季节内振荡,气候预测等方面已取得的重要研究成果.未来CCSP将继续致力于解决上述领域的关键科学问题.  相似文献   

Palaeoproterozoic tectonothermal evolution and deep crustal processes in the Jiao‐Liao‐Ji Belt,North China Craton: a review     

S. Z. Li  G. C. Zhao  M. Santosh  X. Liu  L. M. Dai 《Geological Journal》2011,46(6):525-543

The Palaeoproterozoic Jiao‐Liao‐Ji Belt is located in the eastern margin of the Eastern Block of the North China Craton. In this paper, we synthesize the tectonothermal evolution and deep crustal processes in the Jiao‐Liao‐Ji Belt based on recent information. A mantle plume‐related underplating from 2.53 to 2.36 Ga is envisaged which led to the emplacement of the 2.47–2.33 Ga alkali granite plutons and mafic dyke swarms, followed by the development of the Jiao‐Liao‐Ji Rift and bi‐modal volcanism. The underplating resulted not only in different sedimentary environments in the upper crust, but also in a differentiation of the initial thermal structure in the rift. This controlled the metamorphism and style of P‐T‐t paths in the different parts of the rift. Subsequent underplating resulted in the emplacement of the A‐type Liaoji granites of ca. 2.17 Ga in the lower crust, and the formation of associated pegmatites of 2.2 and 2.0 Ga, together with the development of a bedding‐parallel extension. However, the main orogeny occurred between 1.93 and 1.88 Ga with closing of the rift, compressional deformation and high‐pressure granulite metamorphism in the southern part of the orogen. Subsequently, lithospheric blocks were possibly delaminated at ∼1.85 Ga; anorogenic magmatic rocks such as rapakivi granite, alkaline granites and syenite were intruded, and pegmatite veins and mafic dyke swarms were emplaced cross‐cutting all the earlier structural traces. We identify that the underplating styles, collision processes and delamination types in the deep lithosphere controlled the tectonothermal evolution of the crust in the Jiao‐Liao‐Ji region. Copyright © 2011 John Wiley & Sons, Ltd.  相似文献   

峰峰矿区磁西三号勘查区地温异常分析     

代尚京 《中国煤炭地质》2013,(10):40-42

磁西三号勘查区详查阶段钻孔全部进行了井温测量工作,发现区内2、4号煤层处在高温热害区内,且同一水平地温变化较大,2号煤层-800m水平地温最大差值为5.1℃,显示勘查区可能存在地温异常。通过对钻孔测温资料的分析研究,确定本区地温梯度在1.8~2.6℃/100m,与峰峰矿区基本一致;高温区的出现是由于煤层埋藏深度加大和岩浆岩侵入带来的附加热效应而导致地温增加。结果认为,本区为正常地温背景下的高温热害区。  相似文献   

Memorial to Prof. Paolo Bono 1940–2012     

James W. LaMoreaux  Marco Petitta  Giuseppe Capelli  Hai Thanh Tran 《Environmental Earth Sciences》2013,70(2):497-499

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The teratogenic effects of sediments from the Yangtze Estuary and adjacent bay, China, on frog embryos     

Huahong Shi  Jing Yuan  Zhijun Dai  Hongyi Yao 《Environmental Earth Sciences》2013,68(8):2385-2391

In recent decades, the Yangtze (Changjiang) Estuary has suffered great environmental changes due to intensive human activities in the Yangtze River basin. This study assessed the ecotoxicity of sediments from the Yangtze Estuary with the frog embryo teratogenesis assay—Xenopus (FETAX). The results showed that the sediment extracts induced multiple malformations in embryos of Xenopus tropicalis. In the embryos treated with nearshore extracts, abnormal eyes, narrow fins and hypopigmentation were the dominant phenotypes, followed by enlarged proctodeums. In these embryos, the percentages of total malformations were greater than 50 % at five sampling sites and less than 40 % at the other seven sites. However, in the embryos treated with the offshore extracts, elongation of the proctodeums was the dominant phenotype, followed by bent tails. The percentages of total malformations ranged from 25 to 45 %. Comparatively, the embryos treated with extracts from the nearshore zone showed a greater variety of phenotypes than those treated with extracts from the offshore zone. These results suggest that the sediments showed high teratogenicity to the amphibian embryos. The results also indicate that the teratogencity to X. tropicalis embryos is a useful indicator of the pollution of sediments.  相似文献   

SCI/SSCI期刊与中文权威核心期刊论文的学术价值评价——基于地理工作者的感知分析   总被引：2，自引：2，他引：2  

朱晓华  何书金  王岱  孙枫  汪德根 《地理学报》2016,71(4):680-692

进入信息全球化时代,SCI/SSCI 论文越来越成为中国各高校及科研院所等单位衡量其基础研究实力的评价标准,甚至出现“唯‘SCI/SSCI’论”的现象,中文权威核心期刊论文的学术价值评定和认可度则相应降低,这在一定程度上对中文权威核心期刊的发展造成了不小的冲击。基于探索性因子分析,构建了中文权威核心期刊论文学术价值认可度的结构方程假设模型,以地理科学工作者为例,通过验证性因子分析,实证研究了地理工作者对中文权威核心期刊论文学术价值认可度的影响因素。结果显示：① 学术成果影响力是影响中文权威核心期刊论文学术价值认可度的关键因素,科研评价和学术地位认定政策及学术影响力评价是影响中文权威核心期刊论文学术价值认可度的重要因素;② 学术成果影响力对认可度影响程度最大,其影响路径系数为0.52,其次为学术影响力评价,路径系数为0.25,科研评价和学术地位认定政策影响程度较小;③ 学术成果影响力和学术影响力评价与认可度表现为正相关关系,而科研评价和学术地位认定政策与认可度之间则表现为负相关关系。最后,提出了增强科研工作者对中文权威核心期刊论文学术价值认可度的相关对策,以期提升作者发表中文权威核心期刊论文的意愿度,来促进中文权威核心期刊的持续发展。  相似文献   

海南岛早古生代大地构造格局:来自志留纪早期碎屑锆石年代学的约束     

龙文国  周岱  柯贤忠  王晶  吴俊  张楗钰  王磊  王祥东  徐德明 《华南地质与矿产》2022,38(1):79-93

北东向乐东-定安断裂的具体位置及演化对海南岛大地构造单元划分及构造演化研究意义重大.本文采用碎屑锆石年代学方法,分析了乐东-定安断裂南西段两侧志留纪兰多维列世沉积物物源的特征及其差异,并讨论其中蕴含的大地构造意义.研究结果表明东方江边娜姆河地区志留纪兰多维列世陀烈组中碎屑锆石年龄介于1457～3124 Ma之间,显示1...  相似文献