25 years of continental deep subduction

This year marks the 25th anniversary of the discovery of coesite in metamorphic rocks of supracrustal origin. This initiated a revolution of the plate tectonics theory due to intensive studies of ultrahigh pressure metamorphism and continental deep subduction. The occurrence of coesite was first reported in 1984 by two French scientists, C. Chopin and D.C. Smith,     

Re-Os dating of auriferous pyrite from the Zhenyuan super-large gold deposit in Ailaoshan gold belt, Yunnan Province, Southwestern China

Zhenyuan gold deposit is the largest super large gold deposit in the Ailaoshan gold belt,but its precise mineralization age is still lack.Re-Os isotopic age of the auriferous pyrite from the Zhenyuan gold deposit was determined by using a high-resolution inductively coupled plasma mass spectrometry(HR-ICP-MS).The pyrite samples were decomposed in carius tubes,Os was separated by distillation and Re was extracted by acetone,respectively.The results show that the Re-Os isochron age is 229±38 Ma(MSWD=2.0,confidence level is 95%),with an initial 187 Os/188 Os value of 0.68±0.24 and a corresponding Os value of 442±91.The Re/Os ratios of the pyrite vary from 40.8 to 100.5.The data suggest that at least one important ore-forming event was occurred during Indosinian epoch,and the ore-forming materials probably derived from mixed sources of crustal and mantle,while the later dominated.The Ailaoshan composite orogen experienced complicated evolutional processes,including formation of Precambrian-Early Paleozoic basement,subduction and orogenesis of Late Paleozoic era,collisional orogenesis of Late Hercynian-Indosinain epoch,and extensional or striking orogenesis of Yanshainan-Cenozoic epoch.The polycycle tectonic evolution and magmatism in this area caused multi-stage and superposition metallization characteristics of the Zhenyuan gold deposit:the mineralization probably occur mainly during the Indosinian collisional orogeny,while the minor gold ores of altered granite-porphyry and altered lamprophyre may be formed in the late superposition metallization.     

Searching for the remains of subducted continental slabs

On the basis of oceanic geological and geophysical observations the global plate tectonics theory was put forward in the late 1960s.It inherited the essence of mobilism of continental drift and sea-floor spreading,caused a revolution of earth sciences in the twentieth century.But plate tectonics cannot satisfactorily explain the complicated geological phenomena of continents,it fails in elucidating the formation and evolution process of continents.Therefore,the formation and evolution of continents have been the hot topics explored by earth scientists in recent years.As far as China is concerned,the opening and closing of Tethys are related to the formation,evolution,and compressional reformation of Chinese continent in the Mesozoic period,hence have important implications.     

基于文献计量的国际极地研究进展分析

通过汤森路透Web of Science收录的极地研究论文计量分析可以看出,20世纪90年代以来国际上关于极地研究的文献大量涌现。论文发表量与地域优势有着密切关系,南半球国家的极地研究论文大多是关于南极的,环北极国家对北极的研究明显多于南极。当前极地科学研究主要涉及地球科学多学科、海洋学、生态学、气象与大气科学、环境科学、生物学、自然地理学、地球化学与地球物理学等学科领域。极地研究的热点问题包括气候变化、北极生态系统和环境污染、南极地质构造和磷虾等。建议密切关注国际极地研究的发展态势与进展,鼓励我国海洋学家、气象学家、地质学家、环境生态学家、生物学家、社会经济学家和政治学家有计划有步骤地开展研究,为我国赢取更广泛参与极地事务的发展空间。     

甘蒙北山地区板块构造演化与铜多金属矿成矿系列研究

结合板块构造理论和成系列概念,提出了成矿系列新的研究方法。甘蒙北山地区位于哈萨克斯坦板块和塔里木-中朝板块交汇部位,其板块构造演化分为前震旦纪古板块活动时期、震旦一泥盆纪现代体制板块活动时期和石炭-二叠纪裂谷活动时期,不同构造单元演化阶段控制了不同的含矿建造、成矿作用时空分布及演化序列和矿床共生组合。按照板块构造演化及其与铜多金属矿成矿作用时空分布和成矿作用演化序列的关系,划分出北山地区铜多金属矿古大陆区（缘）成矿系列,洋缘火山带成矿系列、岛弧-弧后盆地成矿系列和裂谷带成矿系列。     

重庆市大学生求知行为调查研究

通过自编的求知行为调查问卷，对重庆市296名大学生进行了调查．调查结果表明，大学生的学习动机由强到弱依次为内部动机、成就动机、社会动机和外部动机；在学习行为方面，低年级学生满怀理想却缺少实际行动，自主性和独立性不强；高年级学生趋于务实，想学更多的实用知识，以便为就业做好准备；大学生更为看重知识的个体价值，把促进自我的发展和完善以及取得事业成功作为衡量知识价值的重要标准．     

Silurian to Devonian foreland basin in the south edge of Tarim Basin

Based on the theory of plate tectonics, combin-ing with the isotopic dating of ophiolite, igneous and volcan-ics, geochemical test, rare earth element analyze and seismicinterpretation, this paper studies the pre-Carboniferous tec-tonics and sedimentary formation of the south edge of theTarim Basin and proves that there exists the Kunlun Oceanunder tensional tectonics during the Sinian and Cambrian inthe south edge of the Tarim Plate. After that, due to the colli-sion orogenesis, there formed the peripheral foreland basinin the south edge of Tarim. The Upper Silurian and Devo-nian molasses sedimentary system superposed on the Sinianand Middle Silurian passive margin flysch sedimentary sys-tem and formed the bivariate structure of the foreland basin.And at the same time, based on the field geology and seismicinterpretation, we have identified that the formation of theSilurian and Devonian have the character of half depositwhich shows thick in the south area and thin in the north,and the pre-Carboniferous thrust compression tectonics re-mained in the foreland thrust belt, which further demon-strates that there existed the Silurian and Devonian periph-eral foreland basin on the south edge of the Tarim Basin.     

如何提高初中英语课文教学的效果

不少学生在初中学了三年英语以后,还不能认读与课文难易程度相当的短文,这是因为他们的老师在初中的 英语课文教学中只重视句型教学,忽视英语课文的教学;或只重视语法分析,忽视了活用课文的语言材料。应通过课文 教学培养学生的听、说能力,通过课文教学培养学生读、写的能力,为学习高中阶段的英语的打好基础。介绍了课堂中 的具体的做法。     

合肥市初三学生耐力素质年度变化特征研究

本研究通过对合肥市199名初三学生的耐力素质进行学年度追踪测试,分析年度变化特征及各阶段的变化特征,探索中考体育加试政策对初三学生耐力素质变化的驱动作用。主要研究结论:初三学生耐力素质在上学期有显著性提高,寒假期间也有明显提高;中考体育加试前一直在提高,在中考体育加试时达到最高峰,但随后则一直明显下降;整个初三学年学生的耐力素质水平变化非常显著。     

湖南沃溪金矿断裂构造动力成矿研究

文章重点探讨了断裂构造动力成矿的机制及模式,并以此为基础,全面分析了湖南沃溪金矿含金石英脉中金及SiO_2在断裂构造动力成矿作用下垂向和侧向上的积聚过程,指出断裂构造动力成矿作用与该矿床的形成演化有密切关系。     

新疆北部金、银、铜化探元素的分形研究及其找矿意义

根据板块构造的观点,划分新疆北部地壳的大地构造单元,应用分形基本和分数维的计算方法,计算出新疆北部地壳中金,银,铜的分数维,分析分数维的特征,研究其在板块构造和找矿等方面的意义。元素含量具有分形特征,分数维值的大小和矿化程度有关,最后指出新疆北部的找矿方向。     

初高中数学教学衔接浅议

不少中学生升入高中后难以适应,觉得数学比初中难学,付出的时间多,成绩却不理想。高中数学和初中数学在教材内容、教学方式、思维层次和教学方法上都不同,文章就这几个方面论述了初高中数学的教学衔接。     

中国地体构造研究进展综述

地体构造理论被应用于中国地质的具体实践已经１５年并取得了丰硕的成果,主要表现在：１．中国境内地体构造的划分,２．地体构造理论上的创新,包括地体定义的完善;板块、微板块、地体、板惩、覆体五者之间的理论甄别,地体的古板块单元重建和古地体古大洋研究;地体拼贴增生和裂解离散的形式和过程,地体运动形成的沉积盆地和能源矿产;３．方法学上的进展,主要有古地磁喾综合地球物理学、微古生物及其对含放射虫硅质岩的新认识     

护理专科学生实习焦虑的成因调查及应对方式

目的：了解大学专科护生临床实习期间压力源、应对方式以及焦虑状况,并分析其影响因素。方法：采用问卷调查法收集资料,对87名大学专科护生实习中后期进行调查。结果：87名大学专科护生压力水平处于中低水平,前10位压力源为未来的择业与就业、带教老师的态度、接触传染性疾病、对紧急情况的应变能力、临床学习期间的考试、带教老师的评价、出现差错的可能等,12.94%的护生存在焦虑情绪。护生多采用较为积极的应对方式。结论：注重专科护生临床实习期间的引导,以帮助护生尽快适应临床学习。     

初高中物理学习方法的衔接

针对初、高中物理学习衔接"不畅",指出了学习高中物理的障碍,以及初、高中物理学习方法的不同,提出了学好高中物理的途径。首先是排除学习中的数学障碍;其次尽快适应高中物理的学习方法,提高学习能力。     

Ore-forming event and geodynamic setting of molybdenum deposit at Wenquan in Gansu Province, Western Qinling

The Wenquan molybdenum deposit is associated with a Triassic granite in this area. The Wenquan granite is enriched in LILE and LREE, poor in HFSE, and has significantly higher contents of alkali （K2O＋Na2O） and Sr, Ba than those of the island arc volcanic rocks. These geochemical characteristics are similar to post-collisional granites in high K calc-alkaline series. Studies of major elements, trace elements, REEs and chronology of the Wenquan pluton show that, in the geodynamic transition stage of continent-continent convergence to extension, the partial melting of the enriched lithospheric mantle generated the basaltic magma and triggered the partial melting of the thickened lower crust which produceded the acidic magma, and the Wenquan pluton was formed by mixing of the two magmas. Molybdenite Re-Os isotopic dating gave Os model ages of 212.7±2.6 Ma to 215.1±2.6 Ma with a weighted mean of 214.1±1.1 Ma, and an Re-Os isochron age of 214.4±7.1 Ma. These ages are close to K-Ar ages （223 to 226 Ma） and a SHRIMP zircon U-Pb age （223±7 Ma） for the Wenquan granite within the error range, but relatively younger. This implies that the Mo mineralization occurred in a late stage of the magmatic intrusion, and the metallogenesis took place in the transition stage from syn-collision to post-collision in the tectonic setting of the Qinling Orogenic Belt （QOB） after continental collision between the North China Block （NCB） and the South China Block （SCB）. This process is also corresponding to the geological events of metamorphism and deformation in South Qinling, closure of the Mian-Lue oceanic basin, and exhumation of the Dabie-Sulu ultrahigh-pressure metamorphic rocks. The large-scale continent-continent collision between NCB and SCB in the middle Triassic triggered significant crustal thickening and exhumation of subducted slab. In the late Triassic, the tectonic setting was transformed to the transition stage from collision to extension. Materials from the asthenospheric mantle would ascend into the root of the lower crust, which could induce partial melting of the lower crust and generate Mo-enriched granitic magma. The ore-forming elements enriched in the fluid derived from the condensation and fraction of the magma resulted in the Mo mineralization. The Mo deposits in the QOB are mainly formed in two episodes, namely 220± Ma and 140± Ma. The two episodes of metallogenesis were developed in the tectonic transition settings from compression to extension, but they were in the different stages of the tectonic evolution. The occurrence of the Wenquan Mo-bearing pluton indicates that the Triassic tectonic-magmatic belt of Western Qinling is another favorable region for Mo mineralization in the QOB. Therefore, it is significant to pay more attention to evaluation of the ore-forming potentiality in the Triassic granites in Western Qinling.     

大学低年级与高中阶段英语写作者元认知策略对比及发展研究

通过定量和定性研究方法对比大学低年级和高中阶段英语写作者在元认知策略上的使用情况及发展趋势。研究发现：第一,两个阶段的写作者的元认知策略意识都较弱,均不太擅长使用元认知策略;第二,相比较而言,高中阶段写作者使用元认知策略的频率高于大学低年级阶段写作者;第三,对照高中阶段,大学低年级写作者的元认知策略及写作能力呈现逆向发展趋势。     

一种RSA公开钥密码体制的分级加密设计

通过对ＲＳＡ算法理论的研究，推广了某些基本定理。基于这些推广，设计了一套分等级加以开钥密码体制中，高等级用户掌握着“万能”解密密钥ＳＫ２。既可以低级密文进行脱密，也可以对高级密文进行脱密。而低级用户只能对低级密文进行脱密。     

羌塘盆地侏罗纪双壳类化石组合及古环境

海相侏罗系是羌塘盆地发育最全、分布最广泛的沉积层系.作者根据详细的野外地质工作,收集了典型剖面的岩相、沉积构造和大量的化石,并借鉴、总结前人的研究成果,对该区双壳类生物地层进行较系统的、全面的分析研究,划分了五个双壳类化石组合:Camptonectes auritus-Pteroperna costatula,Eomiodon angulatus-Isognomon(Mytiloperna)bathonica,Camptonectes laminatus-Anisocardia beaumonti,Anisocardia tenera-Modiala biparta以及Gervillella aviculoides-Radulopecten fibrosus;认为该区雁石坪群的时代从巴柔期至牛津-基末里期,从而建立起生物地层格架及年代地层格架.根据沉积标志以及典型的化石组合,探讨了研究区古地理环境,并识别出滨海、潮坪、潟湖、碳酸盐台地以及碳酸盐缓坡等古沉积环境,揭示了各时期自然地理状况,对探索东特提斯地区的构造演化和双壳类的生态演变都有重要的意义.     

粤桂边境庞西垌——金山银金矿床成矿条件与形成机理

庞西垌—金山银金矿床位于广东廉江县与广西博白县的交界 ,是一个以银为主 ,含有金、铅、锌等伴生有益组分的银多金属矿床。研究表明 ,前寒武系—寒武系变质岩系是银金矿床的主要矿源层 ,其具有的高Ag和高Ag/Au比值特征 ,为本区形成以Ag为特色矿床的提供了重要的物质基础 ;燕山期英桥花岗岩为成矿热液的形成和活动提供了热源 ,驱使以大气降水含有岩浆热液的混合水循环并对围岩混合岩和花岗岩进行淋滤 ,形成成矿溶液 ;多期次活动的庞西垌—金山断裂带不仅为花岗岩浆活动提供通道 ,而且使两侧岩石产生节理和裂隙 ,有利于热液的循环、淋滤和定位 ,并直接成为矿质沉淀的场所 ;含矿断裂的热液围岩蚀变作用是矿床最后定位的决定性因素 ,矿化与硅化、绢云母化、黄铁矿化关系密切。