大陆板内玄武岩数据挖掘:成分多样性及在判别图中的表现

通常认为,大陆溢流玄武岩(CFB)、裂谷玄武岩(CRB)、板内玄武岩(WPB)均产于板内构造环境,其地球化学特征与OIB类似,源于富集的下地幔,与地幔柱的活动有关。本文利用GEOROC数据库对全球CFB、CRB和WPB数据进行挖掘,发现上述三类玄武岩判别图投图几乎落入了全部的构造环境域,有些甚至主要落入MORB和IAB区,而不是落入WPB区。结果表明原先的玄武岩判别图的判别功能值得商榷,尤其对大陆玄武岩来说,许多判别图都存在问题。全体CFB、CRB和WPB的地球化学成分变化巨大,暗示其源区具有强烈的不均一性:部分CFB、CRB和WPB来自富集的地幔柱,仍然具有经典的OIB的特征;部分来自MORB的源区,与MORB的再循环作用有关;部分来自岛弧岩石圈之下的亏损地幔源区,以强烈亏损Nb-Ta为特征,类似岛弧玄武岩的地球化学特征。许多地区的大陆玄武岩可分为低钛和高钛两类,低钛玄武岩大多是亏损或强烈亏损的,而高钛玄武岩通常是富集型的。本文的研究表明,富集型大陆玄武岩可能来自富集的下地幔,而亏损的和强烈亏损的玄武岩可能来自具有MORB或岛弧特征的软流圈地幔。进一步指出,源区性质可能是大陆玄武岩多样性的主控因素,其次为部分熔融程度、熔融深度、结晶分离、陆壳混染以及AFC过程。     

河北张麻井矿床的矿物学研究及其对铀钼成因关系的启示

张麻井铀钼矿床是中国北方地区最大的火山岩型铀钼矿床.为探讨该矿床的铀钼成因关系,对浸染状钼(铀)矿石开展了矿物学和元素地球化学研究.除沥青铀矿外,铀石也是该矿床的一种重要铀矿物,常呈他形粒状,与胶硫钼矿、闪锌矿共生.元素面扫描结果显示,铀与钼元素的空间分布范围非常一致,表明铀和钼可能为同一期成矿作用的产物.此外,相较于...     

内蒙古东胜地区侏罗系砂岩铀矿体与煤层某些关联性

金属成矿与有机成藏的关联性是成藏成矿动力学研究的重要课题,东胜砂岩铀矿体与煤层或煤层气是何种关联尚不清楚。文中以多年勘探事实为基础,研究表明,东胜铀矿区铀矿体与煤层平面位置重叠或相近,剖面中铀矿体上下均有煤层,铀矿体与煤层垂距2～15m,两者厚度变化相互响应,铀矿体与煤层具有内在关联性。铀储层酸解烃类主要是CH4,与来自煤层的煤层气主成分一致,铀储层中从砂岩铀矿石,到铀矿化砂岩,再到无铀矿化砂岩,酸解烃类含量依次(CH4分别为569.43μL/kg、174.93μL/kg、156.12μL/kg)降低,铀矿化与煤层气内在关联明显。煤层、尤其是由它产生的煤层气是铀储层中铀矿物沉淀和成矿的重要还原剂,煤层及其厚度的变化可以作为本地区砂岩铀矿体勘探的有机质标志。     

亚热带山地民族文化与自然环境和谐发展实证研究--以云南省元阳县哈尼族梯田文化景观为例

一定的自然环境孕育了与之相适应的民族文化，而民族文化又对自然环境具有改造作用。民族文化与自然环境的相互适应是文化与环境持续存在的原因。本文通过深入到处云南南部亚热带山地地区的元阳县哈尼族地区的调查，提出和分析了哈尼文化与自然环境相互适应的结果一哈尼梯田文化景观的特征，并探讨了哈尼文化与自然环境两者梯田景观的关系，证实了哈尼梯田文化景观是哈尼文化与自然环境协调发展的结果，具有重要的理论和实际意义。     

地统计法在粒径趋势分析中的应用:以北部湾东部为例(英文)

There are 71 surface sediment samples collected from the eastern Beibu Gulf. The moment parameters (i.e. mean size, sorting and skewness) were obtained after applying grain size analysis. The geostatistical analysis was then applied to study the spatial autocorrelation for these parameters; while range, a parameter in the semivariogram that meters the scale of spatial autocorrelation, was estimated. The results indicated that the range for sorting coefficient was physically meaningful. The trend vectors calculated from grain size trend analysis model were consistent with the annual ocean circulation patterns and sediment transport rates according to previous studies. Therefore the range derived from the semivariogram of mean size can be used as the characteristic distance in the grain size trend analysis, which may remove the bias caused by the traditional way of basing on experiences or testing methods to get the characteristic distance. Hence the results from geostatistical analysis can also offer useful information for the determination of sediment sampling density in the future field work.     

河流阶地红色风化基座发育的时期与机制探讨——以粤北坪石盆地6级河流阶地为例

武江在粤北坪石盆地保留有6级河流基座阶地,是目前广东省内发现级数最多的阶地.阶地基座受后期风化作用影响,发育了深厚的红色风化基座.已有的河流阶地TL年代数据显示,本区风化基座的发育年代符合中国南方红土期的时空变化规律,但其形成机制与我国红土期相应的华南地貌风化壳有别.风化基座发育受到本区构造抬升和夏季风气候的共同影响.在我国南方红色风化壳广泛发育时期,西部地区的泥石流也出现多期活动.总体上看,泥石流发育期滞后于红土发育期,且不存在红土期内多次发育的特征,这说明夏季风气候对华南地区的影响大于西部地区.红色风化壳发育和泥石流发育共同反映出夏季风气候的加强,季风区内的水循环加快,风化侵蚀更加强烈.     

风化基座的双层夷平结构及其意义——以粤北坪石盆地第6级河流阶地为例

武江在坪石段共保留下6级基座阶地.坪石的多级基座阶地是在与粤北金鸡岭夷平面同期发育的准平原基础上,由河流的阶段性下切所形成.本区由于受以掀斜运动为特征的新构造运动的影响,阶地所在的西南岸台地区抬升速率约为0.073 m/ka,大于金鸡岭夷平面0.066 m/ka的抬升速率,致使武江在坪石段不断向东北方向摆动,沿途形成了多级基座阶地.在湿热气候条件下,尤其是在基座上覆富含有机质的河漫滩相沉积物的"储酸池"效应作用下,阶地基座发生了强烈的化学风化.该风化基座具有双层夷平结构,与我国南方覆盖型岩溶的双层夷平结构在成因上具有一致性.     

老挝人民民主共和国万象省赛宋文县爬立山铁矿地质特征及找矿方向

本文以笔者在老挝人民民主共和国万象省赛宋文县爬立山铁矿区开展铁矿产资源勘查评价项目成果为基础,对爬立山铁矿的成矿地质背景、矿床地质特征、地球物理特征、矿床成因、找矿前景等进行了比较详细的研究.结果表明,华力西期为老挝川圹—长山构造带重要的富铁矿成矿期.爬立山铁矿产于华力西期花岗闪长岩与中—上泥盆统灰岩接触带矽卡岩中.矿区矽卡岩发育,已发现的10个原生铁矿体均赋存于花岗闪长岩体与灰岩接触交代形成的矽卡岩带中.矿体形态、产状的变化受矽卡岩体控制.爬立山铁矿为产于华力西期花岗闪长岩围岩接触带中的中高温热液矽卡岩型矿床.该矿为产于花岗闪长岩围岩接触带的矽卡岩、矽卡岩化砂岩和大理岩中的大型铁矿床.在矿区外围找矿潜力巨大.矿体呈脉状、透镜状、似层状.矿体产出部位严格受矿区泥盆系中上泥盆统碳酸盐岩、钙质砂岩层位及北东、北北西向及北西向断层破碎带的控制.容矿岩石主要为中—上泥盆统矽卡岩、矽卡岩化灰岩、大理岩和钙质砂岩.矿石矿物主要以磁铁矿、赤铁矿为主,次为褐铁矿及少量黄铜矿、黄铁矿;脉石矿物主要为方解石、石英、透辉石、透闪石、石榴子石、绿泥石、绿帘石等.研究表明碳酸盐岩地层、花岗闪长岩的侵入、北西向老挝川圹—长山构造带断层的多期次活动及其后期构造作用形成的北东向断层和东西向断层是区内矽卡岩型铁矿形成的重要控制因素.在综合研究成矿地质条件和磁异常特征的基础上,总结了主要找矿标志和找矿方向,提出矿区磁异常深部及外围尚有矽卡型铁矿找矿潜力.本文的研究成果为区内找矿突破提供了新思路和新资料.为老挝川圹—长山成矿带富铁矿找矿突破奠定了基础.     

页岩储层成岩作用及其对储层脆性的影响 ——以渝西地区五峰组—龙马溪组深层页岩为例

页岩粒度细小、岩石致密、微观非均质性显著,在成岩作用改造下发育形成页岩气储层,成岩作用的研究可以为优质页岩储层发育机理提供依据.以渝西地区綦江观音桥剖面、南川泉浅1井、南川三泉剖面、大足Z-203井等代表性剖面、钻孔为例,通过X射线衍射、氩离子抛光—场发射扫描电镜、能谱、岩石薄片/光片显微观察、有机地球化学测试、力学特...     

Long-term thermal stability study of the typical embankment along the Qinghai-Tibet Railway in warm permafrost regions北大核心CSCD

Using the long-term ground temperature monitoring data of the permafrost zone along the Qinghai-Tibet Railway from 2006 to 2020,three types of typical roadbed structures were analyzed. Traditional embankment（TE）,U-shaped crushed rock embankment（UCRE）and crushed rock revetment embankment（CRRE）were included the three types of typical roadbed,which were selected to the long-term monitoring sections within the warm permafrost zones. The evolution of ground temperature field,mean annual ground temperature （MAGT）and annual maximum ground temperature（AMGT）in the depth range of 20 m under the embankment were analyzed and studied since 15 years of operation. The monitoring and analysis results show that：the growth rate of MAGT under the left and right shoulders of the TE is always higher than that of the same depth in the natural site. The MAGT under the UCRE is always lower than the natural site and always maintains a certain difference,whereas,the difference in ground temperature under the left and right shoulders is also not negligible. The MAGT of the left shoulder in the CRRE is not much different from that of the natural hole,while the MAGT of the right shoulder is always lower than that of the natural hole,and the differ in ground temperature between the left and right shoulders is smaller than that of the UCRE. The artificial permafrost table（APT）under the TE is always lower than that of in the natural site. Both the UCRE and CRRE,the APT in the left and right shoulders of them has been elevated into the embankment,and the differ of APT between the left and right shoulders is about 1. 0~1. 5 m. the differ of APT between the left and right shoulders in the CRRE is slightly lower than that of UCRE. Overall,because of the influence of thermal disturbance about engineering and climate warming,the TE in the warm permafrost zones cannot keep the thermal stability of permafrost under the embankment. Some active-cooling and reinforcement measures need to be taken. Both of the UCRE and CRRE,have a certain active-cooling effect on the permafrost under embankment,but the differ in ground temperature between the left and right shoulders still needs to be taken seriously. © 2022 Science Press (China).