Petrogenesis of Early Cretaceous hornblende gabbro in Khanka Massif: evidence from geochronology and geochemistry     

WEI Chunxia  WEI Xu  ZHU Weigang  XU Wenliang 《世界地质(英文版)》2018,(3)

The authors report zircon U-Pb geochronological,whole-rock geochemical and zircon Lu-Hf isotope data for the hornblende gabbro within the Khanka Massif,with the aim of constraining its formation time and petrogenesis. The zircon U-Pb dating shows that ~(206)Pb/~(238)Pb ages of zircons from the hornblende gabbro range from 120 to 129 Ma,yielding a weighted mean age of 123 ± 2 Ma,i. e.,the Early Cretaceous. The hornblende gabbro has SiO_2 of 44. 77%--46. 58% and belongs to the tholeiitic series on FeO~t/MgO-SiO_2 diagram. It displays a right-inclined REE pattern with( La/Yb)_N ratios of 3. 44 to 4. 42. The trace element spidergram shows that they are enriched in large ion lithophile elements( LILE) such as Rb,Th,U,K and Pb,and depleted in high field strength elements( HFSE) such as Nb,Ta,Ti and P,indicating an affinity to arc igneous rocks.The ε_(Hf)( t) values of zircons vary from -2. 6 to + 3. 9 and Hf model ages( T_(DM1)) range from 622 to 883 Ma.These geochemical characteristics indicate that primary magma of the hornblende gabbro could be derived from partial melting of young mantle material accreted during the Neoproterozoic. Combined with the Early Cretaceous igneous rock assemblages in NE Asia. It is concluded that the hornblende gabbro formed in an active continental margin related to the westward subduction of the Paleo-Pacific Plate beneath the Khanka Massif.  相似文献   

An algorithm to resolve γ-rays from charged cosmic rays with DAMPE     

Zun-Lei Xu  Kai-Kai Duan  Zhao-Qiang Shen  Shi-Jun Lei  Tie-Kuang Dong  Fabio Gargano  Simone Garrappa  Dong-Ya Guo  Wei Jiang  Xiang Li  Yun-Feng Liang  Mario Nicola Mazziotta  Maria Fernanda Munoz Salinas  Meng Su  Valerio Vagelli  Qiang Yuan  Chuan Yue  Jing-Jing Zang  Ya-Peng Zhang  Yun-Long Zhang  Stephan Zimmer 《天文和天体物理学研究(英文版)》2018,(3)

The DArk Matter Particle Explorer(DAMPE),also known as Wukong in China,which was launched on 2015 December 17,is a new high energy cosmic ray and γ-ray satellite-borne observatory.One of the main scientific goals of DAMPE is to observe Ge V-Te V high energy γ-rays with accurate energy,angular and time resolution,to indirectly search for dark matter particles and for the study of high energy astrophysics. Due to the comparatively higher fluxes of charged cosmic rays with respect to γ-rays,it is challenging to identify γ-rays with sufficiently high efficiency,minimizing the amount of charged cosmic ray contamination. In this work we present a method to identify γ-rays in DAMPE data based on Monte Carlo simulations,using the powerful electromagnetic/hadronic shower discrimination provided by the calorimeter and the veto detection of charged particles provided by the plastic scintillation detector. Monte Carlo simulations show that after this selection the number of electrons and protons that contaminate the selected γ-ray events at～10 Ge V amounts to less than 1% of the selected sample.Finally,we use flight data to verify the effectiveness of the method by highlighting known γ-ray sources in the sky and by reconstructing preliminary light curves of the Geminga pulsar.  相似文献   

浙江朱家尖岛东沙海滩对热带风暴“娜基莉”的响应及风暴后的恢复   总被引：1，自引：1，他引：0  

郭俊丽  时连强  童宵岭  郑禹君  徐岱璐 《海洋学报》2018,40(9):137-147

海滩对风暴的响应及风暴后海滩的恢复过程一直以来都是国内外海滩研究的热点。本文通过对浙江舟山市朱家尖岛东沙海滩地形地貌的现场调查，对比分析了热带风暴"娜基莉"影响下东沙海滩剖面的蚀积变化，探讨了海滩在热带风暴发生后的恢复情况。结果表明，在"娜基莉"影响期间，因风暴浪为向岸浪，东沙海滩几乎遭受全线侵蚀，12个剖面单宽侵蚀总量为73.46 m3/m，其中海滩直线段较两个遮蔽段侵蚀显著。由于海滩在风暴前进方向的左侧，且"娜基莉"距东沙较远，使得东沙海滩普遍侵蚀但强度较小。东沙海滩在热带风暴后的恢复过程中，不同部位的地貌调整和冲淤变化不同，下岬角遮蔽段基本趋于稳定，直线段和上岬角遮蔽段在恢复过程中因受海滩季节性调整的影响呈现持续侵蚀。  相似文献   

城市地质学基础理论探讨     

林良俊  马震  郭旭  Zhenya Zhang  李亚民 《中国地质》2020,47(6):1668-1676

城市地质有近百年的研究历史，学科研究取得了很大的进展，但是总体上看，学科性质存在较多的争论，城市地质学基础理论难于满足现代城市管理的需求，无法为城市高质量发展提供系统完整的地学解决方案。本文系统梳理了国内外城市地质的发展历程和研究进展，进一步明确了城市地质学的学科性质，运用系统理论提出城市地质系统的概念，并基于这一概念，清晰地界定了城市地质学的研究对象，阐述了现代城市地质学的研究内容和技术框架，为今后形成完善的城市地质学理论体系提供研究基础。  相似文献   

末次冰消期（1.9万年）以来冲绳海槽中部黏土矿物来源及其环境响应          下载免费PDF全文

田旭  胡邦琦  王飞飞  黄威  丁雪  宋维宇  徐方建 《中国地质》2020,47(5):1501-1511

基于采自冲绳海槽中部的CS2站柱状沉积物黏土矿物和AMS¹⁴C年代分析，探讨了末次冰消期以来冲绳海槽中部黏土矿物的物质来源及其环境指示意义。结果显示，CS2站黏土矿物以伊利石为主，其次为绿泥石，高岭石和蒙脱石含量较少。根据黏土矿物分布趋势变化，CS2站柱状沉积物可划分为3个阶段：阶段（I 19~12 ka BP）和阶段Ⅱ （12~8 ka BP）期间沉积物主要来源于长江，台湾和黄河物质也有一定影响，其物质来源主要受海平面升降的控制；阶段Ⅲ（8~0 ka BP）主要来源于长江和台湾，黄河贡献有限，主要受黑潮演化的影响。CS2站（蒙脱石+高岭石） （/伊利石+绿泥石）比值可以作为东亚季风演化的矿物学指标，指标变化显示出东亚冬季风强度相对夏季风的强度在16.4~14.8 ka BP和12.8~11.6 ka BP期间有两次显著的加强，指示当时气候相对寒冷干燥，结果可以与格陵兰冰心δ¹⁸O和三宝洞δ¹⁸O记录等很好对比。  相似文献   

中国陆相油页岩含油率与总有机碳的响应机理     

贾建亮  刘招君  孟庆涛  孙平昌  徐进军  柳蓉  白悦悦 《吉林大学学报(地球科学版)》2020,50(2):368-377

为了建立稳定可靠的利用油页岩总有机碳预测含油率的模型，揭示中国陆相不同成因类型油页岩含油率与总有机碳的内在关系极其重要。通过不同类型盆地油页岩钻井取心测试的关键参数，结合沉积学、有机地球化学、热模拟等学科技术，探讨油页岩含油率与总有机碳的响应机理。结果表明：不同盆地类型与沉积背景下发育的油页岩含油率与总有机碳质量分数均呈现良好的正相关性（R²=0.81~0.97）；中国陆相油页岩的成因类型进一步划分为5种类型，制约着含油率与总有机碳的内在关系；油页岩的升温加热模拟呈现3个失重阶段（温度<150、300~550、600~750℃），明确了含油率与总有机碳参数的物理意义；相同类型盆地与沉积背景下形成的油页岩具有相近的母质生源组合，从而具有大致相当的再生烃效率。中国陆相油页岩成因类型的细划、含油率与总有机碳物理意义的明确、油页岩再生烃能力的分析，有助于理解中国陆相油页岩含油率与总有机碳的内在响应关系。  相似文献   

中国与“一带一路”沿线国家贸易及其影响因素     

许阳贵  刘云刚 《热带地理》2019,39(6):855-868

利用拓展贸易引力模型,借助Eviews等工具分析了影响中国与“一带一路”沿线国家贸易规模的因素,以及中国对外直接投资的滞后性对双边贸易的影响。结果表明：1）中国与“一带一路”沿线国家贸易规模受到经济发展水平、市场规模、政治制度、贸易畅通性、便利性、中国对外直接投资、民间文化交流紧密度的影响;2）中国对外直接投资对于带动中国与“一带一路”沿线国家间的贸易规模具有正向作用,但其效应具有一定滞后性;3）中国对外直接投资对于带动中国与不同“一带一路”沿线国家贸易规模的引力大小不同,可分为投资带动力巨大型、投资带动型、投资一般型、投资带动力不足型4种类型,中国与东南亚、西亚和撒哈拉以南的非洲国家贸易规模受中国对外直接投资带动作用较强。  相似文献   

Effects of current climate,paleo-climate,and habitat heterogeneity in determining biogeographical patterns of evergreen broad-leaved woody plants in China   总被引：1，自引：1，他引：0  

Xu  Yue  Shen  Zehao  Ying  Lingxiao  Zang  Runguo  Jiang  Youxu 《地理学报(英文版)》2019,29(7):1142-1158

Journal of Geographical Sciences - Understanding biogeographic patterns and the mechanisms underlying them has been a main issue in macroecology and biogeography, and has implications for...  相似文献   

Primary investigation of statistical correlation between changes in ice volume and area of glaciers     

PuYu Wang  ZhongQin Li  ChunHai Xu  Ping Zhou  WenBin Wang  Shuang Jin  HongLiang Li 《寒旱区科学》2019,11(1):41-49

This study makes an attempt to investigate through statistical analysis the correlation between changes in ice volume and area of glaciers. Using data from nine sample glaciers in the Tian Shan, the results show that a linear relation exists between changes in ice volume and area, with a correlation coefficient of 0.700. However, the accuracy estimation is difficult due to the limited number of samples. The correlation was not improved after adding eleven glacier samples in other mountains. Two reference glaciers are then analyzed in more detail. The linear correlation coefficient is higher than 0.800 when using the observed changes in ice volume and area during different periods on Urumqi Glacier No. 1, which suggests that the linear relation is valid for one glacier for different periods if its shape does not change noticeably and also for other glaciers of the same shape during the same period. The relation between changes in ice volume and area of Qingbingtan Glacier No. 72 is different during different periods due to change in the shape of the glacier tongue and the influence of the debris cover. Moreover, errors in glacier-change monitoring and-volume estimation have an important influence on the correlation results. Therefore, further study needs to focus not only on the distinction between glacier types and between different periods but also on the accuracy of volume estimation.  相似文献   

乡村农户旅游适应效果、模式及其影响因素——以西安市和咸阳市17个案例村为例     

何旭  杨海娟  王晓雅 《地理研究》2019,38(9):2330-2345

乡村旅游地面临人地交互作用的剧烈变迁,内部要素适应社会-生态系统变化,趋利避害降低脆弱性具有重要现实意义。本文重新界定基于恢复力和脆弱性的农户适应性理论内涵,构建旅游开发适应力指标体系,以西安市和咸阳市17个不同类型的城郊型乡村旅游地为例,评价和分析农户旅游适应效果与空间差异规律,探讨和归纳适应行为与对策模式,建立BP神经网络辨别和揭示适应性影响因素与重要性关系。研究表明：① 西安市和咸阳市农户适应旅游开发综合效果呈现中等偏下水平的偏态分布趋势,分别处于旅游地生命周期快速发展阶段和探索起步阶段。② 乡村旅游地农户适应效果形成“圈层辐射、两翼包络、外围联动”的县域尺度空间分布格局;村域尺度圈层分化现象显著。③ 经营模式划分的旅游乡村农户适应效果股份制模式>“公司+农户”模式>“政府+公司+农户”模式>个体农庄模式>“农户+农户”模式;常年外出务工和农家乐经营是农户主要适应行为选择,季节性务工、本地上班以及农业生产是辅助适应行为选择,且适应行为组合方式表现为旅游专营型、旅游主导型、均衡兼营型、务工主导型和务农主导型五种适应对策模式。④ 旅游发展机会认知、技能培训机会、社会联结度、劳动力总量、政策知晓度、旅游就业人数、收入来源种类、生活主要能源、受教育程度、公共服务设施是农户主要旅游适应性影响因素。据此,提出后续社会-生态整合研究亟需突破方向和适应旅游开发的政策路径。  相似文献