Petrogenesis of mafic and associated silicic end-member magmas for calc-alkaline mixed rocks in the Shirataka volcano,NE Japan     

Shiho Hirotani  Masao Ban  Mitsuhiro Nakagawa 《Contributions to Mineralogy and Petrology》2009,157(6):709-734

Eruptive products of the Shirataka volcano (0.9–0.7 Ma) in NE Japan are calc-alkaline andesite–dacite, and are divisible into six petrologic groups (G1–G6). Shirataka rocks possess mafic inclusions—basalt–basaltic andesite, except for G3 and G4. All rocks show mixing and mingling of the mafic and silicic end-members, with trends defined by hosts and inclusions divided into high-Cr and low-Cr types; both types coexist in G1, G2, and G5. Estimated mafic end-members are high-Cr (1120–1170°C, 48–51% SiO₂, olv ± cpx ± plg) and low-Cr type magmas (49–52% SiO₂, cpx ± plg) except for the Sr isotopic composition. In contrast, the silicic end-members of both types have similar petrologic features (790–840°C, 64–70% SiO₂, hbl ± qtz ± px + plg). High-Cr type mafic and corresponding silicic end-members have lower ⁸⁷Sr/⁸⁶Sr ratios than the low-Cr ones in each group. The trace element model calculations suggest that the low-Cr type mafic end-member magma is produced through ca. 20% fractional crystallization (olv ± cpx ± plg) from the high-Cr type one with assimilation of granitoids (r = 0.02–0.05). The silicic magmas are producible through <30% partial remelting of previously emplaced basaltic magma with assimilation of crustal components. The compositional difference between the low-K and medium-K basalts in the Shirataka volcano is mainly attributed to the different degrees of the effect of subduction derived fluid by dehydration of phlogopite. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.  相似文献   

航空物探测量中直升机起降点设置及应用          下载免费PDF全文

李健  郭亮  金久强  徐明  王志博  李冰  邓茂盛 《中国地质调查》2017,4(5):82-85

在航空物探测量飞行中,直升机以其机动灵活、出色的超低空性能以及能够沿强起伏地形飞行等特点,获得了业界认可的测量效果。但是直升机续航能力不足的弱点也成为野外飞行作业的首要问题,在测区内设置临时起降点这一方法可以很好地解决直升机续航能力不足的难题。笔者在总结直升机临时起降点设置原则基础上,利用实例说明直升机临时起降点设置方法及直升机飞行测量效率。该方法提高了野外飞行作业的效率,扩大了飞机的测量活动范围,降低了飞行作业的成本。  相似文献   

关中盆地城市群发展中几个关键基础地质问题     

董英  宋友桂  张茂省  兰敏文  付晓芬  刘慧芳  宁强强 《西北地质》2019,(2):12-26

关中盆地属于断陷盆地,地质构造复杂,活动断裂发育,地震活动频繁,城市建设中面临一系列重大基础地质问题。在搜集分析关中盆地1 000多个各类钻孔数据的基础上,对关中盆地城市群1∶5万综合地质调查中实施的主要钻井和剖面进行研究,探讨了城市群发展中面临盆地形成演化与活动断裂规避、第四系下限与关中盆地三维地质结构重建、水系演化与城市发展、历史时期古洪水事件与海绵城市建设等基础地质问题。研究表明:①关中裂陷形成于中晚白垩纪,始新世开始成湖,经过多次断陷与隆起,形成2个沉积中心,到上新世时湖泊扩展达到最大范围,盆地第四纪以来仍处于持续、缓慢的下降接受沉积过程,受秦岭持续构造隆升的影响,沉积中心由南向北迁移,这将对城市群布局产生重要影响。关中盆地城市群建设要回避断裂交汇处、端点和断层运动的枢纽部位。②建议将绿三门组划为上新统,不宜划分到第四系,三门组的形成时代是穿时的,在关中盆地第四系与地下空间规划的时候需要进行关注和纠正。③城市规划建设要遵循河湖演化的自然规律和区域地质地貌特征,千年、百年一遇的洪水水位分别高于河漫滩7m和2.2m,最大年降水量超过900mm,但季节分布不均,可作为城市防洪水和海绵城市建设的设计依据。  相似文献   

用微波炉快速测定黄土含水率最佳烘干时间的确定     

毕俊擘  张茂省  薛强 《西北地质》2019,(2):167-171

以往现场测定黄土含水率的方法主要有烘干法、酒精灼烧发、比重计法、碳酸钙气压法等。微波炉的出现给含水率测定带来新的途径。微波炉烘干是否破坏了有机质,测试数据是否有效,最佳烘干时间是多少成为不可逾越的问题。笔者以延安地区黄土及红黏土为研究对象,采用微波炉烘干和常规实验室烘箱烘干方法,对比了不同烘干时间的土样含水率,确定了土样含水率达到稳定时的烘干时间。结果表明:微波炉烘干达到10min后,其结果与烘箱烘干法一致,方法有效;微波炉设定高火力,延安马兰黄土(Qp3)烘干时间为7min,离石黄土(Qp2)烘干时间为8min,对新近系N2b-j组红粘土烘干时间为10min;与烘箱烘干法相比,波炉烘干法可现场测试,省去了送样和和长时间烘烤时间,显著提高了工作效率,可作为工程施工及地质调查现场快速测定含水率的方法。  相似文献   

基于历史相似天气评估人工增雨效果   总被引：2，自引：3，他引：2       下载免费PDF全文

耿素江  班显秀袁健 王吉宏 《气象科技》2003,31(4):231-236

文章利用辽宁省1981～1990年10年无人工增雨作业的NCEP 500hPa高度场资料以及1996年、1997年有增雨作业的500hPa资料，对10年间无增雨日及两年中增雨日要素场采用“切比雪夫一傅立叶混合多项式”展开，以寻求两个要素场的最小相关值，藉此给出两年中不同增雨天气型的个例分析及23架次日增雨效果百分率。分析结果表明，在两个要素场达到最小相关值时，一方面两个要素场形势非常相似，另一方面在增雨日播撒区的降水量，大多明显地大于该区历史上非增雨日的降雨量，增雨基本上具有正效果；然而降水一般是由多因素相互作用产生的结果，在统计时也可能出现增雨的负效果或无效果，即“多异性”；但就总体而言，该方法有效地实现了一次增雨效果的评估。  相似文献   

利用日中线法准确测定气象台站南北线          下载免费PDF全文

延雪花  刘福新  班春芳 《山西气象》2005,(3):39-39

通过地球南北极的轴线所指的方向即为正南北方向,地面上任一点的南北方向线,称为该点的真子午线(或称南北线)。气象台站南北线的准确与否影响着辐射、日照、风等仪器的正确安装,从而影响着相关气象要素的正确采集。准确测定气象台站的南北线具有重要意义。测定南北线主要有北极  相似文献   

Hydraulic and numerical study on the generation of a subaqueous landslide-induced tsunami along the coast   总被引：1，自引：0，他引：1  

Yoshinori Shigihara  Daichi Goto  Fumihiko Imamura  Yuichi Kitamura  Takayuki Matsubara  Kazuaki Takaoka  Kazuhiko Ban 《Natural Hazards》2006,39(2):159-177

By carrying out the hydraulic experiments in a one-dimensional open channel and two-dimensional basin, we clarified the process of how a landslide on a uniform slope causes the generation of a tsunami. The effect of the interactive force that occurs between the debris flow layer and the tsunami is significant in the generation of a tsunami. The continuous flow of the debris into the water makes the wave period of the tsunami short. The present experiments apply numerical simulation using the two-layer model with shear stress models on the bottom and interface, and the results are compared. The simulated debris flow shows good agreement with the measured results and ensures the rushing process into the water. We propose that the model use a Manning coefficient of 0.01 for the smooth slope and 0.015 for the rough slope, and a horizontal viscosity of 0.01 m²/s for the landslide; an interactive force of 0.2 for each layer is recommended. The dispersion effect should be included in the numerical model for the propagation from the shore.  相似文献   

气候变化国家评估报告（Ⅲ）：中国应对气候变化对策的综合评价   总被引：6，自引：0，他引：6       下载免费PDF全文

何建坤  刘滨  陈迎  徐华清  郭元  胡秀莲  张希良  李玉娥  张阿玲  陈文颖  韦志洪  段茂盛  张晓华  吕应运 《气候变化研究进展》2006,2(4):147-153

 回顾了国际社会应对气候变化的进程，对国内外的碳排放状况、中国减缓碳排放的技术潜力、中国减缓碳排放的宏观影响、全球减缓气候变化的公平性与国际合作行动等问题进行了分析与评估。提出了中国减缓气候变化的思路与对策，指出在全球应对气候变化的形势下，中国要积极适应国际政治、经济及贸易格局变动的趋势，将减缓气候变化对策纳入国家经济与社会发展战略与规划之中，促进国家经济和社会的全面、协调和可持续发展。  相似文献   

基于斜坡单元与信息量法结合的宝塔区黄土滑坡易发性评价   总被引：4，自引：0，他引：4  

薛强  张茂省  李林 《地质通报》2015,34(11):2108-2115

滑坡易发性评价对滑坡灾害的防治与管理具有重要意义。为了评价延安宝塔区黄土滑坡易发性,以斜坡为基本评价单元,选取斜坡坡度、坡高、坡向、坡形、斜坡结构类型、植被和人类工程活动7个指标作为评价因子,在Arc GIS平台下,利用信息量模型对研究区的黄土滑坡进行易发性分区评价。评价结果表明,宝塔区滑坡高易发区面积1092.39km~2,占全区面积的30.81%,主要分布于宝塔区的中部及北部地区,低易发区集中于宝塔区南部汾川河流域。以斜坡作为评价单元提高了与实际地形地貌的吻合度。应用信息量模型进行滑坡易发性评价具有较高的预测精度,已有滑坡点落在很高易发区和高易发区中的比例为95.7%,较真实地反映了客观实际。  相似文献   

Collaborative validation of GlobeLand30:Methodology and practices     

Jun Chen  Lijun Chen  Fei Chen  Yifang Ban  Songnian Li  Gang Han  Xiaohua Tong  Chuang Liu  Vanya Stamenova  Stefan Stamenov 《地球空间信息科学学报》2021,24(1):134-144

30-m Global Land Cover(GLC)data products permit the detection of land cover changes at the scale of most human land activities,and are therefore used as fundamental information for sustainable development,environmental change studies,and many other societal benefit areas.In the past few years,increasing efforts have been devoted to the accuracy assessment of GlobeLand30 and other finer-resolution GLC data products.However,most of them were conducted either within a limited percentage of map sheets selected from a global scale or in some individual countries(areas),and there are still many areas where the uncertainty of 30-m resolution GLC data products remains to be validated and documented.In order to promote a comprehensive and collaborative validation of 30-m GLC data products,the GEO Global Land Cover Community Activity had organized a project from 2015 to 2017,to examine and explore its major problems,including the lack of international agreed validation guidelines and on-line tools for facilitating collaborative validation activities.With the joint effort of experts and users from 30 GEO member countries or participating organizations,a technical specification for 30-m GLC validation was developed based on the findings and experiences.An on-line validation tool,GLCVal,was developed by integrating land cover validation procedures with the service computing technologies.About 20 countries(regions)have completed the accuracy assess-ment of GlobeLand30 for their territories with the guidance of the technical specification and the support of GLCVal.  相似文献