黔东南地区新元古代下江群的地层年代及其地质意义   总被引：3，自引：0，他引：3       下载免费PDF全文

覃永军  杜远生  牟军  卢定彪  龙建喜  王安华  张厚松  曾昌兴 《地球科学》2015,40(7):1107-1120

黔东南地区下江群是分布在江南造山带西段的一套前寒武纪浅变质陆源碎屑岩夹火山碎屑岩组合, 其地层时代归属与划分特别是区域地层对比一直未能得到很好解决.在对该区前寒武纪地层广泛而详细的剖面测制和地质调查基础上, 运用LA-ICP-MS技术, 对地层中沉凝灰岩、含凝灰质碎屑岩和碎屑岩进行锆石U-Pb年代学测试, 获得一批高精度的年龄.四堡群河村组顶部的碎屑岩和下江群乌叶组第1段顶部的含凝灰质碎屑岩、清水江组底部与中部的沉凝灰岩、平略组中上部的含凝灰质碎屑岩、隆里组中下部的碎屑岩等样品中锆石U-Pb最小年龄组的加权平均年龄分别为819.8±6.4Ma和779.5±4.7Ma、764.0±6.3Ma与(756.8±7.6Ma、756.0±13.0Ma)、733.9±8.8Ma及725.0±10.0Ma.这些数据将四堡群和下江群的时代限制为新元古代.结合研究区隆里组与长安组整合接触关系和全球低纬度南华系冰期起始年龄(717.4Ma)的地质事实, 将下江群沉积时限约束在815~717Ma之间.根据区域岩浆事件进一步约束了下江群各组段的地层时限, 并开展江南造山带下江群及其相当层位的地层划分与对比, 认为新元古代岩浆作用制约着黔东南下江群盆地的演化.   相似文献   

酸雨对桂林枯水期岩溶地下水δ13C_DIC及碳汇效应的影响   总被引：1，自引：0，他引：1       下载免费PDF全文

黄奇波  覃小群  刘朋雨  唐萍萍 《地球科学》2015,40(7):1237-1247

定量评价硫酸对岩溶碳汇效应的影响有助于提高岩石风化碳汇通量估算精度, 对当前全球气候变化研究意义重大.选取受酸雨影响的桂林岩溶区为研究对象, 在枯水期对研究区14个岩溶大泉和15条地下河水化学成分和碳同位素进行了测试分析, 结果表明: 岩溶大泉和地下河中阳离子以Mg2+和Ca2+为主, 阴离子以HCO₃-为主, 分别占阳离子和阴离子组成的90%以上, SO₄2-含量较低, 其含量范围为0.004~0.213mmol/L; 所占阴离子组成比例为0.12%~6.11%;δ13C_DIC、[Ca2++Mg2+]/[HCO₃-]更偏向于碳酸溶解端元, 离硫酸溶解端元距离远, 证实硫酸参与碳酸盐岩的溶解对地下水无机碳(dissolved inorganic carbon, 简称DIC)及δ13C_DIC的影响有限; 与Sr2+/Ca2+值一样, δ13C_DIC主要受径流条件控制, 其大小可以反映地下水径流条件的强弱.利用化学计量关系计算出由硫酸溶蚀碳酸盐岩的平均比例为22.64%, 产生的DIC(HCO₃-_H2SO4)占总DIC的平均比例为13.04%, 碳酸产生的DIC(HCO₃-_H2CO3)占地下水总DIC的比例为86.96%, 其中来源于土壤大气中的HCO₃-比例为43.48%.因此, 扣除硫酸对地下水中DIC的贡献后, 岩溶碳汇效应将减少13.04%.   相似文献   

塔北西部一间房组碳酸盐岩礁滩体同生期暴露溶蚀作用模式          下载免费PDF全文

赵学钦  杨海军马 青周成刚  孙崇浩蔡 泉 孙仕勇 《中国地质》2015,(6):1811-1811

在详细的钻井资料和岩心的宏观及微观特征研究的基础上,通过对塔北隆起西部奥陶系中统一间房组礁滩体沉积相特征及展布规律的分析,结合礁滩体储层同生期溶蚀作用特征研究,按照古沉积地貌单元结合岩相的方法建立了一间房组礁滩体同生期溶蚀作用模式。研究认为一间房组开阔台地相包括台内滩、滩间海和台内点礁3个亚相,沉积相平面分布稳定;一间房组的同生期暴露溶蚀作用明显,普遍反映出滩体的间歇性暴露的特征:生物钻孔和溶蚀孔洞内充填礁滩体暴露形成的古土壤泥;发育潮间带的化石碎片堆积和软体生物活动遗迹;岩心观察和成像测井可以识别出渗流-潜流带溶蚀作用旋回。按照礁滩相沉积地貌结合岩相的模式,将一间房组开阔台地的浅滩和点礁沉积划分出潮上长期暴露滩、潮间间歇暴露滩、潮下高能滩、瓶筐石障积礁、潮汐水道等地貌单元。  相似文献   

锰钾矿光催化降解苯酚及其影响因素研究     

于力茜  张嵚  程晓迪  吕红晓  赖发英 《岩石矿物学杂志》2015,34(2):251-256

利用回流法合成隧道结构的锰钾矿,并研究其光化学降解苯酚的效果及影响因素。分别采用X射线衍射、原子吸收光谱、扫描电镜、透射电镜和BET氮气吸附法对锰钾矿的晶体结构(包括晶型、晶胞参数和结晶度)、化学组成、微观形貌和比表面积进行了表征。研究表明,非光照时锰钾矿对苯酚的降解效果较差,光照能显著促进锰钾矿对苯酚的降解;光照条件下,p H值减小能显著促进锰钾矿对苯酚的降解;锰钾矿用量增加至1.00 g/L时能显著促进锰钾矿降解苯酚,但继续增加矿物用量却显著降低苯酚降解率;非光照条件下,p H值减小和矿物用量增加不能显著促进锰钾矿降解苯酚。  相似文献   

Identification and control of spontaneous combustion of coal pillars: a case study in the Qianyingzi Mine,China   总被引：1，自引：1，他引：0  

Yi Lu  Botao Qin 《Natural Hazards》2015,75(3):2683-2697

  相似文献   

An Review of International Climate Change Conference and Analysis on Recent Hot Issues     

Zeng Jingjing  Qu Jiansheng  Pei Huijuan  Dong Liping  Liao Qin  Liu Yanfei  Zhang Zhiqiang 《地球科学进展》2015,30(11):1210-1217

The international climate change negotiation has been carried out over 20 years. The issue of climate change has shifted from a scientific question into a complex political matter which is related to the sustainable development of mankind. Based on the overview of major processes and stages of international climate conferences, this paper analyzed the key measures that major countries have taken to address climate change, as well as the primary tasks of Paris climate conference and recent international actions. The recent international climate policy issues were also analyzed in order to provide suggestions for China’s activel participation in the development of a new round of international climate change system.  相似文献   

InSAR滑坡探测技术研究——以金沙江乌东德水电站段为例     

康亚  赵超英  张勤  刘晓杰 《大地测量与地球动力学》2018,38(10):1053-1057

采用3类InSAR产品和DEM数据开展金沙江流域乌东德水电站段的潜在滑坡探测，成功识别出多处已知和未知的滑坡点，并探测出滑坡体的形态及稳定性，提供了一种高效的大范围滑坡探测技术。同时采用小基线集InSAR技术对金坪子滑坡进行监测，不仅获得该滑坡的空间分区特征，也获取重点滑坡区的时间序列结果，并且与地面监测结果比较，精度达1.8 cm。展示了不同InSAR技术在不同尺度滑坡调查与监测中的应用特点。  相似文献   

Energy partitioning over a semi‐arid shrubland in northern China          下载免费PDF全文

X. Jia  T. S. Zha  J. N. Gong  B. Wu  Y. Q. Zhang  S. G. Qin  G. P. Chen  W. Feng  S. Kellomäki  H. Peltola 《水文研究》2016,30(6):972-985

During the last decade, the widely distributed shrublands in northern China have shown significant signs of recovery from desertification, the result of widespread conservation practices. However, to support the current efforts in conservation, more knowledge is needed on surface energy partitioning and its biophysical controls. Using eddy‐covariance measurements made over a semi‐arid shrubland in northwest China in 2012, we examined how surface energy‐balance components vary on diurnal and seasonal scales, and how biophysical factors control bulk surface parameters and energy exchange. Sensible heat flux (H) exceeded latent heat flux (λE) during most of the year, resulting in an annual Bowen ratio (β, i.e. H/λE) of 2.0. λE exceeded H only in mid‐summer when frequent rainfall co‐occurred with the seasonal peak in leaf area index (LAI). Evapotranspiration reached a daily maximum of 3.3 mm day^?1, and summed to 283 mm yr^?1. The evaporative fraction (EF, i.e. λE/R_n), Priestley–Taylor coefficient (α), surface conductance (g_s) and decoupling coefficient (Ω) were all positively correlated with soil water content (SWC) and LAI. The direct enhancement of λE by high vapour pressure deficit (VPD) was buffered by a concurrent suppression of g_s. The g_s played a direct role in controlling EF and α by mediating the effects of LAI, SWC and VPD. Our results highlight the importance of adaptive plant responses to water scarcity in regulating ecosystem energy partitioning, and suggest an important role for revegetation in the reversal of desertification in semi‐arid areas. Copyright © 2015 John Wiley & Sons, Ltd.  相似文献   

Pollen-based Holocene quantitative temperature reconstruction on the eastern Tibetan Plateau using a comprehensive method framework     

Liang  Chen  Zhao  Yan  Qin  Feng  Zheng  Zhuo  Xiao  Xiayun  Ma  Chunmei  Li  Huan  Zhao  Wenwei 《中国科学:地球科学(英文版)》2020,63(8):1144-1160

Quantitative climate reconstruction on long timescales can provide important insights for understanding the climate variability and providing valuable data for simulations. Unfortunately, the credibility of some attempts was hampered by incomplete reconstruction procedures. We here establish a comprehensive framework resting on high-quality Chinese modern pollen database, including modern pollen data screening, calibration set selection, major climate factor analysis, appropriate model selection, strict statistical assessment of results and ecological interpretation. The application of this framework to three high-resolution pollen records from the eastern Tibetan Plateau allows accurate quantitative inferences of Holocene temperature changes, which is the major control of regional vegetation. The results show that the mean warmest month temperature(MTwa)during the early Holocene was ca. 10.4℃ and reached the highest value at 8.5–6 ka BP(ca. 11℃). The early and mid-Holocene(11–5 ka BP) warmth was followed by 1.2℃ temperature decrease, culminating in the coolest temperatures of the Holocene during the Neoglacial cooling. Superimposing on the general cooling trend, MTwareveals a significant 500-yr periodicity with varying intensities through time, showing that warm(cold) intervals are in phase with solar maxima(minima) periods. This spectral similarity indicates a possible connection of multi-century scale climate fluctuations with solar forcing.  相似文献   

中国旅游城市生态安全系统评估与类型划分研究 ——基于节点权重约束网络DEA模型   总被引：2，自引：2，他引：0  

秦晓楠  程钰 《地理科学》2019,39(1):156-163

采用 DPSIR概念模型作为旅游生态安全系统的基本形态,引入网络 DEA模型测度系统运行效率,从“投入-产出”的研究视角探究旅游生态安全系统内部作用机理。采用结构方程模型对网络 DEA模型的结构及权重加以限制,构建具有节点权重约束的网络 DEA评价模型,对主要旅游城市生态安全系统实例进行实证研究。研究结果认为：将生态安全系统分为自然运行阶段、管理反馈阶段2阶段进行效率评价,加权综合得出各旅游城市生态安全系统的综合评价值,以此为依据将样本城市划分为按系统效率的评价结果将其分划为绿色发展型、稳步发展型、高效发展型、双向提升型和管理能力缺失型,针对各类型旅游城生态安全系统特点提出改善其生态安全系统状况的建议。  相似文献