中国黄土与红色粘土记录的地磁极性界限及地质意义   总被引：13，自引：0，他引：13       下载免费PDF全文

岳乐平 《地球物理学报》1995,38(3):311-320

本文报道由蓝田、陕县、洛川、西峰、平凉、兰州及靖远等剖面获得的古地磁研究结果．主要结论为：１．中国黄土剖面记录了Ｂｒｕｎｈｅｓ正极性带与Ｍａｔｕｙａｍａ负极性带，Ｂｒｕｎｈｅｓ／Ｍａｔｕｙａｍａ极性转换过程位于第８层黄土（Ｌ８）．在段家坡黄土剖面该转换过程对应的地层厚度为０．３７５ｍ，持续时间约６０００ａ．转换过程由３次极性变化构成，每次经历的时间约为４００ａ．２．Ｊａｒａｍｉｌｌｏ正极性亚带（Ｊ）位于标志层Ｌ９至Ｌ１５之间，大约Ｓ１０－Ｓ１３位置．３．Ｏｌｄｕｖａｉ正极性亚带（Ｏ）对应的地层为Ｓ２７－Ｓ３３４．Ｒｅｕｎｉｏｎ正极性亚带（Ｒ）由两部分组成，在蓝田段家坡黄土剖面分别位于Ｌ３６和Ｓ３８５．Ｍａｔｕｙａｍａ负极性带与Ｇａｕｓｓ正极性带界限（Ｍ／Ｇａ）位于黄土和红色粘土交界处，中国黄土的底界年龄为２．４８Ｍａ左右．黄土与红色粘土为整合接触关系．６．黄土下伏的红色粘土记录了Ｇａｕｓｓ正极性带，Ｇｉｌｂｅｒｔ负极性带和古地磁年表编号５（Ｅｐｏｃｈ５）．  相似文献   

EUTROPHICATION AND RED TIDES AS CONSEQUENCES OF ECONOMIC DEVELOPMENT   总被引：4，自引：0，他引：4  

Zhao-Yin WANG  Yongsheng WU  and Guangqian WANG Prof.  Dept. of Hydraulic Engineering  Tsinghua University & International Research  Training Center on Erosion  Sedimentation  Beijing  China  Email: zywang@tsinghua.edu.cn or zywang@sun 《国际泥沙研究》2001,16(4)

1 mTRoorcnoxThe EnvirDment AgenCy of UK (l997) defins eUtIDPhication as "the enrichInnt of waters byinorgedc plant nUtrientS that result in the simulation of an mp Of syInPtOInati changes. These includethe inCrased PrOduCtiOn Of aigae or othe aquatic PlantS, affeChng the quallty of the water and distUIbingthe balance Of orpedsms Present within it. Such changes Inay be undesirable and intetw with wateuses." Sndth et al. (l999) indicated tha eopation of waters is mainly caused by h…  相似文献   

Environmental impact on construction limestone at humid regions with an emphasis on salt weathering,Al-hambra islamic archaeological site,Granada City,Spain: case study     

G. M. E. Kamh 《Environmental Geology》2007,52(8):1539-1547

Al-hambra is an immense and valuable archaeological site in Spain built on Sabika hill with red brick and natural sandy limestone. It exhibits weathering features indicating salt weathering process. The main aim of this study is to examine weathering processes and intensity acting on Al-hambra. Rock petrography and mineralogical composition have been examined using thin sections, scanning electron microscope, X-ray diffraction and X-ray fluorescence; limits of rock’s physical parameters using ultrasonic waves and mercury porosimeter; rock salt content through hydrochemical analysis. Salts attacking this structure are mainly from wet deposition of air pollutants on the long term chemical alteration of rock’s carbonate content to its equivalent salts. The salts’ concentration limit within the examined rock samples is considerably low but it is effective on the long run through hydration of sulphate salts and/or crystallization of chloride salts. Rock texture type and its silica as well as clay content reduces its resistance to internal stresses by salts as well as wetting and drying cycles at such humid area. The recession in limits of physical parameters examined for deep seated and weathered limestone samples quantitatively reflects weathering intensity on Al-hambra.  相似文献   

Comment on “Is there a paleolimnological explanation for ‘walking on water’ in the Sea of Galilee?”     

Matthias Prange  Helge Arz  Frank Lamy 《Journal of Paleolimnology》2007,38(4):589-593

In a recent paper, Nof et al. (J Paleolimnol 35:417–439, 2006) suggest a physical mechanism which could account for the formation of ice on Lake Kinneret (Sea of Galilee) in northern Israel. Based on the sea surface temperature record of sediment cores from the Mediterranean Sea the authors argue that centennial-scale cold events had the potential to trigger local ‘springs ice’ formation on the lake in the past. Here, we demonstrate that a closer inspection of the paleoceanographic record in combination with correlation and regression analyses of meteorological data provides no evidence for such cold events in the lake region during the last 10,000 years. Thus, the formation of ‘springs ice’ on Lake Kinneret was unlikely at least since the beginning of the Neolithic.  相似文献   

沁水煤田霍东地区山西组主要煤层对比     

刘仙平  张学彦 《中国煤田地质》2002,14(3):17-18

运用标志层、层间距、物性特征、煤层本身特征等方法，对霍东地区沁安矿区和沁源矿区山西组1号、2号、3号煤层进行对比，认为沁安矿区未沉积3号煤层，该矿区现有的两个煤与沁源矿区的1号、2号煤层可比，而不是2号、3号煤层，其中既有定性又有定量，较成功的解决了南北两大矿区山本组主要可采煤层间的对比问题。  相似文献   

陶器资源——江西红土岩开发   总被引：4，自引：0，他引：4  

王平  彭人勇  周萍华 《华东地质学院学报》2001,24(2):131-134

依据江西红土岩物质组成特征及与宜兴紫砂土的相似性，对江西红土岩进行了较系统的陶器实验与研究。江西红土岩系的化学成分、矿物成分及工艺特征适合陶器要求。按其分布规律和物质组成特征可分成两类：酸性红土岩和碱性红土岩。在详细分析两类岩系工艺性质的基础上，对江西红土岩这一陶器资源进行了产品开发。  相似文献   

Three‐dimensional flow structure around small‐scale bedforms in a simulated gravel‐bed environment     

Mark Lawless  Andr Robert 《地球表面变化过程与地形》2001,26(5):507-522

Pebble clusters are common small‐scale morphological features in gravel‐bed rivers, occupying as much as 10 per cent of the bed surface. Important links exist between the presence of pebble clusters and the development of flow structures. These links are poorly understood at the three‐dimensional level. Particularly neglected has been the effect of clusters on the lateral flow characteristics. A laboratory study was conducted using a hydraulic flume, within which simulated pebble clusters were superimposed onto a plane bed of gravel material. High‐resolution three‐dimensional flow data were collected above the bed at two different flow depths using an acoustic Doppler velocimeter. The results present evidence of the importance of lateral flow in the development of turbulent flow structure. Narrow regions of high lateral and downstream turbulence intensity exist to both sides of clusters and in a three‐dimensional separation zone in their lee. This may indicate the presence of horseshoe‐type vortical structures analogous to those identified in less hydraulically rough environments. However, it is likely that these structures are more complicated given the mutual interference of the surrounding medium. The lateral flow was also identified as a key component in the upwelling identified by other authors in the lee of pebble clusters. The results of the vertical flow analysis confirm the hypothesis that six regions with distinct vertical flow characteristics exist above clusters: flow acceleration up the stoss‐side of the cluster; recirculation behind the cluster in the wake region; vortex shedding from the pebble crest and shear layer; flow reattachment downstream of the cluster; upwelling of flow downstream of the point of reattachment; and recovery of flow. Copyright © 2001 John Wiley & Sons, Ltd.  相似文献   

陆相红层盆地1:5万区调中的遥感应用研究   总被引：3，自引：0，他引：3  

刘登忠 《国土资源遥感》1996,7(2):45-50

本文采用遥感地质方法,对陆相红层盆地的沉积岩相、沉积体系界面、盆地充填序列、岩相变化以及地层格架影像特征进行了识别研究,取得了较好效果,为遥感在红层盆地1:5万区调中的应用,开辟了新思路。  相似文献   

青藏高原东北部古喀斯特过程与环境   总被引：6，自引：0，他引：6  

崔之久  陈怀录 《地理学报》1996,51(5):408-417,T001

本文介绍了青藏高原东北部地区的古喀斯特现象，并对相关沉积进行了化学成、粘土矿物的Ｘ－射线衍射以及石英砂表面结构等气候代用指标的分析。分析结果一致，指示了温暖湿润的亚热带气候条件。重结晶方解石的裂变径迹测年结果表明，该地区古喀斯特发育于中中新世。  相似文献   

红层（盆）与金矿化关系的探讨     

连立祥 《铀矿地质》1995,11(5):284-290

红层（盆）内外存在着工业金矿化现象，与红层（盆）有关的金矿化包括：次火山岩型、卡林型、穆龙套型、不整合脉型、风化壳型、热泉型以及砂金等众多类型。它们的形成过程及分布与红层（盆）关系密切。本文总结了与红层（盆）有关金矿化的成矿模式及找矿方向。  相似文献