Geophysical constraints on deep weathering and water storage potential in the Southern Sierra Critical Zone Observatory   总被引：1，自引：0，他引：1       下载免费PDF全文

W. Steven Holbrook  Clifford S. Riebe  Mehrez Elwaseif  Jorden L. Hayes  Kyle Basler‐Reeder  Dennis L. Harry  Armen Malazian  Anthony Dosseto  Peter C. Hartsough  Jan W. Hopmans 《地球表面变化过程与地形》2014,39(3):366-380

The conversion of bedrock to regolith marks the inception of critical zone processes, but the factors that regulate it remain poorly understood. Although the thickness and degree of weathering of regolith are widely thought to be important regulators of the development of regolith and its water‐storage potential, the functional relationships between regolith properties and the processes that generate it remain poorly documented. This is due in part to the fact that regolith is difficult to characterize by direct observations over the broad scales needed for process‐based understanding of the critical zone. Here we use seismic refraction and resistivity imaging techniques to estimate variations in regolith thickness and porosity across a forested slope and swampy meadow in the Southern Sierra Critical Zone Observatory (SSCZO). Inferred seismic velocities and electrical resistivities image a weathering zone ranging in thickness from 10 to 35 m (average = 23 m) along one intensively studied transect. The inferred weathering zone consists of roughly equal thicknesses of saprolite (P‐velocity < 2 km s^?1) and moderately weathered bedrock (P‐velocity = 2–4 km s^?1). A minimum‐porosity model assuming dry pore space shows porosities as high as 50% near the surface, decreasing to near zero at the base of weathered rock. Physical properties of saprolite samples from hand augering and push cores are consistent with our rock physics model when variations in pore saturation are taken into account. Our results indicate that saprolite is a crucial reservoir of water, potentially storing an average of 3 m³ m^?2 of water along a forested slope in the headwaters of the SSCZO. When coupled with published erosion rates from cosmogenic nuclides, our geophysical estimates of weathering zone thickness imply regolith residence times on the order of 10⁵ years. Thus, soils at the surface today may integrate weathering over glacial–interglacial fluctuations in climate. Copyright © 2013 John Wiley & Sons, Ltd.  相似文献   

渤海残留盆地油气地球物理研究综述   总被引：3，自引：2，他引：1       下载免费PDF全文

吉治平 《地球物理学进展》2005,20(4):1039-1046

本文阐述了海相残留盆地的概念,对近年来渤海海相残留盆地油藏的烃源岩、储集体、构造带及圈闭类型分布特征的研究进展进行总结,并对国内外海相盆地潜山油藏勘探历程进行概述,重点对海相残留盆地及潜山油藏综合地球物理研究现状及进展进行综述,并对未来发展趋势进行展望.  相似文献   

Geophysical investigation using resistivity and GPR methods: a case study of a lubricant oil waste disposal area in the city of Ribeirão Preto,São Paulo,Brazil     

Alexandre Lisboa Lago  Vagner Roberto Elis  Welitom Rodrigues Borges  Giovanni Chaves Penner 《Environmental Geology》2009,58(2):407-417

Geophysics has been shown to be effective in identifying areas contaminated by waste disposal, contributing to the greater efficiency of soundings programs and the installation of monitoring wells. In the study area, four trenches were constructed with a total volume of about 25,000 m³. They were almost totally filled with re-refined lubricating oil waste for approximately 25 years. No protection liners were used in the bottoms and laterals of the disposal trenches. The purpose of this work is to evaluate the potential of the resistivity and ground penetrating radar (GPR) methods in characterizing the contamination of this lubricant oil waste disposal area in Ribeirão Preto, SP, situated on the geological domain of the basalt spills of the Serra Geral Formation and the sandstones of the Botucatu Formation. Geophysical results were shown in 2D profiles. The geophysical methods used enabled the identification of geophysical anomalies, which characterized the contamination produced by the trenches filled with lubricant oil waste. Conductive anomalies (smaller than 185 Ωm) immediately below the trenches suggest the action of bacteria in the hydrocarbons, as has been observed in several sites contaminated by hydrocarbons in previously reported cases in the literature. It was also possible to define the geometry of the trenches, as evidenced by the GPR method. Direct sampling (chemical analysis of the soil and the water in the monitoring well) confirmed the contamination. In the soil analysis, low concentrations of several polycyclic aromatic hydrocarbons (PAHs) were found, mainly naphthalene and phenanthrene. In the water samples, an analysis verified contamination of the groundwater by lead (Pb). The geophysical methods used in the investigation provided an excellent tool for environmental characterization in this study of a lubricant oil waste disposal area, and could be applied in the study of similar areas.  相似文献   

Landslide Research at the British Geological Survey:Capture,Storage and Interpretation on a National and Site-Specific Scale     

Catherine PENNINGTON  Claire FOSTER  Jonathan CHAMBERS  Gareth JENKINS 《《地质学报》英文版》2009,83(5):991-999

Abstract: Landslide research at the British Geological Survey (BGS) is carried out through a number of activities, including surveying, database development and real-time monitoring of landslides. Landslide mapping across the UK has been carried out since BGS started geological mapping in 1835. Today, BGS geologists use a combination of remote sensing and ground-based investigations to survey landslides. The development of waterproof tablet computers (BGS·SIGMAmobile), with inbuilt GPS and GIS for field data capture provides an accurate and rapid mapping methodology for field surveys. Regional and national mapping of landslides is carried out in conjunction with site-specific monitoring, using terrestrial LiDAR and differential GPS technologies, which BGS has successfully developed for this application. In addition to surface monitoring, BGS is currently developing geophysical ground-imaging systems for landslide monitoring, which provide real-time information on subsurface changes prior to failure events. BGS’s mapping and monitoring activities directly feed into the BGS National Landslide Database, the most extensive source of information on landslides in Great Britain. It currently holds over 14?000 records of landslide events. By combining BGS’s corporate datasets with expert knowledge, BGS has developed a landslide hazard assessment tool, GeoSure, which provides information on the relative landslide hazard susceptibility at national scale.  相似文献   

环境与工程地球物理的新进展   总被引：16，自引：15，他引：1  

曾昭发  刘四新  刘少华 《地球物理学进展》2004,19(3):486-491

环境与工程地球物理是地球物理中的一个重要方向,并紧密与社会发展和人们生活各方面相结合,未来将倍受重视．本文在介绍2004年武汉召开的国际环境与工程地球物理学术会议(ICEEG)基础上,阐述了环境与工程地球物理领域的一些新进展和主要发展趋势．并有针对性地介绍了我国环境与工程地球物理现状。  相似文献   

矿山地震监测技术的进展及最新成果   总被引：26，自引：6，他引：20  

李世愚  和雪松  张少泉  陆其鹄  蒋秀琴  佟晓辉  李铁  管恩福  左艳  孙学会  李国基 《地球物理学进展》2004,19(4):853-859

回顾了矿山地震监测的简史,介绍了近期矿震监测技术改造情况．抚顺小孔径矿山地震台网的监测取得了比较完整的观测资料．矿震定位结果表明了矿震与开采进程的相关性．用岩石断裂力学和损伤理论的研究成果对于两类不同矿震的成因给出了最新解释．观测资料证实了矿震与瓦斯溢出的相关性．这些结果表明．在一定条件下．矿震可能成为瓦斯溢出的预警信号．由此证明,实现矿震与瓦斯浓度的联合监测是重要的,也是可行的．矿山地质灾害的综合地球物理监测对于地震成因的研究具有重要的中尺度实验意义,同时对于煤矿安全生产也将带来重要效益．  相似文献   

Successful sidetracking of a well onshore Germany by integration of 3D vertical seismic profiling technology – a case study     

S. Frehers  F. Ogliani  G. Rüth  T. Ter Burg 《Geophysical Prospecting》2012,60(6):1068-1081

The exploration for and exploitation of deep Lower Rotliegend gasfields onshore in North Germany often suffers from poor surface seismic imaging. This is owing to the depth of the reservoirs and a thick and complex Zechstein salt overburden. RWE Dea conducted a 3D vertical seismic profile (VSP) survey in a low‐performing production well after the borehole was plugged near total depth. Our main objective was to improve the seismic image of the reservoir zone in the vicinity of the well to determine a new landing point for a planned sidetrack. Because acquisition was in a densely populated and also partially environmentally protected area, there were surface restrictions concerning source deployment. Additionally, due to the complex geological setting, we conducted two 2D VSP field tests and thorough pre‐survey modelling to achieve the best results in terms of seismic imaging, environmental impact and reasonable cost. Deformation bands in the drill core suggest that the initial well was drilled close to a major fault, which was regarded as the main reason for the disappointing production rate. Therefore, we put special emphasis on fault detection in our processing and interpretation. Our interpretation approach used an enhanced structural mapping workflow that helped to design a sidetrack. When the sidetrack was drilled two years later, it ended up being one of the most productive wells in the field.  相似文献   

A methodology to estimate the maximum offset and reflection imaging radius for a 2D/3D vertical seismic profiling survey     

Min Lou  Rick Williamson  Dan Quinn 《Geophysical Prospecting》2012,60(6):1018-1023

We have developed a straightforward and ray based methodology to estimate both the maximum offset and reflection imaging radius for multi‐layered velocity models, which can be used for a 2D/3D VSP survey design. Through numerical examples, we demonstrate that the presence of a high‐velocity layer above a target zone significantly reduces the maximum offset and reflection imaging radius. Our numerical examples also show that including in a migration VSP data acquired beyond a recommended maximum offset, radically degrades the quality of the final VSP image. In addition, unlike the conventional straight‐line based approximation that often produces an incorrect large reflection imaging radius, our methodology predicts the VSP imaging radius with more accuracy than does the conventional approximation.  相似文献   

小波分析及其在我国地球物理学研究中的应用进展   总被引：4，自引：0，他引：4  

武粤  孟小红  李淑玲 《地球物理学进展》2012,27(2):750-760

小波分析在当前数学领域、物理领域和地质领域中,是一个发展迅速的分析工具,它同时具有理论上的深刻性和应用的广泛性.由于小波具有时频分析的重要特性,已经在地球物理的相关问题研究中显示其独特的作用.本文较全面的介绍了小波分析理论基础、发展历史,及其在我国地球物理学研究中的应用进展,并在此基础上对地球物理领域小波分析所存在的问题以及应用前景作了进一步的分析.  相似文献   

焦家断裂带南段深部地球物理地球化学特征与找矿方向          下载免费PDF全文

祝德成  刘汉栋  祝培刚  王巧云  张文  杨仕鹏 《山东国土资源》2017,33(12)

该文选取焦家断裂带南段的徐村院—史家地区作为研究的重点地区。通过可控源音频大地电磁测深、激电测深、钻探验证等手段,首次确定焦家断裂带自徐村院—姬家—黄家西—史家西—大尹家东一线延伸方向,将焦家断裂带沿走向向南推断了6km;认为焦家断裂带南段倾向W,倾角30°~50°,局部可达78°,断裂平面上呈S形,形态不规则;查明了焦家断裂带南段深部地球物理、地球化学特征;钻探揭露了焦家断裂带南延位置,拓展了焦家金矿带的找矿空间,提出了新的找矿方向。  相似文献