Three-dimensional Geological Mapping Research Articles

Geomorphology, Three-Dimensional Geology, and Seismologic Hazards of the New Madrid Seismic Zone in Dyer County, Tennessee

ABSTRACTGeomorphic and three-dimensional geologic mapping reveals two major fault systems of the seismically active Reelfoot rift pass beneath Dyer County in northwestern Tennessee, the Reelfoot South fault, and the east-bounding faults of the Reelfoot rift. The Dyer County mapping also indicates that the two principal Reelfoot South fault hanging wall structures, the Lake County uplift and Tiptonville dome, pass beneath the county. Quaternary displacement was identified on southeastern Reelfoot rift margin faults in Dyer County, thus indicating that this rift margin has been active during the Quaternary from adjacent Obion County through Dyer County to Lauderdale County, Tennessee, for a distance of at least 60 km. The three-dimensional geologic mapping also provides stratigraphic thicknesses of surface sediment and underlying Paleogene and Cretaceous strata that significantly contribute to the estimation of ground motion in the event of a future large New Madrid seismic zone earthquake. The new ground motion maps using the three-dimensional geology of Dyer County are compared to the current U.S. Geological Survey earthquake hazard maps. This comparison reveals generally lower acceleration for buildings less than four stories high and greater acceleration for buildings greater than 10 stories high in the event of a large New Madrid seismic zone earthquake.

Two-dimensional inversion of CSAMT data and three-dimensional geological mapping for groundwater exploration in Tongkeng Area, Hunan Province, China

Controlled source audio-magnetotelluric (CSAMT) is an indirect and effective geophysical prospecting method in subsurface prospecting. Although CSAMT investigation tools are equipped with new techniques, it must be noted that the models obtained still do not automatically decipher the reality of groundwater in bedrock with very high resistivity contrasts. Our study proposed a new CSAMT data processing scheme, which combined the 2D modeling and 3D visualization for groundwater exploration in Tongkeng area, Hunan Province, China. To directly highlight exploitable groundwater, we used the open-source and the OCCAM2D inversion software, coupled with the geological information of the area to define the 3D imaging with emphasizing on the network of producing fractures. We deployed three CSAMT profiles with transverse magnetic (TM) mode recorded on 21 frequencies (8192 Hz to 8 Hz). The data were filtered, pre-processed and carefully analyzed from station to station. Analysis of the apparent resistivity and phase maps show the conductive zones (<150 Ωm) and resistive zones (> 500 Ωm) separated by transition zones (150 to 500 Ωm). The 2D models and stacked sections show discontinuities of fractures marked by two major faults and a main fracture in the zone interconnected by minor fractures. A 3D geological map was obtained from the result of the best models of the different lines. The ITER2DAT function was used to export the data from OCCAM2D inversion and then display it to array and depth channels data for each station. Geological and borehole ZK01 data were used to build pseudo stratigraphic drillholes based on the range of very low (<10 Ωm) to high values resistivity structures (>1500 Ωm). The 3D view shows stratigraphic discontinuity that is between carbonaceous formation and the metamorphic granites. The intruded Devonian limestone layer, which is the potential water tank, and the carbonate vein layer are constantly heated by the geothermal gradient of the area.

Three-dimensional geologic mapping to assess geothermal potential: examples from Nevada and Oregon

Geologic structure plays an important role in controlling fluid flow in geothermal systems. In particular, very complex structural settings, consisting of many closely spaced and intersecting faults, host many geothermal systems. To elucidate the key geologic factors that affect fault-controlled geothermal circulation, it is critical to precisely characterize the structural and stratigraphic geometries in these complex settings. Here, we present a methodology and the results of 3D geologic analyses of two geothermal systems in the Basin and Range, USA. This methodology is a quantitative and geologically focused technique that can be used to precisely characterize geothermal areas, in a time when future geothermal growth demands increased exploration precision and efficiency. Surficial and subsurface geologic and geophysical data are synthesized in the construction of detailed 3D geologic maps of geothermal areas. Based on these 3D geologic maps, we examine several geologic attributes that control permeability development and geothermal fluid flow along faults. We use the stress state of faults and the distribution of structural discontinuities (i.e., fault intersections and fault terminations) to identify locations of upflow along faults in these geothermal systems. These results and the methodology presented herein are directly applicable to structurally controlled geothermal fields in the Basin and Range and worldwide. As development focus shifts toward blind geothermal resources, integration of precisely characterized subsurface structural information into exploration methods will be increasingly critical to continued growth in geothermal exploration and development.

Using three-dimensional geological mapping methods to inform sustainable groundwater development in a volcanic landscape, Victoria, Australia

This study investigated the use of three-dimensional (3D) geological methods to provide better groundwater resource estimates for the Spring Hill area in central Victoria, Australia. Geological data were gathered in 3D geological software, which was utilised to derive fundamental dimensional parameters of the groundwater system in the study area. Mining industry software and hydrogeological methods were combined to give volumetric determinations of the basalt aquifer that were used to improve estimates of the groundwater resource. The methods reduce uncertainty about the physical attributes of the aquifer systems and greatly improve conceptual understanding of their behaviour. A simple numerical water-balance model was developed to refine the estimates of aquifer volume and fluxes to approximate observed water-level behaviour in the area. This enabled a much better comparison of groundwater resource use to the natural inputs and outputs for the area. A key conclusion was that the main issues for sustainable development and use in the study area are more to do with the physical aspects of the aquifer system, rather than simply the volume of water pumped. Visualisations of the area’s hydrogeology also provide improved hydrogeological understanding and communication for groundwater users and administrators.

地質図の3次元化に着目した地質情報の活用にかかわる研究の動向と課題

地質学には基礎科学としての側面と応用科学としての側面がある. 作成される地質図は地表と地下における自然現象を解明するとともに, 人類の社会, 経済活動に有用な情報を提供してきた. 地質図は, 古くから2次元で表現されてきたが, 近年のコンピュータの処理技術の向上とともに, 数値化が行われ, 3次元の地質図が作成されるようになってきている. 日本では地下情報のデータベース化が進められているため, 今後はこれらを活用した地質図の3次元モデルに関する研究が一つの主流となるものと考えられる. また, 情報技術の発達に伴う地質図の情報配信の変化は, 利用者の拡大と多様化をもたらしており, これまでの専門性の高さを失わずに, 利用者にとってよりわかりやすい情報配信が必要となっている. 利用者の要求を満たし, 情報の価値をより高めるため, 地質図の3次元化は有効な方策である. このため, これからの地質情報の配信においては, 3次元情報の配信を積極的に行っていくべきであろう. これらの背景から, 本論では地質図の表現方法の変遷や地質図の3次元モデル化に係る研究の動向と課題を抽出するとともに, 今後の方針について言及した.

Three-dimensional numerical geological mapping: Principles and computer programs for producing new generation maps

Three-dimensional numerical geological mapping: Principles and computer programs for producing new generation maps

Introduction to a Special Issue on Three-dimensional Geological Mapping for Groundwater Applications

Modern societies have increasing demands for contaminant remediation and a continued supply of potable water. This is particularly the case in the densely populated and industrialized parts of North America and Europe. Coping with the demand, however, requires optimal geologic mapping and modeling methods, and for hydrogeologists to generate improved model scenarios using the best available geological information. Unfortunately, there is often a lack of collaboration between geologists and hydrogeologists. Therefore, geological complexity and understanding is often under-represented in many groundwater models. This article introduces a special issue of the Journal of Maps focusing on three-dimensional (3-D) geologic mapping for groundwater applications. Four articles in the issue are based on papers that were presented at workshops held between 2001 to 2005. The workshops provided venues for researchers to share their expertise in constructing 3-D geological models and to discuss various geological issues pertaining to groundwater and urbanization. Primary topics discussed in the workshops and in these four Journal of Maps articles are basin analysis, data integration and management, three-dimensional geologic model construction, groundwater investigations, and communication. The four papers in this issue demonstrate different philosophical and technical approaches to the development of GIS based 3-D geological models, while the modeling approaches and results reflect various issues and data support problems inherent with model development at various scales, from large regional models, to intermediate scale municipal and county scale models, to site-specific scale.

Introduction to a Special Issue on Three-dimensional Geological Mapping for Groundwater Applications

Introduction to a Special Issue on Three-dimensional Geological Mapping for Groundwater Applications

3-D modeling of geologic maps from surface data

Recent discoveries in earth sciences are mostly related to technologies allowing graphical representations of volumes. We present a way to produce mathematically and geometrically correct three-dimensional (3-D) geologic maps consisting of the volume and shape of all geologic features of a given area. The method is innovative in that it only uses surface information based on the combination of a standard geologic map, a satellite image, and a digital elevation model. It is based on a modeling algorithm that only uses surfaces calculated from scattered data points and that intersects them following a series of geologically sound rules. The major advantage of using such technology is that it provides the user with a way to quantify geology. To illustrate how a 3-D geologic map can be computed, we explain the steps taken to build a dummy model with simple faulting and depositional sequencing. The case study chosen to illustrate the method is the Beirut watershed (Lebanon), an area with relatively simple geology. The 3-D visualization and cross sections help in the understanding of the geometrical relationship between the different geologic features, allowing a reexamination of the tectonic history of the area during the late Mesozoic.

Quaternary geological mapping of the lowlands of The Netherlands, a 21st century perspective

Old borehole descriptions, modern lithostratigraphical classification and geostatistics have been combined in recent geological mapping in The Netherlands. Recent developments in geostatistics and the increased computing capacity of personal computers enable three-dimensional geological mapping, based on already available data. The data originate from a mapping programme at the scale of 1:50,000 that was started in the 1950s by the National Geological Survey (Rijks Geologische Dienst). Although started on a lithostratigraphical basis, the increased use of radiocarbon dates since the 1950s influenced the map legend. The map units were largely defined by age boundaries that were supposed to coincide with transgressions and regressions. More recent research revealed that not only sea level but also regional basin topography, sediment supply and regional neo-tectonics are important factors controlling coastal development. The Netherlands Institute of Applied Geoscience TNO–– National Geological Survey (the successor of the Rijks Geologische Dienst) recently redefined the classification of Holocene coastal and alluvial deposits in a purely lithostratigraphical way. The old borehole descriptions contain purely lithological descriptions as well as interpretations that were derived from those descriptions. The larger part of the originally defined map units represents boundaries that characterise a change in lithology. By returning to the original lithological descriptions, the borehole data and the geological maps are applicable in the new lithostratigraphical framework. They are now used in modern three-dimensional geological mapping/modelling of the subsurface. These models are very useful for applied geological research.

On the reconstruction of three-dimensional complex geological objects using Delaunay triangulation

In the past four decades, huge amount of geologic data has been accumulated. Now it is time to integrate these geologic data with other sources of data, such as the digital elevation model (DEM) and remote sensing data, to do various analyses, 3D modelling, and real-time interactive visualisation to extract more meaningful results. Reconstruction of 3D geological objects is very important for geological research and mining. Traditional geologic maps that show structures and materials at the earth’s surface no longer are sufficient for storing, displaying, and transmitting geoscience information. Fully three-dimensional geologic maps are needed to provide users with geologic information of the quality, accuracy, and detail necessary to solve problems related to natural hazard mitigation, resource management, mineral and petroleum exploration, contaminant dispersion, and other issues. Although some data models and algorithms have been developed, there are few works on reconstruction of real 3D complex geological objects. In this paper, we apply Delaunay triangulation and tetrahedron for 3D reconstruction of geological structures with sudden changes. Since this technique is mainly used for 3D reconstruction of medical objects, follows that we provide a new field of application.

Tools for Groundwater Protection Planning: An Example from McHenry County, Illinois, USA.

/ This paper presents an approach for producing aquifer sensitivity maps from three-dimensional geologic maps, called stack-unit maps. Stack-unit maps depict the succession of geologic materials to a given depth, and aquifer sensitivity maps interpret the successions according totheir ability to transmit potential contaminants. Using McHenry County, Illinois, as a case study, stack-unit maps and an aquifer sensitivity assessment were made to help land-use planners, public health officials, consultants, developers, and the public make informed decisions regarding land use. A map of aquifer sensitivity is important for planning because the county is one of the fastest growing counties in the nation, and highly vulnerable sand and gravel aquifers occur within 6 m of ground surface over 75% of its area. The aquifer sensitivity map can provide guidance to regulators seeking optimal protection of groundwater resources where these resources are particularly vulnerable. In addition, the map can be used to help officials direct waste-disposal and industrial facilities and other sensitive land-use practices to areas where the least damage is likely to occur, thereby reducing potential future liabilities. KEY WORDS: Geologic mapping; Groundwater; Aquifers; Aquifer sensitivity; Land-use planning

Application of 3-D Geological Mapping to Site Horizontal Wells

Three-dimensional (3-D) geologic mapping using advanced graphics software was used on five horizontal well sites in the Appalachian basin to determine the optimum horizontal well locations and trajectories. This effort was applied in support of an active USDOE/METC program in drilling horizontal wells in the Devonian shales of the Appalachian basin. During preliminary assessments of the sites, a large quantity of geological, well log, and production data were acquired for the interpretation and graphical representation of the subsurface strata. The graphics provided a means of correlating the various reservoir parameters to determine the geologic conditions controlling the openness of the fractures and the best production fairways in a given area. The resulting models were used to determine the optimum location of the horizontal well with respect to the fractured reservoir orientation.

カラー立体地質図のコンピュータ作図処理

カラー立体地質図のコンピュータ作図処理

Three-dimensional geologic mapping: a basis for hydrologeologic and land-use evaluations : Kempton, J P; Cartwright, K Bull Assoc Engng GeolV21, N3, Aug 1984, P317–335

Three-dimensional geologic mapping: a basis for hydrologeologic and land-use evaluations : Kempton, J P; Cartwright, K Bull Assoc Engng GeolV21, N3, Aug 1984, P317–335