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| :::Fundamental and Environmental Geology |
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 The objective is to study the surface and subsurface geology of Taiwan and to present the results as geological maps that describe geological features such as the structure, stratigraphy, minerals, and paleontology. The CGS also undertakes projects across many sectors, including Quaternary studies, engineering and subsurface of metropolitan areas of Taiwan, research on slopelands surrounding major metropolises, and marine geology mapping offshore Taiwan. |
| A. |
Geological Mapping |
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The 1/50,000 scale geological map of Taiwan which contains the main island, Penghu volcanic archipelagos, and three islets (Liuciuyu, Lanyu, Lyudao), was subdivided into 76 contiguous quadrangles based on the official division of national topographic maps; among the 78 quadrangle maps, 49 have been published, 9 are ready for review, and 7 are under survey. Thirteen quadrangles covering the Central Range of Taiwan are still being prepared due to the access difficulties of the remote mountainous area.
In 2002, 1/25,000 scale geological maps of Jinmen islands and Mazu archipelagos were added to our mapping program.
In 2006, the CGS has completed the draft of the revision of "The Stratigraphic Code of ROC," which was originally published by the Geological Society of China (Taiwan) in 1960. This draft is expected to be reviewed by geological professionals in the country and will serve as an official guideline for geological investigation and stratigraphic classification and nomen-clature. |
| B. |
Quaternary Geological Investigation
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There are three main projects among Quaternary geological investigations this year: (1) Quaternary geological investigations of northern Taiwan, (2) late Quaternary geological and geomorphic study of eastern Taiwan, and (3) borehole investigations of the Changhua fault.
The first project has completed the analysis of physical and chemical properties of laterit-ic core sediments, data collection of borehole cores, and the Quaternary geological map of northern Taiwan.
The second project aims at collecting Quaternary geological data in eastern Taiwan to compile the Quaternary geological map of the area. Furthermore, the result of field investigation, combined with the data of paleoclimate change, will reconstruct the Late Quaternary geomorphic evolution of the CoastalRange. The working area in 2006 includes the coasts of Hualien and Taitung and the rivers of the eastern slope of the CoastalRange.Terraces were recognized from aerial photographs and mapped on 1/25,000 topographic maps.
According to field investigations and the four borehole data along the western margin of the Pakuashan area, the research team proposed that the northern segment of the Changhua Fault has thrust westward over the Changhua alluvial plain.The fault's lineament passes between the northern Pakua Tableland and the alluvial plain, where there would be a fault scarp. Meanwhile, the central and southern segments of the Changhua Fault remain as blind faults. |
| C. |
Investigation and Research on Engineering and Subsurface Geology
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From 2004, the CGS has implemented a six-year project to investigate the engineering and subsurface geology of the metropolitan areas.The second phase (2006 and 2007) focuses on Taichung, Changhua, Yunlin, Chiayi and Pingtung areas.
The study areas were mostly alluvial plains of Pleistocene age. The sedimentary environments, lithological strata distributions, and soil engineering properties showed great variability. Therefore, this study will utilize detailed borings and testing programs. The project is divided into four in-depth studies: (1) subsurface geology and lithology, (2) engineering geological properties of soils, (3) databank of borehole drillings, and (4) engineering environmental geological mapping and geological hazard susceptibility mapping.
Upon the completion of this project, geological grating profiles, liquefaction potential distributions, and geotechnical microzonation will be obtained for the Taichung, Changhua, Yunlin, Chiayi and Pingtung areas. These subsurface exploration data will be incorporated into establishing the Geo2005 Database System, which will be a valuable tool for understanding the geological environment and potential geotechnical problems, as well as land planning and hazard mitigation in Taiwan. |
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Databank Establishment on Integrated Environmental Geology Information of Slopelands Surrounding Major Metropolises
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As part of the program, the "Establishment of Environmental Geological Database for Disaster Prevention in the Slopeland of Taiwan," is a 5-year project and aims to identify the geological hazards on the slopelands and to establish geological environment data in the integrated Geographic Information Systems (GIS) database which is accessible on the Web. The project is divided into 4 sub-projects, which are the studies on slopeland rock mass engineering properties, the investigation on the geological hazards of slopeland, the investigation and database establishment for the mine areas, and the establishment of an integrated environmental and engineering geological database system.
The survey areas in 2006 were located in Hualien, Taitung, Taichung, Chunghua, Yunlin, and parts of Taipei, within which a total of 32 sheets of 1 to 25,000 scale topographical quadrangle maps were created, covering 4,267 km2. The maps also contain mining surveys of Hualien and Taitung, with the addition of measuring tunnel positions onto the original tunnel and excavation trace map data.
Moreover, the online database in this project will create a convenient inquiry system for telescope layer display, property inquiry, and map printing. |
| E. |
Marine geology mapping offshore Taiwan |
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The purpose of the marine geology mapping is to obtain the basic data of the current marine geology status, mineral resources, and potential geological hazards, in order to offer suggestions for the exploitation of the seas around Taiwan.
Owing to the lack of geological survey experience offshore Taiwan, two maps are select-ed to be drawn in order to provide better understating and useful information for the overall marine geological mapping. This two-year project includes two marine geology mappings and one marine sediment distribution mapping offshore Fu-guey-chiao (M10-1) in the northern part of Taiwan and offshore Wai-Siao-liou-ciou (M10-15) in the southwest part of Taiwan.In 2006, a marine geological map of M10-15 was drawn, while geophysics research was made for M10-1.
M10-15 with the coordinates of (22°30' N, 119°45' E), (22°30' N, 120°15' E), (20°N, 120°15' E), (22°N, 119°45' E) was also selected for"Geology Exploration of Gas Hydrate Prospects Offshore Southwestern Taiwan" research for its abundant geological data. The area includes Kaoping Shelf, Kaoping Slope, KaopingCanyon, and KaohsiungCanyon. However, the existing data is not sufficient for mapping out the stratun. More data collection is needed.
M10-1 with the coordinates of (25°30' N,121°30' E),(25°30' N,122°E),(25°N,122°E), (25°N, 121°30' E) is involved with a 658-kilometer long seismic data set collected for the 2007-mapping plan. |
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