Abstract
Geological maps are commonly used to investigate the distribution of geological natural resources, such as minerals. However, the existing 1:200,000 geological map created in the 1990s for Guangxi, China, cannot support efficient investigation and interpretation of the geological surface changes. Therefore, we propose the application of remotely sensed multispectral imagery to update the existing 1:200,000 geological map at a scale of 1:100,000. To this end, the analysis of the spectral characteristics of six types of lithologies from the USGS spectral library and from actual measurements by Field Spec®4, ASD Inc. is conducted first. With the analyzed results of the spectral characteristics, the carbonate rock is separated from the other rocks using band ratios, and then the study area is separated carbonate and noncarbonate areas. In the noncarbonate area, five types of rocks, named, shale, marble, sandstone, granite, and basalt, are classified using supervised classification, in which the training data sets are from the 1:200,000 geographic map. The field verification of the classified results shows that a classification accuracy of 66% is reached, which meets the accuracy requirement for the creation of 1:100,000 geological maps on that basis of the standard formulated by China Geological Map Remote Sensing Interpretation technology. The 1:100,000 geological map created will be delivered to the Guangxi Geological Bureau, China, for applications by the geological and remote sensing communities.
Highlights
The geological map of Guangxi Province in China was made at a scale of 1:200,000 in the end of the 20th century using early very-low-resolution remotely sensed image classification and field investigation
The classification accuracy with 66% can meet the requirement of 1:100,000 geological mapping, which is referenced to the Standard of China Geological Map Remote Sensing Interpretation Technology.[29]
The remotely sensed Landsat 7 ETM+ imagery in combination with the existing 1:200,000 geological map was applied to study the spectral characteristics of six types of rocks
Summary
The geological map of Guangxi Province in China was made at a scale of 1:200,000 in the end of the 20th century using early very-low-resolution remotely sensed image classification and field investigation. The scale of the 1:200,000 geological map should be updated to 1:100,000 The prerequisite for this task is that the types and coverage areas of each lithologic rock in Guangxi, China, should be obtained. Since the early 1980s, many investigators worldwide, such as Schetselaar et al.,[1] Gomez, et al.,[2] Zhang et al.,[3] Vaughan et al.,[4] and Hunt,[5,6,7] made considerable efforts to map minerals from remotely sensed imagery. These methods can be categorized as follows
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