| dc.description.abstract | In this study , the electric formations between Rui-sui and Chi-shang of the Taitung Longitudinal Valley are studied . The geological structures and the situations of the strata of the Central Range and the Costal Range under the Taitung Longitudinal Valley are studied also .
The DC resistivity method was used to investigate three area : Rui-sui , Yu-li and Chi-shang , with six geoelectric sounding profiles across the Taitung Longitudinal Valley . The sounding date were interpreted with 2-D inversion .
The geoelectric sounding profile AA’situated at the Rui-sui area , and profile BB’, CC’, DD’ situated at the Yu-li area , and profile EE’, FF’ situated at the Chi-shang area . The dipole-dipole array is used for profile AA’, EE’,and pole-pole array is used for profile BB’, CC’, DD’and FF’. All of the geoelectric sounding profiles are almost vertical to the straight of the Taitung Longitudinal Valley .
Several conclusions can be drawn as follows :
( 1 ) The results indicate that the alluvium in the middle of the valley is the thickest , and it is about few tens meters to 300 meters thick and has a resistivity ranging from 500 to 800 ohm-m .
In three area , the alluvium of Rui-sui is about 100 to 200 meters thick and has a resistivity ranging from 500 to 800 ohm-m . The alluvium of Yu-li is about 200 to 350 meters thick and has a resistivity ranging from 500 to 1000 ohm-m . The alluvium of Chi-shang is about 250 to 350 meters thick and has a resistivity ranging from 500 to 800 ohm-m .
( 2 ) Under the alluvium , the second layer is a low resistitity layer . The second geoelectric layer is composed of debris , which come from the coastal Range for the east .
The second geoelectric layer of Rui-sui is more than 600 meters thick and has a resistivity ranging from 30 to 60 ohm-m , and the second geoelectric layer of Chi-shang is about 300 to 400 meters thick and has a resistivity ranging from 30 to 100 ohm-m .
( 3 ) Under the second geoelectric layer , the third geoelectric layer is a high resistitity layer . It is presumed of the basement of the valley , which are composed of slate and schist .
For the Rui-sui area ,the depth of the top of the basement varies from 500 to 600 meters and has a resistivity ranging from 200 to 700 ohm-m . For the Chi-shang area , the depth of the top of the basement varies from 500 to 700 meters and the resistivity of Chi-shang is more than 500 ohm-m .
( 4 ) According to the result of geoelectric sounding profiles , there are discontinuities exist in the east part of the valley , which are presumed to be the places of the Costal Range fault . | en_US |