Geomorphological and dating investigations through the active structures on the Kueichungchi River, southwestern Taiwan
Date Issued
2005
Date
2005
Author(s)
Hsien-Ching, Chang
DOI
zh-TW
Abstract
In this study, I will use terrace landform and geological dating information to
investigate the active structural characteristics of the Kueichungchi area, southwestern
Taiwan.
Within the studied area, the active geological structures are the Liucha fault, the
Peishikeng fault, the Chunkeng fault, the Lunhou fault, the Niushan anticline and the
Chientapu syncline.
For the nature of the geological structures, the Liucha fault, the Chunkeng fault
and the Lunhou fault are referred to as forward thrusting structures, the Peishikeng
fault as a back thrust structure and the Niushan anticline and the Chientapu syncline
as fault-related fold structures. Towards the east and west of the Luchia fault, low and
flat fluvial plain and undulated hilly land alternately display the geomorpholgical
characteristics of the region.
In general, higher topographic terrain could be correlated with the frontal portion of
the thrust structures and/or the axial portion of the anticline structures. Furthermore,
the general flowing direction and pattern of the river change depending on the active
geological structures encountered.
Large population of river terraces with various altitudes ranging from 4.5 to
135 meters could be identified along the Kueichungchi. Four to five levels of river
terraces could be grouped in the Niushan anticline region and 3 levels of river terraces
in the Chientapu syncline region, respectively.
Radioactive carbon age dating of the river terraces shows that the axial portion of
the Niushan anticline with the age 31880 B.P. could be correlated with the Chientapu
syncline with the age of 35810 B.P. of similar time span. These two river terraces are
not only correlatable for having the same age span of 31880 B.P. and
35810 B.P., respectively, but also for having similar degrees of slight red soil
development.
The river incision rate of the last 30 ky for the Niushan anticline and the
Chientapu syncline is 2.8 mm/yr and 0.06 mm/yr respectively.
Thus, the uplift rate for the Niushan anticline area is much larger than that for the
Chientapu syncline area.
Thus, the significance of active structures on the development of landform along
the Kuiechungchi drainage area in the southeastern Taiwan is well exhibited.
In the studied area, regional development of the geomorphological characteristics
is closely related to the active geological structures.
Subjects
龜重溪
active structures
Type
thesis
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