| Summary: | 碩士 === 國立成功大學 === 地球科學系 === 84 === Abstract The deformation of Tungho Limestone and Kangkou
Limestone in the Coastal Range of eastern Taiwan are studied
through field observation of fractures, stylolites, and faults
and laboratory analysis of calcite twin , stylolites and fault-
slip data. Three principal stress directions which inferred
from data of calcite twin, stylolites, and fault slip are all
consistent with the stress state at present. This indicates
that all mesoscopic structures formed when the Luzon volcanic
arc system of the Philippine Sea plate collides with the
Eurasian Continent plate. The plunge of the maximum principal
stress (σ1) is close to horizontal and trends in the range of
98 ~ 145 degrees in azimuth. The magnitudes of σ2 and σ3 are
close and they are interchangeable which indicates that both
thrusts and strike-slip faults are seen in deformed limestones.
According to the sross cutting relationship and unfolding of
tilted strata,most stylolites developed at initial stage and
followed by mechanical twinning when limestone beds are
horizontal. In addition,faulting and fracturing are conspicuous
at the late stage of the deformation after limestones are
tilted. In calcite twin analysis , the percentage of calculated
negative expected values are all smaller than 40% which indicate
the limestones have suffered a co-axial strain history (Teufel,
1980). Besides, the directions of principal stress are
consistent with those of principal strain in calcite twin
analysis which agree with the result of a co-axial strain
history. Consequently, geological structures of the Coastal
Range in eastern Taiwan probably refelt a pure shear strain
state according to the stress and strain state in the deformed
limestones.
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