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Uplifted Plio-Pleistocene reefal limestones in southwestern Taiwan record the recent and present-day strain field in the foreland of the active Taiwan collision belt. On the basis of coaxial deformation and maximum resolved shear stress, the paleostress field can be inferred from the measured strain data. The study utilitizes Groshong''s strain-gage technique coupled with Spang''s numerical dynamic analysis to inferthe paleostrain and paleostress in southwestern Taiwan. Additional limestone samples were collected in the quarry of the Chihkoshan area in Chutung to investigate the temporal and spatial variations in both strain and stress fields. Results indicate that except samples from Chutung, the magnitude ofcalcite twinning strain increases from south to north or with increasivethe age of the limestone. Regarding the azimuth of the principal stressand strain axes, the Kungtien Limestones in Chiayi show two phases of orthogonal strain field. One of the maximum shortening strain-axis is SE-NW direction (115°~142°) and another is in the NE-SW direction (14°~55°). Samples from the Chentoushan to Niushan area in Tainan indicate only one phase of inhomogeneous stress. The maximum shortening strain-axis is in the SEE-NWW direction (113°~135°). West of the Kaohsiung area, one phase of stress was found with the maximum shortening strain-axis in the SEE-NWW direction (94°~124°). Among the area in Shoushan, Fengshan and Hengchun in Pingdon, the strain tensors reveal a maximum shortening strain-axis is in the N-S direction (149° ~224°) and a corresponding one phase of inhomogeneous stress. In the Chihkoshan area, samples show one phase of stress, and the maximum shortening strain-axis is in the SEE-NWW direction (111°~132°). In summary, all samples collected from southwestern Taiwan show a set of the maximal compressional stress axes with SE or SEE direction, which is consistent with the present-day tectonic stress.
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