Structural geology of the Uthai Thani limestone ridge within the Chainat duplex, Thailand

Abstract

Uthai Thani limestone ridge, which is located in Changwat Uthai Thani, lies in N-S direction on the central plane of Thailand. It is a southwestern part of Chainat duplex. Below the Mae Ping fault zone. This ridge is a part of Uthai Thani limestone. It is consist of Permian limestone. The evidences of macroscopic, mesoscopic and microscopic scales can be combined for the structural style of the Uthai Thani limestone ridge. Remote sensing interpretation show major lineament trends to N-S composite and minor NE-SW and ENE-WSW that conform to bed, fault, fracture and joint. The limestone was developed by sinistral ductile shear motion that was shown by sigmoid texture in calcite and chert nodule with strain shadow in outcrops and thinsection. Deformation of limestone widely spread which shown by stylolites, kink bands, the recrystallisation of twin boundary migration and bulging (BLG) recrystallisation. The temperature gauge of calcite twin geometry indicates temperatures at above 200 oC. In part of brittle deformation, dip slip fault was found and related with tend of bedding. All of characteristic of structural geology fit with the flexural slip and flexural shear fold models and the sinistral shear relates with the Chainat duplex and the Mae Ping fault zone during Tertiary.