QUANTITATIVELY DECIPHERING PALEO-STRAIN FROM DIGITAL OUTCROP MODELS: A CASE STUDY FROM THE EASTERN TIAN SHAN, CHINA

Fracture/fault slip data has long been used to calculate the paleo-strain/stress. Recent development of techniques for automatic extraction of fracture surfaces from digital outcrop models and estimation of historical shear deformation on rock fractures provide an efficient way of quantitatively acquiring large amount of high quality fracture/fault slip data from outcrops. This study shows how to interpret these data. The strain tensors of the slip data are grouped into populations corresponding to far-field strain events and local strain events using a clustering analysis technique. The results from outcrops in the eastern Tian Shan area give a clear picture of the paleo-strain variation over space and time, and also throw light on the relationship between paleo-strain, fracture development and different rock formations in a thrusting environment.