Tensile Fractures and In‐situ Stress Measurement Data Constraints on Cretaceous–Present Tectonic Stress Field Evolution of the Tanlu Fault Zone in Shandong Province, North China Craton

Abstract

Tectonic stress fields are the key to driving tectonic events and evolution of regional structures. The tectonic stress field evolution of the Tanlu fault zone in Shandong Province, located in the east of the North China Craton (NCC), may have preserved records of the NCC tectonics. Borehole television survey and hydraulic fracturing were conducted to analyze the paleo and present tectonic stress fields. Three groups of tensile fractures were identified via the borehole television, and their azimuths were NNW‐SSE, NW‐SE, and NE‐SW, representing multiple stages of tectonic events. Hydraulic fracturing data indicate that the study region is experiencing NEE‐SWW‐oriented compression and nearly‐N‐S‐oriented extension in accordance with the strike‐slip and compression. Since the Cretaceous, the orientation of the extensional stress has evolved counterclockwise and sequentially from nearly‐NW‐SE‐oriented to NE‐SW‐oriented and even nearly‐N‐S‐oriented, and the stress state has transitioned from strike‐slip‐extension to strike‐slip‐compression in association with the rotating and oblique subduction of the Pacific Plate beneath the NCC and the participation of the Indian Plate.