Journal
SCIENCE CHINA-EARTH SCIENCES
Volume 59, Issue 12, Pages 2389-2410Publisher
SCIENCE PRESS
DOI: 10.1007/s11430-016-5334-4
Keywords
Yilan-Yitong Fault Zone; Origin structures; Sinistral ductile shear belts; Microstructures; Earliest Early Cretaceous
Categories
Funding
- National Natural Science Foundation of China [41472186, 91414301]
Ask authors/readers for more resources
The NE-striking Yilan-Yitong Fault Zone (YYFZ) with a length of ca. 900 km is an important major fault zone in northeastern China. Its origin has been a controversial issue for a long time. Detailed field investigation and comprehensive analyses show that strike-slip faults or ductile shear belts exist as the origination structures on the both shoulders of the Cretaceous- Paleogene grabens. These strike-slip structures are dominated by brittle transcurrent faults, and appear as ductile shear belts only in the Weiyuanpu-Yehe and Shulan parts in the south and middle of the fault zone, respectively. The shear belts strike NE-SW and show steep mylonitic foliation and gentle mineral elongation lineation. Outcrop structures, microstructures and quartz c-axis fabrics demonstrate a sinistral shear sense with minor reverse component for the ductile shear belts. The microstructures suggest deformation temperatures of 400-450A degrees C for the Weiyuanpu-Yehe shear belts and 350-400A degrees C for the Shulan shear belt. A series of zircon U-Pb dating results for deformed and undeformed plutons or dikes in the shear belts constrain the strike-slip motion to the time between 160 and 126 Ma. It is further inferred from ages of main geological events in this region that the fault zone originated in the earliest Early Cretaceous. It is suggested therefore that the southern and middle parts of the Tan-Lu Fault Zone, which originated in Middle Triassic, propagated into northeastern China along the sinistral YYFZ under the earliest Early Cretaceous regional compression that is referred to as the Yanshan B event. The earliest Early Cretaceous initiation of the YYFZ results from both the high-speed oblique subduction of the Izanagi Plate and the final closure of the Mongol-Okhotsk Ocean, but the Izanagi Plate subduction played a major dynamic role in the fault zone origin.
Authors
I am an author on this paper
Click your name to claim this paper and add it to your profile.
Reviews
Recommended
No Data Available