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- Title
K-Ar Dating of Fault Gouges from the Red River Fault Zone of Vietnam.
- Authors
BUI, Hoang Bac; NGO, Xuan Thanh; SONG, Yungoo; ITAYA, Tetsumaru; YAGI, Koshi; KHUONG, The Hung; NGUYEN, Tien Dung
- Abstract
Constraining the timing of fault zone formation is fundamentally important in terms of geotectonics to understand structural evolution and brittle fault processes. This paper presents the first authigenic illite K-Ar age data from fault gouge samples collected from the Red River Shear Zone at Lao Cai province, Vietnam. The fault gouge samples were separated into three grain-size fractions (<0.1 µm, 0.1-0.4 µm and 0.4-1.0 µm). The results show that the K-Ar age values decrease from coarser to finer grain fractions (24.1 to 19.2 Ma), suggesting enrichment in finer fraction of more-recently grown authigenic illites. The timing of the fault movement are the lower intercept ages at 0% detrital illite (19.2 ± 0.92 Ma and 19.4 ± 0.49 Ma). In combination with previous geochronological data, this result indicates that the metamorphism of the Day Nui Con Voi (DNCV) metamorphic complex took place before ca. 26.8 Ma. At about 26.8 Ma-25 Ma, the fault strongly acted to cause the rapid exhumation of the rocks along the Red River-Ailoa Shan Fault Zone (RR-ASFZ). During brittle deformation, the DNCV slowly uplifted, implying weak movement of the fault. This brittle deformation might have lasted for ca. 5 Ma.
- Subjects
POTASSIUM-argon dating; METAMORPHISM (Geology); SHEAR zones; FAULT zones; STRUCTURAL geology; GEOLOGICAL time scales
- Publication
Acta Geologica Sinica (English Edition), 2016, Vol 90, Issue 5, p1653
- ISSN
1000-9515
- Publication type
Article
- DOI
10.1111/1755-6724.12808