SUMMARY
ESR dating of fault gouge in the midstream Thu Bồn river: New evidence of fault movements during late
Pleistocene-Holocene
Nguyễn
Quốc Hưng, Vũ Anh Đạo, Ngô Xuân Thành, Trần
Thanh Hải, Đặng Văn Bát
The main course of the Thu Bồn river system flows
through Nam Trà Mi, Bắc Trà Mi, Hiệp Đức, Nông Sơn,
Duy Xuyên, Điện Bàn, Hội An and outlets to the sea at Cửa
Đại. The river system has been changing drastically its flow in
recent years, causing landslide, sedimentation, droughts and floods. The The course of river system is changed due to different
causes, of which, endogenous geological activities such as tectonic
displacement of the active faults play an important role. Field studies have
identified a number of fault systems that exist in the study area, including
many large systems, spanning dozens of kilometers across the entire study area.
Dynamic analysis shows that four fault systems in the area are part of a
regional Riedel right-sided slip system. Three samples in the fault gouge of
the fault systems that cut through the midstream Thu Bồn river were collected to determine their faulting age by
Electron Spin Resonance (ESR) method, yielding 10282 years, 15409 years and
17689 years. These results show that the movement of the fault systems in the
midstream Thu Bồn river occurred during Late Pleistocene - Holocene, in
which the last active phase occurred at least 10,000 years ago.
Keywords: Quảng Nam; Thu Bồn river; ERS method; active Fault