Hydro-isotopic (234U/238U) zoning of groundwaters in the seismically active southern margin of the Siberian craton, Russia
Abstract
The southern margin of the Siberian craton, which experienced severe tectonic deformations in the Neoproterozoic-Cambrian and Jurassic, is currently a part of the Baikal seismic belt. In groundwater budget of the area, the main contribution is provided by the homogeneous South Baikal reservoir (SBR) with 234U/238U activity ratio (AR) 1.95-1.99 and U concentration 0.44-0.46 µg/L. Lateral penetration of the SBR water from the hydrostatically loaded deeper part of the lake (1000 m and more) to the adjacent Siberian craton area is promoted by gentle ruptures of the Angara thrust fault and sub-vertical shear fissures of the Main Sayan suture zone. In order to predict the time and place of a strong earthquake, AR are determined in groundwater from craton basement and sedimentary cover in an area from Lake Baikal to Irkutsk. AR values associated with deformational (Cherdyntsev-Chalov) effect vary from 1.0 to 3.5. Chemical impacts in evaporates result in AR values as high as 16. Data of a 7-year monitoring show key points in AR variations that might be used for prediction of a future strong earthquake.This work is supported by the RSF grant 18-77-10027.
- Publication:
-
EGU General Assembly Conference Abstracts
- Pub Date:
- May 2020
- DOI:
- 10.5194/egusphere-egu2020-12963
- Bibcode:
- 2020EGUGA..2212963R