U-series dating of co-seismic gypsum and submarine paleoseismology of active faults in Northern Chile (23°S)

Gabriel Vargas, Carlos Palacios, Martin Reich, Shangde Luo, Chuan Chou Shen, Gabriel González, Yi Chen Wu

研究成果: Article同行評審

12 引文 斯高帕斯(Scopus)

摘要

The convergence of the Nazca and South American plates along the subduction margin of the central Andes results in large subduction earthquakes and tectonic activity along major fault systems. Despite its relevance, the paleoseismic record of this region is scarce, hampering our understanding about the relationship between the Andes building and earthquake occurrence. In this study, we used the U-series disequilibrium method to obtain absolute ages of paleoearthquake events associated with normal displacements along the active Mejillones and Salar del Carmen faults in the Coastal Range of the Atacama Desert of northern Chile. The 230Th-234U disequilibrium ages in co-seismic gypsum salts sampled along the fault traces together with marine evidences indicate that earthquakes occurred at ca. 29.7±1.7ka, 11±4ka and 2.4±0.8ka. When coupled with paleoseismic marine and radiocarbon (14C) records in the nearby Mejillones Bay evidencing large dislocations along the Mejillones Fault, the geochronological dataset presented here is consistent with the notion that gypsum salts formed during large earthquakes as a result of co-seismic dilatancy pumping of saline waters along the major faults. Based on maximum observed cumulative vertical offsets in the studied faults, this phenomena could have occurred episodically at a rate in the order of 1:40 to 1:50 with respect to the very large subduction earthquakes during the latest Pleistocene-Holocene period. The results presented here reveal that the U-series disequilibrium method can be successfully applied to date the gypsum salts deposited along faults during seismic events, and therefore directly constrain the age of large paleoearthquakes in hyperarid and seismically active zones.

原文English
頁(從 - 到)34-44
頁數11
期刊Tectonophysics
497
發行號1-4
DOIs
出版狀態Published - 2011 一月 2

All Science Journal Classification (ASJC) codes

  • 地球物理
  • 地表過程

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