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Beach ridges U-Th dating in Tongoy bay and tectonic implications for a peninsula-bay system, Chile,

Abstract : Along the Chilean coast, peninsulas associated with bays seem to behave as a complex system. They act as barrier to propagation of megathrust earthquakes along strike. To better understand how such a system works from ocean side to more inland, we investigated the area between the Tongoy bay and the Altos de Talinay in northern Chile (∼30°S). It represents a forearc peninsula-bay system in which a normal fault (Puerto Aldea fault) has been described as accommodating a relative vertical motion between the two parts, the peninsula being uplifted with respect to the bay. We dated shells from beach ridges by U-Th disequilibria in order to compare the bay area to the peninsula area for which 10Be dating of wave-cut platforms are available (Saillard et al., 2009). These indicate: (1) the Puerto Aldea fault activity probably ceased since at least ∼230 ka, implying the bay and peninsula parts are evolving together since then; (2) the uplift rate is variable and has decreased from ∼0.8 m/ka to ∼0.2 m/ka between ∼300 and 100 ka.
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https://hal.archives-ouvertes.fr/hal-01053109
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Submitted on : Tuesday, July 29, 2014 - 4:03:55 PM
Last modification on : Friday, January 8, 2021 - 10:12:03 AM

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Marc Saillard, J. Riotte, V. Regard, A. Violette, G. Hérail, et al.. Beach ridges U-Th dating in Tongoy bay and tectonic implications for a peninsula-bay system, Chile,. Journal of South American Earth Sciences, Elsevier, 2012, 40, pp.77-84. ⟨10.1016/j.jsames.2012.09.001⟩. ⟨hal-01053109⟩

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