Controls on turbidite deposition offshore the Chilean convergent margin

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Recurrence rates of giant subduction-zone earthquakes are still highly uncertain on centennial to millennial time scales along the rupture zone of the recent Chilean earthquake (Maule region, 2/27/2010; M=8.8), but are of utmost importance for seismic hazard prediction. Turbidite frequency has been used to reveal earthquake recurrence intervals along seismically hazardous continental margins but these results are still strongly debated. Only if the controls on turbidite deposition are well understood, the compilation of a turbidite paleoseismologic record can be successful. To establish recurring seismicity as a trigger for turbidity currents, synchronous deposition of turbidites in widely spaced, isolated depocenters has to be demonstrated. The main purpose of this study is to evaluate the relative contributions and history of controls on Holocene turbiditic sediment flux within two climatic zones along the Chilean margin. The development of a holistic model of deep-marine sedimentation focusing on terrestrial and submarine components and their interactions will allow to evaluate the feasibility of compiling a turbidite paleoseismologic record. If the Chilean margin proves to be a suitable place, such a record for two seismotectonic segments will be compiled. The proposed approach entails obtaining: (1) robust geochronologic constraints of the timing of turbidite layers, (2) correlation of turbidite ages and depositional rates to records of on- and offshore forcings, and (3) to test for coeval turbidite deposition in 7 depocenters to compile a paleoseismologic record for the Maule (34º-38ºS) and an adjacent rupture zone (30º-32ºS).