O EOL GIC G A D D A E D C E I H C I L E O S F u n 2 da 9 6 Miocene and Early Pliocene a fresh-water lake formed in la serena octubre 2015 da en 1 the same region because of a wetter climate (Sáez et al., References Cited 2012). The subsequent return to hyperaridity terminated The link between coastal uplift in the Mejillones Peninsula the lake. Another cycle of diminished aridity followed by Allmendinger, R.W.; González, G.; Yu, J.; Hoke, G.D.; Isacks, B.L. renewed hyperaridity created the Soledad Formation salar 2005. Trench-parallel shortening in the northern Chilean forearc: and the subduction earthquake cycle from analytical during the Late Pliocene. There is no evidence of drainage tectonic and climatic implications. Geological Society of America by a major river like the Loa from the high Andes to the Bulletin 117(1): 89-104, doi:10.1130/B25505.1. Bao, R.; Sáez, A.; Servant-Vildary, S.; Cabrera, L. 1999. Lake-level models Pacific across the study area during either the Hilaricos or and salinity reconstruction from diatom analyses in Quillagua Soledad deposition. In contrast, during Quillagua time a Formation (late Neogene, central Andean forearc, northern Chile). Mahesh N. Shrivastava1*, Gabriel Gonzalez1, 2, Gabriel Vargas3, Jose Gonzalez3, Marcos Moreno4, Juan Gonzalez1, 2 paleo-Loa River fed the basin and the lake may have been Palaeogeography, Palaeoclimatology, Palaeoecology, 153(1-4): 309- 1National Research Center for Integrated Natural Disaster Management (CIGIDEN), Santiago, Chile an open system. But the location of an expected spill-point 335. 2Universidad Católica del Norte, Antofagasta, Chile. for the Quillagua lake has not been documented (Sáez et Carrizo, D.A.; González L., G.; Dunai, T.J. 2008. Constricción 3Departamento de Geología, Universidad de Chile, Chile Neógena en la Cordillera de la Costa norte de Chile: Neotectónica y 4 al., 1999). We propose that the east-trending set of faults 21 GFZ Helmholtz Centre Potsdam, German Research Centre for Geosciences, Germany datación de superficies con Ne cosmogénico. Revista Geologica De between 21°10’–21°40’S (Fig. 1) provided low topography Chile, 35(1): 1-38, doi:10.4067/S0716-02082008000100001. and weakened rock which were utilized by overspill from Cosentino, N.; Jordan, T.E. 2012. 87Sr/86Sr en paleosuelos salinos *Contact email: [email protected] the Quillagua lake system. Although the paleo-Loa likely como paleoaltímetro; resultados preliminares para el norte de Chile did not drain through this basin during Soledad time, (19-22°S), In Congreso Geológico Chileno 13, 669-671, Antofagasta, groundwater leaked from the southern part of the Soledad Chile. Abstract. The Mejillones Peninsula in Northern Chile earthquake for vertical upliftment. So, we have simulated Cosentino, N.J.; Jordan, T.E.; Derry, L.A.; Morgan, J.P.. In review. shows evidence of uplift during the Quaternary. Continuous salar system may have further weathered the relict Loa an earthquake of maximum slip 8.8m equivalent to the 87Sr/86Sr in recent accumulations of calcium sulfate on landscapes GPS stations in this peninsula show that vertical moment deficit. Canyon. of hyperarid settings as an altitude proxy: results for northern Chile displacement varies significantly during the subduction (19.5-21.5°S). Geochemistry Geophysics Geosystems. earthquake cycle. GPS time series since 2002 to the The three phases of the subduction earthquake cycle, We hypothesize that several hundred meters of tectonic Jordan, T.E.; Kirk-Lawlor, N.E.; Blanco, N.; Rech, J.A.; Cosentino, present indicate subsidence or null vertical displacement N.J. 2014. Landscape modification in response to repeated onset of interseismic coseismic and postseismic is a non-periodic subsidence since ~4 Ma led again to capture of both local during the interseismic phase. In contrast surface uplift has hyperarid paleoclimate states since 14 Ma, Atacama Desert, Chile. cyclic process. In each phase the interface behaves and regional drainage systems. Since that time surface occurred during the coseismic phase of the last two great Geological Society of America Bulletin 126, B30978-B30971. extremely different. The interseismic period is the largest water and ground water flow have been focused through subduction earthquakes (the 1995, Mw 8.1 Antofagasta Jordan, T. E.; Nester, P. L.; Blanco, N.; Hoke, G. D.; Dávila, F.; period that can take over hundreds years for an Mw 8.5 the Quillagua-Llamara area. The north-trending paleo- Tomlinson, A. J. 2010. Uplift of the Altiplano-Puna Plateau: A View earthquake and the 2007, Mw 7.7 Tocopilla earthquake). channels that parallel the Loa between Chacance and from the West. Tectonics 29 (TC5007), doi:10.1029/2010TC002661. We postulate that the distribution of interseismic coupling earthquake. During this period the deformation of the Quillagua may be relicts of initial attempts to re-connect Nester, P. (2008) Basin and Paleoclimate Evolution of the Pampa del along the megathrust plays a major role in character of the overriding plate is controled by interplate coupling and the Loa headwaters to the Quillagua-Llamara sub-basin Tamarugal Forearc Valley, Atacama Desert, Northern Chile, Cornell vertical displacement. In order to test this hypothesis, we modelled as a variation of back-slip velocity in the late in Soledad Formation time. Their pattern is consistent University, Ph.D. Dissertation, 253 p. model vertical displacement using the coupling at the plate megathrust surface. The second phase is the coseismic Nester, P. L.; Jordan, T.E. 2012. The Pampa del Tamarugal Forearc interface. We simulated the interseismic phase by applying period. It is the shortest phase of seismic cycle. In this with a long-lived northward inclination of the southern Basin in Northern Chile: The Interaction of Tectonics and Climate, In back slip analysis and also we simulated the coseismic period the stored seismic energy is released in some flank of the region of latest Pliocene–Quaternary tectonic Tectonics of Sedimentary Basins: Recent Advances (Busby, C.; Azor, subsidence. A.; editors). Blackwell Publishing Ltd: 369-381. Oxford, England. phase by transforming the interseismic coupling in slip seconds in the form of earthquakes. Strain release produce deficit. We also delineated the vertical displacement from extreme horizontal and vertical deformation at the earth Quezada, A.; Vásquez, P.; Sepúlveda, F. 2013. Soledad Formation: detailed mapping and radiometric ages, In International Geological the time series of GPS sites during the postseismic phase surface, strain rate became a maximum. The third phase of Congress on the Southern Hemisphere 2, (GEOSUR 2013). and find out the average relaxation time. The result our seismic cycle is the postseismic period. It is a phase of Acknowledgements Bollettino di Geofísica teorica ed applicata 54 (Supplement), 242. analysis indicate that the upliftment in the coseismic and relaxation. Sáez, A.; Cabrera, L.; Garcés, M.; Bogaard, P.; Jensen, A.; Gimeno, postseismic phase contribute positively whereas The U.S. National Science Foundation supported this D. 2012. The stratigraphic record of changing hyperaridity in the interseismic counterbalance it. Atacama desert over the last 10 Ma. Earth and Planetary Science In the Mejillones Peninsula Quaternary uplift is recorded research (EAR-0208130, EAR-0609621 and EAR- as geological process with long-term rate of 0.5 mm/yr Letters 355: 32-38. Keywords:Mejillones, GPS, 1049978). The authors benefited from shared field work Sáez, A.; Cabrera, L.; Jensen, A.; Chong, G. 1999. Late Neogene (Marquardt et al., 2004). Unpublished evidence show with Nicolás Blanco, Andrew Tomlinson, Fernando lacustrine record and palaeogeography in the Quillagua-Llamara ! coastal upift of 1 mm/yr. Adding coseismic and Sepúlveda, Paulina Vasquez, and Andrés Quezada of basin, Central Andean fore-arc (northern Chile). Palaeogeography, 1 Introduction interseismic uplift results in an expected surface uplift Palaeoclimatology, Palaeoecology 151(1): 5-37. SERNAGEOMIN. We thank Antonio Díaz for managing anomaly that overcomes the geological uplift by at least the field work logistics. Mejillones peninsula has been shown as the topographic two orders of magnitude. It indicates that the unexpected expression of a segment boundary of subduction uplift may be a transient effect counterbalanced by other earthquakes (Victor et al., 2011). From the long-term process. In this contribution we try to characterize the geological appearance, Mejillones Peninsula is relationship between vertical displacements of the coastal characterized by the existence of active normal faults and region with the subduction earthquake cycle. In this surface upliftment (Niemeyer et al., 1996; Delouis et al., analysis, we utilise the elastic behaviour of Earth. We will 1998, González et al., 2003 and Cortés et al., 2012). improve our model with elastic and plastic behaviour of Loveless et al. 2010 using InSAR data have measured in Earth. the adjacent region of Mejillones Peninsula more than 15 cm of uplift during the two most recent earthquakes that 2 Tectonic and structural setting occurred (Antofagasta 1995 and Tocopilla 2007). In addition, GPS time series after the 2007.Tocopilla In the region of Mejillones peninsula, Northern Chile the earthquake shows postseismic uplift more than one year. convergence between the Nazca and South American The vertical upliftment is observed in the Tocopilla plates is occurring at a convergence velocity of 65 mm/yr earthquake around 11% of the moment deficit during the along a vector oriented N75°E (Angermann et al., 1999). interseismic period. It is hypothesis that still it has Convergence produces seismic interaction at the plate 4 sufficient moment deficit to provide a significant 298 AT 1 GeoloGía ReGional y Geodinámica andina interface along a seismogenic zone, extending from near As the displacement time series u(t) of horizontal and the trench to a down-dip limit located between 40 km and vertical components of position consists of: (a) a linear 55 km depth (Chlieh et al., 2004; Comte and Suarez, 1994; term representing plate motions.