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189 results on '"Contreras-Reyes, Eduardo"'

151. Cenozoic Uplift and Exhumation of the Frontal Cordillera Between 30° and 35° S and the Influence of the Subduction Dynamics in the Flat Slab Subduction Context, South Central Andes

Author

Lossada, Ana C., Giambiagi, Laura, Hoke, Gregory, Mescua, José, Suriano, Julieta, Mazzitelli, Manuela, Blondel, Philippe, Series Editor, Guilyardi, Eric, Series Editor, Rabassa, Jorge, Series Editor, Horwood, Clive, Series Editor, Folguera, Andrés, editor, Contreras-Reyes, Eduardo, editor, Heredia, Nemesio, editor, Encinas, Alfonso, editor, B. Iannelli, Sofía, editor, Oliveros, Verónica, editor, M. Dávila, Federico, editor, Collo, Gilda, editor, Giambiagi, Laura, editor, Maksymowicz, Andrei, editor, Iglesia Llanos, María Paula, editor, Turienzo, Martín, editor, Naipauer, Maximiliano, editor, Orts, Darío, editor, D. Litvak, Vanesa, editor, Alvarez, Orlando, editor, and Arriagada, César, editor

Published
2018
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152. The Late Oligocene–Early Miocene Marine Transgression of Patagonia

Author

Encinas, Alfonso, Folguera, Andrés, Bechis, Florencia, Finger, Kenneth L., Zambrano, Patricio, Pérez, Felipe, Bernabé, Pablo, Tapia, Francisca, Riffo, Ricardo, Buatois, Luis, Orts, Darío, Nielsen, Sven N., Valencia, Victor V., Cuitiño, José, Oliveros, Verónica, De Girolamo Del Mauro, Lizet, Ramos, Victor A., Blondel, Philippe, Series Editor, Guilyardi, Eric, Series Editor, Rabassa, Jorge, Series Editor, Horwood, Clive, Series Editor, Folguera, Andrés, editor, Contreras-Reyes, Eduardo, editor, Heredia, Nemesio, editor, Encinas, Alfonso, editor, B. Iannelli, Sofía, editor, Oliveros, Verónica, editor, M. Dávila, Federico, editor, Collo, Gilda, editor, Giambiagi, Laura, editor, Maksymowicz, Andrei, editor, Iglesia Llanos, María Paula, editor, Turienzo, Martín, editor, Naipauer, Maximiliano, editor, Orts, Darío, editor, D. Litvak, Vanesa, editor, Alvarez, Orlando, editor, and Arriagada, César, editor

Published
2018
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153. Neogene Growth of the Patagonian Andes

Author

Folguera, Andrés, Gianni, Guido M., Encinas, Alfonso, Álvarez, Orlando, Orts, Darío, Echaurren, Andrés, Litvak, Vanesa D., Navarrete, César R., Sellés, Daniel, Tobal, Jonathan, Ramos, Miguel E., Fennell, Lucas, Fernández Paz, Lucía, Giménez, Mario, Martínez, Patricia, Ruiz, Francisco, Iannelli, Sofía B., Blondel, Philippe, Series Editor, Guilyardi, Eric, Series Editor, Rabassa, Jorge, Series Editor, Horwood, Clive, Series Editor, Folguera, Andrés, editor, Contreras-Reyes, Eduardo, editor, Heredia, Nemesio, editor, Encinas, Alfonso, editor, B. Iannelli, Sofía, editor, Oliveros, Verónica, editor, M. Dávila, Federico, editor, Collo, Gilda, editor, Giambiagi, Laura, editor, Maksymowicz, Andrei, editor, Iglesia Llanos, María Paula, editor, Turienzo, Martín, editor, Naipauer, Maximiliano, editor, Orts, Darío, editor, D. Litvak, Vanesa, editor, Alvarez, Orlando, editor, and Arriagada, César, editor

Published
2018
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154. Cretaceous Orogeny and Marine Transgression in the Southern Central and Northern Patagonian Andes: Aftermath of a Large-Scale Flat-Subduction Event?

Author

Gianni, Guido M., Echaurren, Andrés, Fennell, Lucas, Navarrete, César R., Quezada, Paulo, Tobal, Jonathan, Giménez, Mario, Dávila, Federico M., Folguera, Andrés, Blondel, Philippe, Series Editor, Guilyardi, Eric, Series Editor, Rabassa, Jorge, Series Editor, Horwood, Clive, Series Editor, Folguera, Andrés, editor, Contreras-Reyes, Eduardo, editor, Heredia, Nemesio, editor, Encinas, Alfonso, editor, B. Iannelli, Sofía, editor, Oliveros, Verónica, editor, M. Dávila, Federico, editor, Collo, Gilda, editor, Giambiagi, Laura, editor, Maksymowicz, Andrei, editor, Iglesia Llanos, María Paula, editor, Turienzo, Martín, editor, Naipauer, Maximiliano, editor, Orts, Darío, editor, D. Litvak, Vanesa, editor, Alvarez, Orlando, editor, and Arriagada, César, editor

Published
2018
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155. The Late Paleogene to Neogene Volcanic Arc in the Southern Central Andes (28°–37° S)

Author

Litvak, Vanesa D., Poma, Stella, Jones, Rosemary E., Fernández Paz, Lucía, Iannelli, Sofía B., Spagnuolo, Mauro, Kirstein, Linda A., Folguera, Andrés, Ramos, Victor A., Blondel, Philippe, Series Editor, Guilyardi, Eric, Series Editor, Rabassa, Jorge, Series Editor, Horwood, Clive, Series Editor, Folguera, Andrés, editor, Contreras-Reyes, Eduardo, editor, Heredia, Nemesio, editor, Encinas, Alfonso, editor, B. Iannelli, Sofía, editor, Oliveros, Verónica, editor, M. Dávila, Federico, editor, Collo, Gilda, editor, Giambiagi, Laura, editor, Maksymowicz, Andrei, editor, Iglesia Llanos, María Paula, editor, Turienzo, Martín, editor, Naipauer, Maximiliano, editor, Orts, Darío, editor, D. Litvak, Vanesa, editor, Alvarez, Orlando, editor, and Arriagada, César, editor

Published
2018
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156. The Structure of the Southern Central Andes (Chos Malal Fold and Thrust Belt)

Author

Turienzo, Martín, Sánchez, Natalia, Lebinson, Fernando, Dimieri, Luis, Blondel, Philippe, Series Editor, Guilyardi, Eric, Series Editor, Rabassa, Jorge, Series Editor, Horwood, Clive, Series Editor, Folguera, Andrés, editor, Contreras-Reyes, Eduardo, editor, Heredia, Nemesio, editor, Encinas, Alfonso, editor, B. Iannelli, Sofía, editor, Oliveros, Verónica, editor, M. Dávila, Federico, editor, Collo, Gilda, editor, Giambiagi, Laura, editor, Maksymowicz, Andrei, editor, Iglesia Llanos, María Paula, editor, Turienzo, Martín, editor, Naipauer, Maximiliano, editor, Orts, Darío, editor, D. Litvak, Vanesa, editor, Alvarez, Orlando, editor, and Arriagada, César, editor

Published
2018
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157. Mantle Influence on Andean and Pre-Andean Topography

Author

Dávila, Federico M., Lithgow-Bertelloni, Carolina, Martina, Federico, Ávila, Pilar, Nóbile, Julieta, Collo, Gilda, Ezpeleta, Miguel, Canelo, Horacio, Sánchez, Francisco, Blondel, Philippe, Series Editor, Guilyardi, Eric, Series Editor, Rabassa, Jorge, Series Editor, Horwood, Clive, Series Editor, Folguera, Andrés, editor, Contreras-Reyes, Eduardo, editor, Heredia, Nemesio, editor, Encinas, Alfonso, editor, B. Iannelli, Sofía, editor, Oliveros, Verónica, editor, M. Dávila, Federico, editor, Collo, Gilda, editor, Giambiagi, Laura, editor, Maksymowicz, Andrei, editor, Iglesia Llanos, María Paula, editor, Turienzo, Martín, editor, Naipauer, Maximiliano, editor, Orts, Darío, editor, D. Litvak, Vanesa, editor, Alvarez, Orlando, editor, and Arriagada, César, editor

Published
2018
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158. Paleogene Arc-Related Volcanism in the Southern Central Andes and North Patagonia (39°–41° S)

Author

Iannelli, Sofía B., Fernández Paz, Lucía, Litvak, Vanesa D., Jones, Rosemary E., Ramos, Miguel E., Folguera, Andrés, Ramos, Victor A., Blondel, Philippe, Series Editor, Guilyardi, Eric, Series Editor, Rabassa, Jorge, Series Editor, Horwood, Clive, Series Editor, Folguera, Andrés, editor, Contreras-Reyes, Eduardo, editor, Heredia, Nemesio, editor, Encinas, Alfonso, editor, B. Iannelli, Sofía, editor, Oliveros, Verónica, editor, M. Dávila, Federico, editor, Collo, Gilda, editor, Giambiagi, Laura, editor, Maksymowicz, Andrei, editor, Iglesia Llanos, María Paula, editor, Turienzo, Martín, editor, Naipauer, Maximiliano, editor, Orts, Darío, editor, D. Litvak, Vanesa, editor, Alvarez, Orlando, editor, and Arriagada, César, editor

Published
2018
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159. The Jurassic Paleogeography of South America from Paleomagnetic Data

Author

Iglesia Llanos, María Paula, Blondel, Philippe, Series Editor, Guilyardi, Eric, Series Editor, Rabassa, Jorge, Series Editor, Horwood, Clive, Series Editor, Folguera, Andrés, editor, Contreras-Reyes, Eduardo, editor, Heredia, Nemesio, editor, Encinas, Alfonso, editor, B. Iannelli, Sofía, editor, Oliveros, Verónica, editor, M. Dávila, Federico, editor, Collo, Gilda, editor, Giambiagi, Laura, editor, Maksymowicz, Andrei, editor, Iglesia Llanos, María Paula, editor, Turienzo, Martín, editor, Naipauer, Maximiliano, editor, Orts, Darío, editor, D. Litvak, Vanesa, editor, Alvarez, Orlando, editor, and Arriagada, César, editor

Published
2018
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160. Tectonic Rotations Along the Western Central Andes

Author

Arriagada, César, Blondel, Philippe, Series Editor, Guilyardi, Eric, Series Editor, Rabassa, Jorge, Series Editor, Horwood, Clive, Series Editor, Folguera, Andrés, editor, Contreras-Reyes, Eduardo, editor, Heredia, Nemesio, editor, Encinas, Alfonso, editor, B. Iannelli, Sofía, editor, Oliveros, Verónica, editor, M. Dávila, Federico, editor, Collo, Gilda, editor, Giambiagi, Laura, editor, Maksymowicz, Andrei, editor, Iglesia Llanos, María Paula, editor, Turienzo, Martín, editor, Naipauer, Maximiliano, editor, Orts, Darío, editor, D. Litvak, Vanesa, editor, Alvarez, Orlando, editor, and Arriagada, César, editor

Published
2018
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161. A Provenance Analysis from the Lower Jurassic Units of the Neuquén Basin. Volcanic Arc or Intraplate Magmatic Input?

Author

Naipauer, Maximiliano, García Morabito, Ezequiel, Manassero, Marcelo, Valencia, Victor V., Ramos, Victor A., Blondel, Philippe, Series Editor, Guilyardi, Eric, Series Editor, Rabassa, Jorge, Series Editor, Horwood, Clive, Series Editor, Folguera, Andrés, editor, Contreras-Reyes, Eduardo, editor, Heredia, Nemesio, editor, Encinas, Alfonso, editor, B. Iannelli, Sofía, editor, Oliveros, Verónica, editor, M. Dávila, Federico, editor, Collo, Gilda, editor, Giambiagi, Laura, editor, Maksymowicz, Andrei, editor, Iglesia Llanos, María Paula, editor, Turienzo, Martín, editor, Naipauer, Maximiliano, editor, Orts, Darío, editor, D. Litvak, Vanesa, editor, Alvarez, Orlando, editor, and Arriagada, César, editor

Published
2018
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162. Lower Jurassic to Early Paleogene Intraplate Contraction in Central Patagonia

Author

Navarrete, César R., Gianni, Guido M., Echaurren, Andrés, Folguera, Andrés, Blondel, Philippe, Series Editor, Guilyardi, Eric, Series Editor, Rabassa, Jorge, Series Editor, Horwood, Clive, Series Editor, Folguera, Andrés, editor, Contreras-Reyes, Eduardo, editor, Heredia, Nemesio, editor, Encinas, Alfonso, editor, B. Iannelli, Sofía, editor, Oliveros, Verónica, editor, M. Dávila, Federico, editor, Collo, Gilda, editor, Giambiagi, Laura, editor, Maksymowicz, Andrei, editor, Iglesia Llanos, María Paula, editor, Turienzo, Martín, editor, Naipauer, Maximiliano, editor, Orts, Darío, editor, D. Litvak, Vanesa, editor, Alvarez, Orlando, editor, and Arriagada, César, editor

Published
2018
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163. The Pre-Andean Phases of Construction of the Southern Andes Basement in Neoproterozoic–Paleozoic Times

Author

Heredia, Nemesio, García-Sansegundo, Joaquín, Gallastegui, Gloria, Farias, Pedro, Giacosa, Raúl, Hongn, Fernando, Tubía, José María, Alonso, Juan Juis, Busquets, Pere, Charrier, Reynaldo, Clariana, Pilar, Colombo, Ferrán, Cuesta, Andrés, Gallastegui, Jorge, Giambiagi, Laura, González-Menéndez, Luis, Limarino, Oscar, Martín-González, Fidel, Pedreira, David, Quintana, Luis, Rodríguez-Fernández, Luis Roberto, Rubio-Ordóñez, Álvaro, Seggiaro, Raúl, Serra-Varela, Samanta, Spalletti, Luis, Cardó, Raúl, Ramos, Victor A., Blondel, Philippe, Series Editor, Guilyardi, Eric, Series Editor, Rabassa, Jorge, Series Editor, Horwood, Clive, Series Editor, Folguera, Andrés, editor, Contreras-Reyes, Eduardo, editor, Heredia, Nemesio, editor, Encinas, Alfonso, editor, B. Iannelli, Sofía, editor, Oliveros, Verónica, editor, M. Dávila, Federico, editor, Collo, Gilda, editor, Giambiagi, Laura, editor, Maksymowicz, Andrei, editor, Iglesia Llanos, María Paula, editor, Turienzo, Martín, editor, Naipauer, Maximiliano, editor, Orts, Darío, editor, D. Litvak, Vanesa, editor, Alvarez, Orlando, editor, and Arriagada, César, editor

Published
2018
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164. Mechanisms and Episodes of Deformation Along the Chilean–Pampean Flat-Slab Subduction Segment of the Central Andes in Northern Chile

Author

Martínez, Fernando, Arriagada, César, Bascuñán, Sebastián, Blondel, Philippe, Series Editor, Guilyardi, Eric, Series Editor, Rabassa, Jorge, Series Editor, Horwood, Clive, Series Editor, Folguera, Andrés, editor, Contreras-Reyes, Eduardo, editor, Heredia, Nemesio, editor, Encinas, Alfonso, editor, B. Iannelli, Sofía, editor, Oliveros, Verónica, editor, M. Dávila, Federico, editor, Collo, Gilda, editor, Giambiagi, Laura, editor, Maksymowicz, Andrei, editor, Iglesia Llanos, María Paula, editor, Turienzo, Martín, editor, Naipauer, Maximiliano, editor, Orts, Darío, editor, D. Litvak, Vanesa, editor, Alvarez, Orlando, editor, and Arriagada, César, editor

Published
2018
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165. The Early Stages of the Magmatic Arc in the Southern Central Andes

Author

Oliveros, Verónica, González, Javiera, Espinoza Vargas, Mauricio, Vásquez, Paulina, Rossel, Pablo, Creixell, Christian, Sepúlveda, Fernando, Bastias, Francisco, Blondel, Philippe, Series Editor, Guilyardi, Eric, Series Editor, Rabassa, Jorge, Series Editor, Horwood, Clive, Series Editor, Folguera, Andrés, editor, Contreras-Reyes, Eduardo, editor, Heredia, Nemesio, editor, Encinas, Alfonso, editor, B. Iannelli, Sofía, editor, Oliveros, Verónica, editor, M. Dávila, Federico, editor, Collo, Gilda, editor, Giambiagi, Laura, editor, Maksymowicz, Andrei, editor, Iglesia Llanos, María Paula, editor, Turienzo, Martín, editor, Naipauer, Maximiliano, editor, Orts, Darío, editor, D. Litvak, Vanesa, editor, Alvarez, Orlando, editor, and Arriagada, César, editor

Published
2018
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166. The Famatinian Orogen Along the Protomargin of Western Gondwana: Evidence for a Nearly Continuous Ordovician Magmatic Arc Between Venezuela and Argentina

Author

Ramos, Victor A., Blondel, Philippe, Series Editor, Guilyardi, Eric, Series Editor, Rabassa, Jorge, Series Editor, Horwood, Clive, Series Editor, Folguera, Andrés, editor, Contreras-Reyes, Eduardo, editor, Heredia, Nemesio, editor, Encinas, Alfonso, editor, B. Iannelli, Sofía, editor, Oliveros, Verónica, editor, M. Dávila, Federico, editor, Collo, Gilda, editor, Giambiagi, Laura, editor, Maksymowicz, Andrei, editor, Iglesia Llanos, María Paula, editor, Turienzo, Martín, editor, Naipauer, Maximiliano, editor, Orts, Darío, editor, D. Litvak, Vanesa, editor, Alvarez, Orlando, editor, and Arriagada, César, editor

Published
2018
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167. The Peru-Chile Margin from Global Gravity Field Derivatives

Author

Álvarez, Orlando, Giménez, Mario, Klinger, Federico Lince, Folguera, Andrés, Braitenberg, Carla, Blondel, Philippe, Series Editor, Guilyardi, Eric, Series Editor, Rabassa, Jorge, Series Editor, Horwood, Clive, Series Editor, Folguera, Andrés, editor, Contreras-Reyes, Eduardo, editor, Heredia, Nemesio, editor, Encinas, Alfonso, editor, B. Iannelli, Sofía, editor, Oliveros, Verónica, editor, M. Dávila, Federico, editor, Collo, Gilda, editor, Giambiagi, Laura, editor, Maksymowicz, Andrei, editor, Iglesia Llanos, María Paula, editor, Turienzo, Martín, editor, Naipauer, Maximiliano, editor, Orts, Darío, editor, D. Litvak, Vanesa, editor, Alvarez, Orlando, editor, and Arriagada, César, editor

Published
2018
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168. Paleogeographic and Kinematic Constraints in the Tectonic Evolution of the Pre-Andean Basement Blocks

Author

Rapalini, Augusto E., Geuna, Silvana E., Franceschinis, Pablo R., Spagnuolo, Cecilia M., Blondel, Philippe, Series Editor, Guilyardi, Eric, Series Editor, Rabassa, Jorge, Series Editor, Horwood, Clive, Series Editor, Folguera, Andrés, editor, Contreras-Reyes, Eduardo, editor, Heredia, Nemesio, editor, Encinas, Alfonso, editor, B. Iannelli, Sofía, editor, Oliveros, Verónica, editor, M. Dávila, Federico, editor, Collo, Gilda, editor, Giambiagi, Laura, editor, Maksymowicz, Andrei, editor, Iglesia Llanos, María Paula, editor, Turienzo, Martín, editor, Naipauer, Maximiliano, editor, Orts, Darío, editor, D. Litvak, Vanesa, editor, Alvarez, Orlando, editor, and Arriagada, César, editor

Published
2018
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169. The Geometry of the Continental Wedge and Its Relation to the Rheology and Seismicity of the Chilean Interplate Boundary

Author

Maksymowicz, Andrei, Tassara, Andres, Blondel, Philippe, Series Editor, Guilyardi, Eric, Series Editor, Rabassa, Jorge, Series Editor, Horwood, Clive, Series Editor, Folguera, Andrés, editor, Contreras-Reyes, Eduardo, editor, Heredia, Nemesio, editor, Encinas, Alfonso, editor, B. Iannelli, Sofía, editor, Oliveros, Verónica, editor, M. Dávila, Federico, editor, Collo, Gilda, editor, Giambiagi, Laura, editor, Maksymowicz, Andrei, editor, Iglesia Llanos, María Paula, editor, Turienzo, Martín, editor, Naipauer, Maximiliano, editor, Orts, Darío, editor, D. Litvak, Vanesa, editor, Alvarez, Orlando, editor, and Arriagada, César, editor

Published
2018
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170. Northern Chile intermediate-depth earthquakes controlled by plate hydration.

Author

Cabrera, Leoncio, Ruiz, Sergio, Poli, Piero, Contreras-Reyes, Eduardo, Osses, Axel, and Mancini, Renzo

Subjects
*EARTHQUAKE aftershocks, *EARTHQUAKES, *EARTHQUAKE magnitude, *HYDRATION, *HEAT of hydration, *SUBDUCTION zones, *OCEANIC crust
Abstract

We investigate the variations of the seismic source properties and aftershock activity using kinematic inversions and template-matching for six large magnitude intermediate-depth earthquakes occurred in northern Chile. Results show similar rupture geometry and stress drop values between 7 and 30 MPa. Conversely, aftershock productivity systematically decreases for the deeper events within the slab. Particularly, there is a dramatic decrease in aftershock activity below the 400–450 °C isotherm depth, which separates high- and low-hydrated zones. The events exhibit tensional focal mechanisms at unexpected depths within the slab, suggesting a deepening of the neutral plane, where the extensional regimen reaches the 700–800 °C isotherm depth. We interpret the reduction of aftershocks in the lower part of the extensional regime as the absence of a hydrated-slab at those depths. Our finding highlights the role of the thermal structure and fluids in the subducting plate in controlling the intermediated-depth seismic activity and shed new light in their causative mechanism. [ABSTRACT FROM AUTHOR]

Published
2021
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171. Relationship Between Subduction Erosion and the Up‐Dip Limit of the 2014 Mw 8.1 Iquique Earthquake.

Author

Petersen, Florian, Lange, Dietrich, Ma, Bo, Grevemeyer, Ingo, Geersen, Jacob, Klaeschen, Dirk, Contreras‐Reyes, Eduardo, Barrientos, Sergio, Tréhu, Anne M., Vera, Emilio, and Kopp, Heidrun

Subjects
*EARTHQUAKE aftershocks, *SUBDUCTION zones, *EARTHQUAKES, *EROSION, *IMAGING systems in seismology, *SUBDUCTION, *OCEAN bottom, *SEISMOMETERS
Abstract

The aftershock distribution of the 2014 Mw 8.1 Iquique earthquake offshore northern Chile, identified from a long‐term deployment of ocean bottom seismometers installed eight months after the mainshock, in conjunction with seismic reflection imaging, provides insights into the processes regulating the updip limit of coseismic rupture propagation. Aftershocks updip of the mainshock hypocenter frequently occur in the upper plate and are associated with normal faults identified from seismic reflection data. We propose that aftershock seismicity near the plate boundary documents subduction erosion that removes mass from the base of the wedge and results in normal faulting in the upper plate. The combination of very little or no sediment accretion and subduction erosion over millions of years has resulted in a very weak and aseismic frontal wedge. Our observations thus link the shallow subduction zone seismicity to subduction erosion processes that control the evolution of the overriding plate. Plain Language Summary: To better understand the controls on shallow seismicity and subduction erosion following large subduction earthquakes, we use marine recordings of the Mw 8.1 2014 Iquique earthquake aftershocks and long‐offset multi‐channel seismic data. By comparing the aftershock locations and seismic imaging, we observe that most aftershocks occurred in the upper continental plate and abruptly stopped in the frontal forearc. The amplitude characteristics of upper‐crust reflections indicate a fractured and fluid‐filled outer forearc, which is associated with the absence of aftershocks. Large‐scale faulting, as evidenced by disrupted reflections in the seismic image, can be correlated to upper plate seismicity. We propose that the aftershocks updip of the main earthquake area reflect active subduction erosion processes. Key Points: We investigate structure and seismicity at the updip end of the 2014 Iquique earthquake rupture using amphibious seismic dataSeismicity updip of the 2014 Iquique earthquake occurs over a broad range likely interpreted to be related to the basal erosion processesCoseismic stress changes and aftershocks activate extensional faulting of the upper plate and subduction erosion [ABSTRACT FROM AUTHOR]

Published
2021
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172. Seismic structure and tectonics of the continental wedge overlying the source region of the Iquique Mw8.1 2014 earthquake.

Author

Reginato, Gabino, Vera, Emilio, Contreras-Reyes, Eduardo, Tréhu, Anne M., Maksymowicz, Andrei, Bello-González, Juan Pablo, and González, Felipe

Subjects
*FAULT zones, *EARTHQUAKE aftershocks, *SURFACE fault ruptures, *SEISMIC reflection method, *EARTHQUAKES, *SUBDUCTION zones, *CONTINENTAL crust, *IMAGING systems in seismology
Abstract

On April 1, 2014, a large earthquake (Mw = 8.1) ruptured the central part of a historic seismic gap in northern Chile. In order to study the relationship between the co-seismic rupture characteristics and the crustal structure of the subduction zone, we processed a trench-perpendicular seismic reflection profile acquired across the zone of maximum slip and generated a P-wave velocity model. The results show a frontal prism in the continental wedge characterized by low velocities that increase rapidly towards the shore and acted as a barrier for trench-ward propagation of aftershocks. Landward, a transition zone with increasing upper crust velocity (4–5 km/s) concentrates most of the aftershocks. In addition, a trench-ward dipping set of fault zones is observed along the continental wedge associated to the Iquique forearc basin formation (1.5 km thick at the depocenter on this profile). We identify three stratigraphic units within the basin. A landward tilt and thickness increase is detected in each stratigraphic unit, along with growth strata and domino structures, suggesting landward migration of syn -extensional deformation in response to basal subduction erosion. By extrapolating our results to the plate boundary and based on published focal mechanisms of intra-crustal seismicity, we find a strong spatial correlation between the Iquique basin and the highest slip area for the 2014 earthquake, suggesting long-term extensional deformation due to coseismic tensional stresses. • We present a seismic image for the epicentral region of the Iquique 2014 earthquake • Fault zones are spatially correlated with the highly fractured continental crust • long term deformation plays a role in the earthquake slip and aftershock distribution [ABSTRACT FROM AUTHOR]

Published
2020
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173. Geologic controls on up-dip and along-strike propagation of slip during subduction zone earthquakes from a high-resolution seismic reflection survey across the northern limit of slip during the 2010 Mw 8.8 Maule earthquake, offshore Chile.

Author

Tréhu, Anne M., Hass, Bridget, de Moor, Alexander, Maksymowicz, Andrei, Contreras-Reyes, Eduardo, Vera, Emilio, and Tryon, Michael D.

Subjects
*EARTHQUAKE zones, *SEISMIC surveys, *EARTHQUAKES, *LONG-Term Evolution (Telecommunications), *SUBDUCTION zones, *EARTHQUAKE resistant design, *PALEOSEISMOLOGY
Abstract

A grid of closely spaced, high-resolution multichannel seismic (MCS) reflection profiles was acquired in May 2012 over the outer accretionary prism up dip from the patch of greatest slip during the 2010 Mw 8.8 Maule earthquake (offshore Chile) to complement a natural-source seismic experiment designed to monitor the post-earthquake response of the outer accretionary prism. We describe the MCS data and discuss the implications for the response of the accretionary prism during the earthquake and for the long-term evolution of the margin. The most notable observation from the seismic reflection survey is a rapid north-to-south shift over a short distance from nearly total frontal accretion of the trench sediments to nearly total underthrusting of undeformed trench sediments that occurs near the northern edge of slip in the 2010 earthquake. Integrating our structural observations with other geological and geophysical observations, we conclude that sediment subduction beneath a shallow décollement is associated with propagation of slip to the trench during great earthquakes in this region. The lack of resolvable compressive deformation in the trench sediment along this segment of the margin indicates that the plate boundary here is very weak, which allowed the outer prism to shift seaward during the earthquake, driven by large slip down dip. The abrupt shift from sediment subduction to frontal accretion indicates a stepdown in the plate boundary fault, similar to the stepovers that commonly arrest slip propagation in strikeslip faults. We do not detect any variation along strike in the thickness or reflective character of the trench sediments adjacent to the change in deformation front structure. This change, however, is correlated with variations in the morphology and structure of the accretionary prism that extend as far as 40 km landward of the deformation front. We speculate that forearc structural heterogeneity is the result of subduction of an anomalously shallow or rough portion of plate that interacted with and deformed the overlying plate and is now deeply buried. This study highlights need for three-dimensional structural images to understand the interaction between geology and slip during subduction zone earthquakes. [ABSTRACT FROM AUTHOR]

Published
2019
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174. Impact of the Iquique Ridge on structure and deformation of the north Chilean subduction zone.

Author

Ma, Bo, Geersen, Jacob, Klaeschen, Dirk, Contreras-Reyes, Eduardo, Riedel, Michael, Xia, Yueyang, Tréhu, Anne M., Lange, Dietrich, and Kopp, Heidrun

Subjects
*SUBDUCTION, *SUBDUCTION zones, *WATER depth, *DEFORMATIONS (Mechanics), *SEAMOUNTS, *TOPOGRAPHY
Abstract

The subduction of seamounts and basement ridges affects the structure, morphology, and physical state of a convergent margin. To evaluate their impact on the seismo-tectonic setting of the subduction zone and the tectonic development of the lower subducting and upper overriding plate, it is essential to know the precise location of subducted topographic features under the marine forearc. Offshore Northern Chile, the Iquique Ridge represents a broad zone of complex and heterogeneous structure of variable width on the oceanic Nazca Plate, which complicates attempts to project it beneath the forearc of the Chilean subduction zone. Here we use a state-of-the-art seismic reflection data processing approach to map structures related to ridge subduction under the marine forearc with unprecedented accuracy and resolution and evaluate their impact on the deformation of both the plate boundary and the upper plate. We show that significant ridge-related topography is currently subducting south of 20.5 °S and that the combined effect of horst and graben subduction with subduction of Iquique ridge-related thickened and elevated crust causes an upward bulging of the entire upper plate from the plate interface up to the seafloor as well as the presence of kilometer-scale anticlinal structures observed in multibeam bathymetric data that are approximately aligned with horsts seaward of the trench. In the area affected by the subducting ridge, a frontal prism is absent, which may relate to frontal subduction erosion caused by the excess lower plate topography. In contrast farther towards the north, where only isolated seamounts subduct, a small frontal prism and a slope/apron sediment cover down to 3000 m water depth are found. [ABSTRACT FROM AUTHOR]

Published
2023
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175. The Peru-Chile Margin from Global Gravity Field Derivatives

Author

Andrés Folguera, Mario Giménez, Carla Braitenberg, Federico Lince Klinger, Orlando Álvarez, Andrés Folguera, Eduardo Contreras-Reyes, Nemesio Heredia, Alfonso Encinas, Sofía B. Iannelli, Verónica Oliveros, Federico M. Dávila, Gilda Collo, Laura Giambiagi, Andrei Maksymowicz, María Paula Iglesia Llanos, Martín Turienzo, Maximiliano Naipauer, Darío Orts, Vanesa D. Litvak, Orlando Alvarez, César Arriagada, Álvarez, Orlando, Giménez, Mario, Lince Klinger, Federico, Folguera, André, Braitenberg, Carla, Folguera Telichevsky, Andres, Contreras Reyes, Eduardo, Heredia, Nemesio, Encinas, Alfonso, Iannelli, Sofía, Oliveros Clavijo, Veronica Laura, Davila, Federico Miguel, Collo, Gilda, Giambiagi, Laura Beatriz, Maksymowicz, Andrei, Iglesia Llanos, Maria Paula, Turienzo, Martin Miguel, Naipauer, Maximiliano, Orts, Darío Leandro, Litvak, Vanesa Dafne, Alvarez Pontoriero, Orlando, and Arriagada, César

Subjects
GOCE, GRAVEDAD, geography, Geopotential, Megathrust earthquake, Accretionary wedge, geography.geographical_feature_category, Subduction, TERREMOTOS, Ciencias de la Tierra y relacionadas con el Medio Ambiente, Plate tectonics, Ridge, EGM2008, Megathrust earthquakes, Vertical gravity gradient, Trench, South American Plate, Geología, CIENCIAS NATURALES Y EXACTAS, Bouguer anomaly, Seismology, Geology
Abstract

Deformation along the 3,500 km subduction Pacific margin of the Peru-Chile trench is partially controlled by ocean bathymetric heterogeneities and sediments. Oceanic highs (e.g. ridges, fracture zones, plateaus) influence deformation in the fore-arc zone where collision occurs, and control turbiditic flow dispersal and consequently the amount of sediments accreted at the frontal accretionary prism and subduction channel, compartmentalizing the trench into segments linked to seismic segmentation. Recent satellite missions (CHAMP, GRACE and GOCE) have introduced an extraordinary improvement in the reconstruction of the global gravity field. Earth gravity field models, mainly derived from satellite measurements, reflect mass inhomogeneities of the earth. This chapter focuses on the determination of mass heterogeneities over the oceanic plate and their relation to general distribution of sediments over the Peru-Chilean margin, seismic segmentation along the margin, and the relationship between trench sediment thickness and the variable Andean orogenic volume, by means of a gravimetric analysis. Using the gravity potential model EGM2008 and satellite GOCE data we calculated two functionals of the geopotential: the Bouguer anomaly and the vertical gravity gradient, both corrected for the topographic effect. The vertical gravity gradient field is of special interest as it highlights main geological features, and allows unraveling unknown structures that are concealed by sediments. From these, different features can be clearly depicted such as the contact between the Pacific oceanic crust and the South American plate, the Nazca Ridge, the Juan Fernandez Ridge and the Chile Rise, among others. The segmentation between a filled trench south of Juan Fernandez Ridge, a partially filled trench to the north up to the Copiapo Ridge, and a completely starved trench north of this latitude is depicted. Finally, the relationship between gravity derived fields, high oceanic features and seismic segmentation is discussed for the last megathrust earthquakes that affected this subductive plate boundary. Fil: Alvarez Pontoriero, Orlando. Universidad Nacional de San Juan. Facultad de Ciencias Exactas, Físicas y Naturales. Instituto Geofísico Sismológico Volponi; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Gimenez, Mario Ernesto. Universidad Nacional de San Juan. Facultad de Ciencias Exactas, Físicas y Naturales. Instituto Geofísico Sismológico Volponi; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Lince Klinger, Federico Gustavo. Universidad Nacional de San Juan. Facultad de Ciencias Exactas, Físicas y Naturales. Instituto Geofísico Sismológico Volponi; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Folguera Telichevsky, Andres. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Estudios Andinos "Don Pablo Groeber". Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Estudios Andinos "Don Pablo Groeber"; Argentina Fil: Braitenberg, Carla. Universita di Trieste; Italia

Published
2018

176. A Provenance Analysis from the Lower Jurassic Units of the Neuquén Basin. Volcanic Arc or Intraplate Magmatic Input?

Author

Victor A. Ramos, Marcelo Jorge Manassero, Ezequiel Garcia Morabito, Maximiliano Naipauer, Victor A. Valencia, Folguera, Andrés, Contreras Reyes, Eduardo, Heredia, Nemesio, Encinas, Alfonso, Iannelli, Sofía, Oliveros, Veronica, Dávila, Federico, Collo, Gilda, Giambiagi, Laura Beatriz, Maksymowicz, Andrei, Iglesias Llanos, Paula, Turienzo, Martín, Naipauer, Maximiliano, Orts, Darío Leandro, Litvak, Vanesa Dafne, Alvarez Pontoriero, Orlando, and Arriagada Ortega, César Arturo

Subjects
geography, Provenance, geography.geographical_feature_category, Volcanic arc, Permian, Geochemistry, 010502 geochemistry & geophysics, 01 natural sciences, Ciencias de la Tierra y relacionadas con el Medio Ambiente, Volcanic rock, Petrography, Igneous rock, U-Pb DETRITAL AGES, CYO GROUP, Geochronology, Geología, 010503 geology, PROVENANCE, Geology, CIENCIAS NATURALES Y EXACTAS, 0105 earth and related environmental sciences, Zircon, Hf ISOTOPES
Abstract

A possible signal of the Jurassic Chon Aike Igneous Province within the early infill of the Neuquén Basin is recognized in our provenance analyses. We use a combination of detrital zircon geochronology and Lu-Hf isotope analysis, along with sandstone petrography descriptions to characterize the sediments source region in the Cuyo Group. The sandstone petrographic analysis confirms important contributions from volcanic sources of different compositions. U-Pb ages and Hf isotopes obtained in the analyzed zircons indicate a more complex configuration given by multiple igneous components. The variations in the provenance patterns allow us to make some observations about the paleogeographic evolution of the basin. At the base of the sequence, the sediments were derived from local sources composed of Permian basement and Upper Triassic volcanic rocks, whereas in the top, the zircons were supplied from Lower Jurassic volcanic rocks and Lower Paleozoic and Precambrian basements suggesting more distal and ancient sources. Low values of εHft (-15.5 to -0.7) analyzed in Permian and Triassic detrital zircons indicated an evolved source with strong crustal contribution. This data is in agreement with the negative values of εHft and εHft calculated in Permian and Triassic igneous rocks from the North Patagonian Massif. The Hft about -4 of the Jurassic detrital zircons indicated a crustal origin for the source rocks and are clearly compatible with the isotopic compositions of the Chon Aike Igneous Province. A volcanic source region compatible with the Andean arc is dismissed because the Jurassic arc has isotope characteristics of a mantle source. Fil: Naipauer, Maximiliano. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Estudios Andinos "Don Pablo Groeber". Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Estudios Andinos "Don Pablo Groeber"; Argentina Fil: Garcia Morabito, Ezequiel. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Estudios Andinos "Don Pablo Groeber". Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Estudios Andinos "Don Pablo Groeber"; Argentina Fil: Manassero, Marcelo Jorge. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Investigaciones Geológicas. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. Centro de Investigaciones Geológicas; Argentina Fil: Valencia, Victor. University of Washington; Estados Unidos Fil: Ramos, Victor Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Estudios Andinos "Don Pablo Groeber". Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Estudios Andinos "Don Pablo Groeber"; Argentina

Published
2018

177. Paleogene Arc-Related Volcanism in the Southern Central Andes and North Patagonia (39°–41° S)

Author

Sofía B. Iannelli, Rosemary E. Jones, Victor A. Ramos, Lucía Fernández Paz, Vanesa D. Litvak, Andrés Folguera, Miguel E. Ramos, Folguera Telichevsky, Andres, Contreras Reyes, Eduardo, Heredia Carballo, Nemesio, Encinas, Alfonso, Iannelli, Sofía, Oliveros, Verónica, Dávila, Federico M., Collo, Gilda, Giambiagi, Laura Beatriz, Maksymowicz, Andrei, Iglesia Llanos, María Paula, Turienzo, Martín, Naipauer, Maximiliano, Orts, Darío Leandro, Litvak, Vanesa Dafne, Álvarez, Orlando, and Arriagada Ortega, César Arturo

Subjects
GEOQUIMICA, geography, geography.geographical_feature_category, Volcanism, Ciencias de la Tierra y relacionadas con el Medio Ambiente, Arc (geometry), Volcanic rock, Paleontology, Tectonics, Volcano, ARCO, Magmatism, Geología, Farallon Plate, Paleogene, CIENCIAS NATURALES Y EXACTAS, Geology
Abstract

The influence of tectonic processes in evolution of magmatic suitesevaluated through their geochemical signature has always been a subject of debate.Late Paleocene arc volcanism in the Southern Central Andes, particularly in North Patagonia, can be used to infer a direct relationship between magmatic episodes and tectonic changes along the Andean margin. Eocene arc-related volcanism 11 (*44 Ma) in the North Patagonian Andes shows evidence for limited influence of 12 the subducting slab on the composition of arc magmas and they exhibit an alkaline tendency. By Oligocene times (*29 Ma), arc volcanic sequences in the Auca Pan 14 depocenter show predominantly arc-like geochemical signatures and have been 15 derived from a calc-alkaline source. However, a comparison with younger arc 16 sequences (

Published
2018

178. Neogene Growth of the Patagonian Andes

Author

César Navarrete, Andrés Echaurren, Patricia Martinez, Sofía B. Iannelli, Andrés Folguera, Alfonso Encinas, Francisco Ruiz, Lucía Fernández Paz, Guido M. Gianni, Mario Giménez, Vanesa D. Litvak, Darío Orts, Orlando Álvarez, Jonathan Tobal, Daniel Sellés, Lucas Fennell, Miguel E. Ramos, Folguera Telichevsky, Andres, Contreras-Reyes, Eduardo, Heredia, Nemesio, Encinas, Alfonso, Iannelli, Sofía, Oliveros, Verónica, Dávila, Federico M., Collo, Gilda, Giambiagi, Laura Beatriz, Maksymowicz, Andrei, Iglesia Llanos, María Paula, Turienzo, Martín, Naipauer, Maximiliano, Orts, Darío Leandro, Litvak, Vanesa Dafne, Álvarez, Orlando, and Arriagada, César

Subjects
geography, geography.geographical_feature_category, 010504 meteorology & atmospheric sciences, Subduction, Massif, Foreland basin, 010502 geochemistry & geophysics, Neogene, 01 natural sciences, Fold and thrust belt, Ciencias de la Tierra y relacionadas con el Medio Ambiente, Paleontology, Mountain formation, Magmatism, Patagonia, Geología, Accretion (geology), CIENCIAS NATURALES Y EXACTAS, Geology, 0105 earth and related environmental sciences
Abstract

After a Late Cretaceous to Paleocene stage of mountain building, the North Patagonian Andes were extensionally reactivated leading to a period of crustal attenuation. The result was the marine Traiguén Basin characterized by submarine volcanism and deep-marine sedimentation over a quasi-oceanic basement floor that spread between 27 and 22 Ma and closed by 20 Ma, age of syndeformational granitoids that cut the basin infill. As a result of basin closure, accretion of the Upper Triassic metamorphic Chonos Archipelago took place against the Chilean margin, overthrusting a stripe of high-density (mafic) rocks on the upper crust, traced by gravity data through the Chonos Archipiélago. After this, contractional deformation had a rapid propagation between 19 and 14.8 Ma rebuilding the Patagonian Andes and producing a wide broken foreland zone. This rapid advance of the deformational front, registered in synorogenic sedimentation, was accompanied at the latitudes of the North Patagonian Andes by an expansion of the arc magmatism between 19 and 14 Ma, suggesting a change in the subduction geometry at that time. Then a sudden retraction of the contractional activity took place around 13.5?11.3 Ma, accompanied by a retraction of magmatism and an extensional reactivation of the Andean zone that controlled retroarc volcanism up to 7.3?(4.6?) Ma. This particular evolution is explained by a shallow subduction regime in the northernmost Patagonian Andes, probably facilitated by the presence of the North Patagonian massif lithospheric anchor that would have blocked drag basal forces creating low-pressure conditions for slab shallowing. Contrastingly, to the south, the accretion of the Chonos Archipelago explains rapid propagation of the deformation across the retroarc zone. These processes occurred at the time of rather orthogonal to the margin convergence between Nazca and South American plates after a long period of high oblique convergence. Finally, convergence deceleration in the last 10 My could have led to extensional relaxation of the orogen. Fil: Folguera Telichevsky, Andres. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Estudios Andinos "Don Pablo Groeber". Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Estudios Andinos "Don Pablo Groeber"; Argentina Fil: Encinas, Alfonso. Universidad de Concepción; Chile Fil: Alvarez Pontoriero, Orlando. Universidad Nacional de San Juan. Facultad de Ciencias Exactas, Físicas y Naturales. Instituto Geofísico Sismológico Volponi; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Orts, Darío Leandro. Universidad Nacional de Río Negro. Facultad de Agronomía. Departamento de Ciencias Exactas, Naturales y de Ingeniería; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Gianni, Guido Martin. Universidad Nacional de San Juan. Facultad de Ciencias Exactas, Físicas y Naturales. Instituto Geofísico Sismológico Volponi; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Echaurren Gonzalez, Andres. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Estudios Andinos "Don Pablo Groeber". Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Estudios Andinos "Don Pablo Groeber"; Argentina Fil: Litvak, Vanesa Dafne. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Estudios Andinos "Don Pablo Groeber". Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Estudios Andinos "Don Pablo Groeber"; Argentina Fil: Navarrete, Cesar. Universidad Nacional de la Patagonia "San Juan Bosco". Facultad de Ciencias Naturales - Sede Comodoro. Departamento de Geología; Argentina Fil: Selles, Daniel. Universidad del Desarrollo; Chile Fil: Tobal, Jonathan Elías. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Estudios Andinos "Don Pablo Groeber". Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Estudios Andinos "Don Pablo Groeber"; Argentina Fil: Ramos, Miguel Esteban. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Estudios Andinos "Don Pablo Groeber". Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Estudios Andinos "Don Pablo Groeber"; Argentina Fil: Fennell, Lucas Martín. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Estudios Andinos "Don Pablo Groeber". Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Estudios Andinos "Don Pablo Groeber"; Argentina Fil: Fernández Paz, Lucía. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Estudios Andinos "Don Pablo Groeber". Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Estudios Andinos "Don Pablo Groeber"; Argentina Fil: Gimenez, Mario Ernesto. Universidad Nacional de San Juan. Facultad de Ciencias Exactas, Físicas y Naturales. Instituto Geofísico Sismológico Volponi; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Martinez, Patricia. Universidad Nacional de San Juan. Facultad de Ciencias Exactas, Físicas y Naturales. Instituto Geofísico Sismológico Volponi; Argentina Fil: Ruiz, Francisco. Universidad Nacional de San Juan. Facultad de Ciencias Exactas, Físicas y Naturales. Instituto Geofísico Sismológico Volponi; Argentina Fil: Iannelli, Sofía. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Estudios Andinos "Don Pablo Groeber". Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Estudios Andinos "Don Pablo Groeber"; Argentina

Published
2018

179. The late Oligocene-early Miocene marine transgression of Patagonia

Author

Francisca Tapia, Luis A. Buatois, José Ignacio Cuitiño, Darío Orts, Victor V. Valencia, Victor A. Ramos, Felipe Pérez, Patricio Zambrano, Verónica Oliveros, Lizet De Girolamo Del Mauro, Sven N. Nielsen, Alfonso Encinas, Pablo Bernabé, Kenneth L. Finger, Ricardo Riffo, Florencia Bechis, Andrés Folguera, Folguera Telichevsky, Andres, Contreras Reyes, Eduardo, Heredia, Nemesio, Encinas, Alfonso, Iannelli, Sofía, Oliveros, Verónica, Davila, Federico Miguel, Collo, Gilda, Giambiagi, Laura Beatriz, Maksymowicz, Andrei, Iglesia Llanos, Maria Paula, Turienzo, Martin Miguel, Naipauer, Maximiliano, Orts, Darío Leandro, Litvak, Vanesa Dafne, Alvarez Pontoriero, Orlando, and Arriagada, César

Subjects
010506 paleontology, Fluvial, 010502 geochemistry & geophysics, OLIGOCENE–MIOCENE TRANSGRESSION, Geociencias multidisciplinaria, 01 natural sciences, Deposition (geology), Ciencias de la Tierra y relacionadas con el Medio Ambiente, Paleontology, Tectonics, PATAGONIA, PATAGONIAN ANDES, Stratigraphy, Geochronology, Period (geology), OROGENESIS, Cenozoic, Geology, EXTENSION, CIENCIAS NATURALES Y EXACTAS, 0105 earth and related environmental sciences, Marine transgression
Abstract

The most important Cenozoic marine transgression in Patagonia occurred during the late Oligocene–early Miocene when marine waters of Pacific and Atlantic origin flooded most of southern South America including the present Patagonian Andes between ~41° and 47° S. The age, correlation, and tectonic setting of the different marine formations deposited during this period are debated. However, recent studies based principally on U–Pb geochronology and Sr isotope stratigraphy, indicate that all of these units had accumulated during the late Oligocene–early Miocene. The marine transgression flooded a vast part of southern South America and, according to paleontological data, probably allowed for the first time in the history of this area a transient connection between the Pacific and Atlantic oceans. Marine deposition started in the late Oligocene–earliest Miocene (~26–23 Ma) and was probably caused by a regional event of extension related to major plate reorganization in the Southeast Pacific. Progressive extension and crustal thinning allowed a generalized marine flooding of Patagonia that reached its maximum extension at ~20 Ma. It was followed by a phase of compressive tectonics that started around 19–16 Ma and led to the growth of the Patagonian Andes. The youngest (~19–15 Ma) marine deposits that accumulated in the eastern Andean Cordillera and the extra-Andean regions are coeval with fluvial synorogenic deposits and probably had accumulated under a compressive regime. Fil: Encinas, Alfonso. Universidad de Concepción; Chile Fil: Folguera Telichevsky, Andres. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Estudios Andinos "Don Pablo Groeber". Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Estudios Andinos "Don Pablo Groeber"; Argentina Fil: Bechis, Florencia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte. Instituto de Investigaciones en Diversidad Cultural y Procesos de Cambio. Universidad Nacional de Río Negro. Instituto de Investigaciones en Diversidad Cultural y Procesos de Cambio; Argentina Fil: Finger, Kennet. University of California; Estados Unidos Fil: Zambrano, Patricio. Universidad Andrés Bello; Chile Fil: Pérez, Andrés Felipe. Universidad de Concepción; Chile Fil: Bernabé, Pablo. Universidad de Concepción; Chile Fil: Tapia, Francisca. Universidad de Concepción; Chile Fil: Riffo, Ricardo. Universidad de Concepción; Chile Fil: Buatois, Luis Alberto. University of Saskatchewan; Canadá Fil: Orts, Darío Leandro. Universidad Nacional de Río Negro. Sede Alto Valle. Instituto de Investigaciones en Paleobiología y Geología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Nielsen, Sven Nikolaus. Universidad Austral de Chile. Instituto de Ciencias de la Tierra; Chile Fil: Valencia, Víctor V.. Washington State University; Estados Unidos Fil: Cuitiño, José Ignacio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico. Instituto Patagónico de Geología y Paleontología; Argentina Fil: Oliveros, Verónica. Universidad de Concepción; Chile Fil: De Girolamo Del Mauro, Lizet. Universidad de Concepción; Chile Fil: Ramos, Victor Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Estudios Andinos "Don Pablo Groeber". Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Estudios Andinos "Don Pablo Groeber"; Argentina

Published
2018

180. The Famatinian orogen along the protomargin of Western Gondwana: Evidence for a nearly continuous Ordovician magmatic arc between Venezuela and Argentina

Author

Ramos, Victor Alberto, Folguera Telichevsky, Andres, Contreras Reyes, Eduardo, Heredia, Nemesio, Encinas, Alfonso, Iannelli, Sofía, Oliveros, Verónica, Dávila, Federico M., Collo, Gilda, Giambiagi, Laura Beatriz, Maksymowicz, Andrei, Iglesia Llanos, Maria Paula, Turienzo, Martin Miguel, Naipauer, Maximiliano, Orts, Darío Leandro, Litvak, Vanesa Dafne, Alvarez Pontoriero, Orlando, and Arriagada, César

Subjects
TECTONICS, Geología, ANDES, MAGMATIC ARC, CIENCIAS NATURALES Y EXACTAS, ORDOVICIAN, Ciencias de la Tierra y relacionadas con el Medio Ambiente
Abstract

The continental protomargin of Western Gondwana in South America records an important Early-Middle Ordovician magmatic activity associated with the development of the Famatinian orogen. Almost the entire margin has evidence of a magmatic arc preserved as orthogneisses in the high grade metamorphic domains up to volcanic rocks of the same age interfingered with sedimentary facies. These subduction related calcalkaline rocks have new UPb zircon dates that show striking similar ages bracketed between 490 and 460 Ma. The different domains along the continental margin are compared taking the western Sierras Pampeanas as the type locality, showing an alternation among high grade metamorphic – greenschist facies – sedimentary facies. There are three deeply-exhumed segments preserved as orthogneisses in high grade amphibolite facies, the Sierras Pampeanas, the Marañón and the Santander-Mérida domains. These domains are flanked by greenschist facies such as the Quetame in Colombia, the Vilcabamba in Perú, and the Puna Eruptive Belt in northern Argentina. Some segments are characterized by sedimentary facies as the Altiplano domain of Bolivia and the Olmos-Loja domain between Perú and Ecuador. The location and metamorphic grade are controlled by the amount of shortening and uplift, responsible for the different crustal levels exposed, as a consequence of the characteristics of the distinct terranes that collided against the continental margin. As a final remark, the time span of the Famatinian episode when globally compared has a widespread development in Laurentia, Baltica, and Australia, as a consequence of a period of high mobility of the plates during Early-Middle Ordovician times. Fil: Ramos, Victor Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Estudios Andinos "Don Pablo Groeber". Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Estudios Andinos "Don Pablo Groeber"; Argentina

Published
2018

181. Cretaceous Orogeny and Marine Transgression in the Southern Central and Northern Patagonian Andes: Aftermath of a Large-Scale Flat-Subduction Event?

Author

Lucas Fennell, Guido M. Gianni, Federico M. Dávila, Paulo Quezada, Andrés Folguera, Mario Giménez, César Navarrete, Jonathan Tobal, Andrés Echaurren, Folguera Telichevsky, Andres, Contreras Reyes, Eduardo, Heredia, Nemesio, Encinas, Alfonso, Iannelli, Sofía, Oliveros, Verónica, Dávila, Federico M., Collo, Gilda, Giambiagi, Laura Beatriz, Maksymowicz, Andrei, Iglesia Llanos, María Paula, Turienzo, Martin Miguel, Naipauer, Maximiliano, Orts, Darío Leandro, Litvak, Vanesa Dafne, Álvarez, Orlando, and Arriagada Ortega, César Arturo

Subjects
geography, Fold and Thrust Belt, geography.geographical_feature_category, 010504 meteorology & atmospheric sciences, Subduction, Andes, Orogeny, Fold (geology), Foreland Basin, 010502 geochemistry & geophysics, 01 natural sciences, Cretaceous, Ciencias de la Tierra y relacionadas con el Medio Ambiente, Paleontology, Broken Foreland Basin, Back-arc basin, Fold and thrust belt, Geología, Dynamic Subsidence, Flat-Slab, Foreland basin, CIENCIAS NATURALES Y EXACTAS, Geology, 0105 earth and related environmental sciences, Marine transgression
Abstract

This review synthesizes the tectonomagmatic evolution of the southern Central andNorthern Patagonian Andes between 35°30?S to 48°S with the aim to spotlight earlycontractional phases on Andean orogenic building and to analyze their potential drivingprocesses. We examine early tectonic stages of the different fold and thrust belts that composethis Andean segment. Additionally, we study the magmatic arc behavior from a regionalperspective as an indicator of potential past subduction configurations during critical tectonicstages of orogenic construction. This revision proposes the existence of a continuous large-scaleflat subduction with a similar size to the present-largest flat-slab setting on earth. This particularprocess would have initiated diachronically in late Early Cretaceous times and achieved fulldevelopment in Late Cretaceous to earliest Paleocene, constructing a series of fold - thrust beltson the retro-arc zone from 35°30?S to 48°S. Furthermore, dynamic subsidence focused at theedges of the slab flattening before re-steepening beneath the foreland zone may explain suddenpaleogeographic changes in Maastrichtian-Danian times previously linked to continental tiltingand orogenic loading during a high sea level global stage. Fil: Gianni, Guido Martin. Universidad Nacional de San Juan. Facultad de Ciencias Exactas, Físicas y Naturales. Instituto Geofísico Sismológico Volponi; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Echaurren, Andrés. Universidad de Buenos Aires; Argentina Fil: Fennell, Lucas Martín. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Estudios Andinos "Don Pablo Groeber". Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Estudios Andinos "Don Pablo Groeber"; Argentina Fil: Navarrete Granzotto, César Rodrigo. Universidad Nacional de la Patagonia San Juan Bosco; Argentina Fil: Quezada, Paulo. Universidad Andrés Bello; Chile Fil: Tobal, Jonathan Elías. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Estudios Andinos "Don Pablo Groeber". Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Estudios Andinos "Don Pablo Groeber"; Argentina Fil: Giménez, Mario. Universidad Nacional de San Juan. Facultad de Ciencias Exactas, Físicas y Naturales. Instituto Geofísico Sismológico Volponi; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Dávila, Federico M.. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Centro de Investigaciones en Ciencias de la Tierra. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Centro de Investigaciones en Ciencias de la Tierra; Argentina Fil: Folguera Telichevsky, Andres. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Estudios Andinos "Don Pablo Groeber". Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Estudios Andinos "Don Pablo Groeber"; Argentina

Published
2018

182. The Structure of the Southern Central Andes (Chos Malal Fold and Thrust Belt)

Author

Natalia Paola Sánchez, Fernando Oscar Lebinson, Luis Vicente Dimieri, Martin Miguel Turienzo, Folguera Telichevsky, Andres, Contreras Reyes, Eduardo, Heredia, Nemesio, Encinas Bachiller, Andrés Marcos, Iannelli, Sofía, Oliveros Villamil, Matilde, Davila, Federico Miguel, Collo, Gilda, Giambiagi, Laura Beatriz, Maksymowicz, Andrei, Iglesia Llanos, Maria Paula, Turienzo, Martin Miguel, Naipauer, Maximiliano, Orts, Darío Leandro, Litvak, Vanesa Dafne, Alvarez Pontoriero, Orlando, and Arriagada, Cesar

Subjects
geography, geography.geographical_feature_category, Andean orogeny, 010504 meteorology & atmospheric sciences, Inversion (geology), THICK SKINNED STRUCTURES, Anticline, NEUQUÉN BASIN, Deformation (meteorology), 010502 geochemistry & geophysics, 01 natural sciences, BALANCED CROSS SECTIONS, Ciencias de la Tierra y relacionadas con el Medio Ambiente, Tectonics, Basement (geology), Monocline, Fold and thrust belt, Geología, Petrology, Geology, CIENCIAS NATURALES Y EXACTAS, 0105 earth and related environmental sciences
Abstract

The Chos Malal fold and thrust belt, formed during the Andean orogeny, is characterized by the involvement of both the Paleozoic basement and Mesozoic strata of the Neuquén Basin into the deformation. Two detailed structural cross sections, built based on previous field mapping, new subsurface interpretations, and seismic and borehole data, allow characterizing the structural style of this orogenic belt. A close interaction between large thick-skinned structures (first order) and complex thin-skinned structures (second, third, and fourth order), related to the presence of multiple detachments in the sedimentary cover, is recognized. The largest thrusts form basement-involved duplex structures, with a lower detachment located at a depth of about 12–14 km and an upper detachment in the Jurassic evaporites of the Auquilco Formation. Displacement transmitted by these basement sheets in the inner zone of the Chos Malal fold and thrust belt produces a wide region of thin-skinned deformation, which contains second-order fault-bend folds that transfer deformation to the overlying Agrio Formation shales (Early Cretaceous) giving rise to third-order folds and thrusts involving this unit. In the outer zone, the basement-involved thrusts have less displacement and form monoclines and a complex thin-skinned deformation restricted to the deformation front, possibly caused by buttressing effect exerted by the overlying Miocene volcanic sequences. This impediment in forward deformation leads to an important out-of-sequence faulting, whose displacement is compensated by a passive-roof backthrust along the Cretaceous evaporites of the Bajada del Agrio Group forming a triangle zone. Second-order anticlines under this triangle zone, where the seismic data are of low quality, constitute important hydrocarbon oil fields such as El Porton and Filo Morado. Understanding the close relationship between the structures of different order cropping out in the inner zone of the Chos Malal fold and thrust belt is important to interpret the subsurface structures forming hydrocarbon oil fields in the outer zone as well as to identify other complex structures that may lead to new exploration opportunities. Restitution of the structural cross sections allowed calculating a tectonic shortening for this region in the order of 22–25 km (16–18%), higher than estimated by previous authors who generally simplified the thin-skinned deformation and considered the tectonic inversion of normal faults as the main mechanism of deformation in this orogen. Fil: Turienzo, Martin Miguel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto Geológico del Sur. Universidad Nacional del Sur. Departamento de Geología. Instituto Geológico del Sur; Argentina Fil: Sánchez, Natalia Paola. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto Geológico del Sur. Universidad Nacional del Sur. Departamento de Geología. Instituto Geológico del Sur; Argentina Fil: Lebinson, Fernando Oscar. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto Geológico del Sur. Universidad Nacional del Sur. Departamento de Geología. Instituto Geológico del Sur; Argentina Fil: Dimieri, Luis Vicente. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto Geológico del Sur. Universidad Nacional del Sur. Departamento de Geología. Instituto Geológico del Sur; Argentina

Published
2018

183. Lower Jurassic to Early Paleogene Intraplate Contraction in Central Patagonia

Author

Andrés Folguera, Andrés Echaurren, Guido M. Gianni, César Navarrete, Folguera Telichevsky, Andres, Contreras Reyes, Eduardo, Heredia Carballo, Nemesio, Encinas, Alfonso, Iannelli, Sofía, Oliveros, Verónica, Dávila, Federico M., Collo, Gilda, Giambiagi, Laura Beatriz, Maksymowicz, Andrei, Iglesia Llanos, María Paula, Turienzo, Martín, Naipauer, Maximiliano, Orts, Darío Leandro, Litvak, Vanesa Dafne, Álvarez, Orlando, and Arriagada Ortega, César Arturo

Subjects
Andean orogeny, 010504 meteorology & atmospheric sciences, Inversion (geology), Jurassic, Tectonic, 010502 geochemistry & geophysics, 01 natural sciences, Cretaceous, Ciencias de la Tierra y relacionadas con el Medio Ambiente, Paleontology, Gondwana, Continental drift, Ridge push, Patagonia, Intraplate earthquake, Geología, Paleogene, CIENCIAS NATURALES Y EXACTAS, Geology, 0105 earth and related environmental sciences
Abstract

Breakup and dispersion stages of Gondwana were ruled by crustal extension. In Patagonia, this regime was associated with the opening of extensional basins from the Jurassic onwards, a process that was interrupted by the Andean orogeny. New data generated from the hydrocarbon exploration allowed identifying Jurassic to Eocene contractional deformations, previously not registered in central Patagonia. We summarize in this chapter evidence for five compressional events intercalated with the extensional regime that affected central Patagonia from the Early Jurassic to the Paleogene. These events, denominated ?C1?, ?C2?, ?C3?, ?C4? and ?C5? acted diachronicronously producing tectonic inversion of the Jurassic-Cretaceous depocenters. The first three contractional pulses occurred during the Jurassic while the two remaining were late Lower Cretaceous and early Paleogene. The origin of this compressive activity would be linked to different processes that comprehend from thermal weakening of the crust produced by expansion of the thermal anomaly of Karoo in Mid to Late Jurassic times; the southwards continental drift since the Early Jurassic; the ridge-push generated by the opening of Wedell Sea since Mid Jurassic times; and two mid ocean ridge collisions during the Cretaceous. Fil: Navarrete Granzotto, César Rodrigo. Universidad Nacional de la Patagonia "San Juan Bosco"; Argentina Fil: Gianni, Guido Martin. Universidad Nacional de San Juan. Facultad de Ciencias Exactas, Físicas y Naturales. Instituto Geofísico Sismológico Volponi; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Echaurren Gonzalez, Andres. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Estudios Andinos "Don Pablo Groeber". Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Estudios Andinos "Don Pablo Groeber"; Argentina Fil: Folguera Telichevsky, Andres. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Estudios Andinos "Don Pablo Groeber". Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Estudios Andinos "Don Pablo Groeber"; Argentina

Published
2018

184. Thick, strong sediment subduction along south-central Chile and its role in great earthquakes.

Author

Olsen, Kelly M., Bangs, Nathan L., Tréhu, Anne M., Han, Shuoshuo, Arnulf, Adrien, and Contreras-Reyes, Eduardo

Subjects
*SEDIMENTS, *SEISMOGRAMS, *SEISMIC surveys, *EARTHQUAKES, *SEDIMENT analysis, *SUBDUCTION zones, *SUBDUCTION
Abstract

• New seismic images off south-central Chile acquired with a 15-km-long receiver array. • The decollement is unusually shallow at the deformation front along S. central Chile. • Shallow sediment subduction along south-central Chile is among the world's thickest. • P-wave velocities imply S. central Chile trench sediments are well-drained and strong. • Thick, strong sediment subduction may enhance interplate coupling and earthquake size. The south-central Chile margin experienced the largest and sixth largest earthquakes ever recorded - the 1960 Mw 9.5 Valdivia and 2010 Mw 8.8 Maule megathrust earthquakes, respectively. In early 2017, we conducted a seismic survey along 1,000 km of south-central Chile to image these rupture zones using a 15.15-km-long multi-channel seismic streamer. We processed these data using pre-stack depth migration, which provides the best look at the shallow part of the south-central Chile margin to date. Relative to other sediment-dominated subduction zones, where sediment is typically accreted at the toe, an unusually large percentage of the thick trench sediments are consistently subducted beneath the slope with little thrust faulting or deformation. Analysis of the sediment P-wave velocities and structure in the trench and outer wedge leads us to conclude that most of south-central Chile contains well-drained, strong sediments. An exception in the vicinity of the subducting Mocha Fracture Zone (MFZ) has trench sediments that appear to experience localized delayed compaction, thus lowering their strength and allowing the development of protothrusts, similar to what is seen in other accretionary subduction zones. The very shallow décollement along the south-central Chile allows more sediment to pass beneath the lower slope than almost all other subduction zone, many of which have much thicker trench sections. We conclude that subduction of the strong, well-drained, thick sediment layer beneath the lower slope is typical for nearly all of the south-central Chile. Comparison to other thick-sedimented subduction zones worldwide reveals that the subduction of such a large fraction of the trench sediment is particularly unusual. This strong, thick, subducting sediment is likely a determining factor for developing a smooth plate interface located well above the subducted crust topography that ultimately becomes a broad megathrust with high, homogeneous frictional properties, and generates particularly large earthquakes along the south central Chile margin. [ABSTRACT FROM AUTHOR]

Published
2020
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185. The structure of the 2014 Mw 8.1 Iquique earthquake revealed by offshore observations.

Author

Petersen, Florian, Lange, Dietrich, Grevemeyer, Ingo, Kopp, Heidrun, Contreras-Reyes, Eduardo, Barrientos, Sergio, and Tréhu, Anne M.

Subjects
*EARTHQUAKES, *OFFSHORE structures, *OCEAN bottom, *SEISMOMETERS, *SENDAI Earthquake, Japan, 2011
Abstract

On April 2014 the Iquique Mw 8.1 earthquake ruptured the interpolate contact between the oceanic Nazca and continental South American plates offshore northern Chile between 19.5°S to 21°S in April 2014. This earthquake did not fully release the strain accumulated since the last great megathrust (Mw 8.8) in 1877 and had left an unbroken segment in the south. From December 2014 to November 2016, we deployed an offshore network of 15 Ocean Bottom Seismometers (OBS) that covered the rupture area and the unbroken southern segment using the Chilean Navy ship OPV Toro and R/V Sonne. That data set is supplemented by five weeks of data from 67 OBS installed for a controlled source seismic experiment during cruise MGL1610 of the R/V Marcus Langseth in late 2016. Data acquired onshore by stations from of the IPOC (Integrated Plate Boundary Observatory Chile) and CSN (Chilean Seismological Service) networks are also included.We present first results of this ongoing project, which include double-difference hypocenter relocations based on waveform cross-correlation. Most of the seismicity occurs between 19.5 and 21°S up-dip of the patch of maximum coseismic slip during the 2014 earthquake, while the seismicity in seismogenic depths is highly concentrated forming well-defined clusters. The observed seismicity provides constraints on the structure of the marine forearc and enables us to relate the seismicity distribution to the background seismicity, seafloor morphology, and regional tectonics. [ABSTRACT FROM AUTHOR]

Published
2019

186. Modelamiento flexural tridimensiónal de la litosfera oceanica de nazca frente a las costas del norte (14°s-23°s) y centro de Chile (32°s-34° s)

Author

MANRIQUEZ REVECO, PAULA MARCELA, CONTRERAS REYES, EDUARDO ELISEO, and UNIVERSIDAD DE CHILE/FACULTAD DE CIENCIAS FISICAS Y MATEMATICAS/DEPARTAMENTO DE GEOFISICA

Abstract

MAGISTER EN CIENCIAS, MENCION GEOFISICA http://sial.fondecyt.cl/index.php/investigador/f4_tesis_memorias/descarga/11228764/1110290/0/60295/1/ FONDECYT FONDECYT

Published
2012

187. Megathrust reflectivity reveals the updip limit of the 2014 Iquique earthquake rupture.

Author

Ma B, Geersen J, Lange D, Klaeschen D, Grevemeyer I, Contreras-Reyes E, Petersen F, Riedel M, Xia Y, Tréhu AM, and Kopp H

Abstract

The updip limit of seismic rupture during a megathrust earthquake exerts a major control on the size of the resulting tsunami. Offshore Northern Chile, the 2014 Mw 8.1 Iquique earthquake ruptured the plate boundary between 19.5° and 21°S. Rupture terminated under the mid-continental slope and did not propagate updip to the trench. Here, we use state-of-the-art seismic reflection data to investigate the tectonic setting associated with the apparent updip arrest of rupture propagation at 15 km depth during the Iquique earthquake. We document a spatial correspondence between the rupture area and the seismic reflectivity of the plate boundary. North and updip of the rupture area, a coherent, highly reflective plate boundary indicates excess fluid pressure, which may prevent the accumulation of elastic strain. In contrast, the rupture area is characterized by the absence of plate boundary reflectivity, which suggests low fluid pressure that results in stress accumulation and thus controls the extent of earthquake rupture. Generalizing these results, seismic reflection data can provide insights into the physical state of the shallow plate boundary and help to assess the potential for future shallow rupture in the absence of direct measurements of interplate deformation from most outermost forearc slopes., (© 2022. The Author(s).)

Published
2022
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188. Gas origin linked to paleo BSR.

Author

de la Cruz Vargas-Cordero I, Villar-Muñoz L, Tinivella U, Giustiniani M, Bangs N, Bento JP, and Contreras-Reyes E

Abstract

The Central-South Chile margin is an excellent site to address the changes in the gas hydrate system since the last deglaciation associated with tectonic uplift and great earthquakes. However, the dynamic of the gas hydrate/free gas system along south central Chile is currently not well understood. From geophysical data and modeling analyses, we evaluate gas hydrate/free gas concentrations along a seismic line, derive geothermal gradients, and model past positions of the Bottom Simulating Reflector (BSR; until 13,000 years BP). The results reveal high hydrate/free gas concentrations and local geothermal gradient anomalies related to fluid migration through faults linked to seafloor mud volcanoes. The BSR-derived geothermal gradient, the base of free gas layers, BSR distribution and models of the paleo-BSR form a basis to evaluate the origin of the gas. If paleo-BSR coincides with the base of the free gas, the gas presence can be related to the gas hydrate dissociation due to climate change and geological evolution. Only if the base of free gas reflector is deeper than the paleo-BSR, a deeper gas supply can be invoked., (© 2021. The Author(s).)

Published
2021
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189. A cold seep triggered by a hot ridge subduction.

Author

Villar-Muñoz L, Kinoshita M, Bento JP, Vargas-Cordero I, Contreras-Reyes E, Tinivella U, Giustiniani M, Abe N, Anma R, Orihashi Y, Iwamori H, Nishikawa T, Veloso EA, and Haraguchi S

Abstract

The Chile Triple Junction, where the hot active spreading centre of the Chile Rise system subducts beneath the South American plate, offers a unique opportunity to understand the influence of the anomalous thermal regime on an otherwise cold continental margin. Integrated analysis of various geophysical and geological datasets, such as bathymetry, heat flow measured directly by thermal probes and calculated from gas hydrate distribution limits, thermal conductivities, and piston cores, have improved the knowledge about the hydrogeological system. In addition, rock dredging has evidenced the volcanism associated with ridge subduction. Here, we argue that the localized high heat flow over the toe of the accretionary prism results from fluid advection promoted by pressure-driven discharge (i.e., dewatering/discharge caused by horizontal compression of accreted sediments) as reported previously. However, by computing the new heat flow values with legacy data in the study area, we raise the assumption that these anomalous heat flow values are also promoted by the eastern flank of the currently subducting Chile Rise. Part of the rift axis is located just below the toe of the wedge, where active deformation and vigorous fluid advection are most intense, enhanced by the proximity of the young volcanic chain. Our results provide valuable information to current and future studies related to hydrothermal circulation, seismicity, volcanism, gas hydrate stability, and fluid venting in this natural laboratory., (© 2021. The Author(s).)

Published
2021
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