Proceedings of the 12th International INQUA meeting on paleoseismology, active tectonic and archaeoseismology

132 PATA Days 2024 1 2 T H I N T E R N AT I O N A L I N Q U A M E E T I N G O N PA L E O S E I S M O L O G Y , A C T I V E T E C T O N I C S A N D A R C H A E O S E I S M O L O G Y ( PATA ) , O C T O B E R 6 T H - 1 1 T H , 2 0 2 4 , L O S A N D E S , C H I L E K E Y W O R D S Analog modeling, syntectonic sedimentation, propagation, Quaternary activity. (1) Departamento de Geología, Universidad de Chile, Plaza Ercilla 803, 8370450 Santiago, Chile. (2) Departamento de Ingeniería en Minas, Facultad de Ingeniería, Universidad de Santiago, Chile. *Email: pamela.jara@usach.cl Javiera Cortés (1) Luisa Pinto (1) Pamela Jara (2) * EFFECTS OF SYNTECTONIC SEDIMENTARY LOADING ON THE EVOLUTION OF AN OROGENIC BORDER: ANALOG MODELING APPLIED TO THE QUATERNARY ACTIVITY OF THE POCURO FAULT SYSTEM CHILEAN ANDES (~32 . 5°S) A B S T R A C T A landscape mountain transition is notable on the western border of the Andes at 32°-33°S. North, transverse valleys connect the Principal with Coastal Cordilleras; south, the Los Andes- San Felipe Depression acts as a geomorphological division. This configuration results in a marked sedimentation difference, high to the south and notably scarce to the north of 32°30'S. Interaction with the Andean orogeny formation front, particularly the Pocuro Fault Zone (PFZ), reveals variable Quaternary tectonic activity influenced by sedimentary deposits. With analog models, we simulate this setting, showing a strong correlation between the syntectonic sedimentation rate and the structural system geometry. Higher sedimentation rates limit structural propagation towards the deformational front, producing less propagation of faults. The wider western propagation of recent faults of the PFZ could be attributed to lower syntectonic sedimentation, thus resulting in a westernmost deformational front north of the Los Andes-San Felipe Depression due to sediment scarcity. I N T R O D U C T I O N The AndeanWestern Cordillera between 32°S and 33°S exhibits a notable landscape transition (Fig. 1). In the northern part of this belt, transverse valleys connecting the Andes Cordillera with the Coastal Cordillera are observed. However, in the southern part, where the Los Andes-San Felipe Depression is found, a sedimentary basin acts as a geomorphological division between both mountain ranges. This phenomenon results in a marked difference between