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

K E Y R E S U LT S In the La Rinconada area, we found evidence of drainage disequilibrium, with several scattered knickpoints associated with high Ksn values. These points are mainly concentrated in the hanging wall of the La Rinconada fault, where Paleozoic rocks outcrop. This phenomenon could be linked to differences in erosion and uplift rates, highlighting the need for detailed field controls to connect these parameters to subtle features of Quaternary deformation. In the detailed analysis of alluvial terraces, we map each terrace level and sorting them by relative and numerical ages based on previous works (Hedrick et al., 2013; Richard et al., 2019; Rockwell et al. 2022) and we identified seven Quaternary units in the northern sector of La Rinconada. The normalized topographic profiles reveal clear differences between the older levels (Q4- Q7), which are folded and faulted, and younger levels (Q1-Q3), which are predominantly horizontal (Fig.1). The REM provides a good approximation to quantify the differences in elevation between the terraces that we observe in the field. It allows us to perform a statistical analysis of the distribution of heights based on the mapped terraces and shows trends that correspond to the observations. The gradient distribution among these terraces also supports this observation, indicating higher levels of deformation in the older units, likely due to the activity of the La Rinconada fault and other minor structures in its hanging wall. C O N C L U S I O N S The implementation of geometric and topographic methods has allowed us to identify and quantify Quaternary deformation in the La Rinconada area. The use of Relative Elevation Models (REMs) and its derived statistical analysis contributed to a better understanding of the distribution as quantifying the differences in elevation between the terraces that we observe in the field. Also, higher gradients in alluvial terraces may suggest increased deformation because warping or folding. In contrast, terraces that are flat or less deformed tend to have lower gradients. The possibility to plot the topographic profiles contributed to quantify the deformation folds and faults at the submetric level. This detailed morphometric analysis can be used to improve subsurface models. By employing these multiscale approaches, we can gain a deeper understanding of tectonic dynamics and geological development in the area, providing valuable information for future seismic hazard assessments. A C K N O W L E D G E M E N T S This work was supported by project CyT 03-0318 from UNSL and StRATEGy 163-A 2.5 GFZ- CONICET. Le Béon, M., J. Suppe, M. K. Jaiswal, Y.-G. Chen y M. E. Ustaszewski 2014, Deciphering cumulative fault slip vectors from fold scarps: Relationships between long-term and coseismic deformations in central Western Taiwan, J. Geophys. Res. Solid Earth, 119, doi:10.1002/2013JB010794. Mueller, K. y Suppe, J. 1997. Growth of Wheeler Ridge anticline, California: Geomorphic evidence for fault-bend-folding behavior during earthquakes, Journal of Structural Geology, 19, 383-396. Richard, A., Costa, C., Giambiagi, L., Moreno Marcó, C., Ahumada, E.,Vázquez, F. (2019) Neotectónica del extremo austral de la falla La Rinconada, Precordillera Oriental, provincia de San Juan. Revista de la Asociación Geológica Argentina 76 (1): 24-39. Rimando, J., Schoenbohm, L., Costa, C. Owen, L., Cesta, T., Richard, A. y Gardini, C. (2019). Late Quaternary Activity of the La Rinconada Fault Zone, San Juan, Argentina, Tectonics,38. doi: 10.1029/2018TC005321 Rockwell, T., Ragona, D., Meigs, A., Owen, L., Costa, C. y Ahumada, E. 2014. Inferring a thrustrelated earthquake history from secondary faulting: A long rupture record of La Laja Fault, San Juan, Argentina. Bulletin of the Seismological Society of America. 104: 269–284. Rockwell, T.K., Costa, C.H., Meigs, A.J., Ragona, D., Owen, L.A., Murari, M.K., Masana, E., Richard, A.D., 2022. Paleoseismology of the Marquesado-La Rinconada thrust system, Eastern Precordillera of Argentina: Frontiers in Earth. Science 10, 1032357.