Within plate seismicity analysis in the segment between the high Cordillera and the Precordillera of northern Mendoza (Southern Central Andes)

OLIVAR, JULIÁN; NACIF, SILVINA; FENNELL, LUCAS; FOLGUERA, ANDRÉS

Geodesy and Geodynamics

chinese roots global impact

Año: 2018 vol. 9 p. 13 - 24

1674-9847

Crustal seismicity in northwestern Mendoza Province in Argentina, corresponding to the transition zonebetween the ChileanePampean flat subduction zone (26.5e33.5S) and the Southern Central Andesnormal subduction zone to the south, is studied in order to i) identify its relationship with the mappedstructure, ii) determine deformational mechanisms and iii) constrain the geometry of the fold and thrustbelt in the lower crust. Through this, we aim to determine which are the structures that contribute toAndean construction, east of the Frontal Cordillera in Argentina and at the western Principal Cordillera inChile. Data from a temporary local seismic network are reprocessed in order to achieve a precise locationof hypocenters and, whenever possible, to build focal mechanisms. Results are interpreted and comparedwith previous seismic studies and structural models. Analyzed seismicity is grouped around the easternfront of Frontal Cordillera, with hypocenters mainly at depths of 25e40 km. Contrastingly, earthquakes inthe Principal Cordillera to the west are located at the axial Andean sector and Chilean slope, with depthsshallower than 15 km. Obtained focal mechanisms indicate mainly strike-slip displacements, left lateral atFrontal Cordillera and right lateral at Principal Cordillera. Based on these observations, new possiblestructural models are proposed, where seismogenic sources could be either associated with inheritedbasement structures from the CuyaniaeChilenia suture; or correspond to deep-blind thrusts linked with adeeper-than-previously-assumed decollement that could be shared between Frontal Cordillera andwestern Precordillera. This deeper decollement would coincide in turn with the one determined fromreceiver function analysis for the eastern Sierras Pampeanas in previous works, potentially implying acommon decollement all through the fold and thrust belt configuration. Apart from this, a new interpretationof seismogenic structures in Principal Cordillera near the ArgentinaeChile boundary is provided.© 2017 Institute of Seismology, China Earthquake Administration, etc. Production and hosting by ElsevierB.V. on behalf of KeAi Communications Co., Ltd. This is an open access article under the CC BY-NC-NDlicense (http://creativecommons.org/licenses/by-nc-nd/4.0/