Lithospheric 3D gravity modelling using upper-mantle density constraints; towards a charactirization of the crustal configuration in the North Patagonian Massif area, Argentina

GÓMEZ DACAL, MARIA LAURA; TOCHO, CLAUDIA; ARAGÓN, EUGENIO; SIPPEL, JUDITH ; SCHECK-WENDEROTH, MAGDALENA; PONCE, ALEXIS

TECTONOPHYSICS

ELSEVIER SCIENCE BV

Lugar: Amsterdam; Año: 2017 vol. 11

0040-1951

The North Patagonian Massif is an Argentinean plateau that has an average height of 1200 m and standsfrom 500 to 700 m above the neighboring areas. During Paleogene, it suffered a sudden uplift of more than1200 m without noticeable internal deformation; thus, it could be related to isostatic disequilibrium. Toshed light on the geodynamic development of the area it is necessary to characterize the present-day configurationof the crust. In this study, a lithospheric-scale 3D density model was developed by integrating allthe available data of the area with the objective of assessing the depth of the crust?mantle discontinuity(Moho). During the construction of the initial density model, we tested different mantle density scenariosobtained using P- and S-wave velocities from tomographic models, converting them into densities and comparingthe conversions with densities obtained from xenoliths. Below the North Patagonian Massif plateau,we have derived a Moho depth between 40 and 50 km which is from 2 to 7 km deeper than its surroundings.There is an evident correlation between high topography and deep Moho that would indicate isostaticequilibrium at present. The model results provide a new approach to the Moho depth in an area wherethere is no seismic constraining information about this discontinuity. In addition, we found a spatial correlationbetween the variation of the mean crustal density and the location of the Paleozoic terranes that wereproposed to constitute the basement of Argentina.