MOHOROVICIC DISCONTINUITY DEPTH ANALYSIS BENEATH NORTH PATAGONIAN MASSIF

GÓMEZ DACAL, MARÍA LAURA; CLAUDIA TOCHO; ARAGÓN, EUGENIO

Congreso; IAG Scientific Assembly 2013; 2013

The Mohorovicic discontinuity (Moho) is the surface that limits the Earth?s crust and mantle. It is very important to understand and investigate the dynamic of the Earth?s interior. GOCE gravity satellite has provided a high resolution map of this useful surface, based on the inversion of homogeneous, well-distributed gravimetric data measured by the satellite, which ensures a global coverage. In the present work, a comparison between this map for the North Patagonian massif area and other different results about the depth of the Moho in the zone and a later analysis are made. The North Patagonian Massif is an Argentinean plateau that stands out 500 to 700 m higher in altitude than the surrounding topography. The creation of this plateau was through a sudden uplift without noticeable internal deformation. This quite different mechanical response between the massif and the surrounding areas and a regional negative Bouguer anomaly that could be measured in the area, raise the question about the isostatic compensation state of the massif and motivate us to analyze the crustal thickness in the area to made a contribution to the develop of this unknowns. The comparison is made between the model based in GOCE information that uses gravity information (Barzaghi et al., 2011); and three other models; two of these were created with seismic information (Feng et al., 2006 and Bassin et al., 2000), and the last one with a combination of both gravity and seismic techniques (Tassara y Etchaurren, 2011). The latter was the result of the adaptation to the work area of a three-dimensional density model made with some additional information, mainly seismic, that constrain the surfaces. The work of restriction and adaptation of this model and the later analysis to be then compared, as well as the combination of both seismic models to cover the lack of resolution in some areas, is also presented in the work. According the different models, the crustal thickness of the study zone would be between 36 and 45 Km. and thicker than the surrounding areas. These results talk us about a crust thicker than normal and that could behave as a rigid and independent block. Moreover, it can be observed that there are noticeable differences between gravimetric and seismic models in the North Patagonian Massif area and in its West boundary but almost any difference in the other geographical limits. It is an interesting result and could be related with the isostatic compensation state of the area.