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This paper presents the gravimetric analysis together with seismic data as an integral application in order to identify the continental-oceanic crust boundary (COB) of the Argentine continental margin from 36 • S to 50 • S in a continuous way. The gravimetric and seismic data are made up of large grids of data obtained from satellite altimetry and marine research. The methodology consists of three distinct methods: (i) the application of enhancement techniques to gravimetric anomalies, (ii) the calculation of crustal thinning from 3-D gravity inversion modelling of the crust-mantle discontinuity and (iii) 2-D gravimetric modelling supported by multichannel reflection and refraction seismic profiles. In the first method, the analytic signal, Theta map, and tilt angle and its horizontal derivative were applied. In the second method, crustal thickness was obtained as the difference in the depths of the crystalline basement and the crust-mantle discontinuity; the latter was obtained via gravimetric inversion. Finally, 2-D modelling was performed from free-air anomalies in two representative sections by considering as restriction surfaces those coming from the interpretation of seismic data. The results of the joint application of enhancement techniques and 2-D and 3-D modelling have enabled continuous interpretation of the COB. In this study, the COB was determined continuously from the integration of 2-D profiles of the enhancement techniques, taking account of crustal thickness and performing 2-D gravimetric modelling. The modelling technique was complemented by regional studies integrated with multichannel seismic reflection and seismic refraction lines, resulting in consistent enhancement techniques.

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This paper analyzes geomagnetic disturbances associated with seismic events in the northern transcurrent margin of the South Sandwich microplate and South American plate, with their epicenter at distances within 350 km from King Edward Point geomagnetic observatory on the archipelago of the Georgias del Sur islands. Geomagnetic field records measured over a one-year period in three observatories of the INTERMAGNET network near the area under study are examined. Anomalous variations in geomagnetic records can be detected within approximately 3 hours before the manifestation of seismic events with a magnitude above 4.4 Mw. Based on the analysis of the differences in horizontal field components among the observatories and the frequency spectrum of the geomagnetic field observations using the wavelet method, oscillations of several nT can be observed before an event, in addition to magnetic peaks with variable amplitude and duration. It is worth noting that, during the period of study, no severe ionospheric effects were recorded as this was a phase of low solar activity (solar cycle 24 minimum). The observation of these potential magnetic precursors suggests that there is a critical preparatory period in a region with geological faults related to the stress generated in the rocks before the built-up energy is released in the hypocenter area, within the lithosphere, which may predict the mechanical motion based on anomalous geomagnetic records.

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