Investigation of the South American continent which is bounded by a passive and an active margin is an important research topic at the GFZ. For the next years a continental-scale seismic profile crossing Argentinia and Chile at a latitude of 40°S (prolonged by marine seismic profiles in the Atlantic and Pacific ocean) was planned in the context of the program 'Geotechnologien' in cooperation with the SFB 267 ('Deformation processes in the Andes'). In December 1998 the BGR recorded a network of combined reflection/refraction lines offshore Argentinia using streamer and OBHs. In order to close the gap between land and marine survey and to test the general propagation of signals for later projects in this area, additional receivers on land have been used recording the airgun signals from the OBH refraction line BGR98-REF1 also onshore. For this, 5 PDAS-100 instruments, each equipped with a MARK L-4C-3D seismometer and a SM-6 geophone string, were deployed at the distances 0 km, -10 km, -38 km, -80 km, -155 km from the coast to the W along 40°S which registered all 2620 airgun sources (175 m spacing) generated at distances between +49 km and +506 km from the coast to the E. First results consist of 5 offset sections showing coherent events up to the maximum offset of 662 km for the geophone strings. Further evaluation in combination with the corresponding offset sections from the 10 OBHs deployed below the airgun line, aimed to obtain a general crustal velocity model reaching from the offshore/onshore transition into the shelf.

Time Frame (experiment)

• December 1998

Principal Investigators

• M. Stiller (GFZ Potsdam))
• A. Schulze (GFZ Potsdam)
• J. Bribach (GFZ Potsdam)
• Ch. Krawczyk (GFZ Potsdam)

Cooperations

• BGR Hannover (contact Dieter Franke)
• Division Exploracion YPF Buenos Aires (contact Pedro Kress)
• Universidad de Buenos Aires (contact Victor A. Ramos)

Methods & Equipment

• Wide-angle reflection/refraction with recording of airgun signals by five 6-channel PDAS instruments

Publications/Results

• Franke, D., Neben, S., Schreckenberger, B., Schulze, A., Stiller, M., Krawczyk, C. M. (2006): Crustal structure across the Colorado Basin, offshore Argentina. - Geophysical Journal International, 165, 3, p. 850-864.
  | GFZpublic | http://doi.org/10.1111/j.1365-246X.2006.02907.x |