Lithospheric Dynamics in the Southernmost Andean Plateau (PUDEL)

Time frame: 2009 - 2011

Summary
We propose to address fundamental questions on the processes that form, modify and destroy continental lithosphere and control lithospheric dynamics along Andean-type continental margins through a collaborative international passive-source seismic experiment in the southern Puna of the Central Andean plateau (25°S to 28°S). Seismic studies in this geophysically little studied region are particularly pertinent as the southern Puna is anomalous with respect to the rest of the Andean plateau in having a distinct magmatic and structural history, a large deficit in crustal shortening compared to its elevation, an underlying slab with a transitional dip between a steeper segment to the north and the Chilean flat-slab to the south, and preliminary Sn attenuation evidence for a thinner continental lithosphere. Within this framework, the experiment is designed to use receiver functions and tomography along with other seismic tools to constrain: 1) the seismic structure and thickness of the continental lithospheric mantle, 2) the thickness, bulk composition, and seismic structure of the crust, 3) the geometry and rheology of the subducting slab over a prominent gap in intermediate depth seismicity, 4) the nature of mantle deformation in a transition from steep to flat subduction and 5) to test the hypothesis of lithospheric delamination in this region.
A total number of 73 seismographs has been deployed for about two years (2007-2009). 30 stations come from Germany, 43 stations from US . Surface wave tomography, ambient noise analysisi, shear wave splitting and local seismicity will be mainly done by the US partners, while analysis of teleseismic receiver functions and teleseismic tomography will be mainly fulfilled at the FU Berlin and GFZ Potsdam. These results will be combined with existing and ongoing geologic and geochemical studies, conducted in Cornell, to develop a robust geodynamic model for the evolution of the southern Puna for the last ~8 Ma. The South American partners will participate in all research fields.

Priciple Invesgators
Dr. Benjamin Heit (GFZ Potsdam)
Dr. Xiaohui Yuan (GFZ Potsdam)
Prof. Dr. Rainer Kind (FU Berlin and GFZ Potsdam)
PD Günter Asch (GFZ Potsdam)

Colaborations
Dr. Eric Sandvol, University of Missouri-Columbia
Prof. Suzanne Kay, Cornell University
Prof. Larry Brown, Cornell University
Prof. Ricardo Alonso, University of Salta
Prof. Beatriz Coira, University of Jujuy
Dr. Patricia Alvarado. INPRES Earthquake Center of and University of San Juan
Dr. Diana Comte, University of Santiago de Chile