TANGO (TransANdean Great Orogeny) is a multi-disciplinary project focused on identifying processes responsible for variations in crustal thickness and uplift along the Andes by exploring the combined roles of the lithosphere, asthenosphere and lower mantle. TANGO is funded by the NSF FRES program.

View N from summit of Cerro Penitentes (4360 m) of the Ca. 12 Ma Santa Maria Conglomerate (SMC; shadowy cliffs in right foreground), which is truncated by the W-dipping Penitentes thrust (left and center middle ground) carrying Jurassic limestone and siliciclastic strata. In the far distance is the south face of Aconcagua (6961 m), and synformal gray and red cliffs to the right (SE) of the mountain are Jurassic strata in thrust contact above light-colored cliffs of the SMC (far right center). Growth structures in the SMC indicate that the Penitentes thrust was active while it was being deposited. (Pete DeCelles)

(A) Topography and major features of the Andes; (B) Map of the depth to Moho interpolated from Tassara and Echaurren (2012) based on a 3D density model of gravity and a large number of seismic studies. Black rectangles represent focus areas of this proposal; 22°S - 24°S: area of thick crust and high shortening; 34°S - 36°S, area of thinner crust and low shortening.

Scientific Questions:

• How did the crust thicken and why is crustal thickening variable along strike?
• Is crustal thickening responsible for surface uplift?
• Are along-strike differences in shortening responsible for differences in orogen width or are such variations a function of differences in erosion, climate, or inherent continental plate structure (top-down control)?
• Alternately, are deeper lithospheric-mantle scale processes operating to control these attributes (bottom-up control)?
• How are mantle-generated stresses transferred into the continental orogenic lithosphere?
• Why was Andean crustal thickening delayed until the Cenozoic, despite a longer history of convergence between the South American and Nazca plates?