Magmatic evolution of a Cordilleran flare-up and its role in the creation of silicic crust

Title of Publication: 
Magmatic evolution of a Cordilleran flare-up and its role in the creation of silicic crust
Ward, Kevin M., Delph, Jonathan R., Zandt, George, Beck, Susan L., and Ducea, Mihai N.
Publication Info: 
Scientific Reports 7, Article number: 9047 (2017) doi:10.1038/s41598-017-09015-5

The role of magmatic processes as a significant mechanism for the generation of voluminous silicic crust and the development of Cordilleran plateaus remains a lingering question in part because of the inherent difficulty in quantifying plutonic volumes. Despite this difficulty, a growing body of independently measured plutonic-to-volcanic ratios suggests the volume of plutonic material in the crust related to Cordilleran magmatic systems is much larger than is previously expected. To better examine the role of crustal magmatic processes and its relationship to erupted material in Cordilleran systems, we present a continuous high-resolution crustal seismic velocity model for an ~800 km section of the active South American Cordillera (Puna Plateau). Although the plutonic-to-volcanic ratios we estimate vary along the length of the Puna Plateau, all ratios are larger than those previously reported (~30:1 compared to 5:1) implying that a significant volume of intermediate to silicic plutonic material is generated in the crust of the central South American Cordillera. Furthermore, as Cordilleran-type margins have been common since the onset of modern plate tectonics, our findings suggest that similar processes may have played a significant role in generating and/or modifying large volumes of continental crust, as observed in the continents today.

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Figure 1. (a) Study area map within the Central Andean Plateau (CAP; <3 km masked) with the Altiplano-Puna Volcanic Complex (APVC) separating the Altiplano basin (northern CAP) and the high-relief Puna Plateau (southern CAP). Blue triangles show Holocene age volcanism of the Central Volcanic Zone (CVZ), gold circles show known ignimbrite eruption calderas, and inverted red triangles show INSAR measured vertical surface deformation centers28. (b) Distribution of Neogene ignimbrite deposits; black lines show the location of transverse lineaments11, 59. (c) Long-wavelength (>50 km) topography. (d) Long-wavelength (>50 km) Bouguer gravity anomalies60. These plots were made using the Generic Mapping Tool61, version 4.5.1 (