Seismic anisotropy beneath the southern Puna Plateau
Metadata[+] Show full item record
The central Andean plateau is a prime region to study mantle flow above an active plateau margin, where it has been suggested that a link exists between plateau uplift and removal of the lower crust and lithospheric mantle. This study analyzed shear-wave splitting measurements of the southern Puna plateau (25°S to 28°S) caused by anisotropic layers of the mantle in an effort to infer asthenospheric flow patterns. Using 30 teleseismic and 88 local splitting events for vertical constraint, results imply that trench-parallel subslab splitting occurs from retrograde slab motion and shifts to trench-perpendicular as the angle of slab subduction transitions to shallow. The behavior of slab flattening also seems to affect the mantle wedge as splitting above the slab shifts from trench-perpendicular in accordance with absolute plate motion to trench-parallel towards the trench. A toroidal rotation pattern of mantle wedge splitting is also observed around the Cerro Galan ignimbrite region, suggesting a flow obstruction. As a primary source of ignimbrite flare-ups, a delamination event is a likely cause of the detected pattern.