Fig. 3: Reconstructions linking the Southern Atlantic-Southwest Indian ridges (SASWIR) subduction-modified mantle anomaly, the Southern Karoo magmatic province, and the mantle structure beneath the South Gondwana margin.
From: Ghost-arc geochemical anomaly at a spreading ridge caused by supersized flat subduction
a Reconstructions of the subduction-influenced Southern Karoo intraplate magmatic province25 at 183 Myr ago showing a close spatial relationship to the SASWIR subduction-modified mantle zone indicated by low-velocity anomalies from the SA2019S S-wave seismic tomography model30. b Mantle structure at 2150 km36 beneath the study area showing the SASWIR subduction-modified mantle zone positioned to the east of the Georgia Islands slab. c High-velocity vote maps confirming the spatial relationship between the Georgia Islands slab and the SASWIR subduction-modified mantle. d Reconstruction considering a whole-mantle slab sinking rate of 1.1 cm/yr37 linking the mantle structure at a depth of 2150 km and a plate kinematic reconstructions at 195 Myr ago32. Trench at 210 Myr ago is also shown in black. This reconstruction shows the SASWIR subduction-modified mantle positioned in front of a landward offset of high-velocity anomalies associated with the presence of the Georgia Island slab38, previously interpreted as the mantle record of the South Gondwana flat slab40,42. e Interpretation of d including late Paleozoic suture zones in Patagonia46,47 that preceded the flat slab. f mid-ocean ridge migration since 120 Myr ago32 over the SASWIR subduction-modified mantle zone. SA South American plate, AF African plate; AP Antarctic Peninsula, SPT South Patagonian terrane, NPMT North Patagonian Massif terrane, SGFS South Gondwana flat slab, and GI Georgia Islands slab.
