The Foundation Chain: Inferring Hotspot-Plate Interaction from a Weak Seamount Trail

The Foundation Chain was first detected using a combination of satellite altimetric and conventional geophysical data (Sandwell 1984, Mammerickx 1992) and described initially as a ∼1350 km long chain of seamounts trending approximately in the direction of the absolute motion of the Pacific Plate (Mammerickx 1992)Fig. 11.1. A significant section of the Foundation Chain lies in a tectonic setting influenced by a change in the direction of sea-floor spreading between 26 and 11 Ma (Herron 1972; Lonsdale 1988; Mayes et al. 1990; Mammerickx 1992). This motion change is reflected in the curvature of the Agassiz Fracture Zone (FZ) and its west-east shift in orientation between the Resolution/Del Cano and Chile FZs Fig. 11.2. A segment of the Nazca plate was transferred to the Pacific Plate during this period of reorganization to form the short-lived Selkirk Microplate Fig. 11.2 (Mammerickx 1992; Tebbens and Cande 1997; Tebbens et al. 1997) via a spreading-ridge propagation event between chron 6C (23.4–24 Ma) and Chron 6(0) (20.2 Ma) (Tebbens and Cande 1997).