The morphology, sediment distribution, and growth pattern of the Amazon cone are similar to those of other deep-sea fans; its sediment, at least during the late Quaternary Period, was deposited in response to glacial-interglacial cycles, and its age of formation is estimated to be middle to late Miocene.
Sedimentation on the Amazon cone, at least during Quaternary time, has been climatically controlled. During high sea-level stands, terrigenous sediment is trapped on the inner continental shelf, and only pelagic sediment is deposited on the cone. During low sea-level stands, the Amazon River discharges terrigenous sediment into the Amazon Submarine Canyon, from where it is easily transported to the cone by gravity-controlled sediment flows. Wisconsin sedimentation rates on the cone were in excess of 30 cm/103 yr.
Average sedimentation rates for the Pleistocene Epoch, based on the extrapolated age (2.2 m.y.) of a prominent acoustic reflector within the cone, range from 50 to 115 cm/103 yr. The Amazon cone began to form about 8 to 15 m.y. B.P. and is thus about one-tenth the age of the Equatorial Atlantic.
- Geological Society of America