Amazon Basin (sedimentary basin)

The Amazon Basin is a major sedimentary basin located roughly at the middle and lower course of the Amazon River, south the Guiana Shield and north of the Central Brazilian Shield. The basin develops on a rift that originated possibly about 550 million years ago during the Cambrian. Parts of the rift were reactivated during the opening of the South Atlantic.

The basin has an elongate shape with a SWW-NEE orientation. It long axis runs from the vicinity of Manaus to the area near the confluence of Xingu River with the Amazon River.

...
Wikipedia