According to the proposal by Basile et al. 2020, the Sierra Leone hotspot 201 million years ago was at the centre of the
Central Atlantic Magmatic Province, north of the
Blake Plateau off
North America.[3] The hotspot 180-170 million years ago formed a first oceanic plateau that was subsequently split by the
Mid-Atlantic Ridge around 100 million years ago, forming the
Demerara Plateau and
Guinea Rise. Between 90-70 million years ago the hotspot was under the
African Plate, forming the northern Bathymetrists Seamounts. The Mid-Atlantic Ridge eventually reached the hotspot, resulting 82-55 million years ago in the formation of a second oceanic plateau which was again split by the Mid-Atlantic Ridge to form the
Ceara Rise and
Sierra Leone Rise. Since then, the Sierra Leone hotspot would have been again located on the
African Plate, now generating the southern group of the Bathymetrists Seamounts. 10 million years ago it generated the Knipovich seamount.[4]
The hotspot is currently located about 100 kilometres (62 mi) west of Knipovich seamount;[5] it is presently inactive.[1] According to an alternative proposal by Long et al. 2020, the hotspot would now be centered on 5°17′N25°18′W / 5.28°N 25.3°W / 5.28; -25.3 above a
seismic velocity anomaly in the mantle and in a cluster of seamounts.[6]
Other structures influenced by the hotspot:
Bahamas may be a hotspot track of the Sierra Leone hotspot, which between 170-155 million years ago may have been active on the
North American Plate.[7]
The east-west trending
Bathymetrists Seamounts[5] north of the Sierra Leone Rise.[2] They were capped by
carbonates during the mid-
Eocene.[5] Some of the northern seamounts however produce problems in plate tectonic reconstructions if they are correlated to the Sierra Leone hotspot.[8]