Megaslides in the Foz do Amazonas Basin, Brazilian equatorial margin

Abstract

Recent analysis of multi-channel seismic data provides new evidence that mass-transport deposits have been recurrent elements in the Foz do Amazonas Basin during the Middle-Miocene to Recent. In regions located to the NW and SE of the Amazon Deep-sea Fan, mass movement processes remobilized thick siliciclastic series (up to 1, 000 m) as huge megaslide deposits over areas up to 90, 000 km2. The Pará-Maranhão Megaslide in the SE shows a displaced block (> 104 km2) in association with large mass transport deposits covering an area of more than 105 km2. These deposits are distally bounded by thrust faults, which propagate upwards eventually offsetting the sea floor. In addition, NW of the deep-sea fan, the Amapá Megaslide Complex presents a series of recurrent megaslides in the stratigraphic succession, bounded by listric normal faults and tear zones on the upper slope. Associated remobilized deposits extend from more than 300 km downslope, partially involving the upper channel-levee units of the Amazon Deep-sea Fan. © Springer Science + Business Media B.V. 2010.