Paleogene buried landscapes and climatic aberrations triggered by mantle plume activity

Abstract

The Icelandic plume, a major mantle upwelling located beneath the North Atlantic Ocean, plays a dominant role in controlling periodic uplift of continental margins and of oceanographic gateways during Cenozoic times. Independent evidence shows that plume activity fluctuates on timescales of ≤1 Myr. Here, we describe and analyze a spectacular sequence of Paleogene buried landscapes imaged on seismic reflection surveys from the continental margin of northwest Europe. These transient landscapes recur on intervals of 2–3 Myrs, coincide with volcanic activity, and exhibit topographic relief of hundreds of meters. They probably represent the surficial expression of thermal fluctuations that spread radially away from the plume conduit. Five landscapes are coeval with global hyperthermal aberrations characterized by negative excursions of δ13C and by positive excursions of Fe intensity, which is a proxy for carbonate dissolution. We propose a causal relationship whereby thermal fluctuations of the mantle plume generate transient uplift and volcanic activity, which act to release significant quantities of greenhouse gases and thus trigger hyperthermal aberrations. A longer period oscillation of δ13C values is superimposed upon these aberrations that is attributable to a combination of silicate weathering and volcanic degassing caused by the interaction of plume activity and plate spreading.