Contourites—A Paleovelocity Meter from Geologic Analogues Created from 3D Seismic Data

Abstract

Summary We introduce a method to infer the direction and velocity of paleoocean bottom currents from seismic data using the concept of geologic analogues and integration with modern oceanographic measurements. Colour-processed seismic data provide erosional features at the ocean bottom that can be correlated with oceanographic measurements to validate the modern direction and velocity of the bottom current. We use this calibrated model as the modern analogue to infer paleoocean bottom characteristics of erosional contourite features from subsurface seismic data. We have discarded traditional wavelet-based seismic attributes because of their limited vertical resolution and vertical spatial averaging, which often hides geologic features indicative of paleocurrents. The comparison of a modern analogue from the northern Gulf of Mexico with an ancient analogue from the lower Paleogene of Flemish Pass offshore east Canada shows such level of similarity that we consider the sedimentary processes largely similar, thus enabling us to infer not only the direction of flow but also its velocity. Future analysis will consider contourite depositional features under lower energy conditions and the combination of the depositional and erosional features would help us to better understand the modern day and the ancient formation of contourite depositional systems (CDS). Measurements of paleo-ocean bottom currents impact the understanding of deepwater contourites or reworked turbidites for the reconstruction of the paleoclimate as an input to present day climate change models and for geosciences applied to energy transition (C02 sequestration and hydrocarbon exploration).