The Ioffe Drift

The Discovery of the calcareous Ioffe Drift in the SW Atlantic in 2010 opens new perspectives in the contourite theory. Although demonstrating similar behavior relative to bottom water dynamics, rather rare and poorly studied calcareous contourites differ from their terrigenous analogs in origin, grain-size distribution, chemical and mineral composition of sedimentary particles. The detailed multidisciplinary study of the Ioffe Drift produces new knowledge on biogenic contourites deposited in pelagic realm, in conditions of low biological productivity and terrigenous material supply, under the influence of the Antarctic Bottom Water flow from the Vema Channel. The major intervals of prevailing erosion are inferred on the drift from 2.51/2.59 to 1.9 Ma and from 1.6 to 0.81 Ma thus indicating strong paleoceanographic changes most likely associated with the reorganization of deep-sea circulation and increased bottom water production in the Southern Ocean during the Early Pleistocene and,in particular, around the Mid-Pleistocene Transition.

Auteur

Prof. Ivar Murdmaa, habilitated DSci on geology and mineralogy, Senior Researcher at Shirshov Institute of Oceanology RAS, participant of 37 marine expeditions including 4 deep sea drilling legs. His major scientific interests include lithology, sedimentology, facies and formations of oceanic sediments, ferromanganese nodules. During the last decade, he studied the lithology and formation of contourites from the Southern and Central Atlantic. Prof. Elena Ivanova, habilitated DSci on oceanology and marine geology, Head of the Laboratory of Paleoceanology at Shirshov Institute of Oceanology RAS, participant of 22 marine expeditions and Chief scientist in 6 of them, guest scientist at several research institutes in France, UK, Germany, USA. Her major scientific interests include mechanisms on global teleconnections based on the study of high-resolution paleodata timeseries, contourite stratigraphy and bottom-water circulation in the Southern and Central Atlantic.

Contenu

Preface

1. Introduction

2. Regional setting

2.1 Physiography

2.2 Oceanography

2.3 Geology 2.4 Sedimentology

4. Regional stratigraphic frames based on calcareous microfossils

5. Materials

6. The Ioffe Drift geomorphology and seismic stratigraphy

6.1 Bathymetry

6.2 Acoustic structure of the drift

6.3 Seismic facies as evidence for the contourite origin of the drift

7. Lithology and sedimentology 7.1. Lithostratigraphy of core sections

7.2 Grain size distribution

7.3 Geochemistry (CaCO3, TOC, XRF)

7.4 Magnetic susceptibility and color reflectance

7.5 Mineralogy 7.7 Sedimentation processes

8. Micropaleontology and stratigraphy

9.1 Planktic foraminiferal assemblages and biostratigraphic zones

9.2 Nannofossil assemblages and biostratigraphic zones 9.3 Correlation of foraminiferal and nannofossil zones in the Ioffe Drift

9.4 Correlation of foram and nannofossil zones in the Ioffe Drift and Rio Grande Rise

9. Ferromanganese nodules

10. Hiatuses and core correlations

11. The Ioffe Drift history and mechanisms of sedimentation

12. Conclusions and Perspectives

References

Attachment (SCAN Images)

Index