W. U. Ehrmann; J. Thiede:

History of mesozoic and cenozoic sediment fluxes to the North Atlantic Ocean

1985. IV, 109 pages, 26 figures, 5 tables, 16x24cm, 290 g
Language: English

(Contributions to Sedimentary Geology, Volume 15)

ISBN 978-3-510-57015-7, paperback, price: 34.00 €

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Content Description top ↑

This history of the Mesozoic and Cenozoic depositional paleoenvironments of the North Atlantic Ocean has been written based on a detailed analysis of all accessible deep-sea drill sites, of temporal and spatial distributions of major pelagic sediment facies, of hiatuses, of bulk sediment accumulation rates, and of concentrations and fluxes of the most important deep-sea sediment components. Spatial patterns of theses variables have been evaluated based on data plotted into palinspastic maps, which are tracing stepwise for 30 time slices the paleophysiographic evolution of the zonal North Atlantic and its epicontinental seas.

The depositional history of the North Atlantic can be subdivided into three major phases when processes controlling sediment input and sediment distribution in this ocean basin differed:
a) A Late Jurassic and Early Cretaceous phase: Clastic terrigenous sediment components as well as biogenic pelagic ones accumulated rapidly under highly productive surface water masses over the entire ocean basin.
b) A mid- to Late Cretaceous to Early Miocene phase: Generally relatively little terrigenous and pelagic biogenic sediment reached the North Atlantic ocean floor.
c) A Middle Miocene to Recent phase: Accumulation rates of biogenic and terrigenous deep-sea sediment components increased dramatically up to Quaternary times, rates of hiatus formation and henceforth the intensity of deep-water circulation seemed to have decreased.

Reconstructions of the paleodepth distributions of hiatuses have revealed maxima of hiatus occurrence in the western main North Atlantic basin in two depth levels, namely close to 5 km and 2,2-4 km paleodepth, but in the eastern basin only in one level at 1,2-1,8 km paleodepth. Continued sea floor spreading had an important impact on the depositional environment in this ocean.

Contents top ↑

1. Introduction 3
Purpose and approach of this study — Paleophysiography of the
North Atlantic Ocean
2. Methods 14
3. Distribution of major sediment facies 22
4. Concentrations of major sediment components 31
Concentrations of terrigenous material — Concentrations of biogenic
sediment components
5. Fluxes of major sediment components: Temporal and spatial patterns 36
Fluxes of bulk sediment and terrigenous sediments (Regional
patterns, Temporal and paleobathymetric patterns) — Fluxes of
biogenic components (Fluxes of calcareous sediment components,
Fluxes of opaline sediment components)
6. Interruptions of sediment flux of the sea floor: Hiatuses 80
Hiatus distribution in the North Atlantic Ocean: Temporal patterns
(The entire North Atlantic, Regional distribution) — Paleobathymetry
of hiatus distributions in the Mesozoic and Cenozoic North
Atlantic Ocean — Discussion
7. History of North Atlantic sedimentation 91
Conclusions/Acknowledgements/References cited 101-105