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Diatom ooze: Crucial for the generation of submarine mega-slides?.
Urlaub, Morelia , Geersen, Jacob , Krastel, Sebastian and Schwenk, Tilmann (2018) Diatom ooze: Crucial for the generation of submarine mega-slides?. Geology, 46 (4). pp. 331-334. DOI 10.1130/G39892.1.
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Abstract
Numerous studies invoke weak layers to explain the occurrence of submarine mega-slides (>100 km3), in particular those on very gentle slopes (<3°). Failure conditions are thought to be met only within this layer, which is embedded between stable sediments. Although key to understanding failure mechanisms, little is known about the nature and composition of such weak layers, mainly because they are destroyed with the landslides. This study is the first to place detailed constraints on the weak layer for one of the submarine mega-slides that occurred on the nearly flat, subtropical, northwest African continental slopes. Integrating results from the Ocean Drilling Program with high-resolution seismic reflection data, we show that the failure surfaces traced into the undisturbed sedimentary sequence coincide with thin (<10 m) diatom ooze layers capped by clay. As diatom oozes are common on many continental margins, we suggest a new margin-independent failure mechanism to explain submarine mega-slides at low-gradient continental slopes globally. Diatom oozes are susceptible to building up excess pore fluid during burial due to their high compressibility and water content. If a low-permeable clay cap prevents upward drainage, excess pore pressures accumulate at the ooze-clay interface, causing the shearing resistance to increase at a lower rate than the shear stress until failure can occur. Changes in global climate affect the abundance of diatoms and thus formation of diatom oozes, thereby preconditioning the sediments for failure. However, the actual timing of failure is independent of environmental changes.
Document Type: | Article |
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Keywords: | Diatom ooze, submarine mega-slides |
Research affiliation: | MARUM Kiel University > Kiel Marine Science OceanRep > The Future Ocean - Cluster of Excellence OceanRep > GEOMAR > FB4 Dynamics of the Ocean Floor > FB4-GDY Marine Geodynamics Kiel University |
Refereed: | Yes |
Open Access Journal?: | No |
Publisher: | GSA, Geological Society of America |
Related URLs: | |
Expeditions/Models/Experiments: | |
Date Deposited: | 12 Feb 2018 11:43 |
Last Modified: | 08 Feb 2021 07:43 |
URI: | https://oceanrep.geomar.de/id/eprint/41894 |
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