Abstract
Transport of continental shelf sediments to the deep ocean can be studied from displaced symbiont-bearing larger benthic foraminifera found in turbidity current deposits. The larger benthic foraminifera habitat depth, physical characteristics and preservation serve as indicators for understanding sediment transport dynamics near the seabed and in the water column. Here, an experiment was designed to explore sediment transport in a closed flume system using simulated high current velocities. Shelf sediments from the Gulf of Eilat/Aqaba, dominated by Amphistegina papillosa and Operculina ammonoides, were subjected to 60 cm s−1 and 80 cm s−1 current velocities while collected in a 10 cm vertical sediment trap. Larger benthic foraminifera abundance, shell physical properties and preservation were analyzed and compared with the original bulk sediments. The experiment results showed that at 80 cm s−1 velocity, larger benthic foraminifera shells of all sizes and preservations are efficiently resuspended and transported in large quantities throughout the water column, as opposed to their transport as bedload by the lower velocity current. Larger benthic foraminifera shape also has a role in the transport distances and accumulation depths. Operculina ammonoides shells were found to be more portable, compared to Amphistegina papillosa, due to their flatter discoid shape. The results suggest that a threshold velocity of ca 80 cm s−1 was needed to generate the thick coarse deposits found in the Gulf of Eilat/Aqaba slope sedimentary record, which were previously suggested to be triggered by large magnitude seismic events. Lower velocities probably winnowed minor amounts of larger benthic foraminifera shells (with little or no coarser sediments) that were deposited as a thin sand layer may point to lower magnitude seismic triggers. In conclusion, larger benthic foraminifera shells are transported and deposited in accordance with their hydrodynamic properties, resulting in assemblage differentiation along the transport pathway. This study shows that the fossil biogenic composition in slope sediments includes valuable information on current velocities, transport dynamics and possible triggers in the geological record.
| Original language | English |
|---|---|
| Pages (from-to) | 1231-1251 |
| Number of pages | 21 |
| Journal | Sedimentology |
| Volume | 69 |
| Issue number | 3 |
| DOIs | |
| State | Published - Apr 2022 |
| Externally published | Yes |
Bibliographical note
Publisher Copyright:© 2021 International Association of Sedimentologists
Funding
This study was supported by the Israeli Ministry of National Infrastructures, Energy and Water Resources (grant No. 210‐17‐035); The Israel Insurance Association (grant No. 100004305); and The Israeli Ministry of Science, Technology and Space (The Eshkol Scholarship Program, No. 3‐9463) sponsoring the full PhD scholarship of Anat Ash‐Mor. Michael Kitin, from the Geological Survey of Israel, Nimer Taha, from the Sedimentological and Environmental Lab at the University of Haifa, Guy Paz from the Israel Oceanographic and Limnological Research, Hadar Elyashiv and Shani Sultan, all are gratefully acknowledged for their technical assistance in this study. Dr. Danna Titelboim is gratefully acknowledged for her assistance with the statistical analysis. Anna Tohar‐Zahav is gratefully acknowledged for the figures graphical and artistic assistance. The crew is sincerely acknowledged for the exploration and extraction of sediments from the Gulf of Eilat/Aqaba for the experiment conducted in this study. The anonymous reviewers are gratefully acknowledged for their constructive comments that helped improve this manuscript. R/V Sam Rothberg This study was supported by the Israeli Ministry of National Infrastructures, Energy and Water Resources (grant No. 210-17-035); The Israel Insurance Association (grant No. 100004305); and The Israeli Ministry of Science, Technology and Space (The Eshkol Scholarship Program, No. 3-9463) sponsoring the full PhD scholarship of Anat Ash-Mor. Michael Kitin, from the Geological Survey of Israel, Nimer Taha, from the Sedimentological and Environmental Lab at the University of Haifa, Guy Paz from the Israel Oceanographic and Limnological Research, Hadar Elyashiv and Shani Sultan, all are gratefully acknowledged for their technical assistance in this study. Dr. Danna Titelboim is gratefully acknowledged for her assistance with the statistical analysis. Anna Tohar-Zahav is gratefully acknowledged for the figures graphical and artistic assistance. The R/V Sam Rothberg crew is sincerely acknowledged for the exploration and extraction of sediments from the Gulf of Eilat/Aqaba for the experiment conducted in this study. The anonymous reviewers are gratefully acknowledged for their constructive comments that helped improve this manuscript.
| Funders | Funder number |
|---|---|
| Gulf of Eilat/Aqaba | |
| Hadar Elyashiv and Shani Sultan | |
| Israel Insurance Association | 100004305 |
| Israel Oceanographic and Limnological Research | |
| Ministry of Science, Technology and Space | 3‐9463 |
| University of Haifa | |
| Ministry of National Infrastructure, Energy and Water Resources | 210‐17‐035 |
| Geological Survey and Mineral Exploration of Iran |
Keywords
- Current velocity
- flume experiment
- sediment transport
- symbiont-bearing larger benthic foraminifera
- taphonomy
- turbidites