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| Titel |
Rolling in the Deep: Tectonically-triggered sediment and carbon export to the Hadal zone |
| VerfasserIn |
Rui Bao, Michael Strasser, Ann McNichol, Negar Haghipour, Cameron McIntyre, Gerold Wefer  , Timothy Eglinton |
| Konferenz |
EGU General Assembly 2017
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| Medientyp |
Artikel
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| Sprache |
en
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 19 (2017) |
| Datensatznummer |
250140344
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| Publikation (Nr.) |
 EGU/EGU2017-3718.pdf |
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| Zusammenfassung |
| The origin, nature and past variability of sediments accumulating in the abyssal ocean is a
topic that has garnered the attention of many geoscientists. Sediment deposits in deep ocean
trenches, one important type of hadal environment located in tectonically-active regions, hold
great potential for understanding large-scale sediment remobilization and translocation
processes triggered by major earthquakes, and for documenting the past history and
frequency of such events. Establishing the chronostratigraphic framework for hadal zone
sedimentary records constitutes a long-standing issue as they are deposited below the Calcite
Compensation Depth (CCD), resulting in an absence of dateable (i.e. carbonate
biominerals), thereby confounding traditional 14C dating methods. This is one
of the most critical challenges that must be overcome in order to constrain the
provenance and frequency of specific event deposits, and to link them to specific
earthquakes.
In this study, we present results from detailed radiocarbon-based investigation of the
organic matter in a sediment core retrieved from the Japan Trench (> 7.5 km water depth),
proximal to the giant Tohoku-oki earthquake and ensuing tsunami of 2011. Construction
of a high temporal resolution bulk organic carbon (OC) 14C record reveals that
sedimentation in the Japan Trench is interrupted by episodic deposition of sediments
characterized by pre-aged OC. These sedimentary layers coincide with intervals that have
been attributed to past, historically-recorded earthquakes. Moreover, we describe
further 14C measurements on specific thermally-resolved organic matter fractions
from ramped pyrolysis-oxidation of a subset of sediment samples that yield new
chronological constraints in the context of past earthquake history in the Japan
Trench.
Our observations suggest translocation and burial of significant quantities of pre-aged
organic carbon in the hadal environment, shedding new light on the nature and dynamics of
carbon supply to hadal zone, with important implications for the identification of gravity flow
events triggered by non-known tectonic activity in the Japan Trench sediments, and
potentially in other hadal zone sedimentary sequences lying below the CCD where lacking
abundant microfossils for conventional radiocarbon dating and isotope stratigraphy. |
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