248
sampling resolution as over sampling (i.e., more than just the depositional unit) will
lead to dilution of event sedimentation with non-event sedimentation. Dilution of
the sedimentary signature of an event can lead to changing interpretations of impact
and/or making it more difficult to detect in the sedimentary record. This is particularly important for more subtle indicators of a sedimentation event, and increased
sampling resolution would increase the potential for detection as well as the number
of analyses performed providing a more robust record. Also, of consideration is the
required sampling resolution to obtain comparable baseline sedimentological data
on similar time scales (months/years) for direct comparison to determine deviations,
from baseline, of sedimentation events. Often, baseline sedimentation is at lower
rates as compared to events.
14.7.4 MultiDisciplinary Approach
The simultaneous collection of up to eight cores allowed for a multidisciplinary
approach for investigating DWH blowout impacts in the sedimentary record. This
provided a more robust definition of the sedimentary signature and detection of the
event. As most diagnostic indicators were subtle, the combination of multiple lines
of evidence for the presence of oil-contaminated sediments was extremely valuable
for defining the impacts of spatial deposition. It also assisted in determining the
sediment sources (i.e., surface waters, etc.), depositional mechanisms, and biological/ecological impacts.
14.8 Conclusions
The DWH blowout event led to the formation of MOSSFA and a depositional pulse
to the deep-sea benthos in the NEGoM in the Fall of 2010. A time series of sediment
cores from four sites collected annually between 2010 and 2016 characterizes the
event, post-event response, and stabilization of the sedimentary system with respect
to sedimentation rates, sedimentology, and preservation potential. All sites collected
in 2010 and early 2011 had large excursions in % silt and high
234
Th xs Inventories
and MAR indicating a depositional pulse with high sedimentation rates associated
with the observed MOSSFA event. There were no distinctive changes in sediment
composition associated with the depositional pulse, as the MOSSFA event stripped
existing particles from the water column and did not significantly change the
source(s) of sediment in either the siliciclastic or carbonated dominated regions. In
the following years, 2011–2012,
234
Th xs Inventories and MAR were lower (at all
sites) indicating lower sedimentation rates and a lack of bioturbation following the
event. Over this period the initial deviations in % silt began to become undetectable
in the sedimentary record. Beginning in 2013 and continuing through 2016, there
was a site-specific return of bioturbation and stabilization of the sedimentary
R. A. Larson et al.
sampling resolution as over sampling (i.e., more than just the depositional unit) will
lead to dilution of event sedimentation with non-event sedimentation. Dilution of
the sedimentary signature of an event can lead to changing interpretations of impact
and/or making it more difficult to detect in the sedimentary record. This is particularly important for more subtle indicators of a sedimentation event, and increased
sampling resolution would increase the potential for detection as well as the number
of analyses performed providing a more robust record. Also, of consideration is the
required sampling resolution to obtain comparable baseline sedimentological data
on similar time scales (months/years) for direct comparison to determine deviations,
from baseline, of sedimentation events. Often, baseline sedimentation is at lower
rates as compared to events.
14.7.4 MultiDisciplinary Approach
The simultaneous collection of up to eight cores allowed for a multidisciplinary
approach for investigating DWH blowout impacts in the sedimentary record. This
provided a more robust definition of the sedimentary signature and detection of the
event. As most diagnostic indicators were subtle, the combination of multiple lines
of evidence for the presence of oil-contaminated sediments was extremely valuable
for defining the impacts of spatial deposition. It also assisted in determining the
sediment sources (i.e., surface waters, etc.), depositional mechanisms, and biological/ecological impacts.
14.8 Conclusions
The DWH blowout event led to the formation of MOSSFA and a depositional pulse
to the deep-sea benthos in the NEGoM in the Fall of 2010. A time series of sediment
cores from four sites collected annually between 2010 and 2016 characterizes the
event, post-event response, and stabilization of the sedimentary system with respect
to sedimentation rates, sedimentology, and preservation potential. All sites collected
in 2010 and early 2011 had large excursions in % silt and high
234
Th xs Inventories
and MAR indicating a depositional pulse with high sedimentation rates associated
with the observed MOSSFA event. There were no distinctive changes in sediment
composition associated with the depositional pulse, as the MOSSFA event stripped
existing particles from the water column and did not significantly change the
source(s) of sediment in either the siliciclastic or carbonated dominated regions. In
the following years, 2011–2012,
234
Th xs Inventories and MAR were lower (at all
sites) indicating lower sedimentation rates and a lack of bioturbation following the
event. Over this period the initial deviations in % silt began to become undetectable
in the sedimentary record. Beginning in 2013 and continuing through 2016, there
was a site-specific return of bioturbation and stabilization of the sedimentary
R. A. Larson et al.