Terrestrial Organic Matter in Marine Sediments
557
comprise an extremely low volume-% of the bulk
sediment. For example, ifPOM of a deep-sea ooze
containing 1% TOC is analyzed for its volume-%,
only 20 counts are expected on organic particles,
if 1000 counts are considered. However, since a
reliable estimation of the composition of OM requires at least 300-500 counts on organic particles
(Traverse 1988), a total of 15,000-25,000 counts
would be necessary for the determination of
volume-%. In contrast, if POM is determined as
grain-%, the volume will not be considered but the
relative maceral composition is more reliable. Organic petrologic studies performed on fossil and
recent deep-sea sediments revealed that a high
detrital character of the macerals is typical
(Combaz et al. 1974; Lallier-Verges et al. 1990;
Wiesner et al. 1990; Littke 1993; Wagner 1998,
1999). Hence, the aspect of volume presumably is
of minor relevance when relative proportions of
• glacial sediments
o interglacial sediments
30
40
grain percentages of marine macerals
Fig. 4. Comparison of quantitative marine OM estimates
based on grain percentage and volume percentage
counting obtained from late Quatemary glacial and interglacial Norwegian-Greenland Sea deposits (modified
after Wagner 1993). Correlation of results from different
counting methods reveal average deviations around
20%, suggesting that interpretation of grain percentage
records of particulate OM leads to similar results as
volume percentage data.
marine vs. terrigenous OM are estimated on the
basis of grain-%. Comparison of volume-% and
grain-% determined on a set of deep-sea samples
reveal a fairly good correlation between both types
of counting (Fig. 4). It is therefore suggested that
grain-% data can be taken similar as volume-%
data, providing an alternative proxy for the assessment of marine vs. terrigenous OM.
Bion1arkerApproaches
Characterization of individual organic components
covers the broad field of biomarker analysis. With
regard to the enormouS diversity of the presently
known biomarkers and the rapid analytical
progress, this study does not attempt to give a balanced overview ofthe present stage of knowledge
but rather focuses on a very small number of
well established markers for the identification of
terrigenous OM in marine sediments (for further
information especially on diagenetic effects on
biomarker records see Engel and Macko 1993).
Terrestrial biomarkers used in most
recent paleoceanographic studies are n-alkanes, nalkohols, and fatty acids (e.g Prahl and MUhlhausen
1989; Westerhausen et al. 1993; Fahl and Stein
1997) and lignin oxidation products (Hedges and
Mann 1979; GotH et al. 1997). Chemical components of surface waxes of vascular plants reveal
source specific features with regard to their typical chain length and carbon number preference.
The basic work for a quantitative interpretation of
terrestrial biomarkers in marine sediments was introduced by Prahl and Carpenter (1984) who examined the spatial distribution of n-alkanes in continental shelf and slope deposits off the southern
coast of Washington. This concept was developed
by Prahl and MUhlhausen (1989) and Prahl et al.
(1989) who applied a simple binary mixing model
using fatty acids to assess terrigenous organic carbon in marine sediments. Application of this approach to late Quaternary sediments of the eastern Pacific Ocean led to the conclusion that on
average more than 20% ofthe TOC is ofterrestrial origin, being introduced by long-range eolian
transport. The terrestrial endmember value used in
this approach, however, is problematic to evaluate
since a number of fundamental assumptions
557
comprise an extremely low volume-% of the bulk
sediment. For example, ifPOM of a deep-sea ooze
containing 1% TOC is analyzed for its volume-%,
only 20 counts are expected on organic particles,
if 1000 counts are considered. However, since a
reliable estimation of the composition of OM requires at least 300-500 counts on organic particles
(Traverse 1988), a total of 15,000-25,000 counts
would be necessary for the determination of
volume-%. In contrast, if POM is determined as
grain-%, the volume will not be considered but the
relative maceral composition is more reliable. Organic petrologic studies performed on fossil and
recent deep-sea sediments revealed that a high
detrital character of the macerals is typical
(Combaz et al. 1974; Lallier-Verges et al. 1990;
Wiesner et al. 1990; Littke 1993; Wagner 1998,
1999). Hence, the aspect of volume presumably is
of minor relevance when relative proportions of
• glacial sediments
o interglacial sediments
30
40
grain percentages of marine macerals
Fig. 4. Comparison of quantitative marine OM estimates
based on grain percentage and volume percentage
counting obtained from late Quatemary glacial and interglacial Norwegian-Greenland Sea deposits (modified
after Wagner 1993). Correlation of results from different
counting methods reveal average deviations around
20%, suggesting that interpretation of grain percentage
records of particulate OM leads to similar results as
volume percentage data.
marine vs. terrigenous OM are estimated on the
basis of grain-%. Comparison of volume-% and
grain-% determined on a set of deep-sea samples
reveal a fairly good correlation between both types
of counting (Fig. 4). It is therefore suggested that
grain-% data can be taken similar as volume-%
data, providing an alternative proxy for the assessment of marine vs. terrigenous OM.
Bion1arkerApproaches
Characterization of individual organic components
covers the broad field of biomarker analysis. With
regard to the enormouS diversity of the presently
known biomarkers and the rapid analytical
progress, this study does not attempt to give a balanced overview ofthe present stage of knowledge
but rather focuses on a very small number of
well established markers for the identification of
terrigenous OM in marine sediments (for further
information especially on diagenetic effects on
biomarker records see Engel and Macko 1993).
Terrestrial biomarkers used in most
recent paleoceanographic studies are n-alkanes, nalkohols, and fatty acids (e.g Prahl and MUhlhausen
1989; Westerhausen et al. 1993; Fahl and Stein
1997) and lignin oxidation products (Hedges and
Mann 1979; GotH et al. 1997). Chemical components of surface waxes of vascular plants reveal
source specific features with regard to their typical chain length and carbon number preference.
The basic work for a quantitative interpretation of
terrestrial biomarkers in marine sediments was introduced by Prahl and Carpenter (1984) who examined the spatial distribution of n-alkanes in continental shelf and slope deposits off the southern
coast of Washington. This concept was developed
by Prahl and MUhlhausen (1989) and Prahl et al.
(1989) who applied a simple binary mixing model
using fatty acids to assess terrigenous organic carbon in marine sediments. Application of this approach to late Quaternary sediments of the eastern Pacific Ocean led to the conclusion that on
average more than 20% ofthe TOC is ofterrestrial origin, being introduced by long-range eolian
transport. The terrestrial endmember value used in
this approach, however, is problematic to evaluate
since a number of fundamental assumptions