10 Sedimentation Rates and Organic Matter
in Various Depositional Environments
10.1 General Aspects
455
10.1.1 Sedimentation and Accumulation Rates
10.1.2 Short- and Long-Term Sedimentation Rates
10.1.3 Potential and Actual Sedimentation Rates
10.2 Sedimentation Rates in Various Depositional
459
Environments
10.2.1 Introduction and Overview
10.2.2 Clastic Sediments
10.2.3 Sedimentation Rates in Carbonate
Depositional Systems
Reefs, Carbonate Platforms, and Shelf
Carbonates
Deep-Water Carbonates
10.2.4 Siliceous Ooze and Radiolarites
10.2.5 Mixed Siliciclastic-Biogenic Sediments
10.2.6 Sedimentation Rates in some Specific
Environments
10.2.7 Sedimentation Rates, Denudation,
Subsidence, and Sea-Level Change
10.2.8 Summary (Sedimentation Rates)
10.3 Production ofOrganic Matter in Various
463
Environments
10.3.1 Introduction
10.3.2 Primary Production (Overview)
10.4 Organic Matter in the Oceans
466
10.4.1 Influx of Terrestrial Organie Matter
10.4.2 Primary Production and Heterotrophie
Organisms
Primary Production
The Food Chain
10.4.3 New Production and Export Production
General Aspects
Adsorbed and Dissolved Organic Matter
Vertical OC Flux through the Water Column
Regional Variation in Export Production
10.5 Organic Matter Preservation in Marine Sediments
10.5.1 General Aspects
469
10.5.2 Organic Carbon Loss on the Sea Floor
Principal Processes
Quantitative Aspects
10.5.3 Inorganic Sediment Accumulation Rates and
OC Burial
Flux Rates and OC Concentrations
Benthic Degradation Loss (Burial Efficiency)
Clastic Dilution
10.5.4 Fluxes and Burial ofOC in Model Basins
10.5.5 Organic Carbon Preservation Factor
10.5.6 Black Shales (Hydrocarbon Source Rocks)
10.5.7 Summary (Production and Preservation of
Organic Matter)
10.1 General Aspects
10.1.1 Sedimentation and Accumulation Rates
It has beeome eommon in the sedimentologiealliterature to distinguish between (linear) sedimentation
rates, SR (sediment thiekness per unit time), and aeeumulation rates, AR (solid sediment mass per unit
area and time). This diserimination is important when
sediments of different porosities are eompared, and it
is indispensable for any kind of sediment budget. In
papers dealing with relatively young sediments of
high porosity, for example sediment eores reeovered
by seientifie oeean drilling, mostly aeeumulation
rates are used (e.g., Van Andel 1983; Ehrrnann and
Thiede 1985).
Both sedimentation and aeeumulation rates are
determined for vertieal seetions of the thiekness, z,
taken between dated lower and upper boundaries
spanning the time interval, t. The sedimentation rate,
SR, represents an average value for the seetion eonsidered. It is based on the ineorreet assumption that
sediment deposition during t oeeurred eontinuously
at a eonstant rate.
SR = z/t
(10.1 )
SR is ealculated ip mmla (a = year), mmlka (1 ka =
1000 years), emlka, or mlMa (1 Ma = 10 6 years;
1 cm/ka = 10 mlMa). In the following text, the latter
two notations are mainly used.
It is obvious that SR is not an accurate scale to describe the
deposition of solid partic1es quantitatively. The high
porosites of fresh sediments are later reduced by compaction under the load of younger sediments (Sect. 13.2).
Thus, linear sedimentation rates calculated without taking
porosity into account become lower with decreasing porosity. However, if sediments have undergone deep burial and
lithification, their differences in porosities become less
pronounced. The errors associated with dating of seetion
boundaries andlor the assumption of steady state deposition
in Various Depositional Environments
10.1 General Aspects
455
10.1.1 Sedimentation and Accumulation Rates
10.1.2 Short- and Long-Term Sedimentation Rates
10.1.3 Potential and Actual Sedimentation Rates
10.2 Sedimentation Rates in Various Depositional
459
Environments
10.2.1 Introduction and Overview
10.2.2 Clastic Sediments
10.2.3 Sedimentation Rates in Carbonate
Depositional Systems
Reefs, Carbonate Platforms, and Shelf
Carbonates
Deep-Water Carbonates
10.2.4 Siliceous Ooze and Radiolarites
10.2.5 Mixed Siliciclastic-Biogenic Sediments
10.2.6 Sedimentation Rates in some Specific
Environments
10.2.7 Sedimentation Rates, Denudation,
Subsidence, and Sea-Level Change
10.2.8 Summary (Sedimentation Rates)
10.3 Production ofOrganic Matter in Various
463
Environments
10.3.1 Introduction
10.3.2 Primary Production (Overview)
10.4 Organic Matter in the Oceans
466
10.4.1 Influx of Terrestrial Organie Matter
10.4.2 Primary Production and Heterotrophie
Organisms
Primary Production
The Food Chain
10.4.3 New Production and Export Production
General Aspects
Adsorbed and Dissolved Organic Matter
Vertical OC Flux through the Water Column
Regional Variation in Export Production
10.5 Organic Matter Preservation in Marine Sediments
10.5.1 General Aspects
469
10.5.2 Organic Carbon Loss on the Sea Floor
Principal Processes
Quantitative Aspects
10.5.3 Inorganic Sediment Accumulation Rates and
OC Burial
Flux Rates and OC Concentrations
Benthic Degradation Loss (Burial Efficiency)
Clastic Dilution
10.5.4 Fluxes and Burial ofOC in Model Basins
10.5.5 Organic Carbon Preservation Factor
10.5.6 Black Shales (Hydrocarbon Source Rocks)
10.5.7 Summary (Production and Preservation of
Organic Matter)
10.1 General Aspects
10.1.1 Sedimentation and Accumulation Rates
It has beeome eommon in the sedimentologiealliterature to distinguish between (linear) sedimentation
rates, SR (sediment thiekness per unit time), and aeeumulation rates, AR (solid sediment mass per unit
area and time). This diserimination is important when
sediments of different porosities are eompared, and it
is indispensable for any kind of sediment budget. In
papers dealing with relatively young sediments of
high porosity, for example sediment eores reeovered
by seientifie oeean drilling, mostly aeeumulation
rates are used (e.g., Van Andel 1983; Ehrrnann and
Thiede 1985).
Both sedimentation and aeeumulation rates are
determined for vertieal seetions of the thiekness, z,
taken between dated lower and upper boundaries
spanning the time interval, t. The sedimentation rate,
SR, represents an average value for the seetion eonsidered. It is based on the ineorreet assumption that
sediment deposition during t oeeurred eontinuously
at a eonstant rate.
SR = z/t
(10.1 )
SR is ealculated ip mmla (a = year), mmlka (1 ka =
1000 years), emlka, or mlMa (1 Ma = 10 6 years;
1 cm/ka = 10 mlMa). In the following text, the latter
two notations are mainly used.
It is obvious that SR is not an accurate scale to describe the
deposition of solid partic1es quantitatively. The high
porosites of fresh sediments are later reduced by compaction under the load of younger sediments (Sect. 13.2).
Thus, linear sedimentation rates calculated without taking
porosity into account become lower with decreasing porosity. However, if sediments have undergone deep burial and
lithification, their differences in porosities become less
pronounced. The errors associated with dating of seetion
boundaries andlor the assumption of steady state deposition