5 Oceanic Sediments
5.1
5.2
5.3
Introduction
Water Circulation in the Oceans
5.2.1 Salinity and Density ofOcean Water
5.2.2 Density Stratification and the Pycnocline
5.2.3 Oceanic Water Circulation
Thermohaline circulation
Wind-Driven Circulation
Combined Effects of Thermohaline and
Wind-Driven Circulation
5.2.4 Current Speeds, Transport ofWater Masses,
Heat, and Nutrients
5.2.5 Summary (Ocean Water Circulation)
Hemipelagic and Pelagic Deep-Sea Sediments
5.3.1 Sources, Transport, and Classification of
Deep-Sea Sediments
Sediment Sources
Classification ofDeep-Sea Sediments
Transport Mechanisms and Deposition
5.3.2 Deep-Sea Carbonates and Carbonate
Dissolution
Biogenic Carbonate Production
The Chalk Problem
Carbonate Dissolution
Production and Dissolution ofCarbonate:
a Dynamic Equilibrium
5.3.3 Red Clay and Manganese Nodules
5.3.4 Sediments in Zones ofUpwelling
General Aspects
Coastal Upwelling and Its Sediments
5.3.5 Siliceous Sediments
Biogenic Production of Opaline Silica
Preservation ofOpaline Silica
183
183
188
Areal Distribution ofBiosiIiceous Sediments
Silica Diagenesis and Bedded Cherts
5.3.6 Summary (Hemipelagic and Pelagic Sediments)
5.3.7 Marine Phosphorites
Sources of phosphorus and phosphate
precipitation
Secondary Enrichment ofPhosphorite
Summary (Phosphorites)
5.3.8 Sediments on Marginal and Oceanic Plateaus,
Ridges and Seamounts
Deep Plateaus and Seamounts
Siopes and Basins Close to Submarine Plateaus
Submarine Ridge and Basin Topography
Summary (Plateaus, Ridges, and Associated
Basins)
5.4 Gravity Mass Flow Deposits and Turbidites.
210
5.4.1 Introduction
5.4.2 Gravity Mass Movements and Mass Flows
in the Ocean
Types of Gravity Mass Transport
Preferential Sites ofMass Movements
Deposits ofDebris Flows and Mud Flows
5.4.3 Turbidity Currents and Turbidites
Suspension (Turbidity) Currents
Types of Turbidites and Their Characteristics
Other Characteristics ofTurbidites
Bed Sets and Proximal-Distal Trends
of Turbidite Sequences
5.4.4 Volumes, Travel Distances and Frequency
ofMass Flow Deposits
5.4.5 Deep-Sea Fan Associations
Types ofDeep-Sea Fans
The Sediment Distribution System of
Deep-Sea Fans
Paleo-Current Directions in Deep-Sea Fans
Active and Inactive Phases ofFan Deposition
Sedimentation Rates ofDeep-Sea Fans
5.4.6 Deep-Sea Channels
5.4.7 Summary (Gravity Mass Flows, Turbidites,
Deep-Sea Fans)
5.5 Erosion and Redeposition ofDeep-Sea Sediments 235
5.5.1 Deep Bottom-Current Erosion
5.5.2 Contourites and Sediment Drifts
5.5.3 Stratigraphic Gaps in the Deep-Sea Record
5.5.4 Summary (Deep-Marine Erosion and
Redeposition)
5.6 Paleoceanogrgphy
238
5.6.1 Introduction
5.6.2 Processes Influencing Climate, Ocean
Circulation, and Marine Sediments
Solar Radiation and Feedback Systems
Greenhouse Gases
Air-Sea CO2 Exchange: the Solution Pump and
the Biological Pump
Further Air-Sea-Land Interactions
5.6.3 The Conveyer Belt in the Modem Oceans
5.6.4 Effects ofLow Sea Level
5.6.5 Oceanic Gateways and Paleo-Ocean Circulation
5.6.6 The Cretaceous Ocean
5.6.7 The post-Cretaceous Cooling
5.6.8 Surnrnary (Paleoceanography)
5.1
5.2
5.3
Introduction
Water Circulation in the Oceans
5.2.1 Salinity and Density ofOcean Water
5.2.2 Density Stratification and the Pycnocline
5.2.3 Oceanic Water Circulation
Thermohaline circulation
Wind-Driven Circulation
Combined Effects of Thermohaline and
Wind-Driven Circulation
5.2.4 Current Speeds, Transport ofWater Masses,
Heat, and Nutrients
5.2.5 Summary (Ocean Water Circulation)
Hemipelagic and Pelagic Deep-Sea Sediments
5.3.1 Sources, Transport, and Classification of
Deep-Sea Sediments
Sediment Sources
Classification ofDeep-Sea Sediments
Transport Mechanisms and Deposition
5.3.2 Deep-Sea Carbonates and Carbonate
Dissolution
Biogenic Carbonate Production
The Chalk Problem
Carbonate Dissolution
Production and Dissolution ofCarbonate:
a Dynamic Equilibrium
5.3.3 Red Clay and Manganese Nodules
5.3.4 Sediments in Zones ofUpwelling
General Aspects
Coastal Upwelling and Its Sediments
5.3.5 Siliceous Sediments
Biogenic Production of Opaline Silica
Preservation ofOpaline Silica
183
183
188
Areal Distribution ofBiosiIiceous Sediments
Silica Diagenesis and Bedded Cherts
5.3.6 Summary (Hemipelagic and Pelagic Sediments)
5.3.7 Marine Phosphorites
Sources of phosphorus and phosphate
precipitation
Secondary Enrichment ofPhosphorite
Summary (Phosphorites)
5.3.8 Sediments on Marginal and Oceanic Plateaus,
Ridges and Seamounts
Deep Plateaus and Seamounts
Siopes and Basins Close to Submarine Plateaus
Submarine Ridge and Basin Topography
Summary (Plateaus, Ridges, and Associated
Basins)
5.4 Gravity Mass Flow Deposits and Turbidites.
210
5.4.1 Introduction
5.4.2 Gravity Mass Movements and Mass Flows
in the Ocean
Types of Gravity Mass Transport
Preferential Sites ofMass Movements
Deposits ofDebris Flows and Mud Flows
5.4.3 Turbidity Currents and Turbidites
Suspension (Turbidity) Currents
Types of Turbidites and Their Characteristics
Other Characteristics ofTurbidites
Bed Sets and Proximal-Distal Trends
of Turbidite Sequences
5.4.4 Volumes, Travel Distances and Frequency
ofMass Flow Deposits
5.4.5 Deep-Sea Fan Associations
Types ofDeep-Sea Fans
The Sediment Distribution System of
Deep-Sea Fans
Paleo-Current Directions in Deep-Sea Fans
Active and Inactive Phases ofFan Deposition
Sedimentation Rates ofDeep-Sea Fans
5.4.6 Deep-Sea Channels
5.4.7 Summary (Gravity Mass Flows, Turbidites,
Deep-Sea Fans)
5.5 Erosion and Redeposition ofDeep-Sea Sediments 235
5.5.1 Deep Bottom-Current Erosion
5.5.2 Contourites and Sediment Drifts
5.5.3 Stratigraphic Gaps in the Deep-Sea Record
5.5.4 Summary (Deep-Marine Erosion and
Redeposition)
5.6 Paleoceanogrgphy
238
5.6.1 Introduction
5.6.2 Processes Influencing Climate, Ocean
Circulation, and Marine Sediments
Solar Radiation and Feedback Systems
Greenhouse Gases
Air-Sea CO2 Exchange: the Solution Pump and
the Biological Pump
Further Air-Sea-Land Interactions
5.6.3 The Conveyer Belt in the Modem Oceans
5.6.4 Effects ofLow Sea Level
5.6.5 Oceanic Gateways and Paleo-Ocean Circulation
5.6.6 The Cretaceous Ocean
5.6.7 The post-Cretaceous Cooling
5.6.8 Surnrnary (Paleoceanography)