understanding earth sixth edition chapter 5: sedimentation: rocks formed by surface processes ©...

Understanding EarthSixth Edition

Chapter 5:SEDIMENTATION:

Rocks Formed by Surface Processes

© 2011 by W. H. Freeman and Company

Grotzinger • Jordan

Chapter 5Chapter 5

Sedimentation:Sedimentation:Rocks Formed by Rocks Formed by

Surface ProcessesSurface Processes

About SedimentationAbout Sedimentation

• Sediments are produced on the Earth’s Sediments are produced on the Earth’s surface as a result of weathering.surface as a result of weathering.

• Sediments are transported and become Sediments are transported and become sedimentary rocks after they come to sedimentary rocks after they come to

rest. rest.

• Sedimentary rocks give evidence of Sedimentary rocks give evidence of ancient sedimentary environments where ancient sedimentary environments where

they formed.they formed.

Lecture OutlineLecture Outline

1.1. Surface processes of the rock cycleSurface processes of the rock cycle

2. Sedimentary basins: the sinks for 2. Sedimentary basins: the sinks for sedimentssediments

3. Sedimentary environments3. Sedimentary environments

4. Sedimentary structures4. Sedimentary structures

5. Burial and diagenesis: from sediment to 5. Burial and diagenesis: from sediment to rockrock

Lecture OutlineLecture Outline

6. Classification of siliciclastic sediments 6. Classification of siliciclastic sediments and sedimentary rocksand sedimentary rocks

7. Classification of chemical and biological 7. Classification of chemical and biological sediments and sedimentary rockssediments and sedimentary rocks

1. Surface Processes and the Rock Cycleurface Processes and the Rock Cycle

WeatheringWeathering

Physical weatheringPhysical weathering

Chemical weatheringChemical weathering

1. Surface Processes and the Rock CycleSurface Processes and the Rock Cycle

Processes forming sedimentary rock:Processes forming sedimentary rock:

WeatheringWeatheringErosionErosionTransportationTransportationDeposition (sedimentation)Deposition (sedimentation)Burial and compactionBurial and compactionDiagenesisDiagenesis


Classification of sedimentsClassification of sediments

Siliciclastic sedimentsSiliciclastic sediments

Chemical sedimentsChemical sediments

Biological sedimentsBiological sediments


Current strength and distance of Current strength and distance of transport affect:transport affect:

Size of clastic particlesSize of clastic particles

Sorting of clastic particlesSorting of clastic particles

Rounding of clastic particlesRounding of clastic particles


Chemical mixing vats:Chemical mixing vats:

OceansOceans

LakesLakes

Thought questions for this chapterThought questions for this chapter

A geologist is heard to say that a particular sandstone A geologist is heard to say that a particular sandstone was derived from a granite. What information could she was derived from a granite. What information could she have gleaned from the sandstone to support this?have gleaned from the sandstone to support this?

Weathering of the continents has been much more Weathering of the continents has been much more widespread and intense in the past 10 million years than it widespread and intense in the past 10 million years than it was in earlier times. How might this be borne out in the was in earlier times. How might this be borne out in the sediments that now cover Earth’s surface?sediments that now cover Earth’s surface?

Describe the beach sands that you would expect to be Describe the beach sands that you would expect to be produced by the beating of waves on a coastal mountain produced by the beating of waves on a coastal mountain range consisting largely of basalt.range consisting largely of basalt.

2.2. Sedimentary BasinsSedimentary Basins

Sediments tend to accumulate in Sediments tend to accumulate in depressions in the Earth’s crust.depressions in the Earth’s crust.

Depressions are formed by Depressions are formed by subsidence.subsidence.

Sedimentary basins are depressions Sedimentary basins are depressions filled with thick accumulations of filled with thick accumulations of sediment. They are sinks for sediment. They are sinks for sediment.sediment.

2.2. Sedimentary BasinsSedimentary Basins

Types of sedimentary basins:Types of sedimentary basins:

Rift basins and thermal Rift basins and thermal subsidence basinssubsidence basins

Flexural basinsFlexural basins

Sedimentary basinsSedimentary basinsform on riftedform on riftedcontinental continental marginsmargins

3.3. Sedimentary EnvironmentsSedimentary Environments

Types of environments:Types of environments:

1. Continental1. ContinentalLakeLakeAlluvialAlluvialDesertDesertGlacierGlacier



2. Shoreline2. ShorelineDeltaDeltaBeachBeachTidal flatsTidal flats



3. Marine3. MarineDeep seaDeep seaContinental shelfContinental shelfOrganic reefOrganic reefContinental marginContinental marginContinental slope Continental slope

and slopeand slope

SedimentarySedimentaryEnvironmentsEnvironments


Environments of siliciclastic Environments of siliciclastic sediments:sediments:

Continental (alluvial, desert, Continental (alluvial, desert, lake, and glacial)lake, and glacial)

Shoreline (deltas, beaches, Shoreline (deltas, beaches, and tidal flats)and tidal flats)

Marine (shelf, margin, slope, Marine (shelf, margin, slope, and deep sea)and deep sea)

3.3. Sedimentary Environmentsedimentary Environments

Environments of chemical and Environments of chemical and biological sediments:biological sediments:

Carbonate deposits (organic Carbonate deposits (organic reefs, beaches, shelves, reefs, beaches, shelves, and tidal flats)and tidal flats)

Siliceous environments (deep Siliceous environments (deep sea)sea)

Evaporite environments (lakes)Evaporite environments (lakes)


From the base upward, a bedding sequence begins with a From the base upward, a bedding sequence begins with a bioclastic limestone, passes upward into a dense bioclastic limestone, passes upward into a dense carbonate rock made of carbonate-cementing organisms, carbonate rock made of carbonate-cementing organisms, and ends with beds of dolostone. Deduce the possible and ends with beds of dolostone. Deduce the possible sedimentary environments represented by this sequence.sedimentary environments represented by this sequence.

In what sedimentary environment are carbonate muds?In what sedimentary environment are carbonate muds?

How can you use size and sorting of sediments to How can you use size and sorting of sediments to distinguish between sediments deposited in a glacial distinguish between sediments deposited in a glacial environment and those deposited in a desert?environment and those deposited in a desert?

Where are reefs likely to be found?Where are reefs likely to be found?

4. Sedimentary Structures4. Sedimentary Structures

Sedimentary structures – all kinds Sedimentary structures – all kinds of features in sediments formed at of features in sediments formed at the time of deposition.the time of deposition.

Bedding (stratification)Bedding (stratification)Cross-beddingCross-beddingGraded beddingGraded beddingRipplesRipplesBioturbation structuresBioturbation structures

Cross-Cross-beddingbedding

Ripples – modern and ancientRipples – modern and ancient

Bioturbation StructuresBioturbation Structures

4. Sedimentary Structures4. Sedimentary Structures

Bedding sequences – vertically Bedding sequences – vertically stacked layers of sedimentary rock stacked layers of sedimentary rock with different types of sedimentary with different types of sedimentary structures in each layer.structures in each layer.

Example of a Bedding SequenceExample of a Bedding Sequence


You are looking at a cross section of rippled sandstone. You are looking at a cross section of rippled sandstone. What sedimentary structure would tell you the direction of What sedimentary structure would tell you the direction of current that deposited the sand?current that deposited the sand?

You discover a bedding sequence that has a You discover a bedding sequence that has a conglomerate at the base; grades upward into sandstone conglomerate at the base; grades upward into sandstone and then to a shale; and finally, at the top, grades to a and then to a shale; and finally, at the top, grades to a limestone. What changes in the sediment source area limestone. What changes in the sediment source area would have been responsible for this sequence?would have been responsible for this sequence?

5. Burial and Diagenesis5. Burial and Diagenesis

Burial is the preservation of Burial is the preservation of sediments within a sedimentary sediments within a sedimentary basin. basin.

Diagenesis is the physical and Diagenesis is the physical and chemical change that converts chemical change that converts sediments to sedimentary rocks.sediments to sedimentary rocks.

5. Burial and Diagenesis5. Burial and Diagenesis

Lithification includes:Lithification includes:

CompactionCompaction

CementationCementation


If you drilled one oil well into the bottom of a sedimentary If you drilled one oil well into the bottom of a sedimentary basin that is 1 km deep and another that is 5 km deep, basin that is 1 km deep and another that is 5 km deep, which would have the higher pressures and which would have the higher pressures and temperatures? Oil turns into natural gas at high basin temperatures? Oil turns into natural gas at high basin temperatures. In which well would you expect to find temperatures. In which well would you expect to find more natural gas?more natural gas?

6. Classification of Siliciclastic Sediments6. Classification of Siliciclastic Sedimentsand Sedimentary Rocksand Sedimentary Rocks

Classification of sediments by Classification of sediments by particle sizeparticle size

Classification of sedimentary Classification of sedimentary rocks by texture and compositionrocks by texture and composition


Four major compositional groups Four major compositional groups of siliciclastic sediments:of siliciclastic sediments:

ArkoseArkoseLithicLithicQuartz areniteQuartz areniteGraywackeGraywacke

7. Classification of Chemical 7. Classification of Chemical and Biological Sediments, and Biological Sediments,

Sedimentary RocksSedimentary Rocks

Chemical sedimentary rocksChemical sedimentary rocksLimestoneLimestoneChertChertOrganicsOrganicsPhosphoritePhosphorite


Sedimentary rocksSedimentary rocks

Biological sedimentary rocksBiological sedimentary rocksDolostoneDolostoneIron formationIron formationEvaporiteEvaporite

Organic Reef DevelopmentOrganic Reef Development

Organic Reef RockOrganic Reef Rock

7. Classification of Chemical7. Classification of Chemical and Biological Sediments, and Biological Sediments,


Carbonate sediments and rocksCarbonate sediments and rocks

Evaporite sediments and rocksEvaporite sediments and rocks

Other sediments and rocksOther sediments and rocks



Carbonate sediments and rocksCarbonate sediments and rocks

LimestonesLimestonesDolostonesDolostones



Evaporite sediments and rocksEvaporite sediments and rocks

MarineMarineNon-marineNon-marine



Other sediments and rocksOther sediments and rocks

SiliceousSiliceousPhosphoritePhosphoriteIron oxideIron oxideCoal and peatCoal and peat


What role do organisms play in the origin of some types What role do organisms play in the origin of some types of limestone?of limestone?

A bay is separated from the open ocean by a narrow, A bay is separated from the open ocean by a narrow, shallow inlet. What kind of sediment would you expect to shallow inlet. What kind of sediment would you expect to find on the floor of the bay if the climate were warm and find on the floor of the bay if the climate were warm and arid? What kind of sediment would you find if the climate arid? What kind of sediment would you find if the climate were cool and humid?were cool and humid?

How are chert and limestone similar in origin? Discuss How are chert and limestone similar in origin? Discuss the roles of biological versus chemical processes.the roles of biological versus chemical processes.

ArkoseArkoseBedding sequenceBedding sequenceBioclastic sedimentBioclastic sedimentBiological sedimentBiological sedimentBioturbationBioturbationCarbonate rockCarbonate rockCarbonate sedimentCarbonate sedimentCementationCementationChemical sedimentChemical sedimentChemical weatheringChemical weatheringChertChertClay Clay ClaystoneClaystoneCoalCoalCompactionCompaction

Key terms and conceptsKey terms and concepts

ConglomerateConglomerateContinental shelfContinental shelfCross-beddingCross-beddingCrude oilCrude oilDiagenesisDiagenesisDolostoneDolostoneEvaporite rockEvaporite rockEvaporite sedimentEvaporite sedimentFlexural basinFlexural basinForaminiferaForaminiferaGraded beddingGraded beddingGravelGravelGraywackeGraywackeIron formationIron formationLimestoneLimestone


Lithic sandstoneLithic sandstoneLithificationLithificationMud Mud MudstoneMudstoneNatural gasNatural gasOilOilOrganic sedimentary rockOrganic sedimentary rockPeatPeatPhosphoritePhosphoritePhysical weatheringPhysical weatheringPorosityPorosityQuartz areniteQuartz areniteReefReefRift basinRift basinRippleRipple


SalinitySalinitySandSandSandstoneSandstoneSedimentary basinSedimentary basinSedimentary environmentSedimentary environmentSedimentary structureSedimentary structureShaleShaleSiliciclastic sedimentsSiliciclastic sedimentsSilt Silt SiltstoneSiltstoneSortingSortingSubsidenceSubsidenceTerrigenous sedimentTerrigenous sedimentThermal subsidence basinThermal subsidence basin


understanding earth sixth edition chapter 5: sedimentation: rocks formed by surface processes ©...

Documents

sedimentary rocks7

sedimentary basinssediments

sedimentary environments4

sedimentary structures5

sedimentary environments3

rock cycle surface processes

earths surface

rock cycleprocesses