1

Week 2

Review of week 1o class project

o reserve reading

Tectonic setting of sedimentary basins

Basin analysis exampleo Gulf of Suez Rift Basin (Alsharhan, 2003; Lindquist, 1998)

Tectonic setting of sedimentary basins (continued)

2

Review of week 1

Course objectives and scope

Petroleum geology and basin analysiso class project

Plate tectonics and basin formation

3

Course Schedule and ContentClass Topic

Sept 14

Week 1

Introduction to Course and Material

Review and discussion of concepts

Sept 21

Week 2

Example of basin analysis: Gulf of Suez Rift Basin

Basins I: description of basins, plate tectonics, basin classification and

tectonic setting

Sept 28

Week 3

Basins II: basin classification (continued), basin models of subsidence

and sedimentation

Oct 5

Week 4

Basin Fill I: Stratigraphy and sedimentology; tools used, dating and

correlation

Oct 12

Week 5

Basin Fill II: Facies models, basin mapping; sequence s tratigraphy

Oct 19

Week 6

Basin Fill III: Sequence stratigraphy (continued), seismic stratigraphy

Oct 26

Week 7

Due Today: Selection of basin/petroleum system for main class

project

Basins III: Regional and global stratigraphic cycles

Nov 2

Week 8

Mid Term Exam (tentative)

Review selected basin example

Nov 9

Week 9

Petroleum System I: The petroleum system

Nov 16

Week 10

Student seminars

Petroleum System II: Field size distribution, play concepts

Nov 23

Week 11

Student seminars

Selected geologic topic: Carbonate models: basin fill and sequence

stratigraphy

Nov 30

Week 12

Student seminars

Carbonate models (continued): sequence stratigraphy, reservoir

development

Dec 7

Week 13

Student seminars

Basin modeling software demonstration

4

What is Basin Analysis

Basin analysis involves making an interpretation of the formation, evolution, architecture and fill of a sedimentary basin by examining geological variables associated with the basin.

Basin analysis provides a foundation for extrapolating known information into unknown regions in order to predict the nature of the basin where evidence is not available.

A basin model is built on a framework of geological surfaces that are correlated within the basin. This stratigraphic framework can be expressed in terms of rock type (lithostratigraphy), fossil content (biostratigraphy), age (chronostratigraphy), or rock properties such as seismic velocity (seismic stratigraphy).

5

(after Mial, 2000)Methods of

AnalysisGlobal Stratigraphic

Hierarchy

magnetic reversalsearthquake first

motions

deep seismicregional stratigraphy

biogeography

basin modelsbackstripping

geohistory analysis

radiometric datingpaleontology

sequence stratigraphy

seismic stratigraphyseismic facies

regional well datalithofacies analysis

paleocurrent analysis

sequence analysis

analysis of core or outcrop

sea floor spreading

plate positioneustatic sea level

plate and terrane interaction

plate margin typebasin generation

unconformity bounded stratigraphic sequences

depositional systems tracts

depositional systems

lithofacies assemblage

individual lithofaciessmall scale

large scale

6

Geoscience Effort in Basin Analysis

Basin analysis for exploration can be described as the integration of the following 3 components

Controls on development of the sedimentary basinplate tectonic and paleogeographic history

Stratigraphy and sedimentology of the basinbasin fill

The petroleum systemsource, maturity, migration, trap, seal

Significant geoscience effort is required to prepare each of these components of the basin analysis; multidisciplinary approach

7

Class project

Selection of basin/petroleum system for main class project by October 26

o select basin and petroleum system and have prepared references

o references required in standard format; AAPG

o only one student per basin/petroleum system; first come - first served

Integrate the 3 components of basin analysis for petroleum exploration through research of publicly available information (journals, books, government publications)

1. Controls on development of the sedimentary basin; plate tectonic and paleogeographic history

2. Stratigraphy and sedimentology of the basin; basin fill

3. The petroleum system; source, maturity, migration, trap, seal

Present paper to class according to schedule

Written paper due no later than Dec 14

8

Class project continued

Source of information and references to begin:o USGS website

o summary spreadsheet provided by Dr. McNamara

Desktop/Basin Analysis/world hydrocarbon volumes.xls

Reserve reading: Gallagher library material

9

Tectonic Basin Classification

(Einsele, 2000, Table 1.1)

10

Plate Tectonic Model

(http://pubs.usgs.gov/publications/text/Vigil.html)

11

Crustal Hotspots

(http://pubs.usgs.gov/publications/text/world_map.html)

12

Basin types: example tectonic setting

(Einsele, 2000, Ch 1)

13

Tectonics and Sediment Fill

(Einsele, 2000, Fig 1.5)

14

Isostasy

The state of gravitational equilibrium between the

lithosphere and the asthenosphere of the Earth such

that lithospheric plates "float" at a given elevation

depending on their thickness. The balance between the

elevation of the lithospheric plates and the

asthenosphere is achieved by the flowage of the

denser asthenosphere.

(http://www.glossary.oilfield.slb.com)

15

Case Study: Gulf of Suez Rift Basin

Alsharhan, A.S., 2003. Petroleum geology and potential

hydrocarbon plays in the Gulf of Suez rift basin, Egypt:

Am. Assoc. Petroleum Geol. Bull., v. 87, p. 143-180.

The 3 components of basin analysis

o tectonic and paleogeographic setting

o basin fill

o petroleum system

16

Basin analysis by Alsharhan, A.S., 2003

Geographic setting

Lithostratigraphy

o Prerift, synrift, postrift

Tectonic development

o rifting and subsidence, deep troughs

Petroleum System

o heat flow

o maturation

o organic content

Hydrocarbon Traps

17

Geography, Surface Geology, Oil Fields

Gulf of Suez

30 to 80 km wide

320 km long

40-60m water depth

240 discoveries

80 fields

1000 exploration wells

18

Basin Analysis

The specific tools used in this basin analysiso Lithostratigraphic units

o stratigraphy: measured stratigraphic sections, subsurface cores, electric

logs

o age: electric logs tied to microfaunal and palynological studies of ditch

samples; pollen and spores used to date Paleozoic-L. Cret Nubian

sandstone

o plate tectonics

o eustatic sea level curves

o subsidence rates

o heat flow

o source rock maturity- TOC, Ro, Van Krevelen

What has not been included?

19

Integrated Tectonics, Sedimentation, Sea Level

20

Evolution of Gulf of Suez Basin: Paleozoic

Deposition of Paleozoic terrestrial clastics over Precambrian crystalline basement;

significant periods of uplift and unconformity

21

Permian-Triassic (Prerift)

Local subsidence, minor transgression; fluvial and marine shales and sandstones

22

Early Cretaceous (Synrift)

Rifting, graben system via block faulting, depressions filled with non-marine

sandstone and shale

23

Middle Cretaceous to Miocene (Synrift)

Normal faulting, subsidence of graben system, marine incursion; marine sandstones

and limestones; capped by thick salt deposits

24

Pliocene-Holocene (Postrift)

Basin margins uplifted, non-marine sand wedge fills marine basin area

25

Note interbedded

source, reservoir and

seal lithologies

26

Synrift Lithostratigraphic Units

27

Geothermal Gradient and Hot Spot Areas

28

Hydrocarbon Traps and Trapping Mechanism

29

Total Organic Content (weight %)

30

Source Areas and Migration Paths

31

Traps and Seals

32

Conclusion: Gulf of Suez Rift Basin

Integrated picture covering differing geoscience

disciplines

Simple basin geohistory, basin fill, petroleum system

covered

Missing: seismic facies, sequence stratigraphy, cross

sections, well logs, subsidence model, quantitative

backstripping

some of these may be covered in reference material

33

(after Miall, 2000)Methods of

AnalysisGlobal Stratigraphic

Hierarchy

magnetic reversalsearthquake first

motions

deep seismicregional stratigraphy

biogeography

basin modelsbackstripping

geohistory analysis

radiometric datingpaleontology

sequence stratigraphy

seismic stratigraphyseismic facies

regional well datalithofacies analysis

paleocurrent analysis

sequence analysis

analysis of core or outcrop

sea floor spreading

plate positioneustatic sea level

plate and terrane interaction

plate margin typebasin generation

unconformity bounded stratigraphic sequences

depositional systems tracts

depositional systems

lithofacies assemblage

individual lithofaciessmall scale

large scale

34

Tectonics: Principles, Models and Cycles

Basin modelso basin formation

o The “Wilson Cycle”

o classification system and examples

Tectonism and Sedimentationo components of basin models

o extensional basins

o supracrustal loading

o basement tectonics

35

Basin Forming Processes

Crustal Stress Environmentso extensional (extensional basins)

o contractional (convergent, compressional basins)

o shear (pull-apart basins)

Extension:o heating of the lithosphere from below

o thinning of crust

o stretching of crust

Convergence:o local loading with accompanying subsidence due to stacking of thrust

slices/nappes

36

Three Principal Stress Environments Under Which Sedimentary Basins Are Produced

(Miall, 2000, Fig 7.1)

37

Plate Boundaries

38

Thickness of Continental Crust From Seismic Velocity

(Allen and Allen, 1990, Fig 1.3)

(values in km/s); 8.1 km/s marks base of

crust)

39

Mechanisms of Basin Subsidence

Thermal cooling and

subsidence

Changes in

crustal/lithospheric thickness:

thinning of crust followed by

faulting, subsidence

Loading to cause deflection or

flexural deformation

(Allen and Allen, 1990, Fig 1.12)

40

The Wilson Cycle (handout)

The cycle of opening and closing of ocean basinso Oceanic crust cools as it ages, becoming more dense and

gravitationally unstable with respect to substratum – oceanic crust gets

consumed

References:o Wilson, J. T., 1966, Did the Atlantic close and then re-open?, Nature,

211(5050), 676-681

o Ancient Environments and the Interpretation of Geologic History, by

Lynn S. Fichter and David J. Poche, 3rd edition, 2001, Prentice Hall

41

The “Wilson Cycle”

42

Basin Models and Classification

There are 6 major basin typeso oceanic basins

o rifted continental margins

o arc-trench systems

o suture belts

o intracontinental basins

o strike-slip or transform related basins

These have been classified in different ways by

different authors.

Classification systemso Einsele (2000), Chapter 1

o Miall (2000), Chapter 9

o Allen and Allen (1990), Chapter 1

43

Basin Models and Classification

Sedimentary basins classified in terms of 3 criteria:o 1. the type of crust on which the basin rests (continental, oceanic,

transitional)

o 2. the position of the basin relative to plate margins (within plate or

margin of plate)

o 3. where the basin lies close to a plate margin, the type of plate

interaction occurring during sedimentation (divergent, convergent,

transform)

44

Basin Classification System (Einsele, 2000)

1 32

45

Basin Category: Continental Interior

Continental or interior sag basins

Continental or interior fracture basins

46

Continuum: Sags to Passive Margins

(Allen and Allen, 1990, Fig 3.31)

47

Basin Category: Passive Margin, Oceanic Sag

Passive Margin

Oceanic Sag and Fault Bounded Basins

48

Basin Category: Subduction Related

49

Basin Category: Collision Related

50

Strike-slip Basins

Strike-slip basins can occur:o oceanic and continental transforms

o continental extension undergoing rifting

o convergent plate boundaries of orogenic belts

Basins associated with strike-slip deformation are

generally small and complex compared to rifts,

passive margins and foreland basins.

Lateral movement takes place between adjacent

crustal or lithospheric blocks

Movement is rarely pure lateral; usually oblique

51

Transform and Transcurrent Faults

transform fault: strike slip fault that is deep seated and

between plates (interplate); plate boundary fault

system linking other boundary types; boundary

parallel movement o examples: ocean ridge transform faults, plate boundary transform faults,

trench linked strike-slip faults

transcurrent fault: strike slip fault that is confined to

the crust and within a plate (intraplate) (Allen and

Allen, 1990, p 116)o examples: indent linked faults bounding continental blocks in collision

zone; intracontinental strike-slip faults separating terranes of differing

tectonic styles

52

Classification of Strike-slip Faults

(Allen and Allen, 1990, Table 5.2)

53

Strike-slip Faults

transcurrent fault

(Allen and Allen, 1990, Fig 5.2)

54

Basin Category: Strike-slip

55

Basin Classification System (Miall, Ch 9)

1. Divergent Margin Basins1. rift basins

2. ocean margin rises and terraces

3. aulacogens and failed rifts

2. Convergent Margin Basins1. trenches and subduction complexes

2. forearc, intra-arc, backarc, foreland, satellite basins

3. Transform and transcurrent-fault basins1. basins in braided fault systems (wrench complexes)

2. fault termination basins

3. pull apart basins

4. transrotational basins

56

Basin Classification System (continued)

4. Basins developed during continental collision and

suturing1. peripheral basins on downgoing plate

2. remnant ocean basins

3. hinterland foreland, strike-slip and graben basins; intermontane basins

5. Intraplate basins1. cratonic basins floored by continental crust

2. oceanic islands, sea mounts, plateaus floored by oceanic crust

57

Basin Classification (Kingston et al, 1983)

(Allen and Allen, 1990, Table 1.11)

58

Use of Basin Classification Systems

Basin models represent prototypes of tectonically

controlled basins; every basin will differ from these

models

There are no type basins which can be used as a model for

any other basin

Within a single, broad tectonic setting the development of

basins will exhibit great variation

Over time, sedimentary basins evolve from one type to

another, further complicating sedimentary and tectonic

history

Tectonic classification of a basin may have no bearing on

petroleum potential of the basin

59

Basin Classification: Summary

Reviewed common classification systems as presented

in Miall (2000), Einsele (2000) and Allen and Allen

(1990).

Sedimentary basins classified in terms of 3 criteria:o 1. the type of crust on which the basin rests (continental, oceanic,

transitional)

o 2. the position of the basin relative to plate margins (within plate or

margin of plate)

o 3. where the basin lies close to a plate margin, the type of plate

interaction occurring during sedimentation (divergent, convergent,

transform)

60

1st and 2nd Order Cycles of Sea Level Change

(Vail et al, 1977)