ge0-3112 sedimentary processes and products lecture 13. sequence stratigraphy geoff corner...
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GE0-3112GE0-3112 Sedimentary processes and products Sedimentary processes and products
Lecture 13. Sequence stratigraphyLecture 13. Sequence stratigraphy
Geoff CornerGeoff CornerDepartment of GeologyDepartment of GeologyUniversity of TromsøUniversity of Tromsø20062006
Literature:Literature:- Leeder 1999. Ch. 14. Changing sea level and - Leeder 1999. Ch. 14. Changing sea level and
sedimentary sequences.sedimentary sequences.- Reading & Levell 1996. Ch. 2. Controls on the - Reading & Levell 1996. Ch. 2. Controls on the
sedimentary rock record.sedimentary rock record.
ContentsContents
►StratigraphyStratigraphy►Why sequence stratigraphy?Why sequence stratigraphy?►ParasequencesParasequences►Systems tractsSystems tracts►Bounding surfacesBounding surfaces
Stratigraphy – the subdivision of Stratigraphy – the subdivision of rocks in time and spacerocks in time and space
► LithostratigraphyLithostratigraphy► BiostratigraphyBiostratigraphy► ChronostratigraphyChronostratigraphy► MagnetostratigraphyMagnetostratigraphy► ChemostratigraphyChemostratigraphy► MorphostratigraphyMorphostratigraphy► ClimatostratigraphyClimatostratigraphy► KinetostratigraphyKinetostratigraphy► TectonostratigraphyTectonostratigraphy► AllostratigraphyAllostratigraphy► Sequence stratigraphySequence stratigraphy
What is sequence What is sequence stratigraphy?stratigraphy?
►Packages of strata deposited during a Packages of strata deposited during a cycle of relative sea-level change cycle of relative sea-level change and/or changing sediment supply.and/or changing sediment supply.
►Genetic/interpretative approach:Genetic/interpretative approach: packages related to relative sea-level packages related to relative sea-level
and/or sediment supply.and/or sediment supply. packages bounded by chronostratigraphic packages bounded by chronostratigraphic
surfaces.surfaces.
Walker 1992
Why use sequence Why use sequence stratigraphy?stratigraphy?
► To To correlate and predictcorrelate and predict facies and facies and unconformities: division of the sedimentary unconformities: division of the sedimentary record into time-related genetic units.record into time-related genetic units.
► To To understand the distribution of sedimentary understand the distribution of sedimentary faciesfacies and unconformities in time and space. and unconformities in time and space.
► To To determine the amplitudes and rates of determine the amplitudes and rates of change of past relative sea-levelchange of past relative sea-level and, in turn, and, in turn, understand the cyclic and non-cyclic nature understand the cyclic and non-cyclic nature of tectonics and climate change (durations of of tectonics and climate change (durations of 10 ka - >50 Ma). 10 ka - >50 Ma).
What criteria do we use?What criteria do we use?
►Stacking patterns - indicate relative Stacking patterns - indicate relative sea-level change and or sediment sea-level change and or sediment supply.supply.
►Bounding surfacesBounding surfaces
Components of a sequenceComponents of a sequence
►Bounding surfacesBounding surfaces Sequence boundarySequence boundary Transgressive surfaceTransgressive surface Maximum flooding surfaceMaximum flooding surface
►Systems tractsSystems tracts LSTLST TSTTST HST/RSTHST/RST
►ParasequencesParasequences
Prothero & Schwab 1996
ParasequencesParasequences
► Parasequences: the small-scale Parasequences: the small-scale building blocks of systems building blocks of systems tracts and sequences.tracts and sequences.
► A parasequence represents a A parasequence represents a proximal to distal change in proximal to distal change in facies accumulated during a facies accumulated during a minor cycle in the balance minor cycle in the balance between sediment supply and between sediment supply and accomodation.accomodation.
► Each parasequence is bounded Each parasequence is bounded above by a above by a flooding surfaceflooding surface..
Flooding surfaces
Prothero & Schwab 1996
Stacking pattern of Stacking pattern of parasequencesparasequences
►ProgradationalProgradational►RetrogradationalRetrogradational►AggradationalAggradational
Prothero & Schwab 1996
SequencesSequences
► A sequence is composed of a succession of A sequence is composed of a succession of parasequence sets.parasequence sets.
► Each sequence represents one major cycle Each sequence represents one major cycle of change in the balance between of change in the balance between accomodation space and sediment.accomodation space and sediment.
► A sequence is subdivided into 3 or 4 A sequence is subdivided into 3 or 4 systems tractssystems tracts, each representing a specific , each representing a specific part of the cycle. part of the cycle.
Prothero & Schwab 1996
Systems tractsSystems tracts►ExxonExxon
LST, TST, HST (incl. RST)LST, TST, HST (incl. RST)
►AlternativeAlternative LST, TST, HST, RST (forced RST) LST, TST, HST, RST (forced RST)
Walker 1992
Lowstand STLowstand ST►Formed immediately following s.l. Formed immediately following s.l.
lowstand.lowstand.►Fluvial incision ceases; progradational to Fluvial incision ceases; progradational to
aggradational marine parasequences aggradational marine parasequences deposited.deposited.
►Active submarine fans below the shelf Active submarine fans below the shelf break.break.
Transgressive STTransgressive ST►Formed during s.l. rise.Formed during s.l. rise.►Accomodation space > sediment supply Accomodation space > sediment supply
retrogradational parasequences.retrogradational parasequences.►Base of TST is the transgressive surface Base of TST is the transgressive surface
(=ravinement erosional surface of shoreface).(=ravinement erosional surface of shoreface).►Top of TST is the maximum flooding surface.Top of TST is the maximum flooding surface.
Highstand STHighstand ST
►Formed during rising and high s.l.Formed during rising and high s.l.►Accomodation = sediment supply Accomodation = sediment supply
aggradational to progradational aggradational to progradational parasequences.parasequences.
Falling stage STFalling stage ST
►Formed during a s.l. fall (forced Formed during a s.l. fall (forced regression).regression).
►(Included in late HST in Exxon system).(Included in late HST in Exxon system).►May be associated with erosion.May be associated with erosion.
Walker 1992
Bounding discontinuitesBounding discontinuites► Sequence boundary (SB) - surface of subaerial erosion Sequence boundary (SB) - surface of subaerial erosion
and its correlative marine surface formed during sea-and its correlative marine surface formed during sea-level fall. Corresponds to base of incised valley in level fall. Corresponds to base of incised valley in proximal areas.proximal areas.
► Transgressive (ravinement) surface (TS) - transgressive Transgressive (ravinement) surface (TS) - transgressive surface of marine (shoreface) erosion.surface of marine (shoreface) erosion.
► Marine flooding surface - surface across which there is Marine flooding surface - surface across which there is evidence of an abrupt increase in water depth (may be evidence of an abrupt increase in water depth (may be used to separate parasequewnces).used to separate parasequewnces).
► Maximum flooding surface (MFS) - surface marking Maximum flooding surface (MFS) - surface marking regional transition from trangression to regression and regional transition from trangression to regression and most landward extent of the shoreline - commonly most landward extent of the shoreline - commonly marked by a condensed section (horizon).marked by a condensed section (horizon).
► Regressive surface of erosion. Regressive surface of erosion. (NB. may be removed by (NB. may be removed by subaerial erosion or subaerial erosion or transgressive surface).transgressive surface).
Prothero & Schwab 1996
Wheeler (time-distance) Wheeler (time-distance) diagramsdiagrams
Prothero & Schwab 1996
Sequence stratigraphy and Sequence stratigraphy and global sea-level cycles global sea-level cycles
► Various orders of global sea-level Various orders of global sea-level change distinguisged:change distinguisged: 1st order (200-400 m.y.), e.g. 1st order (200-400 m.y.), e.g.
lowstand during Permian Pangea. lowstand during Permian Pangea. Controlled by major tectonic Controlled by major tectonic cycles.cycles.
2nd order (10-100 m.y.), e.g. Mid-2nd order (10-100 m.y.), e.g. Mid-Cretaceous highstand. Controlled Cretaceous highstand. Controlled by changes in ocean-ridge by changes in ocean-ridge spreading rate. spreading rate.
► Global correlation of sequences Global correlation of sequences related to eustatic sea-level curves related to eustatic sea-level curves is difficult or impossible due to is difficult or impossible due to local variations in tectonics and local variations in tectonics and sediment supply. Sequence sediment supply. Sequence development is dependent on: 1) development is dependent on: 1) sea level, 2) tectonics, 3) sediment sea level, 2) tectonics, 3) sediment supply. supply.
Walker 1992
An example of sequence An example of sequence stratigraphic subdivision applied to stratigraphic subdivision applied to
fjord-valley fillsfjord-valley fills
Corner, in press
►Deglacial-postglacial transgressive-Deglacial-postglacial transgressive-regressive fillregressive fill
Glaciomarine deposition
A
Outlet glacier
Fjord glacier
Meltwater
B
Valley glacier
Meltwater
Glaciofluvialdelta
Valley glacier
CMeltwater
Marine deposition
Fluvialdelta
RiverD
Fluvial terracing
ERiver
Post
gla
cial
Degla
cial
Corner, in press
Deglacial-postglacial surface
I
IIIc
IVd
IIa
Df
Dv
PMaximum flooding surface
Regressive accretionary surface
Marine limit
I
I
IIIb
IIb
IIdIIc
IVc
Glacial trough
Cross section X - X’
X’X
A
BMarine limit
IVb
1
3 2
IIb
IIc
IIa
I
IVd
IId
Df
Dv
PIIIc
IVc
II
IIIIV
I
DTST (Df)
PRST (P)
DHST (Dv)
Time
Sea
leve
l
Regressive accretionary surface
PDvDf
Postglacial forced regressive (PRST)
Depositional episodes/sequence tracts
Deglacial (fjord glacier) transgressive (DTST)
Deglacial (valley glacier) highstand (DHST)
Bounding surfaces
Fluvial erosion surface
Deltaic erosion surface
Fluvial accretion surface
IV
III
Depositional elements
II
I
Fjord floor
Delta foreset
- Fluvial (P)IVd
Ice-contact (Df)
Glaciofluvial delta foreset (Df/Dv)
- Marine (P)IIc - Prodelta (P)IId
- Glaciomarine (Df/Dv)IIa/IIb
- Delta topset (P)IVc
IIIc - Delta foreset (P)
Terrace top
- Glaciofluvial delta topset (Df/Dv)IVa/IVb
IIIa/IIIb-
Transgressive systems tractTransgressive systems tract
Highstand systems tractHighstand systems tract
Forced-regressive systems tractForced-regressive systems tract
Corner, in press
►TSTTST►HSTHST►RSTRST
Corner, in press
Further readingFurther reading
► Coe (ed.) 2003. The Sedimentary Record of Sea-Coe (ed.) 2003. The Sedimentary Record of Sea-Level Change.Level Change. Well illustrated, modern treatment of sequence Well illustrated, modern treatment of sequence
stratigraphy and depositional successions.stratigraphy and depositional successions.► Emery & Myers 1996. Sequence stratigraphy.Emery & Myers 1996. Sequence stratigraphy.
Similar to above but more dated. Gives background to Similar to above but more dated. Gives background to nomenclature.nomenclature.
► E-learning journal. Sequence stratigraphy.E-learning journal. Sequence stratigraphy.► Walker 1992, in Walker & James (Ch. 1, 'Facies,
Facies Models and Modern Stratigraphic Concepts').► Corner, G.D. (in press, 2006). A transgressive-Corner, G.D. (in press, 2006). A transgressive-
regressive model of fjord-valley fill: stratigraphy, regressive model of fjord-valley fill: stratigraphy, facies and depositional controls. In Dalrymple, R.W., facies and depositional controls. In Dalrymple, R.W., Leckie, D. and Tillman, R.W. (eds.) ‘Incised-Valley Leckie, D. and Tillman, R.W. (eds.) ‘Incised-Valley Systems in Time and Space', SEPM Special Systems in Time and Space', SEPM Special Publication.Publication.
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