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Paleotopography and deepwater sediment supply : how a Scottish model has been extended across the world

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Paleotopography and deepwater sediment supply : how a Scottish model has been extended across the world
Palaeotopography and deepwater sediment
supply : how a Scottish model has been
extended across the world
Duncan Macgregor
Order of Presentation
Sediment Supply Controls and Prediction of
Palaeotopography
Case Study : Palaeogene Uplift of Scotland
Case Study : Other Atlantic Margin Uplifts
Case Study : The South African Plateau
Regional Integration and Conclusions
Relationships between Topography, Sedimentation and Turbidite
Reservoir Supply
Uplift
Climate (max
rainfall)
Geology/Prov
enance
Eustacy
Vegetation
Erosion Rate Sedimentatio
n Rate Supply of Sand
to Deepwater
Topography
(Slopes)
Accommodation
Shelf-Slope
Topography
onshore offshore
Drainage
(Catchment)
Sorting
Rivers Waves Gravity Currents
Contourites
Controls on Erosion Rates
Geology
Averaged over large regions
Topography
Specifically the development and angle of slopes
Climate
Specifically the maximum intensity of rainfall
Rapid climatic variations increase erosion rates from
Oligocene onwards
Vegetation
Has changed through time
Eustacy
Maximum Sea Level Change <200m so important only on
low relief margins
Hay et al 2002, Allen 1997
Global DEM
Topographic Changes : Tectonic and Non-Tectonic
Lovell 2010
Pliocene uplift , 5My,
Natal
(Partridge 1997)
Messinian dessication
lake level fall
Plio-Pleist uplift , 5My,
Ethiopia
(Gani,2007 )
Oligo-Mio uplift ,
20My, Ethiopia
(Gani,2007 )
Lake Malawi
lake level cycles
1. Pediplanation Surfaces
Dating by onlap, age of
bauxitisation
2. Extrapolation from
Remaining Outliers
e.g. monoclines
section removal on
unconformities
3. Physical Measurements
Well Data : Vitrinite
Reflectance, Sonic Velocities
, section removed
Apatite Fission Track
Analysis, timing/magnitude
of erosion
4. Source to Sink
Relationships
Facies changes
Compacted sedimentary
volumes
Methodologies for Reconstructing Past Topographies
Old Pediplanation Surface
Young
Pediplanation
Surface
Intermediate Pediplanation Surface
Erosion : Old Interval
Erosion : Young Interval
well
Pulsed uplift
1
2
4
3
Model for provision of
East African turbidite
reservoirs through
multiple kilometre-
scale uplifts supported
by :
AFTA
Ro data
Structural dips
Sedimentary
volumes and
rates apportioned
through time
Erosion Estimates Example
Sediment Flux
How Fast Can Topography Go?
0
50
100
150
200
250
300
0 500 1000 1500 2000 2500
Shendi
DEM
Area sq km
Elevation (m)
Red Sea Rift Shoulders
VOLUME
PRESERVED
VOLUME
ERODED in 30My
1500m erosion
Order of Presentation
Sediment Supply Controls
Case Study : Palaeogene Uplift of Scotland
Case Study : Other Atlantic Margin Uplifts
Case Study : The South African Plateau
Regional Integration and Conclusions
Scotland-Shetland Palaeogene Uplift : Summary
Inception : Danian 65 Ma (local?)
Peak : Thanetian-Ypresian 55Ma
End : ? Lutetian 40 Ma
Area of Uplift : 3500km x 1500km
Maximum Transient Uplift : 2000m?
Pulses of transgression/regression : 11
Igneous activity : major
Proposed Causes : Iceland Plume (mantle), Igneous
underplating
References : Jones et al 2001, 2002; Mudge and Jones, 2004;
Saunders et al 2007; Shaw Champion et al 2008, Lovell 2010;
Rudge et al 2008
Nielsen et al 1986
PALAEOCENE (9.7My) EOCENE (21.9 My)
OLIGOCENE (10.9 My) MIOCENE (15.8 My)
North Sea Cenozoic Isopachs
Atlantic Margin Sedimentation Rate and Uplift
Correlation
PRE-TERTIARY NOT ANALYSED
Order of Presentation
Sediment Supply Controls
Case Study : Palaeogene Uplift of Scotland
Case Study : Other Atlantic Margin Uplifts
(POST-DRIFT successions only)
Case Study : The South African Plateau
Regional Integration and Conclusions
Yo-Yo Tectonics : Altitudes of Uplifted Planation Surfaces (Plateaux)
Surfaces can be assumed to be cut at low relief or angle
Hinterland highs have been repeatedly uplifted
Cyclicity evident
Increase in such uplifts in Oligocene-Recent
Not related to plate separations
Elevated Plateaux : Norway
Japsen et al 2001
Sedimentation Rates, Central Atlantic Conjugate Basins
Uplift Phases : AFTA Data, Central Atlantic Conjugate
Margins
Uplift episode
Uplift episode
Slow or no erosion
Deg C of samples now at surface
Fission track limits
Correlation in Cenozoic but
? not in Cretaceous
- But NW Africa database
very poor, further work
required
Example of South Atlantic Correlation
Fourtanier & Seyve 2001
Winter/Petrobras 2008
South Atlantic Sedimentation Rate and Uplift
Correlation
Progradation Trends Through Time
ORANGE
KWANZA
CONGO Anka early fan sediment starvation *Girassol
GABON condensed
NIGER
SANTOS south only
CAMPOS 22Ma pulse Campos
ESP SANTO
CAMAMU ??
SERGIPE-ALAGOAS
C S
AGE
Pl-Pl
Albian
Cen
Tur
Camp
Maas
Pal
Olig
E Mio
M Mi
L Mio
10
110
100
90
80
70
60
50
40
30
20
WEST AFRICA
BRAZIL
Correlative Uplift Phases : AFTA Data, South Atlantic
Temperature (deg C)
Depth (m)
Uplift episode
Uplift episode
questionable uplift and
subsidence episode Slow or no erosion
Order of Presentation
Sediment Supply Controls
Case Study : Palaeogene Uplift of Scotland
Case Study : Other Atlantic Margin Uplifts
Case Study : The South African Plateau
Regional Integration and Conclusions
South African Plateau
Elevated Plateaux : South Africa
3300m
1100m
South African Plateau Surfaces
Pediplanation Surfaces and Neogene Drainage
Modified after King, 1962
NE BRAZIL NOT COVERED
Preserved uplifted surfaces
(plateaux) are a feature of
Africa (and many other
continents)
Surfaces must have been cut
at low altitudes and/or dips
Smooth African (~Eo-Olig)
surface is best developed
Can reconstruct relief on this
surface to calculated eroded
volumes
Degree of preservation of the
surface is an indicator of
degree of erosion low in
southern Africa
Near equivalent surfaces in
South America
YOUNG
OLD
Mio-Oligocene Late Cret
Early Cret Late Jur
Permian
Age of highs Basement highs DO NOT
date to the age of the Basment
Constrains interpretations of uplift,
denudation rate and timing, can be
related to supply of main reserve
bearing turbidite sands
Outcrop AFTA Ages
(approx timing of burial 3km greater than Present Day)
80-84Ma Late Cretaceous : Topography and
Sedimentation Rate
Axis of S African uplift and
drainage divide moves north
(Moore 2009)
Close to AFTA peaks in both S
African plateau and East Africa.
Drainage divide well established
Zambezi, Rovuma, Rufuji, Lamu,
Orange all major depocentres
draining highs
Moderate sedimentation rates on
Transform Margin/Gabon ,
sediment starved in other West
African and North African coasts
Ill defined uplifts Senegal to Benin
Turbidite reservoirs Ghana
(Turonian), Gabon etc + Brazil,
Senegal?
Legend
spreadingridges
!! !! continentoceanboundary
extensional fault
compressional fault
major transforms
volcanics
#afta points
topography
extreme
high
mod
vhigh
sedimentation rates m/Ma
0-10
10-20
20-40
40-80
80-160
160-320
320-640
palaeolatitudes
!! !! climate line
*bauxites
Fevaporites
lakes
land
transgressed cont. plate
oceanic
continent
Legend
spreadingridges
!! !! continentoceanboundary
extensional fault
compressional fault
major transforms
volcanics
#afta points
topography
extreme
high
mod
vhigh
sedimentation rates m/Ma
0-10
10-20
20-40
40-80
80-160
160-320
320-640
palaeolatitudes
!! !! climate line
*bauxites
Fevaporites
lakes
land
transgressed cont. plate
oceanic
continent
ARID
WARM TEMPERATE
TROPICAL
ARID
Magnitude of South African Neogene Uplift
Recent Climatic and Topographic Controls on Sediment
Supply
Sedimentation Rates
(fully compacted m/Ma)
Uplift
Rift Shoulder
Orogenic
Inherited High
Topography
AFTA Interpreted
Denudation
Evaporite (arid)
+
X
Bauxite (humid)
Laterite (humid)
Change Humid to Arid
Change Arid to
Mediterranean
T known turbidite reservoirs
P progradation
A aggradation
U unconformity tilting to continent
volcanics
land
Topography
0-500m
500-1000m
1000-2000m
>2000m
ARID
ARID
HUMID
SEASONALLY WET
Limit of sign run-off
Mantle Low Velocity Zones
Adams et al 2012, Brandt 2012
Order of Presentation
Sediment Supply Controls
Case Study : Palaeogene Uplift of Scotland
Case Study : Other Atlantic Margin Uplifts
Case Study : The South African Plateau
Regional Integration and Conclusions
Turbidite Reserves vs Sedimentation Rate
Reserves
>5000MMBOE
Campos (
Olig)
Central
North
Sea Palaeocene
Angola (Mio)
Niger (Mio)
Reserves
1000
-5000
MMBOE
Campos (
Sant-
Maas,
Eo)
Ghana (
Cen-
Con)
N Gabon (
Sant-
Maas)
Angola (
Olig)
Campos (Mio)
Santos (
Sant-
Maas)
WoS
(Palaeocene)
Niger (
Plio)
Reserves 100
-
1000 MMBOE
Rio Muni (
Sant-
Maas)
Santos
(Eo,
Olig
)
Niger (E Mio)
Liberia (Late K)
No Discoveries
to date
(examples)
Most
Palaeogene
sections
in W
Africa, Angola
(Late K)
Niger (pre
-
Mio,Akata
Sh)
Sed
Rate 0-
20m/Ma
Sed
Rate 20-
50m/Ma
Sed
Rate 50-
300m/Ma
Sed
Rate over
300m/Ma
Sandy
systems
Muddy
systems
Early Cretaceous
Legend
sedimentation rate
m/Ma fully compacted
1-10
10-20
20-40
40-80
80-160
160-320
high areas
palaeoland
Hydrocarbons in
turbidites
Plate Tectonics : gplates
Shorelines : Smith et al,
1994
Climate : Morley (2007),
Scotese (2011)
Not analysed
Late Cretaceous
Legend
sedimentation rate
m/Ma fully compacted
1-10
10-20
20-40
40-80
80-160
160-320
high areas
palaeoland
Plate Tectonics : gplates
Shorelines : Smith et al,
1994
Climate : Morley (2007),
Scotese (2011)
Hydrocarbons in
turbidites
Rift Shoulders :
Sed Rates not analysed
Chalk Domain
Eocene
Legend
sedimentation rate
m/Ma fully compacted
1-10
10-20
20-40
40-80
80-160
160-320
high areas
palaeoland
Plate Tectonics : gplates
Shorelines : Smith et al,
1994
Climate : Morley (2007),
Scotese (2011)
Hydrocarbons in
turbidites
Early Miocene
Legend
sedimentation rate
m/Ma fully compacted
1-10
10-20
20-40
40-80
80-160
160-320
high areas
palaeoland
Plate Tectonics : gplates
Shorelines : Smith et al,
1994
Climate : Morley (2007),
Scotese (2011)
Hydrocarbons in
turbidites
Summary of Continental Margin Uplifts, Periods of High
Sedimentation Rates and Turbidite Reservoirs
SOUTH ATLANTIC CENTRAL ATLANTIC NORTH ATLANTIC
TRANSFORM
MARGINS
WE W E W E
breakup breakup
breakup
breakup
hydrocarbons in turbidite reservoirs
continental margin uplifts
high marginal sedimentation rates
Amazon
Niger
(distal
effects)
?
??
transform
??
?
?Atlas
minor Pre-Tertiary /
Pre-Drift
not analysed
Conclusions
Uplift (in tandem with climate) is the key control on sediment
supply to marginal and rift/sag basins
Topographies have changed dramatically through time and are
generally short lived
Multiple causes of palaeo- and past-topographies, tendency for
conjugate margins to correlate
Depositional environment and reservoir maps need to be based on
palaeo-topographies. A Basement High may be a young feature.
Petroleum systems implications : Key in understanding both the
uplift history of onshore source rocks and the sediment supply to
marginal basins
Rates of sediment supply help predict deepwater reservoir
occurrences
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