Transcript Spasojevic_HoloceneSeaLevel

Ge 112. Geomorphology and Stratigraphy
HOLOCENE SEA-LEVEL CHANGE
Sonja Spasojević
OUTLINE
1. Motivation
2. Sea-level change: processes and time-scales
3. Methodology for defining relative sea-level (RSL)
4. Holocene RSL around the globe
• Barbados, Tahiti, Papua New Guinea
• Scotland
• Caribbean and South America
5. Conclusions
OUTLINE
1. Motivation
2. Sea-level change: processes and time-scales
3. Methodology for defining relative sea-level (RSL)
4. Holocene RSL around the globe
• Barbados, Tahiti, Papua New Guinea
• Scotland
• Caribbean and South America
5. Conclusions
MOTIVATION
 My research interest
 Modeling long-term geodynamic influence on sea-level change
Sea level (m)
Sea level
(m)(m)
height
Sea-level
 How does long-term sea-level change?
400
400
350
350
300
300
250
250
200
200
150
150
100
100
50
50
0
0
80
80
70
70
Pitman
(1978)
Pitman (1978)
60
60
50
50
40
30
40
30
Age (Ma)
Age (million
years BP)
Age (Ma)
Watts&
Steckler (1978)
Watts& Steckler (1978)
Kominz (1983)
Kominz (1983)
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20
10
10
Haq (2005)
Haq (2005)
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0
MOTIVATION
 This presentation:
 How does sea-level changes during Holocene at different locations?
 What are the controlling processes for Holocene sea-level change?
Ge112 class notes
OUTLINE
1. Motivation
2. Sea-level change: processes and time-scales
3. Methodology for defining relative sea-level (RSL)
4. Holocene RSL around the globe
• Barbados, Tahiti, Papua New Guinea
• Scotland
• Caribbean and South America
5. Conclusions
SEA-LEVEL CHANGE: Processes and time-scales
At any location relative sea-level (RSL) change is a result of:
1) Eustatic change
2) Isostatic or tectonic change
3) Local coastal processes
SEA-LEVEL CHANGE: Processes and time-scales
1) Eustatic level (sea-surface) change
 Change in water volume
 Glacial eustasy-ocean and ice volume in balance
 Water expansion/contraction (change of temperature and salinity)
 Change in hydrologic cycle, storage in sediments, etc.
2) Isostatic or tectonic change
3) Local coastal processes
SEA-LEVEL CHANGE: Processes and time-scales
1) Eustatic level (sea-surface) change
 Change in water volume
 Glacial eustasy-ocean and ice volume in balance
 Water expansion/contraction (change of temperature and salinity)
 Change in hydrologic cycle, storage in sediments, etc.
 Change in ocean basin volume
 Tectono-eustasy
 Change of spreading rate- very slow
2) Isostatic or tectonic change
3) Local coastal processes
SEA-LEVEL CHANGE: Processes and time-scales
1) Eustatic level (sea-surface) change
 Change in water volume
 Glacial eustasy-ocean and ice volume in balance
 Water expansion/contraction (change of temperature and salinity)
 Change in hydrologic cycle, storage in sediments, etc.
 Change in ocean basin volume
 Tectono-eustasy
 Change of spreading rate- very slow
 Change of water distribution
 Geoidal isostasy
2) Isostatic or tectonic change
3) Local coastal processes
SEA-LEVEL CHANGE: Processes and time-scales
1) Eustatic level (sea-surface) change
 Change in water volume
 Glacial eustasy-ocean and ice volume in balance
 Water expansion/contraction (change of temperature and salinity)
 Change in hydrologic cycle, storage in sediments, etc.
 Change in ocean basin volume
 Tectono-eustasy
 Change of spreading rate- very slow
 Change of water distribution
 Geoidal isostasy
2) Isostatic or tectonic change
3) Local coastal processes
SEA-LEVEL CHANGE: Processes and time-scales
1) Eustatic level (sea-surface) change
2) Isostatic or tectonic change
 Glacial isostasy
 Uplift beneath the melted ice
 Subsidence on the rim of melted ice
3) Local coastal processes
SEA-LEVEL CHANGE: Processes and time-scales
1) Sea-surface level change (eustatic level)
2) Isostatic or tectonic change
 Glacial isostasy
 Uplift beneath the melted ice
 Subsidence on the rim of melted ice
 Hydro isostasy
 Melted water creates additional load on the ocean floor- subsidence
3) Local coastal processes
SEA-LEVEL CHANGE: Processes and time-scales
1) Sea-surface level change (eustatic level)
2) Isostatic or tectonic change
3) Local coastal processes
 Local isostatic adjustment
 Tectonic compression
 Elastic rebound
 Faulting, folding, tilting
 Earthquakes
 Tidal regime change
 …etc.
OUTLINE
1. Motivation
2. Sea-level change: processes and time-scales
3. Methodology for defining relative sea-level (RSL)
4. Holocene RSL around the globe
• Barbados, Tahiti, Papua New Guinea
• Scotland
• Caribbean and South America
5. Conclusions
Methodology for defining RSL curves
Sea-level indicators
1) Corals
• Acropora palmata is widely used, lives within 5 m of the water surface
• Microatolls- indicative range ~3cm
2) Geomorphologic features (wide indicative range)
• Paleoshoreline notches
• Paleoreef flats
• Beach deposits
• Terraces
3) Fixed biologic indicators
• Rock clinging oyster beds
• Fossil tubework encrustations
4) Fossils and microfossils
5) Sedimentary facies
Mostly based on Woodroffe (2005)
Methodology for defining RSL curves
• Use a variety of environmental indicators to define RSL
• Terminology:
• Indicative meaning
• Reference water level (RWL)
• Indicative range (IR)
Woodroffe (2005)
OUTLINE
1. Motivation
2. Sea-level change: processes and time-scales
3. Methodology for defining relative sea-level (RSL)
4. Holocene RSL around the globe
• Barbados, Tahiti, Papua New Guinea
• Scotland
• Caribbean and South America
5. Conclusions
HOLOCENE RSL around the globe
Tahiti
Barbados
Papua
New Guinea
Tahiti: Barrier reef drilling
• 2 reef cores (700 m apart): P6, P7
• Sequence of reef carbonates
• overlie basalts at 114 m depth
• 2 units, unconformity at ~87 m depth
• 230Th/234U dating: error 30-60 years
• Species assemblage: corals,
encrusting algae, foraminifers,
gastropods
• Far from plate boundaries
Bard et al. (1996)
Tahiti RSL curve
• Continuous increase in RSL
• Small change @ 11,500-11,000 yr. BP
• Hiatus @ 13,700 years
Major sea-level jump
Bard et al. (1996)
Barbados offshore
drilling program
• 16 cores
• Near-continuous sequence
• 7,800-17,100 yr BP
• Radiocarbon dating (error <130 yr)
• Active subduction zone, located on
accretionary prism between two
plates
• assumed continuous uplift
Fairbanks (1989)
Barbados
RSL curve
• Best estimate for Holocene sea-level change ~120 m
• 13,500: MWP-1A– meltwater pulse 1Amajor SL rise
• 11,000: MWP-1B- metlwater pulse 1B another SL rise
• 11,500-11,000: Younger Dryas thermohaline circulation stopped as a
result of major fresh water input in North Atlantic
 New Guinea curve very similar to Barbados curve, supports MWP 1A
and 1B events
Bard et al. (1996)
Barbados, Tahiti, Papua New Guinea: Eustasy
• Rise in sea-level from 18,000-3,000 yr
• Contemporaneous meltwater pulses and Younger Dryas event
• Although tectonic setting very different, RSL curves very similar
 This largely defines eustatic signal
Bard et al. (1996)
OUTLINE
1. Motivation
2. Sea-level change: processes and time-scales
3. Methodology for defining relative sea-level (RSL)
4. Holocene RSL around the globe
• Barbados, Tahiti, Papua New Guinea
• Scotland
• Caribbean and South America
5. Conclusions
HOLOCENE RSL around the globe: Scotland
Shennan et al. (2000)
HOLOCENE RSL around the globe: Scotland
Shennan et al. (2000)
Peltier et al. (2002)
HOLOCENE RLS around the globe: Scotland
Shennan et al. (2000)
silt and clay
RSL determined using:
• Cores
• Lithostratigraphy
• Biostratigraphy
• Polen
• Diatoms
• Chronostratigraphy
organic limus
HOLOCENE RSL around the globe: Scotland
Shennan et al. (1999, 2000)
org.dep.
sand
HOLOCENE RSL around the globe: Scotland
Sea-level fall
Age (ka)
Shennan et al. (2000)
Scotland: Glacial isostasy
Last glacial maximum
1) Glacial period
SCOTLAND
ICE
2) Ice melts
3) Rebound
Uplift
Subsidence
Subsidence
OUTLINE
1. Motivation
2. Sea-level change: processes and time-scales
3. Methodology for defining relative sea-level (RSL)
4. Holocene RSL around the globe
• Barbados, Tahiti, Papua New Guinea
• Scotland
• Caribbean and South America
5. Conclusions
HOLOCENE RLS around the globe
Caribbean and South America
Milne et al. (2005)
Caribbean and South America
Age (ka)
Jamaica
Suriname
•24 samples
•Mangrove peats,
others?
•55 samples
•Sedge, mangrove,
swamp forest
•4 samples
•Corals, mangrove
sediments, massive
carbonates
?
Sea-level (m)
Recife
Curacao
•8 samples
•Vermitid
Milne et al. (2005)
Caribbean and South America
Rio de Janeiro
Strait of Magellan
•28 samples
•Mangrove, vermitid
•8 samples
•Peat, shells
Recife
Beagle Channel
•27 samples
•Vermitids, shells, wood
Sea-level (m)
Santa Catarina
•27 samples
•Shells in raised beaches
Age (ka)
Milne et al. (2005)
Caribbean and South America
• Very different behavior RSL records for
a coast of a single continent
• Caribbean coast tectonically active
• Atlantic coast- passive margin
 Can not be attributed completely to
eustatic signal
Eustatic signal
Model
Milne et al. (2005)
Age (ka)
Jamaica: geoidal isostasy
Jamaica
10
8
Time (ka)
6
4
2
0
SL (m)
Sea-level (m)
Geoidal isostasy
Non-eustatic
Eustatic signal
Interlacial geoid
Glacial geoid
Data
Milne et al. (2005)
Jamaica: Non-eustatic
Geoidal isostasy
Non-eustatic
Hydro isostasy
Eustatic signal
Data
Non-eustatic
Glacial isostasy
Milne et al. (2005)
Jamaica: Glacial isostasy
Geoidal isostasy
1) Glacial period
ICE
Hydro isostasy
Non-eustatic:
spatially varying
Eustatic signal
2) Ice melts
Data
Non-eustatic
3) Rebound
Glacial isostasy
Uplift
Subsidence
Subsidence
Milne et al. (2005)
Jamaica: Hydro isostasy
Geoidal isostasy
Non-eustatic:
Glaciationspatially varying
Hydro isostasy
Eustatic signal
M1
Data
Non-eustatic
Deglaciation
M2 > M1
Glacial isostasy
Sea-floor subsidence
Milne et al. (2005)
OUTLINE
1. Motivation
2. Sea-level change: processes and time-scales
3. Methodology for defining relative sea-level (RSL)
4. Holocene RSL around the globe
• Barbados, Tahiti, Papua New Guinea
• Scotland
• Caribbean and South America
5. Conclusions
CONCLUSIONS
• Large number of factors influence RSL
• Different stratigraphic and geomorphologic data used
• Areas far from ice-sheets (Barbados, Tahiti, Papua New Guinea)
 Constrain eustatic sea-level change
 Climatologic, oceanographic studies
• Glaciated regions (Scotland)
 Affected by postglacial rebound
 Constrain rheological structure of the Earth
• Intermediate regions
 Complex interplay of ice-, ocean- and tectonic- related processes
 Geodynamic implications
REFERENCES
1.
Bard, E., Hamelin, B., Arnold, M., Montaggioni, E, Cabioch, G., Faure, G., and F. Rougerie, 1996,
Deglacial sea-level record from Tahiti corals and the timing of global meltwater discharge, Nature,
382, 241-244.
2. Chappell, J. and H.Polach, 1991, Post-glacial sea-level rise from a coral record at Huon Peninsula,
Papua New Guinea, Nature, 349, 147-149.
3. Clark, J.A., Farrell, W.E., and W.R. Peltier, 1978, Global changes in postglacial sea level: A numerical
calculation, Quaternary research, 9, 265-187.
4. R.G. Fairbanks, 1989, A 17,000-year glacio-eustatic sea level record: influence of glacial melting on
the Younger Dryas event and deep-ocean circulation, Nature, 342, 637-642.
5. Milne, G.A., Long, A.J., and S.E. Bassett, 2005, Modeling Holocene relative sea-level observations
from the Caribbean and South America, Quaternary Science Reviews, 24, 1183-1202.
6. Peltier, W.R., Shennan, I., Drummond, R. and B. Horton, 2002, On the postglacial isostatic adjustment of
the British Isles and the shallow viscoelastic structure of the Earth, Geophysical Journal International, 148,
443-475.
7. Scholl, D.W., Craighead, F.C., and M. Stuiver, 1969, Florida submergence curves revised: Its relations to
coastal sedimentations, Science, 163, 562-564.
8. Shennan, I., Tooley, M., Green, F., Innes, J., Kennington, K., Lloyd, J. and M. Rutherford, 1999, Sea level,
climate change and coastal evolution in Morar, northwest Scotland, Geologie en Mijnbouw, 77, 247-262.
9. Shennan, I., Lambeck. K., Horton, B., Innes, J., Lloyd, J., McArthur, j., Purcell, T., and M. Rutherford,
2000, Late Devonsian and Holocene records of relative sea-level changes in northwest Scotland and
their implications for glacio-hydro-isostatic modeling, Quaternary Science Reviews, 19, 1103-1135.
10. Shennan, I., Peltier, W.R., Drummond, R. and B. Horton, 2002, Global to local scale parameters
determining relative sea-level changes and the post-glacial isostatic adjustment of Great Britain, Quaternary
Science Reviews, 21, 397-408.
11. Toscano, M.A. and J. Lundberg, 1998, Early Holocene sea-level record from submerged fossil reefs on the
southeast Florida margin, Geology, v.26, n0.2, 255-258.
12. Woodroffe, S.A. and B.P. Horton, 2005, Holocene sea-level changes in the Indo-Pacific, Journal of
Asian Earth Sciences, 25, 29-43.
Non-eustatic signal
TOTAL
Glacial isostasy
Hydro isostasy
Milne et al. (2005)
HOLOCENE RSL around the globe
Collapsing forebulge submergence
1) Glacial period
ICE
2) Ice melts
Age (ka)
Jamaica
3) Rebound
SL (m)
Uplift
Subsidence
Subsidence
Clark et al. (1978)