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 Age (million years BP) Sea-level height (m)  My research interest  Modeling long-term geodynamic influence on sea-level change  How does long-term sea-level change?

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 Barbados Tahiti 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 230 Th/ 234 U dating: error years Species assemblage: corals, encrusting algae, foraminifers, gastropods Far from plate boundaries Bard et al. (1996)

Tahiti RSL curve Bard et al. (1996) Continuous increase in RSL Small 11,500-11,000 yr. BP 13,700 years  Major sea-level jump

Barbados offshore drilling program Fairbanks (1989) 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

Barbados RSL curve Bard et al. (1996) 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

Barbados, Tahiti, Papua New Guinea: Eustasy Bard et al. (1996) 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

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)

HOLOCENE RSL around the globe: Scotland Shennan et al. (1999, 2000) organic limus silt and clay org.dep. sand RSL determined using: Cores Lithostratigraphy Biostratigraphy Polen Diatoms Chronostratigraphy

HOLOCENE RSL around the globe: Scotland Shennan et al. (2000) Sea-level fall Age (ka)

Scotland: Glacial isostasy ICE 1) Glacial period 2) Ice melts Uplift Subsidence 3) Rebound Last glacial maximum SCOTLAND

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 Milne et al. (2005) Age (ka) Jamaica Curacao Sea-level (m) Suriname Recife 55 samples Sedge, mangrove, swamp forest 4 samples Corals, mangrove sediments, massive carbonates 8 samples Vermitid ? 24 samples Mangrove peats, others?

Caribbean and South America Milne et al. (2005) Strait of Magellan Recife Beagle Channel Age (ka) Sea-level (m) Rio de Janeiro Santa Catarina 8 samples Peat, shells 27 samples Shells in raised beaches 28 samples Mangrove, vermitid 27 samples Vermitids, shells, wood

Caribbean and South America Milne et al. (2005) Very different behavior RSL records for a coast of a single continent Caribbean coast tectonically active Atlantic coast- passive margin Eustatic signal Model  Can not be attributed completely to eustatic signal

Data Eustatic signal Geoidal isostasy Non-eustatic Jamaica: geoidal isostasy Milne et al. (2005) Jamaica SL (m) Age (ka) Glacial geoid Interlacial geoid Time (ka) Sea-level (m)

Data Eustatic signal Geoidal isostasy Non-eustatic Jamaica: Non-eustatic Glacial isostasy Hydro isostasy Milne et al. (2005) Non-eustatic

Data Eustatic signal Geoidal isostasy Non-eustatic: spatially varying Jamaica: Glacial isostasy Glacial isostasy Hydro isostasy Milne et al. (2005) Non-eustatic ICE 1) Glacial period 2) Ice melts Uplift Subsidence 3) Rebound

Data Eustatic signal Geoidal isostasy Non-eustatic: spatially varying Jamaica: Hydro isostasy Glacial isostasy Hydro isostasy Milne et al. (2005) Non-eustatic Glaciation Deglaciation M1M1 M 2 > M 1 Sea-floor 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

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, Chappell, J. and H.Polach, 1991, Post-glacial sea-level rise from a coral record at Huon Peninsula, Papua New Guinea, Nature, 349, Clark, J.A., Farrell, W.E., and W.R. Peltier, 1978, Global changes in postglacial sea level: A numerical calculation, Quaternary research, 9, 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, 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, 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, Scholl, D.W., Craighead, F.C., and M. Stuiver, 1969, Florida submergence curves revised: Its relations to coastal sedimentations, Science, 163, 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, 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, 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, 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, Woodroffe, S.A. and B.P. Horton, 2005, Holocene sea-level changes in the Indo-Pacific, Journal of Asian Earth Sciences, 25,

Non-eustatic signal Milne et al. (2005) TOTAL Glacial isostasy Hydro isostasy

HOLOCENE RSL around the globe Clark et al. (1978)

HOLOCENE RSL around the globe: NOT SO SIMPLE Scotland Jamaica SL (m) Age (ka) Beagle Channel SL (m) Age (ka) Suriname SL (m) Age (ka)

HOLOCENE RSL around the globe Ocean floor subsidence -Additional weight of water  ocean floor subsides Clark et al. (1978)

HOLOCENE RSL around the globe

Collapsing forebulge submergence ICE 1) Glacial period 2) Ice melts Uplift Subsidence 3) Rebound Jamaica SL (m) Age (ka) Clark et al. (1978)