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HE SEDIMENTATION P ERU CONT INENTAL MARGIN IN ; ; NTINENTAL NG - - PowerPoint PPT Presentation

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IAEA CN-186 28 Mar 1 Apr 2011 Monaco Workshop 1: Isotopes in Marine Climate Studies R EGIONA ONAL CONT LS ON ON H OLOCE NE NTRO ROLS CENE MENTATION PATTERNS TERNS ALONG NG THE HE SEDIMENTATION P ERU CONT INENTAL MARGIN IN ; ; NTINENTAL NG

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REGIONA

ONAL CONT NTRO ROLS LS ON ON HOLOCE CENE NE SEDIMENTATION MENTATION PATTERNS TERNS ALONG NG THE HE

PERU CONT

NTINENTAL INENTAL MARGIN IN;

;

LONG NG TERM RM IMPLIC MPLICATI ATIONS ONS FOR EL NIÑO ÑO-SOUTHERN OUTHERN

OSCILLA

ILLATI TION ON

Greg g SKIL ILBECK BECK, , Dim imitr itri GUTI GUTIERR ERREZ, EZ, Bert REIN IN, , Abdel el SIF IFEDDINE, EDDINE, Renato to SALVATTECI, VATTECI, David d FINK NK, , Ellen en DRUFF FFEL EL, , Joan-Al Alber bert t SANCHEZ CHEZ-CAB CABEZA, EZA, Rob DUNBA NBAR

IAEA CN-186 28 Mar – 1 Apr 2011 Monaco

Workshop 1: Isotopes in Marine Climate Studies

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ENSO SO & Peru u Margi gin n Sedim diments nts

El Niño-Southern Oscillation (ENSO)

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Outline

Wh Where ere is is our

  • ur un

understandi erstanding ng no now? “New” data

  • Radiocarbon re-calibration
  • Pattern of sediment accumulation
  • Geochemical evidence

Oc Oceanogra eanographic phic im impli licatio cations ns

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Is this (interannual) ENSO?

The GUIDELINE Modern (instrumental) ENSO recurrence 2 – 7 years

  • ver ~130 years with modal frequency ~5+ yr

The EVIDENCE Geoch chemis emistry try (multiproxy, consistent, but incomplete

time series)

Image age Anal alys ysis is (resolution 0.1 mm per pixel; interannual

aliasing precluded, pixels per year?)

Layer er Counti nting ng (subjective, independent of image analysis)

New - Chronology

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Palaeo – ENSO: Previous work

What is the problem?

ENSO reduced or absent between 15ka and 6ka

Sand ndweiss eiss et al. . 1996 1996a & b; between 5800 and 3200-2800 Cal yr BP, El Nino events less frequent that today, and for several millennia prior to 5800 yr El Nino “absent or very different from today” (archaeological, molluscs) (8oS – 18oS) (Geology, Nature) Koutavas utavas et al., ., 2002 2002; ; 30,000 yr low-resolution magnesium-calcium ratio in foraminifera near Galapagos Is compared with west Pacific alkenone SST record show “mid-Holocene cooling” suggestive of La Nina conditions; late mid and early Holocene, and 14-15 ka (Bølling) similar to today (Science) Moy y et al., ., 2002 2002; ; Continuous 12,000 yr record from Lake Pallcacocha; not quite ENSO interannual resolution, but variance in red colour intensity record suggests low variance in the Early Holocene; either ENSO starts after 7,000 yr BP, or is weak in the Early Holocene (2o-3oS) (Nature) Gagan an et al. 2004 2004; ; Onset of ENSO periodicities at ~5000 yrBP, with a sudden increase in ENSO magnitude at ~ 3000 yrBP and maximum ~2300- 1700 yr BP; precipitation response to El Nino temp anomalies “subdued” in mid Holocene; western-central Pacific; attributed to mean southward shift in the ITCZ [Quaternary International]

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Eastern Pacific Holocene Record

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Tropical Pacific SST Gradient

From Koutavas et al. 2002 (their Fig. 3)

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from Rein et al. 2005 (their Fig. 11)

Rein et al. 2005; SST ~ 2oC warmer than today between 10,300 and 8,900 yr BP; El Nino declining over last 800 yrs; Alkenone SST data; primary productivity index and terrestrial proxy for ENSO flooding since LGM; [Paleoceanography]

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Summary

♦ Modern ENSO pattern continuous since post mid Holocene ♦ Tropical Pacific SST gradient greater in middle Holocene than currently ♦ Records not consistent for Early Holocene or LGIT ♦ Gaps? What happens to the currents and sediment in El Nino heartland during these periods?

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“New” data

Recalibrated and regionally extensive radiocarbon data Regionally consistent pattern of sediment accumulation High-resolution geochemical and image data

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Location & Material

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Regional Marine Reservoir Correction

Ortleib leib et al., ., 2010 10: : [Quaternary Research]

On basis of co-located terrestrial (charcoal) and marine (shells) radiocarbon along Chilean coast determined extensive variability in regional marine reservoir effect DR 2s range between 1000 – 500 yr but three-fold subdivision of Holocene: » 511 511± 278 278 yr (10,500-6,800 yr BP) » 226 226± 98 98 yr (5,200-1,000 yr BP) » 250 250-350 350 yr (<1000 yr BP) Inferred significant changes in ocean currents particularly with old carbon source (i.e. upwelling) reduced after 5000 yrs (i.e. long-term El Nino-like conditions increasing after 5500 – 5300 yr BP)

We have e recalibrated calibrated all prev eviou iously ly published lished radiocarbon diocarbon ages es using ng DR :

» 511 511± 278 278 yr (for

  • r > 5000

0 yr) » 279 53 (for r 0-5000 5000 yr) and the Marine rine09.14 09.14C C Reimer imer et al. . (2009 09) ) Radioca iocarb rbon

  • n 51

51

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Holocene Age-Depth

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Regional Pattern of Sedimentation

100- 150 cm/ka

~2250 yrBP

20-50 cm/ka 4-10 cm/ka 90-120 cm/ka

~4400 yrBP ~8150 yrBP ~15000 yrBP

(~250 cm/ka) (~10-50 cm/ka)

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Changes in Sedimentation Rate?

The Record:

  • Sediment bypass
  • Deposition and Erosion
  • Changes to volume of sediment delivery

Mechanisms

  • Ocean current velocity/direction (strong

upwelling in middle Holocene)

  • Productivity/Nutrient load
  • Terrestrial input
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XRF Scanning Data

Avaatech XRF Core Scanner 106 06KL KL (Marum Bremen); 122 229E, E, 122 227A (College Station) Nineteen elements @ 2 mm interval

  • Al Si P S Cl K Ca Ti Mn Fe Rh
  • Cu Zn Br Rb Sr Zr Mo Pb
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1227A 1229E

Si:Al, Mo:Al, Ca Trends

106KL

~2250 yrBP ~4400 yrBP ~8150 yrBP ~15000 yrBP

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Statistics

106KL late Holocene 1229E late Holocene silicon calcium Terrestrial group

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Statistics (cont)

106KL early Holocene 1229E early Holocene silicon calcium Terrestrial group

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Stratigraphy

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The Cores – Late Holocene

106KL 1229E top top

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The Cores – Middle Holocene

106KL 1229E top top

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The Cores – Early Holocene

106KL 1229E top top

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Summary

Sedimentary layers of at least four types Middle Holocene time of disruption – evidence of both bioturbation (slow sedimentation & oxygenated bottom waters?) and slumping (increased current velocity) Early and Late Holocene similar in terms of deposition and preservation of laminae LGIT – yet to be resolved; geochemically different, extensive slumping, high sedimentation rates, interannual laminations

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END

Acknowledgements

♦ K41009: Nuclear and isotopic studies of the El Niño phenomenon in the ocean ♦ AINSE SE (grant ant number mbers 02 02/169 169, , 04 04/139 139, , 05 05/151 151)

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Grain Size

Grain size

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Stokes Settling

2 yr 3 m 18 days 20 m

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Oxygen Minimum Zone Red: Extreme El Niño Yellow: Normal

  • J. Helly, Scripps Supercomputer Center

Pacific Ocean Peru Trench Andes Galapagos Islands

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Geochemical Results

El Nino “Normal” If temperature ~ 1OC warmer If salinity ~ 0.5 PPT fresher Decreased calcite production Decreased TOC Assume pale = 100% marine with d13C -21.5‰ and typical C3 with - 27‰, then shift of -0.46‰ ~ 8% terrestrial mixing

SST Precipitation Ocean “productivity” Terrestrial vegetation

Darker layers are:

  • Warmer
  • Wetter
  • Reduced

“productivity”

New - Geochemistry

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= Dark bands = Light bands Stress = 0.15 p-F = 3.21, P < 0.01

Results of non-parametric multivariate comparison of dark vs light bands. Data are Normalised and Euclidean distance coefficient was used. nMDS is used to graphically represent the comparison and NP-MANOVA was used to test the hypothesis.

New - Geochemistry

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Modern ENSO Time Series

normalised power

Trenberth & Hurrell (1993) Zhang et al. (1997) Urban et al. (2000)

New – Times Series

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Time Series

Red colour intensity of interannual ENSO (band pass filter to extract 2-7.5 yr variance – ) Amplitude modulation of interannual ENSO – Layer trends (events per 100 yr)

aqua curve green curve Three Sets of Spectral Analyses:

(Evolving spectrograms of normally-distributed data using Blackman-Tukey FFT with Hanning window )

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Late Holocene Time Series 1229E

ENSO band variance amplitude modulation LIA Medieval Warm Dark Ages

100-200 yr

normalised power

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Frequency ~ 220 yr (Suess?) Inverse correlation between events per 100 years and thickness per 10 cms (i.e. if more layers per time, they are thinner ~constant sedimentation rate) ~ inverse correlation between thickness per 10 cm and % dark per couplet (i.e. where there are more events per 100 yr, ENSO (dark) part of the couplet is dominant) Recent past compaction articfact?

Industrial LIA Medieval Warm Middle Ages Cold 422 layers

New – Layer Trends

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Early Deglaciation Time Series 1227B

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Evolving spectrum ENSO variance Evolving spectrum amplitude oscillation

Deglaciation Time Series 1227B

Evolving spectrum ENSO variance ~6.4 yr ~11.0 yr ~5.7 yr

Allerod (warm) OD (cold) (warm) H1 (cold)

~54 yr ~30 yr 200- 70 yr