Centennial to decadal climate variability in the Adriatic Sea during Sapropel S1
Marie-Louise S. Goudeau*, Gert-Jan Reichart, Tom Jilbert, Shauna Ní Fhlaithearta, and Gert J. De Lange
* M.S.Goudeau@uu.nl
Introduction
Ion ian Se a Ad ria tic
S ea
Thy rren ian S ea
12°E 14°E 16°E 18°E 20°E
40°N 42°N 44°N 46°N
Po R.
Delta
Italy
WAC WAC
ISW
Mediterranean Sea
Otra ntoS
trait River/Canyon
Mountains
Ionian Surface Water Core tops
WAC
IS W
Gulf
ofTaranto
Ape nnine
mou ntains
ISW Western Adriatic
Current
NA dDW
SAdDW
Apulia
Calabria
Cape SML ADW
Adriatic Deep Water
ADW
GeoB107-39 JULY
ITCZ
Cold/Dry Bora
38°N L
H NAO+
Westerlies Less winter-rain
Dry /warm summers
a b
Sample Ca Ti S Fe+S
b
b
Ca=yellow, Ti= purple, S= green, Fe=red,Fe + S is purple/pink
In the Eastern Mediterranean, enhanced organic matter fluxes to the seafloor and anoxia encourage the formation of organic rich sediment units, known as sapropels.
Recent studies have shown that conditions during the sapropel for- mation are less stable than previously assumed, e.g the latest Sap- ropel S1 is interrupted on both millennial and centennial time
scales.
Here we present a high resolution geochemical study of a sub-
milimetric scale laminated sapropel S1from the southern Adriatic.
The duration of the observed laminar couplets appear to be as short as a decade. We discuss the processes responsible for the compositional contrasts in the laminae, and the climatic drivers of variability in these processes.
Core site & Methods
• Homogenous matrix
• Laminae are enriched in Fe and S→ Pyrite
(FeS )
• Pyrite in laminae are framboidal
2
Core site
Subsampling at 5 mm resolution for ICP-OES/ Bulk isotopes
Trays (2x ~20 cm) taken for:
• resin embedding of sediments under anoxic conditions
• resin block are analysed : 1. µXRF
2. LA-ICP-MS
3. Color analysis using a method exclud- ing cracks (Zeeden et al., submitted)
Methods
Mo/Al (cps/cps)
A* (red scale) Fe+S (uXRF)image Grey scale L*
ANOXIA
0
1
2
3
0.5
1.5
2.5
3.5
200 180 160 140 120
200 240 280 320 0 2E-005 4E-005
LA-icp-ms track
Laminae are:
• Dark
• High in Pyrite
• Enriched in Mo
→Sulfidic conditions at dediment interface during laminae formation
Greyscale pattern:
similar to pattern of bulk Mo/Al & Ba/Al =>
=> Anox.conditions &
high Export Productivity Greyscale lamination:
decada(4-16 yr) to centennial (~60-100 yr) periodicity
no laminations at:
low Mo/Al & Ba/Al
14 C dating point
7600 8000 8400 8800
240 320 400
-1.5 -1.6 -1.7
14 15 16
2 4 6
380 400 420 440
Period
7400 7600 7800 8000 8200 8400 8600 8800 2
4 8 16 32 64 128 256
512 1/64
1/16 1/4 1 4 16 64
Age (yr BP)) Age (yr BP)
L* (greyscale) Ba/Al (ppm/%)
Mo/Al (ppm,/%) δ
18O B ul k
L* (greyscale) Period
No laminations No laminations
U k ’3 7 Te m pe ra tu re (° C ) (S an gi or gi e t a l., 20 03)
References:
Fleitmann, D., et al.(2003), Holocene Forcing of the Indian Monsoon Recorded in a Stalagmite from southern Oman, Science, 300, 1737–1739
Mayewski, P. A., L. D. Meeker, M. S. Twickler, S. I. Whitlow, Q. Yang, W. B. Lyons, and M. Prentice (1997), Major features and forcing
of high-latitude northern hemisphere atmospheric circulation using a 110,000-year-long glaciochemical series, J.
Geophys. Res., 102, 26,345–26,366
Sangiorgi, F., et al., ( 2003). Holocene seasonal sea-surface temperature variations in the southern Adriatic Sea inferred from a multiproxy approach. J. of Quaternary Science, 18(8), pp. 723-732.
Van der Linden, R.A.M. and the SIDC team, online catalogue of the sunspot index, http://sidc.oma.be/html/sunspot.html.
Zeeden, C, et al.. (submitted). An application to correct for cracks in core images (submitted to Marine Geology)
Sample and Fe+S content
Introduction
Image analysis and LA-ICP-MS
µXRF & SEM Greyscale vs. Bulk Geochemistry
0.05 0 0.1 0.15 0.2 0.25 0.3 0.35 0.4
500 1000 1500
Frequency (1/yr) Evolutionary Power Spectrum
Time (yr)
0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4
200 400 600 800 1000 1200 1400
Frequency (1/kyr) Evolutionary Power Spectrum
Time (kyr)
Age ( AD ) 1700
2009
Time (yr) L* (this study) Sunspot
Frequency (1/yr)
20 10 5
Period (yr)
6.67
7600 8000 8400 8800 240
320 400 1
-1.6 -2 -2.4
-0.8 -0.4 0 0.4
Total solar irradiance (TSI)
L* δ
18O Q un f C av e (F le itm an n et a l. 20 03 )
increased Siberian High
ITCZ southwards
Lo g K + in G IS P2 (M ay ew sk i e t a l. 19 97 ) no laminations no laminations
No laminations: High siberian High (cold bora winds) + ITCZ southwards:
both can cause ventilation
When laminations occur: high correlation with TSI Forcing Mechanisms?
Conclusions:
• Dark lamina during S1 : more anoxic conditions and increased export productivity
• Variability occurs on a decadal time scale
• Variability is related to total solar irradiance
<-Sapropel S1->
No laminationsNo laminations No laminations
