The Palaeoenvironmental Significance of Foraminifera

Report
Professor Brent Wilson FGS
Petroleum Geoscience Programme, Department of Chemical Engineering,
The University of the West Indies, St. Augustine
A few definitions
 Ecostratigraphy: The study of the occurrence and
development of fossil communities throughout geologic time
 Middle to Late Quaternary: the last ~0.78 Ma – latter part of
the Pleistocene and the Holocene
 Inner Neritic: 0 – 20 m water depth
 Middle Bathyal: 500 – 1000 m water depth
Impetus behind this study – a failed research question
 Streeter (1973), Gaby and Sen Gupta (1985): marked glacial-




interglacial contrasts in benthonic foraminifera at bathyal and
abyssal depths
Signal varies in strength aerially (Streeter and Lavery, 1982)
Some papers report muted contrasts (Sen Gupta et al., 1991;
Wilson, 2008)
Wilson and Costelloe (2011) - classification of abundance
biozone boundaries
Do AB boundaries coincide with glacial-interglacial
boundaries?
An Advance Organiser (as education people call them)
This talk will demonstrate:
 Increase in organic matter flux at ODP Site 1006 (Santaren
Channel)
 Flux of shallow water foraminifera independent of sea level
change
 Bathyal and neritic regime shifts across Marine Isotope Stages
8-9
 Percent carrying capacity changes of common bathyal species
across MIS 8-9
What are Forams?
For those who weren’t taught these things at school
•Single celled bugs <1 mm
•Planktonic (float near sea surface)
•Benthonic (live on seafloor)
•Shelled
•Narrow ecological niches
•Abundant in marine
environments
•Beautiful
Bolivina jiattongae Wilson, 2006
•Some neritic, coral reef forams
•Specimens modern, from St. John,
USVI
•C, G, H and I symbiotic with algae –
need light
•Restricted to shallow water
Wilson, B. (2011). The impact of hurricanes on epiphytal
Foraminifera on rhizomes of the seagrass Thalassia testudinum,
Nevis, north-eastern Caribbean Sea. In Pirog, R. S. (ed.),
Seagrass: Ecology, Uses and Threats, Nova Science Publishers,
Hauppauge, New York, USA, 117-138, Figure 1.
•Around St. Kitts, Asterigerina carinata
dominates between 6-17 m.
•Around Jamaica, Sigmavirgulina tortuosa
common on seagrasses at <3 m
•Around Nevis, Triloculina bermudezi
common in polluted bays at <3 m
•This information will be important later
on 
Maps from Wilson, B., Orchard, K. and Phillip, J. (2012). SHE Analysis for Biozone Identification among Foraminiferal Sediment Assemblages
on Reefs and in Associated Sediment around St. Kitts, Eastern Caribbean Sea, and its Environmental Significance. Marine
Micropaleontology, 82-83, 38-45.
The carbonate Bahama Platform
Light blue areas, shoal water
Dark blue areas, bathyal to abyssal water
Study area at left
What is highstand shedding?
When a carbonate
platform sheds
sediment into adjacent
basin during
highstands of sea level
Frequent during
Quaternary
interglacials
What is a drift deposit?
•Wedge of sediment along
continental margin reworked by
margin-parallel currents
•Shallow drifts – surface currents
•Deep drifts – subsurface counter
currents
•May rework turbidites
•Coarse-grained for depth of
occurrence
•Good hydrocarbon reservoirs
Anselmetti F S et al. Geological Society of America Bulletin
2000;112:829-844
Shallow drift between Bahamas and
Florida
Santaren Current joins with Florida
Current to become Gulf Stream
Source of material in drift unclear –
Bahamas, Cuba or both:
•clays from continental crust
(Cuba)
•much aragonite (Bahamas)
Santaren Drift on Seismic Section – Miocene to
Recent (25 million years)
Changes in lithology
Subunit IA (0-7.28 mbsf): light grey and
white to pale yellow nannofossil ooze
Subunit IB (>7.28 mbsf): light grey
nannofossil ooze with interbedded clays
and silty clays
Is there a change in fauna at the change
in lithology?
A typical subunit IB cycle: from Eberli, G. P., Swart, P. K. & Malone, M.
J. 1997a. Site 1006. In: Proceedings of the Ocean Drilling Program,
Initial Reports (eds Eberli, G. P., Swart, P. K. & Malone, M. J.), pp. 233 287.
Onwards to the (reefal) forams!
Above: Marine Oxygen Isotope
Stages from aragonite flux
Below: Neritic foraminiferal flux
(as percentage) in Cores 1-3,
ODP Hole 1006A
Odd numbered stages are
interglacials – every ~100 ka
High flux in MIS 9, but clear
oxygen isotope signal – not
slumping en masse to site?
37% of foraminifera in deep-water ODP 1006A derived from shoal-water
<20 m deep
26 ka
Shallow water foram diversity in ODP Hole 1006A
•Diversity measured using information function H = -Σpi·lnpi, where
pi = proportional abundance of ith species
•Note change in mean diversity at ~10.5 m
•Change not coincident with change in lithology
•Change part way through MIS 9
•Change in organic carbon flux?
Eigenvalue
% variance
Angulogerina occidentalis
Articulina pacifica
Asterigerina carinata
Brizalina paula
Brizalina subexcavata
Caribeanella polystoma
Cibicides advena
Elphidium translucens
Miliolinella circularis
Axis 1
5.64
28.21
0.60
–0.8651
–0.512
0.58
0.42
–0.6941
–0.1555
–0.01369
–0.6195
Axis 2
Axis 3
2.98
1.80
14.93
8.98
–0.3127
0.23
–0.2085
0.09
–0.4776
0.32
0.12
–0.4187
–0.1827
0.19
–0.4953
0.12
0.53
0.49
–0.5411
0.17
–0.2757 –0.2056
Axis 4
1.61
8.03
–0.1671
–0.09609
–0.07396
–0.04684
–0.1715
–0.1611
0.22
0.52
–0.02673
Axis 5
1.39
6.93
0.15
–0.08816
–0.2359
–0.3565
0.68
–0.2789
-0.08
0.24
–0.06301
Axis 6
1.11
5.57
–0.02902
0.04
–0.3825
–0.1906
0.17
0.05
–0.02026
–0.03379
0.54
Planulina foveolata
Quinqueloculina auberina
Quinqueloculina lamarckiana
Quinqueloculina poeyana
–0.4204
–0.3422
–0.5023
–0.5896
0.60
–0.2373
–0.2015
–0.1575
Rosalina bahamaensis
Rosalina globularis
Sagrina pulchella
Sagrina pulchella primitiva
Sigmavirgulina tortuosa
Siphonina pulchra
Triloculina bermudezi
–0.7992
0.12
0.53
0.30
0.78
–0.4708
–0.3655
–
–0.3493 0.008335 –0.1915 –0.1791
0.23
–0.3549 –0.2606
0.50
–0.3289 –0.2711
–0.5618
0.08
0.32
–0.2002
0.08
–0.5998
0.50
0.16
0.06
0.20
–0.2768
0.19
0.20
–0.1559
0.08
0.41
0.46
0.22
–0.09342
0.04
0.13
–0.4401
0.48
0.16
0.35
0.44
0.09
–0.3391
–0.1596
0.40
0.001885 –0.06834
–0.3837
0.22
–0.3613
0.32
0.36
–0.2679
0.20
0.38
–0.3039
Shoal-water recovery dominated by Asterigerina carinata (11%),
Caribeanella polystoma (12.1%) and Rosalina bahamaensis (22%)
Principal components analysis indicates these are not the best species to
use for ecostratigraphy of ODP 1006A
Distribution of selected shoal-water species
 A above = Articulina pacifica. Most
abundant in and above MIS 9
 B above = Sigmavirgulina tortuosa. Almost
absent in MIS 8-9
C above = Triloculina bermudezi.
Confirms increased organic flux from MIS
9 onwards
What happened to the bathyal assemblages?
Left: MIS vs. bathyal forams (= in situ
productivity) in top 3 cores, ODP Hole 1006A
Note dilute signal in MIS8-9
Right: Decrease in diversity across
MIS9 (indicative of enhanced
carbon flux in deeper water)
Downslope transport of bathyal foraminifera
Species
Globocassidulina subglobosa
Sigmoilopsis schlumbergeri
Siphonina bradyana
Sphaeroidina bulloides
Discanomalina semipunctata
Cibicidoides robertsonianus
Cibicidoides bradyi
Cassidulina crassa
Hoeglundina elegans
Cylindroclavulina bradyi
Uvigerina laevis
Globocassidulina punctata
Gyroidinoides neosoldanii
Cibicidoides umbonatus
Bigenerina irregularis
Melonis baarleeanus
Lenticulina rotulata
Cassidulina laevigata
Pearson's r
0.609
0.584
0.511
0.499
0.420
0.419
0.412
0.407
-0.402
-0.419
-0.422
-0.426
-0.434
-0.463
-0.529
-0.587
-0.616
-0.635
%Tb – percentage of total recovery as
‘bathyal’ foraminifera
Some species positively correlated with %Tb
(Globocassidulina subglobosa, Sigmoilopsis
schlumbergeri) – largely autochthonous,
39% of ‘bathyal’ assemblage
Some species negatively correlated with %Tb
– (Cassidulina laevigata, C. reflexa,
Lenticulina rotulata) – augmented by
allochthonous specimens , 19% of ‘bathyal’
assemblage
Bathyal forams as percentage of bathyal
foram community
Above: Cassidulina reflexa
abundant in MIS 9
Below: Globocassidulina
subglobosa rare in MIS 9, no
correlation with other MISs
Percentage carrying capacity Kp: A
prospective ecostratigraphic tool
Percentage point change in abundance of a
species Δpi between two samples given by
Δpi = pit+1 – pit
Rate of population change in percentage
points for each percent at time t (rt ) given
by
rt = Δpi /pit
Linear regression of rt against pit gives
rt = rm – s·pit
Intercept rm = rate of increase in rt where pit
approaches zero
Slope s = combined strength of
intraspecific, interspecific and abiotic
interactions for the species investigated
Changes in Kp across MIS9 for selected
bathyal benthonic foraminifera
•Kp can vary over time for a species
•Points of changes in Kp for a species mark
position of species’ regime shifts
•Regime shifts in different species not
always synchronous
Regime shift in G.
subglobosa in upper
section shown by
multiple attractors
A Warning!
“There is something fascinating
about science. One gets such
wholesale returns of conjecture
from out of a trifling investment
of fact.” (Mark Twain)
“We all know that we do not need
a complete data set to write an
acceptable (hi)story. A nice story
can equally well be written on
the basis of a very few data and a
fair amount of imagination.” (C. W
Drooger, 1993, Radial Foraminifera;
Morphometrics and Evolution, p. 19)
What caused the event in MIS8-9?
 Megatsunami
 McMurtry et al. (2007) – raised marine deposits on Bermuda
indicate mega-tsunami between MIS 9-11
 Would have stripped Bahama Platform of neritic sediment
 Hearty and Olson (2008) – tsunami deposit of MIS 11 highstand
age (399 ± 11 ka); sea levels +21 m?
 Waelbroek et al. (2002) – MIS 11 highstand only ~5 m above
present
 Slumping
 No slumping from Bahama Platform reached Santaren Drift
(Rendle-Buhring and Reijmer 2005; Mulder et al. 2012)
 Slumping from Cuba/Hispaniola, reworked by Santaren Current?
Cape
Hatteras
USA
34oN
32oN
Site 994
*
80oW
o
78 W
o
76 W
A. Displaced genera and species
Elphidium excavatum
0
1
2
3
4 0
0
B. In situ genera and species
Epistominella takayanagii
A
2 4 6 8 10 12 14 16 18
0
I
2
2
2
C
8
6
8
D
10
IV
10
E
12
12
V
14
20
25
Kp = 3.7%
i
ii
III
10
15
6
6
8
10
4
4
II
5
Kp = 11.9%
B
4
12
F
Uvigerina spp.
Globocassidulina obtusa
0
14
Kp = 9.3%
iii
Kp = 18.1%
iv
Kp = 12.9%
v
Kp = 5.6%
0
5
10
15
20
Conclusions 1 regarding ODP Hole 1006A
 Reefal source mostly <14 m (Asterigerina carinata)
 Neritic foraminiferal flux unrelated to glacial-interglacial cycles
 Change in diversity at ~10.5 m reflects increase in organic carbon flux –
reflected in abundance of Triloculina bermudezi
 Bathyal community – mixed autochthonous and allochthnous specimens
(Cassidulina reflexa, Globocassidulina subglobosa)
 Some percentage carrying capacities change across MIS 9
 Globocassidulina subglobosa shows complex pattern of change in
percentage carrying capacity above MIS 9
Conclusions 2
regarding ODP Hole 1006A
 So, two events in ODP 1006A.
 Flux of reefal foraminifera highest in MIS 8-9
 Change in flux of organic carbon across MIS 8-9
 Might not be related
 Possible tsunami in MIS 8-9? Doubtful
 Slumping from Cuba/Hispaniola?
References
 Buzas, M. A., Smith, R. K. & Beem, K. A. 1977. Ecology and systematics of foraminifera in
two Thalassia habitats, Jamaica, West Indies. Smithsonian Contributions to Paleobiology,
31: 1-139.
 Bernet, K. H., Eberli, G. P. & Gilli, A. 2000. Turbidite frequency and composition in the
distal part of the Bahamas transect. In: Proceedings of the Ocean Drilling Program,
Scientific Results (eds Swart, P. K., Eberli, G. P., Malone, M. J. & Sarg, J. F.).
 Eberli, G. P., Swart, P. K. & Malone, M. J. 1997a. Site 1006. In: Proceedings of the Ocean
Drilling Program, Initial Reports (eds Eberli, G. P., Swart, P. K. & Malone, M. J.), pp. 233 287.
 Peltier, W. R. & Fairbanks, R. G. 2006. Global glacial ice volume and Last Glacial
Maximum duration from an extended Barbados sea level record. Quaternary Science
Reviews, 25: 3322-3337.
 Phipps, M., Jorissen, F., Pusceddu, A., Bianchelli, S. & Stigter, H. C. d. 2012. Live benthic
foraminiferal faunas along a bathymetrical transect (282-4987 m) on the Portuguese
margin (NE Atlantic). Journal of Foraminiferal Research, 42: 66-81.
 Rose, P. R. & Lidz, B. 1977. Diagnostic Foraminiferal Assemblages of Shallow-water
Modern Environments: South Florida and the Bahamas. Sedimenta, 4: 1-55.
 Todd, R. & Low, D. 1971. Foraminifera from the Bahama Bank west of Andros Island. US
Geological Survey Professional Paper, 683-C: 1-22.
More references (yawn)
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Wilson, B. 2006. The Environmental Significance of Some Microscopic Organisms Around Nevis, West Indies. West
Indian Journal of Engineering, 28: 53-64.
Wilson, B. 2006. The environmental significance of Archaias angulatus (Miliolida, Foraminifera) in sediments around
Nevis, West Indies. Caribbean Journal of Science, 42: 20-23.
Wilson, B. 2006. Guilds among epiphytal foraminifera on fibrous substrates, Nevis, West Indies. Marine
Micropaleontology, 63: 1-18.
Wilson, B. 2008. Population structures among epiphytal foraminiferal communities, Nevis, West Indies. Journal of
Micropalaeontology, 27: 63-73.
Wilson, B. 2008. Late Quaternary benthonic foraminifera in a bathyal core from the Leeward Islands, Lesser Antilles,
NE Caribbean Sea. Journal of Micropalaeontology, 27: 177-188.
Wilson, B. 2010. Effect of hurricanes on guilds of nearshore epiphytal foraminifera, Nevis, West Indies. Journal of
Foraminiferal Research, 40: 327-343.
Wilson, B. 2011. The impact of hurricanes on epiphytal Foraminifera on rhizomes of the seagrass Thalassia testudinum,
Nevis, north-eastern Caribbean Sea. In: Seagrass: Ecology, Uses and Threats (ed Pirog, R. S.), pp. 117-138, Nova Science
Publishers, Hauppage, New York, USA.
Wilson, B., Orchard, K. & Phillip, J. 2012. SHE Analysis for Biozone Identification among foraminiferal sediment
assemblages on reefs and in associated sediment around St. Kitts, Eastern Caribbean Sea, and its environmental
significance. Marine Micropaleontology, 82-83: 38-45.
Wilson, B. & Ramsook, A. 2007. Population densities and diversities of epiphytal foraminifera on nearshore substrates,
Nevis, West Indies Journal of Foraminiferal Research, 37: 213-222.
Wilson, B. & Wilson, J. I. 2011. Shoreline foraminiferal thanatacoenoses around five eastern caribbean islands and their
environmental and biogeographic implications. Continental Shelf Research, 31: 857-866.


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