In Praise of High Resolution Ecostratigraphy!

or

The Palaeoenvironmental Significance of Foraminifera in the Upper Quaternary of ODP Hole 1006A,

Santaren Strait, Offshore Western Bahama PlatformProfessor Brent Wilson FGSPetroleum 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 boundariesDo 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.

Light blue areas, shoal water

Dark blue areas, bathyal to abyssal water

Study area at left

The carbonate Bahama Platform

When a carbonate platform sheds sediment into adjacent basin during highstands of sea level

Frequent during Quaternary interglacials

What is highstand shedding?

What is a drift deposit?

Anselmetti F S et al. Geological Society of America Bulletin 2000;112:829-844

•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

Location of the Santaren Drift

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 lithologySubunit 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 claysand 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.

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

Onwards to the (reefal) forams!

26 ka

•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?

Shallow water foram diversity in ODP Hole 1006A

  Axis 1 Axis 2 Axis 3 Axis 4 Axis 5 Axis 6Eigenvalue 5.64 2.98 1.80 1.61 1.39 1.11% variance 28.21 14.93 8.98 8.03 6.93 5.57Angulogerina occidentalis 0.60 –0.3127 0.23 –0.1671 0.15 –0.02902Articulina pacifica –0.8651 –0.2085 0.09 –0.09609 –0.08816 0.04Asterigerina carinata –0.512 –0.4776 0.32 –0.07396 –0.2359 –0.3825Brizalina paula 0.58 0.12 –0.4187 –0.04684 –0.3565 –0.1906Brizalina subexcavata 0.42 –0.1827 0.19 –0.1715 0.68 0.17Caribeanella polystoma –0.6941 –0.4953 0.12 –0.1611 –0.2789 0.05Cibicides advena –0.1555 0.53 0.49 0.22 -0.08 –0.02026Elphidium translucens –0.01369 –0.5411 0.17 0.52 0.24 –0.03379Miliolinella circularis –0.6195 –0.2757 –0.2056 –0.02673 –0.06301 0.54

Planulina foveolata –0.4204 0.60 0.44 0.40 0.001885 –0.06834Quinqueloculina auberina –0.3422 –0.2373 0.09 –0.3837 0.22 –0.3613Quinqueloculina lamarckiana –0.5023 –0.2015 –0.3391 0.32 0.36 –0.2679Quinqueloculina poeyana –0.5896 –0.1575 –0.1596 0.20 0.38 –0.3039

Rosalina bahamaensis –0.7992 –0.3493–

0.008335 –0.1915 –0.1791 0.23Rosalina globularis 0.12 –0.3549 –0.2606 0.50 –0.3289 –0.2711Sagrina pulchella 0.53 –0.5618 0.08 0.32 –0.2002 0.08Sagrina pulchella primitiva 0.30 –0.5998 0.50 0.16 0.06 0.20Sigmavirgulina tortuosa 0.78 –0.2768 0.19 0.20 –0.1559 0.08Siphonina pulchra –0.4708 0.41 0.46 0.22 –0.09342 0.04Triloculina bermudezi –0.3655 0.13 –0.4401 0.48 0.16 0.35

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 foraminiferaSpecies Pearson's r

Globocassidulina subglobosa 0.609Sigmoilopsis schlumbergeri 0.584Siphonina bradyana 0.511Sphaeroidina bulloides 0.499Discanomalina semipunctata 0.420Cibicidoides robertsonianus 0.419Cibicidoides bradyi 0.412Cassidulina crassa 0.407Hoeglundina elegans -0.402Cylindroclavulina bradyi -0.419Uvigerina laevis -0.422Globocassidulina punctata -0.426Gyroidinoides neosoldanii -0.434Cibicidoides umbonatus -0.463Bigenerina irregularis -0.529Melonis baarleeanus -0.587Lenticulina rotulata -0.616Cassidulina laevigata -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 zeroSlope 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

“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)

A Warning!

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 sedimentHearty 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?

What of the original research question? The Upper Quaternary of ODP Hole 994C – a.k.a. what I did last semester.

3 4 oN

32 oN

CapeHatte ras

U SA

76oW78oW80oW

*Site 994

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00 5 10 15 20 25 0 5 1 0 2 01 5

Globocassidulina obtusa Uvigerina spp.

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I

II

III

IV

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A

B

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0 102 4 6 8 12 14 16Epistominella takayanagii

0 1 2 3 4 18Elphidium excavatum

Kp = 5.6%

Kp = 12.9%

Kp = 18.1%

Kp = 9.3%

Kp = 11.9%

Kp = 3.7%

A. Displaced genera and species B. In situ genera and species

i

ii

iii

iv

v

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 1006ASo, two events in ODP 1006A.

Flux of reefal foraminifera highest in MIS 8-9Change 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)

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.

Questions?