Origin of High Productivity in the Pliocene of the Florida Platform: Evidence From Stable Isotopes and Trace Elements

Tao, Kai; Grossman, Ethan L.

doi:10.2110/palo.2010.p10-058r

Cited by 19 publications

(18 citation statements)

References 39 publications

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“…Upwelling has been inferred for the Tamiami Formation on the basis of abundant and diverse molluscs (e.g., Allmon 1988Allmon , 1993 and the presence of cormorant skeletons (Emslie 1992). However, recent high resolution isotopic and Sr/Ca analyses of gastropods suggests that the nutrient-rich conditions were derived from freshwater inputs (Tao and Grossman 2010). Salinity may have influenced zooid sizes although available evidence suggests the effect of salinity is roughly half that of temperature (O'Dea and Okamura 1999).…”

Section: Discussionmentioning

confidence: 99%

Evidence of El Niño/La Niña–Southern Oscillation Variability in the Neogene-Pleistocene of Panama Revealed by a New Bryozoan Assemblage-Based Proxy

Okamura¹,

O’Dea²,

Taylor³

et al. 2013

BMS

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Here we explore how fossil cheilostome bryozoans can demonstrate El Niño/La Niña-Southern Oscillation (ENSO) variability in ancient tropical environments of the tropical eastern Pacific and southwestern Caribbean when used collectively to produce frequency distributions of estimates of mean annual ranges in temperature (MARTs) via zooid-size MART analysis (zs-MART). The approach is based on linking variation in the sizes of constituent zooids in bryozoan colonies with the temperature regimes in which the zooids developed. The shapes of frequency distributions of zs-MART estimates from modern environments are consistent with known upwelling and non-upwelling environments and ENSO variability. Data from fossil colonies provide evidence that ENSO variability characterized Caribbean environments in what is now present-day Panama during the Miocene and Pliocene (thus supporting neither a permanent El Niño nor a permanent La Niña in the Pliocene), but not the Pleistocene after the Isthmus of Panama closed. Western Atlantic data provide further evidence for ENSO variability in the Pliocene of Florida but not Virginia. Our study shows the potential of bryozoan assemblages to infer variation in seasonal regimes thus encouraging the further development of this proxy for inferring ENSO variability.

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Section: Discussionmentioning

confidence: 99%

Evidence of El Niño/La Niña–Southern Oscillation Variability in the Neogene-Pleistocene of Panama Revealed by a New Bryozoan Assemblage-Based Proxy

Okamura¹,

O’Dea²,

Taylor³

et al. 2013

BMS

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“…For the cormorant bed we tend to infer the upwelling to have been intermittent. Stable isotope evidence found in molluscan shells, however, remains inconclusive with regard to the origin of high productivity Tao and Grossman, 2010). In contrast to earlier work, we use a positive correlation of bulk δ 18 O and bulk δ 13 C as a signature of upwelling (Figs.…”

Section: Upwelling As a Driver Of High Skeletal Productivity?mentioning

confidence: 98%

Upwellings mitigated Plio-Pleistocene heat stress for reef corals on the Florida platform (USA)

et al. 2016

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Abstract. The fast growing calcareous skeletons of zooxanthellate reef corals (z corals) represent unique environmental proxy archives through their oxygen and carbon stable isotope composition (δ 18 O, δ 13 C). In addition, the accretion of the skeleton itself is ultimately linked to the environment and responds with variable growth rates (extension rate) and density to environmental changes. Here we present classical proxy data (δ 18 O, δ 13 C) in combination with calcification records from 15 massive z corals. The z corals were sampled from four interglacial units of the Florida carbonate platform (USA) dated approximately 3.2, 2.9, 1.8 and 1.2 Ma (middle Pliocene to early Pleistocene). The z corals (Solenastrea, Orbicella, Porites) derive from unlithified shallow marine carbonates and were carefully screened for primary preservation suited for proxy analysis. We show that skeletal accretion responded with decreasing overall calcification rates (decreasing extension rate but increasing density) to warmer water temperatures. Under high annual water temperatures, inferred from sub-annually resolved δ 18 O data, skeletal bulk density was high, but extension rates and overall calcification rates were at a minimum (endmember scenario 1). Maximum skeletal density was reached during the summer season giving rise to a growth band of high density within the annually banded skeletons ("high density band", HDB). With low mean annual water temperatures (endmember scenario 2), bulk skeletal density was low but extension rates and calcification rates reached a maximum, and under these conditions the HDB formed during winter. Although surface water temperatures in the Western Atlantic warm pool during the interglacials of the late Neogene were ∼ 2 • C higher than they are in the present day, intermittent upwelling of cool, nutrient-rich water mitigated water temperatures off southwestern Florida and created temporary refuges for z coral growth. Based on the sub-annually resolved δ 18 O and δ 13 C records, the duration of the upwelling episodes causing the endmember 2 conditions was variable and lasted from a few years to a number of decades. The episodes of upwelling were interrupted by phases without upwelling (endmember 1) which lasted for at least a few years and led to high surface water temperatures. This variable environment is likely one of the reasons why the coral fauna is dominated by the eurytopic genus Solenastrea, also a genus resistant to high turbidity. Over a period of ∼ 50 years, the oldest sub annually resolved proxy record available (3.2 Ma) documents a persistent occurrence of the HDB during winter. In contrast, the HDB forms in summer in modern z corals from the Florida reef tract. We suggest this difference should be tested as being the expression of a tendency towards decreasing interglacial upwelling since the middle Pliocene. The number of z coral sclerochronological records for the Plio-Pleistocene is still rather low, however, and requires more data and an improved resolution, through records from...

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“…Combined oxygen and carbon stable isotope data (δ 18 O, δ 13 C) of diagenetically pristine mollusks and z corals from the platform sediments reflect the complexity of the depositional setting including brackish to hypersaline and well-mixed, open marine environments Lloyd, 1969;Tao and Grossman, 2010). The reasons for high benthic carbonate productivity by mollusks during the Plio-Pleistocene is controversial, and has been suggested to be due to high nutrient concentrations resulting from freshwater input (Tao and Grossman, 2010) or upwelling (Allmon, 2001;Allmon et al, 1995;Brachert et al, 2016;Emslie and Morgan, 1994;Jones and Allmon, 1995 (Brachert et al, 2016). In contrast, seasonal SST variability (∼ 7 • C) inferred from cyclic δ 18 O variations of the fossils is more independent of assumptions of δ 18 O water .…”

Section: The Florida Platform During the Plio-pleistocene Interglacialsmentioning

confidence: 99%

Low Florida coral calcification rates in the Plio-Pleistocene

et al. 2016

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Abstract. In geological outcrops and drill cores from reef frameworks, the skeletons of scleractinian corals are usually leached and more or less completely transformed into sparry calcite because the highly porous skeletons formed of metastable aragonite (CaCO 3 ) undergo rapid diagenetic alteration. Upon alteration, ghost structures of the distinct annual growth bands often allow for reconstructions of annual extension (= growth) rates, but information on skeletal density needed for reconstructions of calcification rates is invariably lost. This report presents the bulk density, extension rates and calcification rates of fossil reef corals which underwent minor diagenetic alteration only. The corals derive from unlithified shallow water carbonates of the Florida platform (south-eastern USA), which formed during four interglacial sea level highstands dated approximately 3.2, 2.9, 1.8, and 1.2 Ma in the mid-Pliocene to early Pleistocene. With regard to the preservation, the coral skeletons display smooth growth surfaces with minor volumes of marine aragonite cement within intra-skeletal porosity. Within the skeletal structures, voids are commonly present along centres of calcification which lack secondary cements. Mean extension rates were 0.44 ± 0.19 cm yr −1 (range 0.16 to 0.86 cm yr −1 ), mean bulk density was 0.96 ± 0.36 g cm −3 (range 0.55 to 1.83 g cm −3 ) and calcification rates ranged from 0.18 to 0.82 g cm −2 yr −1 (mean 0.38 ± 0.16 g cm −2 yr −1 ), values which are 50 % of modern shallow-water reef corals. To understand the possible mechanisms behind these low calcification rates, we compared the fossil calcification rates with those of modern zooxanthellate corals (z corals) from the Western Atlantic (WA) and Indo-Pacific calibrated against sea surface temperature (SST). In the fossil data, we found a widely analogous relationship with SST in z corals from the WA, i.e. density increases and extension rate decreases with increasing SST, but over a significantly larger temperature window during the Plio-Pleistocene. With regard to the environment of coral growth, stable isotope proxy data from the fossil corals and the overall structure of the ancient shallow marine communities are consistent with a well-mixed, open marine environment similar to the present-day Florida Reef Tract, but variably affected by intermittent upwelling. Upwelling along the platform may explain low rates of reef coral calcification and inorganic cementation, but is too localised to account also for low extension rates of Pliocene z corals throughout the tropical WA region. Low aragonite saturation on a more global scale in response to rapid glacialinterglacial CO 2 cyclicity is also a potential factor, but PlioPleistocene atmospheric pCO 2 is generally believed to have been broadly similar to the present day. Heat stress related to globally high interglacial SST only episodically moderated by intermittent upwelling affecting the Florida platform seems to be another likely reason for low calcification rates. From these observatio...

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Origin of High Productivity in the Pliocene of the Florida Platform: Evidence From Stable Isotopes and Trace Elements

Cited by 19 publications

References 39 publications

Evidence of El Niño/La Niña–Southern Oscillation Variability in the Neogene-Pleistocene of Panama Revealed by a New Bryozoan Assemblage-Based Proxy

Evidence of El Niño/La Niña–Southern Oscillation Variability in the Neogene-Pleistocene of Panama Revealed by a New Bryozoan Assemblage-Based Proxy

Upwellings mitigated Plio-Pleistocene heat stress for reef corals on the Florida platform (USA)

Low Florida coral calcification rates in the Plio-Pleistocene

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