Rapid fluctuations in mid-latitude siliceous plankton production during the Middle Eocene Climatic Optimum (ODP Site 1051, western North Atlantic)

Witkowski, Jakub; Bohaty, Steven M; Edgar, Kirsty M.; Harwood, David M.

doi:10.1016/j.marmicro.2014.01.001

Cited by 44 publications

(45 citation statements)

References 57 publications

(95 reference statements)

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“…40 Ma), consistent with previous interpretations (Arditto, 1995). The MECO is a ∼ 500 kyr warming event that may be associated with sea-level rise (Sluijs et al, 2013;Witkowski et al, 2014), and in the AAG this interval is associated with the thermophilic Maslin Bay flora (McGowran and Hill, 2015) and neritic carbonates in the west (e.g., McGowran et al, 2004).…”

Section: Latrobe-1 Pollen and Sporessupporting

confidence: 88%

Identification of the Paleocene–Eocene boundary in coastal strata in the Otway Basin, Victoria, Australia

Frieling

Huurdeman

Rem

et al. 2018

J. Micropalaeontol.

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Abstract. Detailed, stratigraphically well-constrained environmental reconstructions are available for Paleocene and Eocene strata at a range of sites in the southwest Pacific Ocean (New Zealand and East Tasman Plateau; ETP) and Integrated Ocean Discovery Program (IODP) Site U1356 in the south of the Australo-Antarctic Gulf (AAG). These reconstructions have revealed a large discrepancy between temperature proxy data and climate models in this region, suggesting a crucial error in model, proxy data or both. To resolve the origin of this discrepancy, detailed reconstructions are needed from both sides of the Tasmanian Gateway. Paleocene-Eocene sedimentary archives from the west of the Tasmanian Gateway have unfortunately remained scarce (only IODP Site U1356), and no well-dated successions are available for the northern sector of the AAG. Here we present new stratigraphic data for upper Paleocene and lower Eocene strata from the Otway Basin, southeast Australia, on the (north)west side of the Tasmanian Gateway. We analyzed sediments recovered from exploration drilling (Latrobe-1 drill core) and outcrop sampling (Point Margaret) and performed high-resolution carbon isotope geochemistry of bulk organic matter and dinoflagellate cyst (dinocyst) and pollen biostratigraphy on sediments from the regional lithostratigraphic units, including the Pebble Point Formation, Pember Mudstone and Dilwyn Formation. Pollen and dinocyst assemblages are assigned to previously established Australian pollen and dinocyst zonations and tied to available zonations for the SW Pacific. Based on our dinocyst stratigraphy and previously published planktic foraminifer biostratigraphy, the Pebble Point Formation at Point Margaret is dated to the latest Paleocene. The globally synchronous negative carbon isotope excursion that marks the Paleocene-Eocene boundary is identified within the top part of the Pember Mudstone in the Latrobe-1 borehole and at Point Margaret. However, the high abundances of the dinocyst Apectodinium prior to this negative carbon isotope excursion prohibit a direct correlation of this regional bio-event with the quasi-global Apectodinium acme at the PaleoceneEocene Thermal Maximum (PETM; 56 Ma). Therefore, the first occurrence of the pollen species Spinizonocolpites prominatus and the dinocyst species Florentinia reichartii are here designated as regional markers for the PETM. In the Latrobe-1 drill core, dinocyst biostratigraphy further indicates that the early Eocene (∼ 56-51 Ma) sediments are truncated by a ∼ 10 Myr long hiatus overlain by middle Eocene (∼ 40 Ma) strata. These sedimentary archives from southeast Australia may prove key in resolving the model-data discrepancy in this region, and the new stratigraphic data presented here allow for detailed comparisons between paleoclimate records on both sides of the Tasmanian Gateway.

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Section: Latrobe-1 Pollen and Sporessupporting

confidence: 88%

Identification of the Paleocene–Eocene boundary in coastal strata in the Otway Basin, Victoria, Australia

Frieling

Huurdeman

Rem

et al. 2018

J. Micropalaeontol.

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“…However, pronounced changes are evident in the accumulation rate of benthic and planktonic foraminifera during and after the MECO (Figures c and d). Benthic foraminiferal numbers and, accordingly, BFARs are generally very low (on average 23 n/cm 2 /kyr) throughout the studied section, partially owing to dilution by abundant siliceous microfossils [ Edgar et al ., ; Norris et al ., ; Witkowski et al ., ]. Planktonic foraminifera are more abundant, resulting in higher PFARs with an average of 100–150 n/cm 2 /kyr.…”

Section: Resultsmentioning

confidence: 99%

“…Comparison of our results from ODP Site 1051 with the relative abundance of radiolarians in the total siliceous microfossil assemblages [ Witkowski et al ., ] from the same site. HPI‐1 is reflected by an increase of radiolarians, suggesting a synchronous increase of primary and export production.…”

Section: Resultsmentioning

confidence: 99%

Episodes of intensified biological productivity in the subtropical Atlantic Ocean during the termination of the Middle Eocene Climatic Optimum (MECO)

et al. 2015

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The Middle Eocene Climatic Optimum (MECO) is an~500 kyr interval of pronounced global warming from which the climate system recovered in <50 kyr. The deep-sea sedimentary record can provide valuable insight on the marine ecosystem response to this protracted global warming event and consequently on the ecological changes during this time. Here we present new benthic foraminiferal assemblage data from Ocean Drilling Program Site 1051 in the subtropical North Atlantic, spanning the MECO and post-MECO interval (41.1 to 39.5 Ma). We find little change in the species composition of benthic foraminiferal assemblages during the studied interval, suggesting that the rate of environmental change was gradual enough that these organisms were able to adapt. However, we identify two transient intervals associated with peak warming (higher-productivity interval (HPI)-1; 40.07-39.96 Ma) and shortly after the MECO (HPI-2; 39.68-39.55 Ma), where benthic foraminiferal accumulation rates increase by an order of magnitude. These HPIs at Site 1051 appear to coincide with intervals of strengthened productivity in the Tethys, Southern Ocean, and South Atlantic, and we suggest that an intensified hydrological cycle during the climatic warmth of the MECO was responsible for eutrophication of marine shelf and slope environments.

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“…Surface‐water eutrophy during the EECO at the studied site seems also supported by the early Eocene calcareous nannofossil assemblages that were dominated by Coccolithus pelagicus (Mita, ), a taxon with affinities to warm and eutrophic surface waters (e.g., Agnini et al, , , ; Dedert et al, ; Fornaciari et al, ; Newsam et al, ; Perch‐Nielsen, ; Tremolada & Bralower, ). Interestingly, high‐productivity intervals characterized by increased in siliceous plankton were recorded at Site 1051 (Moebius et al, ; Witkowski et al, ) at the peak of Middle Eocene Climatic Optimum, a longer‐lived warming event of ~500 kyr that occurred at ~40 Ma (e.g., Bohaty & Zachos, ; Bohaty et al, ). The eutrophication in the slope of the adjacent North American continental margin has been considered as triggered by intensified hydrological cycle during the climatic warmth of the Middle Eocene Climatic Optimum, leading to an increase in riverine input into the ocean (Moebius et al, ; Witkowski et al, ).…”

Section: Discussionmentioning

confidence: 99%

Did Photosymbiont Bleaching Lead to the Demise of Planktic ForaminiferMorozovellaat the Early Eocene Climatic Optimum?

et al. 2017

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The symbiont‐bearing mixed‐layer planktic foraminiferal genera Morozovella and Acarinina were among the most important calcifiers of early Paleogene tropical–subtropical oceans. A marked and permanent switch in the abundance of these genera is known to have occurred at low‐latitude sites at the beginning of the Early Eocene Climatic Optimum (EECO), such that the relative abundance of Morozovella permanently and significantly decreased along with a progressive reduction in the number of species; concomitantly, the genus Acarinina almost doubled its abundance and diversified. Here we examine planktic foraminiferal assemblages and stable isotope compositions of their tests at Ocean Drilling Program Site 1051 (northwest Atlantic) to detail the timing of this biotic event, to document its details at the species level, and to test a potential cause: the loss of photosymbionts (bleaching). We also provide stable isotope measurements of bulk carbonate to refine the stratigraphy at Site 1051 and to determine when changes in Morozovella species composition and their test size occurred. We demonstrate that the switch in Morozovella and Acarinina abundance occurred rapidly and in coincidence with a negative carbon isotope excursion known as the J event (~53 Ma), which marks the start of the EECO. We provide evidence of photosymbiont loss after the J event from a size‐restricted δ 13 C analysis. However, such inferred bleaching was transitory and also occurred in the acarininids. The geologically rapid switch in planktic foraminiferal genera during the early Eocene was a major evolutionary change within marine biota, but loss of photosymbionts was not the primary causal mechanism.

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Rapid fluctuations in mid-latitude siliceous plankton production during the Middle Eocene Climatic Optimum (ODP Site 1051, western North Atlantic)

Cited by 44 publications

References 57 publications

Identification of the Paleocene–Eocene boundary in coastal strata in the Otway Basin, Victoria, Australia

Identification of the Paleocene–Eocene boundary in coastal strata in the Otway Basin, Victoria, Australia

Episodes of intensified biological productivity in the subtropical Atlantic Ocean during the termination of the Middle Eocene Climatic Optimum (MECO)

Did Photosymbiont Bleaching Lead to the Demise of Planktic ForaminiferMorozovellaat the Early Eocene Climatic Optimum?

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