Paul Bown - IODP Expedition 320 participation

Lead Research Organisation: University College London
Department Name: Earth Sciences


1. Intercalibration of stratigraphic datums from the Paleogene PEAT splice Undertake shipboard and post-cruise calcareous nannofossil biostratigraphy for the Eocene-Miocene interval and integrate these data with those from other PEAT stratigraphers. The completion of a astronomically calibrated Paleogene stratigraphic 'mega-splice' is an Expeditions 320/321 primary objective. 2. Calcareous nannofossil evolution through Eocene hyperthermals and the Eocene climatic optimum The early to middle Eocene saw a rise in nannofossil diversity to a Cenozoic maximum. I will investigate the timing and structure of this increase and examine whether climatic shifts played a significant role in the evolution of the oceanic plankton at this time. If early Eocene hyperthermal intervals are recovered I will investigate the nannofossil response at high resolution to test for the forcing effects of temperature and/or ocean chemistry changes (e.g. acidification) on nannofossil abundance, diversity and evolutionary rates. 3. Climate, carbonate accumulation and nannofossil evolution through the middle to late Eocene Carbonate and silica accumulation events have been identified in previous records from the equatorial Pacific and linked to changes in planktonic productivity and global climate shifts. This time interval also saw a precipitous decline in the diversity of nannofossils from which the group has arguably never completely recovered. I will generate quantitative nannofossil abundance and diversity records on short and long timescales in order to examine the relationships between nannofossil productivity and evolution, carbonate accumulation and paleoclimate/paleoceanography. In detail, I am interested in the nannofossil record across the Middle Eocene climatic optimum (MECO; 42Ma) and the biogenic accumulation and carbonate compensation depth (CCD) events that follow, and precede the Eocene/Oligocene transition (48-34Ma). I will also investigate the nature of nannofossil preservation as sites approach the CCD, in particular its influence on preserved diversity and proxy records. 4. Eocene-Oligocene transition (EOT) - investigating links between ocean chemistry and plankton evolution A major restructuring in plankton ecosystems across the EOT suggests that the expansion of Antarctic ice sheets is coincident with a significant perturbation in low-latitude surface ocean environments. Evidence from calcareous nannofossil assemblages indicates that this may be due to a widespread increase in nutrient availability. A marked shoaling of the CCD immediately prior to the EOT has hampered the production of a comparable record from deep-sea sediments. We propose to measure absolute nannofossil species abundances and, combined with the cyclostratigraphic age model, quantify nannofossil accumulation rates across the EOT. We would also actively collaborate with PEAT scientists in the production of the full range of carbonate, silica, nannofossil and foraminiferal accumulation rates. 5. Early Miocene glaciation (Mi-1) and the plankton ecosystem The relatively short but significant early Miocene glacial episode, Mi-1, is in some ways similar to the EOT climate event. There has, however, been little observed response within planktonic ecosystems to Mi-1. We would apply the methodology used in objective 4 to Mi-1 (PEAT-6C). This is an extension of objective 4 and we will collaborate with PEAT nannofossil biostratigraphers who have this interval as a primary objective.


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Description Coring

IODP Expedition 320 cored 16 holes at 6 sites (Holes U1331A-U1331C, U1332A-U1332C, U1333A-U1333C, U1334A-U1334C, U1335A, U1335B, U1336A, and U1336B) as part of the 'Pacific Equatorial Age Transect' (PEAT) program. The related IODP Expedition 321 recovered a further seven holes at two sites (Holes U1337A-U1337D and Holes

U1338A-U1338C). The combined PEAT programme retrieved a total of 712 cores, coring 6322 m and recovering 6141 m (97.1% core recovery). By drilling a series of sites that follow the position of the palaeo-equator and a limited latitudinal and depth transect, we recovered cores that allow us to address the combined PEAT objectives (see Scientific Prospectus at

Shipboard Science

As one of the shipboard micropalaeontologists my major role was to provide real-time biostratigraphic data, which enabled strategic decisions on drilling strategy and planning of research and sampling. Around 1000 samples were processed and analysed for calcareous nannofossil content and integrated with other microfossil and palaeomagnetic data. The age dating showed that the PEAT transect recovered a virtually complete composite section ranging from upper Pleistocene to lower Eocene, representing ~52 Ma of geological history. The youngest 12 million year portion of this record (middle Miocene to Recent) was only well represented at Site U1335 and elsewhere only present as a thin (5-10m) veneer of noncalcareous brown clay. The bulk of our recovered records comprise a continuous middle Miocene through lower Eocene succession of biogenic sediments with nannofossil- and radiolarian-ooze end members. Chert and porcellanite levels were present in the lower parts of Sites U1331, U1332 and U1336. At Sites U1331 and U1335, discrete turbidite beds were present containing reworked microfossils, with mixing most obvious at the former site. All the sites contribute apparently continuous successions to this composite section, and stratigraphic highlights include recovery of complete Eocene/Oligocene and Oligocene/Miocene boundaries at four sites: U1331 through U1334 and U1332 through U1336, respectively. These sections provide excellent records of biotic response to these periods of rapid environmental change in the principal phytoplanktonic and zooplankton groups as well as benthic foraminifera. The results of the shipboard science are published online as a Preliminary Report ( and the

more comprehensive Proceedings volume is in press and due later this year (2010). Summaries of shipboard activities and science written for the general public are available in blog form on the NERC Planet Earth website (
Exploitation Route The records from Exp. 320 will continue to be used as a valuable archive of equatorial ocean and climate change over the last 50 millions years.
Sectors Energy,Environment

Description Biostratigraphic and taxonomic data have been used in the web resource Nannotax
First Year Of Impact 2012
Sector Education,Energy,Environment
Impact Types Economic

Description Investigating the history of climate and life through deep sea drilling 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Public/other audiences
Results and Impact Much of our modern understanding of ocean and climate history comes from the study of deep-sea drill cores. Over the last 50 years, starting with early attempts to drill to the Moho, Deep Sea Drilling Project (DPDP), Ocean Drilling Program (ODP) and most recently Integrated Ocean Drilling Program (IODP) have brought together scientists from 24 countries to study all aspects of ocean history, and collectively this ranks as one of most significant scientific endeavours ever. The talk will provide a glimpse of life onboard the latest IODP drill ship, the JOIDES Resolution, describing the work carried out by around 100 international scientists, technicians and crew during two recent expeditions, working 12 hours a day for two months. The Pacific and Atlantic expeditions IODP Exp. 320 (March-May 2009) and 342 (June-July 2012) both focused on Paleogene science objectives, particularly the interval when climate switched from very warm Eocene 'greenhouse' conditions to the glacial climates of the Oligocene, but, as always, many surprises were encountered along the way, including beautiful examples of impact ejecta beds at the Cretaceous/Tertiary boundary and black shales of the Cretaceous. Although work is ongoing after both expeditions, I will present some of our new findings on the climate and evolutionary history of the Paleogene interval.

Public talk presented at the Festival of Geology, organised by the Geologist's Association
Year(s) Of Engagement Activity 2012