© ICDP, the International Continental Scientific Drilling Program, 1996-2020

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Tanzania Onshore Paleogene Integrated Coring (TOPIC)

Africa, Tanzania

new full-proposal: ICDP-2015/03
for the funding-period starting 2015-01-15
by D. Graham Pearson, Paul N. Pearson, Hudson Wellington
Abstract
We propose to recover a 1200 m section through hemipelagic marine mudstones (Kilwa Group) that are now emplaced on land in southern coastal Tanzania to 1) generate a stratigraphic record of tropical climatic and biotic change through the Eocene, and 2) quantify microbial activity and biomass at depth in a relatively monotonous and impermeable lithology. Kilwa Group sediments are well known for their exquisitely microfossils and organic biomarkers, and have proven potential for a wide range of marine and terrestrial paleoclimate proxies, allowing us to reconstruct conditions in the low-latitude ocean, atmosphere, and on the adjacent African continent. Drilling targets include critical intervals of extreme climate and major climate change including the Paleocene/Eocene Thermal Maximum, the Early and Middle Eocene Climatic Optima, the Middle/Late Eocene biotic turnover, and the Eocene / Oligocene Transition. We will produce new high-resolution quantitative records of atmospheric carbon dioxide and sea surface and sub-surface temperatures with quantitative constraints on global ice volumes. Data will be used to test General Circulation Models with Eocene paleogeography and greenhouse forcing. This will allow us to assess model performance at reconstructing a range of climate states. The cores will provide a world-class reference section for Eocene integrated stratigraphy and geochronology. For the first time we will study the microbial biosphere to > 1 km depth in marine mudstones that are now emplaced on land. Exceptional preservation of carbonate microfossils suggests that pore fluid migration has been minimal for tens of millions of years, from which we predict very much lower levels of microbial activity than is found at comparable depths in other rock types. This will provide a baseline for biological activity in geologically quiescent sub-surface environments, advancing our knowledge of subsurface community dynamics with relevance to organic carbon maturation studies and long-term toxic and nuclear waste disposal. The area of the proposed drill-site is well-understood from surface outcrop mapping and previous shallow drilling. New seismic survey data confirm that it is a large fault-bounded structural block, gently dipping seaward with internal structural integrity and no significant traps, folding, or faulting in the top ~2000 m. The proposed drill-site and alternate are in spare land in sparsely populated areas with access to roads, hence we anticipate a relatively straightforward operations in comparison to many other ICDP projects. The proposal is informally linked to Integrated Ocean Drilling Program Full Proposal 778 (graded 'excellent' by IODP) and has complementary scientific objectives.
Scientific Objectives
  • Current atmospheric CO2 concentrations are similar to those of the Pliocene and predicted to become comparable to those of the early Cenozoic within the coming centuries (IPCC,
  • 2013). As the planet responds to anthropogenic greenhouse gas emissions it is important to understand climate forcing and response in Earth's past, especially greenhouse episodes. This information will advance understanding of the major societal challenge of climate change. Our proposal will address the following specific questions: How did atmospheric CO2 and global temperature co-vary during previous intervals of global warmth? How extreme did climatic conditions become in the tropics, in the ocean and on land? What was the response of the marine and terrestrial biota to extreme climate states and intervals of climate change? Is the paleoclimate forcing and response we infer from the sediment record consistent with the predictions of General Circulation Models (GCMs) that are also used to predict the future? In addition we will sample the deep biosphere to > 1 km in relatively montonous impermeable mudstones for the first time to test the hypothesis that restricted fluid flow causes very low levels of microbial biomass and metabolic activity at depth
Keywords
Africa, Eocene, ICDP-2015/03, Microbiology, Paleoclimate, Tanzania, TOPIC
Location
Africa, Tanzania: -7.00000, 34.00000

© ICDP, the International Continental Scientific Drilling Program, 1996-2020

www.icdp-online.org