From greenhouse to icehouse; to there and back again, results from Arctic Ocean drilling

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Author(s): Brinkhuis, Henk
Author Affiliation(s): Primary:
Utrecht University, Biology, Utrecht, Netherlands
Volume Title: 2010 AAPG annual convention & exhibition; Unmasking the potential of exploration & production; abstracts
Source: Abstracts: Annual Meeting - American Association of Petroleum Geologists, Vol.2010; AAPG 2010 annual convention & exhibition, New Orleans, LA, April 11-14, 2010. Publisher: American Association of Petroleum Geologists and Society for Sedimentary Geology, Tulsa, OK, United States
Note: In English. 1 refs.
Summary: Rising atmospheric CO2 concentrations (IPCC 2007) are pushing Earth towards new "greenhouse" states, not witnessed for more than 20 million years. Earth system studies of the ancient greenhouse state of the planet, e.g., during the early Palaeogene (65-35 Ma) and/or Late Cretaceous (100-65 Ma) are therefore becoming increasingly important, and are prominent on the research agenda, as are studies of potential mechanisms underlying the transition to the lower CO2 world of the Oligocene and Neogene, or Icehouse Earth. The first-ever Arctic drilling (Arctic Coring Expedition, ACEX, aka IODP Expedition 302) provided unprecedented snapshots of Arctic climates during the greenhouse conditions, and greenhouse-icehouse transition, spanning the past ≈56 Ma. During times of ultra-greenhouse conditions (i.e., the Eocene Thermal Maxima, ETM, 1 and 2), ≈55-53 Ma ago, our dinocyst and TEX86 ratios records show the Arctic to have been near tropical with temperatures soaring to 24 °C. Meanwhile, detailed studies of this event offshore SW Africa (ODP 208) showed the impact of high CO2 in terms of ocean acidification and lysocline shoaling from ancient deep water, tropical settings, while dinoflagellate blooms were raging around the globe. Perhaps even more surprising, at levels dated ≈49 Ma, the ACEX cores yield stunning concentrations of remains of the freshwater fern Azolla suggesting that at least episodically, completely fresh surface water settings characterized the Arctic Basin. Marking the end of the warmest phase of the past 100 Ma, the Azolla event may prove to have been instrumental in the capturing of atmospheric CO2, paving the way for global cooling; a hypothesis currently tested by the 3-PhD Darwin Azolla project. While recording the past, ACEX results may be also taken to portray a possible, "business as usual" future of Earth.
Year of Publication: 2010
Research Program: DSDP Deep Sea Drilling Project
IODP Integrated Ocean Drilling Program
ODP Ocean Drilling Program
Key Words: 12 Stratigraphy, Historical Geology and Paleoecology; Acidification; Africa; Arctic Coring EXpedition; Arctic Ocean; Azolla; Carbon dioxide; Cenozoic; Cretaceous; DSDP Site 208; Deep Sea Drilling Project; Dinoflagellata; Drilling; Eocene; Expedition 302; Filicopsida; Greenhouse effect; Icehouse effect; Integrated Ocean Drilling Program; Leg 21; Lomonosov Ridge; Lord Howe Rise; Lysoclines; Mesozoic; Microfossils; Neogene; Ocean Drilling Program; Oligocene; Pacific Ocean; Paleocene-Eocene Thermal Maximum; Paleoclimatology; Paleoenvironment; Paleogene; Paleotemperature; Palynomorphs; Plantae; Pteridophyta; South Pacific; Southwest Pacific; Southwestern Africa; Tertiary; Upper Cretaceous; West Pacific
Coordinates: N875100 N875600 E1393300 E1361000
S260637 S260636 E1611317 E1611316
Record ID: 2012084935
Copyright Information: GeoRef, Copyright 2019 American Geosciences Institute. Reference includes data supplied by American Association of Petroleum Geologists, Tulsa, OK, United States