Mid-Cretaceous cooling in the North and South Atlantic; climate instability and marine biotic crisis

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http://abstractsearch.agu.org/meetings/2012/FM/PP31A-2005.html
Author(s): McAnena, A.; Wagner, Thomas; Herrle, Jens O.; Talbot, H. M.; Hofmann, Peter
Author Affiliation(s): Primary:
University of Koln, Mineralogy and Geology, Cologne, Germany
Other:
Newcastle University, United Kingdom
Goethe University Frankfurt, Germany
Volume Title: AGU 2012 fall meeting
Source: American Geophysical Union Fall Meeting, Vol.2012; American Geophysical Union 2012 fall meeting, San Francisco, CA, Dec. 3-7, 2012. Publisher: American Geophysical Union, Washington, DC, United States
Note: In English
Summary: New evidence from both the North and South Atlantic suggests that during the Late Aptian, significant periods of global cooling associated with short-term climate instability resulted in a severe biotic crisis affecting nannofossils, foraminifera and reef builders. We observe Late Aptian long term cooling at the Mazagan Plateau (DSDP Site 545) over a period of 1.5 million years characterised by decreasing sea surface temperatures from ≈32.5 to ≈27.5°C (based on TEX86 estimates) and a long term positive isotope excursion (1 ppm to 2.5 ppm). Cooling is concurrent to a dramatic decrease in the abundance of Nannoconus spp. and planktic foraminifera at Site 545 and also a dramatic decline of reef builders in the Caribbean and Western Tethys region. We note a number of short term temperature and carbon excursions including several hyperthermal events superimposed on the long term cooling. We associate the trigger of the observed climate shifts in the western North Atlantic to both increased global carbon burial and fluctuations in the flow of warm Tethyan waters through the Proto-Gibraltar Strait. Preliminary data from DSDP Site 511 (Falkland Plateau) also reveal a Late Aptian decrease in sea surface temperatures of approximately 4°C (ranging ≈31 to 27°C) associated with a positive organic carbon isotope excursion (-24 to -22 ppm) and a concurrent extinction of planktic foraminifera. We conclude that Late Aptian cooling was a global phenomenon linked to increased global carbon burial with superimposed regional forcing mechanisms. The new data from Site 545 and 511 support a causal connection between cooling and biotic crises, although the role of short-term climate instability remains to be explored further.
Year of Publication: 2012
Research Program: DSDP Deep Sea Drilling Project
IPOD International Phase of Ocean Drilling
Key Words: 12 Stratigraphy, Historical Geology and Paleoecology; Aptian; Atlantic Ocean; Climate change; Cretaceous; DSDP Site 511; DSDP Site 545; Deep Sea Drilling Project; Foraminifera; IPOD; Invertebrata; Leg 71; Leg 79; Lower Cretaceous; Marine environment; Mazagan Plateau; Mesozoic; Microfossils; Middle Cretaceous; North Atlantic; Paleo-oceanography; Paleoclimatology; Paleoenvironment; Paleogeography; Protista; Reconstruction; Sea-surface temperature; South Atlantic
Coordinates: S510017 S510017 W0465818 W0465818
N333951 N333952 W0092152 W0092153
Record ID: 2014044817
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