Absolute age of the Cretaceous-Paleogene boundary at the precessional scale

Author(s): Hinnov, Linda A.; Locklair, Robert; Ogg, James G.; Huret, Emilia
Author Affiliation(s): Primary:
Johns Hopkins University, Morton K. Blaustein Department of Earth and Planetary Sciences, Baltimore, MD, United States
Other:
Purdue University, United States
Volume Title: Geological Society of America, 2008 annual meeting
Source: Abstracts with Programs - Geological Society of America, 40(6), p.283; Geological Society of America, 2008 annual meeting, Houston, TX, Oct. 5-9, 2008. Publisher: Geological Society of America (GSA), Boulder, CO, United States. ISSN: 0016-7592 CODEN: GAAPBC
Note: In English. 1 refs.
Summary: The absolute age of the Cretaceous/Paleogene (K/P) boundary has recently undergone a re-evaluation through integration of new chronostratigraphy, high-precision geochronology and astrochronology. Results now point to a boundary age of 65.957 Ma with an uncertainty that could be as low as ± 0.01 myr (1). There are, however, doubts about the astrochonological estimates, which are based on matching sediment cycle modulations to orbital eccentricity on the Paleogene side of the boundary. Low sediment accumulation and/or disturbance immediately above the boundary in the studied sections introduces uncertainty into the matching that could be as large as ± 0.4 myrs. To address this problem, we assessed cycling from the Maastrichtian side of the boundary, where sedimentation rates are generally much higher and clearly resolve precession-scale cyclicity. Comparison of cyclostratigraphic records (carbonate content, magnetic susceptibility, luminosity, gamma log, FMI, Fe concentration) from multiple sites (ODP Legs 191B, 207, 208; DSDP Sites 516F, 525A, 528; Zumaya) to the La2004 precession index (PI) (2) shows a consistent match between the amplitude modulations of the PI and the recorded precession cycles leading up to the boundary, provisionally set to 66 Ma. An unusual set of low-amplitude precession cycles between 66.45-66.35 Ma in the PI can be recognized in all of the examined records. Anchoring analogous low-amplitude recorded cycles to this interval, and counting the succeeding cycles upward results in an age for the K/P boundary that is between 66.05-66.15 Ma, only slightly older than (1). We discuss the uncertainties in our bottom-up estimates, and assess the utility of this proposed precession-based scaling in providing precise correlation horizons for other events (impact, extinctions, magnetic reversals) associated with this famous stratigraphic interval. References: 1, Kuiper et al., 2008, Science, 320:500; 2, Laskar et al., 2004, Astron. Astrophys. 428: 261.
Year of Publication: 2008
Research Program: DSDP Deep Sea Drilling Project
IPOD International Phase of Ocean Drilling
ODP Ocean Drilling Program
Key Words: 12 Stratigraphy, Historical Geology and Paleoecology; Absolute age; Atlantic Ocean; Cenozoic; Chronostratigraphy; Cretaceous; Cycles; DSDP Site 516; DSDP Site 525; DSDP Site 528; Dates; Deep Sea Drilling Project; Demerara Rise; Equatorial Atlantic; High-resolution methods; IPOD; K-T boundary; Leg 191; Leg 207; Leg 208; Leg 72; Leg 74; Lower Paleocene; Magnetic properties; Magnetic susceptibility; Mesozoic; North Atlantic; North Pacific; Northwest Atlantic; Northwest Pacific; Ocean Drilling Program; Pacific Ocean; Paleocene; Paleogene; Paleomagnetism; Precession; Rio Grande Rise; South Atlantic; Stratigraphic boundary; Tertiary; Upper Cretaceous; Walvis Ridge; Well logs; West Atlantic; West Pacific
Coordinates: N120000 N420000 E1600000 E1430000
S290415 S290414 E0025908 E0025907
S301636 S301635 W0351706 W0351707
Record ID: 2012054748
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