Publication Date:
2017-04-04
Description:
The Danian–Selandian (D–S) boundary has been identified for the first time in the Black Sea coast at Bjala
(Bulgaria) based on a new integrated bio-, magneto- and cyclostratigraphic study. Several correlation criteria
as established for the basal Selandian GSSP from Zumaia (Basque Basin) are evaluated. Noteworthy, is the
almost complete lack of calcareous nannoplankton species Braarudosphaera bigelowi in the Bulgarian sections,
a sharp decrease of which was indicated as suitable criteria for defining the D–S boundary as it occurred both
at Zumaia and in the classical locations of the North Sea basin. Conversely, the second evolutionary radiation
of the calcareous nannofossil genus Fasciculithus together with the occurrence of Fasciculithus tympaniformis
that define the NP4/NP5 zonal boundary seem to be reliable criteria to approximate the D–S boundary. In
detail, however, the best approach is to integrate biostratigraphic data within a magnetostratigraphic and/or
cyclostratigraphic framework. Refinements on the placement of chron C27n at Zumaia and robust bed-by-bed
correlation between several Basque sections and Bjala indicates that the D–S boundary is located 30
precession cycles (~630 ky) above C27n. In addition to the precession-related marl–limestone couplets and
100-ky eccentricity bundles recognized in the studied sections, expression of the stable 405-ky long
eccentricity allows direct tuning to the astronomical solutions. A correlation of the land-based sections with
previously tuned data from ODP Site1262 from the Southern Atlantic is challenged. Our choice is consistent
with original tuning at Zumaia but shifts one 100-ky cycle older previous tuning from Site 1262 along the
interval above C27n. Under the preferred tuning scheme the D–S boundary can be given an age of 61.641±
0.040 Ma on the La04 orbital solution.
Description:
Published
Description:
511-533
Description:
2.2. Laboratorio di paleomagnetismo
Description:
JCR Journal
Description:
restricted
Keywords:
Paleocene
;
Magnetostratigraphy
;
Orbital tuning
;
Calcareous nannofossils
;
Selandian GSSP
;
04. Solid Earth::04.04. Geology::04.04.08. Sediments: dating, processes, transport
;
04. Solid Earth::04.04. Geology::04.04.10. Stratigraphy
;
04. Solid Earth::04.05. Geomagnetism::04.05.06. Paleomagnetism
Repository Name:
Istituto Nazionale di Geofisica e Vulcanologia (INGV)
Type:
article
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