Abstract. A consistent chronostratigraphic framework is required to understand the
effect of major paleoclimate perturbations on both marine and terrestrial
ecosystems. Transient global warming events in the early Eocene, at 56–54 Ma, show the impact of large-scale carbon input into the ocean–atmosphere
system. Here we provide the first timescale synchronization of continental
and marine deposits spanning the Paleocene–Eocene Thermal Maximum (PETM) and
the interval just prior to the Eocene Thermal Maximum 2 (ETM-2). Cyclic
variations in geochemical data come from continental drill cores of the
Bighorn Basin Coring Project (BBCP, Wyoming, USA) and from marine deep-sea
drilling deposits retrieved by the Ocean Drilling Program (ODP). Both are
dominated by eccentricity-modulated precession cycles used to construct a
common cyclostratigraphic framework. Integration of age models results in a
revised astrochronology for the PETM in deep-sea records that is now
generally consistent with independent 3He age models. The duration of
the PETM is estimated at ∼ 200 kyr for the carbon isotope excursion and ∼ 120 kyr
for the associated pelagic clay layer. A common terrestrial and marine age
model shows a concurrent major change in marine and terrestrial biota
∼ 200 kyr before ETM-2. In the Bighorn Basin, the change is referred
to as Biohorizon B and represents a period of significant mammalian turnover
and immigration, separating the upper Haplomylus–Ectocion Range Zone
from the Bunophorus Interval Zone and approximating the Wa-4–Wa-5
land mammal zone boundary. In sediments from ODP Site 1262 (Walvis Ridge),
major changes in the biota at this time are documented by the radiation of a
“second generation” of apical spine-bearing sphenolith species (e.g.,
S. radians and S. editus), the emergence of T. orthostylus, and the marked decline of D. multiradiatus.
