Abstract:
The data consist of oxygen and carbon isotope measurement of carbonate samples
microdrilled from sequential growth increments of 1 specimen of the bivalve
Arctica ovata. The sample was collected by L. Marincovich, Jr., from the
Mount Moore Formation of the Eureka Sound Group on Ellesmere Island, Canada.
At the time of publication (1996), the age of the sample was
... estimated to be Danian.
This sample is Field No. 84LM14.
Abstract
Characterizing polar climates during past warm intervals is important for
understanding "greenhouse" climate dynamics because high-latitude surface
temperatures and precipitation patterns are extremely sensitive to global
climatic conditions. Model-data comparisons of high-latitude climates during
past warm intervals (Cretaceous-Eocene, Pliocene) are currently at odds.
Specifically, simulations of past warm climates produce polar regions
characterized by sub-freezing temperatures and significant seasonality,
whereas limited fossil proxy data indicate higher mean annual temperatures and
low seasonality (i.e. an equable climate). We have constructed a data set to
infer northern hemisphere polar marine temperatures during the late Paleocene.
Seasonal and mean annual temperature and the oxygen isotopic composition of
precipitation are reconstructed for an Arctic coastal setting during the
Thanetian (57-58 Ma) using fossil shell stable isotope profiles. We estimate
that coastal water temperatures varied between 10 and 15 degrees C during the
seasons of growth, presumably spring, summer and fall. These findings support
paleontological evidence, implying Northern Hemisphere polar climates were
seasonally warm during the late Paleocene. In addition, estuarine fossil
oxygen isotope profiles show periodic excursions to low values (as low as -19
per mil VPDB), which indicate seasonal pulses of isotopically-depleted
freshwater. 
