GSSP for Northgrippian Stage
Definition:
The base of the Northgrippian Stage (Middle Holocene
Subseries/Subepoch) of
the Holocene Series/Epoch is defined in the NGRIP1 ice-core record at a
depth of
1228.67 m at a horizon which shows a clear signal of climatic cooling
following a
period of generally rising temperatures during the Early Holocene.
It corresponds to an age of 8236 years b2k (before AD2000).
Location:
The Northgrippian GSSP is located in the borehole NGRIP1 in the central Greenland
ice sheet
at a latitude of 75.10°N and a longitude of 42.32°W.
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Sedimentology:
The NGRIP1 ice core consists almost entirely of glacier ice.
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Primary Markers:
The base of the Northgrippian Stage of the Holocene Series/Epoch is
defined by a
shift in the oxygen isotope record to low 18O/16O
and
D/H values.
Secondary Markers:
The GSSP is placed in the middle of a double peak in electrical
conductivity
measurements that marks a volcanic eruption, probably in Iceland. This
double
peak likely relates to a single eruption, as sulfuric acid often
arrives in Greenland in
peaks, with several subpeaks 1- 2 years after the eruption. While it
has not been
linked to a specific eruption, the layer is found in all deep Greenland
ice cores.
Correlation Events:
Climatic cooling following a period of generally rising temperatures
during the
Early Holocene
Other Locations around the World:
A global auxiliary stratotype (latitude of 13°13’S, longitude of
44°03’W)
is placed
at 293 - 287 mm level of Speleothem PAD07 (Stalagmite), Gruta do Padre
Cave,
Brazil at a marked shift of δ18O levels to lighter
isotopic values.
References:
Walker, M., Head, M.J., Berkelhammer, M., Björck, S., Cheng, H., Cwynar, L., Fisher, D.,
Gkinis,
V., Long, A., Lowe, j., Newnham, R., Rasmussen, S.O., Weiss, H., 2018. Formal ratification of
the subdivision of the Holocene Series/ Epoch (Quaternary System/Period): two new Global
Boundary Stratotype Sections and Points (GSSPs) and three new stages/ subseries. Episodes
41/4, 1-11.
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