GSSP for Meghalayan Stage
Definition:
The base of the Meghalayan Stage (Upper/Late Holocene
Subseries/Subepoch) of
the Holocene Series/Epoch is defined in the Mawmluh Cave speleothem in
NE India
and dated at 4250yr bk2 (before AD2000).
Location:
The Meghalayan GSSP is located in the northeastern Indian State of Meghalaya. The
entrance
of Mawmluh Cave is at the southern edge of the Meghalayan Plateau at a latitude
of
25°15'44"N and a longitude of 91°42'54"W. The nearest town is Sohra
(Cherrapunji).
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Sedimentology:
Mawmluh Cave is overlain by 30 - 100m of limestone and sandstone and
formed
along the contact between the Lower Eocen Lakadong dolomite and the
Therria
Sandstone.
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Primary Markers:
The GSSP is defined in a speleothem (KM-A) with a modelled age of
4250yr bk2
(before AD2000), where the stable isotope profile shows a shift to
heavier isotopic
values, reflecting an abrupt reduction in precipitation due to
weakening of the
monsoon across the Indian sub-continent and southeast Asia.
Correlation Events:
Stable isotope profile shows a shift to heavier isotopic values,
Other Locations around the World:
This so-called 4.2 ka event is recognized worldwide. Most mid- and low-
latitude
records indicate the abrupt onset of aridification. In northern and
high latitudes
glacier advancements are pronounced, while in Antarctica sea ice cover
and lower
sea surface temperatures start at 4.2ka.
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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