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A late Pleistocene–Mid‐Holocene noble gas and stable isotope climate and subglacial record in southern Michigan
Author(s) -
Castro Maria Clara,
Warrier Rohit B.,
Hall Chris M.,
Lohmann Kyger C.
Publication year - 2012
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2012gl053098
Subject(s) - meltwater , younger dryas , geology , holocene , pleistocene , glacial period , ice sheet , paleoclimatology , ice core , oceanography , climate change , physical geography , climatology , paleontology , geography
Stable isotopes ( δ D, δ 18 O) and 14 C derived ages in the Saginaw aquifer in southern Michigan suggest subglacial meltwater contributions from the Laurentide Ice Sheet of up to 36% in the late Pleistocene, following the Last Glacial Maximum. Contributions of up to 74% from previous glaciation periods are observed. Together with the Marshall record [ Ma et al. , 2004], noble gas temperatures (NGTs) and excess air (EA) from the Saginaw aquifer capture, for the first time, the onset of the Younger Dryas (∼12.9 kyr BP) with a ∼3.3°C cooling accompanied by drier conditions. Mid‐Holocene (MH) climatic shifts are also identified, with warming (∼2.9°C), increased aridity starting at ∼5.4 kyr BP followed by reversal to cooler, humid conditions at ∼4.1 kyr BP. Except for the last MH reversal, the stable isotope record mimics the NGT and EA records. Contrasting trends displayed by δ 18 O and deuterium‐excess in the last MH reversal suggests enhanced vapor transport from the Gulf of Mexico.