Gulf of Mexico Deglacial Stable Isotope Data.
The d18O time series of deglaciation in the Gulf of Mexico were acquired from
paired G. ruber white and N. dutertrei planktonic foraminifer shells from
seven piston cores raised from bathyal depths (401 m to 1112 m) and spaced
over a stretch of 315 km on the Louisiana slope (LOUIS).
North American freshwater runoff records have been used ... to support the case
that climate flickers were caused by shutdowns of the ocean thermohaline
circulation (THC) resulting from reversals of meltwater discharges.
Inconsistencies in the documentation of these meltwater switches, however,
continue to fuel the debate on the cause/s of the oscillatory nature of the
deglacial climate. New oxygen and carbon isotope records from the northern
Gulf of Mexico depict in exceptional detail the succession of meltwater floods
and pauses through the southern routing during the interval 16 to 8.9 ka (14C
years BP; ka, kiloannum). The records underscore the bimodal role played by
the Gulf of Mexico as a destination of meltwater discharges from the receding
Laurentide Ice Sheet. The evidence indicates that the Gulf of Mexico acted as
the principal source of superfloods at 13.4, 12.6, and 11.9 ka that reached
the North Atlantic and contributed significantly to density stratification,
disruption of ocean ventilation, and cold reversals. Gulf of Mexico lapsed
into a relief-valve position in post-Younger Dryas time, when meltwater
discharges were rerouted south at 9.9, 9.7, 9.4, and 9.1 ka, thus temporarily
interrupting North Atlantic-bound freshwater discharges from Lake Agassiz. The
history of meltwater events in the Gulf of Mexico contradicts the model that
meltwater flow via the eastern outlets into the North Atlantic disrupted the
ocean THC, causing cooling, while diversions to the Gulf of Mexico via the
Mississippi River enhanced THC and warming.