Meltwater pulse 1B

Meltwater pulse 1B (MWP1b) is the name used by Quaternary geologists, paleoclimatologists, and oceanographers for a period of either rapid or just accelerated post-glacial sea level rise that some hypothesize to have occurred between 11,500 and 11,200 years ago at the beginning of the Holocene and after the end of the Younger Dryas.

[6] In 2004, Liu and Milliman reexamined the original data from Barbados and Tahiti and reconsidered the mechanics and sedimentology of reef drowning by sea level rise.

[9][10] In addition, Leventer and others argue that the timing of deglaciation in eastern Antarctica roughly coincides with the onset of meltwater pulse 1B and the Antarctic Ice Sheet is a likely source.

[13] For example, recent research in West Antarctica found that sufficient deglaciation contemporaneous with meltwater pulse 1B occurred to readily explain this rapid period of global sea level rise.

[14] A variety of paleoclimate and paleohydrologic proxies, which can be used to reconstruct the prehistoric discharge of the Mississippi River, can be found in the sediments of the Louisiana continental shelf and slope, including the Orca and Pygmy basins, within the Gulf of Mexico.

[15][16] These proxies have been used by Quaternary geologists, paleoclimatologists, and oceanographers to reconstruct both the duration and discharge the mouth of the prehistoric Mississippi River for the Late glacial and postglacial periods, including the time of meltwater pulse 1B.

The same research found an absence of either meltwater floods or superfloods discharging into the Gulf of Mexico from the Mississippi River during the preceding thousand years, which is known as the cessation event, that corresponds with the Younger Dryas stadial.

The composition of the sediments brought into the Gulf of Mexico and deposited on the Louisiana continental shelf and slope during the superfloods of MWF-5 reflect an abrupt change in mineralogy, fossil content, organic matter, and amount after 12,900 years ago at the start of the Younger Dryas interval.

Second, after 12,900 years ago, the overall quantity of sediment being transported down the Mississippi River abruptly decreases with a corresponding and significantly increased proportion of locally produced biologically generated carbonate and organic matter.

[21][22] The above noted changes in the nature of accumulating sediments indicate that after the start of the Younger Dryas, the southern route for Laurentide Ice Sheet meltwater was largely blocked.

Research by Weber and others constructed a record from variations in the amount of iceberg-rafted debris versus time and other environmental proxies in two cores taken from the ocean bottom within Iceberg Alley of the Weddell Sea.