Radiocarbon-derived sedimentation rates in the Gulf of Mexico

TitleRadiocarbon-derived sedimentation rates in the Gulf of Mexico
Publication TypeJournal Article
Year of Publication2008
AuthorsSantschi, PH, Rowe, GT
JournalDeep-Sea Research Part Ii-Topical Studies in Oceanography
Date PublishedDec
ISBN Number0967-0645
Keywordsaccumulation, ATCHAFALAYA RIVER, cores, Gulf of Mexico, ice-sheet, Mass, Meltwater, MISSISSIPPI RIVER DELTA, Nepheloid layer transport, Organic carbon burial rates, radiocarbon, Sedimentation rates, TERRIGENOUS ORGANIC-MATTER, wasting

Sedimentation rates were determined for the northern Gulf of Mexico margin sediments at water depths ranging from 770 to 3560m, using radiocarbon determinations of organic matter. Resulting sedimentation rates ranged from 3 to 15 cm/kyr, decreasing with increasing water depth. These rates agree with long-term sedimentation rates estimated previously using stratigraphic methods, and with estimates of sediment delivery rates by the Mississippi River to the northern Gulf of Mexico, but are generally higher by 1-2 orders of magnitude than those estimated by (210)Pb(xs) methods. Near-surface slope sediments from 2737 to water depth in the Mississippi River fan were much older than the rest. They had minimum (14)C ages of 16-27 kyr and delta(13)C values ranging from -24 parts per thousand to -26.59 parts per thousand, indicating a terrestrial origin of organic matter. The sediments from this site were thus likely deposited by episodic mass wasting of slope sediment through the canyon, delineating the previously suggested main pathway of sediment and clay movement to abyssal Gulf sediments. (C) 2008 Published by Elsevier Ltd.