Paper No. 13
Presentation Time: 9:00 AM-6:00 PM


MATSUNAGA, Aya1, CLARK, Nichole1, BROOKS, Gregg2 and LARSON, Bekka2, (1)Dept. of Marine Science, Eckerd College, St. Petersburg, FL 33711, (2)Dept. of Marine Science, Eckerd College, St. Petersburg, FL 33705,

228Th, part of the 232Th decay series, is delivered to marine systems primarily by rivers and in situ production, and has been shown to have a strong particle affinity, which should make it an ideal geochronological tool. It has not received wide use as a geochronological tool, however, primarily due to the short half-life (~1.91 years), which is too short for most depositional systems.

210Pb and 234Th analyses have shown that surficial Gulf of Mexico sediments following the 2010 BP blowout event accumulated at extremely rapid rates, up to 100x greater than rates of underlying, “natural” sediments. Since over two years has passed since the BP event, the time frame is now ideal for investigating the utility of 228Th as a geochronological tool.

Using gamma spectroscopy, 212Pb and 208Tl are used as proxies for 228Th, and are detected to depths of 5-6 cm in cores collected almost 2 years following the event. Down-core 228Th profiles are consistent with decay profiles and support 210Pb and 234Th data indicating extremely rapid sediment accumulation following the 2010 BP blowout event.

While work is still in progress, 228Th appears to be a promising tool for bridging the gap between 210Pb (half-life ~22.3 years) and 234Th (half-life ~24 days) geochronometers, thereby allowing for the investigation of sedimentary processes over a range of time scales.