229 Recent Advances in Paleoclimatology/Paleoceanography

Wednesday, 3 November 2010
8:00 AM - 12:00 PM
Room 607

BLACK CARBON IN DEEP-SEA SEDIMENTS FROM THE NORTHEASTERN EQUATORIAL PACIFIC OCEAN

Paper number: 229-12
Program: Technical Sessions
Time: 10:45 AM – 11:00 AM

Authors

Abstract

Black carbon (BC) is produced by incomplete combustion of fossil fuels and plant material. Due to its refractory nature, BC in preindustrial sediment can be a tracer of forest fire events. In addition, BC is purely terrestrial in origin, and is transported to marine sediments by atmospheric and fluvial processes. Therefore, distribution of BC in deep-sea sediments, where effect of fluvial processes can be excluded, would be used to understand atmospheric circulation. This study dealt with BC in a 328 cm-long piston core collected from the northeastern equatorial Pacific Ocean (16°12'N, 125°59'W), covering the last 15 Ma (Hyeong at al., 2004). Concentration of BC was varied from 0.000% to 0.185% of total sediments. Mass accumulation rate (MAR) of BC ranged between 0.000 mg/cm²/1000 yrs and 34.675 mg/cm²/1000 yrs. An increase of MAR in sediments younger than 8 Ma (av. 9.5 mg/cm²/1000 yrs) from av. 3.8 mg/cm²/1000 yrs in sediments older than 8 Ma is noted with an extraordinary high value (~35 mg/cm²/1000 yrs) in sediment deposited near 2.1 Ma and 4.4 Ma ago. This change of MAR seems to be related to the meridional migration of Intertropical Convergence Zone (ITCZ) at around 8 Ma in the study area. Accordingly, higher BC content in sediment younger than 8 Ma seems to be accounted for by its derivation from the Northern Hemisphere compared to that from the Southern Hemisphere in older sediment. Two high BC values in sediment near 2.1 Ma and 4.4 Ma may be ascribed to intense Cenozoic volcanic activities in the circum-Pacific region (Kennett at al., 1977).

Hyeong, K., S.-H. Park, C.M. Yoo, and K-H. KIm, 2005, Mineralogical and geochemical compositions of the eolian dust from the northeast equatorial Pacific and their implications on paleolocation of Intertropical Convergence Zone, Paleoceanography, 20, PA1010, doi:10.1029/2004PA001053

Kennett, J.P., McBirney, A.R. and Thunell, R.C., 1977. Episodes of Cenozoic volcanism in the circum-Pacific region. J. Volcanol. Geotherm. Res., 2: 145-163.