Eastern Equatorial Pacific Deglacial Atmospheric Dust Flux Data ----------------------------------------------------------------------- World Data Center for Paleoclimatology, Boulder and NOAA Paleoclimatology Program ----------------------------------------------------------------------- NOTE: PLEASE CITE CONTRIBUTORS WHEN USING THIS DATA!!!!! NAME OF DATA SET: Eastern Equatorial Pacific Deglacial Atmospheric Dust Flux Data LAST UPDATE: 6/2007 (Original receipt by WDC Paleo) CONTRIBUTOR: Franco Marcantonio, Texas A&M University IGBP PAGES/WDCA CONTRIBUTION SERIES NUMBER: 2007-055 SUGGESTED DATA CITATION: McGee, D., et al. 2007. Eastern Equatorial Pacific Deglacial Atmospheric Dust Flux Data. IGBP PAGES/World Data Center for Paleoclimatology Data Contribution Series # 2007-055. NOAA/NCDC Paleoclimatology Program, Boulder CO, USA. ORIGINAL REFERENCE: McGee, D., F. Marcantonio, and J. Lynch-Stieglitz. 2007. Deglacial changes in dust flux in the eastern equatorial Pacific. Earth and Planetary Science Letters, Vol. 257, Issues 1-2, pp. 215-230, 15 May 2007. doi:10.1016/j.epsl.2007.02.033 ABSTRACT: Atmospheric dust levels may play important roles in feedbacks linking continental source areas, tropical convection, marine productivity, and global climate. These feedbacks appear to be particularly significant in the tropical Pacific, where variations in local convection and productivity have been demonstrated to have impacts on climate at higher latitudes. Modeling of past dust levels and related feedbacks has been limited, however, by a paucity of observational data. In this study we present a temporal and spatial survey of dust fluxes to the eastern equatorial Pacific over the past 30 kyr. Glacial and Holocene fluxes of 232Th, a proxy for continental material, were calculated by normalization to 230Th from a north-south transect of cores along 110°W between 3°S and 7°N (ODP sites 848-853). Fluxes were 30–100% higher during the last glacial, suggesting increased dustiness in both hemispheres during the glacial period. In both time periods, dust fluxes decrease towards the south, reflecting scavenging of Northern Hemisphere dust by precipitation at the ITCZ. The Holocene meridional dust flux gradient between 7°N and 3°S is characterized by a steep drop in dust levels at the southern edge of the modern range of the ITCZ, while the gradient is shallower and more nearly linear during the last glacial. This change may indicate that the glacial ITCZ in this region was a less effective barrier to interhemispheric dust transport, most likely due to a decrease in convective intensity and precipitation during the last glacial; alternatively, the change in gradient may be explained by increased variability in the location of the glacial ITCZ. Our data do not appear to require a mean southerly displacement of the glacial ITCZ, as suggested by the results of other studies. GEOGRAPHIC REGION: Eastern Equatorial Pacific PERIOD OF RECORD: 30 KYrBP - present FUNDING SOURCES: US National Science Foundation grant OCE-0402311 and Graduate Research Fellowship Program. DESCRIPTION: Glacial and Holocene fluxes of 232Th, a proxy for continental material, from 6 Ocean Drilling Program Cores in the eastern equatorial Pacific. The sites form a north-south transect along 110°W between 3°S and 7°N. Site Locations, ODP Leg 138: 848B 2.99°S 110.48°W water depth 3853 m 849A 0.18°N 110.52°W water depth 3837 m 850A 1.30°N 110.52°W water depth 3786 m 851E 2.77°N 110.57°W water depth 3760 m 852A 5.29°N 110.08°W water depth 3860 m 853B 7.21°N 109.76°W water depth 3714 m Stable isotope values are from G. sacculifer. Oxygen isotope precision is better than 0.08 per mil External reproducibility on Th and U concentrations, based on replicate analyses, is less than 2%. DATA: Leg,Core,Sect, Depth mbsf d18O d13C 232Th(ng/g) 230Th(ng/g) 238U(ng/g) Interval (cm.) 138-848B-1H-1 0-2 0.00 -0.81 1.27 174.61 0.276 203.92 10-12 0.10 -1.30 1.66 164.57 0.256 215.46 20-22 0.20 -0.26 2.13 189.88 0.227 248.99 30-32 0.30 -0.14 1.72 258.63 0.230 261.56 40-42 0.40 -0.38 1.59 351.80 0.257 205.45 50-52 0.50 0.18 1.77 359.48 0.253 183.41 60-62 0.60 -0.21 1.34 300.40 0.231 172.59 138-849A-1H-1 0-2 0.00 -0.87 1.06 202.33 0.276 313.97 10-12 0.10 -0.83 1.99 156.78 0.223 355.53 20-22 0.20 -0.75 1.48 146.07 0.183 278.26 30-32 0.30 -0.48 1.76 154.43 0.163 275.64 40-42 0.40 -0.26 1.45 243.15 0.191 267.46 50-52 0.50 0.07 1.62 281.20 0.193 254.81 60-62 0.60 0.25 1.52 375.95 0.215 207.05 70-72 0.70 0.01 1.74 348.75 0.202 186.51 80-82 0.80 -0.10 1.44 349.38 0.182 191.78 90-92 0.90 -0.41 1.78 301.35 0.167 190.05 138-850A-1H-1 0-2 0.00 -0.64 1.08 246.23 0.298 273.01 10-12 0.10 -1.36 1.81 174.52 0.201 208.57 20-22 0.20 -1.22 1.98 175.07 0.187 218.45 30-32 0.30 -0.46 1.82 314.72 0.197 288.14 40-42 0.40 -0.20 1.49 382.86 0.206 196.64 50-52 0.50 -0.39 1.81 347.84 0.170 137.72 60-62 0.60 -0.59 1.73 400.86 0.193 160.75 138-851E-1H-1 0-2 0.00 -1.30 1.49 222.26 0.205 187.43 10-12 0.10 -1.27 1.7 262.56 0.257 221.73 20-22 0.20 -1.29 1.83 260.59 0.224 230.08 30-32 0.30 -0.63 1.71 409.13 0.212 379.89 40-42 0.40 -0.36 1.47 388.95 0.186 234.07 50-52 0.50 -0.47 1.8 275.90 0.127 120.99 60-62 0.60 -0.55 1.7 355.44 0.155 147.54 138-852A-1H-1 0-2 0.00 -1.44 1.77 593.64 0.343 286.69 5-7 0.05 -1.05 1.8 808.80 0.470 397.17 10-12 0.10 -1.29 1.82 602.70 0.300 281.91 15-17 0.15 -0.85 1.92 956.68 0.397 417.09 20-22 0.20 -0.74 1.8 1021.83 0.400 399.25 25-27 0.25 -0.34 1.61 868.89 0.349 313.35 30-35 0.30 -0.57 1.67 593.14 0.232 218.03 35-37 0.35 -0.65 2.1 558.05 0.221 219.10 40-42 0.40 -0.58 1.83 627.78 0.246 236.51 138-853B-1H-1 0-2 0.00 -1.10 1.43 1177.11 0.551 426.00 3-5 0.03 -1.10 1.59 1236.90 0.513 423.09 6-8 0.06 -0.88 1.58 1389.62 0.532 479.87 9-11 0.09 ND ND 1010.58 0.375 339.34 12-14 0.12 -0.61 1.8 1460.87 0.504 430.72 15-17 0.15 -0.55 1.91 1045.01 0.344 317.68 18-20 0.18 -0.87 2.13 891.86 0.263 289.44