Deglacial changes in dust flux in the eastern Equatorial Pacific

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doi: 10.1016/j.epsl.2007.02.033
Author(s): McGee, D.; Marcantonio, F.; Lynch-Stieglitz, J.
Author Affiliation(s): Primary:
Tulane University, Department of Earth and Environmental Sciences, New Orleans, LA, United States
Other:
Georgia Institute of Technology, United States
Volume Title: Earth and Planetary Science Letters
Source: Earth and Planetary Science Letters, 257(1-2), p.215-230. Publisher: Elsevier, Amsterdam, Netherlands. ISSN: 0012-821X CODEN: EPSLA2
Note: In English. 80 refs.; illus., incl. 2 tables, sketch map
Summary: 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 inter-hemispheric 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. Abstract Copyright (2007) Elsevier, B.V.
Year of Publication: 2007
Research Program: ODP Ocean Drilling Program
Key Words: 06 Petrology, Sedimentary; 24 Surficial Geology, Quaternary Geology; Actinides; Biogenic structures; Bioturbation; Cenozoic; Circulation; Clastic sediments; Convection; Deglaciation; Dust; East Pacific; Equatorial Pacific; Intertropical Convergence Zone; Isotope ratios; Isotopes; Last glacial maximum; Leg 138; Marine sediments; Metals; O-18/O-16; ODP Site 848; ODP Site 849; ODP Site 850; ODP Site 851; ODP Site 852; ODP Site 853; Ocean Drilling Program; Oxygen; Pacific Ocean; Paleoclimatology; Quaternary; Radioactive isotopes; Sedimentary structures; Sediments; Stable isotopes; Th-230; Th-232; Thorium; Tropical environment; Wind transport
Coordinates: N071239 N071240 W1094504 W1094506
N051733 N051734 W1100432 W1100435
N024612 N024614 W1103417 W1103419
N011749 N011751 W1103116 W1103118
N001058 N001100 W1103110 W1103111
S025940 S025938 W1102847 W1102849
Record ID: 2008016579
Copyright Information: GeoRef, Copyright 2019 American Geosciences Institute. Reference includes data from CAPCAS, Elsevier Scientific Publishers, Amsterdam, Netherlands