Reconstruction of South Pacific dust accumulation during the early Paleogene greenhouse

Online Access: Get full text
Author(s): Amaya, D.; Thomas, D. J.; Marcantonio, F.; Korty, R.; Huber, M.; Winckler, G.; Alvarez Zarikian, C. A.
Author Affiliation(s): Primary:
Texas A&M University, Oceanography, College Station, TX, United States
Purdue University, United States
Lamont-Doherty Earth Observatory, United States
, United States
Volume Title: AGU 2012 fall meeting
Source: American Geophysical Union Fall Meeting, Vol.2012; American Geophysical Union 2012 fall meeting, San Francisco, CA, Dec. 3-7, 2012. Publisher: American Geophysical Union, Washington, DC, United States
Note: In English
Summary: The accumulation of dust in remote, pelagic sediments is controlled by aridity in the source regions as well as the gustiness of the transporting winds. Models and theory predict lower zonal wind intensities and gustiness in climates characterized by diminished meridional gradients such as the Late Cretaceous and early Paleogene. The few published long-term data indicate overall lower dust accumulation in the northern Pacific and southern Indian Ocean during the Late Cretaceous and early Paleogene than during the Neogene, as well as higher dust accumulation in the Northern Hemisphere than that in the south during the Late Cretaceous and early Paleogene. However, the existing dust reconstruction likely is biased by sparse coverage, particularly from the Pacific with data limited to the northern low and subtropical latitudes. To begin examining the South Pacific, we took advantage of an extensive geochemical data set generated for DSDP Site 596, and estimated 232Th-based dust fluxes from the published 232Th concentration data and sediment mass accumulation rates. The long-term trend and absolute flux values from Site 596 are similar to that of the northern Pacific GPC3, with the exception of the late Paleocene-early Eocene and the late Neogene. We also generated a new 232Th-based dust accumulation record from IODP Site U1370 to begin examining the record from southern temperate and high latitudes (Site U1370 backtracks to close to 60°S at 50 Ma). The Site U1370 data reveal dust fluxes significantly higher than those recorded in the North Pacific, however the overall decrease from ∼65 Ma to ∼25 Ma is similar to the trends at Site 576 and GPC3. The new South Pacific data suggests that Sites 596 and U1370 were influenced by different prevailing winds (e.g., delivering dust from source regions with different vegetation/hydrologic conditions), different levels of storminess/gustiness, or a combination of both. If the dust fluxes recorded at Site U1370 are representative of the high latitude South Pacific, then dust supplies and storminess/gustiness in the region were higher than in the subtropics and tropics. The new dust data from Site U1370 are consistent with recent model simulations that predict higher wind intensities in the Southern Hemisphere than in the north during the early Paleogene. These results begin to suggest a significantly different reconstruction of wind gustiness, storminess and source region aridity than assumed over the past few decades.
Year of Publication: 2012
Research Program: DSDP Deep Sea Drilling Project
IODP Integrated Ocean Drilling Program
IPOD International Phase of Ocean Drilling
Key Words: 12 Stratigraphy, Historical Geology and Paleoecology; Cenozoic; Clastic sediments; DSDP Site 576; DSDP Site 596; Deep Sea Drilling Project; Dust; East Pacific; Expedition 329; IODP Site U1370; IPOD; Integrated Ocean Drilling Program; Leg 86; Leg 91; Lower Paleogene; North Pacific; Northwest Pacific; Pacific Ocean; Paleoclimatology; Paleogene; Sediments; South Pacific; Southeast Pacific; Tertiary; West Pacific
Coordinates: N322121 N322122 E1641633 E1641632
S415107 S415107 W1530623 W1530623
S235113 S235111 W1653916 W1653917
Record ID: 2015005567
Copyright Information: GeoRef, Copyright 2019 American Geosciences Institute. Reference includes data supplied by, and/or abstract, Copyright, American Geophysical Union, Washington, DC, United States