Evidence for at least two different sources of Asian dust to the Northwest Pacific ocean since the Eocene

Author(s): Scudder, R.; Murray, Rick W.; Zheng, H.; Tada, Ryuji
Author Affiliation(s): Primary:
Boston University, Boston, MA, United States
Other:
Nanjing Normal University, China
University of Tokyo, Japan
Volume Title: AGU 2014 fall meeting
Source: American Geophysical Union Fall Meeting, Vol.2014; American Geophysical Union 2014 fall meeting, San Francisco, CA, Dec. 15-19, 2014. Publisher: American Geophysical Union, Washington, DC, United States
Note: In English
Summary: Atmospheric dust records in ice cores and marine sediment provide important information regarding global climate, tectonics, and ocean-atmospheric interactions over many different timescales. In particular, marine records from the northwest Pacific are of critical importance to our understanding of the development of the Asian Monsoon, the onset of Northern Hemisphere Glaciation, and other important climatic features. Changes in dust sources have been documented over short timescales related to monsoonal dynamics; however, studies over much longer timescales commonly consider canonical "Chinese Loess" as the sole source of Asian dust. Here we present a new marine record from Ocean Drilling Program Site 1149 that indicates the clear presence of at least two different sources of Asian dust over the past 60 Ma. Using a multi-elemental geochemical and statistical approach we have resolved two disparate eolian dust inputs to Site 1149, in addition to two different ash sources. The first dust source appears to be Chinese Loess (CL); whereas, the second dust source is compositionally distinct from CL and is similar in composition to general Upper Continental Crust. These two sources show contrasting accumulation patterns through the Cenozoic. Our results confirm previous studies that show the CL source increasing in importance over the past 8 Ma. Further, our data show that the second eolian input from Asia decreases in importance from 60 Ma to ∼22 Ma. This second dust source shows variability throughout the Cenozoic that can be related to major climatic events and terrestrial climate records from China, yet ceases to be important younger than ∼22 Ma. The time period from ∼25-20 Ma, therefore, appears to represent a fundamental transition in the hydrologic behavior of the Asian interior. That there are two important dust sources through the Cenozoic, rather than just the single "Chinese Loess", offers new opportunities for inferring the climate and tectonic evolution of Asia and the northern hemisphere.
Year of Publication: 2014
Research Program: ODP Ocean Drilling Program
Key Words: 12 Stratigraphy, Historical Geology and Paleoecology; Clastic sediments; Dust; Leg 185; Marine sediments; North Pacific; Northwest Pacific; ODP Site 1149; Ocean Drilling Program; Pacific Ocean; Sediments; West Pacific
Coordinates: N312030 N312030 E1432100 E1432100
Record ID: 2015114652
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