Chen, Tian-Yu, Ling, Hong-Fei, Hu, Rong, Frank, Martin and Jiang, Shao-Yong (2013) Lead isotope provinciality of central North Pacific Deep Water over the Cenozoic. Geochemistry, Geophysics, Geosystems, 14 (5). pp. 1523-1537. DOI 10.1002/ggge.20114.

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Abstract

Understanding the pre-anthropogenic Pb cycle of central North Pacific deep water has attracted a lot of
attention in recent years, partly because of its unique geographical location in that it is a remote gyre system
characterized by high dust fluxes and sluggish overturning circulation. However, the factors controlling Pb
isotope evolution in this area over the Cenozoic are still controversial and various mechanisms have been
proposed in previous studies. Here we report new Pb and Nd isotope time series of four ferromanganese
crusts (two from the western Pacific near the Mariana arc and the other two from the central Pacific).
Together with previously published records, we discuss for the first time the significance of a persistent
and systematic Pb isotopic provinciality recorded by central North Pacific crusts over the Cenozoic. We
propose that globally well mixed stratosphere volcanic aerosols could contribute Pb but have not been
the major factors controlling the Pb isotope distribution in the central North Pacific over time. Island arc
input (and probably enhanced hydrothermal input between about 45 and 20 Ma) likely controlled the Pb
isotope provinciality and evolution prior to ~20 Ma, when coeval Pb isotope records in different crusts
showed large differences and atmospheric silicate dust flux was extremely low. After the Eocene, in particular
after 20 Ma, Asian dust input has become an isotopically resolvable source, while island arc-derived Pb
has remained important to balance the dust input and to produce the observed Pb isotope distribution in the
central North Pacific during this period.

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