walter d. mooney, ph.d. us geological survey menlo park, california usa mooney@usgs

Walter D. Mooney, Ph.D.US Geological SurveyMenlo Park, California USAmooney@usgs.gov

Lecture #7:Challenges and Opportunitiesin Studies of Lithospheric Evolution

CAGS/SinoProbe Short Course: Lithospheric Evolution through Time April 8-12, 2011

Dehydration reactions in subduction zone

Ranero et al., 2004

How much H2O within subducting plate?

[Rüpke et al., 2006]

Faults and Fluid flow

Tveranger et al., 2005

First continental crust

Density differences allow subduction of mafic rocks. Further partial melting and fractionation makes higher silica melt that won’t subduct

Water outKomatiite partially melts, Basalt getsto surface, piles up. The stack sinks, partially melts when pressure high enough. Fractionation makes increasingly silica-rich magmas

First Then:

Generation of Continental Crust through TimeA based on Nd isotopes in shales44 B based on Pb isotopes77 C from Taylor & McLennan (1995)

Hawkesworth & Kemp (2006)

Mantle Structure

Source: Forte and Mitrovica (2001)

Tomographic Model

Van Heijst, Ritsema, and Woodhouse, 1999

Li et al. (in preparation)

Mantle Structure

Modified from: Meibaum and Anderson (2003)

Homogeneous Heterogeneous

Density model of the crust and upper mantle based on joint inversion of the new satellite gravity and seismic data.

M. Kaban, M. Rothacher

Tomographic Model

Van Heijst, Ritsema, and Woodhouse, 1999

Li et al. (in preparation)

Mantle Structure

Modified from: Meibaum and Anderson (2003)

Homogeneous Heterogeneous

Density model of the crust and upper mantle based on joint inversion of the new satellite gravity and seismic data.

M. Kaban, M. Rothacher