Lithium isotopic systematics of granites and pegmatites from the Black Hills, South Dakota

2006/10/01 by Fang‐Zhen Teng, F.-Z. Teng, W. F. McDonough +5 · 5 citations
Earth and Planetary Sciences · #Geology and Paleoclimatology Research #Geological and Geochemical Analysis #earthquake and tectonic studies

paper · doi:10.2138/am.2006.2083

Abstract

To study Li isotopic fractionation during granite differentiation and late-stage pegmatite evolution, Li isotopic compositions and concentrations have been measured for the S-type Harney Peak Granite, the spatially associated Tin Mountain pegmatite, and possible metasedimentary source rocks in the Black Hills, South Dakota. The Harney Peak Granite is isotopically heterogeneous, with δ7Li varying from -3.1 to +6.6. The δ7Li values of Proterozoic metasedimentary rocks that are possible sources of the Harney Peak Granite range from -3.1 to +2.5 and overlap with post- Archean shales and the Harney Peak Granite. For the granite suite, there is no correlation between δ7Li and elements indicative of degrees of granite differentiation (SiO2, Li, Rb, etc.). The Li isotopic composition of the Harney Peak Granite, therefore, appears to reflect the source composition.

Citations

• An experimental study of element partitioning among biotite, muscovite, and coexisting peraluminous silicic melt at 200 MPa (H 2 O)

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