Lower crust mafic

Blundy JD, Brooker RA (2003) Trace element partitioning during melting and ciystalhzation of mafic rocks in the lower crust. Contrib Mineral Petrol (submitted). 

Constantin M., Hekinian R., Ackermand D., and Staffers P. (1995) Mafic and ultramafic intrusions into upper mantle peridotites from fast spreading centers of the Easter microsplate (South East Pacific). In Mantle and Lower Crust Exposed in Oceanic Ridges and in Ophiolites (eds. R. L. M. Vissers and A. Nicolas). Kluwer Academic, Dordrecht, Boston, London, pp. 71-120. 

Of all the estimates in Table 9, that of Taylor and McLennan (1985, 1995) stands out as being the most mahc overall (Figures 15 and 16). This mahc composition stems from their model for Archean crust, which constimtes 75% of their crust and is composed of a 2 1 mixture of mafic-to felsic-igneous rocks. This relatively mafic crust composition was necessitated by their inferred low heat production in Archean crust and the inferred large proportion of the Archean-aged crust. However, such a high proportion of mafic rocks in the Archean crust is at odds with seismic data (summarized in Section 3.01.3), which show that the crust of most Archean cratons is dominated by low velocities, implying the presence of felsic (not mafic) compositions, even in the lower crust. In addition, some of the... 

Davis W. J. (1997) U—Pb zircon and rutile ages from granuhte xenoliths in the Slave province evidence for mafic magmatism in the lower crust coincident with Proterozoic dike swarms. Geology 25(4), 343—346. 

Lee C.-Y., Chung S. L., Chen C.-H., and Hsieh Y. L. (1993) Mafic granulite xenoliths from Penghu Islands evidence for basic lower crust in SE China continental margin. J. Geol. Soc. China 351-379. 

Shatsky V., Rudnick R. L., and Jagoutz E. (1990) Mafic granulites from Udachnaya pipe, Yakutia samples of Archean lower crust Deep Seated Magmatism and Evolution of Lithosphere of the Siberian Platform, 23 - 24. 

Petford N. and Gallagher K. (2001) Partial melting of mafic (amphibolitic) lower crust by periodic influx of basaltic magma. Earth Planet. Sci. Lett. 193, 483-499. 

Cascades, Washington generation of calc-alkaline granitoids by melting of mafic lower crust with variable water fugacity. Contrib. Mineral. Petrol. 113, 333-351. 

This section is based on a limited compilation of plutonic rock compositions from intermediate, calc-alkaline bathohths, such as are common among Mesozoic and early Tertiary exposures associated with circum-Pacrfic arcs. Section 3.18.4 describes the composition of plutonic rocks from exposed arc sections that extend into the lower crust, including a much larger proportion of mafic gabbros. 

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