Continental flood-basalts

Anderson D. L. (1994) The sublithospheric mantle as the source of continental flood basalts the case against the continental lithosphere and plume head reservoirs. Earth Planet. Set Lett. 123, 269-280. 

Menzies M. A. (1992) The lower hthosphere as a major source for continental flood basalts a re-appraisal. In Magmatism and the Causes of Continental Break-up, Geol. Soc. Spec. Publ. (eds. B. C. Storey, T. Alabaster, and R. J. Pankhurst). The Geological Society, London, vol. 68, pp. 31 -40. 

Thompson R. N., Morrison M. A., Hendry G. L., and Parry S. L. (1983) Continental flood basalts...arachnids rule OK In Continental Flood Basalts and Mantle Xenoliths (eds. C. J. Hawkesworth and M. J. Norry). Shiva, Nantwich, pp. 158-185. 

Figure 5 Average Ce/Pb and Nb/U from selected kimberlites, continental alkali basalts, and continental flood basalts. Present-day continental crust values from Condie (1993), and MORE and OIB values from Hofmann (1997)...

Figure 6 Major element compositions of alkali basalts and continental flood basalts (a) total alkali elements versus wt.% Si02- Dashed line separating alkaline from subalkaline (tholeiitic) basalts from Irvine and Baragar (1971) and (b) wt.% Ti02 versus wt.% MgO. Data from Tables 2 and 3.

The problem of crustal contamination is particularly acute for low mg continental flood basalts and smaller volume continental tholeiitic basalts, both of which have low trace-element concentrations (see Sections 3.03.3.2.3 and 3.03.3.3). The issue is less critical for many smaller volume continental rocks, such as kimberlites and alkali basalts, which have much higher abundances of many trace elements. As a result of their high strontium and neodymium content, for example, the isotopic compositions of these elements in kimberlites and alkali basalts are relatively insensitive to modification during crustal contamination. Conversely, the osmium and lead concentration of basaltic magmas are so low that these isotope systems are particularly vulnerable to modification by interaction with cmstal rocks (McBride et al, 2001 Chesley et al, 2002) hence these systems provide relatively sensitive indicators of crustal assimilation. 

Figure 14 Locations of selected major Phanerozoic continental flood basalts worldwide. References as in Table 3, with exception of Madgascar (Storey et al., 1997), Emeishan (Chung and Jahn, 1995 Zhou et al, 2002), North Atlantic Igneous Province (Saunders et al, 1997), Ethiopian and Yemeni traps (Menzies et al, 1997 Pik et al, 1999), and Central Atlantic magmatic province (CAMP) (Hames et al, 2000). The separation of CEB provinces into high Ti/Y ( P or plume type) and low Ti/Y ( A or arc type) from Puffer (2001). However, most provinces include examples of both types of basaltic rocks (cf. the Parana-Etendeka provinces). A more complete compilation of terrestrial large igneous provinces can be found...

Table 3 Major element, trace element, and isotopic compositions of continental flood basalts. 

Figure 15 Primitive mantle normalized trace-element abundance for continental flood basalts (data from Table 3).

Figure 16 Initial enci versus Sr/ Sr for continental flood basalts. EA = European asthenospheric reservoir...

Gallagher K. and Hawkesworth C. (1992) Dehydration melting and the generation of continental flood basalts. Nature 258, 57-59. 

Gibson S. A., Thompson R. N., Leonardos O. H., Dickin A. P., and Mitchell J. G. (1999) The limited extent of plume-lithosphere interactions during continental flood-basalt genesis geochemical evidence from Cretaceous magmatism in southern Brazil. Contrib. Mineral. Petrol. 137, 147-169. 

Mahoney J. J. (1988) Deccan Traps. In Continental Flood Basalts (ed. J. D. Macdougall). Kluwer Academic, Dordrecht, 341pp. 

Puffer J. H. (2001) Contrasting high field strength element contents of continental flood basalts from plume versus reactivated-arc sources. Geology 29, 675-678. 

Figure 3 Schematic diagram showing how original lithospheric thickness and mantle potential temperature affect the amount of melt produced (melt thickness) and how these factors relate to continental flood basalts (CFB), volcanic rifted margins (VRM), off-ridge and ridge-centered oceanic plateaus (OP), and midocean ridges (MOR).

Continental flood basalts are not easy to preserve for long periods of time in the geological... 

Although the potential environmental impact of continental flood basalt provinces has been... 

CourtiUot V., Jaeger 1.1., Yang Z. Z., Feraud G., and Hofmann C. K. B. (1996) The influence of continental flood basalts on mass extinctions where do we stand In The Cretaceous-Tertiary Event and Other Catastrophes in Earth History, Geological Society of America Special Paper 307 (eds. G. Ryder, D. Fastovsky, and S. Gartner), pp. 513-525. 

Marzoli A., Renne P. R., Piccirillo E. M., Ernesto M., BeUieni G., and De Min A. (1999) Extensive 200-miUion-year-old continental flood basalts of the Central Atlantic Magmatic Province. Science 284, 616-618. 

To evaluate these questions further, we have looked again at the variations in Pb/ Pb ratios (and thus pi) of Archaean basalts and granitoids worldwide in the age range 3.7-3.8, 3.5, 3.2, 2.9 to 2.7-2.6 Ga. We show that there are provinces with different Pb/ Pb and pj values, and note that some unexpectedly coincide with Mezosoic continental flood basalts and oceanic DUPAL rocks with similar Pb isotope features. 

Wooden, J. L., Czamanske, G. K., Fedorenko, V. A 6 OTHERS 1993. Isotopic and trace element constraints on mantle and crustal contributions to Siberian continental flood basalts, Noril sk area. Geochimica et Cosmochimica Acta, 57, 3677-3704. 

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