Basalt flood

Sharma, M., Basu, A.R., Nesterenko, G.V. 1992. Temporal, Sr-, Nd- and Pb-isotopic variations in the Siberian flood basalts implications for the plume-source characteristics. Earth and Planetary. Science Letters, 113, 365-381. 

A gross subdivision of the Moon s surface is based on albedo. The bright regions are the highlands, which are clearly ancient because of their high densities of impact craters. The dark regions are younger maria, basaltic lavas that flooded the impact basins on the nearside of the Moon. Mare basalts are exposed over 17% of the lunar surface and probably comprise only 1% of the crustal volume. 

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. 

These basalts represent the oceanic subclass of so-called intraplate basalts, which also include continental varieties of flood and rift basalts. They will be collectively referred to as OIE, even though many of them are not found on actual oceanic islands either because they never rose above sea level or because they were formed on islands that have sunk below sea level. Continental and island arc basalts will not be discussed here, because at least some of them have clearly been contaminated by continental crust. Others may or may not originate in, or have been contaminated by, the subcontinental lithosphere. For this reason, they are not considered in the present chapter, which is concerned primarily with the chemistry of the sublitho-spheric mantle. 

Campbell I. H. and Griffiths R. W. (1990) Implications of mantle plume structure for the evolution of flood basalts. Earth Planet. Sci. Utt. 99, 79-93. 

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. 

Basu A. R., Renne P. R., Dasgupta D. K., Teichmann F., and Poreda R. J. (1993) Early and late alkah igneous pulses and a high He plume origin for the Deccan flood basalts. Science 261, 902-906. 

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...

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