Oceanic plateau accretion

Table 2 shows representative analyses of in situ and accreted portions of Cretaceous oceanic plateaus. Cretaceous oceanic plateaus are predominantly basaltic (<10 wt.% MgO) in composition (Figure 5), although more-MgO-rich lava flows are found in the Caribbean-Colombian oceanic plateau (CCOP). Typically, oceanic plateaus possess generally low levels of compatible elements (i.e., Ni < 300 ppm and Cr < 1,000 ppm see Figure 6). In terms of incompatible trace elements the majority of oceanic plateau lavas and intrusive sheets possess relatively flat rare earth... 

Figure 4 Map to show the main accreted outcrops of the Caribbean-Colombian oceanic plateau along with the locations of DSDP/ODP drill holes which penetrated the thickened crust of the Caribbean plate.

Figure 15 Map showing North American accreted oceanic terranes including the oceanic plateau sequences discussed in the text (after Tardy et al, 2001 Condie, 2001).

Desrochers J. P., Hubert C., Ludden J. N., and Pilote P. (1993) Accretion of Archean Oceanic Plateau fragments in the Abitibi Greenstone Belt, Canada. Geology 21, 451-454. 

Pallister J. S., Budahn J. R., and Murchey B. E. (1989) Pillow basalts of the Angayucham terrane—oceanic plateau and island crust accreted to the Brooks Range. J. Geophys. Res 94, 15901-15923. 

The rationale for this section is summed up by this question If the CCOP or OJP were accreted on to a continental margin and preserved in the geologic record for 1 billion years, what features could we use to identify them as oceanic plateaus This section will review diagnostic geochemical and geological characteristics of oceanic plateaus, and then will show, illustrated by examples, how these criteria can be used to identify plateau sequences in the geological record. Table 3 provides a summary of the diagnostic features of Cretaceous oceanic plateaus and mafic sequences... 

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