(Appendix 1) Element concentrations in sediment and basalt samples from DSDP Holes 75-530A and 75-530B

The REE patterns of OSAB suggest a basaltic origin. The possible sources are Kaoko basalt in Southwest Africa or Namibia and the basaltic Walvis Ridge itself. The decrease in the area covered by Kaoko basalt due to erosion, the subsidence of the Walvis Ridge, and the improvement of water circulation led to changes in the Eu anomaly from Campanian to Paleocene, and resulted in the YSAB REE pattern.

Changes in the Sm/Eu, La/Th, Th/Yb, Ti/Al2O3, FeO/Al2O3, and Hf/Al2O3 ratios suggest changes of average source rock composition from and esite to granodiorite.The REE abundances and patterns of younger sediments in the Angola Basin (YSAB) are very similar to those observed in NASC, PAAS, and ES sediments. The YSAB REE abundances and patterns may represent the average REE distribution of the exposed African continental crust.

The strong resemblance of REE distributions of YSAB, NASC, PAAS and ES suggests thorough REE mixing from different sources and the uniformity of the average crustal compositions of different continents: Africa, North America, Australia, and Europe.