The Etendeka Igneous Province: magma types and their stratigraphic distribution with implications for the evolution of the Parana-Etendeka flood basalt province

Detailed geochemical and field data for the volcanic sequence and intrusion s of the Etendeka Igneous Province are used to construct a stratigraphic fr amework for petrogenetic interpretation of the evolution of the Etendeka-Pa rana continental flood volcanic event. Geochemical and petrographic charact erization of over 1,000 analyzed samples allows 8 mafic and 17 silicic magm a types to be recognized. Both silicic and mafic types can be grouped into high-Ti and low-Ti suites on the basis of elevated Ti relative to other ele ments. The mafic magmas are: Khumib (high-Ti), Tafelberg, Kuidas, Horingbaa i, Huab, Tafelkop, Albin, and Esmeralda (all low-Ti). Amongst the silicic t ypes, the Goboboseb, Springbok, Wereldsend, Grootberg, and Beacon low-Ti qu artz latites, and the Nil Desperandum high-Ti latite have been described pr eviously. In addition, the Hoas (low-Ti), Nadas, Sechomib, and Hoarusib, (a ll high-Ti) latites and the Fria (low-Ti), Sarusas, Ventura, Khoraseb, Naud e, and Elliott (all high-Ti) quartz latites are described for the first tim e here. There is a marked provinciality in the distribution of the high- an d low-Ti suites, with the former concentrated in the Northern Etendeka regi on and the latter dominant in the Southern Etendeka. Stratigraphic distribu tion of magma types allows two new formations to be defined in the Northern Etendeka - the Khumib Formation of basaltic flows and the Skeleton Coast F ormation dominated by silicic sheets. The geochemical provinciality hampers precise correlations between Northern and Southern Etendeka. Available evi dence suggests that the lower part of the Awahab Formation in the Southern Etendeka is coeval with the lower part of the Khumib Formation and that the silicic units in the upper part of the Tafelberg Formation probably correl ate with the Skeleton Coast Formation. The paucity of Khumib dykes in relat ion to Tafelberg dykes and their field relationships with regard to the vol canic sequence in the Northern Etendeka suggests that the main Khumib erupt ive centers lay further north, consistent with southward thinning of the Kh umib basalts. In the Southern Etendeka, the Doros complex is the eruptive c enter of the plume-derived Tafelkop basalts, which probably built a shield volcano within the regional flood lava field. This work indicates that the Etendeka has a greater variety of both silicic and low-Ti mafic magma types than are known from the SE Parana. Detailed comparisons reveal that all th e important silicic types in the Parana have geochemical equivalents in the Etendeka. New correlations are Santa Maria=Fria, Ourinhos=Khoraseb, Guarap uava=Sarusas, thus extending the previously recognized correlations between Southern Etendeka quartz latites and the Caixas do Sul and Anita Garibaldi "rhyolites." These correlations emphasize that very large volume silicic s ystems develop with pronounced lithospheric rifting in continental flood ba salt provinces.