Peralkaline Nephelinite-Natrocarbonatite Relationships at Oldoinyo Lengai, Tanzania

Petrogenesis of Natrocarbonatite at Oldoinyo Lengai, East Africa— Evidence from Fe and U Isotope Variations by Zhenhao Zhou Thesis

A supposed s6vite from Oldoinyo Lengai, Tanzania" result of extreme alteration of alkali carbonatite lava

A calcite-rich block in nephelinitic agglomerate at Oldoinyo Lengai comprises Sr-calcite, apatite, fluorite, a Ba-Mn oxide akin to romanrchite, and a distinctive Mn-Fe spinel. Formerly reported as sC3vite, on textural, mineralogical and stable isotope grounds it is now re-interpreted as a highly-altered natrocarbonatite lava. An implication of this study is that natrocarbonatite is not just a m...

Magnetic properties of some carbonatites from Tanzania, East Africa

The magnetization of fresh natrocarbonatite lavas from Oldoinyo Lengai in Tanzania is dominated by small amounts of singleor pseudo-single-domain grains of a spinel in the solid solution series jacobsite (MnFe204)-magnetite (Fe304). Although this phase may acquire TRM before carbonatite lava crust has ceased being mobile, the Oldoinyo Lengai samples are good palaeomagnetic recorders of the fiel...

Evidence for the alkaline nature of parental carbonatite melts at Oka complex in Canada.

The Earth's sole active carbonatite volcano, Oldoinyo Lengai (Tanzania), is presently erupting unique natrocarbonatite lavas that are characterized by Na- and K-bearing magmatic carbonates of nyerereite [Na2Ca(CO3)2] and gregoryite [(Na2,K2,Ca)CO3]. Contrarily, the vast majority of older, plutonic carbonatite occurrences worldwide are dominated by Ca-(calcite) or Mg-(dolomite)-rich magmatic car...

An Unusual Lava Cave from Ol Doinyo Lengai, Tanzania