Using a recent compilation of African alkaline igneous rocks and carbonatites, we show that nearly 90% (28 of 32 occurrences) of nepheline syenite gneisses and deformed carbonatites are concentrated within known or inferred Proterozoic suture zones. Given the wellestablished intracontinental rift setting for these rocks and the likely continental collisional setting for their subsequent deforma...

The rate of K+ leaching from soil minerals such as K-feldspar is believed to be too slow to provide agronomic benefit. Currently, theories and methods available to interpret kinetics of mineral processes in soil fail to consider its microfluidic nature. In this study, we measure the leaching rate of K+ ions from a K-feldspar-bearing rock (syenite) in a microfluidic environment, and demonstrate ...

Ilmenite-group titanates are relatively common accessory minerals in agpaitic nepheline syenite (lujavrite) in the Pilansberg alkaline complex, South Africa. They crystallized in three generations and form a continuous ecandrewsite – pyrophanite solidsolution extending from (Zn0.81Mn0.12Fe0.07)TiO3 to (Mn0.93Fe0.7)TiO3. The earliest generation of ferroan manganoan ecandrewsite of widely varying...

High-spatial-resolution (230Th)/(238U) disequilibrium dating reveals rapid zircon crystallization prior to the 12,900 yr B.P. Laacher See (Germany) phonolite eruption. Zircons from Lower Laacher See tephra (LLST) and syenitic subvolcanic nodules share REE and low U/Th characteristics and define an isochron age of 17.1 1.3 ka (1 ). Zircons also show higher initial (Th)/(Th)0 and oxygen isotopic ...

Plagioclase crystal fragments and a block of anorthosite occur in small basaltic dykes on the Jos Plateau. The anorthosite is unusual, for the feldspar is labradoritic, but the interstitial mineralogy is granitic rather than basic, displaying granophyric intergrowths in places. The anorthosite is probably not an intermediate stage in fractionation from a basic parent magma towards granite, sinc...

The accessory mineral assemblage (AMA) of igneous cumulate xenoliths in volcanoclastic deposits and lava flows the Carpathian back-arc basin testifies to composition intrusive complexes sampled by Upper Miocene-Pliocene basalt volcanoes. magmatic reservoir beneath Pinciná maar is composed gabbro, moderately alkalic alkali-calcic syenite, calcic orthopyroxene granite (pincinite). complex wider a...

Some silicate rocks are a rich source of potassium (K), with the possibility for use in agriculture. The present study aimed to evaluate agronomic efficiency index (AEI) nepheline syenite (NS) and phonolite (PN) comparison chloride (KCl) as K maize production. An experiment was conducted greenhouse Ilha Solteira, São Paulo, Brazil. A hybrid grown 8 L pots filled 6 kg soil low concentration cont...