Section
Physical Sciences
Abstract
There is a pronounced occurrence of gabbroic rocks in the western part of the Lupa gold field, SW Tanzania. These rocks occur in the peripheral part around the Saza-Chuya granodiorite with which it makes a gradiational, unchilled contact. The rocks have been altered or metamorphosed to low-grade greenschist facies as indicated by the presence of secondary epidote, penninite, chlorite, sericite and calcite. The majority of major-element oxides show scattered variation trends against immobile elements such as Zr, indicating some degree of element mobility during post-crystallization processes of alteration or metamorphism. Major-trace-element data show that the gabbroic rocks in the study area are calc-alkaline. REE patterns show that the rocks are highly evolved with a high (La/Yb)N ratio of about 30 and (La/Sm)N ratios of between 18-40. The highly evolved nature of the studied rocks is shown also by low values of magnesium between 56-62%. The gabbroic rocks in the western part of the Lupa gold field seem to have been formed in the continental arc setting.
Recommended Citation
Mnali, SR
(2002)
"Tectonic setting of gabbroic rocks in the western part of the Lupa Gold Field, south-west Tanzania,"
Tanzania Journal of Science: Vol. 28:
Iss.
1, Article 9.
Available at:https://doi.org/10.65085/2507-7961.2075