Abstract
The Lupa Goldfield (LGF) is one of the eight structural terranes in the NW – SE striking Ubendian Belt of SW Tanzania. The LGF is comprised of granitic gneisses with bands of amphibolites which are intruded by mafic intrusions including gabbros, granodiorites, diorites; and various granites as well as metavol-canics. These rocks are cross-cut by narrow mafic dykes and aplites. SHRIMP zircon U-Pb data are presented for the granodiorite and a mafic dyke that cross-cut the granodiorites in the Saza area of the LGF, with the aim of constraining the mafic and felsic magmatism and their implication to gold mineralization. The zircon U-Pb data shows that the Saza granodiorites were emplaced at 1924 ± 13 Ma (MSWD = 2.6) whereas the cross-cutting mafic dyke yielded a zircon U-Pb age of 1758 ± 33 Ma (MSWD = 0.88). The dated granodiorite sample was in sheared contact with an altered mafic intrusive rock, most likely a diorite, along which an auriferous quartz vein occurs. The 1924 ± 13 Ma age of granodiorites is within error of the reported molybdenite Re-Os age of 1937 Ma determined for the gold mineralization event in Lupa Goldfields. Although auriferous quartz veins are younger than the granodiorites, the more or less similar ages between the emplacement of granodiorites and the mineralizing event indicate that the granodiorites might be the heat source (or driver) of hydrothermal fluids responsible for gold mineralization in the Lupa goldfields. This would further suggest that gold mineralization in the LGF is intrusion-related type. The mafic dykes represent the youngest rocks to have been emplaced in the area and hence the 1758 ± 33 Ma age of the mafic dykes conclude the magmatic evolution in the Lupa goldfields during the Palaeoproterozoic.
Highlights
The NW-SE Ubendian Belt of SW Tanzania is bordered by the Tanzania Craton to the northeast and the Bangweulu Block to the southwest (Figure 1)
Boniface et al [4]. showed that the Ubende eclogites show a MORB-like chemistry and yielded SHRIMP zircon U-Pb ages of 1886 ± 16 and 1866 ± 14 Ma suggesting the existence of a Palaeoproterozoic ocean floor subduction in the Ubendian Belt
This paper presents the SHRIMP zircon U-Pb ages for the Saza granodiorite and a mafic dyke with the aim of better constraining the emplacement ages of the mafic and felsic igneous intrusion events in the Saza area of the Lupa Goldfield (LGF) and their implication to gold mineralization
Summary
The NW-SE Ubendian Belt of SW Tanzania is bordered by the Tanzania Craton to the northeast and the Bangweulu Block to the southwest (Figure 1). The Belt has been subdivided, on the basis of structural and lithological differences into 8 blocks (or terranes) namely: Ubende, Wakole, Katuma, Ufipa, Upangwa, Nyika, Mbozi and Lupa [2,3] (Figure 1). Dominant lithologies in other terranes include alumino-silicate schists for Wakole, migmatitic biotite gneisses (Katuma), mafic granulites and syenites (Mbozi), meta-anorthosites (Upangwa), and cordierite gneisses (Nyika). This paper presents the SHRIMP zircon U-Pb ages for the Saza granodiorite and a mafic dyke with the aim of better constraining the emplacement ages of the mafic and felsic igneous intrusion events in the Saza area of the LGF and their implication to gold mineralization. The data shows that the mafic dykes cross-cutting the granodiorites were emplaced at 1758 ± 33 Ma and this concludes the magmatic evolution of the Lupa Goldfields during the Palaeoproterozoic
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
