Gold deposits in the late Archaean Nzega-Igunga greenstone belt, central plateau of tanzania

Conference · Tue Jan 01 00:00:00 EST 1985 · Geol. Soc. Am., Abstr. Programs; (United States)

OSTI ID:6611339

Feiss, P G; Siyomana, S

2.2 m oz of gold have been produced, since 1935, from late Archaean (2480-2740 Ma) greenstone belts of the Central Plateau, Tanzania. North and east of Nzega (4/sup 0/12'S, 3/sup 0/11'E), 18% of the exposed basement, mainly Dodoman schists and granites, consists of metavolcanics and metasediments of the Nyanzian and Kavirondian Series. Four styles of mineralization are observed. 1. Stratabound quartz-gold veins with minor sulfides. Host rocks are quartz porphyry, banded iron formation (BIF), magnetite quartzite, and dense, cherty jasperite at the Sekenke and Canuck mines. The Canuck veins are on strike from BIF's in quartz-eye porphyry of the Igusule Hills. 2. Stratabound, disseminated gold in coarse-grained, crowded feldspar porphyry with lithic fragments and minor pyrite. At Bulangamilwa, the porphyry is conformable with Nyanzian-aged submarine (.) greenstone, volcanic sediment, felsic volcanics, and sericite phyllite. The deposits are on strike with BIF of the Wella Hills, which contains massive sulfide with up to 15% Pb+Zn. 3. Disseminated gold in quartz-albite metasomes in Nyanzian greenstones. At Kirondatal, alteration is associated with alaskites and feldspar porphyry dikes traceable several hundred meters into post-Dodoman diorite porphyry. Gold is with pyrite, arsenopyrite, pyrrhotite, minor chalcopyrite, and sphalerite as well as tourmalinite and silica-cemented breccias. 4. Basal Kavirondian placers in metaconglomerates containing cobbles and boulders of Dodoman and Nyanzian rocks several hundred meters up-section from the stratabound, disseminated mineralization at Bulangamilwa.

• Research Organization: Univ. of North Carolina, Chapel Hill (USA)
• OSTI ID: 6611339
• Report Number(s): CONF-8510489-
• Journal Information: Geol. Soc. Am., Abstr. Programs; (United States), Vol. 17; Conference: 98. annual meeting of the Geological Society of America, Orlando, FL, USA, 28 Oct 1985
• Country of Publication: United States
• Language: English

Related Subjects

58 GEOSCIENCES
GOLD ORES
MINERALIZATION
MINERALOGY
PETROLOGY
TANZANIA
FELDSPARS
MAGNETITE
PRECAMBRIAN ERA
QUARTZ
SCHISTS
SULFIDE MINERALS
AFRICA
CHALCOGENIDES
DEVELOPING COUNTRIES
GEOLOGIC AGES
GEOLOGY
IRON COMPOUNDS
IRON ORES
IRON OXIDES
METAMORPHIC ROCKS
MINERALS
ORES
OXIDE MINERALS
OXIDES
OXYGEN COMPOUNDS
ROCKS
SILICON COMPOUNDS
SILICON OXIDES
TRANSITION ELEMENT COMPOUNDS
580300* - Mineralogy
Petrology
& Rock Mechanics- (-1989)