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Title AGES OF PEGMATITE AND VEIN MINERALS FROM RWANDA AND BURUNDI
Creator/Author Cahen, L. ; Delwiche, R. ; Monteyne-Poulaert, G.
Publication Date1962 Jan 01
OSTI IdentifierOSTI ID: 4680713
Resource TypeJournal Article
Resource RelationBull. Soc. Belge Geol., Paleontol., Hydrol.; Vol: 71: No. 2; EUR 200.f
Research OrgMusee Royal de l`Afrique Centrale, Tervuren, Africa
SubjectGEOLOGY, MINERALOGY, AND METEOROLOGY; AGE ESTIMATION; ALUMINUM SILICATES; CALCIUM OXIDES; DISTRIBUTION; FELDSPARS; GALENA; GEOCHEMISTRY; GEOLOGY; LEAD ISOTOPES; LEAD SULFIDES; LEPIDOLITE; LITHIUM COMPOUNDS; MICA; MICROCLINE; MICROLITE; MINERALS; MUSCOVITE; NIOBIUM; NIOBIUM OXIDES; POTASSIUM SILICATES; PYROCHLORE; QUARTZ; ROCKS; RUBIDIUM ISOTOPES; SODIUM OXIDES; STRONTIUM ISOTOPES; TANTALUM; TANTALUM OXIDES; TIN; TITANIUM OXIDES; URANIUM ISOTOPES; URANIUM MINERALS
Description/Abstract BS>Presented is part of a program dealing with the ages of pegmatite and vein minerals from the Kibara-UrundiKaragwe Ankolean belt. Ages of sixteen pegmatite and vein minerals from Rwanda and Burundi were obtained by the strontium-- rubidium ( lambda = 1.47 x 10/sup -11/ yr/sup -1/), lead--uranium, and common lead methods. These ages fall into two groups. Eleven muscovites, one microcline, and one common lead, from tin and niobium-- tantalum-bearing pegmatites and veins (8 localities in Rwanda and 3 in Burundi), yield apparent and conventional ages between 870 and 1,000 m.y. Three Sr--Rb determinations on lepidolites from similar pegmatites from Northern Katanga, comprised in the expression 920 plus or minus 25 m.y., which lies in the range obtained in Rwanda and Burundi, are included for comparison. As the range from 870 to 1,000 m.y. is greater than the uncertainty of each measurement, it is probable that these pegmatites and veins do not represent one single event and that part of the scatier is real. The age range 870 to 1,000 m.y. characterizes pegmatites and veins which are post-tectonic events of the Urundian or Karagwe-Ankolean cycle. The occurrences from Northern Katanga are posttectonic events of the equivalent Kibara cycle. One, or two, much younger events are indicated by minerals found or thought to occur in quartz veins which are emplaced in the above-mentioned pegmatites. A mineral of the microlitepyrochlore group from Buranga is circa 555 m.y. old and a galena from Kababara has a common lead conventional age of 620 plus or minus 50 m.y. These figures occur in the range of Katangan and post-Katangan ages. The quartz veins therefore appear to be much younger than the host pegmatites. As this question is of interest to metallogeny it will be further investigated. A galena from Rushubi (Burundi) has a lead of anomalous isotopic constitution. (auth)
LanguageFrench
FormatPages: 1-13
System Entry Date2001 Jun 03

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