U-Pb zircon geochronology of the Yellowknife volcanic belt, NWT, Canada: New Constraints on the timing and duration of greenstone belt magmatism

Journal Article · Tue Jan 01 00:00:00 EST 1991 · Journal of Geology; (USA)

DOI:https://doi.org/10.1086/629473· OSTI ID:5667748

Isachsen, S E; Bowring, S A ^[1]; Padgham, W A ^[2]

---

1. Washington Univ., St. Louis, MO (USA)
2. Dept. of Indian Affairs and Northern Development, Yellowknife, Northwest Territory (Canada)

Volcanic and sedimentary rocks in the Slave Province, collectively termed the Yellowknife Supergroup, have long been considered to represent laterally continuous and correlative, stratigraphically coherent homoclinal sequences. Correlation based on the lithologic analysis of certain distinctive units has been most intensely applied to the Yellowknife volcanic belt in the southern Slave Province. U-Pb zircon data for seven samples collected from within the belt are reported here. The distinctiveness of the Townsite Formation, a term applied to three lenticles of rhyodacitic to dacitic tuffs, breccias, and pillowed flows, in comparison to the overlying and underlying tholeiitic basalts (Kam Group), has led to its use as a key marker unit for stratigraphic correlations and palinspastic restorations of offsets on Proterozoic faults in the area. A sample from each of the three segments was collected for U-Pb zircon geochronology. In addition, numerous thinner tuffaceous beds from the Kam Group were also dated. Upper intercept ages of 2,683 {plus minus} 5 Ma, and 2,703 {plus minus} 2 Ma, and 2,705 {plus minus} 3 Ma for the three Townsite segments show that they are not all correlative. Ages of other felsic units from the Kam Group are 2,716 {plus minus} 9 Ma, 2,712 {plus minus} 2 Ma, 2,707 {plus minus} 2 Ma, and 2,688 {plus minus} 3 Ma. These ages are amongst the oldest yet reported for supracrustal rocks in the Slave Province and reveal a protracted magmatic history for the Yellowknife volcanic belt.

• OSTI ID: 5667748
• Journal Information: Journal of Geology; (USA), Vol. 99:1; ISSN 0022-1376
• Country of Publication: United States
• Language: English

Related Subjects

58 GEOSCIENCES
NORTHWEST TERRITORIES
VOLCANIC REGIONS
AGE ESTIMATION
MAGMATISM
ISOTOPE DATING
LEAD ISOTOPES
LITHOLOGY
SEDIMENTARY ROCKS
URANIUM ISOTOPES
VOLCANIC ROCKS
ZIRCON
ACTINIDE ISOTOPES
CANADA
DEVELOPED COUNTRIES
IGNEOUS ROCKS
ISOTOPES
MINERALS
NORTH AMERICA
OXYGEN COMPOUNDS
ROCKS
SILICATE MINERALS
SILICATES
SILICON COMPOUNDS
TRANSITION ELEMENT COMPOUNDS
ZIRCONIUM COMPOUNDS
ZIRCONIUM SILICATES
580000* - Geosciences