Last modified:
Translation of original French
| Author: | Lamothe, 1994 |
| Age: | Paleoproterozoic |
| Reference section: | None |
| Type area: | Chukotat Lake area (NTS sheet 35G05) |
| Geological province: | Churchill Province |
| Geological subdivision: | Ungava Orogen / Ungava Trough / Southern Domain |
| Lithology: | Volcano-sedimentary rocks |
| Type: | Lithostratigraphic |
| Rank: | Formation |
| Status: | Formal |
| Use: | Active |
Background
This unit was named by Lamothe (1994) to describe a sedimentary bed at the top of the Povungnituk Group. It was previously a member of the Beauparlant Subgroup, which is now reduced to the rank of formation (Moorhead, 1989, 1996a, b).
Description
The Nuviliq Formation is an allochthonous assemblage of sandstone, siltstone, limestone, dolomitic limestone and volcaniclastics forming the upper part of the Povungnituk Group, in the Southern Domain. Siltstone represents the unit’s most abundant lithology. Phyllite and slate beds are interstratified between siltstone beds. Several mafic to ultramafic sills of the Lac Esker Suite intrude into sedimentary rocks. The central portion of the Nuvilic Formation has an abundance of decimetric beds of fine-grained or lapilli tuff, likely of epiclastic nature (Moorhead, 1996a). Near the contact with the Chukotat Group, there is a concentration of disseminated to massive pyrrhotite and pyrite mineralization in fine-grained sedimentary beds. Massive sulphide layers, locally brecciated, likely synchronous to sedimentation, contain anomalous values in zinc, copper, nickel and light rare earths (Giovenazzo et al., 1991). Concentrations of light rare earths are presumably due to the detrital input associated with the erosion of the Cécilia Formation’s alkaline volcanic edifice (Giovenazzo et al., 1991).
Nuvilic Formation 1 (pPnu1): Sandstone, Siltstone
Little information is available.
Nuvilic Formation 2 (pPnu2): Limestone, Dolomitic limestone
Little information is available.
Thickness and Distribution
The Nuvilic Formation extends laterally over 100 km in the central part of the Southern Domain.
Dating
None.
Stratigraphic Relationship(s)
The Nuvilic Formation structurally overlies the Cécilia Formation in the central part of the Southern Domain. Petrographic and lithochemical evidence suggests that the Nuvilic Formation represents distal accumulation in a relatively deep environment of detrital sediments from the erosion of the Cécilia Formation and ash deposits resulting from the latter’s volcanism (Moorhead, 1996a; Giovzzenao et al., 1991). If this is the case, the Nuvilic Formation would be contemporary with the Cécilia Formation dated 1958.6 +3.1/-2.7 Ma (Parrish, 1989). The contact between the Nuvilic Formation and the overlying Chukotat Group corresponds to a thrust fault (Moorhead, 1996a).
Paleontology
Does not apply.