A sedimentary basin analysis of the Abitibi Greenstone belt in the Timmins area, northern Ontario, Canada

In the Timmins area, the uppermost part of the Abitibi Greenstone belt consists of deep-water, alluvial-fluvial, and minor shelf deposits within a small (1000 km;Point-count data for sandstones of all formations have yielded several key grain types that are useful for interpreting provenance and tectonic setting for each of ten depositional environments. QFL, QmFLt and QmFLq diagrams for the Timmins data indicate the predominant source area to be a complex basement uplift with minor contribution from deeply eroded volcanic arcs. In general, sediments from the various formations can be separated on the basis of characteristic ratios for the key grain types.;Data from polycrystalline quartz (Qp) diagrams show a large diversity of polycrystalline quartz, including up to 5 types in the Pamour Group reflecting a complex source region.;In conjunction with sedimentology, REE (Rare Earth Element) geochemistry is a powerful tool for solving geological problems related to provenance. The average calculated value for all ten depositional environments is 95% felsic volcanic and 5% mafic volcanic, but one data sub-set shows that the deep-water deposits contain 30% mafic volcanic and 70% felsic volcanic, and another data subset shows that the shallow-water and fluvial sediments (Pamour Group) have REE values near 100% felsic volcanic, because they were derived from a highly fractionated felsic volcanic (or tonalitic) source.;Similarities in slopes and shapes of the REE curves for all environments suggest that a large source area must have been exposed for 30-40 million years. It also implies that erosion and deposition occurred in a typical continental setting such as a pull-apart basin adjacent to a major structural intraplate boundary such as the Porcupine-Destor Deformation Zone, rather than in an accretionary sedimentary basin such as an island arc or a forearc basin.