ABSTRACT: Quaternary geology of southern Melville Peninsula, Nunavut: surface deposits, glacial history, environmental geology, and till geochemistry.

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Abstract

Quaternary glaciations have created sandy granitic till, calcareous silty till, calcareous glaciomarine deposits, raised marine beaches, and scoured rock outcrop. Accompanying maps are used to reconstruct glacial history. Limestone erratics on uplands suggest extensive Foxe Ice prior to the last glaciation. Clay minerals in regolith and upland block fields indicate an ensuing weathering interval, followed by a periglacial period. During the Foxe (=Wisconsin) Glaciation, ice on uplands coalesced to form a local ice sheet (Melville Ice). This ice sheet was later subsumed by Foxe Ice, although a subsidiary divide persisted on the peninsula, blocking and diverting Foxe Ice flow. Cold-based zones and local ice divides preserved the regolith on the plateaus. Some areas gradually became warm-based. Deglaciation began with penetration of a marine re-entrant south of Wales Island about 8600 years ago, with ice streaming through Rae Isthmus and development of Melville Moraine as far south as Matheson River. Marine limit elevations suggest rapid, progressive breakup of Foxe Ice 6800-7000 years ago. Ice remaining on the peninsula flowed radially to the coasts as late as 6400 years ago, and gradually retreated inland. Remnants eventually stagnated near Haviland Bay and Aua River. Abundant subglacial and ice-marginal meltwater features characterized deglaciation. Geochemical signatures from till and gossan samples are related to rock lithology, directions and styles of glacial transport, and length of time available for weathering. Tills within areas controlled by Foxe Basin ice are far-travelled, while those beneath the Melville Ice divide reflect the composition of underlying rock types. Lead/zinc ratios in regolith, till, and gossans indicate postglacial geochemical reactivity. Gossans associated with Zn, Cd, Ni, and Cu anomalies are preferentially found in rocks of the Prince Albert Group, and schist-marble contacts in the Penrhyn Group.

Bibliography of Canadian Geomorphology