Critical Minerals Geology and Exploration

Carbonatite-associated REE Exploration in the Squalus Lake Alkaline Complex

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R. Bachynski (Presenting)
Voyageur Exploration

A preliminary field evaluation of rare earth elements (REE) mineralization in the Squalus Lake Alkaline Complex (SLAC) was undertaken for 9 days in the summer of 2021. The focus of the fieldwork was on identifying and characterizing sources of historical anomalous REE assays contained in assessment and government survey reports.

The Squalus Lake Alkaline Complex is a syenite-dominated concentric Proterozoic intrusion within the Archean Morose Granite. The intrusion is situated along the Phoenix Fault - a major NNE-trending crustal structure. The core of the complex coincides with a regional-scale magnetic high. These features suggest a classic concentric lithological zonation of the complex with a syenite rim and a carbonatite core. The magnetic anomaly is probably associated with a magnetite-rich ferro-carbonatite phase that typically occurs in the cores of most zoned alkaline/carbonatite complexes.

During the fieldwork, evidence for several carbonatite dykes were observed, both in outcrop and in angular float. The dykes are probably emanating from a carbonatite intrusion at the core of the complex, which is interpreted to be underneath Squalus Lake. Sites with reported anomalies were visited and re-sampled. An effort was also made at sampling the different lithological units that were observed.  

Historically anomalous samples (obtained from the previous prospector) have been re-analyzed to confirm the results and attempts are being made at characterizing the potentials of the various host units. In classic alkaline/carbonatite complex models, high grade REE mineralization is generally associated with the younger ferro-carbonatite phase at the core of the complex.

High grade REE mineralization tends to occur in late ferro-carbonatite phases. Previously collected ground-magnetic surveys provide strong discrete targets for the locations of the theorized ferro-carbonatite core, which is a primary target for REE endowment.

Curiously, the ~2180 Ma age of the SLAC is similar to the age of several other alkaline complexes in the Slave structural province, including the Big Spruce Lake Complex (~2188Ma) and the Grace Lake Granite (~2176Ma). The Grace Lake Granite is part of the Blatchford Lake Intrusive Suite, which is host to Canada's first REE mine at the Nechalacho Deposit at Thor Lake.