Till geochemical data for the Brazil Lake pegmatite area, southwest Nova Scotia, Canada (NTS 21-A/04, 20-O/16 and 20-P/13): samples collected in 2020, 2021, and 2022

Abstract

This open file reports geochemical data for till samples collected as a part of a till geochemical and surficial mapping project around the Brazil Lake lithium-cesium-tantalum (LCT-type) pegmatite in southwestern Nova Scotia (NTS map sheets 21A/04, 20O/16 and 20P/13). The global rise in lithium demand has motivated the Geological Survey of Canada's (GSC) recent investigations of the Brazil Lake pegmatites to study surficial geochemistry methods that can be used to explore for lithium and associated critical minerals (i.e., Cs, Ta, Be, In, Sn, W). These types of deposits are important sources of lithium, tin, and rubidium and the primary source of tantalum. This research at Brazil Lake is being undertaken as part of the GSC's Targeted Geoscience Initiative Program and has been carried out in partnership with the Nova Scotia Department of Natural Resources and Renewables (NSDNRR). The goals of the research are to increase exploration success in regions covered by glacial sediments by documenting how critical minerals and associated elements are glacially dispersed in till from pegmatites at the Brazil Lake property. Newly available LiDAR data assisted in deciphering ice flow trajectories, which in turn, allowed for targeted till sampling. A total of 184 till samples were collected for till geochemistry in 2020, 2021 and 2022 and the data reported here include widely spaced regional samples collected across southwest Nova Scotia, proximal samples collected up-ice, overlying, and down-ice of the Brazil Lake pegmatites. The widely spaced till samples provide the regional context for the interpretation of the case study samples and assess the potential for additional pegmatites buried by extensive till cover. Data reported in this Open File include sample descriptions, location, site photos, and geochemical analyses of the coarse sand (1.0 - 2.0 mm) and silt + clay (<0.063 mm) fractions. For the 2020 samples only, the <0.002 mm (clay) fraction was also analyzed. Analyses over the 3 years (2020-2021-2022) include various combinations of different digestions or fusions to test and compare their efficacy for the various pathfinder elements for LCT pegmatites: aqua regia (partial) digestion, 2) Na peroxide fusion (total), 3) 4-acid (near total) digestion, 4) Li-meta/tetraborate fusion, 5) loss on ignition, and 6) portable X-ray fluorescence (XRF).