Supplementary geological datasets to Halpin et al. (2026) "Ediacaran-Cambrian high-strain melt-present deformation of the Archean Charcot Province, East Antarctica" in AGU Tectonics

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Supporting geological data to accompany Halpin et al. "Ediacaran–Cambrian high-strain melt-present deformation of the Archean Charcot Province, East Antarctica” in review with AGU Tectonics. Includes tables of sample details, field observations, whole rock geochemical data, zircon U–Pb data, zircon Hf-isotope data and feldspar Pb–Pb data. These tables are uploaded separately in XLSX format.

Abstract for "Ediacaran–Cambrian high-strain melt-present deformation of the Archean Charcot Province, East Antarctica” in review with AGU Tectonics:

The assembly of Gondwana involved several Pan-African orogens, although their extension into ice-covered Antarctica remains contentious. Particularly problematic is our understanding of the Kuunga orogenic system in East Antarctica, including its eroded architecture and temporal evolution. The remote Charcot Province, at the easternmost extent of the Antarctic Kuunga Orogen, presents a key opportunity to test recent tectonic models. Here we investigate the geological history of Alligator Island, a rarely visited exposure of the Charcot Province. Field relationships, petrography and zircon U–Pb–Hf geochronology indicate that the Alligator Island migmatitic gneisses originated from a Mesoarchean (c. 2.97–2.95 Ga) volcano-sedimentary package. Metamorphism during the Neoarchean (c. 2.76 Ga) was characterised by channelled melt migration. An apparent tectonic quiescence followed until the Ediacaran–Cambrian (580–540 Ma) when high-strain melt-present deformation led to pervasive migmatitic textures and tight folding. Zircon Hf isotopic signatures from anatectic 580–540 Ma grains indicate that melt was sourced from crust older than 3.0 Ga. Melt metasomatism affected whole rock chemistry and feldspar Pb–Pb compositions highlighting complex interactions within the crust. Correlations within the Charcot Province suggest that Alligator Island's Mesoarchean volcano-sedimentary package was deposited on a basement complex possibly represented by Paleo-Mesoarchean gneisses exposed 40–60 km to the east at Cape Charcot and Davis Peninsula. Overall our findings are consistent with a recent model in which Charcot Province rocks formed through gravitational spreading within the Kuunga orogenic system during Gondwana assembly, and enhance our understanding of the tectonic processes shaping East Antarctica.

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Statement: Methods are described in individual supplementary tables as per below: Table S1. (a) Detailed information on individual samples from Alligator Island collected by T. Stål during AAS4318 (2015–17). (b) Raw structural data from Alligator Island collected by J. Halpin and J. Mulder during the Denman Terrestrial Campaign (2023–24). Table S2. Whole rock major and trace element concentrations determined by XRF and solution ICP-MS, including analytical parameters and methodology. Table S3. (a) LA-ICPMS U–Pb zircon data. (b) Metadata for LA-ICPMS U–Pb zircon analysis, including analytical parameters and methodology. Table S4. (a) LA-MC-ICPMS Hf-isotope zircon data. (b) Metadata for LA-MC-ICPMS Hf-isotope zircon analysis, including analytical parameters and methodology. Table S5. (a) LA-ICPMS Pb–Pb feldspar data. (b) Metadata for LA-ICPMS Pb–Pb feldspar analysis, including analytical parameters and methodology.

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Credit
This research was supported by the Australian Research Council Special Research Initiative, Australian Centre for Excellence in Antarctic Science (ACEAS) (Project Number SR200100008) and supported by the Australian Antarctic Program fieldwork that occurred under AAS4318 (2015–17) and AAS4630 (Denman Terrestrial Campaign 2023–24). We thank CODES Analytical Laboratory staff Jay Thompson, Elena Lounejeva and Sean Johnson, and Central Science Laboratory staff Karsten Goemann and Sandrin Feig at UTAS for assistance with the analytical work undertaken during this study. Yoann Greau is thanked for facilitating analysis at Macquarie GeoAnalytical. We thank Michael Roach (UTAS) for creating the 3D image of Alligator Island.