Unraveling recycling and climate influence on detrital U-Pb geochronology of titanite and apatite: An example from the Gaskiers Glaciation in Newfoundland

Detrital zircon geochronology is a valuable tool for detecting changes in sediment provenance. However, fertility and reworking biases can obscure the identification of distinct detritus sources during glaciation in complex tectonic settings. Apatite and titanite U-Pb geochronology offers a more versatile option, covering a more comprehensive range of host rocks and closure temperature conditions, although weathering and diagenesis majorly affect mineral stability. Decoupling between multi-proxy age spectra and associated trace element variations provides an opportunity to elucidate the effects of glacial conditions on mineral stability and preservation. Here, we used detrital apatite and titanite U-Pb geochronology and trace element geochemistry from Ediacaran glaciogenic strata of the Gaskiers Glaciation in the Bonavista Peninsula of Newfoundland (Avalon Zone) to better understand sediment recycling and source-to-sink dynamics during glacial events.

Apatite age spectra from the ca. 590 Ma fluvio-glacial Jones Pond and Plate Cove East members yield dominantly 660–630 Ma U-Pb apatite ages. In contrast, apatite spectra from the ca. 590–580 Ma proximal glaciomarine Monk Bay Member and the overlying ca. 580 Ma deglacial Trinity Diamictite are dominated by ca. 600–580 Ma grains, closely approximating depositional ages. The paucity of Ediacaran detrital apatite in periglacial conglomerates compared to their presence of these grains in deglacial strata reflects their preferential dissolution under acidic weathering conditions, implying the advance of glaciers over the Avalonian catchment from ca. 590 to 580 Ma.

Detrital titanite preserves Archean, Mesoproterozoic, and Tonian single-grain U-Pb ages throughout the same succession, corroborating contributions from older sources within the otherwise Cryogenian–Ediacaran volcanic arc-dominated West Avalonia assemblage. Long-transported detritus is rare, whereas polycyclic apatite and titanite in the studied units indicate a direct sedimentary link between the underlying Connecting Point Group and its Baltican and/or Amazonian cratonic basement sources. Furthermore, detrital titanite results suggest hydrothermal activity and low-grade metamorphic overprints of ca. 540 and 400 Ma, the latter akin to the Acadian Orogeny that affected West Avalonia.