Regional correlation of improved radiocarbon dates from the laminated facies of Antarctic margin sediment from Anvers Trough, Antarctic Peninsula

Immediately overlying glacial till in margin sediments of the western Antarctic Peninsula, a laminated facies consisting of alternating silty (allochthonous, terrigenous) and diatomaceous (autochthonous) ooze is often observed. This laminated facies has been interpreted as the onset of calving bay physiography during deglaciation and, as such, represents a priority for dating in cores that extract the succession of glacial till to pelagic drape marking the last deglaciation. However, the combination of poor carbonate preservation and highly detrital nature of the laminated facies renders it difficult to date. Here, we compare ages from distinct laminae in a series of cores in a shelf-wide transect through the Anvers Trough, a cross-shelf paleo-ice stream trough west of the Antarctic Peninsula. Employing thermochemical separation of acid insoluble organic matter via Ramped PyrOx, we demonstrate age spectrum differences between the types of laminae on the 1 cm scale of core depth. Using this comparison to refine ages of the facies, we construct a regional history of the onset of deglaciation indicating ages at two modes: 9,710 (± 15) ¹⁴C y and 10,470 (± 180) ¹⁴C y. The older deglacial ages were collected from sites in the southern Anvers Trough, while the younger ages are found farther to the north. We suggest that these two modes of geographically distinct deglacial ages indicate separate intervals of regional deglaciation. Through improved dating techniques and regional correlation, it is possible to elucidate the chronology of deglaciation in Antarctic margin sediments and potentially elsewhere.