| The wealth of our knowledge of late Quaternary environments in the Canadian Arctic Archipelago (CAA) has been terrestrially based, despite the prominence of marine channels. Two long cores from central Parry Channel extending to the last glaciation (Lancaster Sound/Barrow Strait: core 86027-154; southeastern Barrow Strait: 86027-144), and one boxcore from the southwest CAA (Coronation Gulf: 99LSSL-001) provide important information on marine palaeoenvironments since deglaciation to the present day. Long cores were studied for sedimentological characteristics, organic-walled (dinocysts; non-pollen palynomorphs) and calcareous (benthic and planktonic foraminifera, ostracods) microfossils, and foraminiferal stable isotopes (delta18O, delta 13C; core 86027-144 only); being chronologically constrained by 29 radiocarbon dates. Both records suggest grounded glacial ice, followed by rapid deglaciation and a distinct progression from ice-proximal to ice-distal conditions, itself interrupted by pervasive landfast sea ice. The timing of deglaciation is complicated by an absence of dateable materials at the diamict/glaciomarine transition, the Portlandia Effect and DeltaR values for calibration. Age model extrapolations suggest central Parry Channel deglaciation at ∼12.1-11.0 cal ka BP (maximum) or 10.3-10.2 cal ka BP (minimum). Biological activity commences in the early Holocene, with a prominent signal of planktonic foraminifera. This marks the penetration of deeper Atlantic waters into the archipelago following deglaciation, likely facilitated by higher sea levels permitting increased flow across inter-channel sills. Postglacial amelioration (open-water season greater than present) at ∼9-7 cal ka BP potentially corresponds to a regional "Holocene Thermal Optimum". The exclusion of deep Atlantic water due to glacioisostatic shallowing, coupled with generally cooling climate, eventually leads to increased sea ice and modern microfossil assemblages, analogous conditions commencing at ∼6 cal ka BP. Shorter-term climatic signals (e.g. Little Ice Age, LIA) were not recognized in the long cores, in contrast to boxcore 99LSSL-001 studied for sedimentological characteristics and organic-walled microfossils (dinoflagellate cysts, non-pollen palynomorphs). The latter indicates less sea ice ∼1470-1680 AD, followed by LIA cooling, and 20th century (post 1940 AD) warming. The late Holocene discrepancy between Parry Channel and Coronation Gulf may be due to climatological (Low vs. High Arctic), geographical (east vs. west), or resolution factors.;... |
