Late Holocene paleoclimatic and paleoceanographic records in anoxic basins, Seymour-Belize Inlet Complex, British Columbia

Geochemical, foraminiferal and thecamoebian proxies archived in two piston and a freeze cores from glacier-carved fjords in the Seymour-Belize Inlet Complex (SBIC), British Columbia coast, were utilized to investigate fluctuations in the late Holocene regional paleoclimate and paleoceanography. The investigated piston cores from Frederick Sound (FS) and Alison (ALS) Sound are predominantly composed of organic-rich mud/silt sediments mainly deposited as annually laminated and massive intervals interspersed by occasional slump and graded sediments. The Mereworth Sound (MS) freeze core is characterized by monotonous mud/silt sediments with a substantial sand component occurring in the uppermost 68.5-0 cm (1248-2002 cal AD) interval.The distribution of delta13C and delta15N stable isotopes, laminae thickness and foraminiferal species in the FS and ALS cores suggest the existence of periodic alternations between cool/wet and cooler/dry climate conditions in the SBIC. A dramatic shift to heavier delta 13C and lighter delta15N values at 3135 cal yr BP (FS core) and 2462 cal yr BP (ALS core), respectively, indicates a regime change to cooler/dry regional climate conditions which corresponds to the late Holocene Neoglacier advance in the Northeast Pacific.A high enrichment of redox-sensitive elements and dearth of foraminiferal species within the 577-1248 cal AD interval in the MS indicates that the late Holocene bottom water anoxia-suboxia persisted until the mid of the 13th century in the SBIC. Bottom water conditions during this interval were likely similar to those that existed during the Medieval Warm Period (MWP). A regime change to high oxic, cooler climate conditions corresponding to the Little Ice Age (LIA) events occurred from 1248-1386 cal AD. The overall regional LIA cool climate conditions in the SBIC were punctuated by a short warm episode during the late 14th through early 16th century (1386-1518 cal AD). The topmost 1518-202 AD interval in the MS core was marked by cool climate conditions, suggesting that the LIA events in the SBIC region occurred in two stages.The overall high concentrations of redox-sensitive elements and preponderance of low oxygen-tolerant agglutinated foraminiferal species in the piston cores are interpreted as indication that the bottom waters in the SBIC were characterized by low oxygen levels during the late Holocene. Cluster analysis of the piston core samples discriminated three biofacies in the FS core and two in the ALS core. In addition, a total of four biofacies were recognized in the MS freeze core.