A multi-proxy reconstruction of environmental change spanning the last 37,000 years from Burial Lake, Arctic Alaska

Abstract

a b s t r a c tSediment cores from Burial Lake located in the western Brooks Range in Arctic Alaska record paleoenvironmental changes that span the last 37,000 calendar years before present (cal yr BP). We identified four distinct lithologic subunits based on physical properties (dry bulk density, magnetic susceptibility), sediment composition, and geochemical proxies (organic matter, biogenic silica, C/N, organic matter d 13 C and d 15 N, and elemental data from scanning X-ray fluorescence). The multi-proxy approach and relatively high temporal resolution (at multi-decadal to centennial time scales) of our proxy analysis, compared with previous studies of intermediate water depth cores from Burial Lake, provide new insights into the paleoenvironmental history of the region spanning the period prior to the Last Glacial Maximum. Relatively high lake-levels and gradually decreasing in-lake and terrestrial productivity occur during the mid-Wisconsin interstadial from 37,200 to 29,600 cal yr BP. The subsequent period is defined by falling and lower lake-levels with decreasing effective-moisture, windier conditions, and sustained low aquatic productivity throughout the LGM between 29,600 and 19,600 cal yr BP. The last deglaciation that commenced by 19,600 cal yr BP is characterized by gradual changes in several sediment physical and geochemical proxies, including increasing C/N ratios and terrestrial productivity, decreasing magnetic susceptibility and clastic sediment flux, along with rising and relatively higher lake-levels. A decrease in aeolian activity after 16,500 cal yr BP is inferred from the appearance of fine (very fine sandy silt) sediment, compared to coarse sediments through the LGM and last deglaciation. The highest levels of terrestrial inputs along with increasing and variable aquatic productivity occur during the Lateglacial to early Holocene interval between 16,500 and 8800 cal yr BP. The absence of multi-proxy evidence for a strong climatic reversal during the Younger Dryas from Burial Lake sediments contrasts with some paleorecords showing cooler temperatures and/or dry conditions in northern Alaska at this time. Peak levels of sediment organic content and terrestrial productivity at Burial Lake between 10,500 and 9900 cal yr BP coincide with the early Holocene summer insolation maxima, which likely represents summertime warming and an enhanced flux of watershed derived organic matter from permafrost degradation. The remainder of the Holocene (since 8800 cal yr BP) at Burial Lake is characterized by relatively high and stable lake levels, landscape stabilization, and relatively high and variable levels of aquatic productivity.

Middle to late Wisconsinan climate and ecological changes in northern Alaska: Evidences from the Itkillik River Yedoma

“…The climatic reconstruction suggests Itkillik site experienced a warmer interval from 36 to 33.6 cal kyr BP. In agreement with our observations, higher lake levels are reported across interior and northern Alaska between 37.2 and 33 cal kyr BP (Finkenbinder et al, 2015). This is occurring 2-3 kyr prior to the warm interval reconstructed from the Fox permafrost tunnel record in interior Alaska (from 33 to 34 to 30 kyr BP) (Hamilton et al, 1988).…”

Vegetation response to abrupt climate changes in Western Europe from 45 to 14.7k cal a BP: the Bergsee lacustrine record (Black Forest, Germany)

“…The close link between climate and vegetation is also manifested in continental records from America (e.g. Abbott et al ., ); Finkenbinder et al ., ; Fischer et al ., ), Asia (e.g. Park et al ., ) and Europe (e.g Guiter et al ., ; Feurdean et al ., ; Birks and Birks, ; Pickarski et al ., ).…”

Sedimentary biomarkers reaffirm human impacts on northern Beringian ecosystems during the Last Glacial period

“…; Finkenbinder et al . ). The lake is deep (21.5 m) and small (0.8 km 2 ), with a relatively small watershed (3.3 km 2 ), one outlet stream, and several seasonally ephemeral inlets (Finkenbinder et al .…”

“…), Burial Lake is one of a small number of lakes that persisted during the cold and arid Last Glacial period (Finkenbinder et al . ). As such, sediments from E5 and Burial are valuable environmental archives.…”