Age models and tephrostratigraphy from two lakes on Adak Island, Alaska

Krawiec, Anne C.L.; Kaufman, Darrell S.; Vaillencourt, D.

doi:10.1016/j.quageo.2013.07.002

Cited by 13 publications

(24 citation statements)

References 21 publications

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“…The core was split, photographed and described (Krawiec, ), with 20 samples taken downcore for δ 18 O diatom and diatom species analysis. The samples range in age from 8.0 to 1.0k cal a BP based on a best‐fit age–depth model constructed using accelerator mass spectrometry 14 C ages and correlated tephra ages from nearby Andrew Lake (Krawiec et al ., ).…”

Section: Methodsmentioning

confidence: 97%

The effect of species on lacustrine δ¹⁸ O_diatom and its implications for palaeoenvironmental reconstructions

et al. 2014

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The oxygen isotope composition of diatom silica (d 18 O diatom ) is increasingly being used to reconstruct climate from marine and lacustrine sedimentary archives. Although diatoms are assumed to precipitate their frustule in isotopic equilibrium with their surrounding water, it is unclear whether internal processes of a given species affect the fractionation of oxygen between the water and the diatom. We present d 18 O diatom data from two diatom size fractions (3-38 and >38 mm) characterized by different species in a sediment core from Heart Lake, Alaska. Differences in d 18 O diatom between the two size fractions varies from 0 to 1.2‰, with a mean offset of 0.01‰ (n ¼ 20). Fourier transform infrared spectroscopy confirms our samples consist of pure biogenic silica (SiO 2 ) and d 18 O diatom trends are not driven by contamination. The maximum offset is outside the range of error, but the mean is within analytical error of the technique (AE 1.06‰), demonstrating no discernible speciesdependent fractionation in d 18 O diatom . We conclude that lacustrine d 18 O diatom measurements offer a reliable and valuable method for reconstructing d 18 O water . Considering the presence of small offsets in our two records, we advise interpreting shifts in d 18 O diatom only where the magnitude of change is greater than the combined analytical error.

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Section: Methodsmentioning

confidence: 97%

The effect of species on lacustrine δ¹⁸ O_diatom and its implications for palaeoenvironmental reconstructions

et al. 2014

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“…Our study focuses on the longest percussion core (10-AS-1D; 5.9 m) and two accompanying surface gravity cores (09-AS-1A, 0.81 m; and 09-AS-1B, 0.44 m). For a detailed description of the sediment core's lithostratigraphy, see Krawiec et al (2013).…”

Section: Sediment and Water Recoverymentioning

confidence: 99%

“…The composite age model for 10-AS-1D and 09-AS-1A is presented in a separate paper devoted to the tephrostratigraphy and radiometric dating of the Heart Lake sedimentary sequence (Krawiec et al 2013) ( Supplementary Fig. 3a).…”

Section: Chronologymentioning

confidence: 99%

Holocene atmospheric circulation in the central North Pacific: A new terrestrial diatom and δ18O dataset from the Aleutian Islands

Bailey

Kaufman

Sloane

et al. 2018

Quaternary Science Reviews

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a b s t r a c tThe North Pacific is a zone of cyclogenesis that modulates synoptic-scale atmospheric circulation, yet there is a paucity of instrumental and paleoclimate data to fully constrain its long-term state and variability. We present the first Holocene oxygen isotope record (d 18 O diatom ) from the Aleutian Islands, using siliceous diatoms preserved in Heart Lake on Adak Island (51.85 N, 176.69 W). This study builds on previous work demonstrating that Heart Lake sedimentary d 18 O diatom values record the d 18 O signal of precipitation, and correlate significantly with atmospheric circulation indices over the past century. We apply this empirical relationship to interpret a new 9.6 ka d 18 O diatom record from the same lake, supported by diatom assemblage analysis. Our results demonstrate distinct shifts in the prevailing trajectory of storm systems that drove spatially heterogeneous patterns of moisture delivery and climate across the region. During the early-mid Holocene, a warmer/wetter climate prevailed due to a predominantly westerly Aleutian Low that enhanced advection of warm 18 O-enriched Pacific moisture to Adak, and culminated in a d 18 O diatom maxima (33.3‰) at 7.6 ka during the Holocene Thermal Maximum. After 4.5 ka, relatively lower d 18 O diatom indicates cooler/drier conditions associated with enhanced northerly circulation that persisted into the 21st century. Our analysis is consistent with surface climate conditions inferred from a suite of terrestrial and marine climate-proxy records. This new Holocene dataset bridges the gap in an expanding regional network of paleoisotope studies, and provides a fresh assessment of the complex spatial patterns of Holocene climate across Beringia and the atmospheric forces driving them.

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“…From the section Radiocarbon Dating and Sedimentation Rate (p. 1487): Okuno et al (2012) and Krawiec et al (2013) reported eruption ages of 0.4, 3.6, 6.0, and 9.5 cal ka BP for 40YR, YBO, ITM, and MAN, respectively.…”

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confidence: 99%

Vegetation Changes around Haven Lake, Adak Island, Central Aleutians, Alaska, Determined from Pollen Analysis

et al. 2018

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We collected peat sediments (sediment core ADK13083002) from Haven Lake on the north side of Adak Island (central Aleutian Islands, Alaska) to determine whether the vegetation has changed. We confirmed the presence of six tephra layers, including Forty Years (0.3 cal ka BP), T2, YBO (3.3 cal ka BP), Intermediate (6.4 cal ka BP), Main (9.5 cal ka BP), and T6. We identified four major pollen assemblage zones (HL-1 to HL-4, in descending order) in the cored sediment. HL-1 was dominated by Ranunculaceae and Empetrum pollen; H-2 was dominated by Poaceae, Ranunculaceae, and Empetrum pollen; HL-3 was dominated by Poaceae and Empetrum pollen; and HL-4 was dominated by Poaceae, Cyperaceae, Lycopodiaceae, and Empetrum pollen. Small charcoal particles, likely transported from a distance, were found at low frequencies until 6.4 cal ka BP. The total cross-sectional area of charcoal particles increased to 1500 μm2 or more by 6.4 cal ka BP, implying that the large charcoal particles originated from nearby Aleut settlements, which were established around the same time.

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Age models and tephrostratigraphy from two lakes on Adak Island, Alaska

Cited by 13 publications

References 21 publications

The effect of species on lacustrine δ¹⁸ O_diatom and its implications for palaeoenvironmental reconstructions

The effect of species on lacustrine δ¹⁸ O_diatom and its implications for palaeoenvironmental reconstructions

Holocene atmospheric circulation in the central North Pacific: A new terrestrial diatom and δ18O dataset from the Aleutian Islands

Vegetation Changes around Haven Lake, Adak Island, Central Aleutians, Alaska, Determined from Pollen Analysis

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Age models and tephrostratigraphy from two lakes on Adak Island, Alaska

Cited by 13 publications

References 21 publications

The effect of species on lacustrine δ18 Odiatom and its implications for palaeoenvironmental reconstructions

The effect of species on lacustrine δ18 Odiatom and its implications for palaeoenvironmental reconstructions

Holocene atmospheric circulation in the central North Pacific: A new terrestrial diatom and δ18O dataset from the Aleutian Islands

Vegetation Changes around Haven Lake, Adak Island, Central Aleutians, Alaska, Determined from Pollen Analysis

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The effect of species on lacustrine δ¹⁸ O_diatom and its implications for palaeoenvironmental reconstructions

The effect of species on lacustrine δ¹⁸ O_diatom and its implications for palaeoenvironmental reconstructions