Publication Date:
2023-07-10
Description:
In this study, we use a combined biomarker and macrofossil approach to reconstruct the Holocene climate history recorded in Trifna Sø, Skallingen area, eastern North Greenland. Chronological information is derived from comparison of lithological, biogeochemical and macrofossil characteristics with a well‐dated record from nearby Lille Sneha Sø. Following local deglaciation around c. 8 cal. ka BP, the local peak warmth occurred between c. 7.4 and 6.2 cal. ka BP as indicated by maximum macrofossil abundances of warmth‐demanding plants (Salix arctica and Dryas integrifolia) and invertebrates (Daphnia pulex and Chironomidae). Warm conditions were dominated by terrestrial organic matter (OM) sedimentation as implied by the alkane‐based Paq ratio, but increased aquatic productivity is indicated when temperature was highest around 6.5 cal. ka BP. The n‐C29/n‐C31 alkane ratio shows that vegetation in the catchment was dominated by shrubs after deglaciation, but shifted towards relatively more grassy/herbaceous vegetation during peak warmth. After 5.4 cal. ka BP, the disappearance of warmth‐demanding plant and invertebrate macrofossils indicates cooling in the Skallingen area. This cooling was characterized by a significant shift towards dominance of aquatic OM sedimentation in Trifna Sø as implied by high Paq ratios. Cooling was also associated with a shift in vegetation type from dwarf‐shrub heaths towards relatively more herbaceous vegetation in the catchment, stronger erosion and more oligotrophic conditions in the lake. Our data show that mean air temperatures inferred using branched glycerol dialkyl glycerol tetraethers (brGDGTs) do not seem to accurately reflect the local climatic history. Irrespective of calibration, methylation of branched tetraethers (MBT) palaeothermometry cannot be reconciled with the macrofossil evidence and seems to be biased by either changing brGDGT sources (in situ vs. soil‐derived) or changing species assemblages and/or an unknown physiological response to changing environmental conditions at high latitude.
Keywords:
-; Acyclic glycerol dialkyl glycerol tetraether, per unit mass total organic carbon; Apatania zonella; Branched glycerol dialkyl glycerol tetraether, Ia, per unit mass total organic carbon; Branched glycerol dialkyl glycerol tetraether, Ib, per unit mass total organic carbon; Branched glycerol dialkyl glycerol tetraether, Ic, per unit mass total organic carbon; Branched glycerol dialkyl glycerol tetraether, IIa, per unit mass total organic carbon; Branched glycerol dialkyl glycerol tetraether, IIb, per unit mass total organic carbon; Branched glycerol dialkyl glycerol tetraether, IIb', per unit mass total organic carbon; Branched glycerol dialkyl glycerol tetraether, IIc, per unit mass total organic carbon; Branched glycerol dialkyl glycerol tetraether, IIc', per unit mass total organic carbon; Branched glycerol dialkyl glycerol tetraether, IIIa, per unit mass total organic carbon; Branched glycerol dialkyl glycerol tetraether, IIIa', per unit mass total organic carbon; Branched glycerol dialkyl glycerol tetraether, IIIb, per unit mass total organic carbon; Branched glycerol dialkyl glycerol tetraether, IIIb', per unit mass total organic carbon; Branched glycerol dialkyl glycerol tetraether, IIIc', per unit mass total organic carbon; Branched glycerol dialkyl glycerol tetraether, Ila', per unit mass total organic carbon; Carbon, inorganic, total; Carbon, organic, total; Cenococcum geophilum; Chironomidae; Chydorus sp.; Co1211; COMPCORE; Composite Core; Core; Crenarchaeol, per unit mass total organic carbon; Crenarchaeol isomer, per unit mass total organic carbon; Daphnia pulex group; Depth, bottom/max; DEPTH, sediment/rock; Depth, top/min; Dicyclic glycerol dialkyl glycerol tetraether, per unit mass total organic carbon; Districhium sp.; Draba sp.; Drepanocladus sp.; Dryas integrifolia; Lepidurus arcticus; Monocyclic glycerol dialkyl glycerol tetraether, per unit mass total organic carbon; n-Alkane C21, per unit mass total organic carbon; n-Alkane C22, per unit mass total organic carbon; n-Alkane C23, per unit mass total organic carbon; n-Alkane C24, per unit mass total organic carbon; n-Alkane C25, per unit mass total organic carbon; n-Alkane C26, per unit mass total organic carbon; n-Alkane C27, per unit mass total organic carbon; n-Alkane C28, per unit mass total organic carbon; n-Alkane C29, per unit mass total organic carbon; n-Alkane C30, per unit mass total organic carbon; n-Alkane C31, per unit mass total organic carbon; n-Alkane C32, per unit mass total organic carbon; n-Alkane C33, per unit mass total organic carbon; n-Alkane C34, per unit mass total organic carbon; n-Alkane C35, per unit mass total organic carbon; n-Alkane C36, per unit mass total organic carbon; n-Alkane C37, per unit mass total organic carbon; n-Alkane C38, per unit mass total organic carbon; n-fatty acid C15, per unit mass total organic carbon; n-fatty acid C16, per unit mass total organic carbon; n-fatty acid C17, per unit mass total organic carbon; n-fatty acid C18, per unit mass total organic carbon; n-fatty acid C19, per unit mass total organic carbon; n-fatty acid C20, per unit mass total organic carbon; n-fatty acid C21, per unit mass total organic carbon; n-fatty acid C22, per unit mass total organic carbon; n-fatty acid C23, per unit mass total organic carbon; n-fatty acid C24, per unit mass total organic carbon; n-fatty acid C25, per unit mass total organic carbon; n-fatty acid C26, per unit mass total organic carbon; n-fatty acid C27, per unit mass total organic carbon; n-fatty acid C28, per unit mass total organic carbon; n-fatty acid C29, per unit mass total organic carbon; n-fatty acid C30, per unit mass total organic carbon; n-fatty acid C31, per unit mass total organic carbon; n-fatty acid C32, per unit mass total organic carbon; n-fatty acid C33, per unit mass total organic carbon; Nitrogen, total; North Greenland; Nostoc sp.; Pisidium sp.; Salix arctica; Saxifraga oppositifolia; Scorpidium scorpioides; Sulfur, total; Tricyclic glycerol dialkyl glycerol tetraether, per unit mass total organic carbon
Type:
Dataset
Format:
text/tab-separated-values, 2785 data points
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