2000: Ecosystem response to Lateglacial and early Holocene climate oscillations in the Great Lakes region of North America
Fossil pollen, plant macrofossils, gastropods, and elemental and stable-isotope geochemistry in a sediment core from Twiss Marl Pond, southern Ontario, Canada, were used to document climate oscillations during the Last Glacial}Interglacial transition (&13,000}8500 14C BP) and understand their ec...
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| Format: | Text |
| Language: | English |
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| Online Access: | http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.525.5946 http://www.lehigh.edu/~ziy2/pubs/Yu2000QSR.pdf |
| Summary: | Fossil pollen, plant macrofossils, gastropods, and elemental and stable-isotope geochemistry in a sediment core from Twiss Marl Pond, southern Ontario, Canada, were used to document climate oscillations during the Last Glacial}Interglacial transition (&13,000}8500 14C BP) and understand their ecological e!ects. Chronology was provided by AMS 14C dating and regional pollen correlation. Oxygen isotope (d18O) results from mollusc shells, Chara-encrustations and bulk carbonates show a classic climate sequence of a warm B+lling}Aller+d (BOA) at &12,500}10,920 14C BP, a cold Younger Dryas (YD) at 10,920}10,000 14C BP, the Holocene warming at 10,000 14C BP, a brief Preboreal Oscillation (PB) at 9650 14C BP, and a possible Gerzensee/Killarney (G/K) cooling shortly before 11,000 14C BP. Clay sediments at the base of the core contain high herb and shrub pollen and abundant arctic/alpine plant macrofossils, indicating a treeless tundra with severe soil erosion in watershed. During the BOA warm period, authigenic marl began to be deposited, and Picea woodland became established. The establishment of Picea woodland after peaks of d18O and of carbonate accumulation suggests a lagged response of upland vegetation to BOA warming. In contrast, the occurrence of warmth-loving aquatics Najas yexilis and Typha latifolia at that time indicates sensitive responses of aquatic plants. The YD cooling is indicated by a &1.5 & negative excursion in d18O, an increase in minerogenic matter and higher concentrations of erosion-derived elements (Al, Na, K, Ti and V). Pollen data show no forest transformation in response to YD cooling, which is attributed to the insensitive nonecotonal vegetation at |
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