Last glacial maximum ecology and climate from terrestrial gastropod assemblages in Peoria loess, western Kentucky
Last glacial maximum ecology and climate from terrestrial gastropod assemblages in Peoria loess, western Kentucky
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DOI：
10.1002/jqs.3206
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发表时间：
2020-05
影响因子：
2.3
通讯作者：
D. Grimley;R. Counts;J. Conroy;Hong Wang;S. Dendy;Catherine B. Nield
中科院分区：
文献类型：
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作者：
D. Grimley;R. Counts;J. Conroy;Hong Wang;S. Dendy;Catherine B. Nield
位于肯塔基州西部无冰川作用的岩石黄土部分提供了末次盛冰期爆发期间的高分辨率环境记录。皮奥里亚淤泥（9 m 厚）包含 26 种陆生腹足动物，每 5 cm 间隔内多达 15 种。使用贝壳或木炭进行十三种放射性碳年龄，范围在 30 至 24.5 cal ka 之间；较年轻的黄土已被淋滤或侵蚀。腹足动物组合的地层变化意味着显着的变冷，特别是~27 cal ka，因为太阳辐射正在减少，而南劳伦泰冰盖正在迅速推进。中西部到南部的物种（例如 Anguispira kochi、Gastrocopta pentodon、Hawaii miniscula、Helicodiscus parallus、Vallonia perspectiva）仅出现在最底层的皮奥里亚淤泥（约 30-27 cal ka）中。相比之下，耐寒物种（Columella alticola、Vertigomodeta、Vallonia gracilicosta）仅出现在全冰川皮奥里亚淤泥（27-24.5 cal ka）中。根据共同气候范围方法推断的 7 月平均气温范围为 30 cal ka 时约 23 °C，26 cal ka 时冷却至约 18 °C；比现在低约 3–8 °C（~26 °C）。叠加在这种冷却趋势上的是碎屑碳酸盐、化石贝壳浓度、古温度估计和氧同位素值（Vertigo、Discus、Helicodiscus）的数百年变化。更精细的尺度变化意味着冰川沉积物供应、黄土沉积和气候的相对同步波动。
The Rocks loess section, in unglaciated western Kentucky, provides a high‐resolution environmental record during the last glacial maximum onset. The Peoria Silt (9 m thick) contains 26 terrestrial gastropod species, with up to 15 species within a single 5 cm interval. Thirteen radiocarbon ages, using shells or charcoal, range between 30 and 24.5 cal ka; younger loess has been leached or eroded. Stratigraphic shifts in gastropod assemblages imply significant cooling, particularly ~27 cal ka, as solar insolation was decreasing and the southern Laurentide Ice Sheet rapidly advancing. Midwestern to southern species (e.g. Anguispira kochi, Gastrocopta pentodon, Hawaii miniscula, Helicodiscus parallelus, Vallonia perspectiva) occur only in the lowermost Peoria Silt (~30–27 cal ka). In contrast, cold‐tolerant species (Columella alticola, Vertigo modesta, Vallonia gracilicosta) occur only in full glacial Peoria Silt (27–24.5 cal ka). Inferred mean July temperatures, from mutual climatic range methods, range from ~23 °C at 30 cal ka, cooling to ~18 °C by 26 cal ka; about 3–8 °C cooler than today (~26 °C). Superimposed on this cooling trend are multi‐centennial variations in detrital carbonate, fossil shell concentrations, palaeotemperature estimates, and oxygen isotope values (Vertigo, Discus, Helicodiscus). The finer‐scale variations imply relatively synchronous fluctuations in glacial sediment supply, loess sedimentation, and climate.