A chronological framework for the Holocene vegetational history of central Minnesota: the Steel Lake pollen record
A chronological framework for the Holocene vegetational history of central Minnesota: the Steel Lake pollen record
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明尼苏达州中部全新世植被历史的年代框架：钢湖花粉记录
DOI：
10.1016/j.quascirev.2003.09.003
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发表时间：
2004
影响因子：
4
通讯作者：
F. Hu
中科院分区：
文献类型：
--
作者：
H. E. Wright;I. Stefanova;Jian Tian;T. Brown;F. Hu
明尼苏达州及邻近地区的古记录经常被用来评估北美中部大陆的大规模气候过程。然而，这些记录中的大多数都受到年代缺陷的影响，这使得与基于其他记录(例如格陵兰的GISP2)的气候解释进行任何比较都是有问题的。我们报道了明尼苏达州中部斯蒂尔湖的陆地大型化石的高分辨率孢粉记录，其可靠的年代学受2614C年代学的限制。约11.2ka BP(距今11000年)，钢湖附近的晚冰期云杉森林突然被班克松和/或松脂取代。随着草原类群的扩展，松林开始开放9.4ka calBP，松林或稀树草原占主导地位，直到8ka calBP左右，栎树取代松树成为草原地区的优势树种，持续了4500年。紧密的时间控制使得关键的植被变化可以与达科他州东部和明尼苏达州其他可靠年代地点的植被变化相关联，这表明在2000年期间，云杉林的突然衰退是从西南向东北的时间超越性的，草原的发展在2600年中是同一方向的时间超越性的。斯蒂尔湖的关键孢粉层与位于斯蒂尔湖西北约50公里处的麋鹿湖高分辨率孢粉剖面的对比表明，著名的全新世早期麋鹿湖孢粉年代学大约太年轻了1000年。
Paleorecords from Minnesota and adjacent areas have often been used to evaluate large-scale climatic processes in the mid-continent of North America. However, most of these records are compromised by chronological flaws, making problematic any comparisons with climatic interpretations based on other records (e.g., GISP2 in Greenland). We report here a high-resolution pollen record with a secure chronology constrained by 2614C dates on terrestrial macrofossils from Steel Lake, central Minnesota. About 11.2ka cal BP (11,000 calibrated yr before present) the late-glacial Picea forest near Steel Lake was succeeded abruptly by Pinus banksiana and/or resinosa. The Pinus forest began to open 9.4ka cal BP with the expansion of prairie taxa, and a pine parkland or savanna prevailed until about 8ka cal BP, when Quercus replaced Pinus to become the dominant tree in the prairie areas for 4500 yr. The close chronological control permits the correlation of key vegetational changes with those at other reliably dated sites in the eastern Dakotas and in Minnesota, suggesting that the abrupt decline of the spruce forest was time-transgressive from southwest to northeast during 2000 yr, and that the development of prairie was time-transgressive in the same direction over 2600 yr. Correlation of key pollen horizons at Steel Lake with those in the high-resolution pollen profiles of Elk Lake, ca. 50km northwest of Steel Lake, suggests that the well-known Elk Lake varve chronology for the early Holocene is about 1000 yr too young.