Pliocene terrace gravels of the ancestral Yukon River near Circle, Alaska: Palynology, paleobotany, paleoenvironmental reconstruction and regional correlation
Pliocene terrace gravels of the ancestral Yukon River near Circle, Alaska: Palynology, paleobotany, paleoenvironmental reconstruction and regional correlation
复制标题
阿拉斯加圆环附近祖先育空河的上新世台地砾石：孢粉学、古植物学、古环境重建和区域相关性
DOI：
10.1016/1040-6182(94)90012-4
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发表时间：
1994
影响因子：
2.2
通讯作者：
W. Yeend
中科院分区：
文献类型：
--
作者：
T. Ager;J. V. Matthews;W. Yeend
祖先育空河沉积的碎石保存在阿拉斯加中东部Circle村附近育空河谷边缘的梯田遗迹中。从这些砾石中的砂质粉砂透镜中发现的植物化石包括云杉和落叶松的球果和针叶以及各种种子。种子类型包括几个不再生长在阿拉斯加的分类群，如Epiprenum、Prunus和Weigela。从这些沉积物中发现的花粉类型代表了今天生长在阿拉斯加内陆的乔木和灌木分类群，如云杉、落叶松、桦木和Alnus，以及几个今天不再生长在阿拉斯加内陆的分类群，如松属、铁杉、刺柏和栎属。已鉴定的草本植物的花粉包括禾本科、莎草科、石竹科、菊科、Polemonium和Epilobium。Circle附近砾石中的化石植物群相似，可能年龄相当于从阿拉斯加山脉以南250公里处的Nenana砾石中发现的植物群。本文总结的孢粉学和构造证据表明，涅纳纳砾石沉积于上新世早、中期。植物化石的存在表明，阿拉斯加东部内陆早、中期的年平均温度(MAT)可能比今天的−6.4C高7-9℃，而不是今天的6.4C。
Gravels deposited by the ancestral Yukon River are preserved in terrace remnants on the margins of the Yukon River valley near the village of Circle in east-central Alaska. Plant fossils recovered from sandy silt lenses within these gravels include cones and needles ofPiceaandLarixand a variety of seeds. Seed types include several taxa which no longer grow in Alaska, such asEpipremnum, PrunusandWeigela. Pollen types recovered from these deposits represent tree and shrub taxa that grow in interior Alaska today, such asPicea, Larix, BetulaandAlnus, as well as several taxa that no longer grow in interior Alaska today, such asPinus, Tsuga, AbiesandCorylus. Pollen of herb taxa identified include Gramineae, Cyperaceae, Caryophyllaceae, Compositae,PolemoniumandEpilobium. The fossil flora from the gravels near Circle are similar and probably age-equivalent to the flora recovered from the Nenana Gravel in the Alaska Range 250 km to the south. Palynological and tectonic evidence summarized in this paper now suggests that the Nenana Gravel was deposited during the early and middle Pliocene. The presence of plant fossils ofTsuga, Abies, Pinus, WeigelaandPrunussuggests that the mean annual temperature (MAT) of eastern interior Alaska during the early and middle Pliocene was perhaps 7–9°C warmer and less continental than today's MAT of −6.4°C.