History and dynamics of the Greater Yellowstone Glacial System during the last two glaciations

QUATERNARY SCIENCE REVIEWS

卷:200

Review

Licciardi, Joseph M.¹  Pierce, Kenneth L.² 

[1] Univ New Hampshire, Dept Earth Sci, 56 Coll Rd, Durham, NH 03824 USA

[2] US Geol Survey, NRMSC, 2327 Univ Way,Box 2, Bozeman, MT 59715 USA

关键词: Pleistocene;    Glaciation;    Paleoclimatology;    North America;    Cosmogenic isotopes;    Geomorphology;    Orographic precipitation;    Glacial;    Yellowstone;    Teton Range;    Pinedale;    Bull Lake;   

DOI  :  10.1016/j.quascirev.2018.08.027

来源: Elsevier

【 摘 要 】

The Greater Yellowstone Glacial System (GYGS) covered about 20,000 km(2) at its maximum Pleistocene extent. The initiation, culmination, and ultimate decay of the GYGS involved complex interactions between several coalescent ice masses flowing from glacial source areas adjoining and including the Yellowstone Plateau. Here, we present an updated review of the history and dynamics of the GYGS during the penultimate (Bull Lake) and last (Pinedale) glaciations, drawing upon an integration of glacial geologic mapping with >130 cosmogenic Be-10 and He-3 exposure ages. Bull lake glacial deposits in greater Yellowstone are dated to ca. 150-140 ka and correlate with marine isotope stage 6. The Bull lake glaciation extended well beyond the Pinedale along the southern and western GYGS margins, but Pinedale glaciers overrode Bull Lake ice limits on the north and east sides. The northeastward shift of the center of ice mass from Bull lake to Pinedale time may be explained by uplift on the leading edge of the Yellowstone hotspot and subsidence on the trailing margin. In early Pinedale time (similar to 22-18 ka), ice buildup culminated in the high terrain of the Beartooth Uplift and High Absaroka Range. Glaciers from these source regions flowed onto the northeastern margin of the Yellowstone Plateau and advanced to terminal moraines beyond Clarks Fork Canyon and in Jackson Hole. By middle Pinedale time (similar to 18-16 ka), the Yellowstone Plateau ice cap surface had risen above the equilibrium-line altitude, stimulating orographic glacial buildup nourished by storms funneled eastward through the Snake River Plain. The plateau ice cap eventually thickened to >1000 m and joined glaciers from the Beartooth Uplift and Gallatin Range to form the northern Yellowstone outlet glacier. Terrain east and downwind of the ice cap crest was placed in a precipitation shadow, resulting in glacial recession in these regions. During the late Pinedale (similar to 16-13 ka), the plateau ice cap prograded southwestward toward the direction of moisture supply, leading to advances along the southern and western margins of the GYGS. Northern sectors of the plateau ice cap were nearly stagnant at this time. The Yellowstone region experienced widespread deglaciation ca. 15-14 ka in response to warming climate. Unloading of the -1 km-thick plateau ice cap and consequent release of pressure on the magmatic system beneath Yellowstone was not accompanied by volcanism, indicating that the magma chamber was not primed to erupt via decompression during the last deglaciation. (C) 2018 Elsevier Ltd. All rights reserved.

【 授权许可】

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