Glacial lake deltas in New England record continuous, not delayed, postglacial rebound

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• 作者：Roger LeBaron Hooke^a ; ^{rogerhooke@gmail.com" class="auth_mail" title="E-mail the corresponding author} ; John Charles Ridge^b
• 关键词：Lake Hitchcock ; Delayed rebound ; Crustal flexure ; Glacial isostasy ; Late Wisconsinan
• 刊名：Quaternary Research
• 出版年：2016
• 出版时间：May 2016
• 年：2016
• 卷：85
• 期：3
• 页码：399-408
• 全文大小：2964 K

文摘

Deltas formed in Lake Hitchcock, a glacial lake that developed in the Connecticut River Valley, New England, between ∼18.3 and 12.5 ka. The heights of topset/foreset contacts of these deltas presently increase northward, linearly, at rate of ∼0.9 m/km. Others have interpreted this as indicating that isostatic rebound did not begin until after the lake drained, several kiloyears after glacial retreat began. However, (non-elastic) adjustment of Earth's lithosphere to changing loads is known to occur on time scales of years. Late-glacial shoreline features elsewhere in New England also increase in elevation with distance from the LGM margin at ∼0.9 m/km, suggesting that this is a result of fundamental properties of the crust and mantle, and independent of the history of glacier retreat. On the basis of a numerical model of flexure of the lithosphere beneath a circular load, we suggest that deflection of the lithosphere is remarkably linear in a zone 50–200 km wide between the retreating ice margin and a forebulge, and that initial rebound of this zone is spatially quite uniform for some kiloyears before differential rebound starts. Thus, lake shorelines, formed over a period of some centuries during deglaciation would, today, rise linearly northward.