美国科罗拉多大学Suzanne P. Anderson团队揭示了徘徊在摇摇欲坠的冰壁下：全新世岩石冰川的起源。2025年5月15日出版的《地质学》杂志发表了这项成果。

岩石冰川可能看起来是粗壮的、缓慢移动的、被碎片覆盖的冰川，但对它们的形成、大小和持久性的控制与冰川不同。岩石冰川的决定性特征是有足够厚的碎屑覆盖，以保护其冰芯免受消融。

因此，研究组建立了控制碎片厚度的模型，将碎片输入、冰积累和冰速结合起来。该研究组表明，岩石冰川存在于狭窄的条件范围内，这些条件提供了来自侵蚀顶壁的足够的碎片和来自焦点雪崩的足够的冰，以形成小面积的净堆积。富冰岩冰川岩心的变形速度决定了保护层积累的时间。在数量上，只有在雪崩带出口的岩石冰川表面速度为1 m/年时，以1 mm/年的速度，100 m高的顶壁背磨才能产生足够厚的碎屑覆盖。

这种低速反过来又限制了岩石冰川的长度。在地表年龄受到限制的地方，岩石冰川被发现起源于全新世早期。在全新世，岩石冰川裂片只能移动这么远，通常是几百米，很少超过一公里。高山峡谷从冰川占领到岩石冰川占领的过渡可能需要在岩石冰川条件满足之前完全消冰。最后，所需的井壁快速后退速度远远超过峰顶的垂直下降速度，这可以解释观察到的强烈的脊线不对称。

附：英文原文

Title: Lingering beneath crumbling walls: The origin of Holocene rock glaciers

Author: Robert S. Anderson, Suzanne P. Anderson

Issue&Volume: 2025-05-15

Abstract: Rock glaciers may appear to be stubby, slow-moving, debris-mantled cousins of glaciers, yet the controls on their formation, size, and persistence differ from those of glaciers. The defining rock glacier characteristic is a debris cover sufficiently thick to protect its icy core from ablation. We therefore model the controls on debris thickness, incorporating debris input, ice accumulation, and ice speed. We show that rock glaciers exist in a narrow range of conditions that provides both enough debris from eroding headwalls and enough ice from focused snow avalanches to create a small area of net accumulation. The deformation speed of the ice-rich rock glacier core sets the time available for accumulation of the protective cover. Quantitatively, a 100-m-tall headwall backwearing at 1 mm/yr produces a thick-enough debris cover only if rock glacier surface speeds at the exit of the avalanche zone are <1 m/yr. This low speed in turn limits the length of rock glaciers. Where surface ages have been constrained, rock glaciers are found to have originated in the early Holocene. There is only so far, typically hundreds of meters, rarely more than a kilometer, that rock glacier lobes can travel in the Holocene. The handover from glacial to rock glacial occupation of alpine valleys may involve complete deglaciation before rock glacier conditions are met. Finally, that the required rapid headwall retreat far outpaces vertical lowering rates of summits can explain observed strong ridgeline asymmetry.

DOI: 10.1130/G53180.1

Source: https://pubs.geoscienceworld.org/gsa/geology/article/doi/10.1130/G53180.1/654346/Lingering-beneath-crumbling-walls-The-origin-of