Soft sediment deformation structures are common in fine-grained pyroclastic deposits and are often taken, along with other characteristics, to indicate that deposits were emplaced in a wet and cohesive state. At Ubehebe Crater (Death Valley, California, USA), deposits were emplaced by multiple explosions, both directly from pyroclastic surges and by rapid remobilization of fresh, fine-ash-rich deposits off steep slopes as local granular flows. With the exception of the soft sediment deformation structures themselves, there is no evidence of wet deposition. We conclude that deformation was a result of destabilization of fresh, fine-grained deposits with elevated pore-gas pressure and dry cohesive forces. Soft sediment deformation alone is not sufficient to determine whether parent pyroclastic surges contained liquid water and caused wet deposition of strata.

中文翻译：

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加利福尼亚死亡谷Ubehebe Crater干热碎屑沉积物中的软沉积物变形

软质沉积物变形结构在细粒火山碎屑沉积物中很常见，并经常与其他特征一起用来表明沉积物以湿润和凝聚态存在。在Ubehebe Crater（美国加利福尼亚死亡谷），沉积物是由多次爆炸引起的，既有火山碎屑潮直接引起的，也有来自局部陡坡的新鲜，细灰分丰富的新鲜沉积物的快速迁移，这些沉积物是局部颗粒状流动。除了软的沉积物变形结构本身外，没有湿沉降的迹象。我们得出的结论是，变形是由于新鲜的，细颗粒的沉积物的不稳定而导致的，该沉积物具有增加的孔隙气压和干凝聚力。