ABSTRACT The known post-glacial isostatic land rise rates at Fårö Island, Central Baltic Sea, allowed for the reliable estimation of frost weathering rates of limestone clasts along five beach profiles. Weathering rates measured by clast dimension change were quantified over periods ranging between 640 and 2090 years. While the deposited beach materials at each profile have varying lithostratigraphic compositions these attributes appear to have no direct influence on the long-term comminution rates. Mean clast size of initially deposited beach materials is suggested to be primarily a function of local wave energy and sourced from local rock platforms. Field observations, climate data and literature point to the beach materials in the upper 10–20 cm being fractured under an active diurnal to short-term frost environment that has persisted over the past 1000–2000 years. Pore water freezing by 9% volumetric expansion and the development of pore water expulsion and hydrofracture is suggested to increase pore volume and pore interconnectedness over time and facilitate ice segregation growth. Observed modes of clast fracture, bursting, flaking and granular disaggregation suggest different frost weathering mechanisms to operate on different limestone lithologies. Long term rates of break down appear however not differentiated by limestone composition.

中文翻译：

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波罗的海中部法罗岛石灰岩海滩碎屑的长期霜冻风化率

摘要 波罗的海中部法罗岛已知的冰川后等静压土地上升率可以可靠地估计沿五个海滩剖面的石灰岩碎屑的霜冻风化率。通过碎屑尺寸变化测量的风化率在 640 至 2090 年之间进行量化。虽然每个剖面的沉积海滩材料具有不同的岩石地层成分，但这些属性似乎对长期粉碎率没有直接影响。最初沉积的海滩材料的平均碎屑大小被认为主要是当地波浪能的函数，并且来自当地的岩石平台。实地观察，气候数据和文献指出，在过去 1000-2000 年持续存在的活跃的昼夜到短期的霜冻环境下，上部 10-20 厘米的海滩物质发生断裂。建议通过 9% 的体积膨胀冻结孔隙水以及发展孔隙水排出和水力压裂，以随着时间的推移增加孔隙体积和孔隙互连性，并促进冰离析增长。观察到的碎屑断裂、爆裂、剥落和颗粒解聚模式表明，不同的霜风化机制在不同的石灰岩岩性上起作用。然而，长期分解率似乎并没有因石灰石成分而异。建议通过 9% 的体积膨胀冻结孔隙水以及发展孔隙水排出和水力压裂，以随着时间的推移增加孔隙体积和孔隙互连性，并促进冰离析增长。观察到的碎屑断裂、爆裂、剥落和颗粒解聚模式表明，不同的霜风化机制在不同的石灰岩岩性上起作用。然而，长期分解率似乎并没有因石灰石成分而异。建议通过 9% 的体积膨胀冻结孔隙水以及发展孔隙水排出和水力压裂，以随着时间的推移增加孔隙体积和孔隙互连性，并促进冰离析增长。观察到的碎屑断裂、爆裂、剥落和颗粒解聚模式表明，不同的霜风化机制在不同的石灰岩岩性上起作用。然而，长期分解率似乎并没有因石灰石成分而异。