Ranking welding intensity in pyroclastic deposits
Ranking welding intensity in pyroclastic deposits
复制标题
火山碎屑沉积物中焊接强度的排名
DOI：
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发表时间：
2005
期刊：
影响因子：
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通讯作者：
J. Russell
中科院分区：
文献类型：
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作者：
S. Quane;J. Russell
火山碎屑沉积物的焊接涉及在高于玻璃化转变温度的温度下在压缩载荷下使玻璃质火山碎屑变平。渐进焊接通过岩相学的变化来记录（例如，织物）和物理（例如，密度）性质。绘制焊接强度图对于火山碎屑沉积物的研究是不可或缺的，但是在沉积物之间进行系统的比较可能是有问题的。在这里，我们开发了一个基于岩相结构观察（例如，浮石火山砾的扁率和微组构取向）和物理性质的测量，包括密度、孔隙率、点载荷强度和单轴抗压强度。我们的数据集包括从一个单一的冷却单元的Bandelier凝灰岩和平行测量8个样品的更密集的焊接存款收集的100个样品的测量。建议的分类包括六个等级的焊接强度范围从松散的（等级I）到黑曜石状玻璃斑岩（等级VI），并应允许可重复映射的焊接强度之间的细微变化不同的存款。排名方案的应用程序证明了通过使用已公布的物理性质数据焊接火山碎屑沉积物映射的总累积应变，并重建其焊接前的厚度。
Welding of pyroclastic deposits involves flattening of glassy pyroclasts under a compactional load at temperatures above the glass transition temperature. Progressive welding is recorded by changes in the petrographic (e.g., fabric) and physical (e.g., density) properties of the deposits. Mapping the intensity of welding can be integral to studies of pyroclastic deposits, but making systematic comparisons between deposits can be problematical. Here we develop a scheme for ranking welding intensity in pyroclastic deposits on the basis of petrographic textural observations (e.g., oblateness of pumice lapilli and micro-fabric orientation) and measurements of physical properties, including density, porosity, point load strength and uniaxial compressive strength. Our dataset comprises measurements on 100 samples collected from a single cooling unit of the Bandelier Tuff and parallel measurements on 8 samples of more densely welded deposits. The proposed classification comprises six ranks of welding intensity ranging from unconsolidated (Rank I) to obsidian-like vitrophyre (Rank VI) and should allow for reproducible mapping of subtle variations in welding intensity between different deposits. The application of the ranking scheme is demonstrated by using published physical property data on welded pyroclastic deposits to map the total accumulated strain and to reconstruct their pre-welding thicknesses.