Calcite fabrics, growth mechanisms, and environments of formation in speleothems from the Italian Alps and southwestern Ireland
Calcite fabrics, growth mechanisms, and environments of formation in speleothems from the Italian Alps and southwestern Ireland
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DOI：
10.1306/022900701183
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发表时间：
2000-09-01
影响因子：
2
通讯作者：
McDermott, F
中科院分区：
文献类型：
--
作者：
Frisia, S;Borsato, A;McDermott, F
根据形态学和显微结构特征，在阿尔卑斯和爱尔兰洞穴中鉴定出5种织物，它们与生长机制和生长环境有关。柱状和纤维状织物在洞穴中持续湿润，在接近平衡条件下（低过饱和；SIcc < 0.35），通过螺位错机制生长。高度缺陷的微晶织物与柱状织物在相同的过饱和范围内形成，但在不同的放电和生长抑制剂的存在下形成。枝晶结构具有最高密度的晶体缺陷，在不平衡条件下（高过饱和），在周期性的非常低流态周期下发育，导致长时间的脱气。洞穴钙质凝灰岩是在不平衡条件下形成的。只有在低过饱和度下形成的织物方解石晶体似乎沉淀出近同位素平衡条件。
Five fabrics were identified in Alpine and Irish caves on the basis of morphological and microstructural characteristics, and related to growth mechanisms and growth environment. Columnar and fibrous fabrics grow when speleothems are continuously wet, and from fluids at near equilibrium conditions (low supersaturation; SIcc < 0.35), through the screw dislocation mechanism. The highly defective microcrystalline fabrics form at the same supersaturation range as columnar fabric but under variable discharge and the presence of growth inhibitors. Dendritic fabrics, which have the highest density of crystal defects, develop in disequilibrium conditions (high supersaturation) under periodic very low-flow-regime periods that result in prolonged outgassing. Cave calcareous tufa forms in disequilibrium conditions. Only the calcite crystals of fabrics formed at low supersaturation seem to precipitate near-isotopic-equilibrium conditions.