Using a mathematical model of a weathering clast to explore the effects of curvature on weathering
Using a mathematical model of a weathering clast to explore the effects of curvature on weathering
复制标题
利用风化碎屑的数学模型探讨曲率对风化的影响
DOI：
10.1016/j.chemgeo.2015.03.027
复制
发表时间：
2015
期刊：
影响因子：
3.9
通讯作者：
Brantley, S.L.
中科院分区：
文献类型：
--
作者：
Lebedeva, M.I.;Sak, P.B.;Ma, L.;Brantley, S.L.
首次，我们表明，外壳厚度的表面上开发的碎屑具有不同的曲率值可以用来估计碎屑风化的持续时间。为了得到任意形状碎屑上曲线型风化锋速度的解析表达式，我们对多矿物反应扩散模型进行了近似，并对简化的二维模型进行了数值分析.分析表明，随着风化锋曲率的增加，风化进程的数学描述与平流作为主要溶质运移机制的数学描述是等价的，即使对于仅通过扩散发生传输的情况。具体地说，对于曲率K < 0、扩散率（D）和孔隙度（ε）均为常数的曲线型风化前缘，风化推进速率的法向分量可使用平流类项计算，其中平流速度v可表示为v =D ε| K|.因此，在K < 0的情况下，在沿着皮-芯界面的点处，皮厚度与芯-皮界面的曲率的绝对值成正比。反应前沿厚度也随K的增加而增加。这些推论与实地观察一致。如果已知某些参数，这种定量分析可以评估风化的持续时间。例如，利用在瓜德罗普风化的碎屑在两个位置观察到的曲率差异（0.12 mm− 1和0.018 mm− 1）和相应的外壳厚度差异（35.8 mm和20.6 mm），我们估计风化持续时间约为118 ky，这与之前通过U系列同位素不平衡确定的风化年龄一致。
For the first time, we show that rind thicknesses developed on surfaces of a clast with different values of curvature can be used to estimate the duration of clast weathering. To obtain an analytical expression for the velocity of the curvilinear weathering front on a clast of arbitrary shape, we approximate our previous multi-mineral reactive-diffusion model and explore a simplified 2-D model numerically and analytically.Our analysis documents that with increasing curvature of the weathering front, the mathematical description of weathering advance is equivalent to that derived for advection as the dominant solute transport mechanism, even for the case where transport is occurring by diffusion only. Specifically, for a curvilinear weathering front with constant curvatureK< 0, diffusivity (D), and porosity (ϕ), the normal component of the weathering advance rate can be calculated using an advection-like term where the advection velocityvcan be expressed asv=Dϕ|K|. Therefore, at points along the rind–core interface withK< 0, rind thickness is directly proportional to the absolute value of the curvature of the core–rind interface. The reaction front thickness also increases withK. These inferences are in agreement with field observations. This quantitative analysis allows an assessment of the duration of weathering if certain parameters are known. For example, using the difference in curvature observed at two positions for a clast that weathered in Guadeloupe (0.12 mm− 1and 0.018 mm− 1) and the corresponding rind thickness difference (35.8 mm and 20.6 mm), we estimated the duration of weathering to be about 118 ky, which is consistent with the weathering ages previously determined by U-series isotope disequilibrium.
登录
查看更多内容
影响因子：
1.3
作者：
S. McCue;J. King;D. Riley
通讯作者：
D. Riley
DOI：
10.1098/rspa.2002.1059
发表时间：
2003
期刊：
Proceedings of the Royal Society of London. Series A: Mathematical, Physical and Engineering Sciences
影响因子：
--
作者：
S. McCue;J. King;D. Riley
通讯作者：
D. Riley
托里登砂岩（苏格兰西北部）巨石的边缘圆度：相对年代测定的应用以及对温暖和寒冷气候风化率的影响
影响因子：
2.2
作者：
M. Kirkbride;CARA M. Bell
通讯作者：
CARA M. Bell
利用岩石风化壳厚度进行新西兰全新世绝对年龄测定
DOI：
10.1080/00040851.1981.12004224
发表时间：
1981
期刊：
Arctic and alpine research
影响因子：
--
作者：
T. Chinn
通讯作者：
T. Chinn
影响因子：
2.5
作者：
R. H. Knapp;R. Aris
通讯作者：
R. Aris