微环境对流纹岩风化速度的影响

INFLUENCE OF MICROENVIRONMENT ON RHYOLITE WEATHERING RATE

通过对位于浙江省衢州市南宗孔氏家庙中2个建造于1520年的流纹岩灯台的风化进行研究,不仅得出流纹岩在潮湿环境下的风化速度为0.4～9.7mm/(100a),而且发现不同灯台之间、同一灯台的不同部位之间以及同一灯台同一部位不同朝向之间的风化速度都有较大的差异。如:(1)灯台1和2上圆盘上表面朝北向的风化速度分别为4.3和9.7mm/(100a),大于朝南向的风化速度,分别为基点(即未风化点)和2.1mm/(100a);而下圆鼓则恰恰相反:灯台1朝西南向和灯台2朝南向的风化速度则是其下圆鼓中最大的(分别为3.08和2.05mm/(100a))。据分析,造成这种差异的原因是灯台所处的微环境(如风、降水、太阳辐射等)的不同。(2)与其他部位相比,两灯台上圆盘插烛孔的风化速度最小,其最大值为1.0mm/(100a)。这可能是因为插烛孔内常年积水而隔绝空气所致,可以通过采取改善石灯台风化环境的措施对其进行长期保护。

Through studying of weathering of two rhyolite light stands built in 1520 AD in Confucius Temple of Quzhou, Zhejiang province, their weathering rates in moist environment are elicited （0.4 - 9.7 mm/（100 a））, and the differences between light stands, different parts of one light stand, and the same part in different aspects are also discovered. For examples, （1） The weathering rates of the top disks in north aspect of No.1 and No.2 light stands are 4.3 and 9.7 mm/（100 a）, which are larger than these in south aspect（datum mark and 2.1 mm/（100 a））. But that are quite different in the bottom, the weathering rates in southwest aspect of light stand No. 1 and in south aspect of No.2 are the largest in the bottom, which are 3.1 and 2.1 mm/（100 a）, respectively. Such differences are caused by the microenvironment like wind, rainfall, solar radiation and so on. （2） Compared with other part of the light stands, the weathering rates of candle holes in top disks are the smallest, which are no more than 1.0 mm/（100 a）, because they are isolated from air for always filled with water （mostly are rainfall）. From the above, a basic idea is proposed to obstruct factors that influenced weathering for long-term protection of the light stands.