A quantitative study of deformation mechanisms and finite strain in quartzites
A quantitative study of deformation mechanisms and finite strain in quartzites
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石英岩变形机制和有限应变的定量研究
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发表时间：
1976
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通讯作者：
S. Mitra
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文献类型：
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作者：
S. Mitra
摘要马里兰州蓝岭的韦弗顿石英岩是由一个主要的绿片岩级变形时期变形的。测量了这些岩石的有限应变分量，这些分量是由不同的独立机制引起的。总应变分为两个主要部分：
$$vareps ^t = vareps ^p + vareps ^d .$$
利用石英晶体内部良好的应变标记--折叠和拉伸的金红石针状体，通过一种新的技术测量了位错蠕变引起的有限自然应变。压溶应变（CVP）是根据新晶体和纤维的面积与主截面中整个岩石面积的比率来测量的。晶界滑动是一个独立的过程，伴随着这两种机制。压力溶液服从线性牛顿流动定律，
$$left| {dot gamma _0^p }
ight| = A_p左| { Au _0 }
ight| $$
，而位错蠕变服从幂律形式
$$left| {dot gamma _0^d }
ight| = A_d左| { Au _0 }
ight|联系我们
哪里
$$dot gamma _0^p，dot gamma _0^d $$
为八面体剪应变率，τ0为八面体剪应力，Ap、Ap和n为常数。有限应变测量值和工作流动定律之间可以建立一个直接的关系。应用这些方法和原理到几个现场实例表明，岩石服从流动定律部分地由每个机制。任何一组物理条件都定义了一个唯一的流动定律，并且随着应变速率的增加，蠕变行为从牛顿为主转变为幂律。
AbstractThe Weverton quartzites in the Maryland Blue Ridge are deformed by one major period of greenschist-grade deformation. The components of finite strain due to different independent mechanisms have been measured for these rocks. The total strain is split up into two major components:
$$varepsilon ^t = varepsilon ^p + varepsilon ^d .$$
The finite natural strain caused by dislocation creep (ɛd) is measured by a new technique using folded and stretched rutile needles which are good strain markers within the quartz crystals. Pressure solution strain (ɛp) is measured from the ratio of the area of new crystals and fibers to the whole rock area in principal sections. Grain boundary sliding is a dependent process which accompanies both mechanisms. Pressure solution obeys a linear Newtonian flow law,
$$left| {dot gamma _0^p }
ight| = A_p left| { au _0 }
ight|$$
, while dislocation creep obeys a power law of the form
$$left| {dot gamma _0^d }
ight| = A_d left| { au _0 }
ight|^n $$
where
$$dot gamma _0^p ,dot gamma _0^d $$
are octahedral shear strain rates, τ0 is the octahedral shear stress and Ap, Ap and n are constants. A direct correlation between finite strain measurements and the operating flow laws can be made. Application of these methods and principles to a few field examples indicates that the rocks obey a flow law partly governed by each mechanism. Any set of physical conditions defines a unique flow law and there is a transition in creep behavior from dominantly Newtonian to a power law with increasing strain rate.