石英E'心的热力学特征及其指示意义

石英EPR是一种利用矿物吸收的累积辐射能进行测年的技术方法，尽管多用于第四纪，但石英E'心在热活化后极大增强的EPR信号为拓展EPR的测年范围提供了契机.然而石英E'心的热活化条件及形成转化机理存在诸多争议.通过对花岗岩和断层带样品施加人工γ辐照，并通过步进式的阶梯退火实验，运用电子顺磁共振技术测定了不同辐射条件及温度条件下的石英E'心信号强度，探讨了石英E'心的增长和成因机理.结果表明，石英E'心可在常温常规γ辐照和高温加热2种条件下增长，并分别探讨了常温和高温E'心的测年方法及其地质意义.常温E'心的信号强度在150℃以下相对稳定，可用常规附加剂量法标定EPR信号强度以求取累积辐射能，常用于测定第四纪范围内断层的形成年龄；石英E'心在热活化后信号得到极大增强，可测定第四纪前的地质年龄，但需采用已知年龄的石英E'心热力学峰值强度作标杆或通过高剂量的γ辐照或中子辐照使氧空位再生，建立石英氧空位的剂量响应曲线以标定高温E'心代表的累积辐射能.E'心的热力学峰值通过步进式的阶梯退火实验确定，其在高温和常温时的信号强度比(I₂/I₁)具有记录辐射能和地质计时的意义. 

The Thermodynamic Characteristics of Quartz E' Center and Their Significance

The electron paramagnetic resonance of quartz is a dating technique through accumulated irradiation energy absorbed by minerals. Although it is commonly used in Quaternary period,the greatly enhanced EPR signals of quartz E' center after thermal activation provide opportunity for extending the dating range of EPR,while there are many different opinions on the thermal activation physical conditions and the formation and transformation mechanism of quartz E' center. In this paper,through the artificial γ ray radiation and stepwise annealing experiments to the granite and fault zone samples,the quartz E' center signal intensities under different irradiation conditions and different temperatures are measured by EPR technique,and the growth and formation mechanisms of quartz E' center are studied. The results indicate that the signal intensity of quartz E' center can be enhanced by normal artificial γ ray radiation under room temperature and by high temperature heating. The dating method and geological significance of E' center at normal and high temperature is discussed separately. The signal intensity of normal E' center is relatively constant below 150℃,and can be calibrated to calculate the accumulated dose and date fault forming age within Quaternary by normal additive dose method. The signal intensity of quartz E' center can be greatly enhanced by thermal activation and can be used to date geological age before Quaternary,but the activated peak signal intensity of known age quartz E' center should be used as a benchmark or the oxygen vacancy should be regenerated by high-dose γ ray irradiation or neutron irradiation. Then,the dose response curve of oxygen vacancy in quartz can be fitted to calculate the accumulated irradiation energy represented by the high temperature E' center. The thermodynamic peak of E' center should be determined by stepped annealing experiment and its signal intensity ratio (I₂/I₁) at high temperature and room temperature has the geological significance of recording irradiation energy and geological age.