Thermodynamical behavior of E′ centers in quartz from sediments: Potential for paleothermometry and geochronometry

Abstract

The thermodynamical behaviors of E' centers in 8 quartz samples from core XJ33-2-1 recovered in the Zhujiang Mouth Basin were measured by electron spin resonance (ESR) technique. The E' ESR spectral intensity of samples before any laboratory treatment was measured and expressed as I. The samples were then annealed at 300°C or 350°C for 60 min. The E' ESR spectral intensity measured after this procedure is expressed as I 2 . The ratios of I, to 12 for the samples increase with the sample depth (from 320 to 3972 m), showing that there is a correlation between this ratio and the storage temperature of samples. Therefore the ratio of ' "2 can be used as an ESR paleothermometer. Besides the temperature, we must take into account the period of time for which the samples have been buried since their deposition, because we find that the ratios 'I"2 (from 0.293 to 0.941) are closely related to the sediment ages (from 1.5 to 27.5 Ma), with a correlation coefficient of 0.98 or 0.99 obtained by linear or exponential regression, respectively. This relation can be explained by the increase of E' center concentration in quartz samples with the sedimentation age.