A preliminary study on thermoluminescence characteristics of sediments from the North Pacific

Thirty-eight surficial deposit samples were collected from the equatorial North Pacific,and the natural thermoluminescence (TL) characteristics of both bulk and clay fraction samples (<2 μm fractions) were studied by the FJ427-A1 automatic TL Dosimeter for the first time.With the measurements of clay mineral composition,element composition by XRD and ICP,the correlations between TL intensity and sedimentary environment proxies were analyzed,such as water depth,ratio of FeO to Fe₂O₃ contents,LOI,and major clay mineral concentration,and it was found the bulk sample's TL signal was stronger than the clay ones.Usually,increase in the clay components may result in the decrease of TL intensity.From the shape of TL curves,the pelagic sediments can be divided into two groups:the majority group has two glow peaks,in general,the first peak is broad and flat,but the second narrow and sharp; the minority group only has a single peak because the first is absent.The peak centers of TL curves are almost fixed,falling in the temperature sections 230~260 and 390~405℃ respectively.Lorentz model packed in the Origin 7.5 was chosen to deal with the TL curves.From the processing results,three parameters (H,C and A),corresponding to the height,center,and kurtosis of TL curve,were obtained to describe the curve characteristics.The correlations between TL curve parameters and sedimentary environment proxies were also calculated.On the basis of the above work,the relationship between TL characteristics and sediment type,mineral composition,sedimentary environment of surface sediments was discussed in the study area,and a conclusion is:sediments from the environment of shallower water,higher organic contents and weaker reductivity have stronger TL signals.