Brightness of pollen as an indicator of thermal alteration by means of a computer-driven image processor: statistical thermal alteration index (stTAI)

The brightness, or gray level, of pollen of Pinus, Podocarptrs, Abies, Pice a and Tsuga from the Neogene sediments in northern Japan was measured using a transmitted-light microscope with a computer-driven digital image proces sor. The mean value of the modes for the complete array of the indigenous p ollen in a rock sample was caned here "the statistical thermal alteration i ndex" (stTAI). In the present investigation an inverse relationship between stTAI and vitrinite reflectance (R-O) in sediments was found. The applicat ion of stTAI to samples from three boreholes indicated a decreasing trend w ith depth. By using this trend, threshold values of intense oil generation can be evaluated (145-110). Therefore, stTAI can be a useful parameter for determining organic maturation and for identifying the threshold zone of in tense oil generation. (C) 2001 Elsevier Science Ltd. All rights reserved.