| Popis: |
With increasing temperatures, microscopic fish remains (called ichthyoliths) undergo significant color alterations and therefore may be useful in determining the paleotemperature histories of sedimentary rock sequences. For this preliminary study, ichthyoliths were heated in open air and their resultant colors recorded and compared to other standards such as conodont color alteration and vitrinite reflectance values. Although ichthyoliths undergo significant changes in color when exposed to thermal gradients, these colors are highly variable in the majority of dentinal tissues observed, and preclude a simple correlation between color and the degree of thermal alteration. In addition, the porosity of ichthyoliths makes them highly susceptible to other factors (e.g. permineralization) which can alter their color and imply thermal alteration where none has occurred. Based on these initial experiments, it appears that the denser fish material is more likely to be useful in carbonization studies and that, because of the porosity of fish remains, open-air heating experiments are not appropriate tests of thermal maturation of ichthyoliths as they are with conodonts. INTRODUCTION |
