Preliminary elemental analysis of fossil insects from the Middle Jurassic of Daohugou, Inner Mongolia and its taphonomic implications

摘要

Fossil insects from the Middle Jurassic of Daohugou, Inner Mongolia were investigated using Scanning Electron Microscope (SEM) for the first time, and portions and distribution of some elements in compression and pyrited fossils were also revealed by X-ray Energy Dispersive Spectroscopy (EDS) attached to SEM. Most of compression fossil insects from the Daohugou Biota are preserved in organic remains (diagenetic products of the original organic components). A small part of compression fossils retain a comparatively high Fe concentration which probably resulted from the absorption of Fe by biopolymers during the decaying period. Pyritized insect fossils suggest that the "fossil envelop" model found in the Early Cretaceous Jehol Biota probably also occurs in the Daohugou Biota. Different preservation modes show various mechanisms of fossilization, and also suggest that several different microenvironments are present in Daohugou palaeolakes.