Taphonomy and Quality of the Fossil Record

Abstract

The reliability of microfossils in stratigraphic and paleoenvironmental interpretation depends on how accurately the microfossil assemblage corresponds to the live community. The organisms after death undergo a complex transition from biosphere to lithosphere. The decay of the organic matter, post-mortem transport of the shells and their dissolution and diagenesis prior to and after burial under sediments determine the fidelity of the fossil records. The early taphonomic processes may cause preferential loss of some microfossils and post-mortem transport may move shells out of their original habitat with far-reaching implications for reconstruction of the past environment. Chemical susceptibility to diagenesis and dissolution may cause marked changes in trace elements and the stable isotope composition of the shells and, thus, limit the use of compositional data in paleoenvironmental and paleoclimatic interpretations. The fossil assemblages are time-averaged due to transport, dissolution, bioturbation and reworking. Moreover, sedimentation may be continuous to intermittent, and the rate of sedimentation may vary widely in different depositional settings. Taphonomy and sedimentation, thus, contribute to the resolution of a stratigraphic section. The chemical reactions of decay, traction velocities of shells, resolution analysis and mathematical model of bioturbation are discussed to develop an understanding of the microfossil records.