Taphonomic alteration of foraminifera from Quaternary siliciclastic deposits in the northern Gulf of California will be quantified through field and laboratory studies of test resistance to abrasion, dissolution, bioerosion, and transport. The close juxtaposition of Holocene and Pleistocene deposits will allow the evaluation of those processes involved in the transformation from living foraminiferal biotas through near-surface sediment assemblages to preserved fossil assemblages. The benefits from such an approach include: 1) The identification of test morphotypes which predominate within assemblages accumulating under particular environmental regimes. 2) Testing of the preservability of taphonomic signatures. 3) When combined with data on the relative abundances of living species and test production rates, the determination of the relative contributions of population dynamics and taphonomic processes to the formation of sediment assemblages. 4)The determination of test characteristics which confer resistance to destruction has important evolutionary implications and should lead to the better understanding of the morphological constraints on inhabiting particular environments. The above information will be integrated with that obtained previously from Holocene carbonate environments at Jamaica, resulting in the development of broadly encompassing taphofacies models for microfossil assemblages. As these models are based upon test morphotypes, rather than particular species, they should be applicable to numerous environments and time intervals.
