SMEAR SLIDES MADE EASIER BY A NEW ONLINE RESOURCE: TMI (TOOL FOR MICROSCOPIC IDENTIFICATION)

LacCore announces the development of an interactive web-based tool for the identification of sedimentary components in smear slide. The smear slide technique is one of limnogeology’s most powerful sources of information on past depositional environments, geochemistry, and ecology. Preparation of smear slides using tiny amounts of unconsolidated sediment is cheap, fast, and low-tech, and their analysis requires only a petrographic microscope available in most geology departments. Unfortunately, until now, no reference work has existed for lacustrine sediments (the marine sedimentary textbook is long out of print and lacks many components found only in inland waters), and so the method has remained difficult for students and researchers to learn except under the instruction of an experienced tutor.

Smear slide analysis is used to semiquantitatively determine sediment mineralogy, grain size distribution/sorting/rounding, percent and type of organic matter, diatom diversity, degree and nature of diagenesis, and other characteristics that provide the essential context for interpretation of the geochemical, biological, and chronological data that are generated from sediment subsamples. Used as a part of initial core description, smear slides can – virtually nondestructively – give a tremendous amount of paleoenvironmental information before the first analytical dollar is spent.

TMI features both a dichotomous key structure for identification of sedimentary components by the novice or in the classroom, and search and immediate drill-down interfaces that experienced analysts can use to confirm an identification. The tool includes reference images (usually several) of each sedimentary component, as well as text descriptions of distinguishing and diagnostic features. Minerals and mineraloids are TMI’s primary focus, but the tool also includes common biological components (sponge spicules, phytoliths, pollen, chitin, algal and vascular plant remains, etc.) and has an integrated link with the Diatoms of the United States website. Since lakes and oceans do share many sedimentary components, the resource will also be useful to those working with marine cores, and we welcome expansion of the database to include additional components from both continental and marine sedimentary environments.