9614501 Stanley The principal focus and goal of this project is to study the evolution of Triassic and Jurassic reefs and the evolution of reef faunas in displaced terranes of western North America. A secondary goal concerns holdover faunas and possible roles of terrane faunas in reef recoveries in the Tethys. Corals, sponges and problematica are the principal reef organisms which evolved after major mass extinctions now widely recognized in the Tethys. Most reef deposits of the Cordillera have been destroyed by dynamic tectonic processes of terrane formation and accretion. However new research has uncovered a dozen key sites where preservation is sufficient to permit detailed study. This three-year project will concentrate on faunas from these sites. The terrane faunas to be investigated occur in volcanic sequences interpreted to have been ancient volcanic islands geographically remote from the Tethys. Extensive studies of early Mesozoic reef faunas of the Tethys have failed to confirm the presence of holdover taxa. However the situation in the Americas has not been fully examined. The project combines field, laboratory and museum studies of early Mesozoic sites in western North America and comparisons with Tethyan reefs to assess the idea that reef taxa in terranes played an important role in reef evolution. Documentation of biostratigraphically important microfossils, particularly conodonts, is an important element of the project. This topic will be investigated with a post-doctoral research associate who will retrieve and study conodonts and other microfossils from reef sites and use the resulting biostratigraphic data to improve the accuracy of dating and time-stratigraphic comparisons with the Tethys. Preliminary collections of reef fossils made by field geologists in Canada have revealed reef faunas containing possible Permian and Triassic holdover taxa--genera and species previously thought extinct in the Tethys following the devastating mass extinctions affecting th at region. In addition to confirming the "Lazarus effect", these discoveries, confined exclusively to western Pacific terranes, hint at the idea that terranes functioned as refuges for preferential survival of Permian and Triassic Tethyan reef taxa. The idea of volcanic islands as refuges is firmly implanted in the literature, but it is mostly speculative and largely without solid field and taxonomic base. This project therefore seeks to gather new data which, when combined with a voluminous Tethyan database now available, offers a concrete basis to assess ideas of survival and the recoveries of reef ecosystems outside the Tethys. It is possible that early Mesozoic reef faunas from volcanic terranes contain a paleontoligical record not represented in the Tethys. Careful taxonomic and field study of Triassic and Jurassic reef faunas from specific horizons, combined with graphic plotting of age and paleogeographic distributions of Tethyan and non-Tethyan taxa, will be important in confirming or refuting the idea. The resulting new data is certain to expand knowledge of reef evolution outside the Tethys, adding a stronger basis for comparisons with Tethyan faunas.
