Grant: Discovery Grants Program - Individual

The Paleozoic (from 542 to 251 million years ago) was a time of extraordinary events and geologic upheaval such as the extraordinary radiation of life, extraterrestrial impacts and mass extinctions, all punctuated by both alpine and continental glaciations. The study proposes to collect proxy material (i.e. brachiopods and trilobites) and examine the geochemical evidence (trace and isotope chemistry) to characterize these events. Material for this project will come from two major sources, one being carbonates deposited on seamount Japan during the Paleozoic reflecting Panthalassic Ocean (precursor Pacific) oceanography and from large and continuous successions at the North American continental margin. The latter localities are unique and important in that the successions are sedimentologically & stratigraphically well defined in the context of Paleozoic biogeography. Construction of global seawater records will consist of material judged by a multitude of evaluation criteria to contain a pristine and primary signal; others will be discarded. These ultra-high (±10,000 y) seawater records of sea surface temperature (SST) and composition (SSC) will provide a tool for better understanding events and changes of the Earth's biologic, geologic, and hydrologic systems. Another major underpinning of this approach will be the use of the revolutionary 'clumped isotope thermometer', which allows for the direct determination of ambient seawater temperature and the subsequent computation of its oxygen isotopic composition and salinity. The Paleozoic, a time of numerous ice ages including the LPIA (Late Paleozoic Ice Age), is considered one of the largest in the geologic record as well as the one reflecting most closely the last Ice Age. Near-field evidence (of others) coupled with the far-field results will allow for better constraints as to timing, duration, extent and causes of both glaciation and de-glaciation events (greenhouse gas warming). This study period, because of the lack of an anthropogenic factor, may provide fundamental and important information for judging the human impact on the Earth's current climatic situation.