The geologic record contains many past instances of biological crises linked to environmental change. These events can be thought of as past experiments that offer a window into understanding the dynamics of the current and future Earth surface system. The Oceanic Anoxic Events, or OAEs, of the Mesozoic Era (252 to 65 million years ago) are particularly relevant examples to the present changes on Earth. These intervals are notable because they are characterized by widespread marine anoxia and extinction events. OAEs also occur during times of rapid global warming and large disturbances to the global carbon cycle, thought to be associated with increased levels of greenhouse gases.
The target of this investigation is the oldest of the Mesozoic OAEs -- the Toarcian OAE of the Early Jurassic (approximately 183 million years ago). Past studies of this event have identified major disturbances to the global carbon and sulfur cycles and the occurrence of widespread marine anoxia. However, to date, the majority of these Toarcian OAE studies come from a relatively confined geographical area in Europe. The incomplete Toarcian geochemical record has led to active debates regarding the global nature of both the changes in the element cycles and the geographic extent of marine anoxia. This study will investigate both the inorganic and organic geochemical record of the Toarcian OAE in North American black shales and carbonates to assess the global-versus-regional nature of the event. Further, these new data will be integrated with the available data from Europe in a comprehensive modeling approach that will test the hypothesized mechanisms that triggered, maintained and terminated this event.
This study will have three main broader impact contributions. The first will be the development of graduate students and early career scientists at Virginia Tech and the University of Tulsa. The second will be the development of an educational program through the Museum of Geosciences at Virginia Tech aimed to inform the public about past environmental change on Earth. The Museum of Geosciences offers one of only a few public science venues in the region, and it provides an excellent venue for reaching portions of the population that would not normally be exposed to this science. The last contribution will be the mentorship of undergraduate researchers through the Tulsa Undergraduate Research Challenge (TURC). This program specializes in facilitating research for undergraduate students and community outreach.
