Department Colloquium Series


Monday, September 11, 2017, 12:00pm


Haller Hall (Geological Museum, room 102)

Speaker: Associate Professor Rebecca Flowers from University of Colorado

Title: "Cratonic surface histories, kimberlites, and mantle dynamics".

Abstract: Elevation change in continental interiors is both difficult to constrain and not easily accounted for by plate margin tectonism. Dynamic topography provides an attractive explanation for these vertical motions. However, despite the increasing sophistication of dynamic models, it remains challenging to definitively test model predictions. In this talk I will summarize our work in two different cratonic regions that addresses these problems. First, I will describe our integration of low temperature thermochronology with geologic information to decipher the thickness, spatial extent, and evolution of missing sections of the Phanerozoic stratigraphic record across the North American cratonic interior. This region was shielded from distal tectonism during the Phanerozoic, making it an excellent location to isolate the effects of dynamic topography in the rock record. Our results help illuminate the cryptic hypsometric evolution of the North American continent and its potential dynamic causes. They also reveal an intriguing relationship between cratonic burial phases and gaps in the kimberlite record for which we consider possible explanations. Second, I will outline the key outcomes of our work across the Kaapvaal craton and surrounding Proterozoic terranes of the southern African Plateau. This region is widely cited as an example of dynamically supported continental topography, but also has a complex lithospheric architecture that was variably heated, thinned, and metasomatized in the Cretaceous. Our studies couple (U-Th)/He dating of kimberlites with the shallow and deep xenolith records in the pipes to decipher erosion patterns, determine their relationships with lithospheric modification effects, and better isolate lithospheric versus dynamic influences on the plateau’s topographic history. [Background Reading]