Constructing a Model of the Deep Structure of the Appalachians (2014)

Undergraduate: Sam Dawson

Faculty Advisor: Kevin Stewart
Department: Geology

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Previous tomography in the southern Appalachians by Wagner et al. (2012) reveals a deviation in the expected Mohorovicic discontinuity, raising questions of what material is convoluting the crust-mantle boundary. The work presented here seeks to resolve the two models presented in that paper through gravity modelling along two transects in the same area. The Bouguer gravity anomaly for the surrounding eight states was tested against surficial geology, elevation, and crustal thickness to test if any of these variables control the anomaly. Results from the cross-sections are inconclusive, since these new gravity models can reasonably support the possibility of a dense eclogite root at 40 to 60km depth or a homogenous mantle. However, in all models, a sharp increase in overall crustal thickness seems to be required underneath the valley and ridge province of the southern Appalachians. This thickening can be attributed to one of the three orogenies that built this mountain belt, but the presence of an extensive eclogite slab cannot be proven with gravity modelling.