Petrology of the Gradational Intrusive Contact Between the Packsaddle Schist and the Town Mountain Granite, Enchanted Rock State Natural Area, Llano Uplift, Central Texas
The Mesoproterozoic intrusive contact between the ~1.1 Ga anorogenic Town Mountain Granite and the ~1.3 Ga Packsaddle Schist is a gradational contact exhumed within the Llano uplift. This contact is exposed along the southeastern margin of the Enchanted Rock batholith in central Texas. Field observations, hand sample and thin section petrography, and handheld X-ray fluorescence analysis of hand samples were used to characterize the gradational nature of this contact at multiple scales. The style of gradation between the Town Mountain Granite and Packsaddle Schist varies throughout the study area, containing both injection and permeation. The complex relationships observed at the contact possibly resulted from variations in temperature conditions along the contact at different stages of the emplacement.
Enchanted Rock, Town Mountain Granite, Packsaddle Schist, Llano Uplift, contact, batholith, Geology
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