AGE OF THE WALDEN CREEK GROUP, WESTERN BLUE RIDGE PROVINCE: RESOLVING A DECADES-OLD CONTROVERSY VIA DETRITAL MINERAL GEOCHRONOLOGY AND SEDIMENTARY PROVENANCE ANALYSIS
Year of Publication
Master of Science (MS)
Arts and Sciences
Earth and Environmental Sciences (Geology)
Dr. David Moecher
Originally mapped as Precambrian and uppermost Ocoee Supergroup (OS), recent discoveries of Paleozoic microfossils have placed the Walden Creek Group (WCG), eastern Tennessee, into a younger depositional framework (Silurian or younger). In this study, monazite geochronology using SIMs, detrital zircon U-Pb geochronology determined by LA-ICP-MS, feldspar compositions determined by microprobe, zircon-tourmaline-rutile (ZTR) indices, and framework mineral modes were used to characterize provenance of sandstones of the WCG. Monazite ages cluster at 450 and 1050 Ma. All Ordovician ages are from grains that, in BSE images, have inclusion-rich microtextures interpreted as diagenetic and/or metamorphic, thus requiring that the WCG was deposited prior to Taconic metamorphism. The WCG heavy mineral suite is similar to the OS in its low modal abundance of monazite, but contains a slightly higher ZTR index. WCG Feldspar compositions are sodium poor-Kfs and sodic plagioclase, like the OS. Detrital zircon U-Pb ages for three formations of the WCG (seven samples total, n = 620) match the Ocoee signature. The dominant age modes are at ca. 1000 and 1150 Ma, with smaller modes at 1450 and 650 Ma. The monazite ages and supporting observations prove the WCG is not Paleozoic and its source rock signature matches the underlying OS.
Kelly, Evan A., "AGE OF THE WALDEN CREEK GROUP, WESTERN BLUE RIDGE PROVINCE: RESOLVING A DECADES-OLD CONTROVERSY VIA DETRITAL MINERAL GEOCHRONOLOGY AND SEDIMENTARY PROVENANCE ANALYSIS" (2014). Theses and Dissertations--Earth and Environmental Sciences. 20.