Abstract

Recent mapping within the metamorphic core of the southern Appalachians has led to the identification of several internal basement massifs interpreted to be windows that expose parautochthonous basement beneath the main thrust sheet. One such internal massif is exposed within the Inner Piedmont of North Carolina by the Sauratown Mountain window and is overlain by a cover sequence of arkose, schist, and quartzite. Detailed examination of the primary cross-stratification types preserved within the quartzite at Pilot Mountain indicates that deposition took place in several marine environments ranging from foreshore to inner shelf. Deposits of similar origin within the Early Cambrian North American passive-margin sediments appear to thin west to east, from 80 m at the Chilhowee Group type locality at Chilhowee Mountain (300 km west-southwest of Pilot Mountain) to 40 m within the Unaka belt (150 km west of Pilot Mountain). The quartzite at Pilot Mountain is more than 45 m thick and therefore does not appear to represent a distal part of this passive-margin sequence. Alternatively, two paleotectonic interpretations seem plausible: (1) quartzites of the Sauratown Mountains window, North Carolina, represent Late Proterozoic (Tallulah Falls-Ashe Formation equivalent) deposition along a sea-floor high associated with the rifted basement terrane during the rift phase prior to the opening of Iapetus; or (2) quartzites of the Sauratown Mountains window, North Carolina, represent latest Proterozoic to Early Cambrian (Chilhowee Group time equivalent) deposition on an isolated, rifted continental fragment during the drift phase of the North American-Iapetus margin evolution.

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