Tectonic significance of preliminary uranium-lead ages from the eastern Piedmont of North Carolina

Conference · Tue Mar 01 04:00:00 EST 1994 · Geological Society of America, Abstracts with Programs; (United States)

OSTI ID:6886605

Horton, Jr, J W; Stern, T W ^[1]

---

1. Geological Survey, Reston, VA (United States)

Preliminary uranium-lead apparent ages of zircon populations of presumed igneous origin from rocks in the eastern Piedmont of North Carolina have significant tectonic implications. A major unit in the Raleigh metamorphic belt, the Raleigh gneiss, probably is not part of the Grenville Goochland terrane as is commonly proposed. The validity of a separate Raleigh terrane (also previously proposed) is questionable, because a discordant Cambrian age for the Raleigh gneiss suggests that this unit could be an amphibolite-facies equivalent of rocks in the Spring Hope terrane. Rocks of the proposed Spring Hope and Crabtree terranes are Middle Cambrian or older and, thus, are similar to parts of the Carolina slate belt in South Carolina (the type area of the Carolina terrane). The Roanoke Rapids terrane contains Late Proterozoic rocks similar to those in the northern part of the Carolina slate belt in North Carolina and Virginia. All these proposed terranes appear to be generally Avalonian or pan-African in age. Further work is needed to test and evaluate whether they are separate volcanic-arc terranes of Avalonian/pan-African affinity or parts of a single terrane dismembered by post-accretionary faulting. Discordant zircon ages from the granitic Falls leucogneiss significantly pre-date Alleghanian deformation in the Nutbush Creek shear zone. Late Paleozoic granites having different ages within the Rolesville batholith corroborate field relations indicating that the Rolesville is a composite pluton. Late Paleozoic ages also were obtained from deformed granitoids not previously recognized as Alleghanian.

• OSTI ID: 6886605
• Report Number(s): CONF-9404221--
• Conference Information: Journal Name: Geological Society of America, Abstracts with Programs; (United States) Journal Volume: 26:4
• Country of Publication: United States
• Language: English

Related Subjects

58 GEOSCIENCES
580000* -- Geosciences
ACTINIDE ISOTOPES
AGE ESTIMATION
DEVELOPED COUNTRIES
GEOLOGIC FORMATIONS
GNEISSES
ISOTOPE DATING
ISOTOPES
METAMORPHIC ROCKS
MINERALS
NORTH AMERICA
NORTH CAROLINA
ROCKS
SILICATE MINERALS
TECTONICS
URANIUM ISOTOPES
USA
ZIRCON