Geochronologic Age Constraints on Tectonostratigraphic Units of the Central Virginia Piedmont, USA
Links
- Document: Report (9.51 MB pdf)
- Tables:
- Table 2 (98.5 KB xlsx) - Isotopic data for all analyses by laser ablation-inductively coupled plasma-mass spectrometry at the U.S. Geological Survey Central Mineral and Environmental Resources Science Center Isotope Laboratory in Denver, Colorado
- Table 3 (447 KB xlsx) - Isotopic data for all analyses by secondary ionization mass spectrometry on the U.S. Geological Survey/Stanford sensitive high-resolution ion microprobe-reverse geometry
- NGMDB Index Page: National Geologic Map Database Index Page
- Download citation as: RIS | Dublin Core
Abstract
New geologic mapping coupled with uranium-lead (U-Pb) zircon geochronology (sensitive high-resolution ion microprobe-reverse geometry [SHRIMP-RG] and laser ablation-inductively coupled plasma-mass spectrometry [LA-ICP-MS]) analyses of 10 samples, provides new constraints on the tectonostratigraphic framework of the central Virginia Piedmont. Detrital zircon analysis confirms that the Silurian-Devonian Quantico Formation is a postorogenic successor basin, with zircons derived primarily from Ordovician Chopawamsic Formation volcanic rocks. Detrital zircons from strata of the Long Island syncline, previously mapped as a separate successor basin, have a peri-Gondwanan component distinct from Laurentian-sourced rocks of the Potomac terrane to the west. Volcanism of the Chopawamsic Formation spanned at least 14 million years during the Ordovician. The Chopawamsic Formation contains sheet-like Late Ordovician-Silurian granodioritic and tonalitic intrusions that were once mapped as Carboniferous. Biotite-muscovite migmatitic paragneiss, which borders the Chopawamsic Formation on its southeast side and also occurs east of the Lakeside fault, preserves evidence of Silurian deformation and metamorphism, with a Carboniferous (Alleghanian) overprint. Limited SHRIMP-RG analysis of detrital zircons from this paragneiss yields a Laurentian (Mesoproterozoic) signature, which suggests that the structurally concordant contact between volcanic rocks of the Chopawamsic Formation and paragneiss is either a pre-Alleghanian fault or an unconformity.
Suggested Citation
Carter, M.W., McAleer, R.J., Holm-Denoma, C.S., Spears, D.B., Regan, S.P., Burton, W.C., and Evans, N.H., 2020, Geochronologic age constraints on tectonostratigraphic units of the central Virginia Piedmont, USA: U.S. Geological Survey Professional Paper 1861, 28 p., https://doi.org/10.3133/pp1861.
ISSN: 2330-7102 (online)
Study Area
Table of Contents
- Acknowledgments
- Abstract
- Introduction
- Analytical Methods
- Results
- Discussion
- Conclusions
- References Cited
- Appendix 1. Laser Ablation-Inductively Coupled Plasma-Mass Spectrometry (LA-ICP-MS) Methodology
- Appendix 2. Secondary Ionization Mass Spectrometry Methodology
| Publication type | Report |
|---|---|
| Publication Subtype | USGS Numbered Series |
| Title | Geochronologic age constraints on tectonostratigraphic units of the central Virginia Piedmont, USA |
| Series title | Professional Paper |
| Series number | 1861 |
| DOI | 10.3133/pp1861 |
| Year Published | 2020 |
| Language | English |
| Publisher | U.S. Geological Survey |
| Publisher location | Reston, VA |
| Contributing office(s) | Eastern Geology and Paleoclimate Science Center |
| Description | Report: vi, 28 p.; 2 Tables |
| Country | United States |
| State | Virginia |
| Other Geospatial | central Virginia Piedmont |
| Online Only (Y/N) | Y |
| Additional Online Files (Y/N) | Y |
| Google Analytic Metrics | Metrics page |