Elevating Geoscience in the Southeastern United States: New Ideas about Old Terranes—Field Guides for the GSA Southeastern Section Meeting, Blacksburg, Virginia, 2014
This volume includes 10 field guides that explore the diverse geology of the southern and central Appalachians. These guides examine both ancient rocks and modern landscape processes, highlighting new research ideas regarding these old terranes. Three guides focus on the geology of the Appalachian Plateau and Valley and Ridge, considering topics such as the enigmatic Eocene igneous rocks, the gas-rich Marcellus and Millboro Shales, and new models for karst formation. The 2011 M5.8 Mineral, Virginia, earthquake literally shook up our understanding of the Piedmont and two guides focus on new research in the epicentral region. Two guides take in the Paleozoic to Proterozoic geology of the Blue Ridge province. The volume is rounded out by three guides focused on Mesozoic geology, including the world-class Lagerst–tte fauna in the Dan River basin, a unique uranium deposit at Coles Hill, Virginia, and the tectonics of the Scottsville Basin.
Geology and neotectonism in the epicentral area of the 2011 M5.8 Mineral, Virginia, earthquake
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Published:January 01, 2014
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CiteCitation
William C. Burton, David B. Spears, Richard W. Harrison, Nick H. Evans, J. Stephen Schindler, Ronald Counts, 2014. "Geology and neotectonism in the epicentral area of the 2011 M5.8 Mineral, Virginia, earthquake", Elevating Geoscience in the Southeastern United States: New Ideas about Old Terranes—Field Guides for the GSA Southeastern Section Meeting, Blacksburg, Virginia, 2014, Christopher M. Bailey, Lorrie V. Coiner
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Abstract
This field guide covers a two-day west-to-east transect across the epicentral region of the 2011 M5.8 Mineral, Virginia, earthquake, the largest ever recorded in the Central Virginia seismic zone. The field trip highlights results of recent bedrock and surficial geologic mapping in two adjoining 7.5-min quadrangles, the Ferncliff and the Pendleton, which together encompass the epicenter and most of the 2011–2012 aftershocks. Tectonic history of the region includes early Paleozoic accretion of an island arc (Ordovician Chopawamsic Formation) to Laurentia, intrusion of a granodiorite pluton (Ordovician Ellisville pluton), and formation of a post-Chopawamsic successor basin (Ordovician Quantico Formation), all accompanied by early Paleozoic regional deformation and metamorphism. Local transpressional faulting and retrograde metamorphism occurred in the late Paleozoic, followed by diabase dike intrusion and possible local normal faulting in the early Mesozoic. The overall goal of the bedrock mapping is to determine what existing geologic structures might have been reactivated during the 2011 seismic event, and surficial deposits along the South Anna River are being mapped in order to determine possible neotectonic uplift. In addition to bedrock and surficial studies, we have excavated trenches in an area that contains two late Paleozoic faults and represents the updip projection of the causative fault for the 2011 quake. The trenches reveal faulting that has offset surficial deposits dated as Quaternary in age, as well as numerous other brittle structures that suggest a geologically recent history of neotectonic activity.
- accretion
- aftershocks
- amphibolites
- Appalachians
- Atlantic Coastal Plain
- bedrock
- Blue Ridge Province
- brittle deformation
- Chopawamsic Formation
- deformation
- earthquakes
- epicenters
- extension tectonics
- faults
- field trips
- foliation
- guidebook
- island arcs
- Laurentia
- lower Paleozoic
- magnitude
- mapping
- matrix
- Mesozoic
- metamorphic rocks
- metamorphism
- neotectonics
- normal faults
- North America
- Paleozoic
- Piedmont
- reactivation
- retrograde metamorphism
- reverse faults
- road log
- seismotectonics
- tectonics
- textures
- transpression
- trenching
- United States
- uplifts
- central Virginia
- Quantico Formation
- Pendleton Quadrangle
- Ellisville Pluton
- Mine Run Complex
- Mineral earthquake 2011
- Ferncliff Quadrangle
- South Anna River
- Quail Fault