The Appalachian Geology of John M. Dennison: Rocks, People, and a Few Good Restaurants along the Way
Dr. John M. Dennison spent his career studying the Appalachians; teaching and mentoring his students and professional colleagues; publishing papers; leading field trips; and presenting ideas at regional, national, and international conferences. This volume is a collection of papers contributed by former students and colleagues to honor his memory. Topics include stratigraphy and paleontology ranging in age from Ordovician to Mississippian in Kentucky, New York, Tennessee, Virginia, and West Virginia; Devonian airfall tephras throughout the eastern United States; a Devonian lonestone; a Middle Eocene bentonite in North Carolina and its relationship to a volcanic swarm in western Virginia; and a 3D model of a ductile duplex in northwestern Georgia. The stratigraphic and geologic diversity of the papers reflects Dennison's many interests and collaborative relationships.
Arc-to-craton: Devonian air-fall tephras in the eastern United States
*E-mails: [email protected]; [email protected]; [email protected].
*E-mails: [email protected]; [email protected]; [email protected].
*E-mails: [email protected]; [email protected]; [email protected].
-
Published:August 12, 2020
-
CiteCitation
C.A. Ver Straeten*, D.J. Over*, G.C. Baird*, 2020. "Arc-to-craton: Devonian air-fall tephras in the eastern United States", The Appalachian Geology of John M. Dennison: Rocks, People, and a Few Good Restaurants along the Way, Katharine Lee Avary, Kenneth O. Hasson, Richard J. Diecchio
Download citation file:
- Share
ABSTRACT
More than 100 air-fall volcanic tephra beds are currently documented from Devonian strata in the eastern United States. These beds act as key sources of various geological data. These include within-basin to basin-to-basin correlation, globally useful geochronologic age dates, and a relatively detailed, if incomplete, record of Acadian–Neoacadian silicic volcanism. The tephras occur irregularly through the vertical Devonian succession, in clusters of several beds, or scattered as a few to single beds. In this contribution, their vertical and lateral distribution and recent radiometric dates are reviewed. Current unresolved issues include correlation of the classic Eifelian-age (lower Middle Devonian) Tioga tephras and dates related to the age of the Onondaga-Marcellus contact in the Appalachian Basin. Here, we used two approaches to examine the paleovolcanic record of Acadian–Neoacadian silicic magmatism and volcanism. Reexamination of volcanic phenocryst distribution maps from the Tioga tephras indicates not one but four or more volcanic sources along the orogen, between southeastern Pennsylvania and northern North Carolina. Finally, radiometric and relative ages of the sedimentary basin tephras are compared and contrasted with current radiometric ages of igneous rocks from New England. Despite data gaps and biases in both records, their comparisons provide insights into Devonian silicic igneous activity in the eastern United States, and into various issues of recognition, deposition, and preservation of tephras in the sedimentary rock record.
- Appalachian Basin
- ash falls
- basins
- correlation
- depositional environment
- Devonian
- Eastern U.S.
- Eifelian
- Famennian
- Frasnian
- Givetian
- igneous rocks
- lithofacies
- magmatism
- Marcellus Shale
- Middle Devonian
- New England
- North America
- Onondaga Limestone
- Paleozoic
- pyroclastics
- sedimentary basins
- stratigraphic units
- Tioga Bentonite
- United States
- Upper Devonian
- volcanic rocks
- volcanism