Middle and upper Paleozoic granitic rocks in the Piedmont near Fredericksburg, Virginia; geochronology
No abstract available.
Virginia↗
Geology topics
M. F. Newell
Publications and source records attributed to M. F. Newell.
Isotopic U-Pb ages of zircon from the granitoids of the central Sierra Nevada, California
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Professional Paper↗
Zircon ages of felsic volcanic rocks in the upper Precambrian of the Blue Ridge, Appalachian mountains
Five zircon samples from Pennsylvania, Virginia, and North Carolina yield discordant uranium-lead ages which suggest an original age of 820 million years and an episodic lead loss at 240 million years. The indicated age of lead loss is interpreted as the age of movement of the Blue Ridge thrust sheet.
North Carolina, Pennsylvania, Virginia↗
Effects of weathering on the UPb ages of zircon from the Morton Gneiss, Minnesota
Weathering has caused large losses of lead from the zircon in the residual clay derived from the Morton Gneiss of southwestern Minnesota, drastically reducing the 206Pb/238U and the 207Pb/235U ages. The 207Pb/206Pb age probably has not been significantly affected. Loss of lead by leaching during weathering has not been adequately considered in explanation of discordant ages of zircon.
Minnesota↗