Florence Bascom Geoscience Center


Filter Total Items: 388
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Year Published: 1992

Alleghanian development of the Goat Rock fault zone, southernmost Appalachians: Temporal compatibility with the master decollement

The Goat Rock and associated Bartletts Ferry fault zones, which mark the eastern margin of the Pine Mountain Grenville basement massif, are controversial due to the suggestion that they are rare exposed segments of the late Paleozoic southern Appalachian master decollement. The controversy in part stems from reported middle Paleozoic (Acadian)...

Steltenpohl, Mark G.; Goldberg, S.; Hanley, T.B.; Kunk, Michael J.

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Year Published: 1992

Calibration of the latest Eocene-Oligocene geomagnetic polarity time scale using 40 Ar/ 39 Ar dated ignimbrites

A discontinuous record of late Eocene-Oligocene geomagnetic polarity has been determined using high-precision (±<0.15 m.y.) 40Ar/39Ar sanidine dating and a paleomagnetic study of 37-27 Ma ignimbrites in New Mexico, Colorado, and Texas. This record provides age control for several geomagnetic polarity reversals that occurred during three...

McIntosh, W.C.; Geissman, J.W.; Chapin, C.E.; Kunk, Michael J.

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Year Published: 1990

Geology, geophysics, and geochronology of the Manson impact structure

A problem with the impact hypothesis for the Cretaceous/Tertiary (K/T) mass extinction is the apparent absence of an identifiable impact site. The Manson impact structure is a candidate site because of its size (the largest such structure recognized in the United States); in addition, the largest and most abundant shocked quartz grains at the K/T...

Hartung, J.B.; Kunk, Michael J.; Anderson, R.R.

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Year Published: 1985

Age of biostratigraphic horizons within the Ordovician and Silurian systems

Three samples that have a bearing on the age of horizons within the Ordovician and Silurian systems, two previously dated by the conventional K-Ar method and one by the 40Ar/39 Ar total-fusion method, have been reanalysed using the 40Ar/39Ar age-spectrum method. Conventional K-Ar and total-fusion 40Ar/39Ar ages can always be...

Kunk, Michael J.; Sutter, J.; Obradovich, J.D.; Lanphere, Marvin A.