Stable isotropic evidence for relative and eustatic sea-level changes in Eocence to Oligocene carbonates, Baldwin County, Alabama: discussion
Article Abstract:
The accuracy of the biostratigraphic determination of the boundary and the age of interval at the Bay Minette borehole presented by Baum et al. in 1994 is discussed. Their paper presents the boundary as separating upper middle Eocene Lisbon Formation from uppermost middle to lower upper Eocene Gosport and Moodys Branch Formations. However, the technique used cannot assure accuracy because it is not applicable to shallow-water marine sequences. A more accurate indicator, the fossil groups of rapid evolution, shows that the sequence is middle Eocene, Lisbon Formation, not Gosport and lower Moodys Branch Formations.
Publication Name: The Geological Society of America Bulletin
Subject: Earth sciences
ISSN: 0016-7606
Year: 1996
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Discussion
Article Abstract:
McKee and Conrad's suggestion that there was a magmatic episode in the Northern part of the White Mountains, CA, during Late Cretaceous Period as indicated by biotite Ar-Ar dates for granitic rocks found in the region is analyzed. McKee and Conrad estimated the McAfee Creek pluton, one of the Cretaceous intrusions, to be 83.6 Ma based on a biotite age. However, this intrusion has a U-Pb zircon age of 100 plus or minus 1 Ma which means that nearly all of the intrusions in the White Mountains were emplaced approximately 15 m.y. before the Cretaceous time.
Publication Name: The Geological Society of America Bulletin
Subject: Earth sciences
ISSN: 0016-7606
Year: 1997
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Geological reasoning: geology as an interpretive and historical science: discussion
Article Abstract:
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Publication Name: The Geological Society of America Bulletin
Subject: Earth sciences
ISSN: 0016-7606
Year: 1996
User Contributions:
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