Argument supporting explosive igneous activity for the origin of "cryptoexplosion" structures in the midcontinent, United States: comments and reply

Article Abstract:

J. Luczaj opposed the hypothesis of M.R. Rampino and T. Volk, published in 1996, which stated that the explosive igneous activity for the origin of eight cryptoexplosion structures in a linear array in the midcontinental US had various ages and questioned the validity of the meteorite impact-string theory. However, questions were raised over Luzcaj's interpretation of age constraints which was not even supported by geological knowledge. Also, objections were raised regarding the unsupported assertion that shock metamorphic features led to endogenic terrestrial processes.

Research, Analysis, Volcanological research, Volcanism, Volcanic ash, tuff, etc., Volcanic rocks, Rocks, Igneous, Igneous rocks

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Biostratigraphic and radiometric age data question the Milankovitch characteristics of the Latemar cycle (Southern Alps, Italy): comment and reply

Article Abstract:

Peter Brack et al.'s study is commendable for clarifying the uncertainties in ages of stage boundaries by using zircon dating of well-correlated biostratigraphic zones. Results of their study show the lower Ladinian Buchenstein Formation to be 2 to 4 m.y. old. However, assumptions made about the periodic nature of the Latemar cycles, the sampling of the volcaniclastic rocks and the dating of the zircons must all be reviewed if only to reconcile their results with both the proposed origin of the Latemar cycles and Hellmann and Lippolt's dates.

Evaluation, Measurement, Natural history, Geology, Stratigraphic, Stratigraphy, Radioactive dating, Radiometric dating, Italian Alps, Geological time, Geochronology, Triassic period

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