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Abstract
9-6 Schumacher, D., Witter, D. P., Meader, S. J., and Keith, S. B., 1976, Late Devonian tectonism in southeastern Arizona, in Wilt, J. C., and Jenney, J. P., editors, Tectonic Digest: Arizona Geological Society Digest, v. 10, p. 59-70.
Abstract
9-6 Schumacher, D., Witter, D. P., Meader, S. J., and Keith, S. B., 1976, Late Devonian tectonism in southeastern Arizona, in Wilt, J. C., and Jenney, J. P., editors, Tectonic Digest: Arizona Geological Society Digest, v. 10, p. 59-70.
ABS
Devonian strata in southeastern Arizona are assigned to the lower Upper Devonian (Frasnian) Martin Formation and the upper Upper Devonian (Famennian) Percha Formation. The name Percha Formation is here proposed for the sequence of slope-forming shales with overlying ledgy carbonates that occur above the Martin Formation throughout much of southern Arizona. Results of recent stratigraphic investigations of the Devonian show that some adjacent areas received greatly contrasting kinds and amounts of sediments and suggest that parts of the region may have been tectonically unstable during the Devonian. In order to more precisely determine the nature and location of Late Devonian structural changes, separate isopach maps were prepared for the Frasnian and Famennian. The Frasnian map reveals the presence of a relatively narrow positive element, the southwestern extension of the Defiance Positive area, extending from the Clifton-Morenci area to near Winkelman. Comparison of Frasnian and Famennian ispoach maps reveals that the Percha Formation attains its maximum thicknesses in a basin, or basins, which developed over the site of the preexisting positive area and whose limits coincide almost precisely with those of the positive area. The post-Martin, pre-Percha subsidence of the Frasnian positive element and the accompanying broad regional uplift of the Frasnian basins occurred in the early-middle Famennian and coincides with the beginnings of the Antler Orogeny in Nevada.
Key words
Arizona. Cochise County Arizona. Devonian. Famennian. Graham County Arizona. Greenlee County Arizona. isopach maps. maps. Martin Formation. paleogeography. Paleozoic. Percha Formation. Pima County Arizona. Pinal County Arizona. Southeast. stratigraphy. structural geology. tectonics. thickness. United States. Upper Devonian.
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Abstract
9-6 Schumacher, D., Witter, D. P., Meader, S. J., and Keith, S. B., 1976, Late Devonian tectonism in southeastern Arizona, in Wilt, J. C., and Jenney, J. P., editors, Tectonic Digest: Arizona Geological Society Digest, v. 10, p. 59-70.
ABS
Devonian strata in southeastern Arizona are assigned to the lower Upper Devonian (Frasnian) Martin Formation and the upper Upper Devonian (Famennian) Percha Formation. The name Percha Formation is here proposed for the sequence of slope-forming shales with overlying ledgy carbonates that occur above the Martin Formation throughout much of southern Arizona. Results of recent stratigraphic investigations of the Devonian show that some adjacent areas received greatly contrasting kinds and amounts of sediments and suggest that parts of the region may have been tectonically unstable during the Devonian. In order to more precisely determine the nature and location of Late Devonian structural changes, separate isopach maps were prepared for the Frasnian and Famennian. The Frasnian map reveals the presence of a relatively narrow positive element, the southwestern extension of the Defiance Positive area, extending from the Clifton-Morenci area to near Winkelman. Comparison of Frasnian and Famennian ispoach maps reveals that the Percha Formation attains its maximum thicknesses in a basin, or basins, which developed over the site of the preexisting positive area and whose limits coincide almost precisely with those of the positive area. The post-Martin, pre-Percha subsidence of the Frasnian positive element and the accompanying broad regional uplift of the Frasnian basins occurred in the early-middle Famennian and coincides with the beginnings of the Antler Orogeny in Nevada.
Key words
Arizona. Cochise County Arizona. Devonian. Famennian. Graham County Arizona. Greenlee County Arizona. isopach maps. maps. Martin Formation. paleogeography. Paleozoic. Percha Formation. Pima County Arizona. Pinal County Arizona. Southeast. stratigraphy. structural geology. tectonics. thickness. United States. Upper Devonian.
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