--> ABSTRACT: Ordovician Chitinozoan Zones of Great Basin, by T. J. Hutter; #91040 (2010)

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Ordovician Chitinozoan Zones of Great Basin

T. J. Hutter

Within the Basin and Range province of the Great Basin of the western United States, Ordovician chitinozoans have been recovered in two major lithic facies; the "western" eugeosynclinal facies and the "eastern" miogeosynclinal facies. Chitinozoans recovered from these facies range in age from Arenig to Ashgill. Extensive collections from this area make possible the establishment of chitinozoan faunal interval zones from the Ordovician of this area. Selected species of biostratigraphic value include, in chronostratigraphic order, Lagenochitina ovoidea Benoit and Taugourdeau, 1961, Conochitina langei Combaz and Peniguel, 1972, Conochitina poumoti Combaz and Penique, Desmochitina cf. nodosa Eisenack, 1931, Conochitina maclartii Combaz and Peniguel, 1972, Conochitina robusta isenack, 1959, Angochitina capillata Eisenack, 1937, Sphaerochitina lepta Jenkins, 1970, and Ancyrochitina merga Jenkins, 1970. In many cases, these zones can be divided into additional sub-zones using chitinozoans and acritarchs. In all cases, these chitinozoan faunal zones are contrasted with established "American" graptolite zones of the area, as well as correlated with British standard graptolite zones. The composition of these faunas of the western United States Great Basin is similar to that of the Marathon region of west Texas and the Basin Ranges of Arizona and New Mexico, to which direct comparisons have been made. There also appears to be a great similarity with the microfaunas and microfloras of the Ordovician of the Canning basin of western Australia. The Ordovician chitinozo n faunal interval zones established for the Basin and Range province of the Great Basin of the western United States also appear to be applicable to the Marathon region of west Texas and the Basin Ranges of Arizona and New Mexico.

AAPG Search and Discovery Article #91040©1987 AAPG Rocky Mountain Section Meeting, Boise, Idaho, September 13-16, 1987.