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The AAPG/Datapages Combined Publications Database

AAPG Bulletin


Volume: 56 (1972)

Issue: 3. (March)

First Page: 642

Last Page: 642

Title: Mississippian Conodont Zones of Southeastern Arizona: ABSTRACT

Author(s): R. D. Norby, R. F. Lundin

Article Type: Meeting abstract


Analyses of conodont faunas from Mississippian rocks in southeastern Arizona differentiate 7 conodont zones and 1 zone essentially barren of conodonts. Based on this conodont zonation, the Escabrosa Limestone ranges in age from late Kinderhookian (Siphonodella isosticha-S. cooperi zone) to late Meramecian (Taphrognathus varians-Apatognathus-Cavusgnathus zone). The Paradise Formation, represented by only the Gnathodus girtyi-Cavusgnathus zone, is middle Chesterian in age. Accordingly, the boundaries of both formations are represented by unconformities. The conodont fauna is large and diversified: 387 samples from 7 localities yielded 6,600 specimens representing 118 form species of 30 form genera. Species of Siphonodella, Pseudopolygnathus, Polygnathus, Gnathodus, Cavusgna hus, Apatognathus, and Taphrognathus are especially important in the zonation. The zonation recognized suggests relatively rapid transgression of Mississippian seas across a shelf of low relief in southeastern Arizona.

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Copyright 1997 American Association of Petroleum Geologists