Stromatoporoids and the Upper Devonian Alamo Impact Breccia of southeastern Nevada
Eleven species in 10 genera of stromatoporoids were identified from within and below the Alamo Breccia of southeastern Nevada, in an effort to determine the excavation depth of a bolide impact that occurred during the Late Devonian, approximately 382 Ma. The specimens identified in this study are taxa that are also known from Iowa, Canada, and other parts of the world. Actinostroma cf. A. clathratum, Clathrocoilona cf. C. involuta, Stictostroma maclareni, Trupetostroma bassleri, and Arctostroma contextum were identified from stromatoporoid-bearing beds located in the Guilmette Formation below the Alamo Breccia. Atelodictyon sp. 1, Hammatstroma albertense, and Hermatoporella sp. 1 were identified from both below and within the Alamo Breccia. The remaining species: Actinostroma sp. 1, Atopostroma distans, and Habrostroma turbinatum were identified from within the Alamo Breccia. Based on the results of this study, a definite depth of penetration cannot be obtained. However, using stromatoporoid biostratigraphy, it is most likely that the bolide impacted no deeper than rocks of Emsian age.