A new Cretaceous-Tertiary boundary locality in the western Powder River basin, Wyoming: Biological and geological implications
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Abstract
A newly discovered Cretaceous-Tertiary (K-T) boundary locality in the western Powder River basin, Wyoming, is characterized by a palynologically defined extinction horizon, a fern-spore abundance anomaly, a strong iridium anomaly, and shock-metamorphosed quartz grains. Detailed microstratigraphic analyses show that about one third of the palynoflora (mostly angiosperm pollen) disappeared abruptly, placing the K-T boundary within a distinctive, 1- to 2-cm-thick claystone layer. Shocked quartz grains are concentrated at the top of this layer, and although fern-spore and iridium concentrations are high in this layer, they reach their maximum concentrations in a 2-cm-thick carbonaceous claystone that overlies the boundary claystone layer. The evidence supports the theory that the K-T boundary event was associated with the impact of an extraterrestrial body or bodies. Palynological analyses of samples from the K-T boundary interval document extensive changes in the flora that resulted from the boundary event. The palynologically and geochemically defined K-T boundary provides a unique time-line of use in regional basin analysis.
Study Area
| Publication type | Article |
|---|---|
| Publication Subtype | Journal Article |
| Title | A new Cretaceous-Tertiary boundary locality in the western Powder River basin, Wyoming: Biological and geological implications |
| Series title | Cretaceous Research |
| DOI | 10.1016/0195-6671(92)90026-M |
| Volume | 13 |
| Issue | 1 |
| Year Published | 1992 |
| Language | English |
| Publisher | Elsevier |
| Description | 28 p. |
| First page | 3 |
| Last page | 30 |
| Country | United States |
| State | Wyoming |
| Other Geospatial | western Powder River basin |
| Google Analytic Metrics | Metrics page |