Research Article
Multiscale Erosion Surfaces of the Organic-Rich Barnett Shale, Fort Worth Basin, USA
Table 3
Characteristic features of multi-scale erosional surfaces.
| Characters | Sequence-scale erosion surface | Parasequence-scale erosion surface | Event-scale erosion surface |
| Relief | More than 25 mm | Range between 8 and 20 mm | <5 mm | Surface nature | Irregular, scoured, cutting down | Sharp, irregular to gradational | Sharp | Lithofacies | siliceous non calcareous mudstone and Siliceous calcareous mudstone | Siliceous non calcareous mudstone and Siliceous calcareous mudstone | Clay-rich mudstone facies | Reworked concretions | Rounded to subrounded shale intraclasts | Subrounded phosphatic pellets | Calcareous concretions | Shelly laminae | Highly compacted and horizontally oriented shell fragments | Traces of thin disconnected shelly laminae | Rarely occurred | Shale rip-up clasts | Rarely occurred | Common | Rarely occurred | Spectral gamma ray pattern | Abrupt change (decreasing and increasing) | Marking the end of upward increasing or decreasing spectral Gamma Ray pattern | Does not Apply | Energy levels | High energy enough to reworked shale intraclasts and other components | Low energy where the shale rip-up clasts suspended in the sea bed layer | Low bottom energy levels |
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