Table 1. Dominant characteristics of the main volcanic extrusive seismic facies units on rifted volcanic margins.
| Seismic facies unit | Reflector characteristics | Volcanic facies |
Emplacement environment | ||
|---|---|---|---|---|---|
| Shape | Boundaries | Internal | |||
Outer SDR |
Wedge |
Top: high-amplitude, smooth being onlapped. Pseudo-escarpments. Base: seldom defined. |
Divergent-arcuate or -planar. Disrupted, non-systematic truncations. |
Flood basalts mixed with pillow basalts, sediments and sills. |
Deep marine |
Outer high |
Mound |
Top: high-amplitude being onlapped. Often planated. No base. |
Chaotic. |
Hyaloclastic flows and volcaniclastics. |
Shallow marine |
Inner SDR |
Wedge |
Top: high-amplitude, smooth being onlapped. Pseudo-escarpments. Base: seldom defined. |
Divergent-arcuate. Disrupted, non-systematic truncations. |
Flood basalts. |
Subaerial |
Landward flows |
Sheet |
Top: high-amplitude, smooth being onlapped or concordant. Base: low-amplitude, disrupted. |
Parallel to subparallel. High-amplitude, very disrupted. |
Flood basalts. |
Subaerial |
Lava delta |
Bank |
Top: high-amplitude, or reflector truncation. Base: reflector truncation. |
Prograding clinoform. Disrupted. |
Massive and fragmented basalts. Volcaniclastics. |
Coastal |
Inner flows |
Sheet |
Top: high-amplitude, disrupted, being onlapped or concordant. Base: negative polarity but often obscured. |
Chaotic or disrupted, subparallel. |
Massive and fragmented basalts. Volcaniclastics. |
Subaqueous |
Note: Data from Planke et al. (in press).