Characteristics
Despite the differences in origin and formation, most VPMs share the same characteristics:
- 4 to 7 km thick basaltic and (frequently) silicic subaerial flows; dike swarms and sills running parallel to continent-facing normal faults.
- 10 to 15 km thick bodies in the lower crust (HVLC) show high seismic P-Wave velocities, between 7.1 and 7.8 km/s which lie under the transitional crust (crust between continental crust and oceanic crust).
- Seaward Dipping Reflector (SDR) series: Inner SDR’s overlay transitional continental crust. They are composed of varying mixtures of subaerial volcanic flows, volcaniclastic and non-volcanic sediments which range from 50–150 km wide and are 5–10 km thick. Outer SDR’s overlay transitional oceanic crust are composed of submarine basaltic flows which range from 3 to 9 km thick.
Read more about this topic: Volcanic Passive Margin