Sedimentation Accumulation Rate Formula
Calculates the rate of geological sediment accumulation in mm/kyr or m/Ma, corrected for burial compaction and porosity reduction phi.
\[ R_{sed} = \frac{\Delta z_{compacted}}{\Delta t \cdot (1 - \phi_0)} \cdot (1 - \phi_z) \]
Plain Text Formula:
R_sed = (Delta_z / Delta_t) * ((1 - phi_z) / (1 - phi_0))
📐 Variable Definitions & Parameters
| Symbol | Variable Name | Standard Unit | Physical Definition |
|---|---|---|---|
| \[ R_{sed} \] | Decompacted Sedimentation Rate | m/Ma or mm/kyr | Original rate of deposition on the sea floor |
| \[ \Delta z \] | Stratigraphic Thickness | meters (m) | Measured rock layer thickness between two dated ash beds |
| \[ \Delta t \] | Chronostratigraphic Duration | Ma | Absolute time difference between upper and lower boundary markers |
| \[ \phi_0, \phi_z \] | Initial and Current Porosity | fraction | Void ratio reduction under lithostatic overburden |
💡 Worked Engineering Example
Problem Statement:
A 120-meter limestone section accumulated between 66.0 Ma and 60.0 Ma (Delta t = 6.0 Ma). Find mean sedimentation rate.
Step-by-Step Solution:
- Rate = 120 m / 6.0 Ma = 20 m/Ma = 20 mm/kyr
🎯 Result: The average sedimentation rate was 20 meters per million years.