Question

When performing backstripping, which process must be subtracted from the total sediment thickness to isolate the tectonic component of basin subsidence?

Accepted Answer

To isolate the tectonic component of basin subsidence through backstripping, you must subtract the effects of sediment loading. Sediment loading refers to the downward bending or compaction of the Earth&#x27;s crust caused by the weight of accumulated rock and mineral layers. As sediments fill a basin, their mass creates a force that pushes the basement rock deeper into the underlying mantle. This process, known as isostatic adjustment, causes significant subsidence that is independent of the tectonic forces originally responsible for creating the basin. To determine the tectonic subsidence—the movement driven solely by heat flow, lithospheric thinning, or mantle dynamics—you first calculate the total observed subsidence, which is the depth of the basement rock below the original sea level. You then mathematically remove the sediment column by accounting for two factors: the compaction of the sediments due to the pressure of overlying layers and the isostatic compensation provided by the mantle as the weight of the sediments is removed. Once the gravitational effect of the sediment pile is subtracted from the total basin depth, the remaining value represents the subsidence caused exclusively by tectonic processes.

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When performing backstripping, which process must be subtracted from the total sediment thickness to isolate the tectonic component of basin subsidence?