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Back-stripping (also back stripping or backstripping) is a geophysical analysis technique used on sedimentary rock sequences - the technique is used to quantitatively estimate the depth that the basement would be in the absence of sediment and water loading. This depth provides a measure of the unknown tectonic driving forces that are responsible for basin formation (otherwise known as tectonic subsidence or uplift). By comparing backstripped curves to theoretical curves for basin subsidence and uplift it is possible to deduce information on the basin forming mechanisms.〔(University of Wyoming: Backstripping )〕 The technique developed by Watts & Ryan in 1976 〔(Flexure of the lithosphere and continental margin basins ), A.B. Watts, W.B.F. Ryan (1976), Techtonophysics]〕 allows for the recovery of the basement subsidence and uplift history in the absence of sediment and water loading and, therefore isolate the contribution from the tectonic forces responsible for the formation of a rift basin.〔(Chapter 4: Well Backstripping and Subsidence Analysis ) in Gravity Anomalies, Flexure and the Thermo-Mechanical Evolution of the West Iberia Margin and its Conjugate of Newfoundland (2008), PhD Thesis by Tiago Cunha〕 It is a method by which successive layers of basin fill sediment are "stripped off" the total stratigraphy during analysis of that basin's history. In a typical scenario, a sedimentary basin deepens away from a marginal flexure, and the accompanying isochronous strata typically thicken basinward. By isolating the isochronous packages one-by-one, these can be "peeled off" or backstripped - and the lower bounding surface rotated upward to a datum. By successively backstripping isochrons, the basin's deepening history can be plotted in reverse, leading to clues as to its tectonic or isostatic origin. A more complete analysis uses decompaction of the remaining sequence following each stage of the back-stripping. This takes into account the amount of compaction caused by the loading of the later layers and allows a better estimation of the depositional thickness of the remaining layers and the variation of water depth with time. ==General Theory== As a result of their porosity, sedimentary strata are compacted by overlaying sedimentary layers after deposition. Consequently, the thickness of each layer in a sedimentary sequence was larger at the time of its deposition than it is when measured in the field. In order to consider the influence of sediment compaction on the thickness and density of the stratigraphic column, the porosity must be known.〔(Geodynamics of the Lithosphere (2nd edn.) ), K. Stüwe (2007), New York: Springer]〕 Empirical studies show that the porosity of rocks decreases exponentially with depth. In general we can describe this with the relationship: : where is the porosity of the rock at depth , is the porosity at the surface and is a rock specific compaction constant. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Back-stripping」の詳細全文を読む スポンサード リンク
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