ISSN:
1365-3121
Source:
Blackwell Publishing Journal Backfiles 1879-2005
Topics:
Geosciences
Notes:
Kolmogorov's model of the distribution of bed thicknesses is assessed by numerical simulations of a sedimentation process, assumed to be a random time-series of alternating depositional and erosional episodes conformable with a stationary Markov process in a state of equilibrium. The study supports the validity of the main point of the model. The random time-series process generates a succession of beds with ‘positive’ (preserved) and ‘negative’ (eroded) thicknesses, the frequency distribution of which, f(x), spans the range of positive to negative x-values. The beds with negative thicknesses are absent in the stratigraphic record, whereby the measured bed thicknesses show a frequency distribution, f*(x | x 〉 0), that is left-side truncated, cut off at the zero thickness value. The numerical simulations further indicate that f(x) is a ‘composite’ geometrical distribution, whose actual form changes progressively with pd, the probability of sediment deposition relative to erosion. The distribution f(x) invariably has a maximum at x≤0, such that the truncated distribution f*(x) for pd≥0.5 is a simple geometrical distribution regardless of pd value. The f*(x) distribution will appear to be a negative exponential distribution when based on the bed-thickness data measured in a conventional metric scale. Data sets from four different turbidite successions in the Cenozoic of Japan, each comprising a few thousand beds, show this type of distribution. However, the sandstone-capping shales in one of the turbidite successions show a truncated Gaussian distribution, attributed to a significant component of non-turbiditic mud. No universal form of bed-thickness distribution can be assumed for the Kolmogorov model. The form of bed-thickness distribution may vary with the type of the depositional process and the character of the sedimentary environment.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1111/j.1365-3121.1995.tb00537.x
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