Fractal study on fault system of Carboniferous in Junggar Basin based on GIS
Fault system is a significant evidence of tectonic movement during crust tectonic evolution and may play an more important role in oil-gas accumulation process than other tectonic types in sedimentary basin. Carboniferous surface faults in Junggar Basin developed well and varied in size and distribution. There are about 200 faults in Carboniferous, and 187 of them are thrust faults. Chaos-fractals theories have been widely investigated and great progress has been made in the past three decades. One of the important conception-fractal dimension had become a powerful tool for describing non-linearity dynamical system characteristic. The clustered objects in nature are often fractal and fault system distribution in space is inhomogeneous, always occurs in groups, so we can describe spatial distribution of faults from the point of fractal dimension. Fractal dimension of fault system is a comprehensive factor associated with fault number, size, combination modes and dynamics mechanism, so it can evaluate the complexity of fault system quantitatively. The relationship between fault system and oil-gas accumulation is a focus and difficulty problem in petroleum geology, and fractal dimension is a new tool for describing fault distribution and predicting potential areas of hydrocarbon resources. Geographic Information System (GIS) is a kind of technological system collecting, storing, managing, computing, analyzing, displaying and describing the geospatial information supported by computer software and hardware. In the last 15–20 years, GIS have been increasingly used to address a wide variety of geoscience problems. Weights-of-evidence models use the theory of conditional probability to quantify spatial association between fractal dimension and oil-gas accumulation. The weights of evidence are combined with the prior probability of occurrence of oil-gas accumulation using Bayes'rule in a loglinear form under an assumption of conditional independence of the dimension maps to derive posterior probability of occurrence of oil-gas accumulation. In this paper, we first vectorize the fault system in Carboniferous of Junggar Basin in GIS software and store it as polyline layer in Geodatabase of GIS to manage and analyze, then calculate the fractal dimension of three types which are box dimension, information dimension and cumulative length dimension using spatial functions of GIS, in the last use weights-of-evidence model to calculate the correlation coefficients in GIS environment between oil-gas accumulation and three types of fractal dimension in order to quantity the importance of fault system.
Fractal Estimation Using Extended Triangularisation and Box Counting Algorithm for any Geo-Referenced Point Data in GIS
Fractal dimension is often used as a measure of how fast length, area, or volume increases or decreases with increase or decrease in scale, or as a measure of complexity of a system. In this paper, input depends only on the Geo-referenced point data where the point event has occurred. An Extended Triangularisation Algorithm is developed to cover the area of point data as a polygon and its perimeter is calculated. Box Counting Algorithm is applied on those point data to calculate the Fractal values, which in turn work as an input to Prediction Plot Linear Model, to show that fractal value increases or decreases as perimeter of Polygon increases or decreases. To validate this model, Crime data was used and its results were analyzed. It provides information to police officials about the intensity of crime, area of patrolling and deputation of police in the sensitivity area. This model could be applied for any Geo-referenced point data such as cancer data, hypertension data and so on.
Dictionary of Alaska Place Names
Introduction: This work is an alphabetical list of the geographic names that are now applied and have been applied to to places and features of the Alaska Landscape.