论地质概念与空间分析方法的关系:以矿集区判定为例

Relationship between geologic concepts and spatial analysis methods:a case of metallogenic district mapping

地质矿产信息化成果集中体现在两个方面:包含地质矿产空间数据库的高速发展和空间分析方法的极大丰富。上述两个方面的高效应用均以前人研究成果(地质概念、理论、规律)为基础和依据,地质概念、理论、规律同空间分析方法的结合是地质矿产数据库高效应用的技术关键,实现这一结合的纽带是地质概念、理论和规律所包含的空间分析思想。以矿集区概念为理论基础,以巴尔喀什地区为示范,探讨了矿集区判定所包含的空间分析思想,论述了依据该空间分析思想所采用的空间分析方法,获得了矿集区判定结果,实现了理论内涵和技术方法的结合。

The achievement of information of geology and metallogenic is reflected on two aspects: One is the high development of geodatabases which include the geology concepts system,the other is great abundant of the spatial analysis methods which are based on geodatabases.The effective application of the two aspects is theoretically guided by geologic concepts and theories.The technological key point of effective application is the combination of geologic concepts,theories and corresponding spatial analysis methods.How to realize the combination depends on the original spatial analytic thoughts which are embodied in geology concepts and theories.That is the original spatial analytic thoughts are proved to be the link between geology concepts,theories and spatial analysis methods on GIS platform.Only in the light of these thoughts can we integrate theories and methods in geodatabase.This paper aims at discussing the spatial analytic thoughts which embodied in geologic concepts and theories as well as combining these concepts and theories with specific spatial analysis methods in the application of metallogenic district mapping in the case of Balkhash.Metallogenic district means concentration of different size deposits and occurrences.The concept embodies the thought of density analysis and integration different size deposits and occurrences.The corresponding spatial analysis method is density analysis and raster calculation.They are included in spatial analysis tools of ArcGIS.Density analysis discusses the trend of concentration of points and lines,such as deposits and faults.In this paper,different size deposits have different spatial concentrating trend,and their weights are also different during integration.There are some factors should be considered when density analysis is performed.The most important factor is Search Radius.By density analysis,the spatial distributing density maps of specific size deposit can be obtained.The maps of large and medium sizes deposits reflect the trend of microscopic regional concentration,and the maps of small ones show the trend of local concentration.Raster calculation is used to integrate different density maps of specific size deposits.It is performed by raster calculator tool in ArcGIS.Before integration,the dimension of specific size density maps should be unified through extreme-value transformation or standard transformation.In the paper,the extreme-value transformation is used,and the transformed density maps with 0-1 value ranges are obtained without changing spatial distributing pattern.At last,by raster calculator,all single transformed density maps are integrated and the Metallogenic districts are mapped.