Integration analysis technique of multi data: An effective way of recognizing Uranium Mtallogenic region

Integration analysis technique of multi data: An effective way of recognizing Uranium Metallogenic region

He Zhongi, Guo Xuetao , Hou jianxin, Wang Saiwei
Beijing research Institute of Uranium Geology
Beijing ,China

Abstract
Recognizing uranium metallogenic region is one important topic in the research of uranium metallogenic province the integration analysis technique of multi data based on the data collected mostly from remote sensing geology air borne magnetic and radioactive surveys and on image processing system is an effective way of recognizing uranium metallogenic region this paper tries to delineate the basic contents and application result of IATMD through recognizing a Mesco Cenozonic related uranium metallogenic region on north china Platform.

Introduction
Uranium metallogenic region is the most promising region for ore grade mineralization with in uranium metallogenic province .It has favorable geologic conditions for uranium metallogenic regions with in which one or more uranium deposits may be found.

Taking the recognition of Mesozoic to Cenozoic magmatisim related uranium metallogenic region on North region china platform as an example this paper tries to illustrate the application procedures and the results of IMTAD based mainly on remote sensing data and digital image processing system is composed of the analysis of geologic model for uranium metallogenic region 2 the selection of characteristic information of the best combination of multi data 5 the establishment of multi data image model and 6 the recognizant of uranium metallogenic region.

Geologic features
The most prominent geologic feature of uranium metallogenic provinces of eastern china lies in their younger ages of Mesozoic to Cenozoic period their formation is believed to be related to the strong interaction between pacific plate and Asian continental margin the uranium mineralization on north china platform is closely related to the Meso Cenozoic remobilization of structures and magmatism.

The study area is located on the northern margin of North China platform major types of rocks and average uranium content in the study are listed in table 1 a volcanic type uranium deposited was discovered in the area .uranium mineralization resulted from the gradual accumulation of uranium during the long term geological process in late Jurassic time the basement reeling resulted in the acid volcanism and the preliminary uranium enrichment in rhylites later on the magnetic hydrothermal solution from the cretaceous tertiary intermediate basic volcanism released uranium in the basement rocks and the over lying during its ascent on the other hand the surface water leached uranium in the r during its descent when the ascending magmata solution and descending metrics water met and mixed the physical chemicals conditions considerably changed there fore uranium precipitated from the mixed solution and uranium mineralization occurred (Fig. 1).

Table 1. Major types rocks and their average uranium content in the study area.

Period	Lithology	Average U content(ppm)
Quaternary	Sediments, Debris
Tertiary	Basalts
Cretaceous	Andesites	1.8
Late Jurassic	Upper rhyolitic lava	5.4
	Middle trachytic lava	3.6
	Lower rhyolitic tuff and andesitic rocks	1.6
Precambrain	Biotite granulite , Hornblende plagiogneiss, Potassium migmatite	1.7-4.0

Fig. 1 Geological Model of Uranium Mineralization in the study area

According to the above geological model analysis of uranium mineralization the recognition criteria for uranium metallogenic region on North China platform are concluded as follows.

The medium sized basins of U-rich acidic volcanism upon the palaeo crystalline basement.
Those basin controlling fault zones along which sub volcanic intrusions and hydrothermal alteration present.
The circular and radiant fractures in major volcanic apparatuses with in volcanic basins.
The acidic volcanic basins superimposed by intermediate basic volcanism and tension faulting of cretaceous to tertiary age.
The U rich rhyolitic rocks which were hydrothermal altered
The proper erosion of volcanic basins where top parts of sub volcanic intrusion are out cropped.

Basic data
The basic way for recognition of uranium metallogenic region is through determining the recognition criteria and their spatial distribution.

According to the physical properties of the uranium mineralization related geologic elements existing data and experience we selected four types of data. 3 aeromagnetic data 4 aero radiometric data as the basic data in the practical study.

Quaternary sediments and debrics are wide spread in the study area it is hard to study regional fault patterns in short time with the traditional geologic methods therefore the lineament and circular features on TM images are interpreted in detail then they are input in to computer by digitizing .The direction frequency statistics of lineaments is carried out .This is necessary for the determination of major fault zones in one direction based on the density analysis to the lineaments in that direction similarly the diameter frequency statistic is employed since circular feature with different size often have different geologic meaning .it is important that circular features in volcanic rock area are often the indicates of faults.

In order to fully utilize the image processing system in multi data integration analysis the geologic map is input in to computer by digitizing the process is the quantizing of different rock units.

Aeromagnetic data are upward continued and directionally filtered
Furthermore, the linear magnetic anomalies which reflect the faults in different depth and different directions are extracted the extracted linear magnetic anomalies are superimposed by lineament density and circle image in image preprocessing system so as determine the fault zones different depth and trending .

The aeroradiometric data are also input in to computer in image processing system the geologic maps TM images interpreted lineaments and circles are super imposed by the extracted radioactive anomalies to determine the spatial distributions of the radioactive anomalies and the relationship with geologic bodies.

Analysis of Multi-Data
The task of IATMD is to make scientific combination analysis to the selected data in image processing system so that spatial distribution of major geologic mineralization elements and their relationship elements of discovered deposit we can establish the multi parameters identification image model for the uranium metallogenic region.

In the study area the fault zones which control the late Jurassic and cretaceous volcanic basins are prominently valuable because to a considerable degree these fault zones control the distribution of the major uranium source rocks acidic lava and intrusions of the heat source intermediate to basic volcanism also these fault zones control the distribution of volcanic sedimentary basins where metallogenic fluids and water tend to concentrate that is to say these fault zones control the spatial distribution of three major mineralization perquisites uranium heat and water sources the present data suggest that basin controlling faults are steeply dipping basement or basement transecting faults which reach ground surface.

In order to determine the basin controlling faults and their spatial distribution we must first study major fault systems then the basin controlling faults can be found upon their geologic properties the procedures are 1 making combination analysis to the interpreted then digitized lineaments and digitized geologic map determine general distribution of the surface fault system 2 operating the integration analysis to lineament density of specific direction and the linear magnetic anomalies which are extracted from the up ward continued and directional filtered total magnetic. anomaly in this way we can learn that which lineament zone should suggest an out cropped fault zone linear magnetic anomaly which has no corresponding lineament zone may suggest a buried fault zone.

Fig. 2 The magenetic anomaly-frequency distribution of some rocks

As to the recognition of rock types the first is the establishment of statistical model of magnetic anomaly frequency distribution in the area where rock types are known shows the magnetic anomaly frequency distribution model of some rocks. this model combined with field map data can be used for the rock recognition this cretaceous pull a part basin can be determine upon the spatial match between the faults and the andesites while major colcanic aparatuses and sub volcanic intrusions can be determined by circular features on TM images and on imaged magnetic anomaly field.

Effect of application
Through the integration analysis of remote sensing geologic aeromanetic and aeroadiometric data in image processing system we have determined the fault patterns and the volcanic basin distribution of the study area also we have determined the spatial distributions of radioactive anomalies as the regional geologic setting of uranium mineralization the sub surface geologic map was compiled.
Fig. 3 The subsurface Geological Map of the study area

This map helped much to uranium exploration in the vicinity of discovered deposit and according to the superposition model of geologic elements for the discovered uranium deposit fault zones controlling the intermediate basic and uranium anomalies fully over lap the study is believed to be a uranium region in which eight prospecting targets were for further exploration at one detailed interpretation air borne color infrared images scale 1 30 000 and side looking radar images at scale 1 :2 revealed the indications of the late Jurassic sub volcanic intrusion i depth the drilling followed and demonstrated its presence in depth 300m the uranium mineralization was seen at the contact of the intrusion with the host rhyolites.

References

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Wang Tianxi: Digitizing of Graphics and Its Application in processing of Remote Sensing imagery', Scientific Bulletin, Vol. 29, No. 18, 1983.
E.A Guiness et al: Digital image processing Applied to Analysis of Geophysical and Geochemical Data for Southern Missouri', Economic Geology, Vol. 78, No.4, 1983.