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The Genesis Of Chert And Its Relationship With The Formation Of Iron Deposit In The Ningwu Area

Posted on:2014-02-01Degree:MasterType:Thesis
Country:ChinaCandidate:J C ShenFull Text:PDF
GTID:2230330398966760Subject:Structural geology
Abstract/Summary:PDF Full Text Request
The cherts has a very wide distribution in Ningwu area,most associated with the Stratified Iron Deposits,and mainly divided into two types.The first type is the cherts of Jinglong-Longqi mountain area.Its have a extensive range of exposing area,closely associated with the Stratified hematite ores,and have a high degree of research.The views of its origin have volcanic-sedimentary origin and water-deposited origin.Another type is the cherts of Heshangyan area.Its exposing area is small,and have a thin iron ore layer at the top.The iron ore layer consists of magnetite and limonite,and did not reach the metallogenic scale,and have a low degree of research.The main purpose of this study is to reveal the differences of genetic environment and the relations of iron mineralization of the different types of cherts in Ningwu area.This paper expounded original types,material source and relations of iron mineralization of the different types of cherts in Ningwu area,using the analysis method of major elements, trace elements,REE and oxygen isotope.By this study and the results of previous studies,the following conclusions can be drawn:1.According to the geochemical characteristics of the major and trace elements of the samples in Jinglong-Longqi mountain area, it indicated a hydrothermal sedimentary origin.In Fe/Ti-Al/(A1+Fe+Mn) diagram,the samples in Heshangyan area shows that the samples are argillaceous siliceous rocks.The samples in Heshangyan area indicated a water-deposited origin in U-Th and Cr-Zr origin diagram.2.According to the primitive mantle normalized trace element patterns and REE disturbution patterns diagram,We can find that the samples in Jinglong-Longqi mountain area are very difference from regional volcano rock and upper crust.Indicator element ratios are lower than regional volcano rock and upper crust.In Th-Th/U diagram,the samples in Jinglong-Longqi mountain area all fall in the below the upper crust.High U and positive δEu in samples indicates that deep materials took part in the cherts,and have no relate with regional volcano rock in origin.We can find that the formation of the cherts in Heshangyan area is closely related to volcanism from some major elements diagram.The primitive mantle normalized trace element patterns and REE disturbution patterns diagram show that the samples in Heshangyan area are the same as regional volcano rock.The indicator element ratios of the samples in Heshangyan area and regional volcano rock are close.Its shows that material source of the cherts in Heshangyan area cameTrom regional volcano rock.Therefore,the formation of the cherts in Heshangyan area is closely related to regional volcano rock.3.The oxygen isotope compositions of the cherts in Jinglong-Longqi mountain area show that the deep magma source region which contributed to diagenesis of cherts may be original magma of late stage porphyrite.The rising deep hydrothermal fluid can dissolve and carry material of silica.The oxygen isotope compositions of the samples in Heshangyan area and iron ore layer above cherts are close.It can show that material of silica and mafic all came from regional volcano rock.The formation of material of silica and mafic is closely related to the rapid water-deposited of regional volcano rock.4.This study found no time-space relationship between the cherts in Jinglong-Longqi mountain area and porphyrite.The geochemical characteristics of the major and trace elements show that the material of cherts originate from deep source,may be from lower crust,not porphy rite. Its have a extensive range of exposing area and great potential for prospecting.But the cherts in Heshangyan area have a small range of exposing area and no potential for prospecting.
Keywords/Search Tags:Ningwu area, cherts, Iron ore deposit
PDF Full Text Request
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