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Zhalanzhangzhi |
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Hebei, China |
| Main commodities:
Fe
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Super Porphyry Cu and Au
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IOCG Deposits - 70 papers
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All papers now Open Access.
Available as Full Text for direct download or on request. |
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The Zhalanzhangzhi iron deposit is located some 180 km north-east of Beijing in eastern Hebei Province, north-eastern China (#Location: 40° 19' 40"N, 119° 22' 10"E).
The deposit lies within the 80 x 30 km Qinlong Metallogenic Belt which coincides with a Paleoproterozoic belt of marine volcaniclastic and sedimentary rocks with minor conglomerate, interpreted as representing a passive continental margin or aulacogen on the northern margin of the North China craton that has subsequently been metamorphosed to greenschist and amphibolite facies and thrust over the craton.
The North China Craton is composed of the two older, north-south elongated, Eastern and Western Archaean Blocks, separated by a Central Orogenic Belt. It has been interpreted that the Eastern and Western Blocks collided at 2.5 Ga during an arc/continent collision, forming a foreland basin over the Eastern Block (the Quinglong foreland basin), a granulite facies belt on the western block, and a wide orogen between the two blocks. This was followed by post-orogenic extension and rifting, simultaneous with the development of a major ocean lapping onto the northern margin of the craton during the early Paleoproterozoic (Kusky and Jianghai, 2003).
A magmatic arc terrane, which is indicated to have developed in this ocean and was elongated east-west parallel to the northern margin of the craton, collided with that northern craton margin by 2.3 Ga, to form a 1400 km long orogen known as the Inner Mongolia-Northern Hebei Orogen. A 1600 km long granulite-facies terrane formed on the southern margin of this orogen, representing a 200 km wide uplifted plateau as a result of crustal thickening. This granulite facies terrane comprises a southern belt of reworked Archaean basement and a northern metamorphosed accretionary belt. To the south of this granulite terrane, the Archaean sequences have mainly been subjected to amphibolite facies matamorphism. The orogen was converted to an Andean-style convergent margin from 2.20 to 1.85 Ga, reflected by belts of plutonic rocks, accreted metasedimentary rocks, and a possible back-arc basin. A pulse of convergent deformation is recorded at 1.9 to 1.85 Ga across the northern margin of the craton (Kusky and Jianghai, 2003).
Banded iron formation (BIF) units within the Qinlong Metallogenic Belt are within the Paleoproterozoic Zhuzhangzi Group, intercalated with tourmaline microgneiss and garnet-mica schist. The Zhuzhangzi Group is believed to represent a metamorphosed sequence of clastic sedimentary rock and carbonates with lesser intercalated mafic- and more abundant felsic-volcanic rocks.
At Zhalanzhangzhi the main BIF unit is concordant, 10 to 30 m thick and has a strike extent of 2000 m. The deposit is localised in the core and adjacent limbs of an asymmetric fold and dips at between 60 and 70°. The BIFs are principally composed of magnetite, quartz, actinolite, tremolite and cummingtonite, with minor calcite, garnet, biotite and pyrite and have a grain size of about 0.05 mm.
The published reserve is 200 Mt @ 29.06% Fe. Some sections of the ore contain "high" sulphur (Rodionov, et al., 2004, USGS Open File Rept. 2002).
The most recent source geological information used to prepare this decription was dated: 2006.
This description is a summary from published sources, the chief of which are listed below.
© Copyright Porter GeoConsultancy Pty Ltd. Unauthorised copying, reproduction, storage or dissemination prohibited.
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Porter GeoConsultancy Pty Ltd (PorterGeo) provides access to this database at no charge. It is largely based on scientific papers and reports in the public domain, and was current when the sources consulted were published. While PorterGeo endeavour to ensure the information was accurate at the time of compilation and subsequent updating, PorterGeo, its employees and servants: i). do not warrant, or make any representation regarding the use, or results of the use of the information contained herein as to its correctness, accuracy, currency, or otherwise; and ii). expressly disclaim all liability or responsibility to any person using the information or conclusions contained herein.
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