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Sijiaying |
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Hebei, China |
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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 Sijiaying iron deposit is located in the Yanshan Mountains, some 20 to 30 km from Tangshan City, Hebei Province, 150 km ESE of Beijing in north-eastern China (#Location: 39°: 40' 30"N, 118° 45' 25"E).
The ore deposits are hosted by banded iron formation (BIF) of the 2.6 to 2.4 Ga Neoarchaean to Paleoproterozoic Dantazi Group within the north-eastern North China Craton. These deposits are part of the larger 300x50 km Jidong Metallogenic Belt of North China that hosts other BIF and gold deposits.
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 (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).
The Dantazi Group and BIFs it hosts occur on the western margin of the Eastern Archaean Block, deposited on the 2.55 to 2.50 Ma Quinglong foreland basin (Kusky and Jianghai, 2003).
The Dantazi Group are Archaean amphibolite facies metamorphic derived from mafic volcanic lava, felsic volcanic greywacke, felsic volcanic greywacke and carbonates that formed in a marine basin. The BIF belt in the district is 25 km long and trends north-south.
The Sijiaying deposit occurs in a gently-dipping anticline and adjacent syncline within a 25 km long, north-south trending belt of BIF and comprises multiple concordant units of BIF within host biotite microgneiss, K-feldspar microgneiss and minor intercalated amphibolite, quartzite and marble.
Within the ore deposit, Fe minerals mainly occur as laminated with lesser coarsely banded and massive fine-grained magnetite and quartz. Some parts of the deposit are composed of hematite, with minor actinolite, tremolite, amphibole and sulphides.
Published resource figures include:
2200 Mt @ 30% Fe, and locally up to 50% Fe - Total resource (Rodionov, et al., 2004, USGS Open File Rept. 2002).
884 Mt @ 29.2%, Proven industrial ores reserves (Tangshan Iron and Steel website, 2007).
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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