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Yuanjiachun |
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Shanxi, 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 Yuanjiachun iron deposit is located some 100 km north-west of Tiayan City in the Luliangshan Mountains of central-western Shanxi Province, north-eastern China (#Location: 38° 15' 10"N, 111° 27' 48"E).
The deposit lies within the 200 x 40 to 60 km Luliangshan Metallogenic Belt, hosted by the Paleoproterozoic Luliang Group, part of the overlap assemblage above the Archaean Liaoning-Hebei-Shanxi terrane on the northern margin of the North China 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).
The Paleoproterozoic overlap assemblage on the northern margin of the North China craton, including the Hutuo and Luliang Groups, comprises the following geological units, from the base: i). metaconglomerate, quartzite, feldspar quartzite, phyllite and dolomite; ii). phyllite, dolomite, sandy slate and quartzite intercalated with metabasalt (U-Pb zircon isotopic age of 2.366 Ga); and iii). metaconglomerate, phyllite, plagioclase-quartzite, and quartzite.
The banded iron formations (BIFs) of the overlap assemblage are associated with metamorphosed clastic rocks and marble units. Both the host succession and the BIFs have been folded, sheared and regionally metamorphosed to greenschist facies. The Luliang Group is interpreted to have been desposited in a second-order basin within a rift zone, along the craton margin.
The individual BIF units at Yuanjiachun strike north-south for several to more than 10 km and are developed over a stratigraphic width of 300 m. They are concordant with the local host sequence that consists of clastic rocks, mudstone, carbonates and minor volcanic rocks that has been metamorphosed to greenschist facies. The BIFs are mainly composed of specularite, hematite, magnetite, quartz, cummingtonite and stilpnomelanewithin a gangue of silicate and carbonate rocks with laminated and striped textures.
Reserves of 895 Mt @ 32.37% Fe have been quoted (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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