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Min Qi - One of the best experts on this subject based on the ideXlab platform.
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geology and geochemistry of the macheng algoma type banded Iron formation north china craton constraints on mineralization events and genesis of high grade Iron Ores
Journal of Asian Earth Sciences, 2015Co-Authors: Huaying Wu, Lianchang Zhang, Franco Pirajno, Changle Wang, Min QiAbstract:Abstract The Macheng Iron deposit is located in the eastern Hebei province of the North China Craton (NCC). It is hosted in Neoarchean metamorphic rocks of Baimiaozi formation in the Dantazi Group, consisting of biotite-leptynite, plagioclase-gneiss, plagioclase-amphibolite, migmatite, migmatitic granite and quartz schist. Geochemical analyses of the host biotite leptynite and plagioclase amphibolites show that their protoliths are both volcanics, inferred to be trachytic basalt and basaltic andesite, respectively. Based on the geochemical signature of the host rocks, together with geology of the Iron deposit, it is inferred that the Macheng BIF is an Algoma-type Iron exhalative formation, formed in an arc-related basin in the Neoarchean. Post-Archean Australian Shale (PAAS)-normalized rare earth elements (REEs) plus yttrium (Y) concentrations of different BIF Ores with gneissic, striated and banded structure in the Macheng deposit, show similar patterns with depletions in light rare earth elements (LREEs) and middle rare earth elements (MREEs) relative to heavy rare earth elements (HREEs) and with apparently positive La, Y and Eu anomalies. Y/Ho ratios of the gneissic, striated and banded BIF Ores vary from 37 to 56. These geochemical features of the BIF Ores reveal their affinity with the sea water and the presence of a high-temperature hydrothermal component, indicating that both the seawater and high temperature hydrothermal fluids derived from alteration of oceanic basalts and komatiites may contribute to formation of the Macheng BIF. Geological, mineralogical and geochemical studies of the Macheng deposit recognized two kinds of high-grade Iron Ores. One is massive oxidized high-grade ore (Fe2O3T = 74.37–86.20 wt.%), mainly consisting of hematite with some magnetite, which shows geochemical characteristics of the gneissic, striated and banded BIF Ores. The other type is magnetite high-grade ore, also massive and consisting of magnetite, with distinct characteristics in trace elements of the gneissic, striated and banded BIF Ores but show similarity to those of the migmatitic Iron Ores with significantly negative Eu anomalies. The geochemical discrepancy or duality between the two types of high-grade Ores in Macheng suggests that they formed by two different mechanisms. One is related to supergene enrichment, caused by oxidation of magnetite and the leaching of gangue minerals from BIF to form high-grade ore. The other is probably related to intensive migmatization which produced high-grade Ores by altering the primary Iron Ores.
Changle Wang - One of the best experts on this subject based on the ideXlab platform.
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geology and geochemistry of the macheng algoma type banded Iron formation north china craton constraints on mineralization events and genesis of high grade Iron Ores
Journal of Asian Earth Sciences, 2015Co-Authors: Huaying Wu, Lianchang Zhang, Franco Pirajno, Changle Wang, Min QiAbstract:Abstract The Macheng Iron deposit is located in the eastern Hebei province of the North China Craton (NCC). It is hosted in Neoarchean metamorphic rocks of Baimiaozi formation in the Dantazi Group, consisting of biotite-leptynite, plagioclase-gneiss, plagioclase-amphibolite, migmatite, migmatitic granite and quartz schist. Geochemical analyses of the host biotite leptynite and plagioclase amphibolites show that their protoliths are both volcanics, inferred to be trachytic basalt and basaltic andesite, respectively. Based on the geochemical signature of the host rocks, together with geology of the Iron deposit, it is inferred that the Macheng BIF is an Algoma-type Iron exhalative formation, formed in an arc-related basin in the Neoarchean. Post-Archean Australian Shale (PAAS)-normalized rare earth elements (REEs) plus yttrium (Y) concentrations of different BIF Ores with gneissic, striated and banded structure in the Macheng deposit, show similar patterns with depletions in light rare earth elements (LREEs) and middle rare earth elements (MREEs) relative to heavy rare earth elements (HREEs) and with apparently positive La, Y and Eu anomalies. Y/Ho ratios of the gneissic, striated and banded BIF Ores vary from 37 to 56. These geochemical features of the BIF Ores reveal their affinity with the sea water and the presence of a high-temperature hydrothermal component, indicating that both the seawater and high temperature hydrothermal fluids derived from alteration of oceanic basalts and komatiites may contribute to formation of the Macheng BIF. Geological, mineralogical and geochemical studies of the Macheng deposit recognized two kinds of high-grade Iron Ores. One is massive oxidized high-grade ore (Fe2O3T = 74.37–86.20 wt.%), mainly consisting of hematite with some magnetite, which shows geochemical characteristics of the gneissic, striated and banded BIF Ores. The other type is magnetite high-grade ore, also massive and consisting of magnetite, with distinct characteristics in trace elements of the gneissic, striated and banded BIF Ores but show similarity to those of the migmatitic Iron Ores with significantly negative Eu anomalies. The geochemical discrepancy or duality between the two types of high-grade Ores in Macheng suggests that they formed by two different mechanisms. One is related to supergene enrichment, caused by oxidation of magnetite and the leaching of gangue minerals from BIF to form high-grade ore. The other is probably related to intensive migmatization which produced high-grade Ores by altering the primary Iron Ores.
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geochronology and geochemistry of the nanfen Iron deposit in the anshan benxi area north china craton implications for 2 55 ga crustal growth and the genesis of high grade Iron Ores
Precambrian Research, 2015Co-Authors: Mingtian Zhu, Lianchang Zhang, Changle Wang, Yanpei Dai, Li LiuAbstract:Abstract The Nanfen Iron deposit, situated in the Anshan-Benxi area of the North China Craton (NCC), hosts scattered banded Iron formations (BIFs) and BIF-hosted high-grade Iron orebodies (defined by FeOT > 80 wt.%). The associated roof and bottom rocks, which occur in parallel to orebodies, are mica quartz schist and chlorite hornblende schist (locally interlayers), respectively. The PAAS-normalized rare earth element (REE) patterns indicate that quartz–magnetite banded Iron formations (BIFs) are enriched in Heavy REEs with positive La, Eu and Y anomalies, indicating that the Nanfen BIF precipitated from a mixture of ambient seawater and submarine high-T hydrothermal fluids (∼0.1%). In addition, the BIF exhibits low concentrations of Al2O3 and TiO2 with depletion in HFSEs (high field strength elements, e.g., Nb, Ta, Zr, Hf and Ti), suggesting little contamination with continental detritus. Excepting lower Eu/Eu* values, the high-grade Iron Ores display similar geochemical features to the BIF, likely implying that they have a same Iron source but did not form synchronously. Electron microprobe analyses (EMPA) and in situ LA-ICP-MS analyses reveal that in relative to the magnetite grains in high-grade Ores, the magnetite grains in the BIF contain higher MnO, MgO and Zn concentrations, and lower Al2O3 and REE abundances, implying different formation conditions. Thus, we argue that high-grade Ores are likely to be alteration products of primary BIFs. Chlorite hornblende schist (meta-basalt) samples exhibit low SiO2 contents (43.78–50.30 wt.%) with flat chondrite-normalized REE and N-MORB-normalized trace element patterns, which are similar to those of BABB (back-arc basin basalt). The zircon U–Pb dating results indicate that magmatic and metamorphic zircons from chlorite hornblende schist formed at approximately 2552 Ma and 2482 Ma, respectively. The former volcanic age could constrain the deposition age of the Nanfen BIF, and the latter reflects a subsequent metamorphic event, which is also reflected by the ∼2480 Ma hydrothermal zircons selected from the BIF. Moreover, most zircons from chlorite hornblende schist have positive ɛHf(t) values (0.22–7.96) close to the depleted mantle evolutionary curve, implying that the source magma were derived from a depleted mantle with some contamination from ancient crust. Hence, we propose that the Nanfen BIF is a Neoarchean Algoma-type BIF, and its deposition was most likely benefited due to crustal growth.
Lianchang Zhang - One of the best experts on this subject based on the ideXlab platform.
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geology and geochemistry of the macheng algoma type banded Iron formation north china craton constraints on mineralization events and genesis of high grade Iron Ores
Journal of Asian Earth Sciences, 2015Co-Authors: Huaying Wu, Lianchang Zhang, Franco Pirajno, Changle Wang, Min QiAbstract:Abstract The Macheng Iron deposit is located in the eastern Hebei province of the North China Craton (NCC). It is hosted in Neoarchean metamorphic rocks of Baimiaozi formation in the Dantazi Group, consisting of biotite-leptynite, plagioclase-gneiss, plagioclase-amphibolite, migmatite, migmatitic granite and quartz schist. Geochemical analyses of the host biotite leptynite and plagioclase amphibolites show that their protoliths are both volcanics, inferred to be trachytic basalt and basaltic andesite, respectively. Based on the geochemical signature of the host rocks, together with geology of the Iron deposit, it is inferred that the Macheng BIF is an Algoma-type Iron exhalative formation, formed in an arc-related basin in the Neoarchean. Post-Archean Australian Shale (PAAS)-normalized rare earth elements (REEs) plus yttrium (Y) concentrations of different BIF Ores with gneissic, striated and banded structure in the Macheng deposit, show similar patterns with depletions in light rare earth elements (LREEs) and middle rare earth elements (MREEs) relative to heavy rare earth elements (HREEs) and with apparently positive La, Y and Eu anomalies. Y/Ho ratios of the gneissic, striated and banded BIF Ores vary from 37 to 56. These geochemical features of the BIF Ores reveal their affinity with the sea water and the presence of a high-temperature hydrothermal component, indicating that both the seawater and high temperature hydrothermal fluids derived from alteration of oceanic basalts and komatiites may contribute to formation of the Macheng BIF. Geological, mineralogical and geochemical studies of the Macheng deposit recognized two kinds of high-grade Iron Ores. One is massive oxidized high-grade ore (Fe2O3T = 74.37–86.20 wt.%), mainly consisting of hematite with some magnetite, which shows geochemical characteristics of the gneissic, striated and banded BIF Ores. The other type is magnetite high-grade ore, also massive and consisting of magnetite, with distinct characteristics in trace elements of the gneissic, striated and banded BIF Ores but show similarity to those of the migmatitic Iron Ores with significantly negative Eu anomalies. The geochemical discrepancy or duality between the two types of high-grade Ores in Macheng suggests that they formed by two different mechanisms. One is related to supergene enrichment, caused by oxidation of magnetite and the leaching of gangue minerals from BIF to form high-grade ore. The other is probably related to intensive migmatization which produced high-grade Ores by altering the primary Iron Ores.
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geochronology and geochemistry of the nanfen Iron deposit in the anshan benxi area north china craton implications for 2 55 ga crustal growth and the genesis of high grade Iron Ores
Precambrian Research, 2015Co-Authors: Mingtian Zhu, Lianchang Zhang, Changle Wang, Yanpei Dai, Li LiuAbstract:Abstract The Nanfen Iron deposit, situated in the Anshan-Benxi area of the North China Craton (NCC), hosts scattered banded Iron formations (BIFs) and BIF-hosted high-grade Iron orebodies (defined by FeOT > 80 wt.%). The associated roof and bottom rocks, which occur in parallel to orebodies, are mica quartz schist and chlorite hornblende schist (locally interlayers), respectively. The PAAS-normalized rare earth element (REE) patterns indicate that quartz–magnetite banded Iron formations (BIFs) are enriched in Heavy REEs with positive La, Eu and Y anomalies, indicating that the Nanfen BIF precipitated from a mixture of ambient seawater and submarine high-T hydrothermal fluids (∼0.1%). In addition, the BIF exhibits low concentrations of Al2O3 and TiO2 with depletion in HFSEs (high field strength elements, e.g., Nb, Ta, Zr, Hf and Ti), suggesting little contamination with continental detritus. Excepting lower Eu/Eu* values, the high-grade Iron Ores display similar geochemical features to the BIF, likely implying that they have a same Iron source but did not form synchronously. Electron microprobe analyses (EMPA) and in situ LA-ICP-MS analyses reveal that in relative to the magnetite grains in high-grade Ores, the magnetite grains in the BIF contain higher MnO, MgO and Zn concentrations, and lower Al2O3 and REE abundances, implying different formation conditions. Thus, we argue that high-grade Ores are likely to be alteration products of primary BIFs. Chlorite hornblende schist (meta-basalt) samples exhibit low SiO2 contents (43.78–50.30 wt.%) with flat chondrite-normalized REE and N-MORB-normalized trace element patterns, which are similar to those of BABB (back-arc basin basalt). The zircon U–Pb dating results indicate that magmatic and metamorphic zircons from chlorite hornblende schist formed at approximately 2552 Ma and 2482 Ma, respectively. The former volcanic age could constrain the deposition age of the Nanfen BIF, and the latter reflects a subsequent metamorphic event, which is also reflected by the ∼2480 Ma hydrothermal zircons selected from the BIF. Moreover, most zircons from chlorite hornblende schist have positive ɛHf(t) values (0.22–7.96) close to the depleted mantle evolutionary curve, implying that the source magma were derived from a depleted mantle with some contamination from ancient crust. Hence, we propose that the Nanfen BIF is a Neoarchean Algoma-type BIF, and its deposition was most likely benefited due to crustal growth.
S Sanjeevi - One of the best experts on this subject based on the ideXlab platform.
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hyperion image analysis and linear spectral unmixing to evaluate the grades of Iron Ores in parts of noamundi eastern india
International Journal of Applied Earth Observation and Geoinformation, 2014Co-Authors: T Magendran, S SanjeeviAbstract:Abstract This paper reports the results of a study to differentiate Iron Ores in terms of their grades, using the hyperspectral (EO-1 Hyperion) image data, covering a mineralized belt in the Noamundi area, eastern India. The study involves hyperspectral data collection, pre-processing (reduction of atmospheric and solar flux effects), generation of spectral curves from the image for the Iron ore deposits, extraction of key spectral parameters and linear spectral unmixing for mapping Iron ore abundance. Spectral curves for Iron ore deposits extracted from the Hyperion image pixels exhibit strong absorption at 850–900 nm and 2150–2250 nm wavelengths, which is typical of Iron Ores. The strength of the absorption features in the continuum removed spectra varies spatially in the image around the mining areas, indicating differences in composition/grade of the Iron Ores. Spectral parameters such as the depth, width, area and wavelength position of the absorption features, derived from image spectra in the 850–900 nm and 2150–2250 nm regions, correlate well with the concentration of Iron-oxide and alumina (gangue) in the ore samples obtained from the mine face. Well defined correlations are evident between the concentration of Iron oxide and (i) the depth of NIR absorption feature ( R 2 = 0.883); (ii) the width of NIR absorption feature ( R 2 = 0.912); and (iii) the area of the NIR absorption feature and ( R 2 = 0.882). Further, the linear spectral unmixing resulted in an Iron ore abundance map which, in conjunction with the image- and laboratory-spectra, helped in assessing the grades of Iron Ores in the study area. Thus, this study demonstrates the feasibility of discriminating grades of Iron Ores based on spectral information derived from spaceborne hyperspectral imagery.
Xiaoyong Yang - One of the best experts on this subject based on the ideXlab platform.
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geochemical constraints on the genesis of the algoma type banded Iron formation bif in yishui county western shandong province north china craton
Ore Geology Reviews, 2017Co-Authors: Inkyeong Moon, Xiaoyong YangAbstract:Abstract The Yishui Iron deposit is a typical Algoma-type banded Iron formation (BIF) located in Yishui County, Taishan Group, Shandong Province in the Eastern Block (EB) of the North China Craton (NCC). The BIF is interlayered with amphibolite, migmatitic granite, gneiss, and schist. Integrated petrological, mineralogical, and geochemical interpretations of the Iron Ores were used to reconstruct the genesis of the Yishui BIFs and their tectonic evolution. The Iron ore samples were collected from surface outcrops. Banding textures are not always present in the Iron Ores because the BIF experienced complex high-grade metamorphism after precipitation. Interpretations of the major elements and rare earth elements plus yttrium (REY) data of the Iron Ores suggests that the ore-forming materials of the Yishui BIF precipitated from a mixture of seawater and high-temperature hydrothermal fluids ( 2 and Fe 2 O 3 T (SiO 2 + Fe 2 O 3 T = 85.8–95.8 wt%) are consistent with the major minerals, such as quartz and Iron oxide, which represent chemical precipitates. Chlorite, amphibole, plagioclase, biotite, and calcite are present as minor minerals. The low contents of TiO 2 (0.01–0.09 wt%), Al 2 O 3 (0.42–1.18 wt%), and high field strength elements (HFSEs) indicate little to no detrital assimilation, which implies that the Iron Ores preserved their original geochemical signatures. Based on geochemical interpretations, we conclude that the Yishui BIF can be explained by a mantle plume model that describes not only the tectonic evolution but also the sources of Iron and silica of the Yishui BIF.