bayan obo mine aktie

Radiometric ages of minerals in sample 796-48,277: A, Internal isochron showing mineral age of the monazite (4328.5 Ma), which replaced the host limestone marble and occurs as abundant inclusions in alkali amphibole; B, 40Ar/39Ar plateau showing age (343.13.0 Ma) of the coexisting alkali amphibole that replaced the monazite. Meng and Drew (1992) reported new data on stable oxygen and carbon isotopes from six selected samples of relict micrite (very fine grained carbonate rock) from the H8 dolostone marble. The mines north of town are one the largest deposits of rare earth metals... Get premium, high resolution news photos at Getty Images 2) is separated from the area to the north by a major fault zone, the Kuanggou fault. Monazite from sample 490,330 (fig. An absolute mineral paragenetic sequence can be partially established on the basis of absolute ages of episodes of REE mineralization and the unique chemical compositions and isotopic ratios of the different generations of REE minerals. The occurrence of post-Caledonian or late Caledonian or early Hercynian low-grade regional metamorphism was also needed to account for the widespread presence of microchevron folds in banded ores and the recrystallized triple-junction grain boundary textures observed in some of the very fine grained REE and gangue minerals (apatite, barite, and fluorite) within bands of the banded ores. These banded ores consist of prominent bands containing abundant monazite and bastnaesite. Late-stage fluorite and barite also occur as veinlets cutting banded ores. Throughout the outcrop area (fig. The H8 unit consists chiefly of dolostone marble but has subordinate limestone marble; interbeds of quartzite and feldspathic quartzite are present throughout the unit but are most prevalent in the upper and lower parts. Baiyun'ebo or Bayan Obo is a mining town in Inner Mongolia in China. Seite 2623 der Diskussion 'Aktien, Gold und Rohstoffe , Währungen und Anleihen - was bewegt die Welt heute?' Zhang and Tao (1986) recognized two stages of Hercynian granite rocks; biotite ages show the early stage of 311-306 Ma and the later stage of 258-234 Ma. Die Erzgruben wurden … Precise internal isochron mineral ages of monazites and bastnaesites were determined by the 232Th/208Pb method in USGS laboratories in Denver, Colo. The Bayan Obo mine area is about 100 km south of the suture marking Caledonian subduction (fig. percent F. The Caledonian regional metamorphic event began at about 425 Ma and continued until at least 395 Ma, based on 40Ar/39Ar ages of amphiboles. Of these, sample 7B25-1C is coarse-grained dolomite marble; 7B36-10C is coarse-grained ferroan dolomite embedded in a fine-grained ferroan dolomite "matrix" (7B36-10F); and 7B34-15C is coarse-grained ferroan dolomite surrounded by fine-grained ferroan dolomite, 7B34-15F, of the same sample. Figure 19. In the summers of 1988 and 1990, the preliminary mineral paragenetic sequences established petrographically from doubly polished thin sections (DPTS's) were checked in the field to confirm consistencies with field relations. The total RE Die oft verwendete abgekürzte Bezeichnung Seltene Erden statt Metalle der Seltenen Erden ist missverständlich. The largest REE mine in the world, Bayan Obo, alone provides 40-50% of all REEs. Samples collected in 1987, 1988, and 1990 are numbered with a prefix 7B, 8B, and 9B, respectively, followed by the sample location number. Table 3. The dominant REE mineral is bastnaesite, but lesser amounts of cebaite also are present. The Bayan Obo ore deposit is a famous, world‐class, giant Nb‐REE‐Fe deposit located in Inner Mongolia, China, situated approximately 80 km south of the border between China and Mongolia, at 109°57’E and 41°46’N. percent. Principal minerals of the Bayan Obo ore deposit. bei Silver Wheaton, einer Edelmetall Aktie . percent), whereas fluorite is reflected by the Ca and F contents (CaO ranges from 2.94 to 37.78 wt. This section was subsequently described in greater detail by Chao and others (1992). Because of the large amounts of alkali amphiboles present, particularly the asbestiform variety, we interpret this mineral occurrence to be of metasomatic-metamorphic origin. Two pieces of evidence suggest that the 232Th/208 Pb data are reliable: (1) all of the monazite and bastnaesite samples submitted yielded good internal isochrons, so that none were rejected; and (2) the internal isochron ages of two splits of monazite sample 796-48,278, submitted 3 months apart to the USGS Denver laboratory, are 422+-16 and 415+-8 Ma, respectively, their combined internal isochron age being 419+-3.7 Ma (fig. Bayan Obo Mine in der Inneren Mongolei, China Die Bayan Obo Mine beherbergt eines der weltweit größten Vorkommen an seltenen Erden. Similarly, for a sample containing aegirine augite, the total is low because neither SiO2 nor Na2O was determined. High-REE and low-Fe and low-F banded ores (table 10). Because of the good to excellent plateau release patterns of Caledonian-age alkali amphiboles, these alkali amphiboles do not appear to have been seriously affected by thermal events associated with the intrusion of granitic rocks or regional metamorphic events of Hercynian age. c. Marble with disseminated granular hematite, with or without small amounts of magnetite (samples 7B36-12 and 9B4), and with or without gangue minerals such as fluorite and barite. Bastnaesite-apatite-aegirine augite-fluorite+-martite banded ores (table 8). 3). On the basis of the presence of alkali amphiboles of metamorphic origin, the degree of metamorphism during the Late Proterozoic and Caledonian events was probably equivalent to low-grade amphibolite facies. Cerianite, an alteration product (Zhang and Tao, 1986), is bright red in hand specimen, is red and isotropic in DPTS, and is the only Bayan Obo mineral radioactive enough to require shielding and caution in handling of samples that contain it. The functional unit of the investigation is therefore “1 kg Nd” and “1 kg Dy”, respectively. The uppermost H9 unit of the Bayan Obo Group, which is the cap rock of the Bayan Obo orebodies, consists of dark-gray to black shale, slate, biotite schist, and albitized biotite schist. 2) is separated from the area to the north by a major fault zone, the Kuanggou fault. Figure 28. percent total RE2O3 (tables 6-9). The other sulfides are late-stage minerals that occur in some disseminated ores and in small amounts in banded ores. Detrital albite grains also occur in feldspathic quartzite, and albite porphyroblasts are found in albitized biotite schist. These are (1) euhedral martite or martitized magnetite grains scattered in disseminated ores, in scattered aggregates in bands of banded ores, and in massive ores; (2) fine-grained to very fine grained primary granular hematite that forms disseminated patches and scattered lenses in dolostone marble disseminated ores and in bands in banded ores, and also occurs in massive ores; and (3) nonmartitized magnetite in disseminated, banded, and massive ores. Known as the "hometown of rare earth", it is also the main raw materials base of Baogang Group. Marble-hosted alkali amphibole-magnetite banded ores (table 11). Scattered prismatic alkali amphiboles of metamorphic origin are present in the dolostone marble, where they are most abundant along foliation planes. The Bayan Obo mining area is shown in Figure 1. Table 8. Geologically, the Bayan Obo region (Fig. Baiyun'ebo or Bayan Obo is a mining town in Inner Mongolia in China. Bayan Obo ore deposit is the largest rare-earth element (REE) resource, and the second largest niobium (Nb) resource in the world. Embed. The bands of granular apatite visible in the corresponding DPTS's are not reflected in the analyses because P2O5 concentrations were not determined. The largest REE mine in the world, Bayan Obo, alone provides 40-50% of all REEs. z.B. 5, and 7B36-1B), with or without fluorite. BaO, SrO, Ce2O3, La2O3, Nd2O3, and Nb2O5 contents of unmineralized and REE-mineralized H8 dolostone marble were determined by inductively coupled plasma-mass spectrometry (ICP-MS). Photomicrograph of a doubly polished thin section of sample 8B2-2 showing euhedral martitized magnetite crystals blocking the continuous formation of later fine-grained hematite. Therefore, we conclude that the REE's in unmineralized Bayan Obo dolostone marble are present only in detrital apatite and that RE2O3 contents greater than about 800 ppm in fine-grained dolostone marble are due to weak epigenetic mineralization. percent) of high-Fe, REE, and fluorite banded ores of Bayan Obo. Paleotectonic map of northern China in the Caledonian period (modified from Wang, 1985), showing locations of the Caledonian subduction, the Hercynian subduction, and the Caledonian Hejao anorogenic granites. Table 7. Approximately 75 m3 (2,600 cu ft) of acidic wastewater, plus about a ton of radioactive waste residue are also produced.[4]. 6), and rounded detrital apatite grains are present in the coarser grained marble (fig. 3. High-Fe, REE, and fluorite banded ores (table 9). 4. percent FeO. West Mine, Bayan Obo deposit (Bayun-Obo deposit; Baiyunebo deposit), Bayan Obo, Bayan Obo mining district, Baotou City (Baotou Prefecture), Inner Mongolia, China Bayan Obo deposit (Bayun-Obo deposit; Baiyunebo deposit), Bayan Obo, Bayan Obo mining district, Baotou City (Baotou Prefecture), Inner Mongolia, China . (Image credit: NASA Earth Observatory) The mining is not without shortcomings. percent F in the samples. In addition to the widespread occurrence of Hercynian biotite granites and granodiorites in the Bayan Obo region, evidence for the Hercynian regional metamorphism is based on 40Ar/39Ar single-grain total-fusion analyses of biotite from H9 biotite schist, which was reset and yielded ages ranging from 309.8+-5.8 to 297.1+-5.2 Ma. In 2009 China produced 95% of the world's supply of these elements, and it's estimated that the Bayan Obo mines just north of Baotou contain 70% of … Sample locations are shown in figure 5. Monazite and alkali amphiboles are replaced and cut by fresh magnetite. The Bayan Obo mine area (fig. Nevertheless, the general mineral assemblage of the DPTS does reflect the chemical composition qualitatively. This method is preferred over other methods because precise ages are obtained on the basis of actual measurements of Th and Pb, rather than by assuming initial Pb concentrations. percent, occurring as granular hematite) and REE's (total RE2O3 is 8.28 wt. percent, the highest reported), and a moderately high 208Pb/204Pb initial ratio (39.76+-2.06). The internal isochron mineral ages of episodes of monazite and bastnaesite mineralization are shown in table 14 and figures 18-22, 32, and 33. Small amounts of porphyroblastic albite biotite schist and biotite-rich minette occur as lenses within this unit. Internal isochrons of monazite from two samples (7B36-6 and 8B35-2) of Bayan Obo ores that show nearly identical 208Pb/204Pb initial ratios indicate different internal isochron ages, suggesting a common source reservoir that was tapped at different times. percent and F ranges from 1.02 to 16.0 wt. The chemical compositions and internal isochron ages of monazites and bastnaesites are given in table 14, arranged according to internal isochron ages. Lanthanum, for … 19), with an internal isochron mineral age of 431+-2.7 Ma, has the lowest 208Pb/204Pb initial ratio (32.47+-0.17) and is the most primitive, least radiogenic sample. Because of the high contents of combined F, Fe, and REE's in many of the ore types, only partial analyses of ore samples could be obtained by the ICP-AES method, which did not analyze for SiO2, Na2O, CO2, or in most cases, P2O Many of the more strongly mineralized zones in the orebodies follow the east-trending shear zones. Additionally, concentrations of gallium can be found in bauxite, a sedimentary rock typically mined for aluminium. 33), are as old as 890 Ma (samples 40-14 and 8B24-1, table 15). REE minerals were discovered in 1936, and niobium -bearing ores in the late 1950s. The significance is questionable of the Pb-Pb and Sm-Nd model ages of 1400-1500 Ma that were used by previous investigators to estimate the age of the H8 (Chao and others, 1992; Conrad and McKee, 1992; Wang and others, 1994). A small swarm of 11 calcitic carbonatite dikes, mostly 1-2 m wide and up to 150 m long, cut across an anticlinal structure in the Archean Wutai granitic gneisses and migmatites, approximately 1.5 km northeast of the mine area. Very large rare-earth elements (REE) Fe-Nb deposit (Bayan-Obo type), discovered as an iron deposit in 1927. Massive Fe ores consist principally of at least one of the Fe-oxide minerals granular hematite, martite, and magnetite (fig. Effect of existence form of La3+ on the properties of the Bayan Obo Mine tailing glass ceramics. Because of the high contents of combined F, Fe, and REE's, inductively coupled plasma-atomic emission spectrometry (ICP-AES) was used for partial analysis of most of the disseminated and banded ores. Fine- to medium-grained bastnaesite also occurs in late-stage ore dominated by aegirine and aegirine augite, where it is associated with apatite and barite. 5; therefore, low analytical totals are reported in tables 6-12. In thin section, quartzite shows triple-junction grain boundaries; in highly sheared parts, the grains are stretched, having a width-to-length ratio of from 1:5 to more than 1:10. A minimum age of the H8 marble also is indicated by the 40Ar/39Ar ages of alkali amphiboles occurring along foliation planes in the marble, which in spite of varying degrees of argon loss indicated by age spectrum and total fusion analyses (fig. percent Fe2O3) in this sample, and monazite and bastnaesite account for the total RE2O3 present (10.89-22.36 wt. percent) of selected monazite (bastnaesite)-fluorite (low-Fe, high-REE) banded ores of Bayan Obo. percent). A sample of K-feldspar from a pegmatite dike crosscutting H9 biotite schist gave a K-Ar age of 225+-7 Ma. b. Aegirine-magnetite banded ore, with or without bastnaesite and monazite (sample 7B30-43). Clearly, the episodes of magnetite and Nb mineralization and the range of Hercynian regional metamorphism are complex and require more detailed study. The minimum age of this event of regional metamorphism, based on single-grain, laser total-fusion 40Ar/39Ar analyses of lineated magnesio-arfvedsonite prismatic crystals in coarse-grained H8 dolostone marble (samples 40-14 and 8B24-1, table 15) is about 890 Ma. percent) (table 14), which are low for La2O3 and uniquely high for Nd2O3 at Bayan Obo. The total values in table 12 are low because SiO2 contents of the host quartzite and silicate gangue minerals were not determined by the ICP-AES method of analysis. percent), a high Nd2O3 content (10.90 wt. a. Bastnaesite-granular hematite-fluorite banded ore with or without minor granular aegirine (samples 7B30-39, 7B30-40, 7B30-41A, and 7B30-41B).

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