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1.
The geochemical features of typical representatives of ferromanganese deposits are studied in the eastern Bureya and Khanka massifs (Russian Far East). Based on the major-, trace-, and rare-earth element distribution, the hydrothermal–sedimentary (with hydrogenic component) nature of their mineralization is established and the geodynamic setting and depth of ore formation are estimated. The differences in the depth and redox conditions of ore formation resulted in the metallogenic zonation of the Khingan block (Bureya Massif), which is expressed in a westward change in ore composition from the magnetite ores of the Kosten’ga–Kimkan zone to the hematite–magnetite and iron–manganese ores of the South Khingan zone. The conclusions about the participation of hydrothermal sources in the formation of ore mineralization of the studied deposits and the specifics of their localization require revision of the strategy of exploration and evaluation of ferromanganese ores in the southern Far East. 相似文献
2.
Takeru Moriyama Mruganka K. Panigrahi Dinesh Pandit Yasushi Watanabe 《Resource Geology》2008,58(4):402-413
The major, trace and rare earth element (REE) composition of Late Archean manganese, ferromanganese and iron ores from the Iron Ore Group (IOG) in Orissa, east India, was examined. Manganese deposits, occurring above the iron formations of the IOG, display massive, rhythmically laminated or botryoidal textures. The ores are composed primarily of iron and manganese, and are low in other major and trace elements such as SiO2, Al2O3, P2O5 and Zr. The total REE concentration is as high as 975 ppm in manganese ores, whereas concentrations as high as 345 ppm and 211 ppm are found in ferromanganese and iron ores, respectively. Heavy REE (HREE) enrichments, negative Ce anomalies and positive Eu anomalies were observed in post‐Archean average shale (PAAS)‐normalized REE patterns of the IOG manganese and ferromanganese ores. The stratiform or stratabound shapes of ore bodies within the shale horizon, and REE geochemistry, suggest that the manganese and ferromanganese ores of the IOG were formed by iron and/or manganese precipitation from a submarine, hydrothermal solution under oxic conditions that occurred as a result of mixing with oxic seawater. While HREE concentrations in the Late Archean manganese and ferromanganese ores in the IOG are slightly less than those of the Phanerozoic ferromanganese ores in Japan, HREE resources in the IOG manganese deposits appear to be two orders of magnitude higher because of the large size of the deposits. Although a reliable, economic concentration technique for HREE from manganese and ferromanganese ores has not yet been developed, those ores could be an important future source of HREE. 相似文献
3.
I. V. Kubrakova I. Ya. Koshcheeva O. A. Tyutyunnik A. M. Asavin 《Geochemistry International》2010,48(7):655-663
In order to elucidate possible processes leading to platinum accumulation in ferromanganese deposits, we analyzed published
data on the interaction of dissolved platinum species in different valence states with iron and manganese oxyhydroxides under
oceanic conditions and experimentally studied the kinetics of sorption of inorganic and organic complexes of platinum (II)
and platinum (IV) on synthetic iron and manganese oxyhydroxides and natural materials (marine colloids, and ferromanganese
crust samples). The role of dissolved and suspended particulate aquatic organic matter in the sorption accumulation of platinum
was evaluated. Possible reasons for the preferential (compared with other noble metals) accumulation of platinum in oceanic
ferromanganese deposits were discussed. 相似文献
4.
Rare Earth, Major and Trace Elements in the Kunimiyama Ferromanganese Deposit in the Northern Chichibu Belt, Central Shikoku, Japan 总被引：1，自引：0，他引：1
Yasuhiro Kato Koichiro Fujinaga Tatsuo Nozaki Kentaro Nakamura Ryuji Ono Hiroshi Osawa 《Resource Geology》2005,55(4):291-300
Abstract. Rare earth, major and trace element geochemistry is reported for the Kunimiyama stratiform ferromanganese deposit in the Northern Chichibu Belt, central Shikoku, Japan. The deposit immediately overlies greenstones of mid-ocean ridge basalt (MORB) origin and underlies red chert. The ferromanganese ores exhibit remarkable enrichments in Fe, Mn, P, V, Co, Ni, Zn, Y and rare earth elements (excepting Ce) relative to continental crustal abundance. These enriched elements/ Fe ratios and Post-Archean Average Australian Shale-normalized REE patterns of the ferromanganese ores are generally analogous to those of modern hydrothermal ferromanganese plume fall-out precipitates deposited on MOR flanks. However in more detail, Mn and Ti enrichments in the ferromanganese ores are more striking than the modern counterpart, suggesting a significant contribution of hydrogenetic component in the Kunimiyama ores. Our results are consistent with the interpretation that the Kunimiyama ores were umber deposits that primarily formed by hydrothermal plume fall-out precipitation in the Panthalassa Ocean during the Early Permian and then accreted onto the proto-Japanese island arc during the Middle Jurassic. The presence of strong negative Ce anomaly in the Kunimiyama ores may indicate that the Early Permian Panthalassa seawater had a more striking negative Ce anomaly due to a more oxidizing oceanic condition than today. 相似文献
5.
Although Mn is one of the major impurities in the economic iron ores from the Bahariya Oasis, information on its modes of occurrence and origin is lacking in previous studies. High-Mn iron ores from El Gedida and Ghorabi–Nasser iron mines were subjected to detailed mineralogical, geochemical, and petrographic investigations using X-ray diffraction (XRD), infrared absorption spectrometry (IR), Raman spectroscopy, X-ray fluorescence (XRF), scanning electron microscopy (SEM), and electron probe microanalyzer (EPMA) to clarify the modes of occurrence of Mn in these deposits and its origin. The results showed that the MnO2 contents range between 0.03 and 13.9 wt.%. Three mineralogical types have been identified for the Mn in the high-Mn iron ores, including: (1) inclusions within the hematite and goethite and/or Mn accumulated on their active surfaces, (2) coarse-grained and crystalline pyrolusite, and (3) fine-grained cement-like Mn oxide and hydroxide minerals (bixbyite, cryptomelane, aurorite, romanechite, manjiroite, and pyrochroite) between the Fe-bearing minerals. The Mn carbonate mineral (rhodochrosite) was detected only in the Ghorabi–Nasser high-Mn iron ores. Since IR patterns of low-Mn and high-Mn samples are almost the same, a combination of XRD analysis using non-filtered Fe-Kα radiations and Raman spectroscopy could be the best way to identify and distinguish between different Mn minerals.Assuming that both Fe and Mn were derived from the same source, the occurrence of high-Mn iron ores at the base of the stratigraphic section of the deposits overlain by the low-Mn iron ores indicated a supergene origin of the studied ores by descending solutions. The predominance of Mn oxide and hydroxide minerals in botryoidal shapes supports this interpretation. The small grain size of Mn-bearing minerals as well as the features of microbial fossils such as spherical, elliptical, and filamentous shapes of the Fe-bearing minerals suggested a microbial origin of studied iron ores.Variations in the distribution and mineralogy types of Mn in the iron ores of the Bahariya Oasis demanded detailed mineralogical and petrographic characterizations of the deposits before the beneficiation of high-Mn iron ores from the Bahariya Oasis as feedstock for the ironmaking industries in Egypt by magnetizing reduction. High Mn contents, especially in the Ghorabi–Nasser iron ore and occurrence of Mn as inclusions and/or accumulated on the surface of the Fe-bearing minerals would suggest a possible utilization of the high-Mn iron ores to produce ferromanganese alloys. 相似文献
6.
《Journal of Asian Earth Sciences》2007,29(2-3):455-465
In Pakistan manganese and ferromanganese ores have been reported from the Hazara area of North West Frontier Province, Waziristan agencies in the Federally Administered Tribal Areas and the Lasbela-Khuzdar regions of Baluchistan. This study is focused on comparison of mineralogy and geochemistry of the continental ferromanganese ores of Hazara and the ophiolitic manganese ores of the Waziristan area of Pakistan. In the Hazara area, ferromanganese ores occur at Kakul, Galdanian and Chura Gali, near Abbottabad, within the Hazira Formation of the Kalachitta-Margala thrust belt of the NW Himalayas of the Indo-Pakistan Plate. The Cambrian Hazira Formation is composed of reddish-brown ferruginous siltstone, with variable amounts of clay, shale, ferromanganese ores, phosphorite and barite. In Waziristan, manganese ores occur at Shuidar, Mohammad Khel and Saidgi, within the Waziristan ophiolite complex, on the western margin of the Indo-Pakistan Plate in NW Pakistan. These banded and massive ores are hosted by metachert and overlie metavolcanics.The ferromanganese ores of the Hazara area contain variable amount of bixbyite, partridgeite, hollandite, pyrolusite and braunite. Bixbyite and partridgeite are the dominant Mn-bearing phases. Hematite dominates in Fe-rich ores. Gangue minerals are iron-rich clay, alumino-phosphate minerals, apatite, barite and glauconite are present in variable amounts, in both Fe-rich and Mn-rich varieties. The texture of the ore phases indicates greenschist facies metamorphism. The Waziristan ores are composed of braunite, with minor pyrolusite and hollandite. Hematite occurs as an additional minor phase in the Fe-rich ores of the Shuidar area. The only silicate phase in these ores is cryptocrystalline quartz.The chemical composition of the ferromanganese ores in Hazara suggests that the Mn–Fe was contributed by both hydrogenous and hydrothermal sources, while the manganese ores of Waziristan originated only from a hydrothermal source. It is suggested that the Fe–Mn ores of the Hazara area originated from a mixed hydrothermal–hydrogenetic source in shallow water in a ontinental shelf environment due to the transgression and regression of the sea, while the Mn ores of Waziristan were formed at sea-floor spreading centers within the Neo-Tethys Ocean, and were later obducted as part of the Waziristan ophiolite complex. 相似文献
7.
Hydrothermal manganese and ferromanganese deposits associated with Neyriz ophiolite colored mélange occurred as small ore deposits in the Abadeh-Tashk area, SE of Fars Province, SW Iran. The deposits are found in three types: a) banded syngenetic ores, b) massive boudin and lens shaped diagenetic ores and c) vein and veinlet epigenetic ores. Microtextural, geochemical and mineralogical data associated with petrographic Raman, FTIR and SEM studies indicated that the primary Fe compounds formed series of microbially mediated biomats and Mn compounds were precipitated as an amorphous oxide on an active oxide surface accompanying silica gels. Field relationships between ore and host rock, high Mn/Fe ratio (17.43 to 40.79), ΣLREE, positive Eu and negative Ce anomalies in syngenetic ore types reveal that the ores were formed by hydrothermal fluid in an oceanic floor environment. Manganese was fractionated from iron due to physicochemical changes as well as microbial activities in the sedimentary environment. Microbial remains as filamentous beads with regular circular shapes, vermiform structures, series of Fe-rich biomats, traces of embedded organic material besides trace metals and REE concentrations in Mn ores emphasize the role of microorganisms in Fe and Mn precipitation. Syngenetic mineralization took place under suboxic neutrophilic conditions, while diagenetic processes resulted in variably reduced Fe- and Mn-oxides via organic matter decomposition, forming rhodochrosite as the end product. Braunite formation occurred most probably as a biogeochemically mediated early diagenetic product. Diagenetic and epigenetic Mn ores were formed when primary Mn deposits underwent subsequent diagenetic and remobilization–redeposition events respectively. 相似文献
8.
Processes governing the formation of rare earth elements (REE) composition are considered for ferromanganese deposits (nodules, separate parts of nodules, and micronodules of different fractions) within the Clarion–Clipperton ore province in the Pacific Ocean. It is shown that ferromanganese oxyhydroxide deposits with different chemical compositions can be produced in sediments under similar sedimentation conditions. In areas with high bioproductivity, the size of micronodules has a positive correlation with the Mn content and Mn/Fe and P/Fe ratios and a negative correlation with Fe, P, REE, and Ce anomaly. The behavior of REE in micronodules from sediments within bioproductive zones is related to increase of the influence of diagenetic processes in sediments as a response to the growth of the size of micronodules. Distinctions in the chemical composition of micronodules and nodules are related to their interrelations with associated sediments. Micronodules grow in sediments using hydrogenous ferromanganese oxyhydroxides. As they grow, micronodules are enriched in the labile fraction of sediments reworked during diagenesis. Sources of the material of ferromanganese nodules are governed by their formation at the water bottom interface. Their upper part is formed by direct settling of iron oxyhydroxides from the bottom water, whereas the lower part is accumulated due to diagenetic processes in sediments. Differences of REE compositions in ferromanganese deposits are caused by the reduction of manganese during diagenesis and its separation from iron. Iron oxyhydroxides form a sorption complex due to the sorption of phosphate-ion from bottom and pore waters. The sorption of phosphate-ion results in an additional sorption of REE. 相似文献
9.
Some geological, petrochemical, and geochemical characteristics of carbonaceous shales as a new unconventional natural source of gold and PGE are considered by the example of the Kimkan and Sutyr’ units of the Bureya massif (southern Far East, Russia). It is shown that shales of the units belong to the terrigenous-carbonaceous and siliceous-carbonaceous formations. They accumulated in deep-water trenches, and the active continental margin was probably their main provenance. The carbonaceous terrigenous-sedimentary units and precious-metalores in them show specific petrochemical characteristics different for complexes with predominantly PGE and gold mineralization. According to these characteristics, carbonaceous complexes with high Fe contents, low total contents of alkalies, and high K/Na ratios are promising for PGE-rich ores. Gold ores are usually localized in black-shale strata with high total contents of alkalies and low K/Na. In this respect, the shales and Fe-ores of the Kimkan unit obviously contain high-PGE mineralization, while the rocks of the Sutyr’ unit can bear gold deposits. We assume that the PGE mineralization is genetically related to the formation and transformation of carbonaceous rocks. At the same time, most of gold in the carbonaceous shales is native and is not related to carbon; it is present in mineral assemblages resulted from superimposed sulfidization and silicification. 相似文献
10.
A. I. Khanchuk I. Yu. Rasskazov T. N. Aleksandrova V. S. Komarova 《Russian Journal of Pacific Geology》2012,6(5):339-348
The results of mineralogical-technological studies of carbonaceous rocks of the Kimkan noble metal occurrence are reported. New typomorphic associations of trace element are revealed using mathematical statistics. 相似文献
11.
Bodies of cryptovolcanic rocks (fluidolites) play a significant role in the structure of the Poperechnoe ferromanganese deposit, Lesser Khingan, Russia. Fe-Mn ores in association with fluidolites are localized in ancient carbonate rocks. PGM, gold, and silver minerals up to tenths of a millimeter in size are established in the rocks and ores of the deposit. Characteristic admixtures in the platinum are iron (9-11%), with less common copper, iridium, and osmium. An intergrowth of isoferroplatinum polycrystal with forsterite is observed. There are also individual grains of Os-Ir-Ru-Rh intermetallides. The gold grains (up to 93% Au) are characterized by dendritic and clumpy morphology, frequently showing faceting elements. The grains are frequently rounded and sometimes have an almost perfect spherical shape. Native silver is distributed among the dolomites, as well as in the dolomitic fragments from the fluidolites. Ubiquitous admixtures in the silver are copper, iron, and more rarely zinc; single grains contain admixtures of molybdenum, nickel, gold, and palladium. PGM and high-fineness gold are related to the fluidolites, which are the only magmatic rocks in the studied range of the deposit. Silver, its minerals, low-fineness gold, and sulfides are confined to the rocks and ores subjected to the regional dolomitization, low-temperature hydrothermal reworking, and silicification. Samples contain up to 11.3 g/t platinum, 2.35 g/t gold, 296.2 g/t silver, which allows us to consider the studied object as economically promising for noble metals. 相似文献
12.
Abstract: The metamorphosed sedimentary type of iron deposits (BIF) is the most important type of iron deposits in the world, and super-large iron ore clusters of this type include the Quadrilatero Ferrifero district and Carajas in Brazil, Hamersley in Australia, Kursk in Russia, Central Province of India and Anshan-Benxi in China. Subordinated types of iron deposits are magmatic, volcanic-hosted and sedimentary ones. This paper briefly introduces the geological characteristics of major super-large iron ore clusters in the world. The proven reserves of iron ores in China are relatively abundant, but they are mainly low-grade ores. Moreover, a considerate part of iron ores are difficult to utilize for their difficult ore dressing, deep burial or other reasons. Iron ore deposits are relatively concentrated in 11 metallogenic provinces (belts), such as the Anshan-Benxi, eastern Hebei, Xichang-Central Yunnan Province and middle-lower reaches of Yangtze River. The main minerogenetic epoches vary widely from the Archean to Quaternary, and are mainly the Late Archean to Middle Proterozoic, Variscan, and Yanshanian periods. The main 7 genetic types of iron deposits in China are metamorphosed sedimentary type (BIF), magmatic type, volcanic-hosted type, skarn type, hydrothermal type, sedimentary type and weathered leaching type. The iron-rich ores occur predominantly in the skarn and marine volcanic-hosted iron deposits, locally in the metamorphosed sedimentary type (BIF) as hydrothermal reformation products. The theory of minerogenetic series of mineral deposits and minerogenic models has applied in investigation and prospecting of iron ore deposits. A combination of deep analyses of aeromagnetic anomalies and geomagnetic anomalies, with gravity anomalies are an effective method to seeking large and deep-buried iron deposits. China has a relatively great ore-searching potential of iron ores, especially for metamorphosed sedimentary, skarn, and marine volcanic-hosted iron deposits. For the lower guarantee degree of iron and steel industry, China should give a trading and open the foreign mining markets. 相似文献
13.
Iron and phosphorite ores are very common in the geological record of Egypt and exploitable for economic purposes. In some cases these deposits belong together to the same geographic and geologic setting. The most common deposits include phosphorites, glauconites, and iron ores. Phosphorites are widely distributed as a belt in the central and southern part of Egypt. Sedimentary iron ores include oolitic ironstone of Aswan area and karstified iron ore of Bahria Oasis. Glauconites occur in the Western Desert associated with phosphorites and iron ores. As these ores are exploitable and phosphorus in iron ores and iron in phosphorites are considered as gangue elements, the iron–phosphorus relationship is examined in these deposits to clarify their modes of occurrences and genetic relationship based on previously published results.Phosphorus occurs mainly as carbonate fluorapatite (francolite). Iron, on the other hand, occurs in different mineralogical forms such as glauconites, hematite, limonite and goethite.In P-rich rocks (phosphorites) no relationship is observed between iron and phosphorus, which in turn indicates that the FeP model is unlikely to interpret the origin of the late Cretaceous phosphorites and the association of phosphorites and glauconites in Egypt. In Fe-rich rocks (iron ores and glauconites) also no relationship between iron and phosphorus is observed. The present work, therefore, does not support the hypothesis that there is a genetic relationship between phosphorus and iron in sedimentary rocks. 相似文献
14.
Yu. N. Smirnova A. A. Sorokin A. B. Kotov V. P. Kovach 《Stratigraphy and Geological Correlation》2016,24(3):219-241
This work presents the results of geological, geochemical, and Sm-Nd isotopic and geochemical studies of Late Riphean–Cambrian terrigenous rocks of the Khingan Group of the Lesser Khingan Terrane of the Central Asian Fold Belt, as well as the results of U-Pb geochronological (LA-ICP-MS) studies of detrital zircons from these deposits. These deposits are the most ancient in the structure of the terrain. It was found that the deposits of Iginchi and underlying Murandavi formations are attributed to the Late Riphean–Vendian age interval, and the Kimkan sequence, to the Late Cambrian–Early Ordovician. The periods of formation of the Murandavi and Iginchi formations, on one hand, and the Kimkan sequence, on the other hand, are separated by the stage of granitoid magmatism at the turn of the Vendian–Cambrian. Because of this, they cannot be attributed to a unified sedimentary sequence. It is the most probable that the sedimentation of the Iginchi and Murandavi formations and the Kimkan sequence occurred under subduction conditions against the backdrop of magmatic activity. 相似文献
15.
凉山州境内的富铁矿按成因可分为火山型、热液型、沉积变质型、沉积型等类型,本文逐一对其分布、地质特征及规模等方面进行了叙述和总结;对主要富铁矿产地和储量作了统计,并介绍了主要矿区开发现状及经济效益。提出了今后矿山开发、资源保扩及寻找富铁矿的建议。 相似文献
16.
It is shown that siderite is unstable during sedimentation, diagenesis, and metamorphism of sedimentary and volcanosedimentary rocks. Regularities in the distribution of siderite in Precambrian jaspilites (iron formations), metasomatic ores of the Bakal type, continental–marine coaliferous formations, and oolitic iron ores are discussed. The genesis of the Precambrian iron formations and Riphean–Lower Paleozoic elisional–hydrothermal deposits is considered. The genetic relation of nodular siderites from coaliferous formations and oolitic iron ores with lowmoor coal-forming peat deposits is noted. 相似文献
17.
18.
Results of the study of carbonaceous metasedimentary rocks in the northern part of the Khanka and eastern part of the Bureya massifs (Primorye and Khabarovsk territories, JAR) and associated platinum mineralization are presented. It is shown that platinum minerals are represented by microparticle dispersion in shales of the greenschist-facies metamorphism (Sutyr and Kimkan sequences, Mitrofanovo Formation) and by Pt and PtO2 nanoparticles associated closely with graphite in shales of the amphibolite facies (Turgenev and Soyuznoe graphite deposits). The studied carbonaceous sequences were likely formed in the hemipelagic setting in a suprasubduction trench during the intense input of terrigenous material into basin. Carbon was derived from the marine biogenic material and superimposed graphitization related to a lower crustal material. Iron ores in the carbonaceous shales are hydrothermal formations. Platinum mineralization was likely related to two sources: (i) sedimentary-chemogenic source that made up the protolith of graphite–sericite–quartz shales of the Sutyr and Kimkan sequences (Mitrofanovo Formation); (ii) graphitizing fluid generated in deep magma chambers. Mineralization produced from these sources is transformed during the hydrothermal activity (coarsening of microparticles) and/or regional metamorphism (disintegration of microparticles and remobilization of Pt into graphite). 相似文献
19.
矽卡岩型铁矿的铁质来源与迁移富集机理探讨 总被引：4，自引：0，他引：4
矽卡岩型铁矿是我国最重要的富铁矿类型,其铁质来源及迁移富集机理是目前最核心、也最具争议的问题之一。本文在矽卡岩矿床复杂性和多成因性研究的基础上,对浅部铁质活化、迁移和富集机理进行整理归纳,建立了流程图;分别探讨了不同类矽卡岩型铁矿铁质的最大可能来源,认为与中酸性侵入体有关的该类铁矿,铁质主要源于浅部侵入岩;与酸性侵入体有关的该类铁矿,矿床附近的原始赋铁层位可能提供了大量铁质。但并非所有与酸性岩有关的此类铁床附近都存在赋铁地层,故本文对铁质深部来源的可能性进行了探讨,结合"岩浆矽卡岩-富碱侵入岩对"的概念,提出了全新的深部铁质活化、运移和富集的可能模式,即深部岩浆同化钙质岩石融离出的富铁矿浆上升并运移到浅部侵入岩与碳酸盐岩的接触带附近,与该系统中的热液相遇并反应,热液吸收矿浆中的铁质生成富铁的复合热液,后复合热液在接触带因物理化学条件的剧变而沉淀成矿。 相似文献
20.
Datangpo-type sedimentary manganese deposits, which are located in northeastern Guizhou province and its adjacent areas, are Mn carbonate-type deposits hosted in black carbonaceous shale that represent a series of medium to large deposits containing a huge tonnage of reserves. PAAS-normalized rare earth element distribution patterns of manganese ores record “hat-shaped” REY (REE + Y) plots characterized by pronounced middle rare earth element enrichment, evident positive Ce anomalies, weak to strong positive Eu anomalies and negligible negative Y anomalies. These REY geochemical characteristics are different from those of country rocks and record the processes and features of sedimentation and diagenesis. Manganese was precipitated as Mn-oxyhydroxide particles in oxidized water columns with the sorption of a certain amount of rare earth elements, subsequently transforming from Mn-oxyhydroxides to rhodochrosite and redistributing REY in reducing alkaline pore-water during early diagenesis. A number of similarities can be observed through a comparison of Datangpo-type manganese ores and modern marine ferromanganese oxyhydroxide precipitates based on their rare earth elements. The precipitation of Datangpo-type manganese ores is similar to that of hydrogenetic crusts and nodules based on their positive Ce anomalies and relatively higher total REY concentrations. However, several differences also exist. Compared to hydrogenetic crusts and nodules, Datangpo-type manganese ores record smaller positive Ce anomalies, lower total REY concentrations, unobvious fractionation between Y and Ho, and weak to strong positive Eu anomalies. These were caused by quicker sedimentary rates in the oxic water columns of the shallower basin, after which pore water became strongly reducing and alkaline due to the degradation of organic matter in the early diagenetic stage. In addition, compared to typical deposits in the world, Datangpo-type manganese ores are similar to hydrogenetic deposits and different than hydrothermal deposits. All of these characteristics of manganese ores indicate that Datangpo-type manganese ores, the principal metallogenic factors of which include oxidation conditions during deposition and reducing conditions during early diagenetic stages, represent hydrogenetic deposits. 相似文献