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1.
In the southern Korean Peninsula twelve quartzite strata occur in the Gyeonggi massif and Okcheon belt. Their geologic ages range from Precambrian to Upper Paleozoic. All quartzites in the Gyeonggi massif are of Precambrian in age and are characterized by high-grade metaquartzites; they are Seosan, Anyang, Yongmunsan and Uiam quartzites from west to east. Quartzite types occurring in the Okcheon belt are diverse from orthoquartzite to medium-grade metaquartzite. Orthoquartzites are all Paleozoic in age and are distributed mainly in the eastern Okcheon belt (Taebaeksan Basin) (Jangsan, Dongjeom and Jeongseon quartzites) with one in the central Okcheon belt (Mungyeong Quartzite). Low-grade metaquartzite is Hwasan quartzite in the western part and medium-grade metaquartzites are Daehyangsan and Geumsusan quatzites in the central part, and Yongamsan quartzite in the southwestern part of the Okcheon belt. Distribution of quartzite types in the southern Korean Peninsula is not related to the geologic age of quartzites. As a case study, quartzite characteristics were applied to a provenance study of quartzite clasts in the northwestern part of the Cretaceous Gyeongsang Basin. Quartzite clasts in the study area are interpreted to have been mostly derived from source quartzites in the Okcheon belt, which is consistent with the results of previous studies. 相似文献
2.
《International Geology Review》2012,54(10):1565-1572
A critical coordination of the often contradictory ideas on the relation of secondary quartzites to volcanism, granitoid intrusions, and deposition of endogenic ores, represents them essentially as products of postvolcanic hydrothermalism, as metasomatites, and as predecessors of the ores. Physicomechanical and chemical properties of secondary quartzites, and also their morphology and structural positions are particularly conducive to their functioning as barriers or screens in the deposition of ores. The very same properties, genetically inherent, usually disqualify secondary quartzites as potential host rocks of the imposed ores. 相似文献
3.
《International Geology Review》2012,54(10):1365-1375
A peculiar horizon of tourmaline-bearing quartzites has been identified in the study of basic intrusives of the South Urals. This horizon is quite consistent along the contacts of gabbro massifs, with the quartzites strongly metasomatized and altered in both structure and mineral composition. The tourmaline appears to be the result of an alkali metasomatism related to granitic intrusions. The principal sequence is albite, tourmaline and quartz. The quartzites appear to be of sedimentary origin, as they form a consistent horizon traceable for tens of kilometers and are intercalated with similarly consistent horizons of hornfels and schists. — F. E. Ingerson. 相似文献
4.
Lenses of radioactive Quartz Pebble Conglomerates (QPC) and associated quartzites are exposed along western margin of Archean Bonai Granite in Singhbhum-Orissa Craton, eastern India intermittently spreading over a strike length of 8–10 km. QPCs are radioactive while quartzites are mostly non-radioactive in nature. The purpose of the research is to investigate and characterize the radioactive QPC and quartzites geochemically to decipher their paleo-weathering conditions, provenance characteristics and possible tectonic setting of deposition. Geochemical data suggest moderate to high chemical weathering conditions in the provenance areas of QPC and quartzites. Major, trace and REE data indicate predominantly felsic to partly mafic-ultramafic sources for the deposition of radioactive Quartz Pebble Conglomerates from the surrounding Archean terrain.Elevated values of Th, U, Pb, La, Ce, Y and low Sc with high critical trace elemental ratios of Th/Sc, La/Sc, Th/Cr and Zr/Sc in radioactive QPC indicate their derivation from felsic igneous source. Low concentration of Th and Sc in quartzites compared to QPC and their variable Th/Sc ratios indicate both felsic and mafic sources for quartzites, albeit their preferential felsic affiliation. Higher Cr/Th ratios in quartzites (18.4), moderate Cr/Th in QPC (5.42), low to moderate Y/Ni in QPC (0.36–12.4) and quartzite (0.29–1.88), along with Au ranging from 30 to 1527 ppb, Pt up to 188 ppb and 682 ppb in QPC and quartzites respectively point towards some contribution from mafic-ultramafic source as well. REE patterns and in particular negative Eu anomalies for both QPC and quartzites further support their derivation from felsic rocks and could possibly linked to some of the phases of Archean Singhbhum Granite and Bonai Granite. Granitic to pegmatitic source for QPC is also revealed by the presence of rounded to sub-rounded monazite, zircon and thorian-uraninite grains in their matrix. Study indicates that QPC and quartzites were deposited in a passive margin tectonic setting developed during Archean between a span of 3.3 and 3.16 Ga along the western margin of Bonai Granite when the reducing condition was prevalent as indicated by their low Th/U ratios (<4.0) and presence of detrital grains of uraninite and pyrite in QPC. Radioactive QPC from western margin of Archean Singhbhum-Orissa Craton bears broad resemblance with QPC from Witwatersrand basin of South Africa and Elliot Lake, Canada and thus appears to be ideal sites for exploring QPC hosted U (+Au-PGE) mineralization in the analogous areas. 相似文献
5.
ABSTRACT The Pan-African orogeny left a strong imprint on the basement rocks of Madagascar, which were metamorphosed up to granulite facies conditions. The supracrustal Itremo Group of central Madagascar, comprising quartzites, schists and carbonates of lower metamorphic grade, has to date been described as a folded sedimentary sequence. Despite their fine-grained 'sugary' appearance, most quartzites are plastically deformed tectonites. Quartzite microstructures are mainly of the elongate mosaic type, indicating significant grain boundary migration, and are compatible with dynamic recrystallization under lower amphibolite facies conditions. Consistent asymmetric quartz c -axis fabrics indicate a dominant top-to-the-east shear sense. Hence, the Itremo quartzites bear evidence for a major eastward-directed tectonic event of Pan-African age, possibly resulting from an early Pan-African thrust motion. Younger deformational events, responsible for localized mylonites with top-to-the-WSW sense of motion and N–S-trending folds and shear zones, were superimposed on this first fabric. 相似文献
6.
Miros&#x;aw Jastrz&#x;bski Bartosz Budzy&#x; Wojciech Stawikowski 《Geological Journal》2016,51(3):455-479
This integrated study on the pressure–temperature–deformation‐time record of the Goszów light quartzites from the Młynowiec–Stronie Group (Sudety Mts., SW Poland) provides new data that improve our understanding of the structure and geodynamic development of the Orlica–Śnieżnik Dome (OSD) as a Gondwana‐derived unit involved in the formation of the Variscan orogen. The structural and metamorphic record of the Goszów light quartzites, when compared to the under‐ and overlying rock formations, indicates that the whole Młynowiec–Stronie Group in the eastern part of the Saxothuringian terrane functioned as a single, integral lithotectonic unit with no visible structural or metamorphic discontinuities. The sequence of structures and thermodynamic modelling indicate that the light quartzites underwent the same polyphase tectonometamorphic evolution as the adjacent rocks belonging to the Młynowiec–Stronie Group. The development of tight, N–S‐trending folds and axial penetrative metamorphic foliation was related to metamorphic progression from 500 °C to 640 °C at 6–7 kbar. Subsequently, under the retrogressive conditions below 540 °C, the foliation was reactivated as a result of subsequent N–S‐directed ductile shearing and extension. Therefore, the study of the light quartzites exemplifies the penetrative structures in the OSD, and the metamorphic foliation and N–S‐trending lineation are composite structures. The monazite metamorphic ages of ca. 364 Ma and 335 Ma may be related to the approximately E–W‐ and N–S‐oriented tectonic movements, respectively, which occurred during the amalgamation of the Saxothuringian terrane with Brunovistulia. In contrast, the previously unknown early Palaeozoic monazite age of ca. 494 Ma is interpreted as the protolith age of the light quartzites. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
7.
C.S.Sindhuja Arijit Pahari C.Manikyamba M.Santosh Li Tang Jyotisankar Ray K.S.V.Subramanyam Madhuparna Paul I.Gonzalez-Alvarez P.C.Sruthi 《地学前缘(英文版)》2022,13(1):101257
Cratonic stabilization was a critical crustal process during the Hadean to Archean for the formation of cratons.The understanding of how and where this process took place is significant to evaluate the architecture of continents.The Singhbhum Craton of eastern India has well preserved Precambrian volcanosedimentary sequences.The Simlipal volcano-sedimentary complex of Singhbhum Craton consists of circular bands of mafic volcanic rocks interlayered with quartzites/shales/phyllites.In the present study,we report petrographic and geochemical characteristics of quartzites from Simlipal Complex coupled with U–Pb ages of detrital zircons and zircon geochemistry to understand the provenance and depositional conditions and its connection with the crustal stabilization in the Singhbhum Craton.The quartzites are texturally mature with sub-angular to sub-rounded quartz grains followed by feldspars embedded in a silty matrix.Based on modal compositions and major element ratios,these quartzites are categorized as quartz arenite and sub-lithic arenites.Trace element abundances normalized to Archean Upper Continental Crust(AUCC)display positive anomalies at U,Zr,Hf and negative anomalies at Nb.REE patterns are characterized by negative Eu anomalies(Eu/Eu*=0.47–0.97)and flat HREE suggesting felsic provenance.These quartzites show depletion of LILE,enrichment of HFSE and transition metals relative to AUCC.High weathering indices such as CIA,PIA,and ICV are suggestive of moderate to intense chemical weathering.Low trace element ratios such as Th/Cr,Th/Sc,La/Sc,La/Co and Th/Co indicate a predominantly felsic source for these rocks.The overall geochemical signatures indicate passive margin deposition for these quartzites.Detrital zircons from the Simlipal quartzites yield U–Pb ages 3156±31 Ma suggesting Mesoarchean crustal heritage.The trace element geochemistry of detrital zircons suggests that the zircons are magmatic in origin and possibly derived from the 3.1 Ga anorogenic granite/granitoid provenance of Singhbhum Craton.These observations collectively indicate the Mayurbhanj Granite and Singhbhum Granite(SBG-III)provenance for these quartzites,thereby tracking the stabilization of the eastern Indian Shield/Singhbhum Craton back to Mesoarchean. 相似文献
8.
硬玉石英岩是一种稀少且与流体作用相关的变质岩,同时出露于高压或超高压洋壳和陆壳俯冲带中.通过对中国东部大别造山带中出露达50 km2的含柯石英的超高压硬玉石英岩进行研究,综合全岩主微量元素、矿物Mg-O同位素和锆石学研究.结果表明,硬玉石英岩的原岩为古元古代TTG岩石,经历过弱化学风化和强物理风化作用,然后在三叠纪时期受到围岩富黑云母片麻岩分解脱水而产生的大量重Mg同位素流体交代,从而形成硬玉石英岩.考虑到这种受流体交代成因的硬玉石英岩在大别山广泛出露,表明其在三叠纪大陆深俯冲过程中存在着大规模的变质流体活动,这项研究首次报道了大陆俯冲带有大规模的流体活动存在,同时也挑战了传统观点认为的大陆俯冲带缺乏岛弧岩浆作用主要原因是缺乏足够量的流体活动. 相似文献
9.
SHRIMP U–Pb zircon analysis indicates that detrital zircons from extensive quartzite units in the Southern Cross Granite‐Greenstone Terrane of the central Yilgarn Craton have ages ranging from ca 4350 Ma to ca 3130 Ma. Regional mapping studies indicate that the quartzites lie at the stratigraphic base of the exposed succession. The detrital zircon age profiles of the Southern Cross Granite‐Greenstone Terrane quartzites are remarkably similar to those of quartzites in the Narryer and South West Terranes, in the northwest and southwest of the Yilgarn Craton respectively, and are significantly older than any igneous rocks that have been dated anywhere in the Yilgarn Craton other than the Narryer Terrane. Similar detrital‐zircon‐bearing quartzites have not been identified in the Murchison Granite‐Greenstone Terrane. These age profiles suggest that the quartzites have a common depositional history. Granites in the central Yilgarn Craton are mainly younger than ca 2750 Ma and contain rare xenocrystic zircons older than 3100 Ma. If the central and western Yilgarn quartzites were all deposited at approximately the same time, the lack of preserved continental crust in the Southern Cross and Murchison Granite‐Greenstone Terranes, and the South West Terrane, that is older than 3100 Ma, suggests that pre‐3100 Ma Narryer‐like continental crust may have been rifted or extensively reworked during deposition of greenstone successions between ca 3000 and ca 2700 Ma. If not, then a ca 4350 Ma detrital zircon in the Southern Cross Granite‐Greenstone Terrane indicates more widespread, very old, continental crust than has previously been identified. 相似文献
10.
S. B. Lobach-Zhuchenko V. V. Balagansky Sh. K. Baltybaev G. V. Artemenko E. S. Bogomolov A. V. Yurchenko L. M. Stepanyuk V. V. Sukach 《Lithology and Mineral Resources》2014,49(5):381-397
Paleoarchean granulite-facies metasedimentary rocks (quartzites, garnet quartzites, garnet-pyroxene gneisses, pyroxene-magnetite and magnetite quartzites) attributed to the Dniester-Bug Group of the Ukrainian Shield were studied. On the basis of geochemical data, including REE, the primary composition of these rocks was reconstructed as association of Fe-rich sandstones and sublitharenites, Fe-shales, and BIFs. This sedimentary association is similar to the rocks of other ancient greenstone belts and ascribed to the Algama-type iron formation. The sum of Al2O3, CaO, Na2O, and TiO2, high Zr contents (>100 ppm in quartzites), and the presence of detrital zircon grains of different ages are consistent with the terrigenous nature of sedimentary rocks. The Sm/Nd, Ti/Zr, Sc/Zr, and Ni/Zr ratios indicate the predominance of granitoid rocks in the source areas. The elevated Cr contents suggest that, in addition to granitoids, the source area contained ultramafic rocks. Geochemical characteristics, such as Fe/Mn ratio, low REE contents, and variations of REE versus the sum of Ni, Co, and Cu testify that sedimentation occurred under shallow-water conditions on the continent or its slope, similarly as the formation of ancient (3.5–3.2 Ga) basalt-komatiitic series intercalated with sedimentary rocks in the Pilbara Craton. The age of supracrustal rocks of the Dniester-Bug Group was constrained within the time interval of 3.4–3.2 Ga on the basis of U-Pb zircon dating and determination of Nd isotope composition. The DM model age of quartzites varies from 3.37 to 3.5 Ga. Sedimentary rocks together with volcanic rocks represent the oldest supracrustal association of the East European Platform. 相似文献
11.
Savko A. D. Nikulin I. I. Ovchinnikova M. Yu. Boeva N. M. 《Lithology and Mineral Resources》2022,57(4):290-298
Lithology and Mineral Resources - High-grade iron ores and bauxites of the Kursk magnetic anomaly (KMA) were formed in weathering crusts on the Early Precambrian ferruginous quartzites and shales,... 相似文献
12.
Epidiorites forming the basement and occurring also as bands in ferruginous quartzites in Kemmangundi in the Bababudan Hills of Mysore State are described in regard to their structure, mineralogy, petrography, and the petrochemistry of the epidiorites and their role in the formation of the two types of iron ores in the area. The ferruginous quartzites, itabiritic iron ores, and epidiorites strike NW-SE and were simultaneously structurally deformed. They may be considered as eugeosynclinal formations. The data collected do not suggest any genetic relation between the itabiritic ores and the epidiorites. The lateritic iron ores on the other hand, were formed by the alteration of the ferruginous quartzites (itabiritic ores).
Zusammenfassung Itabiritische Quarzite und Epidiorite aus Kemmangundi in den Bababudan-Hügeln des Staates Mysore wurden hinsichtlich ihrer Struktur, ihres Mineralbestandes und ihrer chemischen Zusammensetzung untersucht. Insbesondere wird der Zusammenhang mit den beiden Typen von Eisenlagerstätten in der Gegend beleuchtet: Die itabiritischen Quarzite haben sich nicht aus den Epidioriten gebildet; dagegen sind die lateritischen Eisenerze als Verwitterungsprodukte der Eisenquarzite zu betrachten.相似文献
13.
P. G. Spry 《Mineralium Deposita》1987,22(4):262-268
Zincian spinel or gahnite [(Zn,Fe,Mg)Al2O4] occurs in metamorphosed sulphide-rich rocks, garnet quartzites, quartz-magnetite rocks, aluminous metasediments, barite-magnetite rocks, quartz veins, and pegmatites associated with the Aggeneys base metal deposits, Namaqualand, South Africa. Zincian spinel in, sulphide-bearing rocks, is considered to have formed predominantly by desulphurization reactions involving a member of the system Fe-S-O and sphalerite with sillimanite or garnet. Gahnite in sulphide-free garnet quartzites, quartz-magnetite rocks and barite-magnetite rocks probably formed from Zn and Al that were hydrothermally derived whereas gahnite in aluminous metasediments was derived from the metamorphism of metalliferous shales, in which Zn may originally have been linked to organic material. Gahnite is Zn-rich in sulphide-bearing rock, but is Fe-rich in sulphide-free garnet quartzites and quartz-magnetite rocks. Although Zn-rich spinels represent guides to ore in the Aggeneys area and elsewhere in the Namaqualand Metamorphic Complex, Fe-rich spinels should not be discounted because Zn-rich and Fe-rich spinels occur within metres of sulphides at Aggeneys. 相似文献
14.
Geotectonics - In the Dzhetym Range, there are well-known Precambrian massifs of marbled limestones and quartzites, which have no analogues throughout the Middle Tien Shan. The authors establish... 相似文献
15.
《Chemie der Erde / Geochemistry》2022,82(3):125887
Tourmaline is the principal repository of boron in crustal rocks and therefore useful for tracing B-cycling during prograde dehydration and retrogression of supracrustal rocks. Here, we use the major-trace element, and B isotope composition of tourmaline from schists, quartzites, and tourmaline-quartz veins of the Gangpur Schist Belt in eastern India to constrain the source of boron and the physicochemical evolution of B-rich fluids during prograde dehydration metamorphism. Tourmaline growth and re-equilibration in rocks of the Gangpur Schist Belt was a multi-stage process involving several fluid sources. The δ11B varies between ?6‰ and ?18‰, indicating a dominantly continental source for boron. Tourmaline in schists, quartzites, and tourmaline-quartz veins grew over a wide range of P-T conditions and record multiple episodes of metamorphic dehydration between ca. 1.6 Ga and ca. 0.95Ga. The tourmaline in tourmaline-quartz veins and quartzites has lighter B-isotope composition, typical of continental detritus, while those in the schists and quartzites record pelite-dehydration signature with values decreasing gradually from ca. ?12‰ in the cores to ca. ?17‰ in the rims. Heavier isotopic compositions (δ11B of ca. ?6‰) measured in some grains in the pelites and quartzites indicate boron contribution from meta?carbonate sources. The mixing of a heavier B-rich metacarbonate-derived fluid with pelite-derived metamorphic fluids could explain the lower B-isotope values in such tourmaline. The study also attempts to constrain the controls on the intake of trace elements in tourmaline. The results suggest that the partitioning of Mn, Y, V, Co and Ti in tourmaline is affected by the growth of porphyroblast phases such as garnet, staurolite, and biotite, while Li, Sr, Zn and Sn reflect the signature of the metamorphic fluid. 相似文献
16.
George Luiz Luvizotto Thomas Zack Silke Triebold Hilmar von Eynatten 《Mineralogy and Petrology》2009,97(3-4):233-249
Metamorphic textures in medium-grade (~500–550°C) metasedimentary rocks from the Erzgebirge give evidence of prograde rutile crystallization from ilmenite. Newly-crystallized grains occur as rutile-rich polycrystalline aggregates that pseudomorph the shape of the ilmenites. In-situ trace element data (EMP and SIMS) show that rutiles from the higher-grade samples record large scatter in Nb content and have Nb/Ti ratios higher than coexisting ilmenite. This behavior can be predicted using prograde rutile crystallization from ilmenite and indicates that rutiles are reequilibrating their chemistry with remaining ilmenites. On the contrary, rutiles from the lowest grade samples (~480°C) have Nb/Ti ratios that are similar to the ones in ilmenite. Hence, rutiles from these samples did not equilibrate their chemistry with remaining ilmenites. Our data suggest that temperature may be one of the main factors determining whether or not the elements are able to diffuse between the phases and, therefore, reequilibrate. Newly-crystallized rutiles yield temperatures (from ~500 to 630°C, Zr-in-rutile thermometry) that are in agreement with the metamorphic conditions previously determined for the studied rocks. In quartzites from the medium-grade domain (~530°C), inherited detrital rutile grains are detected. They are identified by their distinct chemical composition (high Zr and Nb contents) and textures (single grains surrounded by fine grained ilmenites). Preliminary calculation, based on grain size distribution of rutile in medium-grade metapelites and quartzites that occur in the studied area, show that rutiles derived from quartzites can be anticipated to dominate the detrital rutile population, even if quartzites are a minor component of the exposure. 相似文献
17.
A Paleoproterozoic lateritic paleosol overlain by ultra-mature/mature quartzite is reported for the first time from three localities in the Svecofennian province in southern Finland. These are important indicators for warm paleoclimate and continental paleoenvironment. Ultra-mature quartzites above the lateritic paleosols are overlain by matrix-supported conglomerates followed by mature quartzites. These latter rocks are related to incipient rifting followed by main rift stage starting with increasingly more immature meta-arkose. 相似文献
18.
Three groups of Sn-W veins occur in the contact aureole of composite granitic plutons South of Bragança (Trás-os-Montes, Portugal). Thin layers of calcic quartzites with or without scheelite are interbedded in the Ordovician and Silurian metamorphic country-rocks. Could they represent synsedimentary preconcentrations and a likely source for the W-deposits? The geologic features and the trace-elements distribution (W, Sn, Be, B, Li, F, Rb) in the metasedimentary and granitic rocks support the following conclusions: 1) the scheelite-bearing calcic quartzites are tactites, that occur only in the contact aureole of the granites; 2) the dynamo-metamorphic country-rocks are weakly enriched in W and impoverished in Sn compared to the "clarke" values; 3) the trace-elements concentration is higher in the contact aureole (X 2) than outwards; 4) the quartzites are scheelite-bearing only in the vicinity of the wolframite veins. Thus, scheelite appears related to mineralizing hydrothermal processes. Through their chemical composition and their mechanical properties, the calcic quartzites appear as traps for a tungsten mainly foreign to the metamorphic rocks close to the granites. Thus, the source of W lies deeper in lower crust levels or in the upper-mantle. 相似文献
19.
阿西金矿地处川甘陕“金三角”成矿集中区,中三叠统为本区内最重要的金矿源层和赋矿层。阿西金矿田的形成经历了一个从沉积－成岩－富集成矿的漫长复杂的由量的积累到质的飞跃过程,是多阶段、多层次、多因素作用有机结合的产物。赋矿岩系特征表明,阿西金矿田的主要成矿环境为半深海斜坡环境。区内岩石类型极为复杂,三大岩类均有产出。主要有细砂岩、杂砂岩、沉凝灰岩、碳酸盐岩、硅质岩;变粒岩、石英岩、角岩、大理岩、夕卡岩、角砾岩;岩浆岩类主要为英安斑岩（玢岩）、闪长岩等。其中最重要的赋矿岩石为石英岩,其主要特征为具块状、不规则条带状构造,呈褐黄色／浅灰色变余层状构造。由石英（75％－80％）、高龄石（10％－15％）、绢云母（2％－3％）、钛铁质（3％－4％）、玉髓（2％－3％）及少量碳质组成。其岩石化学成分与典型硅质岩相比,SiO2偏低,Al2O3总体偏高,出现较强的高岭土化。通过研究认为,该区主要赋矿岩石石英岩的原岩应属正常碎屑沉积岩。 相似文献
20.
H. W. Fairbairn 《Mineralogy and Petrology》1954,4(1-4):75-80
Petrofabric investigation of five crossbedded quartzites shows an essentially isotropic fabric in three cases, and preferred orientation together with parallel texture in the remaining two. Crossbedding is undistorted in all five. Recrystallization by solution and re-deposition could satisfactorily explain the three isotropic fabrics. Low-magnitude shear of short duration, coupled with extremely sensitive response of quartz to deformation, is the preferred explanation for the quartzites showing preferred orientation.At a higher metamorphic level in a sheared granite, stress-sensitive quartz and stress-insensitive feldspar are contrasted and, in view of their analogous crystal structures, the apparent anomaly in deformation behavior is noted.With 2 figures. 相似文献