Plot Of TiO2 Research Articles

Geochemical characteristics of the Rajmahal coals in Dhulia North Block, Eastern India: implication to their utilization and environment.

The borehole coal samples of Dhulia North Block from the Rajmahal Basin, Eastern India, were systematically analyzed based on the chemical composition and concentration of major and trace elements (including rare earth elements, REEs) to assess the distribution of REEs and their environmental implications with utilization potential. TheDhulia North Block coals are characterized by the predominant majoroxides of SiO2, Al2O3, and Fe2O3, accounting for 94% of the total ash composition, indicating the presence of quartz, clay-rich minerals, and pyrite. Compared with the average world coal ash, the total REE content in the analyzed samples ranged from 341.0 to 810.4ppm, which is substantially higher. Hot humid climate conditions with intermediate igneous source rocks of the basin were demonstrated by the major oxide ratios (Al2O3/TiO2 < 20) and plots of TiO2 with Al2O3 and Zr. The redox-sensitive elements such as V, Ni, Cr, and Co found in the Dhulia North Block coal indicate that an oxic sedimentary environment existed in the basin when coal was formed. The low sulfur content (1% in most samples) indicates freshwater conditions in the basin at the time of organic matter deposition. The outlook coefficient (Coutl) varies between0.7 and 1.6, indicating that the Dhulia North Block coals are a prospective source of REEs. The Dhulia North Block coals are characterized by low H/C and O/C atomic ratios ranging from 0.56 to 0.90 and 0.10 to 0.22, respectively, and contain type-III kerogens, indicating gas-prone source rock. Further, the basic-to-acid oxide ratio suggested that Dhulia North Block coals were suitable for utilization during combustion processes.

Geochemistry of the mudrocks and sandstones from the Bredasdorp Basin, offshore South Africa: Implications for tectonic provenance and paleoweathering

Abstract An inorganic geochemical investigation of mudrocks and sandstone from the southern Bredasdorp Basin, off the south coast of South Africa was carried out to unravel the provenance, paleoweathering, and tectonic setting of the basin. Seventy-seven representative samples from exploration wells E-AH1, E-AJ1, E-BA1, E-BB1, and E-D3 underwent geochemical analysis involving major and trace elements. The major oxide compositions show that the sandstones could be classified as sub-arkose and sub-lithic arenite. The provenance discrimination diagrams based on major oxide geochemistry revealed that the sandstones are mainly of quartzose sedimentary provenance, while the mudrocks are of quartzose sedimentary and intermediate igneous provenances. The discrimination diagrams indicate that the Bredasdorp sediments were mostly derived from a cratonic interior or recycled orogen. The bivariate plots of TiO2 versus Ni, TiO2 against Zr, and La/Th versus Hf as well as the ternary diagrams of V–Ni–Th∗10 suggest that the mudrocks and sandstones were derived from felsic igneous rocks. The tectonic setting discrimination diagrams support passive-active continental margin setting of the provenance. Also, the closely similar compositions of the analysed samples and recent sedimentary rocks of the East African Rift System perhaps suggest a rifted basin tectonic setting for the Bredasdorp Basin. Chemical index of alteration (CIA) indices observed in the sandstones suggest that their source area underwent low to moderate degree of chemical weathering. However, the mudrocks have high CIA indices suggesting that the source area underwent more intense chemical weathering, possibly due to climatic and/or tectonic variations.

Mineralogy and geochemistry of the sediments in rivers along the east coast of India: Inferences on weathering and provenance

The clay fraction of the sediments in 15 rivers along the east coast of India showed The clay fraction of sediments in the lower reaches of 15 rivers along the east coast of India showed high kaolinite followed by illite and smectite for the rivers dominantly draining the Archaean–Precambrian Terrain (APT), high smectite followed by illite and kaolinite for those draining the Deccan Trap Volcanic Terrain (DVT) and, high illite followed by kaolinite, smectite or chlorite for those draining through Mixed-Lithology Terrain (MLT). The CIA (Chemical Index of Alteration) and PIA (Plagioclase Index of Alteration) values, depletion of Ca, K, Na and Sr and enrichment of Al, Fe and Ti, high Rb/Sr and Th/U ratios of sediments relative to the Upper Continental Crust indicate moderate to intense chemical weathering on source rocks. The average composition of clays exhibits slight enrichment of Fe, Mg, Sc, V, Co, Cr and Ni and depletion of Nb, Zr, Hf, Y and Ta relative to the Post-Archaean average Australian Shale. The Cu, Zn and Pb contents were in the range ‘significantly polluted to moderately polluted’ in APT- and DVT-sediments. The plots of TiO2 vs. Fe2O3+MgO, Th/Sc vs. Sc and La–Th–Sc showed sediment composition intermediate between granite and basalt, while the plots of TiO2 vs. Zr, Th vs. Sc and V–Ni–Th indicate intermediate provenance between mafic and felsic sources. The mineralogy of the sediments indicates mixed sources, but their chemical composition is affected by weathering and the provenance is intermediate between mafic and felsic sources.

Geochemical and Petrographical Characteristics of the Madzaringwe Formation Coal, Mudrocks and Sandstones in the Vele Colliery, Limpopo Province, South Africa: Implications for Tectonic Setting, Provenance and Paleoweathering

The sedimentary rocks of the Madzaringwe Formation in the Tuli Basin have been investigated using geochemical and petrographic methods to reveal their source area composition, tectonic setting, provenance and paleoweathering conditions. The petrographic studies show that the rocks consist mostly of clay minerals and quartz. The major elements geochemistry indicates that the rocks of the Madzaringwe Formation have the same source area. Based on the discriminant function plots, it can be inferred that the rocks are of quartzose sedimentary provenance, suggesting that they were derived from a cratonic interior or recycled orogen. The binary plots of TiO2 versus Zr and La/Sr against Th/Co shows that the rocks were derived from silicic or felsic igneous rocks. The tectonic setting discrimination diagrams of SiO2 against Log (K2O/Na2O), Th–Sc–Zr/10, and TiO2 versus (Fe2O3 + MgO) support passive-active continental margin settings of the provenance. The A–CN–K (Al2O3–CaO + Na2O–K2O) ternary diagram and binary plot of the index of compositional variability (ICV) against chemical index of alteration (CIA) shows that the rocks have been subjected to moderate to intensive weathering. Geochemical and petrographic characteristics of the rocks point to uplifted basement source areas predominantly composed of sedimentary rocks and/or granite-gneiss rocks. These source areas might have been from adjacent areas near the Tuli coalfield which include the Limpopo Belt (igneous and sedimentary rocks), and basement uplifted rocks of the Beit-Bridge Complex, consisting of the granite, granite-gneisses and schists.

Petrography and Geochemistry of Rocks of Northern Part of Wonaka Schist Belt, Northwestern Nigeria

Systematic mapping and sampling of rocks of northern part of Wonaka schist belt on a scale of 1:50,000 shows that the belt is composed of gneiss, granite gneiss, muscovite-biotite schist, banded iron formation, amphibolite, granite, granodiorite and diorite as major rock types, other rocks are aplite, and pegmatite. Petrographic and geochemical data shows that the there are two types of gneisses in the area: the orthogneiss and the paragneiss. Plots of TiO2 vs SiO2 shows that the granite gneiss is paragneiss while the gneiss is an orthogneiss. The granites and the granodiorite are I – Type and the amphibolite is volcaniclastic. The banded iron formation (BIF) is shown to be hematite facies type from a plot of MnO vs FeO(T). It can therefore be said that the orthogneiss represents the original basement rock possibly dating back to the early phase of the Eburnean orogeny. At later stages of the Eburnean, sedimentary deposition and subsequent metamorphism of the sediments might have led to the formation of the paragneiss and the metasediments with the associated BIF as indicated by the REE distribution pattern. The NNE – SSW and the N – S structural trends on the rocks might have been developed by the over printing effects of the Pan- African orogenyKeywords: orthogneiss, schist belt, paragneiss, banded iron formation, metasediments

Geochemistry of Ekenkpon and Nkporo shales, Calabar flank, SE Nigeria: implications for provenance, transportation history and depositional environment

The Cretaceous Nkporo and Ekenkpon Shales within the Calabar Flank were investigated using Inductively Coupled Plasma-Mass Spectroscopy (ICP-MS) and Atomic Emission Spectroscopy (ICP-AES) to deduce the provenance, transportation history and depositional environment. The results show the dominance of SiO2 (45.27 – 46.45%; 44.50 – 54.83%), Al2O3 (22.27 – 23.57%; 19.20 – 20.20%) and Fe2O3 (8.30 – 9.04%; 5.64 – 7.30%) constituting the bulk major oxides of Nkporo and Ekenkpon Shales respectively. The Index of Chemical Variation (ICV) ranges from 0.42 – 0.56 and 0.57– 0.68 for Nkporo and Ekenkpon Shales respectively, suggesting moderate and high degree of weathering. The enrichment of Sr (124 – 350ppm; Nkporo Shale and 176 – 856ppm; Ekenkpon Shale) compared to Post Australian Archean Shale (PAAS; 14.6ppm) could be attributed to feldspars in the source area, and is easily incorporated in the clay minerals of the shales. Also the values of Th and U which are 15.00 – 17.20ppm; 14.6- 23.2ppm and 3.5-4.2ppm; 1.9-6.2ppm respectively in Nkporo and Ekenkpon sediments show enrichment compared to PAAS of 14.6ppm and 3.1ppm for respective values of Th and U. The Eu anomaly of 0.04 to 0.07 suggests felsic source rocks for both formations while plots of TiO2 vs. Al2O3 indicate an intermediate to dominantly felsic granodiorite source for both shales, with little input from felsic volcanic provenance plus traces of quartzose sedimentary rocks. The mobility of Na, Ca, and K due to progressive weathering of the shales is evident in the bivariate plots of Na2O wt% vs. PIA, CaOwt% vs. PIA and K2O vs. PIA. Values of Th/U ratios range from 3.37 – 4.91(Nkporo) and 3.10 – 7.68 (Ekenkpon), indicating moderate to high weathering and reworking of sediments. It is envisaged that the area is associated with passive to active continental margin tectonics, where sediments were mainly sourced from felsic rocks of the adjoining terrain and deposited in oxic, continental to transitional marine environment based on Al2O3– K2O +CaO+MgO-Fe2O3+MgO; AKF plot.KEYWORDS: Cretaceous, Calabar Flank, provenance, transportation history, depositional environment.

Mid-ocean ridge (MOR) and suprasubduction zone (SSZ) geological events in the Yarlung Zangbo suture zone: Evidence from the mineral record of mantle peridotites

The Purang ophiolite in the westernmost Yarlung-Zangbo suture zone of southern Tibet shows a two-stage evolution, on the basis of its mineralogy and geochemistry, having formed originally at a mid-ocean spreading ridge and later been modified in a suprasubduction zone (SSZ) environment. Olivine from the Purang peridotites is highly magnesian (Fo90–92) with NiO contents of 0.32–0.48wt%, consistent with formation in a fore-arc environment. Magnesiochromite in the mantle peridotites has a large range in Mg# [100Mg/(Mg+Fe)] (43.6–67.7) and Cr# [100Cr/(Cr+Al)] (22.3–67.8), reflecting different degrees of partial melting and melt–rock reaction. The Cr#s increase and the Mg#s decrease systematically from lherzolite to harzburgite to dunite. Magnesiochromites in the harzburgites and lherzolites are analogous to those from abyssal peridotites and MORB-like ophiolites, whereas those in clinopyroxenites and cumulate orthopyroxenites are typical of SSZ ophiolites, suggesting refertilization of the peridotites by metasomatic fluids/melts. This interpretation is supported by the “U-shaped”, chondrite-normalized rare earth element (REE) patterns of Purang mantle peridotites. Plots of TiO2 and Al2O3 vs. Mg# show that both the orthopyroxenes and clinopyroxenes overlap the fields of abyssal and SSZ peridotites indicating a transition from a MOR to a SSZ setting for the Purang peridotites.

Spinel peridotite, olivine websterite and the textural evolution of the Purang ophiolite complex, western Tibet

Spinel peridotite and associated olivine websterite form an ultramafic massif at the base of the Purang ophiolite complex of western Tibet. The spinel peridotites consist chiefly of harzburgites with lesser amounts of lherzolite and dunite. All of the peridotites are rich in MgO, but depleted in Al2O3, CaO and TiO2 relative to primary mantle values, indicating depletion by several episodes of partial melting. The olivine websterite was probably generated from evolved melts that had reached olivine saturation and that reacted with the host harzburgite. The evolution of the Purang ultramafic rocks from lherzolite through harzburgite and dunite to olivine websterite, indicates multistage melting and melt/rock reaction processes. Decompression-related textures such as exsolution lamellae of clinopyroxene and spinel in orthopyroxene, melting and melt/rock reaction textures, such as embayed, flame-like grains of spinel and partial chain spinel textures are widespread in the ultramafic rocks. Impregnation textures are reflected by the presence of late intergranular and interstitial clinopyroxene and spinel in the harzburgite, dunite and olivine websterite. Mineral textures vary from lherzolite to harzburgite and dunite to olivine websterite, and equilibrium temperatures of corresponding mineralogical assemblage increase as the degree of melt metasomatism or melt–rock reaction increase. Chromer spinels in the lherzolite with Cr#s (100Cr/(Cr+Al) of 26–33 may have formed beneath a mid-ocean ridge system or in an evolved back-arc basin, whereas spinel in the harzburgite, which has Cr#s of 39–57, is thought to record both abyssal and supra-subduction zone processes. Dunite and olivine websterite containing Cr-spinel with Cr#s of 60–64 and 52–87, respectively, reflect melt–rock reaction in a supra-subduction zone environment. Plots of TiO2 vs Al2O3 for spinel and Al2O3, TiO2 and Cr# vs Mg# for orthopyroxenes of the Purang ophiolite also support these conclusions. The Purang spinel peridotites thus provide a good example of multistage melt extraction, as well as melt/rock and metasomatic reactions in an ophiolitic mantle sequence.

High-resolution stratigraphy of the deep-water lower Cloridorme Formation (Ordovician), Gaspé Peninsula, based on K-bentonite and megaturbidite correlations

The Ordovician Cloridorme Formation is a thick foreland-basin turbidite succession that for several decades has served as a natural laboratory for the long-distance physical tracing and study of single turbidites. A robust temporal correlation of these deposits is a prerequisite for the evaluation of sedimentary processes. Published stratigraphic subdivisions of the lower part of the Cloridorme Formation have impeded rather than facilitated such studies because of errors in the physical correlation of contemporaneous deposits. Tracing of the deposits of exceptionally large gravity flows, known as "megaturbidites," was previously recognized as a useful stratigraphic tool. Here, we strengthen and revise the stratigraphic framework based on megaturbidites by considering nine widely traceable and geochemically fingerprinted tuffs (K-bentonites). Two discriminant functions incorporating the abundances of six trace elements (V, Sm, Nd, Th, Er, Zr) permit the unambiguous distinction of the lower four tuffs. The other tuffs can be successfully distinguished using bivariate plots of TiO2, Th, Sc, and Eu. The tracing and correlation of 71 megaturbidites and the nine K-bentonites permits a high-resolution subdivision of the lower Cloridorme Formation. Particularly thick megaturbidites mark the boundaries of three newly defined allostratigraphic members (St-Hélier Allomember, St-Yvon Allomember, and Petite-Vallée Allomember). This precise temporal framework shows that the stratigraphic heights of the contacts of lithostratigraphic members defined by other workers in 1969 and 1991 were miscorrelated by more than 400 m over short lateral distances!

The Range of Spinel Compositions in Terrestrial Mafic and Ultramafic Rocks

Compositional fields for spinels from a wide variety of mafic– a wide range of conditions from mafic and ultramafic ultramafic igneous rock types and tectonic environments have been magmas and, in the case of chromites, are often among determined from a global database of over 26 000 analyses. the first phases to crystallize. They also exhibit a wide These fields are defined using contoured data density plots based range of solid solution, the thermodynamics of which has on the spinel prism, and plots of TiO2 vs ferric iron, for mantle been studied extensively (O’Neill & Wall, 1987; Mattioli xenoliths, ophiolitic rocks, continental layered intrusions, alkalic & Wood, 1988; Wood, 1990; Sack & Ghiorso, 1991; and lamprophyric rocks, tholeiitic basalts, Alaskan ultramafic Poustovetov, 2000). They are relatively refractory and complexes and komatiites. Several trends appear regularly in the resistant to alteration, particularly compared with other various environments: a trend of widely variable Cr/(Cr + Al) high-temperature igneous minerals such as olivine. They at low Fe/(Mg + Fe) (the Cr–Al trend); increasing Fe, occur in a high proportion of terrestrial mafic and ultraFe/(Mg + Fe) and TiO2 at constant Cr/(Cr + Al) mafic rocks, and a very large volume of microprobe data (Fe–Ti trend); a trend found primarily in kimberlites, similar is available on their compositions. to Fe–Ti but at constant Fe/(Mg + Fe); and an unusual Publications on spinels (particularly chromites) have trend of increasing Al found only in layered intrusions. The routinely used compositional fields based on the spinel Cr–Al and Fe–Ti trends are both found to varying degrees in prism to compare populations of analyses. Some of tholeiitic basalts. The Cr–Al trend is prevalent in rocks that these fields have remarkable longevity, particularly those have equilibrated over a range of pressures, whereas the Fe–Ti defined for layered intrusions and Alpine peridotites by trend is dominantly due to low-pressure fractionation. The most Irvine (1967, 1977). Many new data have become availCr-rich chromites found in nature occur in boninites, diamondable in the last 20 years, however, and it has become bearing kimberlites, some komatiites and ophiolitic chromitites. apparent that a new compilation of data is necessary to Exceptionally reduced chromites are found in some komatiites reflect this. The prime purpose of this paper is to analyse and in ophiolitic chromitites. Detrital chromites from the a global database of about 26 000 spinel analyses from Witwatersrand conglomerates are of komatiitic provenance. terrestrial igneous and metamorphosed igneous rocks, and to extract from this database the characteristic compositional fields of spinels from the wide variety of magma types and tectonic environments in which they occur.

Processes controlling the distribution of Ti and Al in weathering profiles, siliciclastic sediments and sedimentary rocks

ABSTRACT The ratio of Ti to Al varies greatly in primary (igneous) source rocks. These elements are considered to be relatively immobile in most weathering regimes, so that TiO2:Al2O3 ratios have been used to investigate the provenance of sediments and sedimentary rocks. In modern weathering profiles that have undergone moderate weathering, Ti:Al ratios remain fairly constant so that siliciclastic sediments derived from them should have Ti:Al ratios like that of the source materials. Under extreme weathering conditions, however, the upper (most weathered) parts of profiles commonly show a marked increase in Ti:Al ratio that is thought to be due to preferential translocation of Al-rich phases. Under steady-state weathering conditions, one particular level of the profile may act as the main source of detrital material and may thus control the Ti:Al ratio of sediments produced from it. In a glacio-fluvial setting (minimum weathering, moderate sorting) there is considerable variation in Ti content but Al is nearly constant. This is due to concentration of Ti-bearing mafic minerals, such as biotite, in the fine fraction. In modern sediments derived from moderately weathered and sorted material, the Ti:Al distribution reflects mixing of Al- and Ti- enriched fine-grained materials with sands that are depleted in these elements. When a plot of TiO2 vs. Al2O3 is constructed for a suite of such sands and muds, the resultant trend differs significantly from that shown by a similar suite of unweathered glacio-fluvial sediments. Comparison of these results with data from sedimentary rock suites suggests that trends shown by plots of TiO2 vs. Al2O3 may provide insight into weathering and depositional history, in addition to their use as provenance indicators.