| 1. |
- Al-Ani, Thair, et al.
(författare)
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Crystal Chemistry and Geochronology of Thorium-Rich Monazite from Kovela Granitic Complex, Southern Finland
- 2019
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Ingår i: Natural Resources. - USA : Scientific Research Publishing. - 2158-706X .- 2158-7086. ; 10:6, s. 230-269
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Tidskriftsartikel (refereegranskat)abstract
- Abundant porphyritic granites, including Grt-bearing and Bt-bearing porphyritic granites, and porphyritic potash-feldspar granite (trondhjemite-granitic composition) are widely distributed within the Kovela granitic complex Southern Finland, which associated with monazite-bearing dikes (strong trondhjemite composition). The investigated monazite-bearing dikes are dominated by a quartz + K-feldspar + plagioclase + biotite + garnet + monazite assemblage. The monazite forms complexly zoned subhedral to euhedral crystals variable in size (100 - 1500 μm in diameter) characterized by high Th content. The chemical zoning characterised as: 1) concentric, 2) patchy, and 3) intergrowth-like. Textural evidence suggests that these accessory minerals crystallized at an early magmatic stage, as they are commonly associated with clusters of the observed variations in their chemical composition are largely explained by the huttonite exchange , and subordinately by the cheralite exchange with proportions of huttonite (ThSiO4) and cheralite [CaTh(PO4)2] up to 20.4% and 9.8%, respectively. Textural evidence suggests that these monazites and associated Th-rich minerals (huttonite/thorite) crystallized at an early magmatic stage, rather than metamorphic origin. The total lanthanide and actinide contents in monazite and host dikes are strongly correlated. Mineral compositions applied to calculate P-T crystallization conditions using different approaches reveal a temperature range of 700°C - 820°C and pressure 3 - 6 kbars for the garnet-biotite geothermometry. P-T pseudo-section analyses calculated using THERMOCALC software for the bulk compositions of suitable rock types, constrain the PT conditions of garnet growth equilibration within the range of 5 - 6 kbars and 760°C - 770°C respectively. Empirical calculations and pseudo-section approaches indicate a clockwise P-T path for the rocks of the studied area. 207Pb/206Pb dating of monazite by LA-MC-ICPMS revealed a recrystallization period at around 1860 - 1840 Ma. These ages are related to the tectonic-thermal event associated with the intense crustal melting and intra-orogenic intrusions, constraining the youngest time limit for metamorphic processes in the Kovela granitic complex.
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| 2. |
- Al-Ani, Thair, et al.
(författare)
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Mineralogical and Petrographic Characteristics of Indium and REE-Bearing Accessory Phases in the Kymi Granite Stock, Southern Finland
- 2018
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Ingår i: Natural Resources. - : Scientific Research Publishing. - 2158-706X .- 2158-7086. ; 9:2, s. 23-41
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Tidskriftsartikel (refereegranskat)abstract
- The Wiborg rapakivi batholith (1.64 Ga) in southeastern Finland with docu-mented occurrences of REE, indium and Zn-Cu-Pb sulphide mineralization was studied. Hydrothermal greisen and quartz vein type Fe-Sn and Zn-Cu-Pb are found in the Kymi granite stock as intrusions. They are enriched with in-dium and rare earth elements, with roquesite (CuInS2) being a major indium- carrier, whereas monazite (Ce), allanite (Ce), bastnäesite (Ce), xenotime-(Y) and thorite are the main REE carriers. Combination of optical and field emis-sion scanning electron microscopy (FE-SEM) and electron probe microanaly-sis (EPMA) were used to study the indium and REE-bearing mineral assem-blages. EPMA of roquesite found in galena had a composition of 26.16% S, 0.02% Fe, 25.06% Cu, 0.03% Zn, 1.06% As, 0.31% Sb and 47.14% In. Substitu-tion reaction Pb2+S2− ↔ Cu+In3+S2− is the cause of the incorporation of indium in the galena structure. The majority of the LREE are carried by monazite, bastnäesite and allanite, and the HREE by xenotime and zircon. There is a partial solid solution between monazite and xenotime with minor or trace amounts of LREE in xenotime grains (6.0 wt%). LREE (>95 mol% LREE) and less than 5 mol% HREE + Y reflects the enrichment of chondrite-normalized REE of the monazite grains of the Kymi granite stock. The xenotime grains (small and irregular) main composition contains 71 - 76 mol% YPO4, 16 - 27 mol% HREE, and 6 - 8 mol% LREE. It is believed that indium and REE-mineralization presence is due to the combination of magmatic and postmagmatic processes, particularly at later stages by fluid fractionation.
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| 3. |
- Al-Ani, Thair, et al.
(författare)
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Trace elements in water and sediments of the Tigris river, Baghdad City, Iraq
- 2014
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Ingår i: Journal of Environmental Hydrology. - 1058-3912 .- 1996-7918. ; 22
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Tidskriftsartikel (refereegranskat)abstract
- Industrial, agricultural and rural activities may result in pollution of watercourses with elevated trace metal concentrations and implications for water supply and ecosystem functioning. The concentration of the trace metals Fe, Mn, Zn, Co, Pb, Cu, and Cd in the water and clay fractions (<2μm) of the bank sediments of River Tigris in Baghdad city were determined. Dissolved trace metals concentrations were far below the upper permissible limits during 2012-2013. There was no consistent pattern between element concentrations and river discharge. Seasonal interrelations between water and sediments were most obvious for Fe that decreased in both environments with rising flows during autumn. Although independent of discharge, Mn in water and sediments often followed each other at all stations. Zinc, however, increased in the sediments and decreased in the water with discharge. The clay fractions were slightly to strongly enriched in trace metals with the gradient Co > Fe > Zn > Mn > Cu suggesting absorption of the metals on sediment substrate.
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