The thorite mineralization in the Madeira Sn-Nb-Ta world-class deposit (Pitinga, Brazil)

Hadlich, Ingrid Weber; Neto, Artur Cézar Bastos; Botelho, Nilson Francisquini; Pereira, Vitor Paulo

doi:10.1016/j.oregeorev.2019.01.004

Cited by 9 publications

(3 citation statements)

References 54 publications

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“…Zinc and S were incorporated into secondary sphalerite, and the remaining available S formed galena and pyrite. In the late hydrothermal stage, Fe contributed to the formation of hematite, surrounding all the previous formed minerals (Minuzzi et al ., 2005; Bastos Neto et al ., 2009; Hadlich et al ., 2019). Genthelvite crystallised during the transition between the magmatic and hydrothermal stages of pegmatite evolution, following the crystallisation of riebeckite and polylithionite.…”

Section: Discussionmentioning

confidence: 99%

Mn–Fe-rich genthelvite from pegmatites associated with the Madeira Sn–Nb–Ta deposit, Pitinga, Brazil: new constraints on the magmatic-hydrothermal transition in the albite-enriched granite system

Hadlich,

Bastos Neto,

Pereira

et al. 2024

MinMag

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Genthelvite from pegmatite veins hosted by the albite-enriched granite (ca.1.8 Ga) corresponding to the Sn–Nb–Ta (F, REE, Li, Zr, U, Th) Madeira deposit, Amazonas, Brazil was studied. Genthelvite, the exclusive Be-bearing mineral within the deposit, occurs as massive crystals of up to 4.7 cm in size. Compositions are homogeneous within individual crystals, although there is moderate variation in the overall composition reflecting relatively limited substitutions within the helvine–genthelvite–danalite solid-solution series, with relatively high Zn contents (36.96 to 49.45 wt.% ZnO), lower Mn contents (0.61 to 3.03 wt.% MnO), and variable Fe contents (2.10 to 10.94 wt.% FeO), completing an existing compositional gap in this system. Genthelvite formed in an alkaline and subaluminous environment, under stable conditions within the late-evolved fluids, at relatively high temperature (>400°C), in a reducing environment. The extremely high concentration of fluorine in the magma and the crystallisation of magmatic galena resulted in an effective reduction of H2S fugacity. This resulted in the stabilisation of genthelvite during the transition from the late magmatic to early hydrothermal stages of the albite-enriched granite evolution. The variability in Fe content within genthelvite is associated primarily with localised variations in the mineral assemblage (e.g. the presence of riebeckite and polylithionite). Genthelvite was altered by low-temperature aqueous fluids rich in F which resulted in the incorporation of Fe, Mn, Mg, Pb, Ba, Na, K, U and REE into the Zn2+ structural site and the allocation of excess Si, Al, Ti and P in the IVSi and IVBe structural sites. The substantial content of U and REE substituting for Zn, together with Si substituting for Be, is charge balanced by the presence of vacancies at the A site.

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Section: Discussionmentioning

confidence: 99%

Mn–Fe-rich genthelvite from pegmatites associated with the Madeira Sn–Nb–Ta deposit, Pitinga, Brazil: new constraints on the magmatic-hydrothermal transition in the albite-enriched granite system

Hadlich,

Bastos Neto,

Pereira

et al. 2024

MinMag

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“…Batuan dengan komposisi basaltik umumnya memiliki rata-rata konsentrasi Th sekitar 10,50 ppm [40,41] dan U sekitar 3,00 ppm [41,42]. Rata-rata konsentrasi tersebut akan semakin meningkat seiring dengan tingkat keasaman batuan.…”

Section: Evolusi Magma Dan Tektonikunclassified

“…Konsentrasi Th yang tinggi pada batuan mafik di daerah penelitian (Tabel 2) disebabkan oleh mekanisme pembekuan magma yang sangat ekstrim. Mekanisme tersebut terjadi akibat proses fraksionasi yang berjalan dengan sangat cepat [41,46]. Temperatur magma yang turun secara drastis akibat masuknya tambahan material dari luar sistem ke dalam magma menjadi penyebab terjadinya anomali tersebut.…”

Section: Evolusi Magma Dan Tektonikunclassified

Peralihan Rezim Tektonik: Implikasinya pada Konsentrasi Torium di Mamasa dan Tana Toraja, Sulawesi-Indonesia

Saputro¹,

Purwaningsih

Priadi

2020

EKSPLORIUM

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ABSTRAK Mamasa dan Tana Toraja secara geografis merupakan bagian dari lengan barat Pulau Sulawesi. Batuan-batuan mafik di daerah tersebut dan sekitarnya memiliki nilai laju radiasi tinggi dan anomali kandungan torium (Th). Penelitian ini bertujuan untuk mengetahui mekanisme tataan tektonik yang berperan dalam peningkatan konsentrasi Th. Enam sampel batuan dianalisis menggunakan analisis petrografi dan geokimia (AAS, ICP-MS, NA, dan XRF), dilengkapi dengan pentarikhan umur menggunakan metode 40K-40Ar pada sampel batuan terpilih. Pengamatan petrografi memperlihatkan kehadiran mineral plagioklas, olivin, piroksen, hornblenda, nefelin, dan alanit pada batuan yang diidentifikasi sebagai nefelin-basanit, basalt, trakhibasalt, dan gabro. Sejumlah tekstur yang tampak pada batuan tersebut mengindikasikan kontaminasi dan perubahan kondisi tektonik. Analisis geokimia menunjukkan bahwa nefelin-basanit, basalt, trakhibasalt, dan gabro (absarokit) terbentuk pada batas kontinental aktif (ACM) yang sedang mengalami transisi dari subduksi aktif (penunjaman ke arah barat) menjadi post-subduksi. Perubahan tataan tektonik membuat magma membeku pada kondisi yang sangat ekstrim. Proses pembekuan magma diinterpretasikan terjadi pada umur sekitar 13,10-11,02 Ma. Mekanisme tersebut berperan penting terhadap terjadinya peningkatan konsentrasi torium di Mamasa dan Tana Toraja.ABSTRACT Mamasa and Tana Toraja geographically are part of the western arm of Sulawesi Island. The mafic rocks in these areas and their surroundings have high radiation dose rate and thorium (Th) anomaly content. This research aim is to determine tectonic setting mechanism which play the important role on the increasing of Th concentration. Six rock samples were analysed using petrography and geochemical analyses (AAS, ICP-MS, NA, and XRF) completed with the 40K-40Ar dating on selected rock samples. Petrography observations show plagioclase, olivine, pyroxene, hornblende, nepheline, and allanite minerals presence in the rocks which identified as nepheline-basanite, basalt, trachybasalt, and gabbro. Numbers of texture appearances in the rocks indicate contamination and changes on tectonic setting. Geochemistry analysis shows that nepheline-basanite, basalt, trachybasalt, and gabbro (absarokite) were formed at the active continental margin (ACM), which is undergoing active subduction (westward subduction) to post-subduction transition. The changing of tectonic setting made magma solidify in extreme conditions. The magma solidify process is interpreted to occur at the age of 13.10-11.02 Ma. These mechanisms play an important role for the increase of thorium concentration in Mamasa and Tana Toraja.

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Thorium Metallogeny in U-Cu-REE bearing Singhbhum Shear Zone, Eastern India

Sinha

Akhila

Gupta

et al. 2022

Journal of the Geological Society of India

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The long arcuate Singhbhum Shear Zone (SSZ) of around 160 km length having roughly an E-W trend hosts many uranium deposits and working uranium mines viz., Mohuldih, Bandhuhurang, Turamdih, Narwapahar, Bhatin, Jaduguda and Bagjata from west to east in addition to Cu deposits viz., Rakha, Mosabani etc. REE is well known from Kanyaluka area. Recent sub-surface exploration for uranium by AMD unravelled occurrence of thorite (ThSiO4)-bearing bands in a number of locations in western, central and eastern sectors of uranium mineralisation in SSZ, spanning over the entire shear zone. Thorite is observed in various host rocks involving metapelites of Dhanjori and Singhbhum Group and also in the Soda Granite/ feldspathic schist unit emplaced along the shear zone at the contact between the two groups. The individual lithounits that host thorite-bearing bands are restricted along the Singhbhum Shear Zone and include feldspathic schists (possible derivative of Soda Granite), albite veins, quartz-chlorite schists, quartz-biotite schists and sericite/muscovite-quartz schists. The thorite bearing zones transgresses lithology, stratigraphy as well as uraniferous zones along the shear zone evidently placing them as epigenetic hydrothermal mineralisation possibly later to major uranium metallogeny. Thorite occurs as discrete, rounded as well as subhedral to euhedral grains in various metapelites. They also form veins of their own besides occurring as phases within veins of albite and magnetite-apatite along the shear zone. Such multiple modes of occurrence and varied associated mineralogy suggest hitherto unknown thorium related hydrothermal mineralisation in SSZ. Presence of secondary thorium phases such as brockite (Ca-Th-phosphate) as well as post tectonic vein-type occurrence, points towards the mobility of thorium under a hydrothermal regime as well. However, present study thus, for the first time, establish the occurrence of thorite along with REE-Th minerals showing definite evidences of thorium mobilisation in several sectors of the well know U-Cu province of Singhbhum Shear Zone. Thorium-REE mobility is a widely understudied domain and the present findings place the SSZ as an ideal ground for exploring the concept with more understanding of this metal.

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The thorite mineralization in the Madeira Sn-Nb-Ta world-class deposit (Pitinga, Brazil)

Cited by 9 publications

References 54 publications

Mn–Fe-rich genthelvite from pegmatites associated with the Madeira Sn–Nb–Ta deposit, Pitinga, Brazil: new constraints on the magmatic-hydrothermal transition in the albite-enriched granite system

Mn–Fe-rich genthelvite from pegmatites associated with the Madeira Sn–Nb–Ta deposit, Pitinga, Brazil: new constraints on the magmatic-hydrothermal transition in the albite-enriched granite system

Peralihan Rezim Tektonik: Implikasinya pada Konsentrasi Torium di Mamasa dan Tana Toraja, Sulawesi-Indonesia

Thorium Metallogeny in U-Cu-REE bearing Singhbhum Shear Zone, Eastern India

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