An investigation of Fe‐Ti, V in the north‐east Karbi Hills, Shillong Plateau, north‐east India: Implication for mineralization

Abstract

The Kulamati gabbro-anorthosite complex in the Karbi Hills of the Shillong Plateau, north-east India is a newly discovered stratified Fe-Ti-V-bearing magmatic body that has been classified as a titano-magnetite ore. The host gabbro-anorthosite is found intruded into the Mesoproterozoic Shillong Group. The stratified Fe-Ti-V oxide body consists mostly of magnetite-rich and magnetite-poor layers. The magnetite-rich bands are composed of titanomagnetite, haematite, ilmenite, and coulsonite with minor Alspinel, while the mineral constituents of silicate bands contain plagioclase, clinopyroxene, olivine, apatite, and chlorite. Titaniferous magnetites display a wide variety of subsolvus features, including Al-spinel-magnetite-ulvöspinel exsolutions and crystallographically oriented ilmenite exsolutions, but magnetites are exclusively vanadiferous. Comprehensive chemical analyses show that the ore is rich in TiO 2 (10.98-12.78 wt%) and V 2 O 5 (1.32-1.47 wt%). Ti is attributed by the presence of rutile, titanite, and ilmenite, while V is attributed by coulsonite as a solid solution component in the titanomagnetite. It records moderate to high Al 2 O 3 (4.51-5.46 wt%), with enrichment of FeO and Fe 2 O 3 (26.22-28.32 wt% and 39.34-42.86 wt%, respectively), which can be attributed to the presence of magnetite-spinel-ulvospinel. Higher Fe 2 O 3 and lower FeO are indicative of oxidizing conditions of the ore-forming environment. The rare earth element (REE) patterns have (La/Yb) N and (Ce/Yb) N ratios comparable to an evolved basaltic melt, with light REE being enriched compared to heavy REE and a positive Eu anomaly. The electron probe micro analyser data of magnetite is conformable with the bulk chemistry, and shows consistently high FeO (70.87-88.06 wt%), Cr 2 O 3 (1.02-2.44 wt%), TiO 2 (0.16-6.20 wt%), and V 2 O 3 (1.47-2.26 wt %), with trace amounts of Al, Si, Mg, Mn, and PGE. As per targeted parameters, the ore occurrence distinctly belongs to a stratified Fe-Ti-V class, where alternate thick (>1.0 m) and thin (<20 cm) strata resulted from the late magmatic crystallization of the original tholeiitic composition.

Origin and evolution of vanadium‐rich oxide and titanite phases in lamprophyre and mafic dykes from the Nuapada diamondiferous Lamproite field, BastarCraton‐EasternGhats Mobile belt contact, India: Metallogenic and geodynamic implications

“…Within the Indian context, occurrences of vanadium are very scarce, and limited information is available on the aspects of the origin of V‐bearing phases (Kumar et al, 2021; Majumdar et al, 2021; Saha et al, 2010) (Table 1). A comparative table on the occurrences and reports of vanadium from the Indian Shield is compiled in Table 2.…”

Introduction, Part 2—Geodynamic evolution of Eastern Himalaya and Indo‐Myanmar orogenic belts: Advances through interdisciplinary studies

“…This Special Issue‐ Part 2 is a continuation of earlier Special Issue‐ Part 1 published in vol. 57 (2), of Geological Journal , which contained 26 research articles (Ao & Satyanarayanan, 2022; Baral et al, 2022; Bhowmik et al, 2022; Bora, Borah, et al, 2022; Bora, Mukherjee, et al, 2022; Deb & Ray, 2022; Devi & Singh, 2022; Devrani et al, 2022; Doley et al, 2022; Gogoi et al, 2022; Gupta et al, 2022; Hazarika & Kayal, 2021; Imtisunep et al, 2022; Liu et al, 2022; Luirei et al, 2022; Lukram & Tandon, 2022; Bidyananda et al, 2022; Majumdar, Gogoi, & Ghatak, 2022; Majumdar, Gogoi, Ghatak, Saikia, et al, 2022; Mukherjee et al, 2022; Pebam et al, 2021; Rashid et al, 2022; Saikia et al, 2022; Singh and Kshetrimayum, 2021; Singh, Guruaribam, Singh et al, 2022; Singh, Singh, Singh, et al, 2022; Srivastava, 2021; Srivastava & Kichu, 2021). Figure 2 displays the area of study of 29 papers included in this Special Issue 2.…”

“…Geological map of Eastern Himalaya, Indo‐Myanmar orogenic belt, northern, Central Myanmar, and adjacent areas (modified after Mitchell et al, 2007; Searle et al, 2007; Y. R. Singh, Singh, Singh, et al, 2022). Locations of study area presented in the issue include 1/S2: Kundu and Hazarika (2022); 2/S2: Y. R. Singh, Singh, Singh, et al (2022); 3/S2: Rawat and Luirei (2022); 4/S2: Kayal et al (2022); 5/S2: Choudhury et al (2022); 6/S2: N. M. Sharma et al (2022); 7/S2: Goswami, Gogoi, et al (2022); 8/S2: Bikramaditya et al (2022); 9/S2: Goswami, Kalita, et al (2022); 10/S2: Joshi (2022); 11/S2: Jha and Sharma (2022); 12/S2: Shukla et al (2022); 13/S2: Khonglah et al (2022); 14/S2: Ali and Duarah (2022); 15/S2: Mohanty et al (2022); 16/S2: Chanu et al (2022); 17/S2: Majumdar, Gogoi, and Ghatak (2022); Majumdar, Gogoi, Ghatak, Saikia, et al (2022); 18/S2: Ding et al (2022); 19/S2: Ghose et al (2022); 20/S2: Hussain and Dey (2022); 21/S2: Ozukum et al (2022); 22/S2: Jamir et al (2022); 23/S2: Chaubey et al (2022); 24/S2: Bora, Borah, et al (2022); Bora, Mukherjee, et al (2022); 25/S2: Khuman and Ibotombi (2022); 26/S2: Y. R. Singh, Singh, Singh, et al (2022); 27/S2: Thokchom and Kshetrimayum (2021); 28/S2: Barman et al (2022); 29/S2: V. Sharma and Biswas (2022)…”