Geochemistry of niobium and tantalum

Parker, Raymond Laurence; Fleischer, Michael

doi:10.3133/pp612

Cited by 33 publications

(15 citation statements)

References 42 publications

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“…Niobium and Ta are chemically very similar elements. Both are at trace levels in pyroxene, amphibole, biotite, rutile, ilmenite, sphene, cassiterite and zircon, and thus in heavy minerals (Parker and Fleischer, 1968). The Guryul Nb/Ta ratios are generally below 20 and compatible with reference sediments, but there are a few very high values above 50 in Khunamuh E2 and 3, which are superchondritic (Figure 19).…”

Section: Trace Elementsmentioning

confidence: 93%

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Palaeoenvironments and elemental geochemistry across the marine Permo‐Triassic boundary section, Guryul Ravine (Kashmir, India) and a comparison with other North Indian passive margin sections

Brookfield

Stebbins

Williams

et al. 2019

The Depositional Record

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The Guryul Permian-Triassic sediments were deposited on a passive margin in a partially enclosed basin, at a latitude of about 45°S along the southern margin of the Neotethys Ocean. The closest modern analogy is the Japan Sea rotated into a southern hemisphere orientation. Guryul element variations are subdued, mostly lithological, and take place across the change from the dominantly sandy shallow-water Permian Zewan Formation into the dominantly shaly deeper-water latest Permian-Triassic Khunamuh Formation, and not at the palaeontological Permian-Triassic boundary.The overall geochemistry of the Guryul sediments is very similar to that of the Ulleung Basin in the Japan Sea, where the sediments are 40%-60% eolian from loess and redeposited loess in the North China Basin. The overall Guryul geochemistry indicates that the sediments were derived from dominantly silica-rich continental rather than silica-poor sources although with some more silica-poor inputs at times. Element ratios suggest increasing aridity and wind abrasion across the Permian-Triassic boundary. Various geochemical redox proxies suggest mainly oxic depositional conditions, with episodes of anoxia, but with little systematic variation across the extinction boundary. Productivity proxies suggest a slight decrease across the Permian-Triassic boundary, and at least one more decreased interval in the Early Triassic. The similar geochemistry of other localities indicate that the Guryul geochemical changes are regional in extent and representative of the North Indian Permian-Triassic passive margin. The lack of consistent element geochemical changes across the boundary accompanied by significant C, S, and other isotopic changes suggests that atmospheric and oceanic chemistry rather than physical changes, such as provenance, climate and sea-level changes, drove the Permian-Triassic environmental changes and extinctions at least on the mid-latitude Tethyan shelf of northern India. K E Y W O R D S Extinction, geochemistry, Kashmir, Permian-Triassic 76 | BROOKFIELD Et aL. F I G U R E 1 Late Permian palaeogeography (courtesy of Chris Scotese): Early Triassic "dead zone" from Sun et al. (2012); Winds from Kiehl and Shields (2005). Locations of cited Permo-Triassic boundary section in open circles with names in bold face 78 | BROOKFIELD Et aL. F I G U R E 8 Biostratigraphy of the Guryul Permian-Triassic boundary section showing stratigraphic range of fossils and number of species in each subdivision (data from Nakazawa et al., 1975). Bryo -bryozoans. Gastr -gastropods. Note that there is little extinction at the Zewan-Khunamuh Formation boundary and the main extinction (and new species appearance) is at the FAD of Hindeodus parvus, and the first inferred anoxic level marked by pyrite framboids.

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Section: Trace Elementsmentioning

confidence: 93%

“…Both are at trace levels in pyroxene, amphibole, biotite, rutile, ilmenite, sphene, cassiterite and zircon, and thus in heavy minerals (Parker and Fleischer, 1968). Both are at trace levels in pyroxene, amphibole, biotite, rutile, ilmenite, sphene, cassiterite and zircon, and thus in heavy minerals (Parker and Fleischer, 1968).…”

Section: Trace Elementsmentioning

confidence: 99%

Palaeoenvironments and elemental geochemistry across the marine Permo‐Triassic boundary section, Guryul Ravine (Kashmir, India) and a comparison with other North Indian passive margin sections

Brookfield

Stebbins

Williams

et al. 2019

The Depositional Record

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“…Two other elements we examined as provenance indicators are Ti and Nb. Although Ti is found in low concentrations in a few primary minerals (e.g., biotite, hornblende, zircon), it is a major constituent in sphene, ilmenite, and rutile (Parker and Fleischer, 1968). Niobium commonly substitutes for Ti and thus Ti/Nb ratios will vary primarily with the mineralogy and source rocks of Ti-bearing heavy minerals.…”

Section: Use Of K/rb and Ti/nb As Provenance Indicatorsmentioning

confidence: 99%

Origin and paleoclimatic significance of late Quaternary loess in Nebraska: Evidence from stratigraphy, chronology, sedimentology, and geochemistry

Muhs

Bettis

Aleinikoff

et al. 2008

Geological Society of America Bulletin

127

104

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Rachel, "Origin and paleoclimatic signifi cance of late Quaternary loess in Nebraska: Evidence from stratigraphy, chronology, sedimentology, and geochemistry" (2008 The spatial variability of particle size abundances in Peoria Loess shows a northwest-to-southeast fi ning in Nebraska, consistent with maps of previous workers that show a northwest-to-southeast thinning of loess. These observations indicate that paleowinds that deposited the loess were from the west or northwest and that the source or sources of Peoria Loess lay to the west or northwest.New mineralogical and geochemical data indicate that the most important sources of loess were likely Tertiary siltstones of the White River and Arikaree Groups, silt facies of Pliocene eolian sediments, and small contributions from Pierre Shale. It is likely that fi ne-grained silts were transported episodically through the Nebraska Sand Hills from

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“…The early report of Parker and Fleischer (1968) noted that in fluorine-rich environment, Nb and Ta could combine with fluorine to form ionic complexes, and their fractionation result from Ta-fluorine complexes being more mobile and stable than precursor and metamictization of HREE-bearing minerals such as zircon may supply the additional HREE to the altered granite. The microprobe analysis of the altered granite indicates that secondary fluorite (Fig.…”

Section: High Field Strength Elements (Hfse)mentioning

confidence: 99%

Geochemical and genetical constraints on rare metals mineralization at the central Eastern Desert of Egypt.

El-Kammar¹,

Salman²,

Shalaby³

et al. 2001

Geochem. J.

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Rare metals mineralization in Jabal Gattar, N. E. Egypt, occurs at the sheared tectonic contact between a younger granite and Hammamat sediments. The contact is affected by a local reverse fault directed N75°E and dipping 45°SSE. The Hammamat sediments consist substantially of rhythmic siltstones and immature greywackes. The paragenetic history of the mineralized sediments involves many types of alteration, such as dissolution of primary quartz (episyenitization), sericitization, albitization, hematization, pyritization, silicification, kaolinization and bleaching. The calculation of the mass-balance indicates preferential mobilization of REE, Rb, Cs, Be and S from Gattar granite to Hammamat sediments in the alteration zone. The elements; U, Y, W, Nb, Cu, Pb, Sb and Zn are enriched in both granite and sediments, but with higher magnitude for the latter. The hematized sediments are generally better accumulators for rare metals.The Gattar granite is classified as a meta-aluminous leucogranite, containing low Ca and high alkali. The low Ba and Sr and the high REE + Y reflect a highly fractionated (low P) A-type granite. The mineralized granite is affected by several metasomatic alterations. The mineralization causes enrichment in the content of U, Nb, W, Y and the chalcophile elements. The REE content displays portioning towards preferential mobilization of the LREE to the adjacent mineralized Hammamat sediments while higher quotient of the HREE is adopted within the secondary fluorite. The volume loss of granite due to leaching reactions (e.g., episyenitization) causes apparent enrichment of the immobile elements such as Sc, Th and Zr.The mineralization was caused by alkaline and oxidizing hot fluids, with contribution of meteoric water volume heated by convection. The hot fluids flowed up along ENE-WSW and NE-SW faults to cause a rather complicated series of metasomatic reactions. The rare metals were mobilized from the younger granite pluton of Gattar and concentrated in the sheared tectonic contact. The reaction of the mineralizing solutions with the wall rocks and the pseudomorphic oxidation of pyrite caused reduction and fixation of uranium. The study area can be considered as a possible potential deposit for U, REE + Y and other rare metals as well.wide spread in Sinai and the Eastern Desert of Egypt. They represent the magmatic activity making the end of the cratonization process of the PanAfrican orogeny and many of them are affected by post magmatic deuteric and hydrothermal alterations associated in many places by rare metals mineralization. These post-orogenic discordant massive younger granite plutons are high in SiO 2 , low in Ca and Mg and have low 87 Sr/ 86 Sr (Rogers and Greenberg, 1983). The younger gran-

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Geochemistry of niobium and tantalum

Cited by 33 publications

References 42 publications

Palaeoenvironments and elemental geochemistry across the marine Permo‐Triassic boundary section, Guryul Ravine (Kashmir, India) and a comparison with other North Indian passive margin sections

Palaeoenvironments and elemental geochemistry across the marine Permo‐Triassic boundary section, Guryul Ravine (Kashmir, India) and a comparison with other North Indian passive margin sections

Origin and paleoclimatic significance of late Quaternary loess in Nebraska: Evidence from stratigraphy, chronology, sedimentology, and geochemistry

Geochemical and genetical constraints on rare metals mineralization at the central Eastern Desert of Egypt.

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