Cu and Zn isotope fractionation during extreme chemical weathering

Little, Susan H.; Munson, Sophie; Prytulak, Julie; Coles, Barry J.; Hammond, Samantha J.; Widdowson, Mike

doi:10.1016/j.gca.2019.07.057

Cited by 58 publications

(31 citation statements)

References 145 publications

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“…Interestingly, Zn isotope ratios from Gamsberg are hardly fractionated (Foulkes, 2014), which can only be explained by a redox‐driven process because Zn is non redox‐sensitive. Comparable isotopic characteristics have been described from Indian laterites that have been affected by intense supergene alteration (Little et al., 2019). Moreover, strata‐bound peraluminous rocks, which underly the mineralization in places, can be explained by intense chemical weathering (Willner et al., 1990).…”

Section: Interpretation and Discussionsupporting

confidence: 56%

Pre‐Klondikean oxidation prepared the ground for Broken Hill‐type mineralization in South Africa

et al. 2020

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New Cu isotope data obtained on chalcopyrite from the Black Mountain and the Broken Hill deposits in the medium‐ to high‐grade metamorphic Aggeneys‐Gamsberg ore district (South Africa) require a revision of our understanding of the genesis of metamorphic Broken Hill‐type massive sulphide deposits. Chalcopyrite from both deposits revealed unusually wide ranges in δ65Cu (−2.41 to 2.84‰ NIST 976 standard) in combination with distinctly positive mean values (0.27 and 0.94‰, respectively). This is interpreted to reflect derivation from various silicate and oxide precursor minerals in which Cu occurred in higher oxidation states. Together with the observation of a typical supergene base metal distribution within the deposits and their spatial association with an unconformity only meters above the ore horizon, our new data are best explained by supergene oxidation of originally possibly SEDEX deposits prior to metamorphic sulphide formation, between the Okiepian (1,210–1,180 Ma) and Klondikean (1,040–1,020 Ma) orogenic events.

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Section: Interpretation and Discussionsupporting

confidence: 56%

Pre‐Klondikean oxidation prepared the ground for Broken Hill‐type mineralization in South Africa

et al. 2020

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“…However, there is no significant relationship between the two parameters (Figure 4e), indicating that the impact of freshwater input may not be the main reason for the seasonal change in skeletal δ 66 Zn. Even so, it should be noted that Zn content and δ 66 Zn in river water may change depending on climatic conditions and weathering mechanisms (e.g., Little et al., 2019), so the explanation on the correlation between coral δ 66 Zn and river runoff should be cautious.…”

Section: Discussionmentioning

confidence: 99%

A Pilot Study on Zinc Isotopic Compositions in Shallow‐Water Coral Skeletons

Xiao

Deng

Wei

et al. 2020

Geochem Geophys Geosyst

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“…The Pearson's correlation analysis reveals statistical relationships between DTPA metal extractions, elements (Al 2 O 3 , Fe 2 O 3 , MnO) and the CIA, the latter two reflecting bulk soil mineralogy (Table 4). However, the bio-availability of Zn and Cu is also controlled by TOC and both essential metals are commonly complexed by organic matter in weathered substrate in India [33,64].…”

Section: Zinc Cu and Fe And The Importance Of Organic Carbonmentioning

confidence: 99%

The role of pedogenesis and natural fertiliser as vectors for essential metal content in agricultural topsoils, Central India

2021

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Essential trace metals are well known for their environmental toxicity and for being part of complex bio-chemical cycles. Their role as critical micronutrients, delivering vital health benefits, is less widely discussed and understood, holding back strategies for combatting malnutrition. Crops grown on many Indian soils suffer from deficiencies in essential metals, notably iron (Fe), zinc (Zn), and molybdenum (Mo). The list of deficient metals will likely grow due to increasing future crop demand. Geostatistical analysis of soils and farmyard manure (FYM), the predominant fertiliser, implies that residual oxide minerals carry high concentrations of the essential trace metals Fe, Zn, copper (Cu), chromium (Cr), nickel (Ni), cobalt (Co), manganese (Mn) not only in soil but also in FYM (especially Fe, Cr, Cu, Co and Ni). A geochemical survey across a road traverse of 600 km, encompassing an area of c. 15,000 km2, was conducted in Central India to evaluate reported essential metal deficiency in key agricultural topsoils. Importantly, our evaluation of the element cycling in this system reveals that despite high bulk concentrations, some key metals remain bio-unavailable. In effect, the existence of refractory (weathering-resistant) oxides is likely a significant factor for deficiency symptoms in the soil–plant-fertiliser cycle. Further, mass balance calculations of the bioavailable pool of metals imply that only Fe and Mn are present in sufficient quantities to combat deficiency problems. Notwithstanding this limitation of FYM, its high organic carbon content, as well as its importance for Zn, Cu and Fe, validates its traditional use to maintain the fertility and physical condition of Indian topsoils.

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Cu and Zn isotope fractionation during extreme chemical weathering

Cited by 58 publications

References 145 publications

Pre‐Klondikean oxidation prepared the ground for Broken Hill‐type mineralization in South Africa

Pre‐Klondikean oxidation prepared the ground for Broken Hill‐type mineralization in South Africa

A Pilot Study on Zinc Isotopic Compositions in Shallow‐Water Coral Skeletons

The role of pedogenesis and natural fertiliser as vectors for essential metal content in agricultural topsoils, Central India

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