Scapolite: a tracer for the initial lead isotopic composition in sulfide deposits with later additions of radiogenic lead

Romer, Rolf L.; Martinsson, Olof; Perdahl, Jan-Anders

doi:10.1007/bf00225404

Cited by 3 publications

(1 citation statement)

References 14 publications

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“…via Sr and Nd isotopes). There are few data available concerning trace element uptake by scapolite (Shaw, ; Romer et al., ; Satish‐Kumar et al ., ) and there is a need to better understand the major element compositional and environmental (e.g. P , T ) controls on trace element incorporation.…”

Section: Discussionmentioning

confidence: 99%

Cl/Br of scapolite as a fluid tracer in the earth's crust: insights into fluid sources in the Mary Kathleen Fold Belt, Mt. Isa Inlier, Australia

Hammerli

Spandler

Oliver

et al. 2013

Journal Metamorphic Geology

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A combination of analytical methods, including trace element analysis of Br in scapolite by LA-ICP-MS, was employed to unravel the fluid-rock interaction history of the Mary Kathleen Fold Belt of northern Australia. Halogen ratios in the metamorphic and hydrothermally derived scapolite from a range of rock-types record interaction between the host rocks and magmatic-hydrothermal fluids derived from granite plutons and regional metamorphism. The results show that halite-dissolution supplied at best only minor chlorine to fluids in the Fold Belt. Chlorine/bromine ratios in metamorphic scapolite indicate that fluids were dominantly derived from basinal brines formed from sub-aerial evaporation of seawater beyond the point of halite saturation. This bittern fluid infiltrated the underlying sedimentary sequences prior to regional metamorphism. Zoned scapolite in a major late metamorphic mineralized shear-zone records three discrete pulses of magmatic and metamorphic fluid, and it is suggested that fluid mixing may have assisted mineralization along and around this shearzone. As a crucial prerequisite for halogen fluid tracer studies using scapolite, we find in our samples that Cl and Br do not fractionate when incorporated in scapolite. Furthermore, unaltered rims of heavily retrogressed scapolite show indistinguishable Cl/Br signatures compared with fresh grains from the same sample indicating retrograde metamorphism did not significantly affect Cl and Br signatures in scapolite group minerals.

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Section: Discussionmentioning

confidence: 99%

Cl/Br of scapolite as a fluid tracer in the earth's crust: insights into fluid sources in the Mary Kathleen Fold Belt, Mt. Isa Inlier, Australia

Hammerli

Spandler

Oliver

et al. 2013

Journal Metamorphic Geology

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Metal source and tectonic setting of iron oxide-copper-gold (IOCG) deposits: Evidence from an in situ Nd isotope study of titanite from Norrbotten, Sweden

Storey

Smith

2017

Ore Geology Reviews

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Titanite occurs as a widespread accessory phase in mineralized zones and alteration associated with iron oxide-copper gold (IOCG) and iron oxide-apatite (IOA) deposits of Norrbotten County, Sweden, and is a major host of the REE in these deposits. In situ analyses of Sm-Nd isotope ratios in titanites previously analysed for U-Pb geochronology and trace element composition confirms previous interpretations of grain scale isotopic heterogeneity. Initial Nd-isotope ratios expressed relative to CHUR range from ~-3 to -8 in IOA deposits, from ~-1 to -9 in IOCG deposits, and from +2 to -4 in the most Cu-rich, deformed IOCG deposits of the Nautanen Deformation zone. Within individual IOA deposits at Valkommen (Malmberget), from -1.4 to -5.7 in grain cores, and -7.2 to -8.2 in grain rims rim at Gruvberget; and from -3.0 to -6.0 in grain cores and from -5.8 to -7.1 in grain rims at Luossavaara. In IOCG deposits at Rakkurijärvi IOCG dpeosits at Nautanen from -1.3 to -2.3. These values are consistent with the derivation of the REE, and potentially economically enriched metals, from the local volcanic sequence, either via granitic melts, or directly by leaching by metasomatic fluids. The most Cu-rich deposits reflect the involvement of more basic protoliths. The age distribution of these deposits suggest IOA deposit formation during the collisional phase of the Svecofennian orogeny (~1.9-1.8 Ga), and IOCG mineralization during this phase and during post-orogenic collapse (~1.8-1.7 Ga), whilst model ages indicate the ultimate enrichment of the continental crust in these metals during pre-collisional extensional and subduction-related basic magmatism. These processes underscore the importance of continental cycles both in producing the preserved geological record of orogenic ore deposition, and in the generation of fertile continental crust, from which metals can be mobilised by subsequent events.Nd varies relative to CHUR: from -3.1 to -4.0Nd varies from -6.1. to -7.1, and in deformed IOCG dpeosits at Nautanen from -1.3 to -2.3. These values are consistent with the derivation of the REE, and potentially economically enriched metals, from the local volcanic sequence, either via granitic melts, or directly by leaching by metasomatic fluids. The most Cu-rich deposits reflect the involvement of more basic protoliths. The age distribution of these deposits suggest IOA deposit formation during the collisional phase of the Svecofennian orogeny (~1.9-1.8 Ga), and IOCG mineralization during this phase and during post-orogenic collapse (~1.8-1.7 Ga), whilst model ages indicate the ultimate enrichment of the continental crust in these metals during pre-collisional extensional and subduction-related basic magmatism. These processes underscore the importance of continental cycles both in producing the preserved geological record of orogenic ore deposition, and in the generation of fertile continental crust, from which metals can be mobilised by subsequent events

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U-Pb zircon-titanite-apatite age constraints on basin development and basin inversion in the Kiruna mining district, Sweden

Andersson

Logan

Martinsson

et al. 2022

Precambrian Research

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Scapolite: a tracer for the initial lead isotopic composition in sulfide deposits with later additions of radiogenic lead

Cited by 3 publications

References 14 publications

Cl/Br of scapolite as a fluid tracer in the earth's crust: insights into fluid sources in the Mary Kathleen Fold Belt, Mt. Isa Inlier, Australia

Cl/Br of scapolite as a fluid tracer in the earth's crust: insights into fluid sources in the Mary Kathleen Fold Belt, Mt. Isa Inlier, Australia

Metal source and tectonic setting of iron oxide-copper-gold (IOCG) deposits: Evidence from an in situ Nd isotope study of titanite from Norrbotten, Sweden

U-Pb zircon-titanite-apatite age constraints on basin development and basin inversion in the Kiruna mining district, Sweden

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