The anatectic effect on the zircon Hf isotope composition of migmatites and associated granites

Chen, Yixiang; Gao, Peng; Zheng, Yong‐Fei

doi:10.1016/j.lithos.2015.09.026

Cited by 46 publications

(17 citation statements)

References 77 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Zircon Hf isotope composition is widely used to trace the growth and evolution of continental crust (Belousova et al, ; Chen, Gao, & Zheng, ; Griffin, Belousova, Shee, Pearson, & O'Reilly, ; Xia, Zheng, & Chen, ). However, there is still debate regarding the Hf isotope composition of syn‐collisional granite magmatism from metamorphic processes and partial melting of subducted slabs.…”

Section: Discussionmentioning

confidence: 99%

“…However, there is still debate regarding the Hf isotope composition of syn‐collisional granite magmatism from metamorphic processes and partial melting of subducted slabs. Recent studies have revealed prominent Hf isotope variability in zircon from some migmatite and granite, especially S‐type granite (Chen et al, ; Farina, Stevens, Gerdes, & Frei, ; Flowerdew et al, ; Kemp et al, ; Maki et al, ; Tang et al, ). This raises questions about the mechanisms that result in such large Hf isotope variability and whether the Hf isotope composition for S‐type granite reflects the true source (Chen et al, ).…”

Section: Discussionmentioning

confidence: 99%

“…The lower 176 Hf/ 177 Hf(t) ratios imply that dissolution–reprecipitation of pre‐existing zircon is the main formation mechanism of the anatectic rims (Wu, Zheng, et al, ). In general, garnet has high 176 Lu/ 177 Hf ratios and thus formed extremely high 176 Hf/ 177 Hf(t) ratios after sufficient time for radiogenic Hf isotope ingrowth (Chen et al, ). The dissolution of garnet may cause an increase in zircon 176 Hf/ 177 Hf(t) ratios during the retrograde stage (Figure c).…”

Section: Discussionmentioning

confidence: 99%

“…The different 176 Hf/ 177 Hf(t), ε Hf (t), and 176 Lu/ 177 Hf ratios among the prograde and retrograde trends (Figure a–c) imply that the formation and consumption of minerals will affect Hf isotopic composition variability, even in a closed system. The elevated 176 Hf/ 177 Hf(t) ratios for newly grown zircon domains in the migmatites cannot reflect the Hf isotope compositions of their source rock (Chen et al, ).…”

Section: Discussionmentioning

confidence: 99%

“…In a broad sense, S‐type granite forms from repeated intracrustal differentiation by metasediment partial melting, which is similar to anatectic melts with complete separation from the parental rock (Zheng & Hermann, ). Zircon crystallized from the melts may not yield reasonable Lu–Hf ages due to the effect of Hf‐bearing minerals and garnet in the complex separation process (Chen et al, ; Farina et al, ; Tang et al, ).…”

Section: Discussionmentioning

confidence: 99%

See 4 more Smart Citations

Tracking the timing and nature of protolith, metamorphism, and partial melting of tourmaline‐bearing migmatites by zircon U–Pb and Hf isotopic compositions in the Yuka terrane, North Qaidam UHP metamorphic belt

Gao

Chen

et al. 2018

Geological Journal

View full text Add to dashboard Cite

An integrated study using cathodoluminescence (CL) images, U–Pb geochronology, and Hf isotopic characterization of zircons was performed on migmatites from the Yuka terrane to provide insights into the timing and nature of the protoliths, metamorphism, and partial melting of these rocks. Zircon grains separated from the migmatites have three distinct domains. Residual zircon cores in samples YKT01 and YKT02 exhibit oscillatory zoning, high Th/U ratios (0.10–0.79), steep heavy rare earth element (HREE) patterns, and mean ages of 936 ± 5 Ma and 927 ± 11 Ma, respectively, indicating that they are igneous in origin and record Neoproterozoic magmatism during the Grenvillian Orogeny. CL‐grey cores record an ultrahigh‐pressure (UHP) peak metamorphism age of 435 ± 5 Ma and have low Th/U and 176Lu/177Hf ratios, weak negative Eu anomalies, and relatively flat HREE patterns. The CL‐bright rims have steep HREE patterns with lower middle rare earth element (MREE) concentrations but higher HREE concentrations compared with the metamorphic cores and a weighted average age of 422 ± 4 Ma, which records the timing of melt crystallization. The migmatites incorporate garnet relicts coexisting with fluid inclusions and hydrous minerals like peritectic phengite and peritectic large anhedral poikilitic tourmaline in the leucosomes. Peak temperatures are less than 750°C, suggesting that the anatectic melts may be derived from melting of felsic gneiss in the presence of water. The timing of melt crystallization is ca. 13 Ma later than UHP metamorphism, indicating that the partial melting took place during the exhumation stage. The metamorphic zircon cores have higher 176Hf/177Hf(t) ratios than the residual magmatic cores, which provides powerful evidence for the generation of the metamorphic zircons through the incorporation of internal high Hf minerals other than zircon in a closed system. Anatectic rims with lower 176Hf/177Hf(t) ratios but higher 176Lu/177Hf ratios than metamorphic cores suggest that the main formation mechanism is dissolution‐reprecipitation of pre‐existing zircons. In conclusion, the elevated 176Hf/177Hf(t), TDM2 age and decreasing 176Lu/177Hf(t) ratios in the metamorphic and anatectic domains imply that the new zircons in some migmatites and granites may not reflect the Hf isotope compositions of their source rocks, accounting for the variable Hf isotope compositions in S‐type granites.

show abstract

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

See 3 more Smart Citations

Tracking the timing and nature of protolith, metamorphism, and partial melting of tourmaline‐bearing migmatites by zircon U–Pb and Hf isotopic compositions in the Yuka terrane, North Qaidam UHP metamorphic belt

Gao

Chen

et al. 2018

Geological Journal

View full text Add to dashboard Cite

show abstract

Mesozoic multi‐stage W–Sn polymetallic mineralization in the Nanling Range, South China: An example from the Dengfuxian–Xitian ore field

Sun

Algeo

et al. 2018

Geological Journal

View full text Add to dashboard Cite

The Dengfuxian and Xitian ore fields, located in the central Nanling Range of South China, are characterized by multi‐stage W–Sn polymetallic mineralization. In this study, whole‐rock and zircon compositions in altered granites from four typical deposits in these ore fields (i.e., Dalong Pb–Zn, Xiangdong W, Gaolong fluorite, and Shaiheling Sn–Pb–Zn) were studied to constrain their fluid chemistry and mineralization history. Compared to unaltered granites at Dengfuxian and Xitian, these fluid‐altered granites are characterized by more variable SiO2 (64.2–78.4%) and lower TiO2 (0.02–0.12%), CaO (0.25–1.2%), and Na2O (0.31–2.6%) concentrations, lower ΣREE (87–156 ppm), and higher Zr/Hf (11.1–31.6) and Y/Ho (31.1–53.4) ratios, suggesting intense F‐rich fluid metasomatism. Zircon cathodoluminescence (CL), transmitted light and back‐scattered electron (BSE) imaging, laser ablation multi‐collector inductively coupled plasma mass spectrometry (LA‐MC‐ICP‐MS) trace‐element analysis, U–Pb dating, and Hf isotopes revealed a sequence of three W–Sn polymetallic mineralization stages: a Triassic stage (~220 Ma), a Jurassic stage (~150 Ma), and a Cretaceous stage (~80 Ma). The Triassic episode was associated with a highly fractionated granitic magma derived from the lower crust and contaminated by basement rocks; the magmatic fluid was affected by a high 176Hf/177Hf component from the ~770‐Ma basement and probably precipitated under high F and high fO2 conditions. The Jurassic episode was related to mantle–crust interaction and resulted in large‐scale W–Sn mineralization at decreased fO2. The Cretaceous episode was marked by Sn mineralization in a lithospheric extensional setting. We infer that basement rocks were the major source of metals for the world‐class W–Sn ore deposits in the Nanling Range of South China. This study also demonstrates that whole‐rock geochemistry of hydrothermally altered granites in combination with Lu–Hf isotopic, U–Pb dating, and trace element analyses of magmatic and hydrothermal zircons can be a useful approach to recognition of multi‐stage magmatic and mineralization processes.

show abstract

Petrological, geochemical, isotopic, and geochronological constraints for the Late Devonian–Early Carboniferous magmatism in SW Gondwana (27–32°LS): an example of geodynamic switching

Dahlquist

Alasino

Basei

et al. 2018

Int J Earth Sci (Geol Rundsch)

View full text Add to dashboard Cite

The anatectic effect on the zircon Hf isotope composition of migmatites and associated granites

Cited by 46 publications

References 77 publications

Tracking the timing and nature of protolith, metamorphism, and partial melting of tourmaline‐bearing migmatites by zircon U–Pb and Hf isotopic compositions in the Yuka terrane, North Qaidam UHP metamorphic belt

Tracking the timing and nature of protolith, metamorphism, and partial melting of tourmaline‐bearing migmatites by zircon U–Pb and Hf isotopic compositions in the Yuka terrane, North Qaidam UHP metamorphic belt

Mesozoic multi‐stage W–Sn polymetallic mineralization in the Nanling Range, South China: An example from the Dengfuxian–Xitian ore field

Petrological, geochemical, isotopic, and geochronological constraints for the Late Devonian–Early Carboniferous magmatism in SW Gondwana (27–32°LS): an example of geodynamic switching

Contact Info

Product

Resources

About