Contrasting Sr and Nd isotopic behaviour during magma mingling; new insights from the Mannum A-type granite

Pankhurst, Matthew J.; Vernon, R. H.; Turner, Simon; Schaefer, Bruce F.; Foden, John

doi:10.1016/j.lithos.2011.07.005

Cited by 30 publications

(11 citation statements)

References 35 publications

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“…The Nd and Sr isotope compositions were determined by thermal ionization mass spectrometry at the University of Adelaide (Australia) following the same protocol as Pankhurst et al (2011). The analytical data are given in Table DR4.…”

Section: Geochemistrymentioning

confidence: 99%

Are granites and granulites consanguineous?

Korhonen

Brown

Clark

et al. 2015

Geology

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An important question in petrology is whether the production of granite magma in orogens is a closed-system process with respect to mass input from the mantle. This is commonly addressed by inversion of geochemical data from upper crustal granites, but a complementary approach is to assess the kinship of residual granulites and associated granites in exhumed orogenic crust. Here we report geochemical data for a suite of contemporaneous metasedimentary granulites and granites from the Eastern Ghats Province, India, part of a Grenville-age orogen. The prograde metamorphic evolution involved increasing temperature (T) and pressure (P) to a metamorphic peak at >1000 °C at ~0.7 GPa, followed by slow close-to-isobaric cooling. Variations in the composition of granites are interpreted to be due to local processes, including fractionation during melting or crystallization, and/or peritectic mineral entrainment. The Nd and Sr isotope compositions of the granites can be matched by mixing between different granulites, suggesting that they may have been derived solely from sedimentary protoliths leaving behind granulite facies residues. However, by including geochemical data from an adjacent area to the north, it becomes clear that an increasingly important mass input from the mantle was involved in granite genesis from southwest to northeast in the Eastern Ghats Province, as confirmed by modeling assimilation-fractional crystallization between an exemplar mantle-derived melt at 1000 Ma and the residual granulites. The extreme peak metamorphic temperature and P-T evolution suggest extended lithosphere that relaxed thermally to its former thickness during slow cooling. We postulate that the spatial variation in mantle input to the granites was related to changing feedback between the rates of extension and flux of mantle melt.

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Section: Geochemistrymentioning

confidence: 99%

Are granites and granulites consanguineous?

Korhonen

Brown

Clark

et al. 2015

Geology

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“…This causes additional complexities to the interpretation of whole-rock isotope ratios. Pankhurst et al (2011c) The resulting magmas (containing isotopically distinct titanite crystals) were readily mixed due to similar viscosities. A similar process produced granites containing chemically similar yet isotopically dissimilar titanite crystals, which also mixed readily.…”

Section: Hf Isotope Constraintsmentioning

confidence: 99%

“…Both these systems reflect lithophile behaviour, but potentially may misrepresent a suspected mantle component, due to inheritance via magma assimilation or mingling (e.g. Pankhurst et al, 2011c). The Lu-Hf system broadly approximates the Sm-Nd, however due to the relative difference in D values, the Lu-Hf system is less affected by AFC processes (following the models of DePaolo, 1981).…”

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confidence: 99%

The source of A-type magmas in two contrasting settings: U–Pb, Lu–Hf and Re–Os isotopic constraints

et al. 2013

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“…Many compositional variations have been found for A‐type granites, and there is no consensus on their origin (Bonin, ). A‐type granites are genetically diverse and can be produced from various sources and by different processes; thus, several origin models have been proposed, including (a) fractional crystallization of mantle‐derived melts (Anderson, Frost, & Frost, ; Jiang, Zhang, Zhou, & Liu, ; Mansouri Esfahani, Khalili, Kochhar, & Gupta, ; Namur et al, ), (b) partial melting of crustal rocks (Clemens, Holloway, & White, ; Dall'Agnol, Scaillet, & Pichavant, ; Whalen et al, ), and (c) hybridization between anatectic crustal and mantle‐derived magmas (Jung, Mezger, & Hoernes, ; Karsli et al, ; Pankhurst, Vernon, Turner, Schaefer, & Foden, ; Trumbull, Harris, Frindt, & Wigand, ; Yang, Wu, Chung, Wilde, & Chu, ).…”

Section: Discussionmentioning

confidence: 99%

Petrogenesis and tectonic setting of the Middle Permian A‐type granites in Altay, northwestern China: Evidences from geochronological, geochemical, and Hf isotopic studies

et al. 2017

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The Jiangjunshan and Dakalasu alkali‐feldspar granites are located in the central part of the Chinese Altay orogen. In this paper, we present detailed geochemical, zircon U–Pb, and Hf isotopic data of these granites. The Jiangjunshan and Dakalasu alkali‐feldspar granites show a high content of SiO2 (72.05–73.27 and 69.55–71.04 wt%, respectively), total alkalis (Na2O + K2O = 8.41–8.71 and 7.24–8.66 wt%, respectively), and high‐field strength elements (Zr + Nb + Ce + Y = 400.3–482.9 and 156.7–339.3 ppm, respectively), as well as high Ga/Al ratios (10,000 × Ga/Al = 3.46–4.19 and 2.62–3.28, respectively) and depletion in Ba, Nb, Sr, and Ti, showing geochemical characteristics similar to those of A‐type granites. Zircon U–Pb dating of the Jiangjunshan and Dakalasu alkali‐feldspar granites yielded weighted mean dating 206Pb/238U ages of 268.3 ± 1.9 and 270.4 ± 1.9 Ma, respectively, indicating that these granites intruded during the Permian. The Jiangjunshan and Dakalasu alkali‐feldspar granites show highly variable zircon εHf(t) values ranging from −7.0 to +5.6, implying that these granites originated from a mixing of mantle‐derived magma with crustal materials. Our data on the Jiangjunshan and Dakalasu alkali‐feldspar granites, coupled with previous studies of Permian magmatism and metamorphism, suggest that the tectonic regime was in a postcollisional extensional environment in the Chinese Altay orogen during the Permian. Therefore, the change in stress from compression to extension and asthenospheric upwelling triggered by slab break‐off plays a significant role in the generation of Jiangjunshan and Dakalasu alkali‐feldspar granites.

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Contrasting Sr and Nd isotopic behaviour during magma mingling; new insights from the Mannum A-type granite

Cited by 30 publications

References 35 publications

Are granites and granulites consanguineous?

Are granites and granulites consanguineous?

The source of A-type magmas in two contrasting settings: U–Pb, Lu–Hf and Re–Os isotopic constraints

Petrogenesis and tectonic setting of the Middle Permian A‐type granites in Altay, northwestern China: Evidences from geochronological, geochemical, and Hf isotopic studies

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