“The Lu–Hf isotope geochemistry of chondrites and the evolution of the mantle–crust system”

Blichert‐Toft, Janne; Albarède, Francis

doi:10.1016/s0012-821x(97)00198-2

Cited by 323 publications

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“…The operating conditions, detailed analytical procedure and data precision during Hf isotopic measurement were the same as those described in Griffin et al [30]. The ε Hf (t) values were calculated using the 176 Lu decay constant of 1.865×10 −11 a −1 suggested by Scherer et al [31], and Lu-Hf isotopic ratios of chondrite recommended by Blichert-toft and Albarede [32]. We also calculated the depleted-mantle model ages (T DM ) and average continental crust modal ages (T crust ) using 176 Lu/ 177 Hf of 0.015 [33] for the average continental crust and depleted mantle values proposed by Griffin et al [30].…”

Section: Methodsmentioning

confidence: 99%

Zircon U-Pb and Hf isotopes of volcanic rocks from the Batamayineishan Formation in the eastern Junggar Basin

Zheng

Griffin

et al. 2010

Chin. Sci. Bull.

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An internal structural study was conducted to investigate U-Pb age, trace elements and Hf isotopes of basaltic zircons from the Batamayineishan Formation. The basalt was obtained from drill well San-Can 1 on the eastern Luliang uplift within the Junggar Basin. Trace element data of zircons show that all samples are magmatic, with similar REE patterns, including positive Ce (δCe=5.06-134), but negative Eu (δEu=0.06-0.55) anomalies and enrichment in heavy rare earth elements. Among 25 grains, the concordant ages were subdivided into three groups; ages of 300.4±1.3 Ma (n=11), 339.2±2.7 Ma (n=3) and 392.0±1.7 Ma (n=8). Three remaining grains were nearly concordant, with 206 Pb/ 238 U ages of 510±7, 488±6 and 453±6 Ma, respectively. The youngest concordant age (i.e., 300.4±1.3 Ma) could be interpreted as the formation age of the studied basaltic rock; this is consistent with the sampling position at the upper part of the Batamayineishan Formation. On the other hand, ages such as Ordovician and early Devonian are consistent with the ages of island-arc volcanic rocks (enrichment in Pb) or ophiolites around the basin. Moreover, the positive ε Hf (t) values of the early and middle Paleozoic zircons (+3.6-+10.5) may suggest that the basement traversed by the studied volcanic rocks may be Paleozoic in age, formed from the residual oceanic crust and island-arc complex. The ε Hf (t) values (+4.2-+17.1) of the late Paleozoic (~300.4 Ma) zircons suggest that the basaltic magmas were derived from partial melting of the asthenospheric mantle or depleted lithospheric mantle. These magmas were slightly contaminated by the existence of early-middle Paleozoic materials. The late Carboniferous basalts represent direct eruption of mantle-derived magmas at the upper crustal level during a post-collisional tectonic setting. We therefore consider that extensive vertical growth of the continental crust to have occurred before the late Carboniferous. Batamayineishan Formation, zircon U-Pb ages, Hf isotopes, continental crust growth, eastern Junggar Basin Citation:Su Y P, Zheng J P, Griffin W L, et al. Zircon U-Pb and Hf isotopes of volcanic rocks from the Batamayineishan Formation in the eastern Junggar Basin.

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Section: Methodsmentioning

confidence: 99%

Zircon U-Pb and Hf isotopes of volcanic rocks from the Batamayineishan Formation in the eastern Junggar Basin

Zheng

Griffin

et al. 2010

Chin. Sci. Bull.

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“…Similarly, interference of 176 Yb on 176 Hf was corrected by measuring an interference-free 172 Yb isotope using a 176 Yb/ 172 Yb ratio of 0.5886 to calculate 176 Hf/ 177 Hf [23] . A decay constant for 176 Lu of 1.865× 10 −11 a −1 [24] and present-day chondritic ratios of 176 Hf/ 177 Hf = 0.282772 and 176 Lu/ 177 Hf = 0.0332 [25] were adopted to calculate ε Hf (t) values. Single-stage model ages (T DM1 ) were calculated by referring to depleted mantle with a present-day 176 Hf/ 177 Hf ratio of 0.28325 and 176 Lu/ 177 Hf ratio of 0.0384 [26] .…”

Section: Figurementioning

confidence: 99%

Paleoproterozoic reworking of ancient crust in the Cathaysia Block, South China: Evidence from zircon trace elements, U-Pb and Lu-Hf isotopes

et al. 2009

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“…176 Lu/ 177 Hf ratios of analysed zircons were not determined but 176 Lu/ 177 Hf ratios were corrected for a typical value of 176 Lu/ 177 Hf in zircon of 0.005; the correction stayed within limits of analytical precision of the measured 176 Hf/ 177 Hf ratios in all cases. The Hf isotopic ratios were corrected for mass fractionation using a 179 Hf/ 177 Hf value of 0.7325 and normalised to 176 Hf/ 177 Hf of 0.282160 of the JMC-475 standard (Blichert-Toft et al 1997). Errors of the mea- This sample contained a mixed zircon population.…”

Section: Hf Isotopesmentioning

confidence: 99%

Crustal-scale magmatic systems during intracontinental strike-slip tectonics: U, Pb and Hf isotopic constraints from Permian magmatic rocks of the Southern Alps

Schaltegger

Brack

2007

Int J Earth Sci (Geol Rundsch)

167

128

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The Southern Alps host volcano-sedimentary basins that formed during post-Variscan extension and strike-slip in the Early Permian. We present U-Pb ages and initial Hf isotopic compositions of magmatic zircons from silicic tuffs and pyroclastic flows within these basins, from caldera fillings and from shallow intrusions from a 250 km long E-W transect (Bozen- Lugano-Lago Maggiore) and compare these with previously published data. Basin formation and magmatism are closely related to each other and occurred during a short time span between 285 and 275 Ma. The silicic magmatism is coeval with mafic intrusions of the Ivrea-Verbano Zone and within Austroalpine units. We conclude that deep magma generation, hybridisation and upper crustal emplacement occurred contemporaneously along the entire transect of the Southern Alps. The heat advection in the lower crust by injected mantle melts was sufficient to produce crustal partial melts in lower crustal levels. The resulting granitoid melts intruded into the upper crust or rose to the surface forming large caldera complexes. The compilation of Sr and Nd isotopic data of these rocks demonstrates that the mantle mixing endmember in the melts may not be geochemically enriched but has a depleted composition, comparable to the Adriatic subcontinental mantle exhumed to form the Tethyan sea floor during Mesozoic continental breakup and seafloor spreading. Magmatism and clastic sedimentation in the intracontinental basins was interrupted at 275 Ma for some 10-15 million years, forming a Middle Permian unconformity. This unconformity may have originated during large-scale strike-slip tectonics and erosion that was associated with crustal thinning, upwelling and partial melting of mantle, and advection of melts and heat into the crust. The unconformity indeed corresponds in time to the transition from a Pangea-B plate reconstruction for the Early Permian to the Late Permian Pangea-A plate assembly (Muttoni et al. in Earth Planet Sci Lett 215:379-394, 2003). The magmatic activity would therefore indicate the onset of >2,000 km of strike-slip movement along a continental-scale mega-shear, as their model suggest

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“The Lu–Hf isotope geochemistry of chondrites and the evolution of the mantle–crust system”

Cited by 323 publications

References 0 publications

Zircon U-Pb and Hf isotopes of volcanic rocks from the Batamayineishan Formation in the eastern Junggar Basin

Zircon U-Pb and Hf isotopes of volcanic rocks from the Batamayineishan Formation in the eastern Junggar Basin

Paleoproterozoic reworking of ancient crust in the Cathaysia Block, South China: Evidence from zircon trace elements, U-Pb and Lu-Hf isotopes

Crustal-scale magmatic systems during intracontinental strike-slip tectonics: U, Pb and Hf isotopic constraints from Permian magmatic rocks of the Southern Alps

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