scholarly journals Meteorite zircon constraints on the bulk Lu−Hf isotope composition and early differentiation of the Earth

2015 ◽  
Vol 112 (17) ◽  
pp. 5331-5336 ◽  
Author(s):  
Tsuyoshi Iizuka ◽  
Takao Yamaguchi ◽  
Yuki Hibiya ◽  
Yuri Amelin
Keyword(s):  
Thermal Evolution ◽  
Isotope Composition ◽  
Isotope Analysis ◽  
Radioactive Decay ◽  
Data Interpretation ◽  
Hf Isotope ◽  
Accurate Estimation ◽  
The Earth ◽  
Planetary Differentiation ◽  
Firm Evidence

Knowledge of planetary differentiation is crucial for understanding the chemical and thermal evolution of terrestrial planets. The 176Lu−176Hf radioactive decay system has been widely used to constrain the timescales and mechanisms of silicate differentiation on Earth, but the data interpretation requires accurate estimation of Hf isotope evolution of the bulk Earth. Because both Lu and Hf are refractory lithophile elements, the isotope evolution can be potentially extrapolated from the present-day 176Hf/177Hf and 176Lu/177Hf in undifferentiated chondrite meteorites. However, these ratios in chondrites are highly variable due to the metamorphic redistribution of Lu and Hf, making it difficult to ascertain the correct reference values for the bulk Earth. In addition, it has been proposed that chondrites contain excess 176Hf due to the accelerated decay of 176Lu resulting from photoexcitation to a short-lived isomer. If so, the paradigm of a chondritic Earth would be invalid for the Lu−Hf system. Herein we report the first, to our knowledge, high-precision Lu−Hf isotope analysis of meteorite crystalline zircon, a mineral that is resistant to metamorphism and has low Lu/Hf. We use the meteorite zircon data to define the Solar System initial 176Hf/177Hf (0.279781 ± 0.000018) and further to identify pristine chondrites that contain no excess 176Hf and accurately represent the Lu−Hf system of the bulk Earth (176Hf/177Hf = 0.282793 ± 0.000011; 176Lu/177Hf = 0.0338 ± 0.0001). Our results provide firm evidence that the most primitive Hf in terrestrial zircon reflects the development of a chemically enriched silicate reservoir on Earth as far back as 4.5 billion years ago.

scholarly journals Sunda arc mantle source δ18O value revealed by intracrystal isotope analysis

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Frances M. Deegan ◽  
Martin J. Whitehouse ◽  
Valentin R. Troll ◽  
Harri Geiger ◽  
Heejin Jeon ◽  
...  
Keyword(s):  
Mantle Source ◽  
Secondary Ion Mass Spectrometry ◽  
Isotope Composition ◽  
Isotope Analysis ◽  
Sunda Arc ◽  
Mid Ocean Ridge ◽  
Plumbing Systems ◽  
Ocean Ridge ◽  
Secondary Ion ◽  
Magma Plumbing

AbstractMagma plumbing systems underlying subduction zone volcanoes extend from the mantle through the overlying crust and facilitate protracted fractional crystallisation, assimilation, and mixing, which frequently obscures a clear view of mantle source compositions. In order to see through this crustal noise, we present intracrystal Secondary Ion Mass Spectrometry (SIMS) δ18O values in clinopyroxene from Merapi, Kelut, Batur, and Agung volcanoes in the Sunda arc, Indonesia, under which the thickness of the crust decreases from ca. 30 km at Merapi to ≤20 km at Agung. Here we show that mean clinopyroxene δ18O values decrease concomitantly with crustal thickness and that lavas from Agung possess mantle-like He-Sr-Nd-Pb isotope ratios and clinopyroxene mean equilibrium melt δ18O values of 5.7 ‰ (±0.2 1 SD) indistinguishable from the δ18O range for Mid Ocean Ridge Basalt (MORB). The oxygen isotope composition of the mantle underlying the East Sunda Arc is therefore largely unaffected by subduction-driven metasomatism and may thus represent a sediment-poor arc end-member.

Compressibility of water in magma and the prediction of density crossovers in mantle differentiation

2008 ◽  
Vol 366 (1883) ◽  
pp. 4239-4252 ◽  
Author(s):  
Carl B Agee
Keyword(s):  
High Pressure ◽  
Compressible Liquid ◽  
Silicate Melt ◽  
Liquid Density ◽  
Low Velocity ◽  
Oxide Component ◽  
The Earth ◽  
Liquid Oxide ◽  
Planetary Differentiation ◽  
Pressure Regime

Hydrous silicate melts appear to have greater compressibility relative to anhydrous melts of the same composition at low pressures (<2 GPa); however, at higher pressures, this difference is greatly reduced and becomes very small at pressures above 5 GPa. This implies that the pressure effect on the partial molar volume of water in silicate melt is highly dependent on pressure regime. Thus, H 2 O can be thought of as the most compressible ‘liquid oxide’ component in silicate melt at low pressure, but at high pressure its compressibility resembles that of other liquid oxide components. A best-fit curve to the data on from various studies allows calculation of hydrous melt compression curves relevant to high-pressure planetary differentiation. From these compression curves, crystal–liquid density crossovers are predicted for the mantles of the Earth and Mars. For the Earth, trapped dense hydrous melts may reside atop the 410 km discontinuity, and, although not required to be hydrous, atop the core–mantle boundary (CMB), in accord with seismic observations of low-velocity zones in these regions. For Mars, a density crossover at the base of the upper mantle is predicted, which would produce a low-velocity zone at a depth of approximately 1200 km. If perovskite is stable at the base of the Martian mantle, then density crossovers or trapped dense hydrous melts are unlikely to reside there, and long-lived, melt-induced, low-velocity regions atop the CMB are not predicted.

Factors affecting 13C/12C ratios of inland halophytes. I. Controlled studies on growth and isotopic composition of Puccinellia nuttalliana

1986 ◽  
Vol 64 (11) ◽  
pp. 2693-2699 ◽  
Author(s):  
Robert D. Guy ◽  
David M. Reid ◽  
H. Roy Krouse
Keyword(s):  
Isotope Composition ◽  
Stable Carbon Isotope ◽  
Isotope Analysis ◽  
Research Problem ◽  
Carbon Isotope Composition ◽  
Stable Carbon ◽  
Factors Affecting ◽  
Plant Parts ◽  
High Level ◽  
Puccinellia Nuttalliana

Studies on various factors affecting the growth and stable carbon isotope composition of the graminaceous C3 halophyte Puccinellia nuttalliana (Schultes) Hitch. were initiated as a step towards interpreting δ13C variations in nature. For isotope analysis, combustion at 900 °C resulted in higher CO2 yield than at 550 °C but did not affect δ13C values. Differences in δ13C between leaves of different insertion level were unimportant, but roots were about 1‰ more positive than shoots. Trends in δ13C with salinity were the same in all plant parts. Depressions of growth by NaCl or Na2SO4 were similar, but plants grown in Na2SO4 displayed a greater shift in δ13C relative to controls. Growth rates were affected more by salinity than were previously reported photosynthetic rates. At typical salinities, δ13C changed linearly with salinity. The supply of nitrate to stressed and unstressed plants had no important influence on δ13C. Growth in polyethylene glycol produced δ13C values consistent with a high level of stress. After a salinity step-up, changes in δ13C were complete within 10 days. During winter, data were found to be heavily influenced by unintentional, human-respired CO2 enrichment. This represents a potentially serious research problem in laboratories of temperate climes.

Jurassic evolution of the Qaidam Basin in western China: Constrained by stratigraphic succession, detrital zircon U-Pb geochronology and Hf isotope analysis

2021 ◽  
Author(s):  
Tao Qian ◽  
Zongxiu Wang ◽  
Yu Wang ◽  
Shaofeng Liu ◽  
Wanli Gao ◽  
...  
Keyword(s):  
Late Jurassic ◽  
Qaidam Basin ◽  
Isotope Analysis ◽  
Lower Jurassic ◽  
Early Jurassic ◽  
Hf Isotope ◽  
Western China ◽  
Small Scale ◽  
Altyn Tagh ◽  
Stratigraphic Succession

The formation and evolution of an intracontinental basin triggered via the subduction or collision of plates at continental margins can record intracontinental tectonic processes. As a typical intracontinental basin during the Jurassic, the Qaidam Basin in western China records how this extensional basin formed and evolved in response to distant subduction or collisional processes and tectonism caused by stresses transmitted from distant convergent plate margins. The Jurassic evolution of the Qaidam Basin, in terms of basin-filling architecture, sediment dispersal pattern and basin properties, remains speculative; hence, these uncertainties need to be revisited. An integrated study of the stratigraphic succession, conglomerates, U-Pb geochronology, and Hf isotopes of detrital zircons was adopted to elucidate the Jurassic evolutionary process of the Qaidam Basin. The results show that a discrete Jurassic terrestrial succession characterized by alluvial fan, braided stream, braided river delta, and lacustrine deposits developed on the western and northern margins of the Qaidam Basin. The stratigraphic succession, U-Pb age dating, and Hf isotope analysis, along with the reconstructed provenance results, suggest small-scale distribution of Lower Jurassic sediments deposited via autochthonous sedimentation on the western margin of the basin, with material mainly originating from the Altyn Tagh Range. Lower Jurassic sediments in the western segment of the northern basin were shed from the Qilian Range (especially the South Qilian) and Eastern Kunlun Range. And coeval sediments in the eastern segment of the northern basin were originated from the Quanji massif. During the Middle-Late Jurassic, the primary source areas were the Qilian Range and Eastern Kunlun Range, which fed material to the whole basin. The Jurassic sedimentary environment in the Qaidam Basin evolved from a series of small-scale, scattered, and rift-related depressions distributed on the western and northern margins during the Early Jurassic to a larger, extensive, and unified depression occupying the whole basin in the Middle Jurassic. The Altyn Tagh Range rose to a certain extent during the Early Jurassic but lacked large-scale strike-slip tectonism throughout the Jurassic. At that time, the North Qaidam tectonic belt had not yet been uplifted and did not shed material into the basin during the Jurassic. The Qaidam Basin experienced intracontinental extensional tectonism with a northeast-southwest trend throughout the Jurassic in response to far-field effects driven by the sequential northward or northeastward amalgamation of blocks to the southern margin of the Qaidam Block and successive accretion of the Qiangtang Block and Lhasa Block onto the southern Eurasian margin during the Late Triassic−Early Jurassic and Late Jurassic−Early Cretaceous, respectively.

U–Pb and Hf-isotope analysis of zircons in mafic xenoliths from Fuxian kimberlites: evolution of the lower crust beneath the North China craton

2004 ◽  
Vol 148 (1) ◽  
pp. 79-103 ◽  
Author(s):  
Jianping Zheng ◽  
W. L. Griffin ◽  
Suzanne Y. O’Reilly ◽  
Fengxiang Lu ◽  
Chunmei Yu ◽  
...  
Keyword(s):  
North China Craton ◽  
Lower Crust ◽  
North China ◽  
Isotope Analysis ◽  
Hf Isotope ◽  
The North

Thermal evolution of the Earth

2014 ◽  
pp. 300-316 ◽  
Author(s):  
Claude Jaupart ◽  
Jean-Claude Mareschal
Keyword(s):  
Thermal Evolution ◽  
The Earth

Paleodietary Patterns of the Cherepakha 13 Site Population (Early Iron Age) in Primorye (Maritime) Province, Russian Far East, based on Stable Isotope Analysis

Radiocarbon ◽  
2018 ◽  
Vol 60 (5) ◽  
pp. 1611-1620 ◽  
Author(s):  
Yaroslav V Kuzmin ◽  
Vsevolod S Panov ◽  
Viacheslav V Gasilin ◽  
Sergei V Batarshev
Keyword(s):  
Stable Isotope ◽  
Iron Age ◽  
Isotope Composition ◽  
Russian Far East ◽  
Isotope Analysis ◽  
Far East ◽  
Bone Collagen ◽  
Early Iron Age ◽  
Terrestrial Mammals ◽  
Maritime Province

ABSTRACTNew paleodietary data were obtained after the discovery and excavation in 2015–2017 of the Cherepakha 13 site in the southern part of Primorye (Maritime) Province in far eastern Russia. The site is located near the coast of Ussuri Bay (Sea of Japan) and belongs to the Yankovsky cultural complex of the Early Iron Age 14C-dated to ca. 3000 BP (ca. 1200 cal BC). The stable isotope composition of the bone collagen for 11 humans and 30 animals was determined. For humans, the following values (with±1 sigma) were yielded: δ13C=–10.2±0.8‰; and δ15N=+12.4±0.3‰. The majority of terrestrial animals show the usual isotopic signals: δ13C=–19.4 ÷ –23.3‰; and δ15N=+4.6÷+6.6‰ (for wolves, up to +10.1‰); dogs, however, have an isotopic composition similar to humans: δ13C= –11.7±1.2‰; and δ15N=+12.4±0.4‰. Marine mammals have common values for pinnipeds: δ13C=–13.7 ÷ –14.6‰; and δ15N=+17.4 ÷ +18.0‰. The main food resources for the population of Cherepakha 13 site were (1) marine mollusks, fish, and mammals; and (2) terrestrial mammals; and possibly C4 plants (domesticated millets).

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