scholarly journals Noble Gas Isotope Composition of the Yellowstone Mantle Plume

2020 ◽  
Author(s):  
David J Byrne ◽  
Peter H Barry ◽  
Michael W Broadley ◽  
David V Bekaert ◽  
Matthieu Almayrac ◽  
...  
Keyword(s):  
Mantle Plume ◽  
Isotope Composition ◽  
Noble Gas ◽  
Noble Gas Isotope

scholarly journals The Petrogenesis of the Permian Podong Ultramafic Intrusion in the Tarim Craton, Western China: Constraints from C-He-Ne-Ar Isotopes

Geofluids ◽  
2019 ◽  
Vol 2019 ◽  
pp. 1-14 ◽  
Author(s):  
Mingjie Zhang ◽  
Pengyu Feng ◽  
Tong Li ◽  
Liwu Li ◽  
Juerong Fu ◽  
...  
Keyword(s):  
Oceanic Crust ◽  
Mantle Plume ◽  
Mantle Source ◽  
Noble Gas ◽  
Western China ◽  
Crustal Material ◽  
Sulfide Mineralization ◽  
Hydrocarbon Gases ◽  
Isotopic Compositions ◽  
Ultramafic Intrusion

The Podong Permian ultramafic intrusion is only one ultramafic intrusion with massif Ni-Cu sulfide mineralization in the Pobei layered mafic-ultramafic complex, western China. It is obviously different in sulfide mineralization from the nearby coeval Poyi ultramafic intrusion with the largest disseminated Ni-Cu sulfide mineralization and mantle plume contribution (Zhang et al., 2017). The type and addition mechanism of the confirmed crustal contaminations and possible mantle plume involved in the intrusion formation require evidences from carbon and noble gas isotopic compositions. In the present study, we have measured C, He, Ne, and Ar isotopic compositions of volatiles from magmatic minerals in the Podong ultramafic intrusion. The results show that olivine, pyroxene, and plagioclase minerals in the Podong intrusion have variable δ13C of CO2 (-24.5‰ to -3.2‰). The CH4, C2H6, C3H8, and C4H10 hydrocarbon gases show normal or partial reversal distribution patterns of carbon isotope with carbon number and light δ13C1 value of CH4, indicating the hydrocarbon gases of biogenic origin. The δ13C of CO2 and CH4 suggested the magmatic volatile of the mantle mixed with the volatiles of thermogenic and crustal origins. Carbon and noble gas isotopes indicated that the Podong intrusion could have a different petrogenesis from the Poyi ultramafic intrusion. Two types of contaminated crustal materials can be identified as crustal fluids from subducted altered oceanic crust (AOC) in the lithospheric mantle source and a part of the siliceous crust. The carbon isotopes for different minerals show that magma spent some time crystallizing in a magma chamber during which assimilation of crustal material occurred. Subduction-devolatilization of altered oceanic crust could be the best mechanism that transported large proportion of ASF (air-saturated fluid) and crustal components into the mantle source. The mantle plume existing beneath the Poyi intrusion could provide less contribution of real materials of silicate and fluid components.

Fluid inclusions, H-O, S, Pb, and noble gas isotope studies of the Baiyun gold deposit in the Qingchengzi orefield, NE China

2019 ◽  
Vol 200 ◽  
pp. 37-53 ◽  
Author(s):  
Peng Zhang ◽  
Lin-Lin Kou ◽  
Yan Zhao ◽  
Zhong-Wei Bi ◽  
De-Ming Sha ◽  
...  
Keyword(s):  
Gold Deposit ◽  
Fluid Inclusions ◽  
Noble Gas ◽  
Ne China ◽  
Noble Gas Isotope ◽  
Isotope Studies

scholarly journals Identification of chondritic krypton and xenon in Yellowstone gases and the timing of terrestrial volatile accretion

2020 ◽  
Vol 117 (25) ◽  
pp. 13997-14004 ◽  
Author(s):  
Michael W. Broadley ◽  
Peter H. Barry ◽  
David V. Bekaert ◽  
David J. Byrne ◽  
Antonio Caracausi ◽  
...  
Keyword(s):  
Mantle Plume ◽  
Noble Gases ◽  
Noble Gas ◽  
Mid Ocean Ridge ◽  
Mantle Sources ◽  
Source Mantle ◽  
Morb Source ◽  
Protosolar Nebula ◽  
Ocean Ridge ◽  
Yellowstone Caldera

Identifying the origin of noble gases in Earth’s mantle can provide crucial constraints on the source and timing of volatile (C, N, H2O, noble gases, etc.) delivery to Earth. It remains unclear whether the early Earth was able to directly capture and retain volatiles throughout accretion or whether it accreted anhydrously and subsequently acquired volatiles through later additions of chondritic material. Here, we report high-precision noble gas isotopic data from volcanic gases emanating from, in and around, the Yellowstone caldera (Wyoming, United States). We show that the He and Ne isotopic and elemental signatures of the Yellowstone gas requires an input from an undegassed mantle plume. Coupled with the distinct ratio of129Xe to primordial Xe isotopes in Yellowstone compared with mid-ocean ridge basalt (MORB) samples, this confirms that the deep plume and shallow MORB mantles have remained distinct from one another for the majority of Earth’s history. Krypton and xenon isotopes in the Yellowstone mantle plume are found to be chondritic in origin, similar to the MORB source mantle. This is in contrast with the origin of neon in the mantle, which exhibits an isotopic dichotomy between solar plume and chondritic MORB mantle sources. The co-occurrence of solar and chondritic noble gases in the deep mantle is thought to reflect the heterogeneous nature of Earth’s volatile accretion during the lifetime of the protosolar nebula. It notably implies that the Earth was able to retain its chondritic volatiles since its earliest stages of accretion, and not only through late additions.

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