scholarly journals Supplemental Material: Ordovician–Silurian back-arc silicic magmatism in the southernmost Appalachians

2022 ◽  
Author(s):  
Clinton I. Barineau ◽  
et al.
Keyword(s):  
Sample Preparation ◽  
Hf Isotope ◽  
Geochemical Analysis ◽  
Analysis Methodology ◽  
Correction Table ◽  
Major Oxide ◽  
Silicic Magmatism ◽  
Metaigneous Rocks ◽  
Back Arc ◽  
Isotope Analyses

Sample Preparation and Geochemical Analysis Methodology; Table S1: Major oxide percentages for metaigneous rocks of the Wedowee-Emuckfaw-Dahlonega basin; Table S2: Measured isotope ratios and normalized U-Pb ages calculated without 204Pb Correction; Table S3: Lu-Hf isotope analyses; Table S4: Latitude-longitude (WGS84), geologic unit, and age information for samples analyzed as part of this project.

scholarly journals Supplemental Material: Ordovician–Silurian back-arc silicic magmatism in the southernmost Appalachians

2021 ◽  
Author(s):  
Clinton I. Barineau ◽  
et al.
Keyword(s):  
Sample Preparation ◽  
Hf Isotope ◽  
Geochemical Analysis ◽  
Analysis Methodology ◽  
Correction Table ◽  
Major Oxide ◽  
Silicic Magmatism ◽  
Metaigneous Rocks ◽  
Back Arc ◽  
Isotope Analyses

Sample Preparation and Geochemical Analysis Methodology; Table S1: Major oxide percentages for metaigneous rocks of the Wedowee-Emuckfaw-Dahlonega basin; Table S2: Measured isotope ratios and normalized U-Pb ages calculated without 204Pb Correction; Table S3: Lu-Hf isotope analyses; Table S4: Latitude-longitude (WGS84), geologic unit, and age information for samples analyzed as part of this project.

scholarly journals Supplemental Material: Ordovician–Silurian back-arc silicic magmatism in the southernmost Appalachians

2021 ◽  
Author(s):  
Clinton I. Barineau ◽  
et al.
Keyword(s):  
Sample Preparation ◽  
Hf Isotope ◽  
Geochemical Analysis ◽  
Analysis Methodology ◽  
Correction Table ◽  
Major Oxide ◽  
Silicic Magmatism ◽  
Metaigneous Rocks ◽  
Back Arc ◽  
Isotope Analyses

Sample Preparation and Geochemical Analysis Methodology; Table S1: Major oxide percentages for metaigneous rocks of the Wedowee-Emuckfaw-Dahlonega basin; Table S2: Measured isotope ratios and normalized U-Pb ages calculated without 204Pb Correction; Table S3: Lu-Hf isotope analyses; Table S4: Latitude-longitude (WGS84), geologic unit, and age information for samples analyzed as part of this project.

scholarly journals Supplemental Material: Ordovician–Silurian back-arc silicic magmatism in the southernmost Appalachians

2021 ◽  
Author(s):  
Clinton I. Barineau ◽  
et al.
Keyword(s):  
Sample Preparation ◽  
Hf Isotope ◽  
Geochemical Analysis ◽  
Analysis Methodology ◽  
Correction Table ◽  
Major Oxide ◽  
Silicic Magmatism ◽  
Metaigneous Rocks ◽  
Back Arc ◽  
Isotope Analyses

Sample Preparation and Geochemical Analysis Methodology; Table S1: Major oxide percentages for metaigneous rocks of the Wedowee-Emuckfaw-Dahlonega basin; Table S2: Measured isotope ratios and normalized U-Pb ages calculated without 204Pb Correction; Table S3: Lu-Hf isotope analyses; Table S4: Latitude-longitude (WGS84), geologic unit, and age information for samples analyzed as part of this project.

scholarly journals Birth and demise of the Rheic Ocean magmatic arc(s): Combined U–Pb and Hf isotope analyses in detrital zircon from SW Iberia siliciclastic strata

Lithos ◽  
2017 ◽  
Vol 278-281 ◽  
pp. 383-399 ◽  
Author(s):  
M.F. Pereira ◽  
G. Gutíerrez-Alonso ◽  
J.B. Murphy ◽  
K. Drost ◽  
C. Gama ◽  
...  
Keyword(s):  
Detrital Zircon ◽  
Hf Isotope ◽  
Magmatic Arc ◽  
Rheic Ocean ◽  
Isotope Analyses

The Oman ophiolite as a Cretaceous arc-basin complex: evidence and implications

1981 ◽  
Vol 300 (1454) ◽  
pp. 299-317 ◽  
Keyword(s):  
Subduction Zone ◽  
Oceanic Crust ◽  
Significant Proportion ◽  
Dyke Swarm ◽  
Geochemical Analysis ◽  
Oman Ophiolite ◽  
Geochemical Evidence ◽  
Tectonic Development ◽  
High Level ◽  
Back Arc

Geological and geochemical evidence suggest that the Oman ophiolite is a fragment of a submarine arc-basin complex formed above a short-lived subduction zone in the mid-Cretaceous. Detailed studies of the lava stratigraphy and the intrusive relationships of dykes, sills and high-level plutons provide further evidence for the magmatic and tectonic development of the complex in question. Four consecutive events can be recognized to have taken place before emplacement: (1) eruption of basalts of island arc affinity onto pre-existing (Triassic) oceanic crust; (2) creation of new oceanic crust by backarc spreading; (3) intrusion of magma into this back-arc oceanic crust accompanied by eruption of basalts and andesites from discrete volcanic centres; (4) further intrusion of magma accompanied by uplift and eruption of basalts and rhyolites in submarine graben. A combined structural and geochemical analysis of the dyke swarm indicates that extension took place in approximately a N-S (ridge) and an ESE-WNW (leaky transform) direction relative to an inferred direction of subduction to the NE, and that a small but significant proportion of the sheeted dykes were injected during the ‘arc’ rather than the earlier ‘back-arc spreading’ episode. These various observations can be explained in terms of the progressive response of a non-isotropic lithosphere to the stresses induced during subduction.

scholarly journals Preferential dissolution of uranium-rich zircon can bias the hafnium isotope compositions of granites

Geology ◽  
2021 ◽  
Author(s):  
Peng Gao ◽  
Chris Yakymchuk ◽  
Jian Zhang ◽  
Changqing Yin ◽  
Jiahui Qian ◽  
...  
Keyword(s):  
Low Temperature ◽  
Trace Element ◽  
Partial Melting ◽  
Hf Isotope ◽  
Geochemical Data ◽  
Metasedimentary Rocks ◽  
Higher Temperature ◽  
Isotope Analyses ◽  
Preferential Dissolution ◽  
Temperature Melting

Hafnium (Hf) isotopes in zircon are important tracers of granite petrogenesis and continental crust evolution. However, zircon in granites generally shows large Hf isotope variations, and the reasons for this are debated. We applied U-Pb geochronology, trace-element, and Hf isotope analyses of zircon from the Miocene Himalayan granites to address this issue. Autocrystic zircon had εHf values (at 20 Ma) of –12.0 to –4.3 (median = –9). Inherited zircon yielded εHf values (at 20 Ma) of –34.8 to +0.3 (median = –13); the majority of εHf values were lower than those of autocrystic zircon. The εHf values of inherited zircon with high U concentrations resembled those of autocrystic zircon. Geochemical data indicates that the granites were generated during relatively low-temperature (<800 °C) partial melting of metasedimentary rocks, which, coupled with kinetic hindrance, may have led to the preferential dissolution of high-U zircon that could dissolve more efficiently into anatectic melt due to higher amounts of radiation damage. Consequently, Hf values of autocrystic zircon can be biased toward the values of U-rich zircon in the source. By contrast, literature data indicate that granites generated at high temperatures (<820–850 °C) generally contain autocrystic and inherited zircons with comparable Hf isotope values. During higher-temperature melting, indiscriminate dissolution of source zircon until saturation is reached will result in near-complete inheritance of Hf isotope ratios from the source. Our results impose an extra layer of complexity to interpretation of the zircon Hf isotope archive that is not currently considered.

scholarly journals Feldspar recycling across magma mush bodies during the voluminous Half Dome and Cathedral Peak stages of the Tuolumne intrusive complex, Yosemite National Park, California, USA

Geosphere ◽  
2021 ◽  
Author(s):  
Louis F. Oppenheim ◽  
Valbone Memeti ◽  
Calvin G. Barnes ◽  
Melissa Chambers ◽  
Joachim Krause ◽  
...  
Keyword(s):  
National Park ◽  
Earth Element ◽  
Geochemical Analysis ◽  
Intrusive Complex ◽  
Light Rare Earth ◽  
Magmatic System ◽  
Element Abundances ◽  
Anorthite Content ◽  
Incremental Growth ◽  
Major Oxide

Incremental pluton growth can produce sheeted complexes with no magma-magma interaction or large, dynamic magma bodies communicating via crystal and melt exchanges, depending on pulse size and frequency of intrusions. Determining the degree and spatial extent of crystal-melt exchange along and away from plutonic contacts at or near the emplacement level, such as in the large, long-lived Tuolumne intrusive complex (TIC) in California, sheds light onto the process and evolution of incremental growth. This study used field mapping and petrographic and geochemical analysis of plagioclase and K-feldspar populations in the equigranular Half Dome (eHD), porphyritic Half Dome (pHD), and Cathedral Peak (CP) Granodiorites of the southeastern section of the TIC to determine the presence and/or extent of feldspar recycling at interunit contacts. Our results suggest that contacts between major units are predominantly ~400-m- to 3-km-thick gradational zones. K-feldspar is compositionally distinct in eHD and neighboring gradational zones and shows no evidence of mixing. K-feldspar in a gradational zone between pHD and CP shows evidence of mixing between the two. Plagioclase in eHD and CP display distinct ranges of anorthite content, Sr, and light rare earth element abundances; both populations are observed in pHD. Major oxide and trace element calculations of melts in equilibrium with plagioclase cores indicate that the melts were more silicic, less calcic, and lower in Sr and Rb than corresponding analyzed whole-rock samples. These results suggest that the magmas also underwent plagioclase and biotite accumulation. The presence of two plagioclase populations in pHD is consistent with eHD and CP hybridizing to form pHD in an increasingly maturing and exchanging TIC magmatic system during the eHD-pHD-CP stages but before groundmass and small K-feldspar phenocrysts crystallized.

Sign in / Sign up

Export Citation Format

Share Document