The Galactic Evolution of Si, Ti, and O Isotopic Ratios

1999 ◽  
Vol 519 (1) ◽  
pp. 222-235 ◽  
Author(s):  
Conel M. O’D. Alexander ◽  
Larry R. Nittler
Keyword(s):  
Galactic Evolution ◽  
Isotopic Ratios

scholarly journals Silicon and Carbon Isotopic Ratios in AGB Stars: SiC Grain Data, Models, and the Galactic Evolution of the Si Isotopes

2006 ◽  
Vol 650 (1) ◽  
pp. 350-373 ◽  
Author(s):  
Ernst Zinner ◽  
Larry R. Nittler ◽  
Roberto Gallino ◽  
Amanda I. Karakas ◽  
Maria Lugaro ◽  
...  
Keyword(s):  
Data Models ◽  
Galactic Evolution ◽  
Isotopic Ratios ◽  
Agb Stars ◽  
Carbon Isotopic ◽  
Si Isotopes

Carbon and oxygen isotopes in AGB stars. From the cores of AGB stars to presolar dust

2018 ◽  
Vol 14 (S343) ◽  
pp. 447-448
Author(s):  
Thomas Lebzelter ◽  
Kenneth Hinkle ◽  
Oscar Straniero
Keyword(s):  
Solar System ◽  
Stellar Evolution ◽  
Galactic Evolution ◽  
Isotopic Ratios ◽  
Red Giants ◽  
Agb Stars ◽  
Carbon And Oxygen Isotopes ◽  
Different Types ◽  
Red Giant ◽  
Final Evolution

AbstractIsotopic ratios are a powerful tool for gaining insights into stellar evolution and nucleosynthesis. The isotopic ratios of the key elements carbon and oxygen are perfectly suited to investigate the pristine composition of red giants, the conditions in their interiors, and the mixing in their extended atmospheres. Of course the dust ejected from red giants in their final evolution also contains isotopically tagged material. This red giant dust is present in the solar system as presolar dust grains. We have measured isotopic ratios of carbon and oxygen in spectra from a large sample of AGB stars including both Miras and semiregular variables. We show how the derived ratios compare with expectations from stellar models and with measurements in presolar grains. Comparison of isotopes that are affected by different types of nucleosynthesis provides insights into galactic evolution.

Changes of Ionic and Oxygen Isotopic Composition of the Snowpack at the Glacier Austre Okstindbreen, Norway, 1995

1998 ◽  
Vol 29 (1) ◽  
pp. 1-20 ◽  
Author(s):  
Peter Raben ◽  
Wilfred H. Theakstone
Keyword(s):  
Isotopic Composition ◽  
Sea Level ◽  
Oxygen Isotopes ◽  
Oxygen Isotopic Composition ◽  
Isotopic Ratios ◽  
Vertical Variations ◽  
Oxygen Isotopic ◽  
The Difference ◽  
Liquid Precipitation ◽  
Different Altitudes

Marked vertical variations of ions and oxygen isotopes were present in the snowpack at the glacier Austre Okstindbreen during the pre-melting phase in 1995 at sites between 825 m and 1,470 m above sea level. As the first meltwater percolated from the top of the pack, ions were moved to a greater depth, but the isotopic composition remained relatively unchanged. Ions continued to move downwards through the pack during the melting phase, even when there was little surface melting and no addition of liquid precipitation. The at-a-depth correlation between ionic concentrations and isotopic ratios, strong in the pre-melting phase, weakened during melting. In August, concentrations of Na+ and Mg2+ ions in the residual pack were low and vertical variations were slight; 18O enrichment had occurred. The difference of the time at which melting of the snowpack starts at different altitudes influences the input of ions and isotopes to the underlying glacier.

Laramide to Miocene syn-extensional plutonism in the Puerta del Sol area, central Sonora, Mexico

2017 ◽  
Vol 34 (1) ◽  
pp. 45 ◽  
Author(s):  
Elizard González-Becuar ◽  
Efrén Pérez-Segura ◽  
Ricardo Vega-Granillo ◽  
Luigi Solari ◽  
Carlos Manuel González-León ◽  
...  
Keyword(s):  
Metamorphic Core Complex ◽  
Primitive Mantle ◽  
Isotopic Ratios ◽  
Magmatic Evolution ◽  
Calc Alkaline ◽  
Core Complex ◽  
High K ◽  
Sierra Madre ◽  
Plutonic Rocks ◽  
Metamorphic Core

Plutonic rocks of the Puerta del Sol area, in central Sonora, represent the extension to the south of the El Jaralito batholith, and are part of the footwall of the Sierra Mazatán metamorphic core complex, whose low-angle detachment fault bounds the outcrops of plutonic rocks to the west. Plutons in the area record the magmatic evolution of the Laramide arc and the Oligo-Miocene syn-extensional plutonism in Sonora. The basement of the area is composed by the ca. 1.68 Ga El Palofierral orthogneiss that is part of the Caborca block. The Laramide plutons include the El Gato diorite (71.29 ± 0.45 Ma, U-Pb), the El Pajarito granite (67.9 ± 0.43 Ma, U-Pb), and the Puerta del Sol granodiorite (49.1 ± 0.46 Ma, U-Pb). The younger El Oquimonis granite (41.78 ± 0.32 Ma, U-Pb) is considered part of the scarce magmatism that in Sonora records a transition to the Sierra Madre Occidental magmatic event. The syn-extensional plutons are the El Garambullo gabbro (19.83 ± 0.18 Ma, U-Pb) and the Las Mayitas granodiorite (19.2 ± 1.2 Ma, K-Ar). A migmatitic event that affected the El Palofierral orthogneiss, El Gato diorite, and El Pajarito granite between ca. 68 and 59 Ma might be related to the emplacement of the El Pajarito granite. The plutons are metaluminous to slightly peraluminous, with the exception of El Oquimonis granite, which is a peraluminous two-mica, garnet-bearing granite. They are mostly high-K calc-alkaline with nearly uniform chondrite-normalized REE and primitive-mantle normalized multielemental patterns that are characteristic of continental margin arcs and resemble patterns reported for other Laramide granites of Sonora. The Laramide and syn-extensional plutons also have Sr, Nd and Pb isotopic ratios that plot within the fields reported for Laramide granites emplaced in the Caborca terrane in northwestern and central Sonora. Nevertheless, and despite their geochemical affinity to continental magmatic arcs, the El Garambullo gabbro and Las Mayitas granodiorite are syn-extensional plutons that were emplaced at ca. 20 Ma during development of the Sierra Mazatán metamorphic core complex. The 40Ar/39Ar and K-Ar ages obtained for the El Palofierral orthogneiss, the Puerta del Sol granodiorite, the El Oquimonis granite, and the El Garambullo gabbro range from 26.3 ± 0.6 to 17.4 ± 1.0 Ma and are considered cooling ages associated with the exhumation of the metamorphic core complex.

Nitrogen isotopic ratios in Galactic AGB carbon stars

2013 ◽  
Author(s):  
Ruben Hedrosa ◽  
Carlos Abia ◽  
B. Plez ◽  
Inmaculada Domínguez
Keyword(s):  
Isotopic Ratios ◽  
Carbon Stars

NOVILLO METAMORPHIC COMPLEX, HUIZACHAL-PEREGRINA ANTICLINORIUM, TAMAULIPAS, MEXICO: CHARACTERIZATION AND DEVELOPMENT BASED ON WHOLE-ROCK GEOCHEMISTRY AND ND-ISOTOPIC RATIOS

2020 ◽  
Author(s):  
Eduardo Alejandro Alemán Gallardo ◽  
◽  
Juan Alonso Ramirez Fernandez ◽  
Bodo Weber ◽  
Uwe Jenchen ◽  
...  
Keyword(s):  
Isotopic Ratios ◽  
Metamorphic Complex
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