Thursday, August 21, 2014

 

 



Soy un nuevo usuario

Olvidé mi contraseña

Entrada usuarios

Lógica Matemáticas Astronomía y Astrofísica Física Química Ciencias de la Vida
Ciencias de la Tierra y Espacio Ciencias Agrarias Ciencias Médicas Ciencias Tecnológicas Antropología Demografía
Ciencias Económicas Geografía Historia Ciencias Jurídicas y Derecho Lingüística Pedagogía
Ciencia Política Psicología Artes y Letras Sociología Ética Filosofía


Cosmogenic ^3He and ^(21)Ne dating of biotite and hornblende

1) La descarga del recurso depende de la página de origen
2) Para poder descargar el recurso, es necesario ser usuario
    registrado en Universia

  Descargar recurso

Detalles del recurso

Pertenece a: Caltech Authors  

Descripción: Stable cosmogenic isotopes such as ^3He and ^(21)Ne are useful for dating of diverse lithologies, quantifying erosion rates and ages of ancient surfaces and sediments, and for assessing complex burial histories. Although many minerals are potentially suitable targets for ^3He and ^(21)Ne dating, complex production systematics require calibration of each mineral–isotope pair. We present new results from a drill core in a high-elevation ignimbrite surface, which demonstrates that cosmogenic ^3He and ^(21)Ne can be readily measured in biotite and hornblende. ^(21)Ne production rates in hornblende and biotite are similar, and are higher than that in quartz due to production from light elements such as Mg and Al. We measure ^(21)Ne_(hbl)/^(21)Ne_(qtz) = 1.35 ± 0.03 and ^(21)Ne_(bio)/^(21)Ne_(qtz) = 1.3 ± 0.02, which yield production rates of 25.6 ± 3.0 and 24.7 ± 2.9 at g^(−1) yr^(−1) relative to a ^(21)Ne_(qtz) production rate of 19.0 ± 1.8 at g^(−1) yr^(−1). We show that nucleogenic ^(21)Ne concentrations produced via the reaction ^(18)O(α,n)^(21)Ne are manageably small in this setting, and we present a new approach to deconvolve nucleogenic ^(21)Ne by comparison to nucleogenic ^(22)Ne produced from the reaction ^(19)F(α,n)^(22)Ne in F-rich phases such as biotite. Our results show that hornblende is a suitable target phase for cosmogenic ^3He dating, but that ^3He is lost from biotite at Earth surface temperatures. Comparison of ^3He concentrations in hornblende with previously measured mineral phases such as apatite and zircon provides unambiguous evidence for ^3He production via the reaction ^6Li(n,α)^3H → ^3He. Due to the atypically high Li content in the hornblende (~ 160 ppm) we estimate that Li-produced ^3He represents ~ 40% of total ^3He production in our samples, and must be considered on a sample-specific basis if 3He dating in hornblende is to be widely implemented.

Autor(es): Amidon, William H. -  Farley, Kenneth A. - 

Id.: 55202810

Versión: 1.0

Estado: Final

Tipo de recurso: Article  -  PeerReviewed  - 

Tipo de Interactividad: Expositivo

Nivel de Interactividad: muy bajo

Audiencia: Estudiante  -  Profesor  -  Autor  - 

Estructura: Atomic

Coste: no

Copyright: sí

Requerimientos técnicos:  Browser: Any - 

Relación: [References] http://resolver.caltech.edu/CaltechAUTHORS:20120416-090156503
[References] http://authors.library.caltech.edu/30094/

Fecha de contribución: 17-abr-2012

Contacto:

Localización:


Otros recursos del mismo autor(es)

  1. Non-Detection of Methane in the Mars Atmosphere by the Curiosity Rover By analogy with Earth, methane in the atmosphere of Mars is a potential signature of ongoing or past...
  2. Progressive glacial retreat in the Southern Altiplano (Uturuncu volcano, 22°S) between 65 and 14 ka constrained by cosmogenic ^3He dating This work presents the first reconstruction of late Pleistocene glacier fluctuations on Uturuncu vol...
  3. Amphitheater-headed canyons formed by megaflooding at Malad Gorge, Idaho The shapes of bedrock canyons offer clues to the history of surface water on Earth and Mars. Using f...
  4. Supplementary material: XRF core scanning data, CaCO3 values, foraminiferal carbon and oxygen isotope data, Mg/Ca data, clay mineralogy and helium isotope results The Paleocene-Eocene Thermal Maximum (PETM; ~56 Ma) is associated with abrupt climate change, carbon...
  5. Supplementary table 3: Helium isotope data of DSDP Site 48-401

Otros recursos de la misma colección

  1. Changes of lead and barium with time in California off-shore basin sediments During ancient times the natural deposition fluxes of lead which can be leached with dilute acid fro...
  2. Laboratory Studies on the Reactions between Chlorine, Sulfur Dioxide, and Oxygen: Implications for the Venus Stratosphere The title reaction was studied by photolyzing mixtures of Cl_2 and SO_2 with and without O_2 present...
  3. Photochemistry of the Stratosphere of Venus: Implications for Atmospheric Evolution The photochemistry of the stratosphere of Venus was modeled using an updated and expanded chemical s...
  4. A Note on the Variational Method of Stokes and DeMarcus for Radiative Transfer in Planetary Atmospheres A generalized functional which yields the Milne integral equation on variation and whose extremum va...
  5. A model for the shape of the Fourier amplitude spectrum of acceleration at high frequencies At high frequencies f the spectrum of S-wave accelerations is characterized by a trend of exponentia...

Valoración de los usuarios

No hay ninguna valoración para este recurso.Sea el primero en valorar este recurso.
 

Busque un recurso