Video Experimental Relacionado
Updated: Jul 14, 2026
06:04
Simulation of the Planetary Interior Differentiation Processes in the Laboratory
Published on: November 16, 2013
Evolución de los isótopos de helio en el manto terrestre
Cornelia Class1, Steven L Goldstein
1Lamont-Doherty Earth Observatory of Columbia University, Palisades, New York 10964, USA class@ldeo.columbia.edu
Nature
|August 27, 2005
Resumen
Las altas proporciones de helio-3 a helio-4 en los basaltos de las islas oceánicas sugieren una desgasificación incompleta del manto terrestre, no un depósito primordial. Este hallazgo reconcilia las contradicciones de larga data en la dinámica del manto.
Área de la Ciencia:
- La geoquímica es la geoquímica.
- La geofísica es la geofísica.
- Geología de Isótopos Geología de Isótopos.
Sus antecedentes:
- La desgasificación del manto de la Tierra a través del magmatismo conduce a la pérdida de helio al espacio.
- Las altas proporciones de (3) He/(4) He en los basaltos oceánicos se consideran tradicionalmente como evidencia de un depósito de manto profundo sin gas.
Objetivo del estudio:
- Para investigar el origen de las altas proporciones de (3) He/(4) He en basaltos de islas oceánicas.
- Desafiar la necesidad de un reservorio primordial y sin gas en el manto profundo.
Principales métodos:
- Compilación de datos globales de basalto de las islas oceánicas.
- Comparación de las firmas químicas e isotópicas de los basaltos de las islas oceánicas y de los basaltos de la cordillera oceánica media.
Principales resultados:
- Los basaltos de las islas oceánicas con las proporciones más altas de (3) He/(4) He muestran similitudes con los basaltos de la cordillera oceánica media.
- Estas similitudes sugieren una historia compartida de agotamiento de oligoelementos a través del magmatismo.
- El alto contenido de (3) He/(4) He en las columnas puede ser el resultado de una desgasificación incompleta del manto durante la formación de la corteza.
Conclusiones:
- No se requiere un reservorio de manto profundo primordial y sin gas para explicar las altas proporciones de (3) He/(4) He.
- Las diferencias entre las fuentes de pluma y el manto superior indican un aislamiento de 1 a 2 mil millones de años.
- Esto reconcilia las observaciones con los modelos de la dinámica del manto.
Más Videos Relacionados
Videos de Conceptos Relacionados
01:12Isotopes
Elements have a set number of protons that determines their atomic number (Z). For example, all atoms with eight protons are oxygen; however, the number of neutrons can vary for atoms of the same element. The sum of the number of protons and the number of neutrons is the mass number (A). Atoms with the same atomic number but different mass numbers are called isotopes. Elements can have multiple isotopes, for example, carbon-12, carbon-13, and carbon-14.An element's atomic mass, or weight, is a...
02:54Noble Gases
The elements in group 18 are noble gases (helium, neon, argon, krypton, xenon, and radon). They earned the name “noble” because they were assumed to be nonreactive since they have filled valence shells. In 1962, Dr. Neil Bartlett at the University of British Columbia proved this assumption to be false.
03:18Nuclear Stability
Protons and neutrons, collectively called nucleons, are packed together tightly in a nucleus. With a radius of about 10−15 meters, a nucleus is quite small compared to the radius of the entire atom, which is about 10−10 meters. Nuclei are extremely dense compared to bulk matter, averaging 1.8 × 1014 grams per cubic centimeter. If the earth’s density were equal to the average nuclear density, the earth’s radius would be only about 200 meters.
To hold positively charged protons together in the...
To hold positively charged protons together in the...
02:13Nuclear Binding Energy
The difference between the calculated and experimentally measured masses is known as the mass defect of the atom. In the case of helium-4, the mass defect indicates a “loss” in mass of 4.0331 amu – 4.0026 amu = 0.0305 amu. The loss in mass accompanying the formation of an atom from protons, neutrons, and electrons is due to the conversion of that mass into energy that is evolved as the atom forms. The nuclear binding energy is the energy produced when the atoms’ nucleons are bound together;...
02:45Nuclear Fusion
The process of converting very light nuclei into heavier nuclei is also accompanied by the conversion of mass into large amounts of energy, a process called fusion. The principal source of energy in the sun is a net fusion reaction in which four hydrogen nuclei fuse and ultimately produce one helium nucleus and two positrons.
A helium nucleus has a mass that is 0.7% less than that of four hydrogen nuclei; this lost mass is converted into energy during the fusion. This reaction produces about...
A helium nucleus has a mass that is 0.7% less than that of four hydrogen nuclei; this lost mass is converted into energy during the fusion. This reaction produces about...
01:13Mass Spectrometry: Isotope Effect
Most elements exist in nature as a mixture of isotopes. The isotopes differ in weight due to their respective number of neutrons. The molecular weight of a molecule is different depending on the specific isotope of its elements involved. As a result, the mass spectrum of the molecule exhibits peaks from the same fragment at multiple positions. The positions of these mass signals depend on the mass differences between isotopes. Furthermore, the intensity of these signals is dependent on the...