Video Experimental Relacionado
Updated: May 23, 2026
08:43
Separation of Uranium and Thorium for 230Th-U Dating of Submarine Hydrothermal Sulfides
Published on: May 20, 2019
238U/235U Sistemática en los minerales terrestres que contienen uranio
Joe Hiess1, Daniel J Condon, Noah McLean
1NERC Isotope Geoscience Laboratory, British Geological Survey, Keyworth, Nottinghamshire, UK. jies@bgs.ac.uk
Science (New York, N.Y.)
|March 31, 2012
Resumen
La relación uranio-238 / uranio-235 no es constante, lo que desafía su uso en la datación de minerales. Nuevas mediciones revelan variaciones, impactando la geocronología de uranio-plomo y nuestra comprensión de la composición de la Tierra.
Área de la Ciencia:
- La geoquímica es la geoquímica.
- Geología de Isótopos Geología de Isótopos.
- Las citas radiométricas.
Sus antecedentes:
- La relación actual de uranio 238/uranio 235 es crucial para la geocronología y la cosmocronología del uranio-plomo.
- Una relación invariante previamente asumida de 137,88 se ha utilizado sin incertidumbre para calcular las edades de los minerales terrestres.
Objetivo del estudio:
- Investigar la variabilidad de la relación actual de uranio 238/uranio 235 en los minerales terrestres.
- Evaluar las implicaciones de esta variabilidad para la geocronología y la cosmocronología del uranio-plomo.
Principales métodos:
- Se realizaron mediciones de alta precisión de la relación Uranio-238 / Uranio-235 en minerales que contienen uranio de 58 muestras litológicas diversas.
- El análisis incluyó una gama de tipos de minerales para capturar las variaciones isotópicas.
Principales resultados:
- Se observó un rango significativo de más de 5 por mil en los valores de Uranio-238/Uranio-235 en las muestras.
- No se encontró una correlación clara con tendencias petrogenéticas, seculares o regionales, lo que sugiere una fraccionamiento localizado.
- Las variaciones entre los minerales comagmáticos indican que la fraccionamiento del uranio 238/uranio 235 ocurre a temperaturas magmáticas.
Conclusiones:
- La relación Uranio 238/Uranio 235 es demostrablemente variable, lo que requiere ajustes en los cálculos geocronológicos.
- Un valor medio de Uranio-238/Uranio-235 de 137.818 ± 0.045 (2σ) en circones representa la composición isotópica y la variabilidad del circón terrestre.
- Esta distribución observada es ampliamente representativa de las composiciones promedio de Uranio-238 / Uranio-235 de la corteza terrestre y la Tierra a granel.
Más Videos Relacionados
12:05U2O5 Film Preparation via UO2 Deposition by Direct Current Sputtering and Successive Oxidation and Reduction with Atomic Oxygen and Atomic Hydrogen
Published on: February 21, 2019
07:52A Novel Technique for Raman Analysis of Highly Radioactive Samples Using Any Standard Micro-Raman Spectrometer
Published on: April 12, 2017
Videos de Conceptos Relacionados
01:25Microbial Bioremediation of Uranium
Microorganisms play a critical role in the transformation and immobilization of uranium in contaminated environments through four main pathways: bioreduction, biosorption, bioaccumulation, and biomineralization. These mechanisms reduce uranium’s toxicity and prevent its migration through groundwater systems, offering sustainable approaches for in situ bioremediation.Bioreduction of UraniumBioreduction is driven by anaerobic bacteria such as certain strains of Geobacter and Shewanella, which use...
03:20Nuclear Transmutation
Nuclear transmutation is the conversion of one nuclide into another. It can occur by the radioactive decay of a nucleus, or the reaction of a nucleus with another particle. The first manmade nucleus was produced in Ernest Rutherford’s laboratory in 1919 by a transmutation reaction, the bombardment of one type of nuclei with other nuclei or with neutrons. Rutherford bombarded nitrogen-14 atoms with high-speed α particles from a natural radioactive isotope of radium and observed protons being...
03:18Radioactivity and Nuclear Equations
Nuclear chemistry is the study of reactions that involve changes in nuclear structure. The nucleus of an atom is composed of protons and, except for hydrogen, neutrons. The number of protons in the nucleus is called the atomic number (Z) of the element, and 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 isotopes of the same element.
A nuclide of an element has a specific number of protons and...
A nuclide of an element has a specific number of protons and...
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...
02:48Radioactive Decay and Radiometric Dating
Radioactivity is a spontaneous disintegration of an unstable nuclide and is a random process, as all the nuclei in the sample do not decay simultaneously. The number of disintegrations per unit time is called the activity (A), which is directly proportional to the number of nuclei in the sample. The decay constant (λ) is an average probability of decay per nucleus in unit time.
04:00Periodic Classification of the Elements
The periodic table arranges atoms based on increasing atomic number so that elements with the same chemical properties recur periodically. When their electron configurations are added to the table, a periodic recurrence of similar electron configurations in the outer shells of these elements is observed. Because they are in the outer shells of an atom, valence electrons play the most important role in chemical reactions. The outer electrons have the highest energy of the electrons in an atom...