Video Experimental Relacionado
Updated: Jul 11, 2026
08:14
Atom Probe Tomography Analysis of Exsolved Mineral Phases
Published on: October 25, 2019
40Ar/39Ar Edad de las tektitas del límite cretáceo-terciario de Haití
Science (New York, N.Y.)
|June 14, 1991
Resumen
La datación argón-argon de tektitas y sanidinas de Haití y Montana confirma que el evento de impacto del límite Cretácico-Terciario (K-T) ocurrió hace 64,5 millones de años, alineando las líneas de tiempo geológicas y de impacto.
Área de la Ciencia:
- Geocronología Geocronología.
- Paleontología Paleontología.
- El cráter de impacto es el cráter de impacto.
Sus antecedentes:
- El límite entre el Cretácico y el Terciario (K-T) marca un evento significativo de extinción masiva.
- Determinar el momento preciso del límite K-T y los eventos de impacto asociados es crucial para comprender la dinámica de la extinción.
Objetivo del estudio:
- Para fechar con precisión el límite K-T y el evento de impacto de Chicxulub utilizando técnicas de datación radiométrica.
- Para establecer la correlación temporal entre el límite K-T, las capas de roca sedimentaria y el evento de impacto.
Principales métodos:
- La geocronología argón-argon ((40) Ar/ ((39) Ar) se empleó para datar las tektitas encontradas en las rocas sedimentarias marinas haitianas.
- La sanidina de una capa de bentonita por encima del límite K-T en las rocas sedimentarias continentales de Montana también fue fechada utilizando el análisis (40) Ar / (39) Ar.
Principales resultados:
- Las tektitas de Haití arrojaron una edad precisa (40) Ar / (39) Ar de 64,5 +/- 0,1 millones de años atrás.
- La sanidina de la capa de bentonita de Montana proporcionó una edad indistinguible de 64.6 +/- 0.2 millones de años atrás.
- Estos resultados establecen la naturaleza contemporánea del límite K-T y el evento de impacto.
Conclusiones:
- El evento de impacto del límite K-T está definitivamente fechado hace aproximadamente 64,5 millones de años.
- El estudio confirma la sincronicidad del evento de impacto con la extinción masiva K-T.
- Datos geocronológicos precisos resuelven preguntas de larga data sobre el momento de esta transición geológica y biológica crítica.
Videos de Conceptos Relacionados
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.
02:56The Fossil Record
The fossil record documents only a small fraction of all organisms that have ever inhabited Earth. Fossilization is a rare process, and most organisms never become fossils. Moreover, the fossil record only exhibits fossils that have been discovered. Nevertheless, sedimentary rock fossils of long-lived, abundant, hard-bodied organisms dominate the fossil record. These fossils offer valuable information, such as an organism's physical form, behavior, and age. Studying the fossil record helps...
01:50Global Climate Change
Throughout its ~4.5 billion year history, the Earth has experienced periods of warming and cooling. However, the current drastic increase in global temperatures is well outside of the Earth’s cyclic norms, and evidence for human-caused global climate change is compelling. Paleoclimatology, the study of ancient climate conditions, provides ample evidence for human-caused global climate change by comparing recent conditions with those in the past.
02:41Telomeres and Telomerase
In eukaryotic DNA replication, a single-stranded DNA fragment remains at the end of a chromosome after the removal of the final primer. This section of DNA cannot be replicated in the same manner as the rest of the strand because there is no 3’ end to which the newly synthesized DNA can attach. This non-replicated fragment results in gradual loss of the chromosomal DNA during each cell duplication. Additionally, it can induce a DNA damage response by enzymes that recognize single-stranded DNA.
02:41Telomeres and Telomerase
In eukaryotic DNA replication, a single-stranded DNA fragment remains at the end of a chromosome after the removal of the final primer. This section of DNA cannot be replicated in the same manner as the rest of the strand because there is no 3’ end to which the newly synthesized DNA can attach. This non-replicated fragment results in gradual loss of the chromosomal DNA during each cell duplication. Additionally, it can induce a DNA damage response by enzymes that recognize single-stranded DNA.
02:06Conditions on Early Earth
Around 4 billion years ago, oceans began to condense on earth while volcanic eruptions released nitrogen, carbon dioxide, methane, ammonia, and hydrogen into the primordial atmosphere. However, organisms with the characteristics of life were not initially present on earth. Scientists have used experimentation to determine how organisms evolved that could grow, reproduce, and maintain an internal environment.