Las temperaturas del mar profundo del Cenozoico y los volúmenes globales de hielo de Mg/Ca en calcita bentónica foraminiferal
Video Experimental Relacionado
Updated: Jul 10, 2026
10:18
Dynamic Pore-scale Reservoir-condition Imaging of Reaction in Carbonates Using Synchrotron Fast Tomography
Published on: February 21, 2017
Lear1, Elderfield, Wilson
1Department of Earth Sciences, University of Cambridge, Downing Street, Cambridge CB2 3EQ, UK.
Science (New York, N.Y.)
|January 15, 2000
Resumen
Las temperaturas de las profundidades del mar se enfriaron 12°C durante 50 millones de años, revelando un rápido crecimiento del hielo antártico hace 34 millones de años. Estos datos climáticos antiguos ofrecen información sobre la historia térmica de la Tierra y la dinámica de la capa de hielo.
Área de la Ciencia:
- La paleoceanografía es la paleoceanografía.
- Ciencias del clima Ciencias del clima Ciencias del clima
- La geoquímica es la geoquímica.
Sus antecedentes:
- Comprender las temperaturas pasadas de las profundidades marinas es crucial para reconstruir la historia climática de la Tierra.
- Los bentónicos foraminíferos proporcionan valiosos proxies para reconstruir las condiciones oceánicas pasadas.
Objetivo del estudio:
- Para generar un registro de temperatura de aguas profundas que abarca los últimos 50 millones de años.
- Para investigar la relación entre las temperaturas de aguas profundas y la formación de la capa de hielo de la Antártida.
Principales métodos:
- Utilizó la relación magnesio/calcio (Mg/Ca) en el calcito bentónico foraminiferal.
- Se correlacionó el registro de temperatura Mg / Ca con el registro del isótopo de oxígeno bentónico (delta 18O).
Principales resultados:
- Estableció un registro de temperatura de aguas profundas que muestra un enfriamiento general de aproximadamente 12 ° C.
- Identificó cuatro períodos distintos de enfriamiento significativo en los últimos 50 millones de años.
- Se demostró que la mayor acumulación inicial de hielo antártico se produjo rápidamente a principios del Oligoceno (hace 34 millones de años).
Conclusiones:
- El registro de magnesio/calcio es muy similar al registro de isótopos de oxígeno bentónico.
- El crecimiento del hielo antártico del Oligoceno temprano no fue inmediatamente precedido por una caída en las temperaturas de aguas profundas.
- Este estudio refina nuestra comprensión de la evolución del clima del Cenozoico y el inicio de la edad de hielo.
Videos de Conceptos Relacionados
01:14The Carbon Cycle
Carbon is the basis of all organic matter on Earth, and is recycled through the ecosystem in two primary processes: one in which carbon is exchanged among living organisms, and one in which carbon is cycled over long periods of time through fossilized organic remains, weathering of rocks, and volcanic activity. Human activities, including increased agricultural practices and the burning of fossil fuels, has greatly affected the balance of the natural carbon cycle.
04:08Determining the pH of Salt Solutions
The pH of a salt solution is determined by its component anions and cations. Salts that contain pH-neutral anions and the hydronium ion-producing cations form a solution with a pH less than 7. For example, in ammonium nitrate (NH4NO3) solution, NO3− ions do not react with water whereas NH4+ ions produce the hydronium ions resulting in the acidic solution. In contrast, salts that contain pH-neutral cations and the hydroxide ion-producing anions form a solution with a pH greater than 7. For...
03:24Common Ion Effect
Compared with pure water, the solubility of an ionic compound is less in aqueous solutions containing a common ion (one also produced by dissolution of the ionic compound). This is an example of a phenomenon known as the common ion effect, which is a consequence of the law of mass action that may be explained using Le Châtelier’s principle. Consider the dissolution of silver iodide:
03:07Solubility Equilibria
Solubility equilibria are established when the dissolution and precipitation of a solute species occur at equal rates. These equilibria underlie many natural and technological processes, ranging from tooth decay to water purification. An understanding of the factors affecting compound solubility is, therefore, essential to the effective management of these processes. This section applies previously introduced equilibrium concepts and tools to systems involving dissolution and precipitation.
The...
The...
01:24Carbonation Shrinkage
Atmospheric CO2 penetrates the concrete's pores and, in the presence of moisture, forms carbonic acid, which then reacts with calcium hydroxide in the hydrated cement, forming calcium carbonate. This process reduces the concrete's volume and is termed carbonation shrinkage.
The concrete's permeability is slightly reduced as calcium carbonate produced during the reaction fills its pores. Furthermore, its strength is slightly enhanced as the water released during the reaction facilitates the...
The concrete's permeability is slightly reduced as calcium carbonate produced during the reaction fills its pores. Furthermore, its strength is slightly enhanced as the water released during the reaction facilitates the...
01:18Deep Sea Microbial Ecology
The deep ocean and its underlying sediments represent vast, largely unexplored microbial habitats that extend far beyond the sunlit photic zone. The photic (euphotic) zone typically spans the upper ~100–200 meters of pelagic waters in the open ocean, but its depth varies geographically and seasonally, where sufficient light supports photosynthetic life. Below this lies the deep sea, spanning roughly 1000–6000 meters (bathypelagic to abyssal zones), with deeper hadal trenches extending beyond...