Geophysics & Earth's Interior
The study of seismic waves, including P-waves and S-waves, allows geophysicists to infer the physical properties and state of matter within Earth's deep interior, including the liquid outer core.
What is seismology?
The chemical composition of magma determines the type of igneous rock formed upon cooling.
What is source rock composition (or differentiation)?
This method uses the ratio of parent and daughter isotopes to determine the absolute age of rocks.
What is radiometric dating?
This deep-ocean current system is driven by differences in water temperature and salinity, playing a vital role in global climate.
What is thermohaline circulation?
Research on seismic anisotropy in the innermost inner core suggests the presence of a distinct internal shell, potentially due to this past event in the inner core's history, requiring understanding of both Earth's internal structure and its formation timeline.
What is a change in the inner core's growth regime (or a phase transition during early Earth differentiation)?
The concept that the Earth's crust is underlain by material that behaves in a fluid manner, allowing the crust to float at an equilibrium level.
What is isostasy?
The chemical interaction between rock and water, often causing significant weathering and alteration.
What is hydrolysis?
The principle used to correlate rock layers over large distances based on the presence of similar fossil assemblages.
What is the Principle of Faunal Succession?
Research in the Drake Passage frontal regions indicates that increased wind stress does not accelerate net transport due to compensating trends.
What is the Drake Passage?
The existence of chemosynthetic ecosystems at deep-sea hydrothermal vents demonstrates the vital interplay between these three Earth spheres, operating independently of solar energy at the base of the food web.
What are the geosphere (heat/chemicals), hydrosphere (water circulation), and biosphere (organisms)?
The generation of Earth's magnetic field within the outer core, often described using fluid dynamics of liquid iron.
What is the geodynamo?
The Argyle diamond deposit was emplaced into an ancient rift zone triggered by this major geological event.
What is supercontinent breakup?
This term refers to periods in Earth's history when no magnetic field reversals occurred for millions of years.
What are superchrons?
The presence of chemosynthetic communities at hydrothermal vents on the seafloor demonstrates this unique interaction between Earth's systems.
What is the interaction between the geosphere and the biosphere (or hydrosphere)?
This major geological event, which occurred roughly 252 million years ago and marked the end of the Paleozoic Era, was likely exacerbated by widespread volcanism and resulted in a severe climate crisis.
What is the Permian-Triassic extinction event?
The observation of free oscillations (normal modes) of the Earth after large earthquakes provides direct evidence about these properties of Earth's interior layers.
What are the elastic properties (or density and rigidity)?
The study of the chemical properties and behavior of elements in Earth's crust and mantle, including the processes that shape their distribution.
What is geochemistry?
This concept, which links astronomical cycles to long-term climate variations, provides a framework for understanding Ice Ages.
What are Milankovitch cycles?
Analysis of historical and Argo observations reveals that warming of mode and intermediate water layers contributes most to global upper ocean warming.
What is mode and intermediate water warming?
The collapse of a massive stellar core, following a supernova, can lead to the formation of these two distinct types of incredibly dense celestial remnants, depending on the remaining mass.
What are a neutron star or a black hole?
The presence of multiply-reverberating seismic body waves through the Earth's center has confirmed the existence of this distinct internal structure.
What is an innermost inner core?
A 2.35-billion-year-old Moon rock found in Africa is rewriting our understanding of this process on the early Moon.
What is lunar volcanism?
This method of absolute dating, while powerful for determining the age of igneous and metamorphic rocks, cannot be directly applied to most sedimentary rocks and requires dating associated igneous formations for an indirect age.
What is radiometric dating?