Phys.org September 28, 2024 The Pacific large low-shear-velocity province (LLSVP) hosts multiple internal anomalies, including a notable gap between the central and eastern Pacific. The cause of the structural gap remains unconstrained. An international team of researchers (USA – University of Maryland, Canada) used a dense set of SS precursors (seismic waves) identify an anomalously thick mantle transition zone east of the East Pacific Rise directly above this structural gap. The area of the thickened transition zone exhibited faster-than-average velocities according to recent tomographic images, suggesting perturbed post olivine phase boundaries shifting in response to lowered temperatures. The researchers attributed […]
Tag Archives: Geology
Earth scientists describe a new kind of volcanic eruption
Science Daily May 27, 2024 Explosive volcanic eruptions driven by magmatic fragmentation or steam expansion produce hazardous atmospheric plumes composed of tephra particles, hot gas, and entrained air. However, an eruption mechanism outside this phreatic–magmatic spectrum was suggested by a sequence of 12 explosive eruptions in May 2018 at Kīlauea, Hawaii, that occurred during the early stages of caldera collapse and produced atmospheric plumes reaching 8 km above the vent. A team of researchers in the US (US Geological Survey Volcano Science Center California Volcano Observatory, University of Oregon, USGS Portland, USGS Vancouver, WA) used seismic inversions for reservoir pressure as […]
Scientists isolate early-warning tremor pattern in lab-made earthquakes
Phys.org October 25, 2023 An international team of researchers (USA – UT Austin, Pennsylvania State University, University of Nevada, Italy) measured waveform similarity and pairwise differential travel-times (DTT) between acoustic emission (AEs) throughout the seismic cycle. AEs broadcasted prior to slow labquakes had small DTT and high waveform similarity relative to fast labquakes. They showed that during slow stick-slip, the fault never fully locked, and waveform similarity and pairwise differential travel times did not evolve throughout the seismic cycle. In contrast, fast laboratory earthquakes were preceded by a rapid increase in waveform similarity late in the seismic cycle and a […]
How to look thousands of kilometers deep into the Earth
Phys.org February 21, 2022 To understand how Earth has cooled and produced a solid mantle and crust, we need to know the physical properties of molten rocks at extreme pressure. An international team of researchers (Germany, UK) used the brightness of reflection from a multicolor laser to measure the refractive index of SiO2 glass and the path length of the laser inside the sample at pressures of up to 110 gigapascals, pressures similar to that at the depth of more than 2000 km in the Earth. These measurements yielded the refractive index of SiO2 glass and provided key information to […]
Geologists solve puzzle that could predict valuable rare earth element deposits
Science Daily October 9, 2020 Carbonatites and associated rocks are the main source of rare earth elements (REEs). REE mineralization occurs in hydrothermal assemblages within or near carbonatites, suggesting aqueous transport of REE. An international team of researchers (UK, Australia) conducted experiments from 1200°C and 1.5 GPa to 200°C and 0.2 GPa using light and heavy REE, crystallizing fluorapatite intergrown with calcite through dolomite to ankerite. All experiments contained solutions with anions previously thought to mobilize REE (chloride, fluoride, and carbonate), but REEs were extensively soluble only when alkalis were present. Dysprosium was more soluble than lanthanum when alkali complexed. […]
A billion years missing from geologic record: Where it may have gone
Science Daily May 7, 2020 The Great Unconformity, as it is known, accounts for more than one billion years of missing rock in certain places. Scientists have developed several hypotheses to explain how, and when, this staggering amount of material may have been eroded. Using the ratio of helium to thorium and uranium in certain minerals as a paleo-thermometer a team of researchers in the US (University of Colorado, UC Santa Barbara) tracked how rock moved in the crust as it was buried and eroded through the ages. They extracted grains of a particularly resilient mineral, zircon, from the stone […]
Updated World Magnetic Model shows magnetic north pole continuing to push toward Siberia
Phys.org December 17, 2019 The team of researchers that maintain the World Magnetic Model (WMM) has updated it and released it a year ahead of schedule due to the speed with which the pole is moving. The model is normally updated every five years. The model is maintained jointly by the U.S. National Oceanic and Atmospheric Administration and the British Geological Survey. Data for the model comes from satellites and 160 land-based observatories. It is currently not known why the poles drift nor is the mechanism driving them understood. Since 1831 the north magnetic pole has traveled 1,400 miles since […]
A New Study Just Revealed That Earth’s Core Is Actually Leaking
Science Alert July 11, 2019 By looking at very small variations in the ratio of isotopes of the element tungsten, an international team of researchers (Canada, France, USA – UC Davies, Florida State University, UT Houston, Australia) suggests that some core material does transfer into the base of these mantle plumes, and the core has been leaking this material for the past 2.5 billion years. The study gives us a tracer that can be used to investigate core-mantle interaction and the change in the internal dynamics of our planet, and which can boost our understanding of how and when the […]