To understand mantle dynamics, it is important to determine the rheological properties of bridgmanite, the dominant mineral in Earth's mantle. Nevertheless, experimental data on the viscosity of bridgmanite are quite limited due to experimental difficulties. Here, we report viscosity and deformation mechanism maps of bridgmanite at the uppermost lower mantle conditions obtained through in situ stress-strain measurements of bridgmanite using deformation apparatuses with the Kawai-type cell. Bridgmanite would be the hardest among mantle constituent minerals even under nominally dry conditions in the dislocation creep region, consistent with the observation that the lower mantle is the hardest layer. Deformation mechanism maps of bridgmanite indicate that grain size of bridgmanite and stress conditions at top of the lower mantle would be several millimeters and ~10 Pa to realize viscosity of 10 Pa·s, respectively. This grain size of bridgmanite suggests that the main part of the lower mantle is isolated from the convecting mantle as primordial reservoirs.
Download full-text PDF |
Source |
|---|---|
| http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8967219 | PMC |
| http://dx.doi.org/10.1126/sciadv.abm1821 | DOI Listing |
Publication Analysis
Top Keywords
Similar Publications
Infected Primary Bone Mantle Cell Lymphoma with Multiple Vertebral Involvement.
Int J Hematol Oncol Stem Cell Res
October 2024
Department of Endocrinology and Internal Medicine, Tahar Sfar University Hospital, Mahdia, Tunisia.
Primary vertebral lymphoma is an exceedingly rare entity. We hereby report a case of a 67-year-old male who presented to our department with fever, weight loss, and progressively worsening lower back pain radiating to the right hip. Physical examination showed pain on percussion of the dorsal and lumbar spine and tenderness on palpation of the right upper thigh area.
View Article and Find Full Text PDFNew MgSiO_{4}H_{2} Phases as Potential Primary Water Carriers into the Deep Earth.
Phys Rev Lett
November 2024
Key Laboratory of Material Simulation Methods and Software of Ministry of Education, College of Physics, Jilin University, Changchun 130012, China.
Dense hydrous magnesium silicate MgSiO_{4}H_{2} is widely regarded as a primary water carrier into the deep Earth. However, the stability fields of MgSiO_{4}H_{2} based on the prevailing structure model are narrower than experimental results at relevant pressure and temperature (P-T) conditions, casting doubts about this prominent mineral as a water carrier into the great depths of the Earth. Here, we report on an advanced structure search that identifies two new crystal structures, denoted as α- and β-MgSiO_{4}H_{2}, that are stable over unprecedentedly wide P-T conditions of 17-68 GPa and up to 1860 K, covering the entire experimentally determined range.
View Article and Find Full Text PDFEffect of bridgmanite-ferropericlase grain size evolution on Earth's average mantle viscosity: implications for mantle convection in early and present-day Earth.
Prog Earth Planet Sci
December 2024
School of Earth Sciences, Zhejiang University, Hangzhou, China.
Recent experimental investigations of grain size evolution in bridgmanite-ferropericlase assemblages have suggested very slow growth for these bimodal phases. Despite numerous speculations on grain size-dependent viscosity, a comprehensive test with realistic grain size evolution parameters compatible with the lower mantle has been lacking. In this study, we develop self-consistent 2-D spherical half-annulus geodynamic models of Earth's evolution using the finite volume code StagYY to assess the role of grain size on lower mantle viscosity.
View Article and Find Full Text PDFQuantifying the effects of the microphysical hygroscopic restructuring of soot on ensemble optical properties and satellite aerosol optical depth retrievals.
Sci Total Environ
December 2024
Research Centre for Environmental Changes, Academia Sinica, Taipei, Taiwan.
Black carbon, or soot, significantly contributes to atmospheric light absorption due to its low single scattering albedo (SSA). This study investigates the impact of soot's hygroscopic restructuring on satellite remote sensing, focusing on radiative forcing, top-of-atmosphere (TOA) reflectance, and aerosol optical depth (AOD) retrievals. We characterized soot aging using relative humidity (RH) growth factor functions and modeled fresh and aging soot aggregates using a cluster-cluster aggregation algorithm.
View Article and Find Full Text PDFArticle Synopsis
- Lisocabtagene maraleucel (liso-cel) is an effective autologous T-cell therapy for various types of lymphoma, showing high patient satisfaction with outpatient monitoring, which is more cost-effective than inpatient care.
- The successful implementation of outpatient monitoring programs for liso-cel requires collaboration among nurses, advanced practice providers (APPs), and other stakeholders, supported by thorough training and flexible processes.
- Key features for effective outpatient monitoring include same-day discharge after infusion, ongoing patient availability for follow-up, and a coordinated approach to manage adverse events across different facilities.
Want AI Summaries of new PubMed Abstracts delivered to your In-box?
Enter search terms and have AI summaries delivered each week - change queries or unsubscribe any time!