Sinuous stromatolites of the Chandi Formation, Chattisgarh Basin, India: their origin and implications for Mesoproterozoic seawater

2021 ◽  
pp. 1-14
Author(s):  
Mirosław Słowakiewicz ◽  
Amlan Banerjee ◽  
Sarbani Patranabis-Deb ◽  
Gautam Kumar Deb ◽  
Maurice E. Tucker
Keyword(s):  
Trace Elements ◽  
Rare Earth ◽  
North America ◽  
Life Forms ◽  
Rhythmic Pattern ◽  
Terrigenous Material ◽  
Seawater Chemistry ◽  
Detrital Sediment ◽  
Geochemical Analyses

Abstract Remnants of some of the planet’s most ancient life forms, stromatolites in the late Mesoproterozoic sea of the Chattisgarh Basin, India, preserve a conspicuous sinuous pattern. They occur as successive biostromes, 10–30 cm thick, separated by 2–5-cm-thick marly layers and discrete bioherms up to several metres thick and 20 m across. Stromatolite columns in the Chandi Formation are 5–10 cm high, sinuous, inclined and straight, with both branched and non-branched types. These stromatolites are composed of calcite micrite and show well defined light and dark laminae with evidence of erosion between lamina sets. The column sinuosity probably originated as a response to changes in direction and strength of currents. Successive flat beds of stromatolite (biostromes), separated by marl/clay horizons, impart a rhythmic pattern to the succession. The Chandi sinuous stromatolite columns resemble those occurring in China, North America and Siberia, of a comparable age, suggesting that similar marine conditions of stromatolite formation might have been operating in the late Mesoproterozoic seas worldwide. However, the petrographic and sedimentological analyses of these stromatolites indicate their development through in situ production of carbonate with some trapping and binding of detrital sediment. As a result of the presence of terrigenous material within the stromatolites, whole-rock geochemical analyses for trace elements and rare earth elements cannot be used for interpretation of seawater chemistry and the redox conditions at the time.

scholarly journals Lanthanum Diffusion in Fluorapatite at 400 °C, 50 MPa and 4–16 wt %

Separations ◽  
2021 ◽  
Vol 8 (6) ◽  
pp. 72
Author(s):  
Xiqiang Liu ◽  
Hui Zhang ◽  
Yunlong Liu
Keyword(s):  
Experimental Study ◽  
Diffusion Coefficient ◽  
Rare Earth ◽  
Rare Earth Elements ◽  
Great Influence ◽  
Hydrothermal Solution ◽  
Coefficient Increase ◽  
Geochemical Analyses ◽  
C 50

Apatite is an important carrier of rare earth elements (REEs) and phosphorite is a potential REEs resource. However, the influence of hydrothermal fluids on the migration and enrichment of REE in apatite remains controversial. The experimental study of the interaction between REE-bearing fluid and apatite is one of the essential ways to understand the chemical behavior of rare earth elements in apatite. In this study, we conducted the fluid–mineral reaction experimental study (at 400 °C, 50 MPa and 4–16 wt %) between high lanthanum (La) content hydrothermal solution and low REE content to reveal the influence of different salinities on the diffusion of rare earth elements in fluorapatite. Based on in situ geochemical analyses of experimental products, we show that the diffusion coefficients of La in fluorapatite are between 3.24 × 10−15 and 5.88 × 10−15 m2/s. The salinity of the fluid has a great influence on the diffusion coefficient, with the increase of salinity, the diffusion coefficient increase.

ELEKTRON EQ2

Alloy Digest ◽  
2015 ◽  
Vol 64 (9) ◽  
Keyword(s):  
Corrosion Resistance ◽  
Rare Earth ◽  
High Temperature ◽  
Magnesium Alloy ◽  
North America ◽  
Earth Element ◽  
High Strength ◽  
Heat Treating ◽  
Bend Strength ◽  
Temperature Performance

Abstract Elektron EQ21 is a casting high strength magnesium alloy developed as a heat treatable alloy with rare earth element additions. This datasheet provides information on composition, physical properties, hardness, elasticity, tensile properties, and compressive, shear, and bend strength as well as creep. It also includes information on high temperature performance and corrosion resistance as well as casting, forming, heat treating, machining, joining, and surface treatment. Filing Code: Mg-80. Producer or source: Magnesium Elektron Wrought Products, North America.

GEOCHEMISTRY OF RARE EARTH AND OTHER TRACE ELEMENTS IN CHINESE OIL SHALE

Oil Shale ◽  
2014 ◽  
Vol 31 (3) ◽  
pp. 266 ◽  
Author(s):  
W QING ◽  
B JINGRU ◽  
G JIANXIN ◽  
W YAN-ZHEN ◽  
L SHUYUAN
Keyword(s):  
Trace Elements ◽  
Rare Earth ◽  
Oil Shale

Synthetic zircon doped with hafnium and rare earth elements: A reference material for in situ hafnium isotope analysis

2011 ◽  
Vol 286 (1-2) ◽  
pp. 32-47 ◽  
Author(s):  
Christopher M. Fisher ◽  
John M. Hanchar ◽  
Scott D. Samson ◽  
Bruno Dhuime ◽  
Janne Blichert-Toft ◽  
...  
Keyword(s):  
Rare Earth ◽  
Reference Material ◽  
Rare Earth Elements ◽  
Isotope Analysis

scholarly journals Start-up Strategies for Anaerobic Ammonia Oxidation (Anammox) in In-Situ Nitrogen Removal from Polluted Groundwater in Rare Earth Mining Areas

2021 ◽  
Vol 13 (8) ◽  
pp. 4591
Author(s):  
Shuanglei Huang ◽  
Daishe Wu
Keyword(s):  
Rare Earth ◽  
Low Temperature ◽  
Removal Efficiency ◽  
Nitrogen Removal ◽  
Ex Situ ◽  
High Concentration ◽  
Low Concentration ◽  
Start Up ◽  
Anammox Activity

The tremendous input of ammonium and rare earth element (REE) ions released by the enormous consumption of (NH4)2SO4 in in situ leaching for ion-adsorption RE mining caused serious ground and surface water contamination. Anaerobic ammonium oxidation (anammox) was a sustainable in situ technology that can reduce this nitrogen pollution. In this research, in situ, semi in situ, and ex situ method of inoculation that included low-concentration (0.02 mg·L−1) and high-concentration (0.10 mg·L−1) lanthanum (La)(III) were adopted to explore effective start-up strategies for starting up anammox reactors seeded with activated sludge and anammox sludge. The reactors were refrigerated for 30 days at 4 °C to investigate the effects of La(III) during a period of low-temperature. The results showed that the in situ and semi in situ enrichment strategies with the addition of La(III) at a low-concentration La(III) addition (0.02 mg·L−1) reduced the length of time required to reactivate the sludge until it reached a state of stable anammox activity and high nitrogen removal efficiency by 60–71 days. The addition of La(III) promoted the formation of sludge floc with a compact structure that enabled it to resist the adverse effects of low temperature and so to maintain a high abundance of AnAOB and microbacterial community diversity of sludge during refrigeration period. The addition of La(III) at a high concentration caused the cellular percentage of AnAOB to decrease from 54.60 ± 6.19% to 17.35 ± 6.69% during the enrichment and reduced nitrogen removal efficiency to an unrecoverable level to post-refrigeration.

Engaging with the science and politics of biodiversity futures: a literature review

2021 ◽  
pp. 1-8
Author(s):  
Carina Wyborn ◽  
Elena Louder ◽  
Mike Harfoot ◽  
Samantha Hill
Keyword(s):  
Human Life ◽  
Global Environmental Change ◽  
Life Forms ◽  
Trade Offs ◽  
Global Environmental ◽  
Science And Politics ◽  
Science Community ◽  
Impact On Biodiversity ◽  
Made In

Summary Future global environmental change will have a significant impact on biodiversity through the intersecting forces of climate change, urbanization, human population growth, overexploitation, and pollution. This presents a fundamental challenge to conservation approaches, which seek to conserve past or current assemblages of species or ecosystems in situ. This review canvases diverse approaches to biodiversity futures, including social science scholarship on the Anthropocene and futures thinking alongside models and scenarios from the biophysical science community. It argues that charting biodiversity futures requires processes that must include broad sections of academia and the conservation community to ask what desirable futures look like, and for whom. These efforts confront political and philosophical questions about levels of acceptable loss, and how trade-offs can be made in ways that address the injustices in the distribution of costs and benefits across and within human and non-human life forms. As such, this review proposes that charting biodiversity futures is inherently normative and political. Drawing on diverse scholarship united under a banner of ‘futures thinking’ this review presents an array of methods, approaches and concepts that provide a foundation from which to consider research and decision-making that enables action in the context of contested and uncertain biodiversity futures.

Lithospheric roots beneath western Laurentia: the geochemical signal in mantle garnets

2003 ◽  
Vol 40 (8) ◽  
pp. 1027-1051 ◽  
Author(s):  
D Canil ◽  
D J Schulze ◽  
D Hall ◽  
B C Hearn Jr. ◽  
S M Milliken
Keyword(s):  
Rare Earth ◽  
North America ◽  
Trace Element ◽  
Earth Element ◽  
Geochemical Data ◽  
Trace Element Data ◽  
Mantle Lithosphere ◽  
Western North America ◽  
Wyoming Province ◽  
Thick Mantle

This study presents major and trace element data for 243 mantle garnet xenocrysts from six kimberlites in parts of western North America. The geochemical data for the garnet xenocrysts are used to infer the composition, thickness, and tectonothermal affinity of the mantle lithosphere beneath western Laurentia at the time of kimberlite eruption. The garnets record temperatures between 800 and 1450°C using Ni-in-garnet thermometry and represent mainly lherzolitic mantle lithosphere sampled over an interval from about 110–260 km depth. Garnets with sinuous rare-earth element patterns, high Sr, and high Sc/V occur mainly at shallow depths and occur almost exclusively in kimberlites interpreted to have sampled Archean mantle lithosphere beneath the Wyoming Province in Laurentia, and are notably absent in garnets from kimberlites erupting through the Proterozoic Yavapai Mazatzal and Trans-Hudson provinces. The similarities in depths of equilibration, but differing geochemical patterns in garnets from the Cross kimberlite (southeastern British Columbia) compared to kimberlites in the Wyoming Province argue for post-Archean replacement and (or) modification of mantle beneath the Archean Hearne Province. Convective removal of mantle lithosphere beneath the Archean Hearne Province in a "tectonic vise" during the Proterozoic terminal collisions that formed Laurentia either did not occur, or was followed by replacement of thick mantle lithosphere that was sampled by kimberlite in the Triassic, and is still observed there seismically today.

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