scholarly journals Sediment-Peridotite Reaction Controls Fore-Arc Metasomatism and Arc Magma Geochemical Signatures

Geosciences ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 372
Author(s):  
Michael W. Förster ◽  
Yannick Bussweiler ◽  
Dejan Prelević ◽  
Nathan R. Daczko ◽  
Stephan Buhre ◽  
...  
Keyword(s):  
Trace Elements ◽  
Low Temperatures ◽  
Slab Surface ◽  
High Field Strength ◽  
Arc Magmas ◽  
Selective Incorporation ◽  
Partial Melts ◽  
Subducting Slab ◽  
Arc Magma ◽  
Distribution Of Trace Elements

Subduction of oceanic crust buries an average thickness of 300–500 m of sediment that eventually dehydrates or partially melts. Progressive release of fluid/melt metasomatizes the fore-arc mantle, forming serpentinite at low temperatures and phlogopite-bearing pyroxenite where slab surface reaches 700–900 °C. This is sufficiently high to partially melt subducted sediments before they approach the depths where arc magmas are formed. Here, we present experiments on reactions between melts of subducted sediments and peridotite at 2–6 GPa/750–1100 °C, which correspond to the surface of a subducting slab. The reaction of volatile-bearing partial melts derived from sediments with depleted peridotite leads to separation of elements and a layered arrangement of metasomatic phases, with layers consisting of orthopyroxene, mica-pyroxenite, and clinopyroxenite. The selective incorporation of elements in these metasomatic layers closely resembles chemical patterns found in K-rich magmas. Trace elements were imaged using LA-ICP-TOFMS, which is applied here to investigate the distribution of trace elements within the metasomatic layers. Experiments of different duration enabled estimates of the growth of the metasomatic front, which ranges from 1–5 m/ky. These experiments explain the low contents of high-field strength elements in arc magmas as being due to their loss during melting of sedimentary materials in the fore-arc.

scholarly journals Tracking slab surface temperatures with electrical conductivity of glaucophane

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Geeth Manthilake ◽  
Ye Peng ◽  
Kenneth T. Koga ◽  
Mainak Mookherjee
Keyword(s):  
Electrical Conductivity ◽  
Low Temperatures ◽  
Silicate Melts ◽  
Slab Surface ◽  
Dehydration Melting ◽  
Hydrous Minerals ◽  
First Order ◽  
Slab Temperature ◽  
Thermodynamic Instability ◽  
Subducting Slab

AbstractSlab surface temperature is one of the key parameters that incur first-order changes in subduction dynamics. However, the current thermal models are based on empirical thermal parameters and do not accurately capture the complex pressure–temperature paths of the subducting slab, prompting significant uncertainties on slab temperature estimations. In this study, we investigate whether the dehydration-melting of glaucophane can be used to benchmark the temperature in the slab. We observe that dehydration and melting of glaucophane occur at relatively low temperatures compared to the principal hydrous phases in the slab and produce highly conductive Na-rich melt. The electrical properties of glaucophane and its dehydration products are notably different from the hydrous minerals and silicate melts. Hence, we conclude that the thermodynamic instability of glaucophane in the slab provides a unique petrological criterion for tracking temperature in the present-day subduction systems through magnetotelluric profiles.

scholarly journals The potential of trace elements mapping in child’s natal tooth by laser ablation-ICPMS method

2021 ◽  
Author(s):  
Aneta Olszewska ◽  
Anetta Hanć
Keyword(s):  
Trace Elements ◽  
Spatial Distribution ◽  
Quantitative Assessment ◽  
Toxic Elements ◽  
Tooth Enamel ◽  
Perinatal Period ◽  
Potentially Toxic Elements ◽  
Metal Exposure ◽  
Icp Ms ◽  
Distribution Of Trace Elements

Abstract Purpose Tooth enamel might provide past chronological metabolic, nutritional status and trace metal exposure during development. Thus, the trace elements distribution embedded in tooth tissues represents an archive of the environmental conditions. The choice of biomarker is estimated as critical to the measurement of metal exposure. Natal teeth are defined as teeth being present at birth. Methods LA-ICP-MS provides a quantitative assessment of spatial distribution of trace elements in a natal tooth. The objective of the current study was to compare concentrations of building and other elements in a rare but reliable and valid biomarker - natal tooth. Results It have been reported presence of potentially toxic elements: Pb, Cu, Mn, Cd, Ni distributed in prenatally and perinatally formed enamel and dentine. Conclusions Analyses of deciduous enamel can provide answers into individuals’ earliest development, including critical pre- and perinatal period.

Distribution of trace elements between carbonate and non-carbonate phases of limestone

1977 ◽  
Vol 34 (1) ◽  
pp. 39-50 ◽  
Author(s):  
P.P. Parekh ◽  
P. Möller ◽  
P. Dulski ◽  
W.M. Bausch
Keyword(s):  
Trace Elements ◽  
Distribution Of Trace Elements

Mineralogical controls on the distribution of trace elements in metasomatized peridotite enclaves from Planany, Czech Republic

2007 ◽  
Vol 71 (1) ◽  
pp. 81-91 ◽  
Author(s):  
J. V. Owen ◽  
J. Dostal ◽  
M. Fisera
Keyword(s):  
Trace Elements ◽  
Czech Republic ◽  
Reference Frame ◽  
Outer Layer ◽  
Reaction Zones ◽  
Host Rocks ◽  
Distribution Of Trace Elements

AbstractSmall (m-scale) peridotite enclaves at Planany (central Czech Republic) are separated from their gneissic host rocks by a narrow (cm-scale) reaction rim comprising an inner, tremolite + phlogopite zone and an outer, essentially monomineralic phlogopite zone. Both retain an Mg# very similar to that of the peridotite (Mg# = 81), but relative to this reference frame, show large increases in LILE (K, Rb, Ba) and radionuclides (U, Th). On a smaller scale, however, there has been a mineralogically-controlled decoupling of various components, particularly among the HFSE and REE, the former favouring the phlogopite-rich outer layer of the reaction rim, the latter the amphibole-rich inner zone. Taken together, however, the reaction zones preserve key compositional features of their inferred protolith.

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