scholarly journals The Molybdenum Isotope System as a Tracer of Slab Input in Subduction Zones: An Example From Martinique, Lesser Antilles Arc

2017 ◽  
Vol 18 (12) ◽  
pp. 4674-4689 ◽  
Author(s):  
Richard M. Gaschnig ◽  
Christopher T. Reinhard ◽  
Noah J. Planavsky ◽  
Xiangli Wang ◽  
Dan Asael ◽  
...  
Keyword(s):  
Subduction Zones ◽  
Lesser Antilles ◽  
Molybdenum Isotope ◽  
Isotope System ◽  
Lesser Antilles Arc

scholarly journals Tracing subducted black shales in the Lesser Antilles arc using molybdenum isotope ratios

Geology ◽  
2016 ◽  
Vol 44 (12) ◽  
pp. 987-990 ◽  
Author(s):  
Heye Freymuth ◽  
Tim Elliott ◽  
Matthijs van Soest ◽  
Susanne Skora
Keyword(s):  
Isotope Ratios ◽  
Black Shales ◽  
Lesser Antilles ◽  
Molybdenum Isotope ◽  
Lesser Antilles Arc

scholarly journals Isotopic Compositions of Plagioclase From Plutonic Xenoliths Reveal Crustal Assimilation Below Martinique, Lesser Antilles Arc

2021 ◽  
Vol 9 ◽  
Author(s):  
J. R. Brown ◽  
G. F. Cooper ◽  
G. M. Nowell ◽  
C. G. Macpherson ◽  
I. Neill ◽  
...  
Keyword(s):  
Subduction Zones ◽  
Lesser Antilles ◽  
Sr Isotope ◽  
Crustal Assimilation ◽  
Arc Magmas ◽  
Isotopic Compositions ◽  
Mantle Sources ◽  
Show Evidence ◽  
Sediment Addition ◽  
Lesser Antilles Arc

The chemical and isotopic compositions of volcanic arc lavas often show evidence for involvement of a sedimentary component during magma genesis. Determining where this sedimentary component is added to arc magmas is of vital importance for constraining the extent to which sediments and volatiles are recycled at subduction zones. Lavas from Martinique in the Lesser Antilles arc have wide ranging isotopic compositions extending to highly radiogenic values (e.g. 87/Sr/86Sr up to ∼0.710) that could, in principle, be explained by sediment addition to the mantle source or by crustal assimilation in the upper plate. We use Sr isotopic compositions of plagioclase from Martinique plutonic xenoliths to provide evidence supporting the crustal assimilation hypothesis. Plagioclase from plutonic xenoliths formed in the mid-crust (∼12 km) show a restricted range of unradiogenic Sr isotope ratios (87Sr/86Sr = 0.7041–0.7042) whereas plagioclase from upper crustal plutonic xenoliths (∼6 km) show greater intra-sample variation and more radiogenic Sr isotopic compositions up to 87Sr/86Sr = 0.7047. This trend is also observed in plutonic xenolith whole rock 87Sr/86Sr. Combined, these results indicate that the range of Sr isotope compositions becomes larger and more radiogenic in Martinique magmas as a result of sediment assimilation at shallow crustal levels. This is supported by Assimilation-Fractional Crystallization modeling, which shows that assimilation of chemically and isotopically heterogenous crustal sediments can produce the isotopic variation in Martinique plutonic xenoliths and lavas. Our results highlight the importance of constraining crustal contributions from the upper plate before using arc lava geochemistry to quantify sediment and volatile recycling at subduction zones and assessing potential heterogeneity of arc mantle sources.

scholarly journals Along‐Arc Heterogeneity in Local Seismicity across the Lesser Antilles Subduction Zone from a Dense Ocean‐Bottom Seismometer Network

2019 ◽  
Vol 91 (1) ◽  
pp. 237-247 ◽  
Author(s):  
Lidong Bie ◽  
Andreas Rietbrock ◽  
Stephen Hicks ◽  
Robert Allen ◽  
Jon Blundy ◽  
...  
Keyword(s):  
Subduction Zone ◽  
Subduction Zones ◽  
Lesser Antilles ◽  
Seismogenic Zone ◽  
Ocean Bottom ◽  
Ocean Bottom Seismometer ◽  
Plate Interface ◽  
Local Seismicity ◽  
Slow Spreading ◽  
Lesser Antilles Arc

Abstract The Lesser Antilles arc is only one of two subduction zones where slow‐spreading Atlantic lithosphere is consumed. Slow‐spreading may result in the Atlantic lithosphere being more pervasively and heterogeneously hydrated than fast‐spreading Pacific lithosphere, thus affecting the flux of fluids into the deep mantle. Understanding the distribution of seismicity can help unravel the effect of fluids on geodynamic and seismogenic processes. However, a detailed view of local seismicity across the whole Lesser Antilles subduction zone is lacking. Using a temporary ocean‐bottom seismic network we invert for hypocenters and 1D velocity model. A systematic search yields a 27 km thick crust, reflecting average arc and back‐arc structures. We find abundant intraslab seismicity beneath Martinique and Dominica, which may relate to the subducted Marathon and/or Mercurius Fracture Zones. Pervasive seismicity in the cold mantle wedge corner and thrust seismicity deep on the subducting plate interface suggest an unusually wide megathrust seismogenic zone reaching ∼65  km depth. Our results provide an excellent framework for future understanding of regional seismic hazard in eastern Caribbean and the volatile cycling beneath the Lesser Antilles arc.

Main issues of an evacuation in case of volcanic crisis: social stakes in Guadeloupe (Lesser Antilles Arc)

2014 ◽  
Vol 73 (3) ◽  
pp. 2127-2147 ◽  
Author(s):  
Marie Chenet ◽  
Delphine Grancher ◽  
Marie Redon
Keyword(s):  
Lesser Antilles ◽  
Lesser Antilles Arc
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