Composition of barian mica in multiphase solid inclusions from orogenic garnet peridotites as evidence of mantle metasomatism in a subduction zone setting

2018 ◽  
Vol 173 (12) ◽  
Author(s):  
Renata Čopjaková ◽  
Jana Kotková
Keyword(s):  
Subduction Zone ◽  
Mantle Metasomatism

Experimental modeling of mantle metasomatism coupled with eclogitization of crustal material in a subduction zone

Petrology ◽  
2013 ◽  
Vol 21 (6) ◽  
pp. 579-598 ◽  
Author(s):  
A. L. Perchuk ◽  
M. Yu. Shur ◽  
V. O. Yapaskurt ◽  
S. T. Podgornova
Keyword(s):  
Subduction Zone ◽  
Mantle Metasomatism ◽  
Experimental Modeling ◽  
Crustal Material

scholarly journals Cr-spinel records metasomatism not petrogenesis of mantle rocks

2019 ◽  
Vol 10 (1) ◽  
Author(s):  
Hamed Gamal El Dien ◽  
Shoji Arai ◽  
Luc-Serge Doucet ◽  
Zheng-Xiang Li ◽  
Youngwoo Kil ◽  
...  
Keyword(s):  
Subduction Zone ◽  
Plate Tectonics ◽  
Mantle Metasomatism ◽  
Mantle Melting ◽  
Ultramafic Rocks ◽  
Chromian Spinel ◽  
Core Composition ◽  
Mid Ocean Ridge ◽  
Ocean Ridge ◽  
Petrogenetic Indicator

Abstract Mantle melts provide a window on processes related to global plate tectonics. The composition of chromian spinel (Cr-spinel) from mafic-ultramafic rocks has been widely used for tracing the geotectonic environments, the degree of mantle melting and the rate of mid-ocean ridge spreading. The assumption is that Cr-spinel’s core composition (Cr# = Cr/(Cr + Al)) is homogenous, insensitive to post-formation modification and therefore a robust petrogenetic indicator. However, we demonstrate that the composition of Cr-spinel can be modified by fluid/melt-rock interactions in both sub-arc and sub-mid oceanic mantle. Metasomatism can produce Al-Cr heterogeneity in Cr-spinel that lowers the Cr/Al ratio, and therefore modifies the Cr#, making Cr# ineffective as a geotectonic and mantle melting indicator. Our analysis also demonstrates that Cr-spinel is a potential sink for fluid-mobile elements, especially in subduction zone environments. The heterogeneity of Cr# in Cr-spinel can, therefore, be used as an excellent tracer for metasomatic processes.

Subduction-related Manipur Ophiolite Complex, Indo-Myanmar Ranges: elemental and isotopic record of mantle metasomatism

2019 ◽  
Vol 481 (1) ◽  
pp. 195-210 ◽  
Author(s):  
Oinam Kingson ◽  
Rajneesh Bhutani ◽  
S. Balakrishnan ◽  
J. K. Dash ◽  
Anil D. Shukla
Keyword(s):  
Subduction Zone ◽  
Isotope Ratios ◽  
Mantle Metasomatism ◽  
Ophiolite Complex ◽  
Rock Interaction ◽  
Nd Isotope ◽  
Mafic Rocks ◽  
Geochemical Variation ◽  
Manipur Ophiolite Complex ◽  
First Time

AbstractThis study reports, for the first time, Sr and Nd isotope ratios from the mafic rocks in the Manipur Ophiolite Complex (MOC), along with new elemental abundances to show the subduction zone influence. The initial 87Sr/86Sr ratios (for t = 127 Ma) range from 0.705230 to 0.709734. The initial 143Nd/144Nd and ɛNdt (t = 127 Ma) range from 0.512611 to 0.512900 and +2.7 to +8.3, respectively. The high field strength element (HFSE) ratios vary widely, with Nb/Ta ranging from c. 3 to 18 and Zr/Hf ranging from 20 to 41, indicating fluid–rock interaction in the presence of rutile. The correlated variation in the Nd and Sr isotope ratios and the HFSEs, including TiO2, reflects the variation in the slab-derived fluids. The light rare earth element (LREE) enriched and flat patterns yielded by the mafic rocks are modelled by varying the degree of melting of the fluid-metasomatized mantle. The subsequent influx of the slab-derived fluid at a greater depth caused the re-melting of the previously depleted wedge to produce the LREE-depleted patterns.We propose that the geochemical variation recorded in the MOC rocks indicates the changing nature of fluid metasomatism of the mantle wedge across the subduction zone with time.

Petrogenesis of the Harsin–Sahneh serpentinized peridotites along the Zagros suture zone, western Iran: new evidence for mantle metasomatism due to oceanic slab flux

2018 ◽  
Vol 156 (5) ◽  
pp. 772-800 ◽  
Author(s):  
FATEMEH NOURI ◽  
YOSHIHIRO ASAHARA ◽  
HOSSEIN AZIZI ◽  
MOTOHIRO TSUBOI
Keyword(s):  
Subduction Zone ◽  
Oceanic Lithosphere ◽  
Mantle Metasomatism ◽  
Suture Zone ◽  
Chemical Compositions ◽  
Oceanic Ridge ◽  
Tethys Realm ◽  
Reaction Processes ◽  
New Evidence ◽  
Light Rare Earth Elements

AbstractThe Harsin–Sahneh serpentinized peridotites are widely exposed along the Zagros suture zone in the western region of Iran and are considered to represent remnants of Neo-Tethys oceanic lithosphere at the junction of the Arabian and Iran Plates. These rocks are characterized by low contents of SiO2 (38.8–43.5 wt%), Al2O3 (0.1–3.8 wt%), CaO (0.2–8.2 wt%) and TiO2 (< 1 wt%) and high MgO contents (31.1–46.0 wt%). Their enrichments of large ion lithophile elements and light rare earth elements, with high 87Sr/86Sr(i) values (0.7036–0.7109) and relatively high variations in their εNd(t) (–7.5 to +7.8) values, indicate that the Harsin–Sahneh peridotites were metasomatized by flux released from the oceanic subducting slab in an active margin. The chemical compositions and isotopic ratios of these rocks suggest that they were formed as residue of mid-oceanic ridge basalt in the lithosphere that was then subsequently re-melted and metasomatized in a supra-subduction zone system. The occurrence of both mid-oceanic ridge and supra-subduction zone-type peridotites suggests that the heterogeneity of the upper mantle may have occurred due to the different ratios of partial melting and melt–rock reaction processes in different tectonic settings within the Neo-Tethys realm. The Harsin–Sahneh peridotites provide a good explanation of multistage melt extraction as well as melt–rock and metasomatic reactions in the mantle sequence of the Zagros ophiolite complex.

Sign in / Sign up

Export Citation Format

Share Document