Water Content and Deformation of the Lower Crust Beneath the Siberian Craton: Evidence from Granulite Xenoliths

2021 ◽  
Author(s):  
Tianlong Jin ◽  
Qin Wang ◽  
Vladislav Shatsky ◽  
Yue Liao
Keyword(s):  
Water Content ◽  
Siberian Craton ◽  
Lower Crust ◽  
Granulite Xenoliths

Water Content, Deformation and Seismic Properties of the Lower Crust Beneath the Siberian Craton: Evidence from Granulite Xenoliths

2020 ◽  
Author(s):  
Qin Wang ◽  
Tianlong Jin ◽  
Vladislav Shatsky
Keyword(s):  
Water Content ◽  
Siberian Craton ◽  
Lower Crust ◽  
Seismic Anisotropy ◽  
Bulk Water ◽  
Crust And Upper Mantle ◽  
Equilibrium Pressure ◽  
Mechanical Coupling ◽  
Granulite Xenoliths ◽  
Water Contents

<p>Although the continental lower crust is often assumed to be dry and strong, water in nominally anhydrous minerals can significantly decrease viscosity of granulites and affect the mechanical coupling between the crust and upper mantle. Here we measured water content and fabrics of 16 granulite xenoliths from the Udachnaya and Komsomolskaya kimberlites in the central Siberian craton, which were erupted in the Late Silurian. The equilibrium pressure and temperature of the granulite samples are in the range of 0.9–1.3 GPa and 683–822 ºC. The mean water contents in clinopyroxene, garnet and plagioclase are 744±272 ppm, 100±64 ppm, 423±245 ppm, respectively, suggesting the water-rich lower crust. The bulk water contents in granulites are independent on pressure and composition, but show a negative correlation with temperature. Compared with previous studies on granulite xenoliths and terrane granulites, our granulite samples have much higher bulk water contents. The lattice-preferred orientation of clinopyroxene is characterized by activation of the dominant slip system (100)[001], whereas garnet is randomly orientated. Plagioclase developed two dominant slip systems (001)[010] and (001)[100]. Calculated seismic anisotropy indicates that the weak fabric strength of these granulite samples will result in weak seismic anisotropy of the lower crust beneath the Siberian craton. We propose that during eruption of the kimberlite pipes in the Late Silurian, the lower crust of the Siberian craton, at least beneath the kimberlite fields, had high water contents, relatively low strength, weak seismic anisotropy, and high electrical conductivity. Such status may be representative for the lower crust beneath a stable craton. The following Siberian Traps in the end of Permian was associated with the magma underplating, which probably dehydrated and strengthened the lower crust of the Siberian carton.</p>

scholarly journals Fluid-Rock Interaction in the Lower Crust Based on Silicate Melt Inclusions in Garnet Granulite Xenoliths

2020 ◽  
Author(s):  
Bianca Németh ◽  
Kálmán Török ◽  
Eniko Bali ◽  
Zoltan Zajacz ◽  
Csaba Szabó
Keyword(s):  
Lower Crust ◽  
Melt Inclusions ◽  
Silicate Melt ◽  
Rock Interaction ◽  
Garnet Granulite ◽  
Granulite Xenoliths

scholarly journals New evidence for upper Permian crustal growth below Eifel, Germany, from mafic granulite xenoliths

2021 ◽  
Vol 33 (2) ◽  
pp. 233-247
Author(s):  
Cliff S. J. Shaw
Keyword(s):  
Rare Earth ◽  
Lower Crust ◽  
Volcanic Field ◽  
Upper Permian ◽  
Primitive Mantle ◽  
Magmatic Temperature ◽  
Heavy Rare Earth Elements ◽  
History Of ◽  
Granulite Xenoliths ◽  
West Eifel

Abstract. Granulite xenoliths from the Quaternary West Eifel Volcanic Field in Germany record evidence of magmatism in the lower crust at the end of the Permian. The xenoliths sampled two distinct bodies: an older intrusion (ca. 264 Myr old) that contains clinopyroxene with flat, chondrite-normalised rare earth element (REE) profiles and a younger (ca. 253 Myr old) intrusion that crystallised middle-REE-rich clinopyroxene. The younger body is also distinguished based on the negative Sr, Zr and Ti anomalies in primitive mantle-normalised multi-element plots. REE-in-plagioclase–clinopyroxene thermometry records the magmatic temperature of the xenoliths (1100–1300 ∘C), whereas Mg-in-plagioclase and Zr-in-titanite thermometry preserve an equilibration temperature of ca. 800 ∘C. These temperatures, together with a model of the mineral assemblages predicted from the composition of one of the xenoliths, define the pressure of crystallisation as ∼1 GPa. The xenoliths also preserve a long history of reheating events whose age ranges from 220 to 6 Myr. The last of these events presumably led to breakdown of garnet; formation of symplectites of orthopyroxene, plagioclase and hercynite; and redistribution of heavy rare earth elements into clinopyroxene. The data from the West Eifel granulite xenoliths, when combined with the existing data from granulites sampled in the East Eifel, indicate that the lower crust has a long a complex history stretching from at least 1.6 Ga with intrusive events at ca. 410 and 260 Ma and reheating from the Triassic to late Miocene.

scholarly journals A Reconnaissance Study of Ti-minerals in Cratonic Granulite Xenoliths and their Potential as Recorders of Lower Crust Formation and Evolution

2017 ◽  
Vol 58 (10) ◽  
pp. 2007-2034 ◽  
Author(s):  
Bibiana Förster ◽  
Sonja Aulbach ◽  
Cristen Symes ◽  
Axel Gerdes ◽  
Heidi E Höfer ◽  
...  
Keyword(s):  
Lower Crust ◽  
Crust Formation ◽  
Formation And Evolution ◽  
Granulite Xenoliths

Granulite xenoliths and their zircons, Tuoyun, NW China: Insights into southwestern Tianshan lower crust

2006 ◽  
Vol 145 (3-4) ◽  
pp. 159-181 ◽  
Author(s):  
J ZHENG ◽  
W GRIFFIN ◽  
S OREILLY ◽  
M ZHANG ◽  
J LIOU ◽  
...  
Keyword(s):  
Lower Crust ◽  
Nw China ◽  
Southwestern Tianshan ◽  
Granulite Xenoliths

scholarly journals SEISMIC STRUCTURE OF THE CRUST IN THE COLLISION ZONE BETWEEN SIBERIAN CRATON AND VERHOYANO- KOLYMA FOLDED SYSTEM (3-DV PROFILE)

2019 ◽  
Vol 2 (2) ◽  
pp. 180-186
Author(s):  
Vladimir Suvorov ◽  
Elena Melnik
Keyword(s):  
Siberian Craton ◽  
Lower Crust ◽  
High Speed ◽  
Seismic Structure ◽  
Upper Crust ◽  
Magmatic Origin ◽  
Collision Zone

The signs of the collisional structure are expressed in the upper crust by the advanced Priverhoyansk forland and local hinterland basins is separated by a high-speed array, most likely of magmatic origin. The boundary of the craton at an angle of about 15 ° is submerged under the crust of the folded system, where the characteristic layer of the craton lower crust at velocity of 6,7–6,9 km /s is absent and the velocity in a whole crust is reduced, as well as along the Moho from 8,3 to 7,9-8,0 km / s.

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