Structural evolution of the Main Ural Fault Zone in the western framework of the Voikar-Synya ophiolite massif

Sychev, S. N.; Куликова, К. В.

doi:10.1134/s0016852112050056

Cited by 6 publications

(2 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Metamorphism reinforced metasomatic processes in the serpentinite melange, formation of a cryptocrystalline tangled-fibrous structure of nephrite, but then led to its fragmentation and replacement with omphacite. There are eight stages of the deformation process for the region [53], during which regressive and progressive regimes could replace each other.…”

Section: Discussionmentioning

confidence: 99%

Nyrdvomenshor Gem Stones Deposit, Polar Urals, Russia

Kislov¹,

Попов²,

Nurmukhametov³

et al. 2023

Preprint

View full text Add to dashboard Cite

We have studied quality characteristics, chemical, mineral and isotope composition of nephrite, diopsidite and rodingite of the Nyrdvomenshor deposit in the Polar Urals. We applied the visual petrographic and mineralogical studies, X-ray spectral fluorescence, ICP-MS analysis, scanning electron microscope with the dispersive microanalysis system, oxygen isotope composition was measured. According to its quality characteristics, the nephrite is substandard. Here, uvarovite, which forms idiomorphic grains, sometimes sheath-like, less often xenomorphic elongated, and substituting chromite are commonly encountered. The nephrite was formed due to both metamorphic and metasomatic processes. Serpentinite was replaced by diopsidite, which was then replaced by nephrite. Metamorphism intensified metasomatism of the serpentinite melange and provided a cryptocrystalline tangled-fibrous structure of the nephrite. Then metamorphism and metasomatism led to the formation of omphacite and cracking of the nephrite, which reduced its quality. As these processes progressed, contribution of crustal fluid increased.

show abstract

Section: Discussionmentioning

confidence: 99%

Nyrdvomenshor Gem Stones Deposit, Polar Urals, Russia

Kislov¹,

Попов²,

Nurmukhametov³

et al. 2023

Preprint

View full text Add to dashboard Cite

show abstract

“…the Marun‐Keu complex; Glodny et al., 2004; Meng et al., 2020; Udovkina, 1971). In the Polar Urals, the MUT exhibits a complex tectono‐metamorphic history encompassing a main prograde and a moderate retrograde structural overprint (Sichev & Kulikova, 2012). A recent finding reporting an occurrence of garnet peridotite showing peak burial conditions >3.5 GPa (Selyatitskii & Kulikova, 2017) in the Marun‐Keu complex contrasts with other estimates pointing to relatively shallower burial conditions (1.6–⁠2.1 GPa) in a rather hot subduction environment (600–⁠700°C; Liu et al., 2019; Molina et al., 2002).…”

Section: Geological Backgroundmentioning

confidence: 99%

Drainage of subduction interface fluids into the forearc mantle evidenced by a pristine jadeitite network (Polar Urals)

Glodny

Cambeses

Raimondo

et al. 2020

Journal Metamorphic Geology

View full text Add to dashboard Cite

The physical and mechanical processes rooted in the hydrated, serpentinized mantle above subduction zones remain insufficiently explored despite fundamental implications for our understanding of rheology and fluid recycling along subduction interfaces. Through a field-based investigation, serpentinized peridotites and jadeitite samples from a fossil forearc mantle in the Polar Urals (Russia) are studied here to document fluid-rock interaction processes in the high-P field, as well as the long-term evolution of the base of the mantle wedge. Petrographic, geochemical and microstructural observations reveal a complex, protracted evolution of the jadeitite-forming fluid pathway throughout the gradual cooling of the forearc mantle and increasing serpentinization of the host. It is shown that the jadeitite lenses in the studied locality (a) derive for a large part from a trondhjemitic dyke earlier emplaced in a warm subduction environment, and (b) record the cooling of the subduction hangingwall under high-P conditions associated with increasing host serpentinization. In the studied locality, the majority of the jadeitites formed at relatively high temperatures (>600°C) by the influx of Na-Al-rich, slab-derived metamorphic fluids that were drained along the base of the mantle wedge, parallel to the subduction interface. Changes in bulk-rock geochemical signatures and in paragenetic sequences also constrain the compositional evolution of the fluid channelized along this drainage, with an increasing sedimentary component. The phlogopite-bearing walls of the dyke exhibit Rb-Sr and Ar-Ar ages ranging between c. 405 and c. 390 Ma, a range partly overlapping within uncertainty with the previously dated zircons from the jadeitite core (410-400 Ma; U-Pb). This study opens a unique window on the pristine structures formed above the plate interface by melting and fluid-rock interaction in the early subduction stages, as well as their evolution during secular cooling of the base of the mantle wedge.

show abstract