Ultrahigh-pressure metamorphism in western Tianshan, China: Part I. Evidence from inclusions of coesite pseudomorphs in garnet and from quartz exsolution lamellae in omphacite in eclogites

Tectonic evolution of the South Tianshan orogen and adjacent regions, NW China: geochemical and age constraints of granitoid rocks

“…UHP-conditions for some eclogites were reported and discussed (cf. Zhang et al 2002aZhang et al , b, 2003Zhang et al , 2005bKlemd 2003). Networks of eclogite-facies veins derived from the dehydration of blueschists are widely present in the HP-LT metamorphic terrane (Gao and Klemd 2001;Gao et al 2007;John et al 2008).…”

Coesite in the eclogite and schist of the Atantayi Valley, southwestern Tianshan, China

“…Eclogite and blueschist largely occur in lens to massive block sizes (with 0.1 m to100 m dimensions) and in places they are intercalated with schist. In southwestern Tianshan, the Atantayi Valley respresents the largest exposure location for HP metabasites, where both the HP and UHP eclogites were first reported in the region [5,10]. Numerous rock types are exposed along the river, including eclogite, blueschist and pelitic-felsic schist.…”

“…In the UHP field, the occurrence of coesite inclusions in garnet is of significance because it identifies the possible episodic growth of garnet, which may, combined with garnet isopleth thermobarometry, decipher the P-T trajectory of a specific UHP rock. The first reports of UHP metamorphism in the southwestern Tianshan instigated debate that has continued until the recent discovery of coeiste in the Habutengsu Valley of this orogenic belt [3][4][5][6][7][8]. However, until now, coesite had not been optically identified in the rocks of the Atantayi Valley, where the eclogites involved in the "UHP versus HP" controversy were sampled [5,9].…”

“…The first reports of UHP metamorphism in the southwestern Tianshan instigated debate that has continued until the recent discovery of coeiste in the Habutengsu Valley of this orogenic belt [3][4][5][6][7][8]. However, until now, coesite had not been optically identified in the rocks of the Atantayi Valley, where the eclogites involved in the "UHP versus HP" controversy were sampled [5,9]. Detailed investigations of UHP minerals such as coesite are critical for elaborating on the spatial distribution and evolutionary characteristics of the UHP belt in the southwestern Tianshan.…”

Seismic Hazard in Tien Shan: Basement Structure Control Over the Deformation Induced by Indo-Eurasia Collision

“…At this time, in the Permo-Triassic, this entire assemblage was also docked to the Siberian continent further north in present-day co-ordinates [Carroll et al, 1995;Levashova et al 2007] and together these amalgamated terranes formed one of the nuclei of the current Asian continent. This Palaeozoic collision-accretion produced two ophiolite-and UHP-rock bearing suture zones [Allen et al, 1992;Zhang et al, 1993;Gao et al, 1998;Zhang et al 2002a;2002b;Bazhenov et al, 2003;John et al, 2008]. During the various subduction and accretion episodes, the Tien Shan units were vastly intruded by granitoids [Solomovich & Trifonov, 2002;Mao et al, 2004;Konopelko et al, 2007;Solomovich, 2007;Pirajno et al, 2008;Van der Voo et al, 2006;Kröner et al, 2008].…”