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The Maksyutov Complex consists of three fault-bounded lithologic units: a quartzofeldspathic gneiss containing mafic eclogite boudins (Unit #1); a metasedimentary blueschist-facies (Yumaguzinskaya) unit; and a meta-ophiolitic melange (Unit #2). The geologic history of the high- to ultrahigh-pressure (HP-UHP) assembly of the Maksyutov Complex is complicated by several stages of prolonged retrograde...
Abundant garnet-bearing granulite lenses are widely distributed in the northern part of the Sulu region and adjacent areas. They are possibly re-metamorphosed high-pressure metamorphic rocks. On the basis of detailed petrographic study, samples WD01, WD04 and ML06 from Laixi and Wendeng were identified as high-pressure granulites, and WH1 from Weihai as an original coesite-bearing eclogite. Three...
The Western Gneiss Region (WGR) marks the outcrop of a composite terrane consisting of variably re-worked Proterozoic basement and parautochthonous or autochthonous cover units. The WGR exhibits a gross structural, petrographic and thermobarometric zonation from southeast to northwest, reflecting an increasing intensity of Scandian (late Palaeozoic) metamorphic and structural imprint. Scandian-aged...
As is typical of ultra-high pressure (UHP) terrains, the regional extent of the UHP terrain in the Dabieshan of central China is highly speculative, since the volume of eclogites and paragneisses preserving unequivocal evidence of coesite and/or diamond stability is very small. By contrast, the common garnet (X Mn =0.18-0.45)-phengite (Si=3.2-3.35)-zoned epidote (Ps 38-...
Using relevant geothermobarometric methods, P-T-data were collected for the reconstruction of the metamorphic evolution of 34 eclogite samples taken from small lenses and boudins within the ultrahigh-pressure (UHP) metamorphic coesite-bearing Brossasco-Isasca Unit (BIU) of the Dora-Maira Massif. The mineral phases used (clinopyroxene, garnet, phengite), or growth zones thereof, were identified as...
Coarse-grained whiteschist, containing the assemblage: garnet+kyanite+phengite+talc+quartz/coesite, is an abundant constituent of the ultrahigh-pressure metamorphic (UHPM) belt in the Kulet region of the Kokchetav massif of Kazakhstan.Garnet displays prograde compositional zonation, with decreasing spessartine and increasing pyrope components, from core to rim. Cores were recrystallized at T=380 ...
The 558-m-deep ZK703 drillhole located near Donghai in the southern part of the Sulu ultrahigh-pressure metamorphic belt, eastern China, penetrates alternating layers of eclogites, gneisses, jadeite quartzites, garnet peridotites, phengite-quartz schists, and kyanite quartzites. The preservation of ultrahigh-pressure metamorphic minerals and their relics, together with the contact relationship and...
The Hong'an region in the Qinling-Dabie collisional zone in eastern China hosts a series of metamorphic rocks exposing a south-to-north distribution from blueschist/blueschist-greenschist, amphibolite, eclogite (kyanite free) and kyanite-eclogite to coesite-eclogite facies rocks that represent progressively deeper levels of the Mesozoic subduction-collision complex. The Hong'an area is interesting...
Coesite and omphacite inclusions have been identified for the first time as minute inclusions in zircon from amphibolite-facies granitic orthogneiss in the Sulu ultrahigh-pressure (UHP) metamorphic terrane of eastern China by Raman spectroscopy and microprobe analyses. The occurrences of these minerals in the voluminous granitic gneiss of Sulu support a regional and pervasive UHP metamorphic event...
Marbles from Dabieshan and Sulu, China, suffered ultra high pressure (UHP) metamorphism in the coesite-eclogite facies at approximately 700 o C and 30 kbars during Triassic continental collision and subduction. The marbles range in isotopic composition from +7 to +25 δ 18 O VSMOW and from 0 to +6 δ 13 C VPDB . High...
The stability and phase relations of phengitic muscovite in a metapelitic bulk composition containing a mixed H 2 O+CO 2 fluid were investigated at 6.5-11 GPa, 750-1050 o C in synthesis experiments performed in a multianvil apparatus. Starting material consisted of a natural calcareous metapelite from the coesite zone of the Dabie Mountains, China, ultrahigh-pressure metamorphic...
Granulitized coesite-bearing eclogite from Weihai, northeastern part of the Shandong peninsula, eastern China was studied in detail to reveal the modification of mineral chemistry during decompression metamorphism. Considerable modification of chemical composition is recorded in clinopyroxene that occurs both as inclusions in garnet and as a matrix mineral. Careful examination of chemical variation...
An unusual eclogite pod containing impure jadeite to omphacite pyroxene with anti-phase domain (APD) visible under the optical microscope is hosted in a medium-grade matrix in the Leaota Massif. Textural relationships support the hypothesis of garnet formation by peritectic reactions involving high-jadeite clinopyroxene, while inclusions entrapped in garnet, mainly a wide range of amphibole compositions,...
A transitional eclogite- to high-pressure granulite-facies paragenesis (Omp+Pl+Qtz+/-Grt) after peak coesite-eclogite facies metamorphism and predating the later amphibolite-facies overprint is identified in coesite-eclogite from the Taohang area of the Sulu ultrahigh-pressure (UHP) terrane in eastern China. These minerals were equilibrated at 17 kbar and 820 o C. This reveals that fluid infiltration...
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