Metamorphism and deformation of golpayegan metapelitic rocks, Sanandaj-Sirjan Zone, Iran
20
Citation
36
Reference
10
Related Paper
Citation Trend
Keywords:
Greenschist
Staurolite
Abstract Cretaceous (possibly older) metamorphic rock occurs mainly in the Blue Mountain inlier in eastern Jamaica. Fault‐bounded blocks reveal two styles of metamorphism, Westphalia Schist (upper amphibolite facies) and Mt. Hibernia Schist (blueschist (BS)–greenschist (GS) facies). Both Westphalia Schist and Mt. Hibernia Schist preserve detailed records of retrograde P–T paths. The paths are independent, but consistent with different parts of the type‐Sanbagawa metamorphic facies series in Japan. For each path, phase relationships and estimated P–T conditions support a two‐stage P–T history involving residence at depth, followed by rapid uplift and cooling. Conditions of residence vary depending on the level in a tectonic block. For the critical mineral reaction (isograd) in Westphalia Schist, conditions were P ∼7.5 kbars, T ∼600°C (upper amphibolite facies). Retrograde conditions in Hibernia Schist were P = 2.6–3.0 kbars, T = 219–237°C for a(H 2 O) = 0.8–1.0 (GS facies). Mt. Hibernia Schist may represent a volume of rock that was separated and uplifted at an early time from an otherwise protracted P–T path of the sort that produced the Westphalia Schist. Reset K–Ar ages for hornblende and biotite indicate only that retrograde metamorphism of Westphalia Schist took place prior to 76.5 Ma (pre‐Campanian). Uplift may have commenced with an Albian–Aptian (∼112 Ma) orogenic event. Copyright © 2008 John Wiley & Sons, Ltd.
Greenschist
Blueschist
Cite
Citations (7)
Abstract Petrological studies of staurolite–garnet–kyanite–biotite schist and garnet–muscovite schist of the Gula Complex, central Norway, provide constraints on metamorphic evolution during Scandian continent–continent collision, burial and exhumation of the Caledonian Upper Allochthon. The biotite schist contains conspicuous porphyroblasts of Fe-rich staurolite, garnet and kyanite, set in a fine-grained, well-foliated matrix of biotite, quartz, minor plagioclase and muscovite. The muscovite schist is fine- to medium-grained with a muscovite–quartz-dominated matrix, including garnet, biotite, minor plagioclase and clinozoisite. Pressure–temperature ( P – T ) modelling based on thermobarometric calculations and construction of P – T pseudo-sections illustrate that metamorphism reached 680 °C with pressures estimated up to 1.01±0.11 GPa. Retrogression and decompression are constrained by secondary mineral reactions: local replacement of kyanite to fibrous sillimanite indicates decompression below 0.7 GPa. Growth of foliation-parallel chlorite reflects cooling below 640 °C and the chlorite formation proceeded during cooling and decompression towards 550 °C and 0.4 GPa. The metamorphism is associated with a strong north–south-trending regional foliation, and retrogression and decompression apparently continued within the same strain regime. The P – T modelling shows that even small variations in whole-rock chemistry and P–T conditions can explain heterogeneity and significant shifts in mineralogy and modal concentration of the index minerals of metapelites.
Allochthon
Staurolite
Sillimanite
Cite
Citations (8)
Abstract Most of the tectonic, metamorphic and geochronological data suggest that the Himalaya is essentially the consequence of a single orogenic cycle associated with the India-Asia collision during the Cenozoic era. Therefore, metamorphic assemblages and tectonic structures across the Himalayan range are systematically considered as post-collisional geological records. However, over the last decades, several observations arguing for geological events predating the continental collision have become increasingly recurrent in the literature. Nevertheless, although some of these arguments are thoroughly documented, they are unduly ignored in the construction of models drawing the tectono-metamorphic evolution of the Himalayan range. Yet, the occurrence of a pre-Himalayan history would have considerable consequences on the classical models for the building of the Himalaya. The recent discovery of inclusions of staurolite crystals in greenschist facies garnets from the Miyar Valley in Upper Lahul region (Himachal Pradesh; NW India) revives the debate on the existence of a pre-Himalayan metamorphism. Indeed, the occurrence of high-temperature staurolites included in greenschist facies garnets suggests that the High Himalayan Crystalline rocks experienced an amphibolite facies metamorphism prior the predominant Himalayan greenschist facies metamorphism observed in this part of the range. In this study, phase petrology, microtectonic investigations combined with preexisting geochronological data infer that the crystallization of the included staurolite predates the growth of Himalayan garnets. These original data bring new arguments to bear on the long lasting debate of the existence of a Pre-Himalayan orogenic cycle. They lead to the conclusion that the growth of staurolite predates the continental collision between India and Asia and reflects a metamorphic event that belongs to a pre-Himalaya orogenic cycle.
Greenschist
Staurolite
continental collision
Diachronous
Orogeny
Cite
Citations (2)
The Taku Schist, which is located in the north-east Peninsular Malaysia, is characterized by its North-South oriented elongated body. It forms part of the Indonesian orogenic build-up that was generated via the convergence of the Sibumasu continental unit and Sukhothai Arc. Subsequent petrography analyses of the metasedimentary rocks sourced from the Taku Schist revealed that their formation was attributable to the metamorphism of greenschist into amphibolite facies, which could be observed near the Triassic and Cretaceous intrusions of the Kemahang Granite. The evolutionary process of the rocks could be linked with the interactions occurring between contact and regional metamorphisms. The resulting chemical classification upon their assessment disclosed that the metasedimentary rocks of Taku Schist were made up of greywacke and shale, grouped into the quartzose sedimentary provenance, and belonged to the Continental Island Arc (CIA). This information is required for the tectonic setting discrimination purpose. It is a reflection of the episodic contractions underwent by the Taku Schist, wherein they would lead to the Sibumasu sedimentary cover along with both an accretionary wedge and the genetically-correlated Bentong-Raub melange to different greenschist. Otherwise associated with amphibolite facies, the conditions and depths of the facies were determined according to their position in relation to the upper plate of the Sukhothai Arc.
Greenschist
Cite
Citations (3)
Investigated area is located in the Gordes submassif of the Menderes massif, the metamorphic basement consists of the fol- lowing lithologics in ascending order: Sillimanite-gamet gneiss. sillimanite-gamel-kyanitc schist. sillimanite-staurolite-gamet-kyanite schist, staurolite-garnet schist and garnet mica schist. Kyanite-andalusite pegmatoids which occur within the kyanite-bearing schists were formed in the course of the last major metamorphism giving the final stage to the Menderes massif. The metamorphic basement is overlain by the al- lochthonous units which are relicts of the Lycian nappes which caused the last major metamorphism during the Eocene-Oligocene time in Menderes massif. The age of the apatite crystals obtained from the pegmatoids arc determined by the fission-track method. The cooling age of the apatite crystals ranging from the Early Oligocene to Early Miocene are in good agreement with the field observations in the study area and geological evidences relating to the Menderes massif.
Sillimanite
Massif
Staurolite
Andalusite
Cite
Citations (0)
Greenschist
Staurolite
Cite
Citations (20)
Staurolite
Sillimanite
Greenschist
Cordierite
Isograd
Muscovite
Andalusite
Hornfels
Phyllite
Pelite
Cite
Citations (2)
Staurolite
Cite
Citations (69)
Pelitic schists from The Pütürge metamorphites contain important minerals, such as garnet, biotite, chlorite, kyanite, and staurolite which are used in the determination of degree of metamorphism. Kyanite in metapelites such as staurolite mica schist, stavrolite garnet mica schist, biotite schist and amphibole schist. Kyanite is one from AESiO5 polymorphs (andalusite, sillimanite and kyanite). Kyanite is approximately ten percent more dense than the other two, and hence formation of kyanite is favoured by high pressures. The metamorphic petrology uses pressure-temperature conditions during metamorphic events and fluids in metamorphic environment. The geobarometers were used to estimate metamorphic conditions of pelitic schistes in metamorphites. The study of garnet-aluminum silicate-plagioclase-quartz (GASP) barometry has a long history. Compositions of staurolite and garnet in the assemblage in samples were calculated from temperature and pressure changes. The calculated temperatures could be due to conditions of Ph2o < Ptotal during metamorphism. The equilibrium among staurolite, garnet, quartz and aluminum silicate is only approximately located in pressure-temperature space.
Staurolite
Andalusite
Isograd
Muscovite
Sillimanite
Pelite
Cite
Citations (0)