scholarly journals Correlation of metabasic rocks from metamorphic soles of the Dinaridic and the Western Vardar zone ophiolites (Serbia): Three contrasting pressure-temperature-time paths

2012 ◽  
pp. 61-85
Author(s):  
Danica Sreckovic-Batocanin ◽  
Nada Vaskovic ◽  
Vesna Matovic ◽  
Violeta Gajic
Keyword(s):  
High Pressure ◽  
Tectonic Setting ◽  
Granulite Facies ◽  
Oceanic Lithosphere ◽  
Medium Temperature ◽  
Vardar Zone ◽  
High Pressure High Temperature ◽  
Pressure Medium ◽  
Compositional Variations ◽  
Temperature Time

The field, petrological-mineralogical, geochemical and geochronological data of the metamorphic sole rocks recorded beneath the Fruska Gora, Povlen (Tejici), Stolovi and Banjska ophiolites in the Western Vardar Zone (WVZ) and beneath the Zlatibor, Bistrica, Sjenicki Ozren and Brezovica ophiolites in the Dinaridic ophiolite belt (DOB) in Serbia are compared. The focus has been made on metabasic rocks formed in contact with the oceanic crust members: cumulate gabbro and basalts of SSZ-type with E-MORB and OIB-signature and more evolved tholeiitic basalts of MOR-affinity. Amphibole, the major phase formed from the mafic sole components, depending on pressure-temperature conditions exhibits compositional variations. According to mineral assemblages, estimated P-T conditions and ages, the potential P-T paths are given: high pressure - low temperature blueschist facies assemblage (7-9 kbar and ~400?C and <300-350?C and 4-8 kbar), recorded only in the metamorphic sole at the Fruska Gora (WVZ); high pressure - high temperature amphibolite to granulite facies (8-10 kbar and >700-850?C), recorded in both domains, the WVZ (Banjska) and the DOB (Bistrica, Sjenicki Ozren, Brezovica) and medium pressure - medium temperature amphibolite facies assemblages (~3.5-7 kbar and >350-650?C) recognized in the WZV (Tejici, Devovici) and the DOB (Zlatibor). The peak metamorphic conditions point to depths of the oceanic lithosphere detachment and its initial cooling at 10-30 km, but the ages and tectonic setting of ophiolites remain poorly constrained. The summarized data may be used as an important key in geodynamic evolution of the Mesozoic Tethyan ophiolites.

High-pressure medium-temperature metamorphism of semi-pelitic rocks in the Scotia Metamorphic Complex, Powell Island, South Orkney Islands, Antarctica

2019 ◽  
Vol 91 ◽  
pp. 8-26
Author(s):  
Rodrigo Vinagre da Costa ◽  
Renato de Moraes ◽  
Rudolph Allard Johannes Trouw ◽  
Luiz Sérgio Amarante Simões ◽  
Julio Cezar Mendes
Keyword(s):  
High Pressure ◽  
Metamorphic Complex ◽  
Medium Temperature ◽  
Orkney Islands ◽  
South Orkney Islands ◽  
Pressure Medium ◽  
Pelitic Rocks

Extensional exhumation of a high-pressure granulite terrane in Payer Land, Greenland Caledonides: structural, petrologic, and geochronologic evidence from metapelites

2002 ◽  
Vol 39 (8) ◽  
pp. 1169-1187 ◽  
Author(s):  
Jane A Gilotti ◽  
Synnøve Elvevold
Keyword(s):  
High Pressure ◽  
Granulite Facies ◽  
Crustal Thickening ◽  
Low Grade ◽  
Granulite Facies Metamorphism ◽  
High Pressure High Temperature ◽  
High Pressure Granulite ◽  
Two Samples ◽  
Facies Metamorphism ◽  
Southern Half

The Payer Land gneiss complex is unique among the mostly amphibolite-facies, mid-crustal gneiss complexes in the East Greenland Caledonides due to its well-preserved, regional high-pressure (HP) granulite-facies metamorphism. High-pressure – high-temperature (HP–HT) assemblages are recognized in mafic, ultramafic, granitic, and metasedimentary lithologies. Anatectic metapelites contain the assemblage garnet + kyanite + K-feldspar + antiperthite (exsolved ternary feldspar) + quartz ± biotite ± rutile and record approximately the same peak metamorphic conditions (pressure (P) = 1.4–1.5 GPa, temperature (T) = 800–850°C) as those of the neighboring mafic HP granulites. The HP granulite-facies metamorphism is Caledonian based on in situ U–Th–Pb electron microprobe dating of monazite from two samples of the aluminous paragneiss. The monazites are found along garnet–kyanite phase boundaries, as inclusions in garnet and kyanite, and within small leucocratic melt pods (K-feldspar + plagioclase + kyanite ± garnet) within the HP–HT paragneisses. Mylonitic equivalents of the metapelites contain a detrital monazite age signature that suggests the Payer Land paragneisses correlate with other Mesoproterozoic metasedimentary sequences in the area. The gneisses form a metamorphic core complex that is separated from the overlying low-grade sedimentary rocks of the Neoproterozoic Eleonore Bay Supergroup by an extensional detachment. This newly recognized Payer Land detachment is part of a system of prominent extensional faults located in the southern half of the Greenland Caledonides (i.e., south of 76°N). The HP granulites preserve the deepest level of crust exposed in this southern segment of the orogen and attest to significant crustal thickening.

scholarly journals High-pressure, high-temperature molecular doping of nanodiamond

2019 ◽  
Vol 5 (5) ◽  
pp. eaau6073 ◽  
Author(s):  
M. J. Crane ◽  
A. Petrone ◽  
R. A. Beck ◽  
M. B. Lim ◽  
X. Zhou ◽  
...  
Keyword(s):  
High Pressure ◽  
Ion Implantation ◽  
High Pressures ◽  
Noble Gas ◽  
Color Centers ◽  
Vacancy Defects ◽  
High Pressure High Temperature ◽  
Pressure Medium ◽  
Optical Pressure ◽  
Pressure Metrology

The development of color centers in diamond as the basis for emerging quantum technologies has been limited by the need for ion implantation to create the appropriate defects. We present a versatile method to dope diamond without ion implantation by synthesis of a doped amorphous carbon precursor and transformation at high temperatures and high pressures. To explore this bottom-up method for color center generation, we rationally create silicon vacancy defects in nanodiamond and investigate them for optical pressure metrology. In addition, we show that this process can generate noble gas defects within diamond from the typically inactive argon pressure medium, which may explain the hysteresis effects observed in other high-pressure experiments and the presence of noble gases in some meteoritic nanodiamonds. Our results illustrate a general method to produce color centers in diamond and may enable the controlled generation of designer defects.

scholarly journals Evidence for the Late Cretaceous Asteroussia event in the Gondwanan Ios basement terranes

2020 ◽  
Author(s):  
Sonia Yeung ◽  
Marnie Forster ◽  
Emmanuel Skourtsos ◽  
Gordon Lister
Keyword(s):  
High Pressure ◽  
Late Cretaceous ◽  
Metamorphic Core Complex ◽  
Metamorphic Event ◽  
Core Complex ◽  
Medium Temperature ◽  
Pressure Medium ◽  
Extreme Extension ◽  
The Individual ◽  
Metamorphic Core

Abstract. 40Ar/39Ar geochronology on garnet-mica schists and the underlying Gondwanan granitoid basement terrane on Ios demonstrates evidence of a Late Cretaceous high pressure, medium temperature (HP–MP) metamorphic event. This suggests that the Asteroussia crystalline nappe on Crete may extend northward and include Ios, in the Cyclades. If this is correct, the northern part of the Asteroussia nappe (on Ios) is overlain by the terrane stack defined by the individual slices of the Cycladic Eclogite-Blueschist Unit, whereas in the south (in Crete) the Asteroussia nappe is at the top of a nappe stack defined by the individual tectonic units of the external Hellenides. This geometry implies that the accretion of the Ios basement terrane involved a significant leap (250–300 km) southwards of the surface outcrop of the subduction megathrust. This accretion would have commenced at or about ~38 Ma, when the already exhumed terranes of the Cycladic Eclogite-Blueschist Unit had begun to thrust over the Ios basement. By ~35 Ma, we suggest the subduction jump had been accomplished, and renewed rollback began the extreme extension that led to the exhumation of the Ios metamorphic core complex.

Thermobarometry and geochronology of the Uvauk complex, a polymetamorphic Neoarchean and Paleoproterozoic segment of the Snowbird tectonic zone, Nunavut, Canada

2007 ◽  
Vol 44 (2) ◽  
pp. 245-266 ◽  
Author(s):  
A J Mills ◽  
R G Berman ◽  
W J Davis ◽  
S Tella ◽  
S Carr ◽  
...  
Keyword(s):  
High Pressure ◽  
Shear Zones ◽  
Granulite Facies ◽  
Crustal Thickening ◽  
High Grade ◽  
Retrograde Metamorphism ◽  
Tectonic Zone ◽  
History Of ◽  
Thermal Overprint ◽  
Temperature Time

The Uvauk complex is an ultramylonite-bounded, granulite-facies suite of anorthosite–gabbro that forms part of the Chesterfield Inlet segment of the Snowbird tectonic zone. Following initial anorthosite–gabbro magmatism at ca. 2.71 Ga and a cryptic 2.62–2.60 Ga event marked by zircon and monazite growth, the Uvauk complex experienced two high-grade tectonometamorphic events at 2.56–2.50 and 1.91–1.90 Ga. Similar to the 2.56–2.50 Ga development of other shear zones in the region, the upper-amphibolite-facies to granulite-facies, moderately high-pressure (8.4–11.0 kbar and 705–760 °C) (1 kbar = 100 MPA) M1 event is interpreted to have involved the structural emplacement of ca. 2.71 Ga Uvauk complex rocks on ca. 2.68 Ga tonalitic rocks to the south. Granulite-facies, high-pressure (11.2–14.7 kbar and 695–865 °C) M2 metamorphism, gabbroic magmatism, and mylonite development within the complex at ca. 1.9 Ga culminated with ~3.5 kbar decompression at high temperature. Clockwise pressure–temperature–time (P–T–t) paths reflect crustal thickening, thought to be related to the early accretionary history of the Trans-Hudson Orogen. A thermal overprint at ca. 1.85–1.75 Ga resulted in retrograde metamorphism (5.8–6.0 kbar and 625–695 °C) associated with post-tectonic granitoid plutonism.

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