نتایج جستجو برای: prograde metamorphism
تعداد نتایج: 2624 فیلتر نتایج به سال:
Metamorphic index mineral zones, pressure– temperature (P–T) conditions, and CO2–H2O fluid compositions were determined for metacarbonate layers within the Wepawaug Schist, Connecticut, USA. Peak metamorphic conditions were attained in the Acadian orogeny and increase from 420 C and 6.5 kb in the low-grade greenschist facies to 610 C and 9.5 kb in the amphibolite facies. The index minerals olig...
The Naghadeh metamorphic complex at the West-Azerbaijan Province is located at termination of the NW Sanandaj-Sirjan Zone. Major varieties of the metamorphic rocks in this area are: amphibolites, greenschists, marbles and metaperidotites. The metaperidotites are classified into two groups, serpentinised metaperidotites and serpentinites. Orthopyroxene, clinopyroxene, olivine and spinel are the ...
Lawsonite eclogites represent fossil records of processes occurring during subduction of cold and fast-subducting slabs, and provide the opportunity to investigate the thermal and metamorphic evolution of palaeosubduction zones. Occurrences of lawsonite eclogites are rare because lawsonite is often replaced during exhumation. We report here, for the first time, the occurrence of a lawsonite ecl...
The prograde metamorphism of eclogites is typically obscured by chemical equilibration at peak conditions and by partial requilibration during retrograde metamorphism. Eclogites from the Eastern Blue Ridge of North Carolina retain evidence of their prograde path in the form of inclusions preserved in garnet. These eclogites, from the vicinity of Bakersville, North Carolina, USA are primarily co...
kamtal skarn is located 15 km northeast of kharvana, east-azarbaijan. a quartz-monzonitic stock of oligocene age intruded the upper cretaceous sedimentary sequence (claystone, limestone, marl, and siltstone) developing noticeable metamorphic (marble, hornfels) and metasomatic (skarn) alteration zones along the contact. kamtal skarn is of calcic type and consists of both endoskarn and exoskarn z...
Ar–Ar and fission-track dating from four low-grade sections in the Alpujárride Complex sheds light on the timing of the early contractional history of these high-pressure metamorphic units, and their subsequent exhumation during the early Miocene extensional collapse of the Betic orogen. White mica grains from the lowest-grade rocks yield partly reset detrital Ar–Ar ages; where deformation and ...
In situ analysis reveals that eclogite-facies garnets are zoned in dO with lower values in the core and rims that are *1.5 to 2.5 % higher. This pattern is present in 9 out of 12 garnets analyzed by SIMS from four orogenic eclogite terranes, and correlates with an increase in the mole fraction of pyrope and Mg/Fe ratio from core to rim, indicating prograde garnet growth. At the maximum temperat...
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