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A combined study of mineral inclusions, U–Pb ages and trace elements was carried for zircon and coexisting minerals from granulite in the North Dabie Terrane (NDT) of the Dabie–Sulu ultrahigh-pressure metamorphic (UHP) zone, east-central China. The results provide insights into the exhumation history of NDT and into rare earth element (REE) behavior during retrogression. Besides inherited cores and...
Relict magmatic titanite was identified in the core of a few titanite grains with the overgrown rim of metamorphic titanite in UHP metagranite in the Dabie orogen. LA–ICPMS U–Pb dating gave Neoproterozoic ages for the magmatic titanite but Triassic ages for the metamorphic titanite. The magmatic and metamorphic titanites are clearly distinct by differences in petrological and geochemical compositions...
LA-(MC)-ICPMS trace element, U–Pb and Hf isotope analyses were performed on zircons from continental-derived retrograde high-pressure metamorphic rocks, which were attested by the occurrence of HP mineral inclusions in metamorphic zircons, from the Huwan shear zone in the western Dabie orogen. Zircons in a schist sample are mostly detrital and gave U–Pb ages from 1212 to 2312Ma, suggesting that the...
Postcollisional mafic to felsic dykes in the western part of the Sulu orogen consist of monzogranite, diorite, plagioclase-bearing hornblendite and gabbro. LA-ICPMS zircon U–Pb dating yielded broadly consistent ages of 111±3 to 129±1Ma for their crystallization, with Neoproterozoic ages of 743±9 to 773±9Ma for residual cores. The mafic to felsic dykes are characterized by the arc-like patterns of...
A petrological study is carried out for a high-pressure (HP) omphacite–epidote vein and its host ultrahigh-pressure (UHP) eclogites at Ganghe in the Dabie orogen. The UHP eclogite shows systematic changes toward the HP vein in mineral assemblage, mineral proportion and bulk-rock composition. The eclogite far away from the vein (>20cm) contains abundant lawsonite pseudomorphs indicated by the aggregates...
A combined study of zircon U–Pb ages and Lu–Hf isotopes, whole-rock elements and Sr–Nd isotopes was carried out for two granitic intrusions at Changawuzi and Alasan in Muzhaerte River of Southwest Tianshan (NW China). SHRIMP zircon U–Pb dating gave two 206 Pb/ 238 U ages of 333±3Ma and 326±3Ma for the Changawuzi pluton. LA-ICP-MS zircon U–Pb dating yielded two 206 Pb/ 238...
Formation and exhumation of high-pressure (HP) to ultrahigh-pressure (UHP) metamorphic rocks in continental subduction zones are the two fundamental geodynamic aspects of collisional orogensis. This volume is based on the Session 08c titled “Geochemical processes in continental collision zones” at Goldschmidt 2010 in Knoxville, USA. It focuses on micro- to macro-scale processes that are temporally...
Petrography, mineral chemistry and pressure–temperature (P–T) estimates were carried out for the eclogite from the South Altyn in NW China. The results suggest three stages of metamorphism: an ultra-high pressure (UHP) eclogite-facies metamorphism at 717–871°C and ≥2.8GPa, a high pressure (HP) granulite-facies metamorphism at 624–789°C and 1.42–1.52GPa, and an amphibolite-facies metamorphism at 597–728°C...
Although petrologic data from the North Qinling orogen in central China have provided essential information on the geodynamic history of the orogenic cycle, the timing of the continental collision between the North China block and the South China block in the North Qinling orogen remains essentially unconstrained. To refine existing geodynamic models, two eclogites from the North Qinling were dated...
A petrological study was carried out for high pressure (HP) veins which cut through the host coesite-bearing eclogites at Habutengsu–Kebuerte in western Tianshan, China. The results place constraints on the origin and property of metamorphic fluids during subduction-zone metamorphism. Omphacite-, clinozoisite- and quartz-dominated veins occur on centimeter to meter scales within lens-shaped and layered...
A combined study of major and trace elements in garnet was carried out for low-T/UHP metagranite in the Dabie orogen. The results show different fashions of element zoning in the garnet, suggesting occurrence of both metamorphic and metamorphosed garnets. Three generations of garnet growth are distinguished on the basis of the assumption that Ca contents, Mn contents and Fe/Mg ratios of garnet in...
In-situ SIMS analyses of O and U–Pb isotopes as well as LA-(MC)-ICPMS analyses of trace elements, U–Pb, and Lu–Hf isotopes were carried out for zircon from a quartz vein and its host UHP eclogite in the Dabie orogen. The results are integrated to decipher the effect of aqueous fluid on the new growth of metamorphic zircon and on the recrystallization of protolith zircon during continental subduction-zone...
Spatial variations in whole-rock Sr–Nd–Pb isotopic compositions were investigated for Early Cretaceous mafic igneous rocks from western Shandong in the southeastern edge of the North China Block (NCB). The results are used to constrain the spatial extent of the influence of the deeply subducted South China Block (SCB) on the collided NCB. Five localities of mafic rocks were analyzed in this study,...
In-situ electron microprobe (EMP) U–Th–Pb monazite-, sensitive high-resolution ion microprobe (SHRIMP) zircon analyses, metamorphic phase equilibrium (Domino/Theriak)- and geothermobarometric calculations are performed on kyanite/sillimanite-bearing garnet biotite gneisses forming part of the dominant rock association in the Xitieshan ultra-high pressure metamorphic belt, north Qaidam, western China...
The Neoproterozoic Haizhou Group crops out sporadically in the Sulu orogen in east-central China. It is divided into the Jinping and Yuntai formations and consists of quartzite, quartz schist, marble and graphite- and apatite-bearing sequences. Major and trace element data for quartz schist from the two formations indicate that these rocks have a greywacke protolith and have been deposited during...
Felsic veins within the Xitieshan UHP eclogite in North Qaidam, NW China vary from 1cm or less to several decimetres in width, exhibiting coarse granular in texture and heterogeneous distribution in mineral assemblages. They encircle or cut the deformed sub-lentoid eclogite body. Some fine veins extended into and ended in the eclogite, without visible link to their country rocks. They consist mainly...
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