Petrological, mineralogical, isochronological data accumulated in the last 4 years are summarized. The variations of lithology and protolith. as well as block-in-matrix structure of UHP (uHrahigh-pressure) rocks imply...Petrological, mineralogical, isochronological data accumulated in the last 4 years are summarized. The variations of lithology and protolith. as well as block-in-matrix structure of UHP (uHrahigh-pressure) rocks imply a metamorphic melange. Clockwise P-T paths of UHP rocks indicate that their formation and exhumation are related to collisional orogeny. Isochronological data indicate that the peak UHP metamorphism was during the Middle-Late Triassic. The exhumation rates, estimated according to P-T-t paths, show a multiple exhumation stages, with a high exhumation rate (3.3-3.6 mm/a) in the Middle-Late Triassic, a lower rate (0.7-1.1 mm/a) in the Early Jurassic, and a very low rate (0.15 mm/a) in the Middle Jurassic to Early Cretaceous. With these constraints, a hypothetical cross-section of the Dabie orogenic belt is constructed.展开更多
A 0.2C-1.5Mn-1.5Si-0.6Cr-0.05Nb （wt%） steel is treated respectively by novel quenching-partitioning-tempering （Q-P-T） process and traditional quenching and tempering （Q＆T） process for comparison. X-ray diffract...A 0.2C-1.5Mn-1.5Si-0.6Cr-0.05Nb （wt%） steel is treated respectively by novel quenching-partitioning-tempering （Q-P-T） process and traditional quenching and tempering （Q＆T） process for comparison. X-ray diffraction analysis indicates that Q-P-T steel has about 10% retained austenite, but Q＆T steel hardly has one. With the increase of com- pression strain rate from 7 × 10^2 to 5 × 10^3 s^-1, the flow stress of Q-P-T steel increases, which demonstrates the positive strain rate effect, but does not exist in Q＆T steel. The characterization of scanning electron microscopy indicates that a large number of long, straight martensite laths in Q-P-T steel will bend or be destroyed by large compressive strain of 35% at 5 × 10^3 s^-1. However, relative small compressive s^xain of about 5% at 7× 10^2 s^-1 almost does not have any effect on the original lath morphology. The characterization of transmission electron microscopy further reveals the origin of the positive strain rate effect and the microstructural evolution during dynamic compressive deformation.展开更多
The eclogites from the Altyn Tagh, northwestern China have been subjected to medium-temperature and high-pressure metamorphism, and then overprinted by the amphibolite to granulite facies retrograde metamorphism, A co...The eclogites from the Altyn Tagh, northwestern China have been subjected to medium-temperature and high-pressure metamorphism, and then overprinted by the amphibolite to granulite facies retrograde metamorphism, A complex compositionai zoning was well preserved in the garnet porphyroblast formed during the metamorphism of eclogite facies. This zoning recorded P-T path of multistage metamorphism, and an early retrogressive process with features of decreasing pressure and increasing temperature. This evidences a short residence time for the eclogite at peak metamorphism and early retrogression, and thus rapid tectonic uplift history.展开更多
基金Project supported by the National Natural Science Foundation of China.
文摘Petrological, mineralogical, isochronological data accumulated in the last 4 years are summarized. The variations of lithology and protolith. as well as block-in-matrix structure of UHP (uHrahigh-pressure) rocks imply a metamorphic melange. Clockwise P-T paths of UHP rocks indicate that their formation and exhumation are related to collisional orogeny. Isochronological data indicate that the peak UHP metamorphism was during the Middle-Late Triassic. The exhumation rates, estimated according to P-T-t paths, show a multiple exhumation stages, with a high exhumation rate (3.3-3.6 mm/a) in the Middle-Late Triassic, a lower rate (0.7-1.1 mm/a) in the Early Jurassic, and a very low rate (0.15 mm/a) in the Middle Jurassic to Early Cretaceous. With these constraints, a hypothetical cross-section of the Dabie orogenic belt is constructed.
基金supported by the National Natural Science Foundation of China (Nos. 51031001 and 51371117)
文摘A 0.2C-1.5Mn-1.5Si-0.6Cr-0.05Nb （wt%） steel is treated respectively by novel quenching-partitioning-tempering （Q-P-T） process and traditional quenching and tempering （Q＆T） process for comparison. X-ray diffraction analysis indicates that Q-P-T steel has about 10% retained austenite, but Q＆T steel hardly has one. With the increase of com- pression strain rate from 7 × 10^2 to 5 × 10^3 s^-1, the flow stress of Q-P-T steel increases, which demonstrates the positive strain rate effect, but does not exist in Q＆T steel. The characterization of scanning electron microscopy indicates that a large number of long, straight martensite laths in Q-P-T steel will bend or be destroyed by large compressive strain of 35% at 5 × 10^3 s^-1. However, relative small compressive s^xain of about 5% at 7× 10^2 s^-1 almost does not have any effect on the original lath morphology. The characterization of transmission electron microscopy further reveals the origin of the positive strain rate effect and the microstructural evolution during dynamic compressive deformation.
文摘The eclogites from the Altyn Tagh, northwestern China have been subjected to medium-temperature and high-pressure metamorphism, and then overprinted by the amphibolite to granulite facies retrograde metamorphism, A complex compositionai zoning was well preserved in the garnet porphyroblast formed during the metamorphism of eclogite facies. This zoning recorded P-T path of multistage metamorphism, and an early retrogressive process with features of decreasing pressure and increasing temperature. This evidences a short residence time for the eclogite at peak metamorphism and early retrogression, and thus rapid tectonic uplift history.
