Four distinct litho-tectonic belts (zones) in the Yinshan area, North China, were identified by pressure-temperature contours and litho-tectonic features, such as the Sanggan granulite belt, Jining metasedimentary bel...Four distinct litho-tectonic belts (zones) in the Yinshan area, North China, were identified by pressure-temperature contours and litho-tectonic features, such as the Sanggan granulite belt, Jining metasedimentary belt, Wulashan-Daqingshan front tectonic zone and Se' eratengshan belt. This area witnessed two important thermo-tectonic events. The older one is c. 2.5 Ga while the younger one c. 1.9 Ga. The Se' ertengshan Neoarchaean terrane features a clockwise PT path with the decompression ranging from > 1500 MPa to 800–1000 MPa in the Se' ertengshan belt, which implies an island arc setting. The Sanggan belt is a Mesoarchaean microcontinent reworked by Neoarchaean magma underplating, which shows an counterclockwise PT path. During the Palaeoproterozoic period, two Archaean continent (arc) collided. The Archaean basement of the Sanggan and Wulashan-Daqingshan belts overthrust northwards, the PTt paths of basement show a decompression from 1000–1200 MPa to 500–700 MPa. The PT paths of the Jining and Erdaowa Groups show different PTt paths: the former shows counterclockwise while the latter clockwise, which indicates that the Jining and Erdaowa groups formed in different thermo-tectonic settings.展开更多
Airborne navigation database(NavDB)coding directly affects the result of analysis on the instrument flight procedure by the modern aircraft flight management computer(FMC).A reasonable flight track transition mode can...Airborne navigation database(NavDB)coding directly affects the result of analysis on the instrument flight procedure by the modern aircraft flight management computer(FMC).A reasonable flight track transition mode can improve the track tracking accuracy and flight quality of the aircraft.According to the path terminator(PT)and track transition characteristics of the performance based navigation(PBN)instrument flight procedure and by use of the world geodetic system(WGS)-84 ellipsoidal coordinate system,the algorithms for“fly by”and“fly over”track transition connections are developed,together with the algorithms for coordinates of fix-to-altitude(FA)altitude termination point and heading-to-an-intercept(VI)track entry point and for track transition display of the navigation display(ND).According to the simulation carried out based on the PBN instrument approach procedure coding of a certain airport and the PBN route data at a high altitude,the algorithm results are consistent with the FMC-calculated results and the actual ND results.展开更多
The high-pressure （HP） eclogite in the western Dabie Mountain encloses numerous hornblendes, mostly barroisite. Opinions on the peak metamorphic P-T condition, PT path and mineral paragenesis of it are still in disp...The high-pressure （HP） eclogite in the western Dabie Mountain encloses numerous hornblendes, mostly barroisite. Opinions on the peak metamorphic P-T condition, PT path and mineral paragenesis of it are still in dispute. Generally, HP eclogite involves garnet, omphacite, hornblendes and quartz, with or without glaucophane, zoisite and phengite. The garnet has compositional zoning with XMg increase, XCa and XMn decrease from core to rim, which indicates a progressive metamorphism. The phase equilibria of the HP eclogite modeled by the P-T pseudosection method developed recently showed the following： （1） the growth zonation of garnet records a progressive metamorphic PT path from pre-peak condition of 1.9-2.1 GPa at 508~C-514~C to a peak one of 2.3-2.5 GPa at 528~C-531~C for the HP eclogite; （2） the peak mineral assemblage is garnet＋omphacite＋glaucophane＋quartz_＋phengite, likely paragenetic with lawsonite; （3） the extensive hornblendes derive mainly from glaucophane, partial omphacite and even a little garnet due to the decompression with some heating during the post-peak stage, mostly representing the conditions of about 1.4-1.6 GPa and 580~C-640~C, and their growth is favored by the dehydration of lawsonite into zoisite or epidote, but most of the garnet, omphacite or phengite in the HP eclogite still preserve their compositions at peak condition, and they are not obviously equilibrious with the hornblendes.展开更多
Eclogites have been recently discovered in the Xitieshan area in the middlesegment of the northern margin of the Qaidam basin. These eclogites, together with those recognizedearlier in the Yuka area of the western seg...Eclogites have been recently discovered in the Xitieshan area in the middlesegment of the northern margin of the Qaidam basin. These eclogites, together with those recognizedearlier in the Yuka area of the western segment of the northern margin of the Qaidam basin and inthe Dulan area of the eastern segment of the northern margin of the Qaidam basin, form an eclogitebelt with a length of 350 km. A comparison of the eclogites from the Yuka and Xitieshan areassuggests that they show different country rocks, microtextures, mineral assemblages, and especially,different peak temperatures, PT paths during decompression and isotopic features. Eclogites fromthe Yuka area bear evidence of prograde metamorphism, such as prograde mineral relics in garnet andgrowth zoning of garnet, and hairpin-shaped PT paths with coincidence of the baric and thermal peaksof metamorphism, which reflect rapid burial and uplift. Sm-Nd isotopic determination shows obviousSm-Nd disequilibrium, and no isochron ages of Early Paleozoic metamorphism was obtained. On thecontrary, the Xitieshan eclogite was subjected to metamorphism of higher eclogite-facies andpost-eclogite-facies temperatures, showing an obvious granulite-facies overprint. A tentative PTpath for the Xitieshan area suggests that the baric peak preceded the thermal culmination. Wholerock-garnet-omphacite Sm-Nd isotopic data give an isochron age in the Early Paleozoic. Thedifferences between the two eclogites imply their different tectonic-thermal history during theirburial and uplift.展开更多
The Dabie orogen, Eastern Qinling orogen and Eastern Kunlun orogen are the major components of the Central Mountain Ranges of China and each has distinctively metamorphic processes in their oldest rock units. The Dab...The Dabie orogen, Eastern Qinling orogen and Eastern Kunlun orogen are the major components of the Central Mountain Ranges of China and each has distinctively metamorphic processes in their oldest rock units. The Dabie orogen oldest rock units had experienced an intermediate-higher pressure, upper amphibolite to lower granulite facies metamorphism in the Indosinian intracontinental subduction collision event. The clockwise pt path, synchronous attainment of t max and p max and a segment of high slope retrograde path suggest a tectono driven rapid exhumation of the oldest rock units to upper middle crustal level following the end of the subduction collision process. The oldest rock units, also called Qinling Group, of Eastern Qinling Mountains suffered intensively collisional metamorphism at an immature plate tectonic framework during Jinningian movement about 1 000 Ma ago. The clockwise pt path with reach of t max following several hundreds of MPa decreasing from p max suggests that the denudation of the deeply burial rock units was due essentially to isostatic relaxation. During the Caledonian stage, the highly metamorphosed oldest rock units suffered from a high t thermal event in arc environment and superimposed by contact metamorphism. After thermal peaks, the rock units were exhumed in a short distance and cooled down isobarically. No regional metamorphism higher than upper greenschist facies condition since 300 Ma has been traced within exposed rocks in the eastern portion of Northern Qinling orogen. The oldest rock units in the Eastern Kunlun orogen were metamorphosed to upper amphibolite facies to lower granulite facies rocks early or during the Luliang movement (some 1 800 Ma ago). The high grade metamorphic rock units had a long resident time at the deep crustal level, and were exhumed to middle upper crustal level during the Caledonian to Hercynian tectonometamorphic events. Shallow erosion of the orogenic belt led to good preservation of the low pressure metamorphic belt.展开更多
According to the field occurrences and petrological study, the low temperature eclogite facies metamorphic rocks in Western Tianshan of Xinjiang can be divided into five types: (i) massive glaucophane-epidote eclogite...According to the field occurrences and petrological study, the low temperature eclogite facies metamorphic rocks in Western Tianshan of Xinjiang can be divided into five types: (i) massive glaucophane-epidote eclogites and glaucophane-paragonite eclogites; (ii) schistose or gneissic mica eclogites; (iii) banded calcite eclogites; (iv) pillow glaucophane eclogites; (v) garnet-omphacite quartzites. Their eclogite facies metamorphism has undergone four stages of evolution: (i) pre-peak lawsonite-blueschist facies stage,T = 350–4000°C,P = 0.7–0.9 GPa; (ii) peak eclogite facies stage,T = 530 ± 20°C,P = 1.6–1.9 GPa; (iii) retrograde epidote-blueschist facies stage, T=500–530°C,P = 0.9–1.2 GPa and (iv) retrograde blueschist-greenschist facies stage,T= 450–550°C,P= 0.7–0.8 GPa. The metamorphic PT path of Western Tianshan eclogites is characterized by clockwise ITD resulting from the subduction of Tarim plate northward to Yili-Central Tianshan plate followed by fast uplift to the surface. But there were at least two stages of blueschist facies retrograde metamorphism overprinted during their uplift.展开更多
文摘Four distinct litho-tectonic belts (zones) in the Yinshan area, North China, were identified by pressure-temperature contours and litho-tectonic features, such as the Sanggan granulite belt, Jining metasedimentary belt, Wulashan-Daqingshan front tectonic zone and Se' eratengshan belt. This area witnessed two important thermo-tectonic events. The older one is c. 2.5 Ga while the younger one c. 1.9 Ga. The Se' ertengshan Neoarchaean terrane features a clockwise PT path with the decompression ranging from > 1500 MPa to 800–1000 MPa in the Se' ertengshan belt, which implies an island arc setting. The Sanggan belt is a Mesoarchaean microcontinent reworked by Neoarchaean magma underplating, which shows an counterclockwise PT path. During the Palaeoproterozoic period, two Archaean continent (arc) collided. The Archaean basement of the Sanggan and Wulashan-Daqingshan belts overthrust northwards, the PTt paths of basement show a decompression from 1000–1200 MPa to 500–700 MPa. The PT paths of the Jining and Erdaowa Groups show different PTt paths: the former shows counterclockwise while the latter clockwise, which indicates that the Jining and Erdaowa groups formed in different thermo-tectonic settings.
基金supported by the National Natural Science Foundation of China(u2133209)。
文摘Airborne navigation database(NavDB)coding directly affects the result of analysis on the instrument flight procedure by the modern aircraft flight management computer(FMC).A reasonable flight track transition mode can improve the track tracking accuracy and flight quality of the aircraft.According to the path terminator(PT)and track transition characteristics of the performance based navigation(PBN)instrument flight procedure and by use of the world geodetic system(WGS)-84 ellipsoidal coordinate system,the algorithms for“fly by”and“fly over”track transition connections are developed,together with the algorithms for coordinates of fix-to-altitude(FA)altitude termination point and heading-to-an-intercept(VI)track entry point and for track transition display of the navigation display(ND).According to the simulation carried out based on the PBN instrument approach procedure coding of a certain airport and the PBN route data at a high altitude,the algorithm results are consistent with the FMC-calculated results and the actual ND results.
基金funded by the National Natural Science Foundation of China (No.40525006 and 40372032).
文摘The high-pressure （HP） eclogite in the western Dabie Mountain encloses numerous hornblendes, mostly barroisite. Opinions on the peak metamorphic P-T condition, PT path and mineral paragenesis of it are still in dispute. Generally, HP eclogite involves garnet, omphacite, hornblendes and quartz, with or without glaucophane, zoisite and phengite. The garnet has compositional zoning with XMg increase, XCa and XMn decrease from core to rim, which indicates a progressive metamorphism. The phase equilibria of the HP eclogite modeled by the P-T pseudosection method developed recently showed the following： （1） the growth zonation of garnet records a progressive metamorphic PT path from pre-peak condition of 1.9-2.1 GPa at 508~C-514~C to a peak one of 2.3-2.5 GPa at 528~C-531~C for the HP eclogite; （2） the peak mineral assemblage is garnet＋omphacite＋glaucophane＋quartz_＋phengite, likely paragenetic with lawsonite; （3） the extensive hornblendes derive mainly from glaucophane, partial omphacite and even a little garnet due to the decompression with some heating during the post-peak stage, mostly representing the conditions of about 1.4-1.6 GPa and 580~C-640~C, and their growth is favored by the dehydration of lawsonite into zoisite or epidote, but most of the garnet, omphacite or phengite in the HP eclogite still preserve their compositions at peak condition, and they are not obviously equilibrious with the hornblendes.
基金the National Natural Science Foundation of China(49732070 ,49902018)the National Key Project for Basic Research on the Tibetan Plateau(G1998040805)the Key Project of the Ministry of Land and Resources of China(20010201).
文摘Eclogites have been recently discovered in the Xitieshan area in the middlesegment of the northern margin of the Qaidam basin. These eclogites, together with those recognizedearlier in the Yuka area of the western segment of the northern margin of the Qaidam basin and inthe Dulan area of the eastern segment of the northern margin of the Qaidam basin, form an eclogitebelt with a length of 350 km. A comparison of the eclogites from the Yuka and Xitieshan areassuggests that they show different country rocks, microtextures, mineral assemblages, and especially,different peak temperatures, PT paths during decompression and isotopic features. Eclogites fromthe Yuka area bear evidence of prograde metamorphism, such as prograde mineral relics in garnet andgrowth zoning of garnet, and hairpin-shaped PT paths with coincidence of the baric and thermal peaksof metamorphism, which reflect rapid burial and uplift. Sm-Nd isotopic determination shows obviousSm-Nd disequilibrium, and no isochron ages of Early Paleozoic metamorphism was obtained. On thecontrary, the Xitieshan eclogite was subjected to metamorphism of higher eclogite-facies andpost-eclogite-facies temperatures, showing an obvious granulite-facies overprint. A tentative PTpath for the Xitieshan area suggests that the baric peak preceded the thermal culmination. Wholerock-garnet-omphacite Sm-Nd isotopic data give an isochron age in the Early Paleozoic. Thedifferences between the two eclogites imply their different tectonic-thermal history during theirburial and uplift.
文摘The Dabie orogen, Eastern Qinling orogen and Eastern Kunlun orogen are the major components of the Central Mountain Ranges of China and each has distinctively metamorphic processes in their oldest rock units. The Dabie orogen oldest rock units had experienced an intermediate-higher pressure, upper amphibolite to lower granulite facies metamorphism in the Indosinian intracontinental subduction collision event. The clockwise pt path, synchronous attainment of t max and p max and a segment of high slope retrograde path suggest a tectono driven rapid exhumation of the oldest rock units to upper middle crustal level following the end of the subduction collision process. The oldest rock units, also called Qinling Group, of Eastern Qinling Mountains suffered intensively collisional metamorphism at an immature plate tectonic framework during Jinningian movement about 1 000 Ma ago. The clockwise pt path with reach of t max following several hundreds of MPa decreasing from p max suggests that the denudation of the deeply burial rock units was due essentially to isostatic relaxation. During the Caledonian stage, the highly metamorphosed oldest rock units suffered from a high t thermal event in arc environment and superimposed by contact metamorphism. After thermal peaks, the rock units were exhumed in a short distance and cooled down isobarically. No regional metamorphism higher than upper greenschist facies condition since 300 Ma has been traced within exposed rocks in the eastern portion of Northern Qinling orogen. The oldest rock units in the Eastern Kunlun orogen were metamorphosed to upper amphibolite facies to lower granulite facies rocks early or during the Luliang movement (some 1 800 Ma ago). The high grade metamorphic rock units had a long resident time at the deep crustal level, and were exhumed to middle upper crustal level during the Caledonian to Hercynian tectonometamorphic events. Shallow erosion of the orogenic belt led to good preservation of the low pressure metamorphic belt.
基金the National Natural Science Foundation of China (Grant Nos. 49972028, 49632204 and 49772103) and the major state basic research development program (G1999075508).
文摘According to the field occurrences and petrological study, the low temperature eclogite facies metamorphic rocks in Western Tianshan of Xinjiang can be divided into five types: (i) massive glaucophane-epidote eclogites and glaucophane-paragonite eclogites; (ii) schistose or gneissic mica eclogites; (iii) banded calcite eclogites; (iv) pillow glaucophane eclogites; (v) garnet-omphacite quartzites. Their eclogite facies metamorphism has undergone four stages of evolution: (i) pre-peak lawsonite-blueschist facies stage,T = 350–4000°C,P = 0.7–0.9 GPa; (ii) peak eclogite facies stage,T = 530 ± 20°C,P = 1.6–1.9 GPa; (iii) retrograde epidote-blueschist facies stage, T=500–530°C,P = 0.9–1.2 GPa and (iv) retrograde blueschist-greenschist facies stage,T= 450–550°C,P= 0.7–0.8 GPa. The metamorphic PT path of Western Tianshan eclogites is characterized by clockwise ITD resulting from the subduction of Tarim plate northward to Yili-Central Tianshan plate followed by fast uplift to the surface. But there were at least two stages of blueschist facies retrograde metamorphism overprinted during their uplift.
