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Lithospheric seismic fabrics of Sulu ultrahigh-pressure metamorphic belt

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Science China Earth Sciences 2005年第5期48卷 585-600页

作者： YANG Wencai 1 , YANG Wuyang 1 , JIN Zhenmin 2 & CHENG Zhenyan 1 1. Institute of Geology, Chinese Academy of Geological Sciences, Beijing 100037, China 2. China University of Geosciences, Wuhan 430074, China 1. Chinese Academy of Geological Sciences Institute of Geology 100037 Beijing China 2. China University of Geosciences 430074 Wuhan China

Calibration of seismic reflectors appearing in the crust of the Chinese continent sci- entific drilling site can be completed through the correlation studies between direct evidences, such as the drill cores, and geophysical signatures; therefore the interpretation of geophysical data could produce reliable results of crustal structure and composition. On the other hand, there are two Cenozoic volcanoes close to the scientific drilling site; analyzing composition of xenoliths existent in the volcanoes and evaluating their seismic velocities can also offer information about the mantle and lower crust. After the calibration via cores and well-logging data, the seismic re- flectors appearing in the UHP belt can be caused by lithological changes within the UHP rock slice, ductile shearing rock-suites, and later fracture zones. Among these sources, ductile shearing resulted in displacement and detachment of original rock-sheets, producing some rock-interbeds of several hundred meters thick that are named the ductile shearing rock-suites. A suite consists of mylonized gneiss and eclogite slices that underwent shearing, becoming the major mechanism responsible to generate regional strong reflections. The UHP rock-slice is characterized by complicated structures and high density, high seismic velocity and high electri- cal resistivity, its thickness is usually less than 11 km. Velocity and density of the gneiss-layer beneath gradually tend to normal with increasing depth. Based on the xenoliths we can infer that the middle crust contains a lot of gneisses, and the lower crust consists of different granulites. The lithospheric mantle has multi-layer structures and consists mainly of spinal lherzolite and harzburgite, implying late Mesozoic lithospheric thinning. The seismic fabrics with different ori- gins were possible products of different geodynamic processes. For instance, the UHP rock-slice was produced by the UHP metamorphic process and the exhumation of subducted supe

关键词： deep seismic reflection, ultrahigh-pressure belt, Sulu China, calibration of reflectors, lithospheric fabrics.

Extensional deformation of post ultrahigh-pressure metamorphism and exhumation process of ultrahigh-pressure metamorphic rocks in the Dabie massif,China

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Science China Earth Sciences 2000年第3期43卷 225-236页

作者：索书田钟增球游振东 Faculty of Earth Sciences China University of Geosciences Wuhan 430074 China

A detailed tectonic analysis demonstrates that the present observed regional tectonic configuration of the ultrahigh-pressure metamorphic terrane in the Dabie massif was mainly formed by the extension processes of the post-Indosinian continent-continent oblique collision between the Sino-Korean and Yangtze cratons and ultrahigh-pressure metamorphism (UHPM). The configuration is characterized by a regional tectonic pattern similar to metamorphic core complexes and by the development of multi-layered detachment zones. On the basis of the identification of compressional and extensional fabrics, it is indicated that the exhumation and uplift of ultrahigh-pressure (UHP) metamorphic rocks from the mantle depth to the surface can be divided into at least three different decompression retrogressive metamorphism and tectonic deformation stages, in which the subhorizontal crustal-scale extensional flow in the middle-lower crust under amphibolite facies conditions is an important geodynamic process in the exhumation of UHP metamorphic rocks. Moreover, the extensional flow is probably driven by delamination and magmatic underplating of thickened lithospheric mantle following the continental oblique collision.

关键词： ultrahigh-pressure metamorphic rock extensional deformation detachment zon e exhumation Dabie massif.

Fluid inclusions in whiteschist in the ultrahigh-pressure metamorphic belt of Dabie Shan,China

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Chinese Science Bulletin 2002年第12期47卷 1028-1032页

作者： Hongrui Fan Jingbo Liu Jinghui Guo Kai Ye Bolin Cong Chinese Acad Sci Inst Geol & Geophys Beijing 100029 Peoples R China

Hualiangting whiteschist in the Dabie Shan ultrahigh-pressure eclogite complex is a specific Mg-Al-rich metamorphic rock. Its protolith was a felsic dyke, which suffered replacement by high-pressure fluids during ec-logite-facies metamorphism. Based on fluid inclusion results in whiteschist, primary high-pressure fluids are CO2-bearing aqueous solutions. Those prove that there exists CO2-H2O fluid during the ultrahigh-pressure metamorphism. Pseu-dosecondary H2O inclusions were trapped during ultra-high-pressure exhumation, whereas secondary H2O inclusions were related to the latest evolutionary stage of the ultrahigh-pressure exhumation.

关键词： fluid inclusion whiteschist ultrahigh-pressure Dabie Shan.

Could tectonic overpressure cause ultrahigh-pressure metamorphism?

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Chinese Science Bulletin 1999年第24期44卷 2295-2298页

作者： Qingchen Wang Jingbo Liu Bolin Cong Chinese Acad Sci Inst Geol Beijing 100029 Peoples R China

Could ultrahigh-pressure metamorphic rocks be caused, at depth of 32 km, by tectonic overpressure resulting from differential stress? The differential stress is limited by rock strength, which depends on strain rate and temperature. Therefore, tectonic overpressure could not go beyond 1 GPa, and could not cause the uitrahigh-pressure metamorphism.

关键词： ultrahigh-pressure tectonic overpressure plastic deformation.

Anti-blocking performance of ultrahigh-pressure waterjet assisted furrow opener for no-till seeder

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International Journal of Agricultural and Biological Engineering 2020年第2期13卷 64-70,F0002页

作者： Hongnan Hu Hongwen Li Qingjie Wang Jin He Caiyun Lu Yingbo Wang Peng Liu College of Engineering China Agricultural UniversityBeijing 100083China China Agricultural University National Institute for Conservation Tillage Beijing 100083China Scientific Observing and Experimental Station of Arable Land Conservation(North Hebei) Ministry of Agriculture and Rural AffairsBeijing 100083China

No-till planting method is widely used for maize-wheat two-crops-a-year area in the North China ***,cruel soil conditions,especially the large number of maize stalks which are hard to cutoff covering,often cause an unsatisfying planting *** on the authors’previous investigation,ultrahigh-pressure(UHP)waterjet is capable to solve this problem and obtain qualified ***,a UHP waterjet assisted furrow opener for no-till seeder was *** tests showed that double-disc furrow openers worked well with UHP waterjet,since the sharpened disc blades could help to cut soil and residue,meanwhile,minimize soil *** surface method(RSM)was used to investigate the relationship among forward speed,waterjet pressure,jet impingement angle and anti-blocking performance(stalks cutoff ratio and depth of soil cutting),and a Box-Behnken three-factor design was used to identify the optional operation parameters.A total of 17 combinations were conducted,and the results showed all three operation parameters significantly affected anti-blocking *** cutoff ratio and depth of soil cutting increased with the increase of waterjet pressure,jet impingement angle,and decreased with the increase of forward *** optimization analysis indicated that when waterjet pressure was 267-280 MPa,jet impingement angle was 80.2°to 90.0°and forward speed was 4.00-4.42 km/h,the overall performance of UHP waterjet assisted double-disc furrow opener for no-till seeder was *** cutoff ratio could be above 95%and no blockage *** study may provide a new approach and reference for the anti-blocking technology of no-tillage seeding.

关键词： waterjet ultrahigh-pressure conservation tillage maize stalks cutting no-till anti-blocking

ultrahigh-pressure P-BEARING TITANITE IN E-CLOGITE AT HOUSHUICHEGOU,SHANDONG PROVINCE,EASTERN CHINA

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Scientia Geologica Sinica 1997年第1期 8-14+16-19页

作者： Ye Kai, Cong Bolin and Ye Danian (Institute of Geology, Chinese Academy of Sciences, Beijing 100029))

ＵＬＴＲＡＨＩＧＨ－ＰＲＥＳＳＵＲＥＰ－ＢＥＡＲＩＮＧＴＩＴＡＮＩＴＥＩＮ牛茫蹋希牵桑裕牛粒裕龋希眨樱龋眨桑茫龋牛牵希眨樱龋粒危模希危牵校遥希郑桑危茫牛牛粒樱裕牛遥危茫龋桑危罷XＵＬＴＲＡＨＩＧＨ┐ＰＲＥＳＳＵ... 详细信息

ＵＬＴＲＡＨＩＧＨ－ＰＲＥＳＳＵＲＥＰ－ＢＥＡＲＩＮＧＴＩＴＡＮＩＴＥＩＮ牛茫蹋希牵桑裕牛粒裕龋希眨樱龋眨桑茫龋牛牵希眨樱龋粒危模希危牵校遥希郑桑危茫牛牛粒樱裕牛遥危茫龋桑危罷XＵＬＴＲＡＨＩＧＨ┐ＰＲＥＳＳＵＲＥＰ┐ＢＥＡＲＩＮＧＴＩＴＡＮＩ?..

关键词： AT HOUSHUICHEGOU,SHANDONG TITANITE P-BEARING ultrahigh-pressure CHINA E-CLOGITE

ultrahigh-pressure(UHP) Low-Al Titanites from carbonate-bearing rocks in Dabieshan-Sulu UHP terrane,Eastern China

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Ultrahigh-Pressure(UHP) Low-Al Titanites from carbonate-bear...

Chronology of ultrahigh-pressure metamorphism in the Dabie Mountains and Su-Lu terrane: I. Sm-Nd isotope system

中国科学院地质与地球物理研究所2002学术年会

作者： JING-BO LIOU SOICHI OMORI SHIGENORI MARUYAMA Laboratory of Lithosphere Tectonic Evolution Institute of Geology and GeophysicsChinese Academy of Sciences Department of Earth and Planetary Sciences Tokyo Institute of Technology2-12-1 OokayamaMeguroTokyo 152Japan

Titanites previously reported from high-pressure rocks commonly contain high Al and F *** has led previous workers to conclude that high Al and F in titanite can promote its stability field to high-pressure and UHP *** this study,a coesite inclusion was identified in titanite of aragonite- and jadeite-bearing gneiss from the Dabieshan UHP metamorphic terrane of eastern *** also found UHP titanite in carbonate-bearing garnet-clinopyroxenite from the Sulu UHP ***,both types of the UHP titanite mentioned above contain low Al and F ***,our data indicate that the high-Al and F contents are not necessary criteria for stabilizing titanite to UHP *** is inferred that the UHP titanite is formed via the reaction TiO+CaCO+SiO=CaTiSiO+CO,and that the presence of UHP assemblage of aragonite+ rutile+coesite in the host rock and very low X value in the coexisting fluid are crucial conditions for the formation of these UHP titanite.

关键词： ultrahigh-pressure titanite low-Al cabonate Dabie-Sulu

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Science China Earth Sciences 1996年第6期39卷 597-609页

作者：李曙光肖益林葛宁洁陈移之 Emil Jagoutz Department of Earth and Space Sciences University of Selena of Technology of China Hefei 230026 C'hina Department of Earth and Space Sciences University of Science and Technology of China Hefei 230026 China) Department for Cosmochermistry Max-Planck-Institut fur Chemie D-55020 Mainz. Germany

If the protolith of coesite-bearing eclogite was gabbro, it could undergo ultrahigh-pressure metamorphism under dry condition. In this case, the Hocking temperatures of those minerals could be higher, so that Nd isotope disequilibrium between minerals could be observed. If the protolith of coesite-bearing edogite was metabasalt, amphiboles in the metabasalt were decomposed during ultrahigh-pressure metamorphism and released water. Thus Nd isotope compositions between the minerals were in equilibrium because the blocking temperatures of those minerals could he lower. The secondary alteration and fluid-rock interaction in high-pressure are major problems for Sm-Nd dating of eclogite. The reliable Sm-Nd isotopic ages of coesite-bearing eclogite from the Dabie Mountains and Su-Lu terrane range from 221 to 232 Ma. They are slightly lower, but very close to the peak metamorphic ages of the eclogites. The cold eclogite from the Sujiahe complex could be oceanic subduction origin in the Paleozoic.

关键词： Dabie Mountains Su-Lu terrane ultrahigh-pressure metamorphie rocks Sm-Nd isotopic dating.

Deep structures of the east Dabie ultrahigh-pressure metamorphic belt, East China

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Science China Earth Sciences 2003年第6期46卷 612-624页

作者：杨文采 InstituteofGeology ChineseAcademyofGeologicalSciences

The geophysical investigations with seismic and MT methods were carried out in the east Dabie Mountain area in 1997, producing detailed results about crustal structures with good compatibility between different geophysical methods. After integrated interpretation of both avail-able geophysical and geological data, the author compiles a crustal tectonic section across the east Dabie Mountain (Plate II), which provides much more structural details with improved reliabil-ity due to geophysical constraints applied to the deep structures. The east Dabie orogenic belt can be divided into 4 geologic units from north to south: the north Huaiyang, the north Dabie, the south Dabie and the Susong. The Mesozoic northward subduction of the Yangtze craton caused the Yangtze crust to insert into the middle and lower crust of the Susong high-pressure metamorphic zone, while the middle and lower crust below the north Huaiyang and the Hefei basin contains the basement of the Sino-Korean craton. The middle and lower crust of the south Dabie is rather dif-ferent from that of the north Dabie, showing that the north and the south Dabie had different evolu-tional trajectories and should not belong to a single tectonic unit. The current crustal pattern has resulted mainly from deformation caused by the post-collisional intracontinental subduction of both the Yangtze and Sino-Korean cratons before the late Jurassic, and deformation caused by later crustal extension including doming and unroofing around the north Dabie. It can be inferred that the suture zone of the Triassic collision between the Sino-Korea and the Yangtze was located along the Xiaotian-Mozitan fault zone, which contains a group of normal faults dipping north in the upper crust, but becomes steep thrusts of dipping south in the middle crust, accompanied by ex-tensive deformation between this fault zone and the Hefei basin. The middle crust below the north Huaiyang unit is connected to the basement of the Sino-Korean craton,

关键词： geophysical investigations, crustal tectonic sections, collisional belt, ultrahigh-pressure zone, east Dabie Mountain.