检索结果-南通市图书馆

Zircon Record of Ocean-Continent Subduction Transition Process of Dulan UHPM Belt, North Qaidam

在线全文

学校读者我要写书评

暂无评论

Journal of Earth Science 2015年第5期26卷 617-625页

作者： Jianzhou Yang Xiaochi Liu yuanbao wu Yanling Sun Department of Earth Sciences China University of GeosciencesWuhan State Key Laboratory of Lithospheric Evolution Institute of Geology and Geophysics Chinese Academy of Sciences

The North Qaidam UHPM（ultra-high pressure metamorphism） belt is a typical continental subduction-collision belt containing continental crust deep subduction metamorphic products and oceanic crust relics, And it is an ideal region to study the ocean-continent transition and exhumation mechanism of oceanic UHP rocks during continental deep subduction process. In this paper, we report integrated in situ U-Pb, Lu-Hf and O isotope analyses of zircons from a serpentinized harzburgite as well as U-Pb dating for zircons from a kyanite eclogite from the North Qaidam Dulan UHPM terrane, and use these data to discuss the ocean-continent transition and exhumation mechanisms of oceanic UHP rocks during continental deep subduction. The serpentinized harzburgite was dated at 448±9 Ma, consistent with 455±5 Ma age for the kyanite eclogite within analytical errors. Zircons from the serpentinized harzburgite have uniform 176Hf/177 Hf values ranging from 0.282 842 to 0.282 883 and εHf（t） values from 11.6 to 13.3. Zircon δ^18O values of the serpentinized harzburgite vary from 4.47‰ to 5.29‰, slightly lower than the value of 5.3‰±0.6‰ for the normal mantle zircon. These Hf-O isotopic features indicate that the protolith of the serpentinized harzburgite was derived from depleted-mantle source, and might have experienced high-temperature rock-water interaction. Therefore, the serpentinized harzburgite was possibly located in the lower part of an oceanic section. The serpentinized harzburgite and kyanite eclogite were both formed due to the subduction of oceanic crust. The UHP metamorphism occurred successively from the oceanic crust to continental crust rocks of the North Qaidam UHP terrane. Low-density serpentinized peridotite and continental rocks possibly have negative buoyancy and play a key effect on preservation and exhumation of high-density oceanic eclogite.

关键词： continental deep subduction ocean-continent transformation North Qaidam harzburgite eclogite

SHRIMP zircon U-Pb dating for two episodes of migmatization in the Dabie orogen

在线全文

学校读者我要写书评

暂无评论

Chinese Science Bulletin 2007年第13期52卷 1836-1842页

作者： wu yuanbao TANG Jun ZHANG ShaoBing ZHAO ZiFu State Key Laboratory of Geological Processes and Mineral Resources Faculty of Earth Sciences China University of Geosciences Wuhan 430074 China CAS Key Laboratory of Crust-Mantle Materials and Environments School of Earth and Space Sciences University of Science and Technology of China Hefei 230026 China Beijing SHRIMP Center Chinese Academy of Geological Sciences Beijing 100037 China

Zircon CL imaging and SHRIMP U-Pb dating were carried out for migmatite in the Dabie orogen. Zircons from the Manshuihe migmatite show clear core-rim structures. The cores display sector or weak zoning and low Th/U ratios of 0.01 to 0.17, indicating their precipitation from metamorphic fluid. They yield a weighted mean age of 137±5 Ma. By contrast, the rims exhibit planar or nebulous zoning with relatively high Th/U ratios of 0.35 to 0.69, suggesting their growth from metamorphic melt. They give a weighted mean age of 124±2 Ma. Zircons from the Fenghuangguan migmatite also display core-rim structures. The cores are weakly oscillatory zoned or unzoned with high Th/U ratios of 0.21 to 3.03, representing inherited zircons of magmatic origin that experienced different degrees of solid-state recrystallization. SHRIMP U-Pb analyses obtain that its protolith was emplaced at 768±12 Ma, consistent with middle Neoproterozoic ages for protoliths of most UHP metaigneous rocks in the Dabie-Sulu orogenic belt. By contrast, the rims do not show significant zoning and have very low Th/U ratios of 0.01 to 0.09, typical of zircon crystallized from metamorphic fluid. They yield a weighted 206Pb/238U age of 137±4 Ma. Taking the two case dates together, it appears that there are two episodes of zircon growth and thus migmati-tization at 137±2 Ma and 124±2 Ma, respectively, due to metamorphic dehydration and partial melting. The appearance of metamorphic dehydration corresponds to the beginning of tectonic extension thus to the tectonic switch from crustal compression to extension in the Dabie orogen. On the other hand, the partial melting is responsible for the extensional climax, resulting in formation of coeval migmatite, granitoid and granulite. They share the common protolith, the collision-thickened continental crust of mid-Neoproterozoic ages.

关键词：混合岩锆石脱水处理溶解作用

Paleoproterozoic mafic dyke from Kongling terrain in the Yangtze Craton and its implication

在线全文

学校读者我要写书评

暂无评论

Chinese Science Bulletin 2009年第5期54卷 1098-1104页

作者： PENG Min wu yuanbao WANG Jing JIAO WenFang LIU XiaoChi YANG SaiHong State Key Laboratory of Geological Processes and Mineral Resources Faculty of Earth Sciences China University of Geosciences Wuhan 430074 China State Key Laboratory of Continental Dynamics Department of Geology Northwest University Xi'an 710069 China

Mafic dyke is a sign of regional extension, and thus has important tectonic significance. A great amount of mafic dykes occur in the Kongling terrain of the Yangtze Craton, which have great bearing on the early evolution of the Yangtze Craton. Their ages, however, have not been well constrained. In this paper we report an integrated study of zircon U-Pb age and Hf isotope compositions for a mafic dyke in the Kongling terrain. The zircons yielded a weighted mean 207Pb/206Pb age of 1852±11Ma, which represents its intrusion age. They have εHf(t) values of -6.3 to 0.5, with a weighted mean of -3.06±0.88, suggesting that the mafic dyke came from metasomatic mantle. The results indicate that the Yangtze Block had transformed into post-collisional extensional regime at ca. 1850 Ma. In the same period, the Yangtze Craton shows enough rigidity to produce brittle rupture, and thus has the characteristics of a craton.

关键词：扬子克拉通镁铁质古地形岩墙加权平均同位素组成构造意义早期演化

Neoarchean granitic rocks from the Jiamiao area of the Dabie orogen:Implications on the formation and early evolution of the Yangtze Craton

在线全文

学校读者我要写书评

暂无评论

Science China Earth Sciences 2022年第8期65卷 1568-1585页

作者： Yang TIAN Wei WANG Wei JIN yuanbao wu Jing WANG Xin DENG Sifang HUANG wuhan Center of Geological Survey China Geological SurveyWuhan430205China State Key Laboratory of Geological Processes and Mineral Resources School of Earth SciencesChina University of GeosciencesWuhan430074China Research Center for Petrogenesis and Mineralization of Granitoid Rocks China Geological SurveyWuhan430205China Institute of Geology Chinese Academy of Geological SciencesBeijing100037China Department of Surveying and Planning Shangqiu Normal UniversityShangqiu476000China

Archean rock exposures in the Yangtze Craton of South China are scarce and have been only studied in small-scale outcrops for understanding its early crustal *** investigations have been carried out for three Neoarchean gneissic granitic plutons from the Dabie orogen in the northeastern margin of the Yangtze *** U-Pb geochronology constrains the emplacement of high-K monzogranite at 2645±30 Ma,high-K syenogranite at 2630±37 Ma and Na-rich granodiorite at 2497±29 *** findings provide direct evidence for the existence of∼2.7-2.5 Ga rocks in the Dabie orogen,which significantly contribute to the distribution and evolution of Neoarchean basement rocks in the Yangtze *** crystals from the three granite samples giveεHf(t)values of−0.9 to 3.7,−4.2 to−0.4 and−4.7 to 0.1,respectively,corresponding to T_(DM2) ages of 3186-2909,3372-3141 and 3297-3005 *** magmatic zircons have δ^(18)O values of 5.06±0.27‰to 5.79±0.30‰(average 5.59‰),6.14±0.24 to 7.35±0.26‰(average 6.87‰)and 5.95±0.17‰to 7.09±0.17‰(average 6.55‰),*** the possible decrease of δ^(18)O value due to the lead loss during post-crystallization alteration,the primary δ^(18)O values might be substantially higher than those of the normal mantle zircon value(δ^(18)O=5.3±0.6‰).These isotopic data indicate that the Jiamiao Neoarchean granites were largely generated through reworking of Paleo-Mesoarchean basement rocks with a minor contribution of supracrustal *** our findings with previous results,we infer that the Archean-Paleoproterozoic complexes/terranes of the Yangtze Craton have distinct petrogenesis and the timings of the transition from Na-rich to high-K granites,crustal growth,and tectonothermal evolution before∼2.0 ***,all of them underwent metamorphism at about 2.0 *** observations also reveal that the Yangtze Craton might comprise several microcontinents that evolved individually and collided to form a unified craton a

关键词： Zircon U-Pb age Hf-O isotopes Neoarchean Dabie orogen Yangtze Craton

In-situ trace element analyses of zircons from Dabieshan Huangzhen eclogite:Trace element characteristics of eclogite-facies metamorphic zircon

在线全文

学校读者我要写书评

暂无评论

Chinese Science Bulletin 2002年第16期47卷 1398-1401页

作者： wu yuanbao CHEN Daogong XIA Qunke TU Xianglin CHENG Hao Department of Earth and Space Science University of Science and Technology of ChinaHefei 230026China Guangzhou Institute of Geochemistry Chinese Academy of SciencesGuangzhou 510640China

The internal structures of zircons in eclogite from Huangzhen have been studied by cathodoluminescence (CL) microscopy. Two growth stages were distinguished: protolith magmatic cores and metamorphic overgrowth rims. These different domains were analyzed for trace elements using LAM-ICP-MS. The protolith and the overgrowth zircons have different trace elements characteristics. The trace element contents of protolith zircons are high and very variable. The overgrowth zircons show a typical trace element feature of equilibrium with garnet, e.g. low contents of HREE (132.2-197.6μg/g) and small differential degree of HREE ((Yb/Gd)cN=8.6-11.9). The contents of Nb, Ta and the ratio of Nb/Ta are lower in the metamorphic domains (0.5-1.4μg/g, 0.7-1.5μg/g, 0.3-1.3, respectively) than in the protolith domains (3.8-19.7μg/g, 2.7-12.1μg/g, 1.0-4.6, respectively). This is the first time to give the evidence that the metamorphic zircon equilibrates with the rutile, which formed during the peak metamorphic stage.

关键词： eclogite zircon trace elements rutile.

Oxygen isotopic compositions of zircons from pyroxenite of Daoshichong, Dabieshan: Implications for crust-mantle interaction

在线全文

学校读者我要写书评

暂无评论

Chinese Science Bulletin 2002年第17期47卷 1466-1469页

作者： XIA Qunke E.Deloule wu yuanbao CHEN Daogong CHENG Hao Department of Earth and Space Sciences University of Science and Technology of ChinaHefei 230026China CRPG-CNRS BP2054501 Vandoeuvre CedexFrance

Oxygen isotopic compositions of zircons from pyroxenite (-145 Ma) of Daoshichong, Dabieshan have been measured by an ion microprobe. Both within the single grain and among different grains, oxygen isotopic ratios are homogeneous, σ18O = (7.66‰±0.46)‰(1 SD, 1σ=0.10, n = 22). High σ18O values indicate that the mantle-derived parent magma of Daoshichong pyroxenite have undergone interaction with crustal materials. Combing with other geo-chemical constraints, the way of crust-mantle interaction is suggested to be source mixing other than crustal contamination. The time interval between crust-mantle interaction and formation of the parent magma of Daoshichong pyroxenite is less than several million years. The crustal component involving in crust-mantle interaction is mafic lower crust, and the parent magma of pyroxenite possibly contain large proportion (>37%) of such lower crust.

关键词： zircon oxygen isotope ion microprobe Daoshichong Dabieshan.

Oxygen isotopic heterogeneity in the mantle: Evidence from clinopyroxene megacrysts of Nüshan, eastern China

在线全文

学校读者我要写书评

暂无评论

Chinese Science Bulletin 2002年第3期47卷 181-186页

作者： XIA Qunke Dallai Luigi CAO Hong CHEN Daogong wu yuanbao CHENG Hao Department of Earth and Space Sciences University of Science and Technology of ChinaHefei 230026China Stable isotope lab of Centre di Studio per il Quaternario el'EvoluzioneAmbientale-CNR University of Rome“La Sapienza"Italy Anbui Institute of Geological Experiments Hefei 230001China

Major element, REE and oxygen isotopic com-positions of fourteen clinopyroxene megacrysts from Nushan, eastern China have been obtained. They are believed to rep-resent crystallization products of one mantle-derived alkali basaltic magma. Oxygen isotopic ratios are homogeneous within the same sample, but heterogeneous among different samples, δ18O values of these megacrysts are from 4.86‰ to 6.48‰. We suggest that the oxygen isotopic variation of cli-nopyroxene megacrysts should be inherited from their source magma, and the heterogeneity of source magma re-sults from contamination of subducted oceanic materials.

关键词： oxygen isotope heterogeneity laser fluorination clino-pyroxene nushan.

Zircon SIMS ages and chemical compositions from Northern Dabie Terrain:Its implication for pyroxenite genesis

在线全文

学校读者我要写书评

暂无评论

Chinese Science Bulletin 2001年第12期46卷 1047-1050页

作者： CHEN Daogong WANG Xiang E.Deloule LI Binxian XIA Qunke CHENG Hao wu yuanbao Department of Earth and Space Sciences University of Science and Technology of ChinaHetei 230026China Department of Earth Sciences Nanjing UniversityNanjing 210008China CRPG-CNRS Nancy 54501France

We present the results of a detailed micro-scale investigation of zircons from pyroxenites, Daoshicong Northern Dabie using a combination of SIMS and ICPMS. The SIMS measurements gave ages of 134-159 Ma. Its average of (144.516.2) Ma is interpreted as the best estimate of the pyroxenite intrusion. The crystallization of zircons continued for quite a long time and underwent slow cooling. The pyroxenites are products of post-collision magmatism. The REE pattern is HREE-enriched, and its HREE concentrations fall between the magmatic and metamorphic range of gneissic zircons from the Dabie area, which indicate the involvement of crust material in its mantle source.

关键词： zircon SIMS age zircon trace element crust-mantle interaction Northern Dabie pyroxenite.

在线全文

学校读者我要写书评

暂无评论

秦岭造山带古生代岩浆作用及地球动力学意义

地球科学 2019年第12期44卷 4173-4177页

作者：吴元保中国地质大学地球科学学院

秦岭造山带记录了华南华北板块聚合的完整过程.古生代岩浆岩记录了造山过程中的壳幔相互作用和造山带演化的动力学过程.古生代的中基性岩浆岩揭示了俯冲隧道内变质脱水交代岩石圈地幔过程,其中富水基性杂岩为富钾基性岩,地球化学特征显... 详细信息

秦岭造山带记录了华南华北板块聚合的完整过程.古生代岩浆岩记录了造山过程中的壳幔相互作用和造山带演化的动力学过程.古生代的中基性岩浆岩揭示了俯冲隧道内变质脱水交代岩石圈地幔过程,其中富水基性杂岩为富钾基性岩,地球化学特征显示其地幔源区经历了洋壳沉积物的交代;看丰沟岩体为高镁闪长岩,地球化学特征显示其来自经历俯冲流体交代的地幔源区.通过对古生代岩浆岩的研究发现,其具有明显的时空分布规律,它们对应于原特提斯洋俯冲、后撤、前进和回转等过程.所以壳幔相互作用发生在原特提斯洋俯冲过程中.

关键词：秦岭造山带古生代岩浆作用地球动力学.