6 results on '"Wang, Jianqi"'
Search Results
2. U-Pb Zircon Geochronology and Geochemistry of Granitoids in the Douling Group in the Eastern Qinling
- Author
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Zhang Chengli, Li Miao, Liu Xiaoming, Liu Ye, Yuan Honglin, Wang JianQi, Wang Tao, and Yan Yunxiang
- Subjects
Dike ,geography ,geography.geographical_feature_category ,biology ,Subduction ,Partial melting ,Geochemistry ,Geology ,Crust ,biology.organism_classification ,Continental margin ,Geochronology ,Petrology ,Lile ,Zircon - Abstract
LA-ICPMS U-Pb zircon dating of the Sanpinggou, Gangou and Fengzishan granitoids in the Douling Group of the Eastern Qinling yields ages of 760-685 Ma, which represents a strong tectono-magmatic event in the southern Qinling during the late Neoproterozoic. Geochemical data show that these intrusions have wide compositions ranging from minor gabbros through diorites to granodiorites. They are relatively enriched in LILE, poor in HFSE and strongly depleted in Nb and Ta, displaying affinities of Ⅰ-type granites formed in an active continental margin with oceanic subduction. In contrast to granitoids, gabbros and enclaves in the granitoids have higher REE abundances, relatively flat REE patterns, lower LILE, slightly higher HFSE and more depletion in Nb and Ta. All these suggest that the gabbros were formed by partial melting of the upper mantle above the subduction zone and the granitoids by the partial melting of the lower crust. Combined with regional geological data, the subduction-related granitoids in the Douling Group, together with the Tuwushan A-type granite with an age of 725 Ma and contemporaneous basic dikes in the Wudang Block, provide evidence for local subduction of oceanic basins between different blocks during the rifting in the Southern Qinling in the Neoproterozoic. Thus, the coexistences of various magmatic rocks formed in different tectonic environments indicate a complicated tectonic evolution and variety of tectonic frameworks in the Qinling area in the Neoproterozoic.
- Published
- 2010
3. Geochemistry and spatial distribution of OIB and MORB in A’nyemaqen ophiolite zone: Evidence of Majixueshan ancient ridge-centered hotspot
- Author
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Guo Anlin, Liu Ye, Zhang Guowei, Wang JianQi, Zheng Jiankang, and Sun Yangui
- Subjects
Incompatible element ,geography ,geography.geographical_feature_category ,Volcano ,Hotspot (geology) ,Geochemistry ,General Earth and Planetary Sciences ,Mid-ocean ridge ,Metasomatism ,Mafic ,Ophiolite ,Mantle plume ,Geology - Abstract
The mafic volcanic association is made up of OIB, E-MORB and N-MORB in the A’nyemaqen Paleozoic ophiolites. Compared with the same type rocks in the world, the mafic rocks generally display lower Nb/U and Ce/Pb ratios and some have Nb depletion and Pb enrichment. The OIB are LREE-enriched with (La/Yb) N =5―20, N-MORB are LREE-depleted with (La/Yb) N = 0.41―0.5. The OIB are featured by incompatible element enrichment and the N-MORB are obviously depleted with some metasomatic ef-fect, and E-MORB are geochemically intermediated. These rocks are distributed around the Majixue-shan OIB and gabbros in a thickness greater than a thousand meters and transitionally change along the ophiolite extension in a west-east direction, showing a symmetric distribution pattern as centered by the Majixueshan OIB, that is, from N-MORB, OIB and E-MORB association in the Dur’ngoi area to OIB in the Majixueshan area and then to N-MORB, OIB and E-MORB assemblage again in the Buqing-shan area. By consideration of the rock association, the rock spatial distribution and the thickness of the mafic rocks in the Majixueshan, coupled with the metasomatic relationship between the OIB and MORB sources, it can be argued that the Majixueshan probably corresponds to an ancient hotspot or an ocean island formed by mantle plume on the A’nyemaqeh ocean ridge, that is the ridge-centered hotspot, tectonically similar to the present-day Iceland hotspot.
- Published
- 2007
4. The Discovery of Late Ordovician Granodiorite in the Xiemisitai Area, Xinjiang and its Geological Significance.
- Author
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WANG, Juli, HU, Yang, WANG, Jianqi, and WANG, Min
- Subjects
GRANODIORITE ,PETROLOGY ,OROGENIC belts ,GEOCHEMISTRY ,ZIRCON - Abstract
The article focuses on a study on the formation age and tectonic environment, magma source and petrogenesis of the newly discovered granodiorite mass near Yinisala in the Xiemisitai area in China. The study determined the crystallization age of the Yinisala granodiorite and formation of Yinisala granodiorite in the tectonic setting of continental margin arc.
- Published
- 2017
- Full Text
- View/download PDF
5. Determination of trace and rare-earth elements in Chinese soil and clay reference materials by ICP-MS.
- Author
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Liu, Ye, Diwu, Chunrong, Zhao, Yan, Liu, Xiaoming, Yuan, Honglin, and Wang, Jianqi
- Subjects
RARE earth metals ,CLAY soils ,GEOCHEMISTRY ,FLUORIDES ,SOIL chemistry ,PRECISION (Information retrieval) ,UNCERTAINTY (Information theory) - Abstract
Inductively coupled plasma mass spectrometry (ICP-MS) has become a powerful tool for providing reliable analytical results in many laboratories around the word. In this study, the mixture of HF and HNO acids in high-temperature and high-pressure closed-vessel digestion technique were used to decompose some Chinese reference materials, and thirty seven elements were determined by ICP-MS. Most of the results for Chinese soil reference materials were found to be in reasonable agreement with the reference values, except Cs, Ta, Li, Ge, Zn, Nd, Tb and Ta whose values need to be revised. Their precisions were typically lower than 5% RSD. However, the Precisions of Chinese clay reference materials, especially for GBW03102 and GBW03102a, were significantly different with reference values, probably reflecting the existence of a coarser-grained fraction (>70 μm) in samples, and the formation of fluorides in Al-rich samples during sample decomposition by using the mixture of HF and HNO acids. Moreover, thirty-seven trace elements covering the mass range from Li to U in four Chinese clay reference materials were firstly provided with good precision and accuracy in this study. [ABSTRACT FROM AUTHOR]
- Published
- 2014
- Full Text
- View/download PDF
6. Melting-induced fluid flow during exhumation of gneisses of the Sulu ultrahigh-pressure terrane
- Author
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Zong, Keqing, Liu, Yongsheng, Hu, Zhaochu, Kusky, Timothy, Wang, Dongbin, Gao, Changgui, Gao, Shan, and Wang, Jianqi
- Subjects
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GEOCHEMISTRY , *FUSION (Phase transformation) , *GNEISS , *EXHUMATION , *QUARTZ , *FRACTURE mechanics , *ECLOGITE , *ZIRCON , *METAMORPHISM (Geology) , *GEOLOGICAL formations - Abstract
Abstract: Hydrothermally altered rocks are products of fluid–rock interactions, and typically preserve numerous quartz veins that formed as chemical precipitates from fluids that fill up cracks. Thus, quartz veins are the record of the fluid system that involved fracture flow in the direction of changing temperature or pressure. In order to decipher the fluid activity in the Sulu ultrahigh-pressure (UHP) terrane in eastern China, quartz veins together with an adjacent eclogite lens and the host gneiss were studied. In one location a deformed quartz vein is located at the boundary between the host gneiss and the eclogite lens. The amphibolite-facies overprinting of the eclogite lens decreases from the rim to the core of the lens, with fresh eclogite preserved in the core. The foliated biotite gneiss contains felsic veins and residual phengites. Zircon rims from the gneiss are characterized by melt-related signatures with steep HREE patterns, high Hf contents and negative Eu anomalies, and a pool of weighted average 206Pb/238U analyses reveal an age of 219±3Ma (2σ), which is younger than the UHP metamorphic age (236±2Ma, 2σ) recorded by zircons from the eclogite lens. This suggests that the gneiss in the Sulu UHP terrane could have suffered from partial melting due to phengite dehydration during the “hot” exhumation stage. The formation age of the quartz vein (219±2Ma, 2σ) defined by zircon rims agrees well with the partial melting time (219±3Ma, 2σ) of the host gneiss. The initial 176Hf/177Hf ratios of zircon rims from the quartz vein are obviously lower than zircons from the eclogite lens, but overlap with the coeval zircon domains from the nearby granite dikes produced by partial melting of orthogneiss. These observations suggest that the quartz vein and corresponding fluid flow could be associated with partial melting of the host gneiss. On the other hand, amphibole-bearing and HREE-rich zircon rims from the amphibolite pool an amphibolite-facies metamorphic age of 217±5Ma (2σ), overlap with the formation age of the quartz vein. This implies that retrogression of the eclogite lens could have been caused by melting-induced fluid flow. Based on the above observations, we speculate that partial melting of the gneiss in the continental subduction-related UHP belt could have induced a significant fluid flow during the exhumation stage, and thus contributed significantly to the extensive retrogression of eclogites in the Sulu UHP terrane. [Copyright &y& Elsevier]
- Published
- 2010
- Full Text
- View/download PDF
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