检索结果-南通市图书馆

Characteristics and geological significance of olivine xenocrysts in Cenozoic volcanic rocks from western Qinling

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Progress in Natural Science:Materials International 2006年第12期16卷 1300-1306页

作者： SU Benxun~ 1,2 **, zhang Hongfu~1, XIAO Yan~ 1,2 and ZHAO Xinmiao~ 1,2 (1. State Key Laboratory of Lithospheric Evolution, institute of Geology and Geophysics, chinese academy of sciences, beijing 100029, China 2. Graduate School of chinese academy of sciences, beijing 100039, China) [a]State Key Laboratory of Lithospheric Evolution Institute of Geology and Geophysics Chinese Academy of Sciences Beijing China [b]Graduate School of chinese academy of sciences Beijing China

Cenozoic volcanic rocks from the Haoti, Dangchang County of the western Qinling Mountains, contain a few clearly-zoned olivines. These olivines are relatively big in grain sizes and usually have cracks or broken features. Their cores have similar compositions （Mg#=90.4-91.0） to those for the peridotitic xenoliths entrained in host volcanic rocks and their rims are close to the compositions of olivine phenocrysts （Mg#=85.5-81.9）. The CaO contents in these zoned olivines are lower than 0.1%. These features demonstrate that the clearly-zoned olivines are xenocrysts and disaggregated from mantle peridotites. The zoned texture was the result of the interaction between the olivine and host magma. Available data show that the volcanic rocks would have been derived from the mantle source metasomatized by subducted hydrathermally-altered oceanic crust. The formation of these Cenozoic volcanic rocks was perhaps related to the rapid uplift of the Tibetan Plateau.

关键词： Western Qinling Dangchang Haoti Cenozoic volcanic rocks olivine xenocrysts zoned texture.

Types, Metallogenic Environments and Characteristics of Temporal and Spatial Distribution of Copper deposits in China

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Acta Geologica Sinica(English Edition) 1989年第1期63卷 79-92页

作者： Wang Zhitian and Qin Kezhang beijing institute of Geology for mineral Resources, CNNC, beijing zhang Zhongmin CNNC BEIJING INST GEOL MINERAL RESOURCESBEIJINGPEOPLES R CHINA

Based upon a comprehensive study of 123 copper deposits in China. this paper reaches the following conclusions: 1. The crust in China was solidified pretty late; with the accretion of the plate, the copper mineralization moved towards its margin in space and became successively younger in age. 2. The major copper ore types ever found in the world have mostly been discovered in China, in which the porphyry type seems to be the most important and the massive sulfide type in the transitional bed between marine clastic and carbonate rocks is clearly defined. 3. Carbonate strata are widespread in China and their deposition lasted for a long geological period, so the proportion of copper deposits occurring in them is large as compared with other parts of the world. 4. Seven metallogenic epochs can be recognized, in which the Mesozoic one plays the leading role and the middle(late) Palaeozoic and Cenozoic ones are next in importance. mineralization was comparatively simple in the early geological period. and became diversified later on. In the early epochs copper deposits related to basaltic magmatism and metamorphosed marine sediments predominated, whereas in the later epochs those related to granitic magmatism and continental sedimentation were dominant. 5. There exist in China thirteen metallogenic provinces, of which the Lower Yangtze downwarping belt, Sanjiang fold system, Jiangnan axis and Xikang-Yunnan axis are of greater significance. 6. The crustal mobility in China was rather pronounced, the polycyclic evolution of the crust has resulted in such obvious phenomena as the inheritance of mineralization, the coexistence of various types and the superposition of different genetic types.

关键词： Metallogenic Environments and Characteristics of Temporal and Spatial Distribution of Copper deposits in China Types

Tectonic setting of the Helong Block:Implications for the northern boundary of the eastern North China Craton

在线全文

学校读者我要写书评

暂无评论

Science China Earth sciences 2005年第10期48卷 1599-1612页

作者： zhang Yanbin1, WU Fuyuan1, ZHAI Mingguo1 & LU Xiaoping1,2 1. institute of Geology and Geophysics, chinese academy of sciences, P.O. Box 9825, beijing 100029, China 2. Regional geological and mineral Resources Survey of Jilin Province, Changchun 130062, China institute of Geology and Geophysics chinese academy of sciences beijing China Regional geological and mineral Resources Survey of Jilin Province Changchun China

LA-ICP-MS zircon U-Pb dating indicates that the Bailiping granitic pluton was em-placed during Late Paleozoic to Early Cretaceous (285―116 Ma) by four distinct magmatic epi-sodes, arguing against the previous thought that the Bailiping granites were emplaced during Archean, Proterozoic or Early Paleozoic. It is suggested that the so-called Archean Jincheng-dong granite-greenstone belt, mainly composed of Bailiping granites, should be broken down. Sr-Nd isotopic compositions of the Bailiping granites are similar to those of the Phanerozoic granites in the Xing’an-Mongolian orogenic belt, suggesting that their parental magmas were mainly derived from a juvenile crust with some contamination of ancient crustal materials during magma rising and/or emplacement. Therefore, the basement of the Helong Block is similar to that in the northern Xing’an-Mongolian Orogenic Belt, but different from that of the North China Craton. It is proposed that the Archean Jinchengdong complex in this area is probably an exotic slice from the North China Craton, which indicates that the Fu’erhe-Gudonghe Fault, located in northern part of the Helong area, is not the boundary between the North China Craton and the Xing’an-Mongolian Orogenic Belt. The possible boundary should be located further southward more than 50 km and near the Baitoushan volcano.

关键词： LA-ICPMS ziron U-Pb dating, Bailiping complex, Helong Block, North China Craton, Sr-Nd isotope.

Sequence Stratigraphy and Relative Sea Level Changes in Sinian System of Yichang, Hubei Province

在线全文

学校读者我要写书评

暂无评论

Journal of Earth Science 1996年第1期15卷 29-37页

作者： Wang Ziqiang (Department of Geology and mineral Resources, China University of Geosciences, beijing 100083) Gao Linzhi (institute of Geology, chinese academy of geological sciences, beijing 100037) zhang Linghua Jiang Ganqing zhang Chuanheng Yin Yong (Dep

The study on outcrop sequence stratigraphy of the Sinian section in the Yangtze Gorges an important step in the comprehensive stratigraphy for the Sinian stratotype. In this paper, the base of the Nantuo tillite is selected as the bottom boundary of the Sinian, and the top of the Baimatuo Member of the Dengying Formation is taken as the top boundary. The Sinian lasted from 740 the to 570 Ma. According to the features of sequence boundary facies and the parasequence sets, two supersequences are recognized in the Sinian with six sequences. In this paper, the authors discuss the correlation of those sequences. On the basis of the subsidence rate and the thickness of decompressed deposits, the authors discuss the mechanism of tectonic and sedimentation of the Dengying Formation and the features of high-frequency rhythms as well as the 3rd-order sequences in the Yangtze Gorges.

关键词： Sinian System sequence supersequence stacking parasequence set.

Microfossils from the Wumishan Formation of the Jixian System in the Ming Tombs,beijing,China

在线全文

学校读者我要写书评

暂无评论

Acta Geologica Sinica(English Edition) 1986年第4期 13-22+97-98页

作者： zhang Pengyuan Tianjin institute of Geology and mineral Resources, chinese academy of geological sciences, Tianjin Gu Shuqin Beoing geological Survey, beijing Bureau of Geology and mineral Resources, beijing

Members Ⅰ-Ⅳ of the Wumishan Formation of the Jixian System are exposed respectively in Mt. Cuihua and Mt. Hushan in the Ming Tombs, beijing. Black banded cherts which are extensively developed in this formation contain an abundance ofmicrofossils that are well preserved and variable in form. A study of thin sections shows that the microfossils include 10 genera, 12 species, 3 of. species, 2 indeterminate species and 1 unnamed form, of which 1 genus and 7 species are newly erected. The present assemblage is morphologically comparable to those from the Wumishan Formation in the Western Hills of beijing, Jixian County of Tianjin and Kuancheng of Hebei Province.

关键词： BW Microfossils from the Wumishan Formation of the Jixian System in the Ming Tombs,beijing,China

A challenge to the concept of slip-lines in extrusion tectonics

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Geoscience Frontiers 2011年第1期2卷 23-34页

作者： Yadong Zheng~(a,*),Erchie Wang~b,Jinjiang zhang~a,Tao Wang~c a Key Laboratory of Orogenic Belts and Crustal Evolution,Ministry of Education,School of Earth and Space sciences, Peking University,beijing 100871,China b institute of Geology and Geophysics,chinese academy of sciences,beijing 100029,China c institute of Geology,chinese academy of geological sciences,beijing 100037,China [a] Key Laboratory of Orogenic Belts Crustal Evolution Ministry of Education School of Earth Space sciences Peking University Beijing 100871 China [b] Institute of Geology Geophysics Chinese Academy of Sciences Beijing 100029 China [c] Institute of Geology Chinese Academy of Geological Sciences Beijing 100037 China

Wide-open V-shaped conjugate strike-slip faults in Asia are typically related to extrusion ***,the tectonic model based on the slip-line theory of plasticity has some critical problems associated with *** conjugate sets of slip-lines in plane deformation,according to the theory of plasticity should be normal to each another but,in reality,the angles between the conjugate strike-slip faults,which are regarded as slip-lines in extrusion tectonics in the eastern Mediterranean,Tibet-middle Asia,China and the Indochina Peninsular regions,are always more than 90°(on average～110°) in the direction of contraction. Another problem is that the slip-line theory fails to explain how,in some cases,e.g.,in the Anatolian area in the eastern Mediterranean,the extrusion rate is much higher than the indent *** two major problems are easy to solve in terms of the Maximum-Effective-Moment(MEM) Criterion that predicts that orientations of the shear zones are theoretically at an angle of 54.7°and practically at angles of 55°±10°with theσ- or contractional *** orientations of the strike-slip faults that accommodate extrusion tectonics are,therefore, fundamentally controlled by the MEM *** extrusion is along the MEM-orientations,the extruding rate is normally higher than the indenting rate.

关键词： Extrusion tectonics Slip-line Wide-open V-shaped strike-slip faults MEM-Criterion Strain rate

电弧微铸锻复合增材制造GH4169D高温合金的显微组织与力学性能

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

金属学报 2024年第5期60卷 681-690页

作者：曾立王桂兰张海鸥翟文正张勇张明波华中科技大学材料成形与模具技术国家重点实验室武汉430074 华中科技大学数字制造装备与技术国家重点实验室武汉430074 中国航发北京航空材料研究院北京100095

GH4169D合金作为一种新型的高力学性能和高稳定性的镍基高温合金,在用于制造高性能复杂结构零件方面具有巨大应用价值,但该合金在电弧增材制造中表现出柱状晶粗大、力学性能各向异性等问题。本工作采用电弧微铸锻复合增材制造(hybrid ar... 详细信息

GH4169D合金作为一种新型的高力学性能和高稳定性的镍基高温合金,在用于制造高性能复杂结构零件方面具有巨大应用价值,但该合金在电弧增材制造中表现出柱状晶粗大、力学性能各向异性等问题。本工作采用电弧微铸锻复合增材制造(hybrid arc and micro-rolling additive manufacturing,HARAM)技术成形GH4169D高温合金试块,并制定多种热处理制度对所成形的试块进行热处理。运用OM、SEM、EBSD、EDS、XRD、TEM等手段以及室温拉伸实验对合金的微观组织和力学性能进行观测和分析,并与常规电弧熔丝增材制造(wire and arc additive manufacturing,WAAM)方法成形的GH4169D合金进行对比。结果表明,HARAM技术中同步轧制的“微锻”作用能有效地使合金原本粗大的柱状晶发生“破碎”。与常规WAAM方法相比,采用HARAM技术所成形合金的室温抗拉强度提高(X向提高48 MPa,Z向提高90 MPa),力学性能的各向异性得到有效抑制。均匀化+固溶+双时效热处理有效消除了HARAM技术成形合金中的Laves偏析相,并促进受“微锻”作用的合金组织发生再结晶,使晶粒比未热处理时更为细小均匀,合金的综合力学性能达到最优(抗拉强度和断后延伸率X向为1366 MPa和25.0%,Z向为1354 MPa和24.6%)。

关键词：增材制造电弧微铸锻 GH4169D高温合金热处理显微组织力学性能

Discovery of Enclaves from Cenozoic PuluVolcanic Rocks in West Kunlun Mountains and Itsgeological Implications

在线全文

学校读者我要写书评

暂无评论

Journal of China University of Geosciences 2002年第1期13卷 30-34页

作者： zhang Zhaochong Xiao Xuchang Wang Jun Wang Yonginstitute of Geology , chinese academy of geological sciences, beijing 100037 institute of Geology Chinese Academy of Geological Sciences Beijing 100037

In this paper, we present the occurrence and mineral components of the enclaves firstly discovered in the Cenozoic Pulu volcanic rocks in west Kunlun Mountains, and propose that the enclave is accumulated by fractional crystallization within high-level magma chamber. In addition, the chemical compositions of its primary magma are calculated. The calculated compositions are similar to those of the Kangxiwa volcanic rocks that belong to the same volcanic belt in the Pulu volcanic region, suggesting their origin from the same source region. However, the temperatures and oxygen fugacity of magmas at high-level magma chamber decreased along with fractional crystallization.

关键词： enclave fractional crystallization volcanic rocks West Kunlun Mountains.

Petrogenesis and dating of the Kangding complex,Sichuan Province

在线全文

学校读者我要写书评

暂无评论

Science China Earth sciences 2005年第5期48卷 622-634页

作者： CHEN Yuelong 1 , LUO Zhaohua 1 , ZHAO Junxiang, LI Zhihong, zhang Hongfei & SONG Biao 3 1. Faculty of Earth sciences and Natural Resources, China University of Geosciences, beijing 100083, China 2. Faculty of Earth sciences, China University of Geosciences, Wuhan 430074, China 3. beijing SHRIMP Center, institute of Geology, chinese academy of geological sciences, beijing 100037, China 1. Faculty of Earth sciences and Natural Resources China University of Geosciences 100083 Beijing China 2. Faculty of Earth sciences China University of Geosciences 430074 Wuhan China 3. beijing SHRIMP Center Institute of Geology Chinese Academy of Geological Sciences 100037 Beijing China

An analysis of major and trace element geochemistry and SHRIMP U-Pb zircon dating of mafic, intermediate, and felsic rocks from the Mianning metamorphic complex of Si- chuan Province was conducted. One of our conclusions is that a majority of the zircons crystal- lized between 721 and 773 Ma in a magmatic regime. The complexes contain early to late Pa- leo-proterozoic relict zircons from ancient continental crust. The oldest age, 2468 Ma, may rep- resent the basement of the Yangtze block. Overgrowth zircon rims and palingenetic zircons have been observed and dated, and are believed to have formed after crystallization, during Paleozoic and Mesozoic metamorphic-anatexis. We also conclude that depletion of Nb, Ta, HREE, in a spider-diagram normalized to primitive mantle and calc-alkaline association, implies that they formed in island-arc or under-plating settings.

关键词： Kangding complex, zircons, SHRIMP, tectonic setting.