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Geochemical Characteristics and Tectonic Setting of the Laohushan Basalts, North Qilian Mountains 被引量:8
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作者 QIAN Qing and ZHANG Qi Institute of Geology and Geophysics, CAS, P. O. Box 9825, Beijing 100029 《Acta Geologica Sinica(English Edition)》 SCIE CAS CSCD 2001年第4期452-457,共6页
The Ordovician Laohushan ophiolite, located in the eastern part of the North Qilian Mountains, is mainly composed of meta-peridotites, gabbros and basalts alternating with sediments. The sediments are mainly turbidite... The Ordovician Laohushan ophiolite, located in the eastern part of the North Qilian Mountains, is mainly composed of meta-peridotites, gabbros and basalts alternating with sediments. The sediments are mainly turbidites, including sandstones, siltstones, cherts etc. Major elements show that the basalts are subalkaline tholeiites and may be analogous to ocean-floor basalts. Except a few N-MORBs, most of the basalts are E-MORBs as indicated by incompatible element ratios such as (La/Ce)N, La/Sm, Ce/Zr, Zr/Y and Zr/Nb. Negative Nb anomaly is common but negative Zr, Hf and Ti anomalies are quite rare. Based on the geochemical characteristics, it is suggested that the Laohushan basalts were formed in a back-arc basin. ENd (t) of the basalts ranges between +3.0 and +8.9 and (87Sr/86Sr), ranges between 0.7030 and 0.7060, indicating a depleted mantle source which was mixed with more or less enriched mantle components. Furthermore, the petrography of the sandstones and geochemistry of the cherts suggest that the sediments were deposited near a continental margin. 展开更多
关键词 north qilian mountains Laohushan BASALTS SEDIMENTS GEOCHEMISTRY
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Rheological Properties of Mantle Peridotites at Yushigou in the North Qilian Mountains and Their Implicationsfor Plate Dynamics 被引量:10
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作者 SONG Shuguang SU Li 《Acta Geologica Sinica(English Edition)》 SCIE CAS CSCD 1998年第2期131-141,242,共12页
Abstract: This paper discusses in detail the deformation textures, glide system, petrofabrics and olivine dislocation microstructures of mantle peridotites at Yushigou in the North Qilian Mountains, northwestern China... Abstract: This paper discusses in detail the deformation textures, glide system, petrofabrics and olivine dislocation microstructures of mantle peridotites at Yushigou in the North Qilian Mountains, northwestern China. The peridotites have undergone high-pressure, high-temperature and low-strain rate plastic flow deformation. According to the dynamic recrystallized-grain size of olivine and the average spacing between the dislocation walls as well as the chemical composition of enstatite, the authors calculated the rheological parameters of the ancient upper mantle in the study area as follows: temperatures 1025–1093°C; pressures 3043–4278 MPa; depths 95–132 km; deviatoric stress 28–32 MPa; strain rates 0.2×10?14-2.13×10?14s?1 and equivalent viscosities 0.45×1020-4.65×1020 Pa ? s. These parameters suggest that the position where plastic flow took place was correspondent to the lowvelocity zone beneath the oceanic lithosphere and that oceanization characterized by middle-velocity (1–3 cm/a) sea-floor spreading took place in the North Qilian Mountains during the Early Palaeozoic. 展开更多
关键词 oceanic mantle rocks RHEOLOGY sea-floor spreading north qilian mountains
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U-Pb Zircon Dating of the Yeniutan Granitic Intrusion in the Western Sector of the North Qilian Mountains 被引量:4
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作者 MAO Jingwen ZHANG Zuoheng +3 位作者 JIAN Ping WANG Zhiliang YANG Jianmin ZHANG Zhaochong 《Acta Geologica Sinica(English Edition)》 SCIE CAS CSCD 2000年第4期781-785,共5页
Zircons from granodiorite and biotite granite in the Yeniutan granitic intrusion in the western North Qilian Mountains yielded a weighted mean 206Pb/238U apparent age of 460±3 Ma, suggesting that the intrusion or... Zircons from granodiorite and biotite granite in the Yeniutan granitic intrusion in the western North Qilian Mountains yielded a weighted mean 206Pb/238U apparent age of 460±3 Ma, suggesting that the intrusion originated during the late stage of plate subduction. Its related Ta'ergou and Xiaoliugou deposits are two of the few large tungsten deposits formed in the plate subduction environment in the world. The U-Pb dating of the zircons from the biotite granite gave a discordant lower intercept age of 183±4 Ma, which implies that the Yanshanian event was probably superimposed on the North Qilian region. 展开更多
关键词 U-Pb dating granodiorite biotite granite tungsten deposit north qilian mountains
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Geochronology and Geochemistry of the Middle Proterozoic Aoyougou Ophiolite in the North Qilian Mountains,Northwestern China 被引量:1
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作者 ZHANG Zhaochong MAO Jingwen +2 位作者 ZUO Guochao YANG Jianmin Paul T.ROBINSON 《Acta Geologica Sinica(English Edition)》 SCIE CAS CSCD 2001年第1期41-50,共10页
The Aoyougou ophiolite lies in an early Palaeozoic orogenic belt of the western North Qilian Mountains, near the Aoyougou valley in Gansu Province, northwestern China. It consists of serpentinite, a cumulate sequence ... The Aoyougou ophiolite lies in an early Palaeozoic orogenic belt of the western North Qilian Mountains, near the Aoyougou valley in Gansu Province, northwestern China. It consists of serpentinite, a cumulate sequence of gabbro and diorite, pillow and massive lavas, diabase and chert. Ages of 1840±2 Ma, 1783±2 Ma and 1784±2 Ma on three zircons from diabase, indicate an early Middle Proterozoic age. The diabases and basalts show light rare-earth element enrichment and have relatively high TiO2 contents, characteristic of ocean island basalts. All of the lavas have low MgO, Cr, Ni contents and Mg numbers indicating a more evolved character. They are believed to have been derived from a more mafic parental magma by fractionation of olivine, Cr-spinel and minor plagioclase. Based on the lava geochemistry and regional geology, the Aoyougou ophiolite was probably believed to have formed at a spreading centre in a small marginal basin. Subduction of the newly formed oceanic lithosphere in the Middle Proterozoic produced a trench-arc-basin system, which is preserved in the North Qilian Mountains. 展开更多
关键词 PROTEROZOIC OPHIOLITE GEOCHRONOLOGY GEOCHEMISTRY north qilian mountains
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From Flysch to Molasse—Sedimentary and Tectonic Evolution of Late Caledonian -Early Hercynian Foreland Basin in North Qilian Mountains 被引量:11
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作者 DuYuansheng WangJiasheng +1 位作者 HanXin ShiGR 《Journal of China University of Geosciences》 SCIE CSCD 2003年第1期1-7,共7页
The Late Caledonian to Early Hercynian North Qilian orogenic belt in no rthwestern China is an elongate tectonic unit situated between the North China p late in the north and the Qaidam plate in the south. North Qili... The Late Caledonian to Early Hercynian North Qilian orogenic belt in no rthwestern China is an elongate tectonic unit situated between the North China p late in the north and the Qaidam plate in the south. North Qilian started in the latest Proterozoic to Cambrian as a rift basin on the southern margin of North China, and evolved later to an archipelagic ocean and active continental margin during the Ordovician and a foreland basin from Silurian to the Early and Middle Devonian. The Early Silurian flysch and submarine alluvial fan, the Middle to L ate Silurian shallow marine to tidal flat deposits and the Early and Middle Devo nian terrestrial molasse are developed along the corridor Nanshan. The shallowin g upward succession from subabyssal flysch, shallow marine, tidal flat to terre strial molasse and its gradually narrowed regional distribution demonstrate that the foreland basin experienced the transition from flysch stage to molasse stag e during the Silurian and Devonian time. 展开更多
关键词 north qilian mountains Silurian DEVONIAN FLYSCH MOLASSE foreland basin.
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Integrated P-T Paths of the High-Pressure Rocks and Their Tectonic Implications for the Mountain-Building of the North Qilian, China
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作者 陈维民 黄永清 +6 位作者 饭冢义之 罗清华 吴汉泉 宋述光 杨经绥 许志琴 杨宏义 《Acta Geologica Sinica(English Edition)》 SCIE CAS CSCD 2002年第1期44-62,共19页
After the integration of petrographic study, geothermobarometry and Gibbs method, the synthetic P-T paths for the rocks from different geological profiles in the North Qilian, China, have been derived. The composite P... After the integration of petrographic study, geothermobarometry and Gibbs method, the synthetic P-T paths for the rocks from different geological profiles in the North Qilian, China, have been derived. The composite P-T paths from different methods indicate that all the high-pressure rocks in the Qilian area recorded P-T paths with clockwise loops starting at the blueschist facies, later reaching peak metamorphism at the blueschist facies, eclogite fades or epidote-amphibolite facies and ending up with the greenschist facies. The incremental Ar-Ar dating shows that the plateau ages for the high-pressure rocks range from 410 to 443 Ma. The plateau ages could be used as a minimum age constraint for the subduction that resulted in the formation of these high-pressure rocks in the Qilian area. It is proposed that the late-stage decompressional and cooling P-T paths with ends at the greenschist facies for these high-pressure rocks probably reflect the uplift process which could occur after shifting the arc-trench tectonic system to the system of continental orogenic belts. The retrograde paths for the high-pressure rocks in the North Qilian tectonic belt are characterized by dramatic decompression with slight cooling, which suggests very rapid exhumation. Petrography supports that the mountain-building for the Qilian mountain range could undergo a very fast process which caused rapid uplift and denudation. 展开更多
关键词 PETROLOGY integrated P-T path high-pressure rocks mountain-building of north qilian China
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Paleosubmarine Volcanism and Mineralization from North Qilian Mountains 被引量:2
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作者 Xia Linqi Xia Zuchun Ren Youxiang Xu Xueyi Peng Ligui Institute of Geology and Mineral Resources, CAGS, Xi ’an 710054 《Journal of Earth Science》 SCIE CAS CSCD 1999年第1期38-41,共4页
This paper summarizes the history of tectono magmatic evolution, the types and backgrounds of mineralization prior to the orogenic period of North Qilian Mountains. It points out that: during the process of Paleozoic... This paper summarizes the history of tectono magmatic evolution, the types and backgrounds of mineralization prior to the orogenic period of North Qilian Mountains. It points out that: during the process of Paleozoic ocean basin opening and closing, the large scale marine volcanism and massive sulfide deposits controlled by sea floor hydrothermal circulation systems are the two sharpest features in the geological developing history of the orogenic belt, which are also the most two important aspects related to each other and should be given a special attention in the geological studies in the region. 展开更多
关键词 paleosubmarine volcanism massive sulfide deposit north qilian mountains.
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Zircon U-Pb SHRIMP ages of eclogites from the North Qilian Mountains in NW China and their tectonic implication 被引量:47
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作者 SONGShuguang ZHANGLifei +3 位作者 NIUYaoling SONGBiao ZHANGGuibing WANGQianjie 《Chinese Science Bulletin》 SCIE EI CAS 2004年第8期848-852,共5页
Cathodoluminescence (CL) imaging and ion microprobe (SHRIMP) U-Pb dating were carried out for zircons from eclogites in the North Qilian Mountains. The results show weighted mean ages of 463 6 Ma and 468 13 Ma for two... Cathodoluminescence (CL) imaging and ion microprobe (SHRIMP) U-Pb dating were carried out for zircons from eclogites in the North Qilian Mountains. The results show weighted mean ages of 463 6 Ma and 468 13 Ma for two samples, respectively. These ages are the earliest record of Caledonian high-pressure metamorphism in the North Qilian Mountains, and they may represent the timing of eclogite-facies metamorphism when the oceanic crust was subducted to mantle depths in this orogenic belt. 展开更多
关键词 高压变质 榴辉岩 锆石年代学 祁连山北部 U-PB SHRIMP
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Indian Ocean-MORB-type isotopic signature of Yushigou ophiolite in North Qilian Mountains and its implications 被引量:22
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作者 HOU Qingye1,2, ZHAO Zhidan1,2, ZHANG Hongfei3, ZHANG Benren3 & CHEN Yuelong2 1. State Key Laboratory of Geological Processes and Mineral Resources, China University of Geosciences, Beijing 100083, China 2. School of Earth Science and Mineral Resources, China University of Geosciences, Beijing 100083, China 3. Faculty of Earth Sciences, China University of Geosciences, Wuhan 430074, China 《Science China Earth Sciences》 SCIE EI CAS 2006年第6期561-572,共12页
In order to explore the disputed issue concerning the tectonic affinity ofthe ancient ocean mantle of North Qilian Mountains (NQM), geochemical and Sr, Nd, Pb isotopiccompositions of pillow basalts of the Yushigou Oph... In order to explore the disputed issue concerning the tectonic affinity ofthe ancient ocean mantle of North Qilian Mountains (NQM), geochemical and Sr, Nd, Pb isotopiccompositions of pillow basalts of the Yushigou Ophiolite (YSGO) suite from NQM have been analyzedsystematically. The pillow basalts exhibit tholeiitic characteristics, with flatchondrite-normalized REE patterns ((La/Yb)_N = 0.98—1.27). They display no Nb, Ta, Zr, Hf negativeanomalies, and show MORB features in 2Nb-Zr/4-Y and Ti/100-Zr-YX3 tectonic discrimination diagrams.These results indicate that the Yushigou ophiolite is most likely to be formed in a mid-ocean ridgeor mature back-arc basin. Their isotopic data show a relatively broad and enriched ^(87)Sr/^(86)Sr(0.70509 — 0.70700), restricted ^(143)Nd/^(144)Nd (0.512955-0.512978). Pb isotopes are in the rangeof ^(206)Pb/^(204)Pb (18.054-20.562), ^(207)Pb/^(204)Pb (15.537-15.743) and ^(208)Pb/^(204)Pb(38.068-38.530). These isotopic data imply that the basalts originated from the depleted mantle(DMM), with the involvement of enriched mantle components (mainly EMII). Geochemical comparisonsbetween the basalts in YSGO and the MORB-type basalts of ophiolite suites occurring in the knownancient Tethyan tectonic domain indicate that the ancient oceanic mantle represented by YSGO suiteforming in early Paleozoic in the North Qilian Moutains is very similar to the Tethyan mantle inboth trace elements and isotopic compositions. The North Qilian Mountains should be a part of theTethyan tectonic domain in early Paleozoic. This further implies that the Tethyan tectonic domaincan be deduced to early Paleozoic in the study area, which will be helpful to discussing thetectonic affinity and evolution of the North Qilian Mountains. 展开更多
关键词 geochemistry INDIAN Ocean-MORB-type ISOTOPIC signatures TETHYAN TECTONIC domain Yushigou ophiolite north qilian mountains.
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Determination of properties of Proterozoic continental flood basalts of western part from North Qilian Mountains 被引量:14
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作者 夏林圻 夏祖春 +3 位作者 赵江天 徐学义 杨合群 赵东宏 《Science China Earth Sciences》 SCIE EI CAS 1999年第5期506-514,共9页
Proterozoic volcanic rocks of the western part from the North Qilian Mountains are the products of continental rift volcanism, belonging to continental flood basalts, the petrogeochemistry of which apears to suggest t... Proterozoic volcanic rocks of the western part from the North Qilian Mountains are the products of continental rift volcanism, belonging to continental flood basalts, the petrogeochemistry of which apears to suggest that they are derived from sub-lithospheric mantle plume sources, but that they also show evidence of continental lithosphere components involvement. Their formation is the consequences of plume-lithosphere interactions and is precursive to the opening of the North Qilian Early-Paleozoic ocean basin. 展开更多
关键词 Zhulongguan Group-Jintieshan Group CONTINENTAL flood BASALTS petrogeochemistry PROTEROZOIC north qilian mountains.
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CH_4-rich fluid inclusions in the Yushigou mantle peridotite and their implications, North Qilian Mountains, China 被引量:10
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作者 SU Li, SONG Shuguang and WANG ZhihaiXi’an Institute of Geology and Mineral Resources, CAGS, Xi’an 710054, China 《Chinese Science Bulletin》 SCIE EI CAS 1999年第21期1992-1995,共4页
Studies were carried out on the early phase of fluid inclusions which occur in residual olivines in harzburgite from the Yushigou ophiolitic mantle peridotite, the North Qilian Mountains. Components of these inclusion... Studies were carried out on the early phase of fluid inclusions which occur in residual olivines in harzburgite from the Yushigou ophiolitic mantle peridotite, the North Qilian Mountains. Components of these inclusions, analyzed by micro laser Raman spectroscopy, are dominantly CH4 (70%-95%) with minor H2, N2, H2S,CO2,C2H4,C2H6, and C3H6, but 展开更多
关键词 CH4-rich fluid mantle PERIDOTITE north qilian mountains.
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Forming age and tectono-petrogenises of the Jiugequan ophiolite in the North Qilian Mountain,NW China 被引量:34
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作者 XIA XiaoHong SONG ShuGuang 《Chinese Science Bulletin》 SCIE EI CAS 2010年第18期1899-1907,共9页
The Jiugequan ophiolite is one of the representative ophiolite fragments in the Early Paleozoic orogenic belt of the North Qilian Mountain.It has been drawn much attention and extensively studied in recent years.In th... The Jiugequan ophiolite is one of the representative ophiolite fragments in the Early Paleozoic orogenic belt of the North Qilian Mountain.It has been drawn much attention and extensively studied in recent years.In this study,ion microprobe(SHRIMP) U-Pb dating was carried out for zircons from isotropic gabbro from the Jiugequan ophiolite.Eighteen analyses yield a relatively consistent apparent 206Pb/238U ages from 480 to 508 Ma with a weighted mean age of 490±5 Ma(MSWD=1.06),which is believed to be the crystallization age of the gabbro and thus the forming age of the Jiugequan ophiolite.Major and trace element geochemical study indicates that the diabase-basalts from the Jiugequan ophiolite have N-MORB and E-MORB characteristics with some subduction-related signatures.The petrological,geochemical and chronological data enable us to conclude that the Jiugequan ophiolite is most likely to be formed at a spreading center of back-arc basin during the early Ordovician,while the ancient Qilian oceanic plate subducted northwards.The acquisition of forming age and determination of tectonic setting for Jiugequan ophiolite provide significant constraints on the evolution of intra-oceanic subduction system in the North Qilian orogenic belt during the Early Paleozoic era. 展开更多
关键词 北祁连山 形成时代 蛇绿岩 构造 北祁连造山带 中国 净重 板块俯冲
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Apatite Fission Track Constraints on the Pattern of Faulting in the North Qilian Mountain 被引量:2
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作者 李清洋 潘保田 +3 位作者 胡小飞 胡振波 李富强 杨顺智 《Journal of Earth Science》 SCIE CAS CSCD 2013年第4期569-578,共10页
The Qilian (祁连) Mountain is an active orogenic belt located at the northeastern margin of the Tibetan Plateau. During the process of continuous convergence between Indian and Eurasian plates, the Qilian Mountain g... The Qilian (祁连) Mountain is an active orogenic belt located at the northeastern margin of the Tibetan Plateau. During the process of continuous convergence between Indian and Eurasian plates, the Qilian Mountain grow correspondingly by means of reaction of old faults and generation of new ones. Here we present apatite fission-track data along a river profile crossing three minor fault (the Minle (民乐)-Damaying (大马营) fault, the Huangcheng (皇城)-Taerzhuang (塔尔庄) fault and the Kangningqiao (唐宁桥) fault) which compose the North Qilian fault (NQF) to test the timing and pat- terns of the fault activities. Apatite fission-track (AFT) results indicate that these minor faults expe- rienced two active phases in the Cretaceous and the Oligocene-Miocene. Further research indicate that the initiation timing of faulting became younger northward in both active periods and the later phase probably more active than the former phase. These tectonic activities might be highly related to the docking of the Lhasa Block to the south in the Cretaceous and uplift and expansion of the Tibetan Pla- teau in the Cenozoic. 展开更多
关键词 north qilian Mountain AFT fault activity.
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Petrogenesis of Aoyougou high-silica adakite in the North Qilian orogen,NW China:Evidence for decompression melting of oceanic slab 被引量:17
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作者 YuXiao Chen XiaoHong Xia ShuGuang Song 《Chinese Science Bulletin》 SCIE EI CAS 2012年第18期2289-2301,共13页
A trondhjemitic body occurs in the Aoyougou area,the western part of the North Qilian orogen.It is geochemically characterized by high SiO 2,Na 2 O (high Na/K),elevated Sr/Y and (La/Yb) N,positive Sr anomaly,relativel... A trondhjemitic body occurs in the Aoyougou area,the western part of the North Qilian orogen.It is geochemically characterized by high SiO 2,Na 2 O (high Na/K),elevated Sr/Y and (La/Yb) N,positive Sr anomaly,relatively enriched large ion lithophile elements (LILEs) and light rare earth elements (LREEs),and depleted Nb,Ta,Ti,resembling the high-silica adakite.Zircon U-Pb SHRIMP dating yields a weighted mean age of 438±3 Ma.This age is significantly younger than eclogitization ages of 460-490 Ma in the North Qilian orogen,suggesting that formation of the adakite postdates the subduction of oceanic crust in association with closure of the ancient Qilian Ocean.Whole-rock Sr and Nd isotopic analyses give initial ratios of I Sr =0.7044 0.7047 and Nd (t)=3.0 4.1,indicating that they are derived from partial melting of the juvenile oceanic crust.In view of the tectonic evolution of the North Qilian orogen,the high-silica adakite was probably derived from decompression melting of the exhumed eclogite at the depth of ~60 km. 展开更多
关键词 北祁连造山带 大洋地壳 部分熔融 埃达克岩 稀土元素地球化学特征 高硅 中国西北 减压
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祁连山北坡沙尘天气气溶胶特征的飞机观测 被引量:1
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作者 奚立宗 把黎 +2 位作者 庞朝云 李宝梓 黄山 《应用气象学报》 CSCD 北大核心 2024年第3期311-322,共12页
了解沙尘天气下气溶胶的垂直分布特征对于进一步认识气溶胶-云相互作用及其天气、气候效应至关重要。基于2023年9月6日沙尘天气下的飞机观测数据,分析祁连山北坡沙尘气溶胶的垂直分布特征。结果表明:此次沙尘天气是在高空锋区及地面冷... 了解沙尘天气下气溶胶的垂直分布特征对于进一步认识气溶胶-云相互作用及其天气、气候效应至关重要。基于2023年9月6日沙尘天气下的飞机观测数据,分析祁连山北坡沙尘气溶胶的垂直分布特征。结果表明:此次沙尘天气是在高空锋区及地面冷高压的共同作用下形成。受沙尘天气影响,气溶胶粒径谱宽增宽;气溶胶数浓度较背景可上升约2~3倍,且气溶胶数浓度大值区呈悬垂状态分布,粒子数浓度大值层位于4000~4500 m和3000~4000 m高度;对沙尘气溶胶数浓度贡献最大的细粒子和粗粒子粒径分别为1.2~1.8μm和6.5~16.6μm,且气溶胶数浓度的增大在粗粒子段更为明显。气溶胶来源及输送层、以及气象要素垂直分布演变在气溶胶垂直分布及谱分布中发挥了重要作用。 展开更多
关键词 沙尘气溶胶 飞机观测 祁连山北坡 垂直分布
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北祁连玉石沟蛇绿岩形成于晚震旦世的SHRIMP年龄证据 被引量:120
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作者 史仁灯 杨经绥 +1 位作者 吴才来 J.WOODEN 《地质学报》 EI CAS CSCD 北大核心 2004年第5期649-657,共9页
玉石沟蛇绿岩位于青藏高原东北缘的北祁连山中部 ,由地幔橄榄岩、堆晶辉长岩、辉绿岩、枕状熔岩以及夹杂在其中的硅质岩组成。地幔橄榄岩主要是方辉橄榄岩 ,其主要氧化物成分较为单一 ,具 L REE富集、Eu亏损的 U形 REE配分模式 ,亏损强... 玉石沟蛇绿岩位于青藏高原东北缘的北祁连山中部 ,由地幔橄榄岩、堆晶辉长岩、辉绿岩、枕状熔岩以及夹杂在其中的硅质岩组成。地幔橄榄岩主要是方辉橄榄岩 ,其主要氧化物成分较为单一 ,具 L REE富集、Eu亏损的 U形 REE配分模式 ,亏损强不相容元素 ;枕状熔岩具典型 MORB特征 ,在构造判别图解上位于 MORB和 IAT区域 ,指示蛇绿岩可能形成于类似于洋中脊的构造环境 ,并受到火山弧岩浆作用的影响。堆晶辉长岩具明显的 Eu正异常 ,其锆石离子探针 (SHRIMP) 2 0 6 Pb/2 38U加权平均年龄为 5 5 0± 17Ma,Th/U值为 0 .5 3~ 1.85 ,大于0 .2 3,为岩浆成因锆石 ,其年龄代表辉长岩的成岩时代 ,推断玉石沟蛇绿岩形成于晚震旦世。 展开更多
关键词 蛇绿岩 SHRIMP 辉长岩 北祁连 熔岩 地幔 橄榄岩 晚震旦世 硅质岩 青藏高原
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阴山北麓地区植被覆盖动态时空分析 被引量:30
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作者 刘亚玲 潘志华 +1 位作者 范锦龙 郑大玮 《资源科学》 CSSCI CSCD 北大核心 2005年第4期168-174,共7页
阴山北麓地区是我国典型的生态脆弱带及北方重要的生态屏障,监测其植被覆盖变化是研究该地区以及农牧交错带对全球变化响应问题的基础与切入点.本文基于1998年~2003年该地区SPOT-4/VEGETATION的S10数据集,通过分析年均NDVI、年最大NDVI... 阴山北麓地区是我国典型的生态脆弱带及北方重要的生态屏障,监测其植被覆盖变化是研究该地区以及农牧交错带对全球变化响应问题的基础与切入点.本文基于1998年~2003年该地区SPOT-4/VEGETATION的S10数据集,通过分析年均NDVI、年最大NDVI、NDVI变化值、NDVI变化率等指标,得出:①全区年最大NDVI与全区年均NDVI具有可替代性;②1999年~2001年的全区年最大NDVI连续减少,而后两年连续增加,2003年情况与1998年基本持平;③林地、草地和耕地的年最大NDVI和年内变化幅度都是耕地>林地>草地,而6年间年最大NDVI变化幅度是林地>耕地>草地.2003年林地和耕地的年最大NDVI较1998年分别有微弱和较显著增加,而草地仍有较显著减少;④2001年较1998年的年最大NDVI除达茂旗中部、多伦县东部和商都县东南部少数地区有所改善外,其他大部地区呈现严重退化和显著减少;2003年较2001年除达茂旗西北部、多伦县东部零星地区呈现退化和减少外,其他所有地区都有中高度的改善和显著增加;2003年较1998年西北部有中度退化和显著减少,其他地区退化与改善并存. 展开更多
关键词 北麓地区 时空分析 阴山 2003年 1998年 2001年 动态 植被覆盖变化 NDVI变化 变化幅度 生态脆弱带 农牧交错带 1999年 生态屏障 全球变化 达茂旗 多伦县 西北部 林地 草地 耕地 退化 切入点 数据集 S10 变化率 替代性 东南部
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北祁连西段熬油沟辉长岩的锆石SHRIMP U-Pb年龄及地质意义 被引量:53
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作者 相振群 陆松年 +3 位作者 李怀坤 李惠民 宋彪 郑健康 《地质通报》 CAS CSCD 北大核心 2007年第12期1686-1691,共6页
从北祁连熬油沟辉长岩中选出的锆石的外部形态、内部结构单一。SHRIMP测年共测定8个点,每个点的Th/U值都非常高,大都在0.8以上。8个点的206Pb/238U表面年龄在误差范围内完全一致,加权平均值为503.7Ma±6.4Ma,这一结果与前人在同一... 从北祁连熬油沟辉长岩中选出的锆石的外部形态、内部结构单一。SHRIMP测年共测定8个点,每个点的Th/U值都非常高,大都在0.8以上。8个点的206Pb/238U表面年龄在误差范围内完全一致,加权平均值为503.7Ma±6.4Ma,这一结果与前人在同一地点采集的辉绿岩墙样品的锆石SHRIMP U-Pb测年结果有较大的差异。结合研究区内已有的研究成果认为:①熬油沟地区的辉长辉绿岩形成于早古生代,并不是中元古代早期。②辉长岩中的锆石成因单一,其测试年龄结果的地质意义明确;而同源岩浆侵入体的辉绿岩往往容易从围岩中捕获大量锆石,使得锆石成因复杂,年龄测试结果复杂。因此,与辉绿岩相比,辉长岩锆石SHRIMP U-Pb年代学研究可以获得更为可靠的、地质意义明确的年龄信息。 展开更多
关键词 北祁连山 熬油沟 辉长岩 锆石SHRIMP U-PB年龄
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秦岭北麓主要河流的水质现状调查与评价 被引量:23
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作者 肖玲 王书转 +2 位作者 张健 王利军 任桂镇 《干旱区资源与环境》 CSSCI CSCD 北大核心 2008年第1期74-78,共5页
调查了秦岭北麓西自宝鸡东至潼关的10县区的28条河流,利用单污染指数法和综合污染指数法进行了评价。研究结果表明:有56.10%的河段受到不同程度的污染,其中水质严重污染的河段占7.32%;中度污染的河段占14.63%;轻污染的河段占34.15%。共... 调查了秦岭北麓西自宝鸡东至潼关的10县区的28条河流,利用单污染指数法和综合污染指数法进行了评价。研究结果表明:有56.10%的河段受到不同程度的污染,其中水质严重污染的河段占7.32%;中度污染的河段占14.63%;轻污染的河段占34.15%。共有43.90%的河段水质较好,其中水质尚清洁的河段占34.15%;水质清洁的河段占9.76%。不同区县的污染特点不同。宝鸡市陈仓区和渭滨区的河段水体较清洁;西安市所辖户县、周至县、长安区主要以有机污染为主;渭南市所辖潼关、华阴和华县的有机污染和金属污染及氟污染都很严重。 展开更多
关键词 秦岭北麓 河流 水质 评价
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北祁连山西段剪切带型金矿床成矿流体特征 被引量:29
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作者 毛景文 张作衡 +2 位作者 杨建民 王志良 张招崇 《矿床地质》 CAS CSCD 北大核心 2000年第1期9-16,共8页
北祁连山西段金矿床以剪切带型为主 ,控矿的主导因素是剪切构造和成矿流体。对寒山、鹰嘴山和珠龙等代表性矿床的流体包裹体的研究表明 ,产于剪切带中金矿床的成矿流体具有中低温、低密度和低盐度等特点 ,包裹体中气体和液体 CO2 / H2 ... 北祁连山西段金矿床以剪切带型为主 ,控矿的主导因素是剪切构造和成矿流体。对寒山、鹰嘴山和珠龙等代表性矿床的流体包裹体的研究表明 ,产于剪切带中金矿床的成矿流体具有中低温、低密度和低盐度等特点 ,包裹体中气体和液体 CO2 / H2 O比值较高。稳定同位素研究结果表明 ,不同矿床的成矿流体来源不尽相同 ,鹰嘴山矿床和寒山矿床成矿流体来源以深部流体为主 。 展开更多
关键词 金矿床 成矿流体 成矿机制 北祁连山 剪切带
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