NITON矿石元素分析仪在古鲁韦镍矿上的应用效果     

邹万鹏 《吉林地质》2012,31(2):91-94

用NITON矿石元素分析仪测定圈定镍矿体地表出露边界,能基本查明矿体数量、规模、成矿规律、成矿地质条件,达到了快速评价矿床,能取得较好的找矿成果。  相似文献   

Turbulent burst around experimental spur dike     

Jennifer DUAN 《国际泥沙研究》2011,(4):471-486,523

Three-dimensional turbulent flow field was measured around an experimental spur dike by using a micro-acoustic Doppler velocimeter.Time fractions of turbulent burst events including outward interaction,ejection,inward interaction,and sweep were analyzed in each quadrant at the neighbor of the dike before and after the formation of scour hole.Over 80%of burst events near the bed have lower-order of magnitudes for both flat and scoured bed surfaces.Ejections and sweeps are prevalent before the local scour was initiated,and then outward interactions are dominant after the scour hole was formed.Conditional Reynolds stresses and high-order moments of turbulent velocities were analyzed along the thalweg.The magnitudes of u’-w’ pair were much larger than those of v’-vv’ pair in the scour zone.Among four burst events,ejections and sweeps are the higher order events contributing to the Reynolds stresses.Since sediment entrainment and transport are closely associated with turbulent bursts near bed,the development of scour hole greatly depends on the higher order event near the bed.  相似文献   

西昆仑库科西鲁克地区基性岩脉地球化学及构造意义     

范飞鹏  崔春龙  陈明勇 《火山地质与矿产》2011,(4):247-255

新疆库科西鲁克地区广泛发育基性岩脉,多呈岩墙、岩枝和小岩滴。基性岩脉岩石类型为辉长岩和辉绿岩。辉长岩属于碱性玄武岩,而辉绿岩属于过铝质碱性系列碱玄武岩与粗面玄武岩过渡型,其形成深度（浅成相）比辉长岩浅（中深成相）。区内基性岩脉形成于闭合边缘岛弧、活动陆缘造山带环境,是由幔源原生岩浆经过分异并同化混染地壳物质而形成,结晶分异是控制岩浆演化的主要因素。辉长岩中δEu具有弱的亏损。辉绿岩δEu为正异常,而C e均具弱亏损,成岩氧逸度较高,其成因与典型的I型花岗岩类相似,为壳幔混合型。辉长岩偏幔源,而辉绿岩偏壳源,可能为幔源岩浆上侵受围岩混染所致。辉长岩年龄（119 M a）要比辉绿岩年龄（46.1M a）老,辉长岩为冈底斯陆块向欧亚大陆板块碰撞拼贴过程中,逆冲挤压结束的标志,辉绿岩为大规模逆冲挤压剪切结束,青藏高原隆升初期拉张作用的产物。  相似文献   

西藏谢通门县邦弄含铁电英岩脉的地质特征及成因分析   总被引：1，自引：0，他引：1  

夏祥标  郑来林  李军敏  李再会 《矿床地质》2011,30(4):742-748

文章介绍了西藏谢通门县邦弄地区含铁电英岩脉的地质特征.电英岩脉的延伸方向大致与区内的断层平行,围岩为中粒斑状角闪黑云二长花岗岩.电英岩脉中见有不同程度的铁矿化,共有23条矿化较好的含铁电英岩脉.含铁电英岩脉中矿石矿物为赤铁矿(镜铁矿),脉石矿物为石英、电气石及少量的白云母和长石.矿石具叶片状、鳞片状结构,块状构造,矿石...  相似文献   

Geochemical Characteristics and Geological Significance of Early Permian Baya’ertuhushuo Gabbro in South Great Xing’an Range   总被引：1，自引：0，他引：1  

LIU Jianfeng  CHI Xiaoguo  ZHAO Zhi  ZHANG Xingzhou  MA Zhihong  WANG Tiefu  HU Zhaochu 《《地质学报》英文版》2011,85(1):116-129

Field geological investigation and geochemical analysis are carried out on Baya’ertuhushuo Gabbro in South Great Xing’an Range. Field investigation reveals that the gabbro is a magmatic intrusion rather than a component of an ophiolite suite as previously thought. Zircon laser ablation inductively coupled plasma mass spectroscopy (LA-ICP-MS) U-Pb dating indicates the gabbro was formed in 274–275?Ma, just as the widespread volcanic rocks of Dashizhai Formation (P1d), monzogranites and miarolitic alkali-feldspar granites in the study area. The gabbro has SiO2 content between 47.23 wt% and 50.17 wt%, high MgO and FeOT contents of 6.95–11.29 wt% and 7.32–12.24wt%, respectively, and it belongs to low-K tholeiitic series in the SiO2-K2O diagram. The Chondrite-normalized rare earth element (REE) patterns and primitive mantle-normalized spider diagrams of the gabbro are similar to those of Normal Mid-Ocean Ridge Basalt (N-MORB) except for the enrichment of large ion lithophile elements (LILE), such as Rb, Ba and K. In trace element tectonic discriminative diagrams, the samples are mainly plotted in the N-MORB field, and Zircon in?situ Lu-Hf isotopic analysis also indicates the gabbro originated from depleted mantle. Through synthetic studies of the geochemical characteristics and petrogenesis of Baya’ertuhushuo gabbro, volcanic rocks of Dashizhai Formation and granitoids in the area, it is suggested that the early Permian magmatism in the Xilinhot-Xiwuqi area formed in the tectonic setting of asthenosphere upwelling, which was caused by breaking-off of the subducted Paleo-Asian Ocean slab.  相似文献   

内蒙古北部乌日尼图地区阿仁绍布辉长岩体的形成时代、地球化学特征及成因   总被引：3，自引：0，他引：3       下载免费PDF全文

贺宏云  鞠文信  宝音乌力吉 《沉积与特提斯地质》2011,(4):70-78

本文系统地报道了内蒙古北部乌日尼图地区阿仁绍布辉长岩的主量元素、微量元素和稀土元素特征,重点讨论了阿仁绍布辉长岩体的岩石成因、原始岩浆的源区特征及其地质意义。研究结果表明,阿仁绍布辉长岩体SiO2含量为49.62%,Al2O3为17.34%,CaO为8.94%,TiO2为1.44%,P2O5为0.26%;岩石富集LILE、亏损HFSE。岩体的Mg#值（0.28～0.68,平均为0.52）较高,反映原始岩浆具幔源原生玄武岩浆特征,在上升过程中经历的结晶分异程度较低。U-Pb锆石年龄测定结果为309±2Ma,代表了阿仁绍布辉长岩体的结晶年龄,为晚石炭世。计算出石英结晶温度为928℃,斜长石结晶温度为1206℃;岩浆冷凝矿物共结晶时的深度大于10km,其结晶条件代表岩体侵位时的物理环境,是在较深的岩浆房中结晶的。阿仁绍布辉长岩具有大陆边缘弧的地球化学特征,可能反映在岩浆形成之前,地幔源区发生了俯冲交代富集作用。  相似文献   

上海湖沼平原地貌分界线上地层分布特征研究   总被引：1，自引：0，他引：1  

孙莉 《上海国土资源》2011,32(4):68-72

上海湖沼平原和滨海平原地貌类型划分应遵从地貌特征,为工程应用方便,可划分地貌亚区。地貌分界线上典型的地质剖面,为湖沼平原第一硬土层与滨海平原暗绿色硬土层属于同一地质时代提供了直接证据。由于古河道、台地等古地貌特征,造就了不同地貌及地貌亚区之间地层差异。  相似文献   

一件可能的Hf同位素测定标准锆石     

周红英  李怀坤  耿建珍  苏文博  相振群  崔玉荣  张健  李惠民 《地质学报》2013,87(4):554-564

陕西省西乡县汉南杂岩望江山岩体辉长岩中含有丰富的锆石——从600kg辉长岩样品中分选出结晶良好、内部结构简单、成因和年龄单一、Hf同位素比值均一的锆石7g,锆石粒度多为0.2-0.3mm。分别在三个不同实验室利用三种方法对该锆石样品进行了U-Pb同位素年龄测定,获得了在误差范围内完全一致的年龄：819.8 ± 2.5 Ma（LA-ICP-MS）、821.7 ± 1.7 Ma（LA-MC-ICPMS）和822.1 ± 4.5 Ma（SHRIMP）。在国内4个权威实验室对该锆石进行了Lu-Hf同位素测定,获得了在误差范围内完全一致的176Hf/177Hf同位素比值——全部421个测试点加权平均值为0.282535 ± 0.000003（2σ）。采样点岩体规模巨大,露头良好,岩石新鲜,交通方便。该锆石样品满足作为Hf同位素测定标样的各方面的指标,可能是一个比较理想的Hf 同位素测定标样。Hf同位素测定标准物质的研制,是测定获得准确可靠的Hf同位素数据的基础,具有十分重要的实用价值和科学意义。  相似文献   

Crustal structure under the Sydney Basin and Lachlan Fold Belt,determined from explosion seismic studies     

D. M. Finlayson  H. M. McCracken 《Australian Journal of Earth Sciences》2013,60(1-2):177-190

The Lachlan Fold Belt has the velocity‐depth structure of continental crust, with a thickness exceeding 50 km under the region of highest topography in Australia, and in the range 41–44 km under the central Fold Belt and Sydney Basin. There is no evidence of high upper crustal velocities normally associated with marginal or back‐arc basin crustal rocks. The velocities in the lower crust are consistent with an overall increase in metamorphic grade and/or mafic mineral content with depth. Continuing tectonic development throughout the region and the negligible seismicity at depths greater than 30 km indicate that the lower crust is undergoing ductile deformation.

The upper crustal velocities below the Sydney Basin are in the range 5.75–5.9 km/s to about 8 km, increasing to 6.35–6.5 km/s at about 15–17 km depth, where there is a high‐velocity (7.0 km/s) zone for about 9 km evident in results from one direction. The lower crust is characterised by a velocity gradient from about 6.7 km/s at 25 km, to 7.7 km/s at 40–42 km, and a transition to an upper mantle velocity of 8.03–8.12 km/s at 41.5–43.5 km depth.

Across the central Lachlan Fold Belt, velocities generally increase from 5.6 km/s at the surface to 6.0 km/s at 14.5 km depth, with a higher‐velocity zone (5.95 km/s) in the depth range 2.5–7.0 km. In the lower crust, velocities increase from 6.3 km/s at 16 km depth to 7.2 km/s at 40 km depth, then increase to 7.95 km/s at 43 km. A steeper gradient is evident at 26.5–28 km depth, where the velocity is about 6.6—6.8 km/s. Under part of the area an upper mantle low‐velocity zone in the depth range 50–64 km is interpreted from strong events recorded at distances greater than 320 km.

There is no substantial difference in the Moho depth across the boundary between the Sydney Basin and the Lachlan Fold Belt, consistent with the Basin overlying part of the Fold Belt. Pre‐Ordovician rocks within the crust suggest fragmented continental‐type crust existed E of the Precambrian craton and that these contribute to the thick crustal section in SE Australia.  相似文献   

Source process of very-long-period events accompanying long-period signals at Cotopaxi Volcano,Ecuador     

Indira Molina  Hiroyuki Kumagai  Alexander García-Aristizábal  Masaru Nakano  Patricia Mothes 《Journal of Volcanology and Geothermal Research》2008

Renewed seismic activity of Cotopaxi, Ecuador, began in January 2001 with the increased number of long-period (LP) events, followed by a swarm of volcano-tectonic (VT) earthquakes in November 2001. In late June 2002, the activity of very-long-period (VLP) (2 s) events accompanying LP (0.5–1 s) signals began beneath the volcano. The VLP waveform was characterized by an impulsive signature, which was accompanied by the LP signal showing non-harmonic oscillations. We observed temporal changes of both the VLP and LP signals from the beginning until September 2003: The VLP signal gradually disappeared and the LP signal characterized by decaying harmonic oscillations became dominant. Assuming possible source geometries, we applied a waveform inversion method to the observed waveforms of the largest VLP event. Our inversion and particle motion analyses point to volumetric changes of a sub-vertical crack as the VLP source, which is located at a depth of 2–3 km beneath the northeastern flank. The spectral analysis of the decaying harmonic oscillations of LP events shows frequencies between 2.0 and 3.5 Hz, with quality factors significantly above 100. The increased VT activity and deformation data suggest an intrusion of magma beneath the volcano. A release of gases with small magma particles may have repetitively occurred due to the pressurization, which was caused by sustained bubble growth at the magma ceiling. The released particle-laden gases opened a crack above the magma system and triggered the resonance of the crack. We interpret the VLP and LP events as the gas-release process and the resonance of the crack, respectively.  相似文献