青海祁漫塔格卡尔却卡铜多金属矿区矿床地质特征及控矿因素          下载免费PDF全文

高西平 《地质找矿论丛》2015,30(1):87-91

卡尔却卡地区是青海省重要的铁、铜、铅、锌、金多金属矿集区,具有特征明显的构造-岩浆岩带。在分析区内地层、构造、岩浆岩及接触带等控矿因素与成矿的关系的基础上,建立了找矿标志;根据区内的成矿特征,初步认为卡尔却卡多金属矿床为斑岩型矿床成矿系列,有斑岩型、夕卡岩型和蚀变岩型3种成因类型,形成斑岩-夕卡岩-热液成矿系统,成矿作用均与中-晚三叠世底侵事件有关。  相似文献   

Triggered seismicity in the Andean arc region via static stress variation by the MW = 8.8, February 27, 2010, Maule earthquake     

《Journal of South American Earth Sciences》2015

We localized crustal earthquakes in the Andean arc, between 35°S and 36°S, from December 2009 to May 2010. This research shows a seismicity increase, in a narrow longitudinal area, of more than nine times after the great M_w 8.8 Maule earthquake.The localized seismicity defines an area of ∼80 km long and ∼18 km wide and NNW to NNE trend. The M_d magnitudes varied from 0.7 to 3.1 except for two earthquakes with M_w of 3.9 and 4.5, located in the northern end of the area. The focal mechanisms for these two last events were normal/strike-slip and strike-slip respectively.During 2011, a network of 13 temporary stations was installed in the trasarc region in Malargüe, Argentina. Sixty earthquakes were localized in the study region during an 8 month period.We explored how changes in Coulomb conditions associated with the mega-thrust earthquake triggered subsequent upper-plate events in the arc region. We assumed the major proposed structures as receiver faults and used previously published earthquake source parameters and slip distribution for the Maule quake. The largest contribution to static stress change, up to 5 bars, derives from unclamping resulting consistent with co-seismic dilatational deformation inferred from GPS observations in the region and subsidence in nearby volcanoes caused by magma migration.Three different Quaternary tectonic settings–extensional, strike-slip and compressional-have been proposed for the arc region at these latitudes. We found that the unclamping produced by the Maule quake could temporarily change the local regime to normal/strike-slip, or at least it would favor the activation of Quaternary NNE to N-trending dextral strike-slip faults with dextral transtensional movement.  相似文献   

华北板块北缘中段二叠纪岩浆岩年代学、地球化学及锆石Hf同位素测试数据集          下载免费PDF全文

王文龙  刘洋  赵利刚  滕飞  杨泽黎 《中国地质》2020,47(S1):32-39

华北板块北缘中段位于华北板块与白乃庙弧的结合处，以赤峰-白云鄂博断裂为界，南、北归属不同的大地构造单元，并且具有不同的基底属性。二叠纪岩浆岩在华北板块北缘广泛分布，断裂带两侧均有出露，源区组成十分复杂，制约着对其岩石成因及构造背景的深刻认识。本文通过对横跨赤峰–白云鄂博断裂的“北柳图庙幅等4幅区调”和“乌兰布拉格幅等2幅区调”2个项目的1∶50 000区调工作，共计6个1∶50 000图幅内的二叠纪岩浆岩的年代学、地球化学及锆石Hf同位素测试数据进行整合、分析，为进一步研究华北板块北缘中段二叠纪岩浆岩的源区及构造-岩浆演化过程提供详实的数据支撑。区内二叠纪侵入岩广泛出露，岩石类型以花岗闪长岩、（石英）闪长岩及二长花岗岩为主，并含有少量的正长花岗岩。二叠纪火山岩主要分布在断裂带以南，岩性包括安山质、英安质及少量流纹质火山岩。锆石U–Pb测年表明工作区内二叠纪岩浆岩的形成时代主要为中–晚二叠世，断裂带南北两侧的岩浆岩具有截然不同的锆石Hf同位素特征，总体而言，南侧相对富集，北侧相对亏损。本数据集包括3个.xls类型文件（Zircon U–Pb dating data.xls，Zircon Hf isotope data.xls，Whole-rock geochemistry data.xls），分别记录了104件样品的地球化学数据、16件样品的锆石U–Pb测年数据和12件样品的锆石Hf同位素数据。本数据集测试样品主要在中国地质调查局天津地质调查中心实验测试中心完成，数据质量可靠。  相似文献   

Significance of adakites in petrogenesis of early Silurian magmatism at the Yudai copper deposit in the Kalatag district,NW China     

《Ore Geology Reviews》2017

Yudai is a newly discovered copper deposit associated with a porphyritic quartz diorite, in the Kalatag district of the eastern Tianshan, China. SHRIMP U-Pb dating of zircons from the diorite yielded an age of 432 ± 3 Ma. The diorite is peraluminous (ASI = 0.98–1.10), calc-alkaline to tholeiitic with high Al₂O₃ of 16.6–17.7 wt% and Mg^# of 57.4–67.4. Trace element characteristics of the diorite show it is enriched in Ba, K and Sr, and depleted in Nb, Ta, Ti, with a positive Eu anomaly and high Sr/Y and La/Yb ratios. This diorite has positive ε_Nd(t) values ranging from 6.2 to 8.4 with low initial ⁸⁷Sr/⁸⁶Sr ratios of 0.704336 to 0.704450. These geochemical and isotopic characteristics indicate that the adakite-like diorite, associated with the copper mineralization, was emplaced in an island arc setting and resulted from partial melting of subducted oceanic plate in a mantle wedge.  相似文献   

Late Triassic E-MORB-like basalts associated with porphyry Cu-deposits in the southern Yidun continental arc,eastern Tibet: Evidence of slab-tear during subduction?     

《Ore Geology Reviews》2017

It is generally believed that andesite–dacite–rhyolite suites and contemporary porphyry Cu deposits are related to subduction in active continental margin settings. However, it is still unclear which tectonic events result in the generation of porphyry Cu deposits and whether asthenospheric mantle material is involved in this process. Widespread andesitic–dacitic felsic intrusions associated with porphyry Cu deposits and rarer basalts have been identified in the Late Triassic southern Yidun arc (SYA) of eastern Tibet. However, few geochronological and geochemical data are available for these basalts, thereby hampering the development of geodynamic models for this magmatic event and the formation of related porphyry Cu deposits in the region. Here we present the first geochemical and SIMS (secondary ion mass spectrometry) zircon U–Pb data of Xiaxiaoliu basalts in the SYA. The age of the Late Triassic Xiaxiaoliu basalts (216.1 ± 2.8 Ma) is consistent with the timing of emplacement of voluminous porphyritic intrusions and the formation of Cu deposits within the SYA (peaking at 215–217 Ma). The Xiaxiaoliu basalts have E-MORB-like trace element patterns that are free of negative Nb–Ta anomalies, and have high ¹⁴³Nd/¹⁴⁴Nd_(t) values, suggesting they were sourced from asthenospheric mantle without any arc-type influence. These observations, combined with the fact that some Late Triassic mineralized porphyritic intrusions within the SYA have adakitic affinities, suggest that the basalts and other igneous rocks and associated porphyry Cu deposits within the SYA were produced by tearing of a westward-dipping slab, triggering the upwelling of asthenospheric mantle material during subduction of the Garze–Litang Ocean crust.  相似文献   

面向自然连续面群边线的协同化简方法     

张付兵  孙群  朱新铭  马京振 《地球信息科学学报》2022,24(4):631-642

自然连续面群边线化简是地形图中自然面状要素和地理国情普查数据中自然图斑自动制图综合的重要实施步骤。现有面要素边线化简算法大多以线化简算法为基础,未有效化简弯曲特征、保持面积平衡和满足图面视觉清晰性要求,且化简结果存在共享边界不一致、边线自相交和边线之间相交的拓扑问题。为此,结合自然连续面群表达特点和化简要求,本文提出一种面向自然连续面群边线的协同化简方法。首先将自然连续面群转换为拓扑数据结构组织,以待化简弧段及其相邻弧段为基础构建约束Delaunay三角网,标识化简区域;其次利用弧段双侧层次多叉树模型渐进式退化条带状弯曲、化简细小弯曲;最后自适应夸大狭窄“瓶颈”,实现边线的协同化简。以河南省某区域1:5万地形图中的植被与土质面要素进行化简实验,相较于对比方法,该方法能够有效保持自然连续面群边线化简前后的拓扑一致性、要素之间的面积平衡,充分化简目标尺度下的局部不清晰细节,化简结果精度高。  相似文献   

东亚岛弧地形横剖面与板块运动   总被引：2，自引：2，他引：2  

史学建 《海洋地质与第四纪地质》1997,17(4):91-99

通过对东亚岛弧横剖面形态的系统分析，并结合弧前的构造应力的分析，作者认为，东亚岛弧形成于板块东移的构造环境中，横剖面形态存在两种基本类型即内缓外陡型和内陡外缓型，这两种不同的横剖面具有不同的弧前应力，前者表现弧前挤压，后者表现弧前引张，这反映地貌形态与构造应力之间的密切关系。  相似文献   

Gravity Anomaly and Tectonics in the Northern Part of the North Fiji Basin - Preliminary Result of the 1994 NOFI Cruise under the NEW STARMER Programme     

Matsumoto  Takeshi  Goslin  Jean  Lagabrielle  Yves  Ruellan  Etienne  Tanahashi  Manabu 《Marine Geophysical Researches》1997,19(1):37-53

A surface ship gravity survey was carried out in the northern part of the North Fiji Basin during the NOFI cruise by the R/V l'Atalante in August-September, 1994. The two ridges inside the study area, the South Pandora Ridge and the Tripartite Ridge, present different structures and states of isostatic equilibrium in terms of gravity anomaly and its tectonic implications. The former is supported by a restoring force of an imaginary elastic plate in the crust and the latter by the Airy type isostasy. These characteristics can be derived from the difference in magmatic activity, as influenced by the difference in lithospheric structure. The latter is characterised by greater active magmatism and hydrothermalism underneath the ridge than the former. Such a difference in the magmatic activity and the horizontal scale of the shallow subsurface structure is derived from the difference in the stiffness or viscosity of the lithosphere beneath the two ridges.  相似文献   

黄河口水下斜坡波致圆弧振荡剪切破坏分析     

常方强  贾永刚 《海洋学报》2010,32(5):175-179

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大兴安岭扎兰屯地区晚奥陶世石英闪长岩体岩石地球化学特征及其地质意义   总被引：2，自引：0，他引：2  

马庆  刘建峰  迟效国 《地质通报》2018,37(5):853-862

扎兰屯音河岩体被音河水系分为南、北两部分,研究发现南、北岩体形成年代不同,选取南部岩体(称为二村岩体)进行研究。二村岩体主要由石英闪长岩-英云闪长岩组成,石英闪长岩的LA-ICP-MS锆石U-Pb年龄为444.0±4.6Ma,时代为晚奥陶世。岩石化学组成相对富钠、贫钾,Na2O/K2O值大于1(1.73~3.17),属中钾钙碱性系列。岩石富含轻稀土元素、亏损重稀土元素,富集大离子亲石元素Rb、Ba、K,显著亏损Nb、Ta、P、Ti等高场强元素。矿物组成及岩石地球化学特征指示其为I型花岗岩。岩体的形成时代、构造背景与多宝山岛弧火成岩相似,为区域多宝山岛弧西南向延伸提供了新的制约。  相似文献