Tectonic setting and petrogenesis of the Çelebi granitoid, (Kırıkkale-Turkey) and comparison with world skarn granitoids     

《Journal of Geochemical Exploration》2002,76(3)

Many studies have shown systematic correlations between the composition of plutons worldwide and the metal content of associated skarns. This is the first report of similar correlations between the composition of Çelebi granitoid and skarns of the Çelebi district in Central Anatolia, Turkey. The Çelebi district is well known for its polymetallic Fe–W and Cu vein ores. These are hosted by calcic skarn zones. Both exoskarns (pyroxene–garnet) and endoskarns (epidote–pyroxene) occur in the district formed mainly along the granitoid contacts and along the fractures within the marble. Based on mineralogy, petrology and geochemistry, two different igneous rocks were recognized in the Çelebi granitoid, referred to as leucocratic (felsic) and mesocratic (intermediate) Çelebi granitoid. The leucocratic Çelebi occurs as dominant rock type, and is classified as granite. The mesocratic Çelebi is not widespread and is classified as adamellite, tonalite, quartz monzonite and quartz monzodiorite. The mesocratic Çelebi has I-type characteristics, and have subalkaline, calc-alkaline and metaluminous characteristics like most worldwide skarn granitoids.A post-collisional tectonic setting is proposed on the basis of field evidence, the relative timing of intrusions with respect to metamorphic and obducted ophiolitic rocks and trace element geochemistry. The high abundance of La and Ce and the enrichment of V in mafic components suggest that Çelebi granitoids are formed by partial melting of mantle rocks, but have been contaminated by interaction with continental crust involving possible magma mixing processes (i.e. mixing of coexisting felsic and mafic magmas). In the district, the mesocratic type and mafic microgranular enclaves (MME) mainly within leucocratic type represent a mafic underplating magma that was mixed with and/or injected into felsic magma of the leucocratic type.The present study shows that Fe mineralization is associated with mesocratic Çelebi type, whereas W mineralization is associated with leucocratic type. Mesocratic Çelebi granitoid is significantly different from the worldwide average of plutons associated with Fe skarns. In particular, MgO vs. SiO₂, FeOt+CaO+Na₂O/K₂O vs. SiO₂, Fe₂O₃/Fe₂O₃+FeO vs. SiO₂ and V vs. Ni vary from typical values (are lower than values typical for plutons associated with Fe skarns) for plutons associated with Fe skarns. Instead, it resembles the geochemical characteristics of plutons associated with worldwide Cu and possibly Au skarns. This suggests new exploration possibilities for copper and gold in the Çelebi district.  相似文献   

2000年4月29日内乡ML4.7级地震前潢川地电异常变化     

张俊山  胡卫建  王志敏  张佩  谢健健  刘丽君 《华南地震》2002,22(3):65-70

2000年4月29日11时54分，河南省南阳市内乡县马山口镇与镇平县寺山乡之间发生一次ML4.7级地震。地震前3天，潢山台视电阻率ρs异常较为明显。分析了此次异常与内乡ML4.7级地震的关系，认为此次异常很有可能是内乡ML4.7级地震的短临前兆异常。当观测台站与震源位于同一构造带时，即便离震中较远，地电阻率对地震异常反映仍较灵敏，且与构造带同一走向的测向尤为明显。  相似文献   

利用MAPGIS编绘地质图的一些技巧     

杨志勇 《贵州地质》2003,20(2):126-126,125

计算机MAPGIS系统制图过程中，如果将大比例尺地图通过输出系统直接输出后，图面没有层次感，不能突出主题，掌握MAPGIS系统的操作技巧，对编绘各种地图，可省工省时，节约时间成本。  相似文献   

原始数据图数据自动标注方法     

赵荣军  鲁玉红  王永丽 《物探化探计算技术》2003,25(4):368-371

原始数据图是化探工作中重要的基础性图件，其数字化制图是一项费时费力的工作。利用Microsoft Visual Fox Pro、MAPGIS软件实现分析数据的自动标注，可大大地简化原始数据图制图，提高工作效率。  相似文献   

Short‐term erosion rates from a 7Be inventory balance     

Christopher G. Wilson  Gerald Matisoff  Peter J. Whiting 《地球表面变化过程与地形》2003,28(9):967-977

Detailed soil erosion studies bene?t from the ability to quantify the magnitude of erosion over time scales appropriate to the process. An inventory balance for ⁷Be was used to calculate sediment erosion in a 30·73 m² plot during a series of runoff‐producing thunderstorms occurring over three days at the Deep Loess Research Station in Treynor, Iowa, USA. The inventory balance included determination of the pre‐ and post‐storm ⁷Be inventories in the soil, the atmospheric in?ux of ⁷Be during the event, and pro?les of the ⁷Be activity in the soil following the atmospheric deposition. The erosion calculated in the plot using the ⁷Be inventory balance was 0·058 g cm^?2, which is 23 per cent of the annual average erosion determined using ¹³⁷Cs inventories. The calculated erosion from the mass balance is similar to the 0·059 g cm^?2 of erosion estimated from the amount of sediment collected at the outlet of the 6 ha ?eld during the study period and the delivery ratio (0·64). The inventory balance of ⁷Be provides a new means for evaluating soil erosion over the time period most relevant to quantifying the prediction of erosion from runoff. Copyright © 2003 John Wiley & Sons, Ltd.  相似文献   

Spatial Database Management System of China Geological Survey Extent   总被引：4，自引：0，他引：4  

ChenJianguo ChenZhijun WangQuanming FangYiping 《中国地质大学学报(英文版)》2003,14(3):250-256

The spatial database management system of China geological survey extent is a social service system. Its aim is to help the government and the whole social public to expediently use the spatial database, such as querying, indexing, mapping and product outputting. The management system has been developed based on MAPGIS6. x SDK and Visual C , considering the spatial database contents and structure and the requirements of users. This paper introduces the software structure, the data flow chart and some key techniques of software development.  相似文献   

Paleoecology of two marine oxygen isotope stage 7 sites correlated by the Sheep Creek tephra, northwestern North America     

Charles E Schweger 《Quaternary Research》2003,60(1):44-49

Pollen analysis at two sites, correlated by the presence of the 190,000 yr-old Sheep Creek tephra, documents fluctuations in vegetation and climate consistent with this date and indicates that the records span marine oxygen isotope stage 7 and the stage 6/7 transition. Dawson Cut, near Fairbanks, Alaska, provides a 5.2-m-long pollen record of interglacial boreal forest succeeded by shrub tundra and then forest/tundra. Ash Bend, Stewart River, central Yukon, provides a 9.5-m-long record of interglacial boreal forest succeeded by forest/tundra, shrub tundra, and herbaceous tundra. The replacement of forest at both sites by more open or tundra vegetation indicates warm interglacial conditions giving way to cold and arid climate. It is not clear whether stage 7 was warmer than the present. The warm-cool-warm climate oscillation evident at both sites may correlate to Lake Baikal substages 7a, 7b, and 7c. Sheep Creek tephra fell on forest/tundra vegetation.  相似文献   

卫星遥感敦煌地区地表特征参数研究   总被引：12，自引：19，他引：12  

马耀明  刘东升  王介民  黄荣辉  苏中波  高峰 《高原气象》2003,22(6):531-536

卫星遥感在研究沙漠化地区非均匀地表特征参数时有其独到的作用。本文提出了一个基于Landsat-7 TM资料推算沙漠化地区地表特征参数的方案，并把其用于中国西北地区“我国重大气候和天气灾害形成及预测理论的研究”的敦煌试验区，并且利用3个景Landsat-7 TM资料进行了分析研究，得到了一些有关沙漠化地区非均匀地表区域地表特征参数(地表反射率、地表温度、修正的土壤调整植被指数MSAVI和植被覆盖度)的新概念。  相似文献   

丽江7.0级地震地下流体异常特征   总被引：1，自引：3，他引：1  

郭绍忠  李丽清 《地震研究》1997,20(1):117-124

通过对１９９６年２月３日云南丽江Ｍｓ７．０地震前震中周围水位、水氡、水汞、泉点宏观等地下流体共７１个台项观测资料的异常及综合特征分析，初步认为震前异常数量较多，异常时间分布具有整体性、同步性、集中性的特点，但异常主要集中在短期阶段，临震异常不突出；突间分布具有集中性和非均匀性，孕震区至远场影响区的异常比例最高，震源区内为相对“盲区”，且突出而肯定的宏观异常极少；异常的时空演变特征复杂，总体没有规律  相似文献   

丽江大研镇震灾分布和地脉动测量结果之间的相关性   总被引：4，自引：2，他引：4  

蒋乐群  李康龙 《地震研究》1997,20(1):125-131

丽江７．０级地震后，大研镇被毁建筑物的地理分布呈显４条条带，伤亡人员的地理分布和上述条带重合。９１个短周期地脉动测点的观测资料表明，分布在上述条带内的大多数测点，其卓越周期大于０．３Ｓ；条带外的测点，其卓越周期一般在０．１Ｓ左右。作认为卓越周期和烈度异常之间良好的相关性，是因为地脉动卓越周期和地方震的频谱之间存在良好的相关性。  相似文献