西秦岭岗察岩体地球化学特征及意义   总被引：1，自引：0，他引：1  

陶志华 《地质与勘探》2014,50(3):543-549

岗察岩体位于西秦岭造山带西端,该岩体形成于三叠纪中晚期,具有从中基性-酸性演化趋势。ω(SiO2)为55.15%~74.84%,Al2O3为13.12%~17.98%,K2O为1.23%~5.24%,K2O/Na2O为0.43~1.49,A/CNK为0.86~1.06,样品σ值为1.37~2.40,岩体属准铝质-弱过铝质钙碱性系列。微量元素球粒陨石标准化蜘蛛图解呈明显的右倾谱型,总体表现为Y、Yb、Zr、P、Nb、Ti(HFS)相对亏损,Rb、Th、K(LIL)富集的特征,指示岩体具有活动大陆边缘环境的特征。稀土元素(La/Yb)N为3.51~18.89,在稀土元素分配曲线上轻稀土元素富集且分异明显,重稀土元素相对亏损,Eu元素"谷"形明显,δEu为0.31~0.83,表明岩浆演化过程中有长石的结晶分异。微量与稀土元素蛛网图解形态及其组成特征还表明了岗察岩体岩浆源物质主要是由上地壳重熔演化而成。Rb-(Y+Nb)判别图解、R1-R2因子判别图解说明岩体处于西秦岭大陆活动边缘,经历了中三叠世中期西秦岭扬子地块与祁连地块之间板块碰撞造山运动。  相似文献   

东秦岭南泥湖钼（钨）矿床和秋树湾铜（钼）矿床成岩成矿特征对比研究   总被引：1，自引：0，他引：1  

张云辉 《地质与勘探》2014,50(4):700-711

东秦岭钼矿带内的南泥湖钼（钨）矿床和秋树湾铜（钼）矿床同为斑岩型矿床,地理位置相近,却在成矿类型和规模上差异显著。通过对两个矿床的矿床地质特征、成矿斑岩体的地球化学特征、成矿时代及其成矿物质来源（S同位素、流体包裹体和Re含量）进行对比分析,确定南泥湖钼（钨）矿床和秋树湾铜（钼）矿床类型均为壳幔混源型,后者成岩成矿过程有更多的幔源物质参与,并且两个矿床同时形成于秦岭造山带中生代燕山期伸展减薄的机制下,但所处构造单元（华北陆块南缘和北秦岭）不同,以上这些都导致了成矿的差异性,并为日后在东秦岭钼矿带中钼铜两类矿床的找矿工作提供参考。  相似文献   

用数值法求芹河水源地的水文地质参数     

陈静  杨海瑞  丁天生  邹杰 《地下水》2014,(2):1-3

通过对芹河水源地地区水文地质条件的分析,结合群孔抽水试验资料,建立基于有限差分法的水平面二维流理想数值模型,采用最优化方法,进行模拟计算。根据计算结果对地下水水位降深、流场分别进行拟合分析,得出所建立的的数学模型能够较为真实地刻画地下水流的特征,模型合理可靠,用于计算水文地质参数是可行的。最终得出该计算区的水文地质参数水平渗透系数K为6．588m／d,给水度μ为0．191。  相似文献   

周秦两汉时期农业灾害时空分布研究   总被引：4，自引：1，他引：4  

卜风贤 《地理科学》2002,22(4):463-467

周秦两汉时期农业灾害发生频繁，种类多样。灾害史料的灾度等级处理和统计结果表明：西周时期发生重大农业灾害8次，春秋战国时期发生重大农业灾害88次，秦汉时期发生重大农业灾害291次，农业灾害在时间分布方式表现出明显的时代特征：（1）农业灾害在年内季节分布中存在不平衡性；（2）农业灾害在年际分布中出现多个集中频发的时间区间，而且，愈到后来农业灾害集中发生的现象愈为明显，在空间分布方面，山东，山西地区是周秦两汉时期的农业重灾区。  相似文献   

Shifts of the head of Zhengguo canal dug in Qin dynasty and recent activity of the fault on north margin of the Weihe downfaulted basin     

Xuefa Yi  Yaqin Shi 《地震学报(英文版)》1992,5(4):789-795

Vertical differential movement rates of the fault on north margin of the Weihe downfaulted basin in recent 2000 years are analyzed by using the data of shifts of the head of Zhengguo canal, dug in Qin dynasty and the data of burial depths of historical relics and the data of levelling. The results show that in Ming dynasty this fault experienced the highest differential up-and-down movement, about 6.6 mm/a, while the rate became lower since Qing dynasty, about 2.6 mm/a. The high rate activity coincided with the period of high seismic activity in the Weihe downfaulted basin in the 15 – 16th centuries. The Chinese version of this paper appeared in the Chinese edition ofActa Seismologica Sinica,14, 195–200, 1992. This project is sponsored by the Chinese Joint Seismological Science Foundation.  相似文献   

频率域高密度电法在秦始皇陵地宫探测中的试验效果   总被引：2，自引：0，他引：2  

王书民  孟小红  李汝传  雷达  方慧  孙鸿雁  赵富刚 《物探与化探》2004,28(4):327-329,332

频率域高密度电法在秦始皇陵地宫探测试验中取得了明显的探测效果，探测结果不仅证实了地宫真实存在。也初步确定了地宫墓室的位置、大小、埋深及其完好性。  相似文献   

Early Cretaceous magmatism and associated polymetallic mineralization in South China: the Tiantang example     

Wei Zheng  Jing-Wen Mao  Cai-Sheng Zhao  Xiao-Fei Yu  Hai-jie Zhao  Zhi-Xia Ouyang 《International Geology Review》2018,60(11-14):1560-1580

ABSTRACT

The Tiantang Cu–Pb–Zn polymetallic deposit in western Guangdong, South China, is hosted in the contact zone between the monzogranite porphyry and limestone of the Devonian Tianziling Formation. Orebodies occur in the skarn and skarnized marble as bedded, lenses, and irregular shapes. In this study, we performed LA-ICP-MS zircon U–Pb dating, zircon trace elements, and Hf isotopic analyses on the Tiantang monzogranite porphyry closely related to Cu–Pb–Zn mineralization. Twenty-two zircons from the sample yield excellent concordia results with a weighted mean ²⁰⁶Pb/²³⁸U age of 104.5 ± 0.7 Ma, which shows that the emplacement of the monzogranite porphyry in the Tiantang deposit occurred in the Early Cretaceous. The zircon U–Pb age is largely consistent with the sulphide Rb–Sr isochron ages, indicating that both the intrusion and Cu–Pb–Zn mineralization were formed during the Early Cretaceous in South China. The ε_Hf(t) values of three inherited zircons from the monzogranite porphyry are 13.1, 11.9, and 12.9, respectively, and the two-stage Hf model ages are 1096 Ma, 1087 Ma, and 1055 Ma, respectively. Except for the three inherited zircons, all ε_Hf(t) values of zircons are negative and have a range of ?7.6 to ?3.4, with the two-stage model ages (T_DM2) of 1380–1643 Ma, which indicates the rock-forming materials were mainly derived from the partial melting of Mesoproterozoic to Neoproterozoic crust rocks, and probably included some Neoproterozoic arc-related volcanic-sedimentary materials. In this study, the monzogranite porphyry from the Tiantang deposit has calculated Ce⁴⁺/Ce³⁺ ratios of zircon ranging from 91 to 359, indicative of a more oxidized signature and significant prospecting potential for ore-related magmatism. Based on ore deposit geology, isotope geochemistry, and geochronology of the Tiantang Cu–Pb–Zn deposit and regional geodynamic evolution, the formation of Early Cretaceous magmatism and associated polymetallic mineralization in South China is believed to be related to large-scale continental extension and subsequent upwelling of the asthenosphere.  相似文献   

从陕西“周老虎”想到广州“麦船台”——评麦英豪的“广州秦汉考古三大发现”   总被引：1，自引：1，他引：0  

席龙飞 《热带地理》2009,29(1)

以陕西"周老虎"做比较,指出广州"麦船台"同为假点.上世纪70年代麦英豪定性的"秦汉造船工场遗址",30多年来始终得不到造船工程界和船史学界的认同,地理和地质学界认为这里并不存在造船和下水的条件,建筑工程和建筑考古学界则以大量出土文物证实其为南越王宫苑遗址.被国务院确定为国家重点文物保护单位的"秦造船工场遗址"既无保护,又无展出,也没有专著出版,在全国的学术界出现一片质疑和遣责声.这是麦英豪以排他性的专家"鉴研会"排斥多学科的全国性学术研讨会.文中呼吁麦英豪应正视现实,修正失误,广州的文物部门领导也应当检讨不作为的过失.  相似文献   

秦观性格试析     

程安庸 《广东海洋大学学报》2005,25(2):85-88

直率、任性、敏感和脆弱是秦观性格的基本特征,这样的性格不适合做一个政治家,却对秦观成为一个独具风格的优秀文学家起到重大作用。  相似文献   

THE UPWARPING AND DOWNWARPING STRUCTURAL SYSTEM OF MOHO—SURFACE IN CHINESE AND NEAR REGION AND THE GENETIC MECHANICS OF QINGHAI—TIBET PLATEAU TECTONIC     

Zhang Jingfa  Tang Rongyu  Chen Xuebo  Wang Enfu  Li JingshenWT  ”BX 《地学前缘》2000,(Z1)

THE UPWARPING AND DOWNWARPING STRUCTURAL SYSTEM OF MOHO—SURFACE IN CHINESE AND NEAR REGION AND THE GENETIC MECHANICS OF QINGHAI—TIBET PLATEAU TECTONIC  相似文献