基于RTK GPS的叶赫古城遗址形态特征     

王景发  宋春威  巴之丹 《测绘与空间地理信息》2021,44(5):89-91,93

遗址形态测量对分析遗址与环境关系、保护古遗址具有重要意义.本文利用RTK GPS对叶赫古城进行形态测量,将碎部测量的离散点进行空间插值,提取古城遗址形态示量参数,并分析遗址空间分布特征.结果表明,叶赫古城略呈椭圆形,面积64782.82 m2,城垣周长1022.38 m,地势东部略高于西部,最大坡度为55.21°,遗址向阳坡面积约为54825.71 m2,占古城遗址总面积的84.63％.叶赫古城遗址地理区位优越,三维形态科学,研究以期为叶赫古城遗迹保护和开发提供科学依据.  相似文献   

藏南米拉山地区林子宗火山岩LA-ICP-MS锆石U-Pb年龄和起源   总被引：2，自引：2，他引：0  

刘安琳  朱弟成  王青  张立雪  李世民  张亮亮  赵志丹 《地质通报》2015,34(5):826-833

大规模的林子宗火山岩呈带状展布于拉萨地体中南部地区,记录了新特提斯洋壳晚期俯冲和随后印度—欧亚大陆碰撞的重要信息,因而受到广泛关注,但迄今对区域性的林子宗火山岩仍然缺乏可靠的年龄数据约束。为此,本文对南部拉萨地体东部米拉山地区林子宗火山岩中的含角砾流纹岩样品进行了LA-ICP-MS锆石U-Pb定年和Hf同位素、全岩地球化学测试。获得了60.1±0.9Ma的锆石206Pb/238U年龄,与林周盆地典中组底部安山质岩浆活动的时代相当。测试样品以亏损中稀土元素和低的重稀土元素丰度为特征,锆石εHf(t)为正值(+8.5~+18.8),可能来源于较厚新生下地壳物质在角闪岩相/榴辉岩相过渡条件下的部分熔融。目前还很难论证呈带状分布的约60Ma林子宗火山岩稀土元素含量差异的构造含义。  相似文献   

内蒙古达茂旗满都拉地区铜矿地质特征及找矿方向探讨          下载免费PDF全文

汤超  陈军强  商志文  李志丹  刘晓雪  任军平 《地质找矿论丛》2013,28(2):210-215

满都拉地区地处达茂旗—白乃庙Cu-Au多金属成矿带,区内地层主要为古生界及中新生界,断裂构造主要为NE向、NW向及近WE向,岩浆岩以华力西晚期为主。区内铜矿床类型较丰富,有斑岩型、热液型和火山块状硫化物型。铜矿床主要产于上石炭统本巴图组及下二叠统大石寨组中,受NW向及近EW向断裂控制,与华力西岩浆活动密切相关。文章认为区域上近EW向的上石炭统—下二叠统火山岩-碎屑岩-碳酸盐岩系,是本区的最佳找矿地段,华力西晚期岩浆岩及其与地层的接触带是找矿的重要标志。  相似文献   

Geochronologic Constraints on the Magmatic Underplating of the Gangdise^ Belt in the India-Eurasia Collision： Evidence of SHRIMP II Zircon U-Pb Dating     

DONG Guochen  MO Xuanxue  ZHAO Zhidan  GUO Tieying  WANG Liangliang  CHEN Tao 《《地质学报》英文版》2005,79(6):787-794

Abstract  Abundant small mafic intrusions occur associated with granitoids along the Gangdisê magmatic belt. In addition to many discrete gabbro bodies within the granitoid plutons, a gabbro‐pyroxenite zone occurs along the southern margin of the Gangdisê belt to the north of the Yarlung Zangbo suture. The mafic intrusion zone spatially corresponds to a strong aeromagnetic anomaly, which extends ～1400 km. The mafic intrusions consist of intermittently distributed small bodies and dikes of gabbro and dolerite with accumulates of pyroxenite, olivine pyroxenite, pegmatitic pyroxenite and amphibolite. Much evidence indicates that the Gangdisê gabbro‐pyroxenite assemblage is most likely a result of underplating of mantle‐derived magma. Detailed field investigation and systematic sampling of the mafic rocks was conducted at six locations along the Lhasa‐Xigazê segment of the mafic intrusive zone, and was followed by zircon SHRIMP II U‐Pb dating. In addition to the ages of two samples previously published (47.0±1 Ma and 48.9±1.1 Ma), the isotopic ages of the remaining four gabbro samples are 51.6±1.3 Ma, 52.5±3.0 Ma, 50.2±4.2 Ma and 49.9±1.1 Ma. The range of these ages (47–52.5 Ma) provide geochronologic constraints on the Eocene timing of magma underplating beneath the Gangdisê belt at ca. 50 Ma. This underplating event post‐dated the initiation of the India‐Eurasia continental collision by 15 million years and was contemporaneous with a process of magma mixing. The SHRIMP II U‐Pb isotopic analysis also found several old ages from a few zircon grains, mostly in a range of 479–526 Ma (weighted average age 503±10 Ma), thus yielding information about the pre‐existing lower crust when underplating of mafic magma took place. It is believed that magma underplating was one of the major mechanisms for crustal growth during the Indian‐Eurasia collision, possibly corresponding in time to the formation of the 14–16 km‐thick “crust‐mantle transitional zone” characterized by Vp = 6.85–6.9 km/s.  相似文献   

Timing of Magma Mixing in the Gangdisê Magmatic Belt during the India-Asia Collision:Zircon SHRIMP U-Pb Dating     

MO Xuanxue  Dong Guochen  ZHAO Zhidan  Guo Tieying  WANG Liangliang  CHEN Tao 《《地质学报》英文版》2005,(1)

  相似文献   

Geochronologic Constraints on the Magmatic Underplating of the Gangdisê Belt in the India-Eurasia Collision: Evidence of SHRIMP II Zircon U-Pb Dating   总被引：1，自引：0，他引：1  

DONG Guochen  MO Xuanxue  ZHAO Zhidan  GUO Tieying  WANG Liangliang  CHEN Tao State Key Laboratory of Geological Processes  Mineral Resources  China University of Geosciences  Beijing  School of Earth Science  Resources  China University of Geosciences  Beijing  E-mail: moxx@cugb.edu.cn Hebei Bureau of Geology  Mineral Exploration  Development  Shijiazhuang  Hebei 《《地质学报》英文版》2005,79(6)

1 Introduction Mo et al. (2005) determined that magma mixing and mingling took place extensively in the Gangdisê magmatic belt around 50 Ma, and argued that magma mixing was genetically related to underplating of mantle-derived magmas beneath that belt. Underplating, as one of the major mechanisms for crustal growth, can occur in the environments of convergent plate boundaries, subduction and collision zones, and in intra-plate settings such as continental flood basalt provinces (Wilson, 19…  相似文献   

Inhomogeneity of the lithosphere of the Tibetan Plateau and implications for geodynamics     

Deng Jinfu  Mo Xuanxue  Luo Zhaohua  Wang Yang  Zhao Hailing  Zhao Zhidan  Su Shangguo  Yu Xuehui 《中国科学D辑(英文版)》2001,44(1):56-63

This paper discusses inhomogeneity in structure of the present lithosphere underneath the Tibetan Plateau, and deduces the P-T-t paths and deep processes during the orogenic process of post India-Asia collision through revealing the nature and sequence of geological events. A three-stage-evolution model for tectonic phases of the Tibetan Plateau has been presented. It is suggested that the formation of Parmirs-type of cool lithosphere roots represents the early phase; Nianqingtanggula-type of thinned lithosphere roots, the middle phase; and Qiangtang-type of “warm” lithosphere roots (formed by cooling of the asthenosphere), the late phase.  相似文献   

Feldspar Lead Isotopic Composition of Granitoids from the Eastern Qinling Orogenic Belt and Their Tectonic Significance     

Zhang Hongfei  Zhang Benren  Zhao Zhidan  Luo Tingchuan  Chen Yuelong Department of Geochemistry  China University of Geosciences  Wuhan  Hubei 《《地质学报》英文版》1997,71(2):171-179

This paper reports 48 feldspar lead isotope analyses from 27 granitic intrusions,which formed from the Late Proterozic to Mesozoic within the Eastern Qinling oregenic belt. Itis found that the granitic rocks of South Qinling are characterized by a strong block-effect anddepletion in U-Pb and Th-Pb, showing that these rocks came from the same lead isotopetectono-geochemical province, while those of North Qinling are characterized by higher U-Pband Th-Pb for Late Proterozoic to Early Paleozoic ones and lower U-Pb and Th-Pb forLate-Palaeozoic and younger ones in their feldspar lead isotopic composition. In the NorthQinling block, lead isotopic signatures reflect that the source of granitic magma had changedsince the Late Palaeozoic. Comparison of feldspar lead isotopic composition between SouthQinling and North Qinling shows that there is marked difference in lead isotopic compositionfor pre-Palaeozoic granitoids, indicating that the South Qinling and the North Qinling blocksbelong to different tectonic units, but the similarities in lead isotopic composition are quiteclear, which indicates that the South Qinling block had been welded with the North Qinlingblock and that the magma sources of both blocks were identical. The analysis provides directevidence for underplating of the continental crust of South Qinling beneath the North Qinlingblock in the continent-continent interaction stage of the Eastern Qinling oregenic belt.  相似文献   

巷道层测深理论曲线数值模拟及资料解释方法   总被引：3，自引：4，他引：3  

岳建华  李志聃 《煤田地质与勘探》1997,25(1):52-56

建立了层测深理论曲线正常规模拟的数学模型，结合三层和四层地电模型层测深视电阻及视电阻率理论曲线的正演计算，研究了层测深曲线特征和解释方法，同时介绍了煤矿井下层测深法的应用实例。  相似文献   

Compressional Wave Velocities in Some Volcanic Rocks at Pressure up to 4.5 GPa     

Zhou Wenge  Zhao Zhidan  Xie Hongsen 《中国地质大学学报(英文版)》1998,9(2):5

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