Timing of Late Carboniferous/Permian Granite and Granite Porphyry Intrusions in the Ruhla Crystalline Complex (Central Germany), New Constraints from SHRIMP and Pb/Pb Single Zircon Dating     

A. Zeh  H. Brtz 《Chemie der Erde / Geochemistry》2002,62(4):303-316

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Late Mesoproterozoic (ca 1.2 Ga) palaeomagnetism of the Albany–Fraser orogen: no pre-Rodinia Australia–Laurentia connection     

S. A. Pisarevsky  M. T. D. Wingate  L. B. Harris 《Geophysical Journal International》2003,155(1):F6-F11

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The lamprophyres of Afyon stratovolcano,western Anatolia,Turkey: description and genesis     

Erkan Aydar  Hasan Bayhan  Alain Gourgaud 《Comptes Rendus Geoscience》2003,335(3):279-288

The Afyon stratovolcano exhibits lamprophyric rocks, emplaced as hydrovolcanic products, aphanitic lava flows and dyke intrusions, during the final stages of volcanic activity. Most of the Afyon volcanics belong to the silica-saturated alkaline suite, as potassic trachyandesites and trachytes, while the products of the latest activity are lamproitic lamprophyres (jumillite, orendite, verite, fitztroyite) and alkaline lamprophyres (campto-sannaite, sannaite, hyalo-monchiquite, analcime–monchiquite). Afyon lamprophyres exhibit LILE and Zr enrichments, related to mantle metasomatism.  相似文献   

Sr-Nd-Pb isotopes of the Early Paleozoic maficultramafic dykes and basalts from South Qinling belt and their implications for mantle composition   总被引：3，自引：0，他引：3  

Zhang ChengLi  Gao Shan  Yuan HongLin  Zhang GuoWei  Yan YunXiang  Luo JingLan  Luo JinHai 《中国科学D辑(英文版)》2007,50(9):1293-1301

Late Early Paleozoic mafic-ultramafic dykes and volcanic rocks from the South Qinling belt are char- acterized by εNd( t ) = 3.28― 5.02, (87Sr/86Sr)i= 0.70341― 0.70555, (206Pb/204Pb)i = 17.256― 18.993, (207Pb/204Pb)i= 15.505―15.642, (208Pb/204Pb)i=37.125―38.968, ?8/4=21.18―774.43, ?7/4=8.11―18.82. These charac- teristics suggest that they derived from a Middle Neoproterozoic mantle with isotopic compositions of mixed HIMU, EMII and minor EMI components. We interpret that these rocks were melting products of depleted mantle modified by subducted ancient oceanic crust and continental margin sediments along the northern margin of Yangtze block during Early Neoproterozoic.  相似文献   

秦岭造山带及相邻地块元古代基性岩墙群研究综述及相关问题探讨   总被引：32，自引：7，他引：25  

周鼎武  张成立刘良　王居里王焰  刘金平 《岩石学报》2000,16(1):22-28

基性岩墙群是重建古陆块聚合、伸展乃至裂解的关键标志之一。通过对秦岭造山带及相邻的华北地块、扬子地块元古代基性岩墙群的时空对比综 合分析表明,华北地块区发育2300Ma±和1700～1200Ma的两期基性岩墙群,分别代表了新太 古代和古元古代华北古陆块的聚合、伸展过程;扬子地块区发育800～620Ma的基性岩墙群, 反映了新元古代扬子古陆块的聚合、伸展过程。认为前震旦纪华北地块和扬子地块可能是独 立古陆块或不同古陆块的组成部分。晋宁造山作用(1100～850Ma)和澄江伸展、裂解作用(800Ma±)是可与新元古代Rodinia超大陆聚合、裂解过程进行对比、研究的重要时期。  相似文献   

Numerical simulations of the propagation path and the arrest of fluid-filled fractures in the Earth   总被引：3，自引：0，他引：3  

T. Dahm 《Geophysical Journal International》2000,141(3):623-638

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A precisely dated Proterozoic palaeomagnetic pole from the North China craton, and its relevance to palaeocontinental reconstruction   总被引：5，自引：0，他引：5  

Henry C. Halls  Jianghai Li  Don Davis  Guiting Hou  Baoxing Zhang   Xianglin Qian 《Geophysical Journal International》2000,143(1):185-203

A palaeomagnetic pole position, derived from a precisely dated primary remanence, with minimal uncertainties due to secular variation and structural correction, has been obtained for China's largest dyke swarm, which trends for about 1000 km in a NNW direction across the North China craton. Positive palaeomagnetic contact tests on two dykes signify that the remanent magnetization is primary and formed during initial cooling of the intrusions. The age of one of these dykes, based on U–Pb dating of primary zircon, is 1769.1 ± 2.5 Ma. The mean palaeomagnetic direction for 19 dykes, after structural correction, is D  = 36°, I  = − 5°, k  = 63, α ₉₅ = 4°, yielding a palaeomagnetic pole at Plat=36°N, Plong=247°E, dp  = 2°, dm  = 4° and a palaeolatitude of 2.6°S. Comparison of this pole position with others of similar age from the Canadian Shield allows a continental reconstruction that is compatible with a more or less unchanged configuration of Laurentia, Siberia and the North China craton since about 1800 Ma  相似文献   

浙江淳安早白垩世脉岩地球化学特征及成岩动力学背景   总被引：1，自引：0，他引：1  

李福林  谢瑜  周汉文  唐增才  李益龙  汪发祥  徐于晨 《矿物岩石》2011,31(3)

在浙西淳安地区江绍断裂带内发育规模较大的基性脉岩,野外地质特征显示其产状与区域构造应力场的方向基本一致,总体呈北东—南西向,且与围岩之间的界限截然。对含斑基性脉岩进行了锆石LA-ICPMS U-Pb定年和详细的岩石地球化学特征研究,其锆石206Pb/238 U加权平均年龄为135Ma±2Ma(n=18,MSWD=3.2),代表其结晶年龄,为燕山期岩浆活动的产物,岩石地球化学特征显示形成于板内拉张的环境。整体特征显示含斑基性脉岩是由基性岩墙的岩浆混合了部分围岩物质形成的。该区的含斑基性脉岩与基性岩墙群的形成可能与太平洋板块向亚洲大陆的俯冲有关,是早白垩世岩石圈发生伸展减薄所诱发的地幔物质部分熔融的产物。  相似文献   

快速筑堤技术——鲎式轻质堤坝的结构和筑堤方法     

陶松垒  傅晓航 《海洋学研究》2006,24(Z1):83-90

针对软基堤坝稳定性差,容易沉陷滑移,土石方堆不上,工期长,无法快速施工等问题,提出了鲎式轻质堤坝结构和筑堤方法,又称"松垒筑堤法".它减轻了易沉陷部位的质量,均衡堤坝荷重,增强整体稳定性,提高强度,使堤坝与地基溶为一体,消除了堤坝的不均匀沉降;是一种在软弱地基上应用仿生结构的筑堤方法.  相似文献   

Zircon U-Pb Age,Geochemical, and Sr-Nd-Pb-Hf Isotopic Constraints on the Time Frame and Origin of Early Cretaceous Mafic Dykes in the Wuling Mountain Gravity Lineament,South China     

CHEN Xiaoqing  LIU Shen  FENG Caixi  XU Jingyan  ZHAO Huibo  FENG Guangying  Ian M. COULSON  SUN Jinggui  FAN Yan 《《地质学报》英文版》2021,95(2):419-438

In view of the importance of mafic dyke swarms and their contribution to current scientific problems relating to South China, herein, we present the findings of studies on twenty–five representative mafic dykes cropping out in Hunan Province and Guangxi Zhuang Autonomous Region, within the southern Wuling Mountain gravity lineament, China. These results include new zircon LA-ICP-MS U-Pb age, whole rock geochemical, Sr-Nd-Pb isotopic, and zircon Hf isotopic data for these dykes. The dykes formed between 131.5 ± 1.2 and 121.6 ± 1.1 Ma, and have typical doleritic textures. They fall into the alkaline and shoshonitic series, are enriched in light rare earth elements(LREE), some large ion lithophile elements(LILE; e.g., Rb, Ba, and Sr), Th, U, and Pb, and are depleted in Nb, Ta, Hf, and Ti. Moreover, the dolerites have high initial87 Sr/86 Sr ratios(0.7055–0.7057), negative εNd(t) and zircon εHf(t) values(-14.8 to-11.9,-30.4 to-14.9), and relatively constant initial Pb isotopic ratios(that are EM1-like, 16.77–16.94, 15.43–15.47, and 36.84–36.92 for 206 Pb/204 Pb,207 Pb/204 Pb, and 208 Pb/204 Pb, respectively). These results indicate that the dykes were likely derived from magma generated through low-degree partial melting(1.0%–10%) of an EM1-like garnet–lherzolite mantle source. The parental magmas fractionated olivine, clinopyroxene, plagioclase, and Ti-bearing phases with negligible crustal contamination, during ascent and dyke emplacement. Several possible models have been proposed to explain the origin of Mesozoic magmatism along the Wuling Mountain gravity lineament. Herein we propose a reasonable model for the origin of these mafic dykes,involving the collision between the paleo-Pacific Plate and South China, which led to subsequent lithospheric extension and asthenosphere upwelling, resulting in partial melting the underlying mantle lithosphere in the Early Cretaceous, to form the parental magmas to the WMGL mafic dykes, as studied.  相似文献