安徽凤阳和张八岭地区含金石英脉的⁴⁰Ar/³⁹Ar年龄及其地质意义   总被引：3，自引：1，他引：3  

应汉龙  刘秉光 《矿床地质》2002,21(3):240-245

用快中子活化法测定了安徽凤阳和张八岭地区朱顶、毛山和上成3个金矿床第一阶段晚期和第二阶段的含金石英脉,石英的阶段加热40Ar/39Ar坪年龄值域为(116.1±0.6～118.3±0.5)Ma,分别与其最小视年龄和等时线年龄接近.坪年龄、最小视年龄和等时线年龄3种年龄值域为(113.4±0.4～118.3±0.5)Ma,可以作为石英的形成年龄域. 根据含金石英脉和围岩的空间关系,该年龄值域作为石英脉金矿的形成年龄是合理可靠的.金矿床形成于早白垩世阿普特期,与此时郯庐断裂带略带右行走滑正断层活动一致.  相似文献   

燕山东段地区与花岗岩有关的几个问题探讨     

饶玉学 《矿产与地质》2002,16(6):327-331

详细研究了燕山东段地区花岗岩类的侵入时代、产出形式和成因类型 ,指出该区与花岗岩有关的三个金属成矿系列。  相似文献   

柴北缘绿梁山地区辉长岩的锆石U-Pb年龄及意义   总被引：11，自引：0，他引：11  

袁桂邦  王惠初  李惠民  郝国杰  辛后田  张宝华  王青海  田琪 《华北地质》2002,25(1):36-40

柴达木盆地北缘绿梁山地区的辉长岩侵入到古生代滩间山群及超基性岩中 ,地球化学、微量元素、稀土元素显示出源幔特征。选自其中的锆石明显具岩浆型锆石特点 ,4个单颗粒锆石U -Pb同位素年龄均为谐和年龄 ,2 0 6 Pb 2 38U表面年龄统计权重平均值为 (496 .3± 6 .2 )Ma ,代表了该岩体的结晶年龄 ,从而间接地否定了本区滩间山群的时代为晚奥陶世 -志留纪的认识。辉长岩与滩间山群是柴北缘活动大陆边缘火山岛弧的组成部分。此类岩体同位素地质年龄的确定对柴北缘榴辉岩、滩间山群时代及大地构造性质的重新认识具有重要意义  相似文献   

造山带岩石圈化学结构平面图的编制——以秦岭—大别造山带为例          下载免费PDF全文

侯广顺  韩吟文  路凤香 《甘肃地质》2002,(2):87-92

国内外岩石圈化学组成的编图研究还处于探索阶段。笔者从岩石圈化学结构的思路出发 ,提出了编图的 3个地球化学指标 (铅同位素组成、T2DM 和同位素年代学 )和表示方法。以秦岭—大别造山带为例 ,同位素组成图可以反映构造分区和地壳生长历史 ,对造山过程和深部壳幔相互作用也有明确的显示 ;结合地质年代学的资料 ,化学结构平面图具有反映时空演化四维信息的能力。  相似文献   

Sm-Nd ISOTOPIC AGE OF LAMPROPHYRES IN THE GEZHEN GOLD-BEARING SHEAR ZONE ON HAINAN ISLAND AND ITS GEOLOGICAL IMPLICATIONS     

XU De-ru LIANG Xin-quan CHEN Guang-hao HUANG Zhi-long 《大地构造与成矿学(英文版)》2002,(2):76-81

Sm-Nd isotopic compositions of eight lamprophyre samples, which come from the Gezhen gold-bearing shear zone on western Hainan Island, are measured. The Sm-Nd isochron age is 495.98±13.14 Ma, (143Nd/144Nd) 0=0.512094, εNd(t) ranges from +1.80 to +2.00 and TDM from 982 Ma to 1196 Ma (average: 1060 Ma). The authors point out that the whole-rock Sm-Nd isochron age (495.98 ± 13.14 Ma) really represents the petrogenetic age of lamprophyre and the time of magmatism during subsequent subduction.  相似文献   

Timing of Fracture Formation and Duration of Mineralization at the Hishikari Deposit, Southern Kyushu, Japan     

Ryota Sekine    Eiji Izawa  Koichiro Watanabe 《Resource Geology》2002,52(4):395-404

Abstract. The Hishikari epithermal gold deposit consists of the Honko-Sanjin zone and Yamada zone. On the basis of observed crosscutting relationships of veins, vein system in the Hishikari deposit was classified into the early and late veins. They differ from orientation, width, control by unconformity, the amount of displacement and structural features, but have similarity in gold grade and Au/Ag ratios. K-Ar ages are presented for the classified veins to clarify timing of fracturing and duration of mineralization.
Age determination revealed that the early veins in the Honko-Sanjin zone range from 0.86 to 1.11 Ma and that the late veins range from 0.73 to 0. 84 Ma. The economically most important mineralization in the Hishikari deposit occurred around 0.90 Ma in a very short period (about 0.05 million years).
The distribution of mineralization age in the whole Hishikari deposit, occurrences of slickensides and ground water temperatures imply that mineralization lasted longer in the southern part of the deposit. As compared the early veins with late veins, structural changes including width, strike, dip and vein characteristics occurred at around 0.85 Ma.  相似文献   

Metallogenesis of Porphyry Cu Deposits of the Western Luzon Arc, Philippines: K-Ar ages, SO₃ Contents of Microphenocrystic Apatite and Significance of Intrusive Rocks     

Akira IMAI 《Resource Geology》2002,52(2):147-161

Abstract: K–Ar ages of the following porphyry Cu deposits in the western Luzon arc are determined: Lobo-Boneng (10.50.4 Ma), Santo Niño (9.50.3 Ma), Black Mountain (2.10.1 Ma), Dizon (2.50.2 Ma) and Taysan (7.30.2 Ma). Microphenocrys-tic apatite in the late Cenozoic intermediate to silicic intrusions associated with porphyry Cu deposits in the western Luzon arc contains sulfur as SO₃ detectable by electron probe microanalyzer. Sulfur is supposed to have been accommodated dominantly as oxidized species in oxidizing hydrous magmas that generated porphyry Cu deposits. Likewise, such high SO₃ contents in microphenocrystic apatite are common characteristics of the intermediate to silicic magmatism of the western Luzon arc, from tonalitic rocks of the Luzon Central Cordillera of about 15 Ma to an active magmatism at Mount Pinatubo. Thus, the western Luzon arc has been generating porphyry Cu mineralization associated with oxidizing hydrous intermediate to silicic magmatism related to eastward subduction, since Miocene to the present day. Intermediate to silicic rocks since 15 Ma to present-day western Luzon arc generally show high whole-rock Sr/Y ratio ranging from 20 to 184. However, porphyry Cu deposit is not necessarily related to the rocks that show higher Sr/Y ratios compared to the other barren rocks in the western Luzon arc. The characteristics of the intermediate to silicic magma associated with porphyry Cu deposit are not attributed to the composition of the source material of the magma, but to the properties defined by the high activity of oxidized species of sulfur in the fluid phase that is encountered during the generation of intermediate to silicic magmas.  相似文献   

湖北牛山湖高体鳑鮍的年龄、生长与繁殖     

张堂林  李钟杰  崔奕波 《湖泊科学》2002,(3)

图 3　卵粒大小的频数分布 (ａ)具成熟卵细胞 (ｂ)无成熟卵细胞Ｆｉｇ 3ＦｒｅｑｕｅｎｃｙｄｉｓｔｒｉｂｕｔｉｏｎｏｆｅｇｇｓｉｚｅｏｆＲｈｏｄｅｕｓｏｃｅｌｌａｔｕｓ(ａ)ｗｉｔｈｓｏｍｅｍａｔｕｒｅｅｇｇｓ ,(ｂ)ｗｉｔｈｏｕｔｍａｔｕｒｅｄｅｇｇｓ图 4繁殖力 (Ｆ ,ｅｇｇｓ)与体重 (Ｗ ,ｇ)及全长 (ＴＬ ,ｍｍ )的关系Ｆｉｇ 4Ｒｅｌａｔｉｏｎｓｈｉｐｂｅｔｗｅｅｎｆｅｃｕｎｄｉｔｙ (Ｆ ,ｅｇｇｓ)ａｎｄｂｏｄｙｗｅｉｇｈｔ (Ｗ ,ｇ)ｏｒｔｏｔａｌｌｅｎｇｔｈ (ＴＬ ,ｍｍ)湖北牛山湖高体鳑鮍的年龄、生长与繁殖@…  相似文献   

Basalt platforms in Inner Mongolia and Hebei Province, northeastern China: New K–Ar ages, geochemistries, and revision of palaeomagnetic results     

Zhong Zheng  Hidefumi Tanaka  Yoshiyuki Tatsumi  Masaru Kono 《Geophysical Journal International》2002,151(2):654-662

  相似文献   

南极格罗夫山陨石的研究与展望          下载免费PDF全文

王道德  林杨挺 《极地研究》2003,15(3):161-170

本文综述了我国第 1 5次 ( 1 998/ 1 999)、1 6次 ( 1 999/ 2 0 0 0 )南极科学考察队在东南极格罗夫山冰区回收的 32块陨石的岩石矿物学特征及其分类。这些陨石包括 :2 3块平衡型普通球粒陨石、6块非平衡型普通球粒陨石、1块二辉橄榄岩质火星陨石、1块钙长辉长无球粒陨石、1块未分群的铁陨石。文中还对南极格罗山冰区的陨石富集机制、GRV 980 0 4 (H5 )球粒陨石异常低的宇宙射线暴露年龄、火星陨石的溅射年龄等进行了初步的讨论 ,并对今后格罗夫山陨石的研究提出一些初步想法。  相似文献