| 西藏谷露热泉型铯矿床年代学及意义 |
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| 引用本文： | 赵元艺,赵希涛,马志邦,邓坚.西藏谷露热泉型铯矿床年代学及意义[J].地质学报,2010,84(2):211-220. |
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| 作者姓名： | 赵元艺 赵希涛 马志邦 邓坚 |
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| 作者单位： | 1. 中国地质科学院矿产资源研究所,北京,100037
2. 中国科学院地质与地球物理研究所,北京,100029 |
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| 基金项目： | 国家自然科学基金项目(编号40672066、40302028);;国土资源部百人计划项目;;中国地质科学院矿产资源研究所中央级公益性科研院所基本科研业务费项目(编号K0809);;科技部“973”项目(编号2002CB412606)资助成果 |
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| 摘 要： | 谷露间歇喷泉位于西藏那曲地区那曲县谷露乡西北的桑曲西岸,海拔4700～4750m,现今仍在强烈活动中,其以硅华为主的泉华沉积形成了热泉型中型硅华铯矿床,属印度-亚洲陆陆碰撞效应的产物。本文根据野外第四纪地质与地貌的系统调查研究,将硅华分为南、北两区共5套沉积。由泉胶砾岩组成的第Ⅰ套硅华下伏于南区大硅华台地之下,并越过桑曲而延伸至河东,构成倒数第二次冰期(爬然冰期)冰水沉积的基座。第Ⅱ套硅华组成南区的大硅华台地。由泉胶砾岩组成的第Ⅲ套硅华下伏于北区硅华台地之下,也越过桑曲延伸至河东,构成末次冰期(拉曲冰期)冰水沉积的基座。第Ⅳ套硅华构成北区硅华台地,已被一东西向小沟分为南、北两个小片,均由数列小的硅华锥组成。第Ⅴ套硅华则为现今仍在活动和堆积的硅华锥。根据9个样品的U系法测年结果,并参考野外地貌与第四纪地质的研究结果,可将这5套硅华的铯矿床的形成,划分为如下5个阶段:第1阶段虽暂缺年龄数据,但可按地貌部位和地层层序,判断其堆积于倒数第三次冰期(宁中冰期)以后,很可能为0.5～0.4MaBP之间的大间冰期早中期;第2阶段为0.38～0.25MaBP,相当于大间冰期晚期至爬然冰期早期;第3阶段为0.22MaBP前后的爬然冰期早期;第4阶段为108.6～17.2kaBP的晚更新世的末次间冰期晚期至拉曲冰期;第5阶段为5.3kaBP的全新世中期以来。由老到新,各期泉华的SiO2含量呈现出明显的降低趋势,而铯含量则呈升高趋势,是随着矿石中SiO2有序度的降低而其他成分被保留在晶格中所致。
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| 关 键 词： | 热泉型铯矿床 U系法测年 硅华 谷露 西藏 |
| 收稿时间： | 2008/12/9 0:00:00 |
| 修稿时间： | 7/24/2009 4:48:28 PM |
A Study on Chronology and Geological Significance for Hot Spring Cesium Deposit of Gulu, Nagqu, Tibet |
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| ZHAO Yuanyi,ZHAO Xitao,MA Zhibang and DENG Jian.A Study on Chronology and Geological Significance for Hot Spring Cesium Deposit of Gulu, Nagqu, Tibet[J].Acta Geologica Sinica,2010,84(2):211-220. |
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| Authors: | ZHAO Yuanyi ZHAO Xitao MA Zhibang and DENG Jian |
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| Abstract: | Gulu hot spring is located on the west bank of Sangqu river,Gulu town, Nagqu county of Tibet .The elevation is about 4700～4750m a.s.l. . It is still intensely activing. Consisted mainly by geyserite,the sinter formed a medium scale hot spring type Cs-deposit. It is the result of collision of Indian and Eurasian plates. On the basis of investigating the characteristics of the geology and geomorphology, this paper divided the sinter into,south and north areas,5 suites. Suite 1 is located in the south area and under the big geyserite platform. It cut across the Sangqu river and reaches its east bank and formes the fluvioglacial platform of the Penultimate Glacial Period (Paran Glacial Period ). Suite 2 consists of the big geyserite platform of the south area.Consists of conglomerate cemented by sinter, Suite 3 located under geyserite platform of the north area and cut across the Sangqu river and reaches the east bank too. Which Consists of the fluvioglacial platform of the Last Glaciation (Laqu Glacil Period)of the late Late Pleistocene. Suite 4 Consists of the geyserite platform of the north area and is divided into,south and north,two small parts separated by a small ditch. Everyone of the two parts consisted by several geyserite pyramids. Suite 5 consists of the geyserite pyramids that modern activing. According to nine U-series dates from Gulu geyserite and the characteristics of the geology and geomorphology, this paper divided Gulu Cs-deposit into five stages. Stage 1,although We have not get the dates temporarily, according to the position of geomorphology and stratigrphic sequence,which can be inferred that it is deposit after Ningzhong glacial period, maybe the early-middle stage of the largest International period (about 0.5～0.4 Ma) .Stage 2 is 0.38～0.25Ma BP. It is correspond from the late stage of the largest International period to the early stage of Paran glacial period. Stage 3 is about 0.22 Ma BP which is the early stage of Paran glacial period. Stage 4 is 108.6～17.2 ka BP that is formed from late stage of the Last Glaciation to the Laqu glacial period. Stage 5 is from 5.3 ka BP, to the present. From early to late stage, the content of SiO_2 gradually falls,while contents of Cs rise. The reason is that impurity components are not expelled from crystals with the falling degree of SiO_2 ordering. |
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| Keywords: | hot spring type Cs-deposits U-series dating geyserite Gulu Tibet |
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