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| 略谈藏东吉塘群 | |
| 引用本文： | 沙绍礼.略谈藏东吉塘群[J].地质与勘探,2012,48(4):768-774. |
| 作者姓名： | 沙绍礼 |
| 作者单位： | 1. 云南省地质调查局,云南昆明,650051 2. 西藏地勘局区域地质调查队,西藏拉萨,851400 3. 云南地勘局第三地质大队,云南大理,671000 4. 云南省地质调查局,云南昆明650051 中国地质大学（北京）,北京100083 5. 金川集团有限公司,甘肃金昌,737100 |
| 基金项目： | 中国地质调查局地质大调查项目(1212010510214) |
| 摘 要： | 摘 要]以往的研究工作将藏东吉塘群分两个组:上部以片岩、变质砂砾岩为主的地层名酉西组;下部以片岩、片麻岩、混合岩为主的地层名恩达组,时代均属前震旦纪。近几年,开展1:25 万编图项目的研究,恩达组可细分为两个岩性段:混合岩段和以片岩、片麻岩、变粒岩、斜长角闪岩及大理岩共同组成的深变质岩段。酉西组中获得新的同位素年龄:240±12Ma( 锆石U-Pb)、226±2Ma( 白云母Ar-Ar),时代可能为古生代,更名为酉西岩群。恩达组的混合岩中新获得锆石SHRIMP U-Pb 同位素年龄254±8Ma、232±9Ma、227±1.8Ma,原1:20 万类乌齐、拉多幅曾于相当恩达组的花岗片麻岩中获得锆石U-Pb年龄253±9Ma、195Ma,这一岩段的混合岩可能是华力西至燕山期变形变质的花岗岩侵入体,应从吉塘群中分离出去。原恩达组中除混合岩外的地层更名为吉塘岩群,时代属古中元古代。 |
| 关 键 词： | 吉塘岩群 古中元古代 酉西岩群 古生代 变质花岗岩 华力西至燕山期 西藏东部 |
| 收稿时间： | 2010/12/31 0:00:00 |
| 修稿时间： | 2/8/2012 12:00:00 AM |
A Brief Discussion of the Jitang Group in Eastern Tibet |
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| SHA Shao-li.A Brief Discussion of the Jitang Group in Eastern Tibet[J].Geology and Prospecting,2012,48(4):768-774. | |
| Authors: | SHA Shao-li |
| Institution: | Yunnan. geological survey,Kunming,Yunnan |
| Abstract: | Abstract:The Jitang rock group is widely distributed in eastern Tibet. Previous researches divided it into two members, i. e. , the upper Youxi Formation, composed of albite-quartz-schist, albite-twomica-schist and albite-actinolite-schist, and the lower Enda Formation, mainly composed of biotite -twomica-gneiss, granitic gneiss and quartz-schist, both of which belong to the pre-Sinian period. In recent years, geological mapping at a scale of 1: 250000 divided the Enda Formation into two members, i. e. the migmatite member and hypometamorphic member composed of schist, gneiss, granulite, amphibolite and marble. Geological mapping obtained the isotopic age as 240±12Ma (Zircon U-Pb) and 226.1±2.4(Ar-Ar)for the Youxi Formation, belonging to Paleozoic. Thus, the Youxi Formation is renamed as Youxi rock group. Migmatite from the Enda Formation obtained zircon SHRIMP U-Pb isotopic ages as 254±8Ma, 232±9Ma and 227±1.8Ma. The previous 1:200000 regional survey has measured the zircon U-Pb age as 253±9Ma and 195Ma. This may suggest that this rock member may be the Variscan to Yanshanian metamorphosed granitic intrusions, and should be removed from the Jitang group. The original Enda Formation is the real pre-Sinian Jitang group, composed of gneiss, mica schist, quartz schist, gneiss-based folder granulite, amphibolite rocks and marble, and is attributed to the Mesoproterozoic period. |
| Keywords: | Jitang Group Mesoproterozoic Youxi Group paleozoic metamorphic granite from Variscan to Indosinian eastern tibet |
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