·青藏高原地质构造与资源环境研究专栏·(精)

·青藏高原地质构造与资源环境研究专栏·

西藏普兰县马攸木砂金矿床的发现及其意义

多吉1，温春齐2，刘建林1，

巴桑1，官辉1，霍艳2，格桑多庆1

（1.西藏自治区地勘局，西藏拉萨850000；2.成都理工大学，四川成都610059）

摘要：1999年在雅鲁藏布江缝合带西段马攸木地区首先探查到砂金异常，进而通过预查、普查和详查，发现了砂金储量居目前西藏之首的马攸木砂金矿床。该矿床Ⅰ号矿体长为14196.3m，平均宽度为126.61m，平均厚度为11.25m，加权平均品位为0.5116g／m3，砂金资源总量属大型。介绍了Ⅰ号矿体砂金的形态与粒度、成分和成色。马攸木砂金矿床的发现，对西藏地区及古地中海—喜马拉雅成矿域的找矿与成矿理论研究具有重要意义。

关键词：砂金矿床；马攸木；西藏

中图分类号：P618.51文献标识码：A 文章编号：1671－2552（2003）11～12－0896－04 Discovery of the Mayum placer gold deposit BurangCounty Tibet and

its significance

DUOJI1WEN Chunqi2LIU Jianlin1BASANG1GUAN Hui1

HUO Yan2GESANG Duoqing1

(1.Tibet Bureau of Geology and Mineral Eｘploration and Development Lhasa 850000

Tibet China；

2. Chengdu University of Technology Chengdu 610059Tibet China)

Abstract:Placer gold anomalies were found in the Mayum area in the western segment of the Yarlung Zangbo suture zone in 1999 and then through regional appraisal and detailed reconnaissance the Mayum placer gold deposit whose placer gold reserves now rank first in Tibet was found. Orebody No. 1 of this deposit is 14196.3 m long126.61 m wide and 11.25 m thick on the average and has a weighted average grade of 0.5116 g／m3. According to the placer gold resources this deposit belongs to a large one. In the paper the shape grain size composition and fineness of placer gold in orebody No. 1 are introduced. The discovery of the Mayum placer gold deposit has great significance for gold prospecting and the study of the metallogenic theory in Tibet and the Tethys－Himalaya metallogenic domain.

Key words:placer gold deposit Mayum Tibet

藏南特提斯晚侏罗世维美组的沉积环境

江新胜1，2，颜仰基2，潘桂棠2，廖忠礼2，朱弟成2

（1.成都理工大学沉积地质研究所，四川成都610059；

2.中国地质调查局成都地质矿产研究所，四川成都610082）

摘要：对维美组的沉积结构、构造、动物群生态特征、地层展布情况和放射虫硅质岩的产出

环境等进行了分析，认为维美组与其南部的同期沉积门卡墩组顶部石英砂岩一样，同属典型的滨浅海沉积，晚侏罗世康马－隆子和北喜马拉雅地层分区为统一的滨浅海，不存在次深海—深海环境。层序地层分析表明，当时曾发生了陆架海退和陆架暴露事件，造成了大面积石英砂岩的沉积和相关的层序不整合界面。侏罗纪的沉积环境演化与古地理变迁说明，藏南特提斯被动大陆边缘自形成以来并非一成不变，而是经历了多次活动、稳定，海侵、海退的过程。

关键词：藏南特提斯；晚侏罗世；维美组；沉积环境

中图分类号：P534.52文献标识码：A文章编号：1671－2552（2003）11～12－0900－08

Sedimentary environment of the Late Jurassic Ｗeimei Formation

in the southern Tibetan Tethys

JIANG Xinsheng1，2，Y AN Yangji2，PAN Guitang2，LIAO Zhongli2，ZHU Dicheng2（1.Institute of Sedimentary Geology，Chengdu University of Technology，Chengdu

610059，Sichuan，China；

2.Chengdu Institute of Geology and Mineral Resources，China Geological Survey，Chengdu

610082，Sichuan，China）

Abstract：The Weimei Formation is marked by Late Jurassic sediments of the southern Tibetan Tethys and belongs to the Kangmar－Longzi stratigraphic area. Analyses of the sedimentary textures and structures，ecological features of the faunas，stratigraphic distribution and occurrence environment of radiolarian cherts indicate that the Weimei Formation belong to littoral －neritic sediments as is the case with the quartz sandstone at the top of the Menkadun Formation deposited synchronously with it. This suggests that the Late Jurassic Kangmar－Longzi stratigraphic area and the northern Himalayan stratigraphic area constituted a unifying littoral－neritic sea and that no bathyal－abyssal environment existed. Sequence stratigraphic analysis indicates that the event of continental shelf regression and exposure took place at that time，resulting in the extensive deposition quartz sandstone and the formation of unconformity of related stratigraphic sequences. The Jurassic sedimentary environmental evolution and paleogeographic changes suggest that the passive continental margin of the southern Tibetan Tethys did not remain unchanged since its formation but experienced repeated activities，stabilization，transgression and regression.

Key words：southern Tibetan Tethys；Late Jurassic；Weimei Formation；sedimentary environment

藏东南迦巴瓦地区雅鲁藏布江蛇绿混杂岩中

玻安岩的地球化学特征和地质意义

郑来林1，2，耿全如1，欧春生3，王小伟3

（1.中国地质调查局成都地质矿产研究所，四川成都610082；

2.中国地质大学地球科学院，湖北武汉430074；

3.甘肃省地勘局第三地质矿产勘察院，甘肃兰州730050）