| 甘肃碌曲拉尔玛金矿地质特征及成因探讨 |
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| 引用本文：.1994.A preliminary discussion on geological characteristics and genesis of the Laerma gold deposit in Luqu county，Gansu province.[J].Mineral Deposits,13(1):19~27 |
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| 基金项目:“七五”国家科技攻关项目中《秦岭西段微细浸染型金矿成矿条件及成矿预测》75-55-金-18课题的部分研究成果。 |
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| 中文摘要:拉尔玛金矿位于秦岭褶皱带的白龙江复背斜轴部西端倾伏部位，主要赋存在下
寒武统含碳绢云母板岩及含碳硅质板岩中。矿体呈层状、似层状、分枝状产出。金呈超（次）显微金存在于石英、辉梯矿、重晶石中。本区以中低温矿物组合为特征，尤以汞-梯-砷组合与金的关系密切。根据矿床的硫、氧、氢同位素组成、矿物包裹体测温以及物理化学参数的计算，认为本区成矿物质主要来自控矿地层本身，具浅成中性强还原中低温低压成矿环境，其成因类型属热液改造型金矿床。 |
| 中文关键词:拉尔玛金矿 地质特征矿床成因 甘肃碌曲 |
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| A preliminary discussion on geological characteristics and genesis of the Laerma gold deposit in Luqu county，Gansu province. |
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| Abstract:The Laerma gold deposit，discovered in 1985，OCCllFS in Lower Cambrian carbonaceous sericite slate and carbonaceous siliceous slate and belongs to fine-dissemination type．The gold orebodies，generally irregular and assuming strafiform or irregular form，are strictly confined to the principal fault Fa，with the ore—bearing rocks being black rocks of the epimetamorphic formation．Gold occurs as ultramicroscopic particles in quartz，pyrite，barite and stibnite as well
as sinail amounts of realgar．pyrrhotite and 1imonite．AIterations are silicification，pyritization，sericitization and carbonatization，with silicification being dominant．The ore-forming process might be divided into two epochs：hydrotherreal epoch(which cart be subdivided into four stages)and supergene epoch.
The ore-forming process proceeded under the following conditions：temperature 200～261℃; low pressure, small depth; oxygen fugacity-33～-52；Eh-0.4～-0.68V; weakly acid ore-forming media; δ34S-25.20‰～+15.5‰(sulfides); δ18O+13.18‰～+16.55‰(quartz and calcite), δD-90.87‰～102.59‰ (fluid inclusions). In addition, gold content of Lower Cambrian is higher than the background value of gold. All these physical-chemical parameters indicate that ore-forming materials oame mainly from wall rocks.
According to geological characteristics of the ore deposit，the Laerma gold deposit is believed to be genetically of hydrothermal reformation type. |
| keywords:the Laerma gold deposit, geological characteristics, genesis of the ore deposit, Luqu County of Gansu province |
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