| 河淮地幔亚热柱的演化及其对华北地区成矿的控制作用 |
| |
| 关键词:mantle plume mantle branch structure mineralization north China platform |
| 基金项目:“八·五”地矿部地质找矿科技攻关项目,地矿部重点基础地质研究项目 |
|
| 摘要点击次数: 3432 |
| 全文下载次数: 2448 |
| 摘要: |
| The Formation of Hehuai Sub-mantle Plume and Its Controlling to the Mineralization in North China |
| Based on the geophysical prospecting, volcanic-magmatic activities, sedimentary formation and structural evolution in eastern part of North China platform, it is proposed that Hehuai area has been an intensively uplifted submantle plume since the Mesozoic. Duo to the intensive uplifting of the submantle plume, the lower lithosphere was thinned and the .upper crust was down faulted. Cenozoic sediments are up to 5-9km thick. The lithosphere was only 60-80km thick.The uplifting submantle plume was blocked at the bottom of lithosphere. The mantle plume.changed into half-spherical (shaped like a umbrella) and extended towards the surroundings. This made the middle-lower crust form gently declined detachmenting flow deformation layer (low velocity layer). As the mantle-crust interface gradually increased to 100-160km towards the surrounding, inadequate gravity resulted in uplifting of the crust and formed orogenic zone along the margin of the submantle plume. Meanwhile, the sharply declined ductile shearing zone in the axis of the orogenic zone cut off gently declined crust-mantle detachmenting flow deformation zone,the depressure and unloading made the soften rocks form anatectic magyna. Anatectic magyna melted some country rocks and intruded along the ductile shearing zone, this speeded up the uplifting of orogenic zone and formed the third class tectonic unit of the montle plume-mantle branch structure. The cover was openly detachmented in the place of quickly uplifting area. meta-morphosed basement rocks were exposed to form typical metamorphic core complex.Mineralization elements (such as An and Ag) which mainly came from the core moved up as gas with the mantle plume. In the submantle environment, some gaseous mineralization elements changed into liquid and moved up as gas-liquid mixture. When the umbrella-like extended submantle plume was cut off by sharply declined ductile shearing zone in orogenic belt, gas-liquid Au and Ag immigrated up with the anatectic magma along the ductile shearing zone and concentrated in favorable place to form industry deposits in mantle branch structure (metamorphic core complex). |
| NIU Shu-yin,SUN Ai-qun,LI Hong-yang,ZHANG Jian-zhen,LUO Dian-wen,YE Dong-hu,WANG Jin-suo.1996.The Formation of Hehuai Sub-mantle Plume and Its Controlling to the Mineralization in North China[J].Acta Geoscientica Sinica,17(4):413-423. |
| 查看全文 查看/发表评论 下载PDF阅读器 |
|
|
|
|
|