下雷-东平锰矿带矿床特征和成因探讨

Characteristics and Genesis of Deposits in the Xialei-Dongping Manganese Ore Belt of Guangxi Province

下雷-东平锰矿带是我国重要的锰矿矿集区。在矿集区典型锰矿床的野外工作基础上,对含锰岩系和矿石开展了岩石学、岩石化学、微量元素地球化学分析研究,比较了同一锰矿带的下雷式、东平式两类锰矿床特征。结合前人区域构造资料,探讨了下雷式、东平式两类锰矿成因。研究认为下雷式锰矿形成于被动大陆边缘,热水作用参与了锰矿的形成;而东平式锰矿形成于被动大陆边缘向前陆盆地过渡带,成矿过程中火山活动强烈,推测东平锰矿的沉淀富集作用与海底火山喷发具有一定的相关性。

The Xialei- Dongping manganese ore belt is an important ore concentration area in China. Based on field work on the typical Mndeposits,we have conducted research on petrological characteristics,major element content,and trace element content of ore- bearing formation. We compared the characteristics of Xialei- type manganese deposits and Dongping- type manganese deposits which formed in the same ore- forming belt. Combined with regional tectonic data from previous studies,we explored the genesis of the two types of deposits. Our research suggest that the Xialei- type Mn- deposits formed in a passive continental margin,where hydrothermal activity played an important role in the formation of Mn- deposits,while the Dongping- type Mn- deposits were generated in a transition from a passive continental margin to a foreland basin where volcanic activity was intensive. We infer that the formation of the Dongping- type Mn- deposits was related to volcanic eruptions at the seafloor.