云南曲靖地区下寒武统黑色岩系岩石地球化学特征与成因

Geochemistry and Genesis of Lower Cambrian Black Rocks from Qujing Area, Yunnan Province, China

在曲靖地区下寒武统富钼镍黑色岩系出露较好的马龙县纳章镇石龙村和沾益县德泽乡热水村,进行了筇竹寺组地质剖面实测,同时对所采集的黑色岩系岩石和富钼镍矿石,进行了主量、微量和稀土元素含量分析。区域古地理特征表明曲靖地区黑色岩系形成于滨岸-浅海环境,实测剖面和岩石组构特征反映黑色岩系形成于缺氧还原、低能热水沉积环境,岩石地球化学特征暗示曲靖地区富钼镍黑色岩系的沉积过程有生物作用参与,并伴有热水喷流作用,其成岩物质主要来源为陆源碎屑,少量为深部物质。

In the geological cross sections between Shilong and Reshui villages in Malong and Zhanyi Counties, respectively, in Qujing area, Yunnan Province, China, Lower Cambrian black rock series were exposed widely. Black series rocks and Mo-Ni ores were analyzed for the contents of the major, trace and rare earth elements. The regional paleogeographic characteristics indicate that the black rock series in Qujing area formed in the environment of beach shore or shallow sea. The field section and rock fabrics reflect that the black series formed in anoxic hot water deposition environment with lower energy. The geochemical features of black series imply that some creatures were participated in the deposition process of the black series in Qujing area and were associated with the hydrothermal exhalative process. The black rock-forming materials were mainly terrigenous fragments with a little deep material.