赞比亚东北部姆波洛科索盆地沉积地层特征

Sedimentary Stratigraphic Characteristics of The Mporokoso Basin in The North-eastern Zambia

赞比亚东北部姆波洛科索盆地古元古代姆波洛科索群是研究早前寒武纪河流相、浅海相沉积序列和基底组分的重要地层单元。本文通过对该地区岩石地层组成、沉积时代与沉积环境方面进行研究及系统总结,并结合对该地区姆巴拉组实测剖面及其碎屑岩岩石学和地球化学分析数据,获得以下认识:姆波洛科索群可能形成于1860 Ma之后,其上覆卡萨马群可能形成于1434 Ma之后;姆波洛科索盆地沉积环境主要包括:辫状河、冲积扇、湖泊以及浅海等;姆波洛科索群底部姆巴拉组碎屑岩以班委乌卢地块基底花岗岩为主要物源,形成于被动大陆边缘构造背景之下;姆波洛科索盆地可能属于被动大陆边缘型盆地;化探分析数据显示盆地东部与北部地区分别具有金、铀找矿潜力。

The Paleoproterozoic Mporokoso Group in the Mporokoso Basin of north-eastern Zambia is an important stratum for the study of fluvial to shallow-marine sedimentary succession and basal components of the early Precambrian. In this paper, based on the study and systematic summary of lithostratigraphic composition,sedimentary age and environment, combined with the measured section of Mbala Formation and its clastic petrological and geochemical analysis data in the region,the following knowledge is obtained: The Mporokoso Group is supposed to be formed later than 1860 Ma,and the overlying Kasama Group is supposed to be formed later than 1434 Ma;The sedimentary environment of the Mpolokoso Basin mainly includes: braided rivers,alluvial fans,lakes and shallow seas;The clastic rocks of Mbala Formation at the bottom of Mporokoso Group are mainly derived from basement granite of the Bangweulu Block and formed under the passive continental marginal tectonic setting;The Mporokoso Basin may belong to the passive continental marginal basin;Geochemical analysis data have shown potentials for gold and uranium prospecting in the eastern and northern parts of the basin,respectively.