摘要
欢乐谷地区由新元古代泥砂质岩层夹铁镁质岩层组成。受达马拉期陆块碰撞事件的影响，发生区域中深地壳层次的强烈韧性变形。后碰撞期，在地壳增厚背景下，发生大规模伸展减薄和花岗岩浆作用，形成多种浅色花岗岩体即白岗岩。产铀白岗岩主要为D型及E型白岗岩，为S型壳源花岗岩。欢乐谷地区经历了四期五个阶段的构造演化，分别是：前达马拉期构造变形、达马拉碰撞造山期韧性变形（早阶段的挤压逆冲、晚阶段的走滑剪切韧性变形）、后达马拉期脆性变形和新生代整体抬升引起的脆性变形。广泛发育的白岗岩属于同构造期岩体。通过对变质岩和白岗岩的节理测量统计，基本确定了研究区的碰撞后区域应力场。最优势的主压应力方向介于N26°～35°方位间，其次为介于N110°～129°方位间和N345°-360°方位间的主压应力。目前保留在各类岩石中的密集节理构造，是碰撞造山后构造折返或岩浆上涌到达上地壳层次后才发生的，与铀矿富集关系密切。本研究初步探讨了达马拉期构造作用、韧性剪切、后期脆性断裂（基性岩墙侵位通道）与铀成矿作用的成因联系和制约作用。
The Gaudeanmus area is composed of Neoproterozoic felsic rocks interbedded with mafic rocks. This area experienced deep crustal strong ductile deformation, under the tectonic setting of continental collision events of the Damara phase. In the post-collision stage, extensive stretch thinning and granite magmatism formed a variety of leucogranites （alskites）. Uranium minerals mainly exists in type D and type E of alaskites which are S- granites source from crust. The Gaudeanmus area has experienced four period and five stages of tectonic evolution ： pre-Damara stage structure deformation, Damara collisional orogenic stage ductile deformation （early stage of thrust extrusion and late stage of the strike-slip ductile shear deformation ） , post-Damara stage brittle deformation and Cenozoic uplifting related brittle deformation, respectively. The extensively developed granites belong to syntectonic plutons. Measurement of joints in the metamorphic rocks and granites yielded, thousands groups occurrences of joints from 27 locations, basically determining the regional after collision stress field in the study area. The most principal compressive stress direction is between N260° ~ 35°~, followed by those between N110° -129° and N345° -360°. The dense joint structures preserved in all kinds of rocks were formed by post-tectonic tectonic exhumation or magma upwelling that reached upper crust levels, which are closely associated with uranium enrichment. This study further discussed the Damara phase structure, ductile shear, the late stage brittle structure associated with the genesis of uranium mineralization.
出处
《地质论评》
CAS
CSCD
北大核心
2016年第1期83-93,共11页
Geological Review
基金
核能开发科研项目(编号:HF230)“非洲中南部古老地块铀矿综合识别评价技术及应用研究”的成果~~
关键词
构造变形
白岗岩
铀成矿作用
欢乐谷
纳米比亚
Tectonic episodes
Alaskite
Uranium metallization
Gaudeanmus
Namibia.
