Heritier Rub'son N'nahano, Li Huan, Ibrahim Mohammed Abdalla Elsharif, Nambaje Claude, Luemba Moise
Key Laboratory of Metallogenic Prediction of Nonferrous Metals and Geological Environment Monitoring, Ministry of Education, School of Geosciences and Info-Physics, Central South University, Changsha, 410083, China.
Centre for Earth Sciences, Indian Institute of Science, Bangalore, 560012, India.
Heliyon. 2024 Jun 18;10(12):e33222. doi: 10.1016/j.heliyon.2024.e33222. eCollection 2024 Jun 30.
The Twangiza-Namoya Gold Deposit within the Kibaran Belt of the Democratic Republic of the Congo represents a crucial manifestation of the hydrothermal gold system. This review investigates its intricate origin and the subsequent metallogenic evolution that has shaped its present-day characteristics and offers a systematic categorization based on its deposition processes and geotectonic settings. The findings reveal that the gold deposits are predominantly derived from sedimentary fluid sources. Within this vast metallogenic province, two stages of gold deposition have been constrained: (a) the early-stage formation related to the accretion of Rodinia assembly with subduction-collisional event where diagenesis cemented the syngenetic pyrite carbonaceous sediments and (b) the later stage deposition related to the continent-collisional event during the last stage of Rodinia supercontinent amalgamation. Previous isotopic investigations, with a particular emphasis on pyrite sulfur isotopes on both host rocks and vein-bearing sulfides, have been instrumental in tracing the origins of gold-bearing fluids in the study region. The isotopic variance in the four deposits: Twangiza (-5.2 % to +3 %, avg. -0.3 %), Kamituga (-0.6 % to -0.9.1 %, avg. -5%), Lugushwa (+3.0 % to -18.4 %), and Namoya, on the southernmost end, has a vast range but with much heavier isotope compositions, ranging between +1.3 % and to +22.6 %, with an average of +12.2 %. The data predominantly points to the sedimentary origins of ore fluids in the Twangiza-Namoya Gold belt, highlighting the pivotal role of sedimentary processes in shaping the metallogenic landscape of the region. The fluids inclusions depicted the deposits to be formed from HO-Nacl-HO with abundant CH and N ore-forming fluid, moderate temperature (350-500 °C), and low salinity. The overall results confirm the genetic style of the Twangiza-Namoya Gold Belt to be an orogenic gold-style deposit that was emplaced during the early Neoproterozoic era in low greenschist facies terrain.
刚果民主共和国基巴拉带内的特旺吉扎-纳莫亚金矿是热液金系统的一个关键表现。本综述研究了其复杂的成因以及塑造其现今特征的后续成矿演化，并根据其沉积过程和大地构造背景进行了系统分类。研究结果表明，金矿床主要源自沉积流体源。在这个广阔的成矿省内，已确定了两个金沉积阶段：(a) 早期形成与罗迪尼亚大陆组合增生及俯冲碰撞事件有关，成岩作用胶结了同生黄铁矿碳质沉积物；(b) 后期沉积与罗迪尼亚超大陆合并最后阶段的大陆碰撞事件有关。先前的同位素研究，特别是对主岩和含矿脉硫化物的黄铁矿硫同位素的研究，有助于追踪研究区域内含金流体的来源。四个矿床的同位素变化：特旺吉扎（-5.2%至+3%，平均-0.3%）、卡米图加（-0.6%至-0.91%，平均-5%）、卢古什瓦（+3.0%至-18.4%）以及最南端的纳莫亚，变化范围很大，但同位素组成要重得多，介于+1.3%至+22.6%之间，平均为+12.2%。数据主要表明特旺吉扎-纳莫亚金带中矿液的沉积起源，突出了沉积过程在塑造该区域成矿景观中的关键作用。流体包裹体显示这些矿床由富含CH和N的HO-Nacl-HO成矿流体形成，温度适中（350-500°C），盐度较低。总体结果证实特旺吉扎-纳莫亚金带的成因类型为造山型金矿床，形成于新元古代早期低绿片岩相地形中。
