Airborne geophysics and geochemistry provide new insights in the intracontinental evolution of the Mesoproterozoic Kibaran belt (Central Africa)
Airborne geophysics and geochemistry provide new insights in the intracontinental evolution of the Mesoproterozoic Kibaran belt (Central Africa)
复制标题
航空地球物理学和地球化学为中元古代基巴兰带（中非）的陆内演化提供了新的见解
作者：
M. Fernandez;K. Theunissen
The Mesoproterozoic Kibaran belt in southwest Rwanda (Central Africa) consists of two contrasting metamorphic sequences. The first is essentially composed of weakly deformed, low-grade pelitic rocks with many quartzitic intercalations and some volcano-sedimentary sequences. The second consists of medium- to high-grade metamorphic metasediments and gneisses, intruded by sheared granitoids. Existing geological maps are of limited use in understanding the evolution of this part of the Kibaran belt. A combination of airborne γ-spectrometry data with Landsat TM imagery readily distinguishes known lithologies, and in particular detects two distinct granite types. Trace element data for one granite type does not correspond with known petrochemical trends of Kibaran granites, and may belong to a pre-Kibaran basement. The combining of these data with a recently published schematic geological map of the northeast Kibaran belt and re-interpreted field structural data, suggests a model for the Kibaran orogenic evolution in terms of extensional detachment tectonics and associated metamorphic core complexes.
